325 research outputs found
New Perspectives on the Laminar Boundary Layer Physics in a Polarized Pressure Field with Temperature Gradient: an Analytical Approximation to Blasius Equation
This study proposes a semi-analytic approximation to the laminar boundary layer growth in a polarized pressure field with temperature gradient represented by the joint Blasius-energy equation. We illuminate that is a probability density function (PDF) approximated by an amended Gaussian PDF with zero mean and standard deviation . This implies a diffusive structure for the molecular momentum conversion as well as the energy flux in the boundary layer. A new limit for the boundary layer edge is also presented. Results suggest an augmented boundary layer when compared to accepted values in the literature. We also reproduce the inverse proportionality of the free stream velocity to the diffusion of both momentum and energy
The effect of instrumental stray light on Brewer and Dobson total ozone measurements
Dobson and Brewer spectrophotometers are the primary, standard
instruments for ground-based ozone measurements under the World
Meteorological Organization's (WMO) Global Atmosphere Watch program. The
accuracy of the data retrieval for both instruments depends on a knowledge of
the ozone absorption coefficients and some assumptions underlying the data
analysis. Instrumental stray light causes nonlinearity in the response of
both the Brewer and Dobson to ozone at large ozone slant paths. In addition,
it affects the effective ozone absorption coefficients and extraterrestrial
constants that are both instrument-dependent. This effect has not been taken
into account in the calculation of ozone absorption coefficients that are
currently recommended by WMO for the Dobson network. The ozone absorption
coefficients are calculated for each Brewer instrument individually, but in
the current procedure the effect of stray light is not considered. This
study documents the error caused by the effect of stray light in the Brewer
and Dobson total ozone measurements using a physical model for each
instrument. For the first time, new ozone absorption coefficients are
calculated for the Brewer and Dobson instruments, taking into account the
stray light effect. The analyses show that the differences detected between
the total ozone amounts deduced from Dobson AD and CD pair wavelengths are
related to the level of stray light within the instrument. The discrepancy
introduced by the assumption of a fixed height for the ozone layer for ozone
measurements at high latitude sites is also evaluated. The ozone data
collected by two Dobson instruments during the period of December 2008 to
December 2014 are compared with ozone data from a collocated double
monochromator Brewer spectrophotometer (Mark III). The results illustrate the
dependence of Dobson AD and CD pair measurements on stray light.</p
New Dihydroxytyrosyl Esters from Dicarboxylic Acids: Synthesis and Evaluation of the Antioxidant Activity In Vitro (ABTS) and in Cell-Cultures (DCF Assay)
New dihydroxytyrosyl esters 2a, 2c-2j of dicarboxylic acids were synthesized from methyl orthoformate protected hydroxytyrosol 3 and diacyl chlorides. New compounds were characterized (HRMS, FT-IR, 1H- and 13C-NMR), and tested for antioxidant activity both in vitro (ABTS) and on L6 myoblasts and THP1 leukemic monocytes cell culture by DCF assay. According to the ABTS assay, compounds 2a, 2c-2j showed a TEAC value of antioxidant capacity up to twice that of Trolox. Very high or complete ROS protections were obtained in the cell environment where lipophilicity and rigidity of dicarboxylic structure seem to facilitate the antioxidant effect. MTT assay and proliferation test were used for assessment of cell viability. These compounds can be envisaged as a new class of preservatives for food or cosmetic products
Measurements of scattering observables for the break-up reaction
High-precision measurements of the scattering observables such as cross
sections and analyzing powers for the proton-deuteron elastic and break-up
reactions have been performed at KVI in the last two decades and elsewhere to
investigate various aspects of the three-nucleon force (3NF) effects
simultaneously. In 2006 an experiment was performed to study these effects in
break-up reaction at 135 MeV with the detection system, Big
Instrument for Nuclear polarization Analysis, BINA. BINA covers almost the
entire kinematical phase space of the break-up reaction. The results are
interpreted with the help of state-of-the-art Faddeev calculations and are
partly presented in this contribution.Comment: Proceedings of 19th International IUPAP Conference on Few-Body
Problems in Physics, Bonn University, 31.08 - 05.09.2009, Bonn, GERMAN
Supporting small and medium-sized enterprises in the educational technology sector to become more research-minded: Introduction to a small collection
The EDUCAtional Technology Exchange programme (EDUCATE) at UCL Institute of Education provides the context for this paper, which describes the programme’s vision, objectives and key activities, and sets the context for the collection of articles that follow. This university-led programme was underpinned by Luckin’s (2016) golden triangle of evidence-informed educational technology (edtech) as it sought to support 252 small and medium-sized enterprises to become more research-informed through a six-month research training and mentoring programme. The evaluation of the programme’s design-based research cycles revealed the importance of the careful choice and evolution of its boundary objects. These boundary objects, namely each enterprise’s ‘logic model’ and research proposal, facilitated meaningful conversations between the programme’s research mentors and the enterprises. These boundary objects involved several iterations, during which the language of the two communities became more aligned, helping to bridge the academic knowledge and practices with those of the enterprises
Molecular portrait of high alpha-fetoprotein in hepatocellular carcinoma: implications for biomarker-driven clinical trials
The clinical utility of serum alpha-fetoprotein (AFP) in patients with hepatocellular carcinoma (HCC) is widely recognised. However, a clear understanding of the mechanisms of AFP overexpression and the molecular traits of patients with AFP-high tumours are not known. We assessed transcriptome data, whole-exome sequencing data and DNA methylome profiling of 520 HCC patients from two independent cohorts to identify distinct molecular traits of patients with AFP-high tumours (serum concentration?>?400?ng/ml), which represents an accepted prognostic cut-off and a predictor of response to ramucirumab. Those AFP-high tumours (18% of resected cases) were characterised by significantly lower AFP promoter methylation (p?<?0.001), significant enrichment of progenitor-cell features (CK19, EPCAM), higher incidence of BAP1 oncogene mutations (8.5% vs 1.6%) and lower mutational rates of CTNNB1 (14% vs 30%). Specifically, AFP-high tumours displayed significant activation of VEGF signalling (p?<?0.001), which might provide the rationale for the reported benefit of ramucirumab in this subgroup of patients
An Immune Gene Expression Signature Associated With Development of Human Hepatocellular Carcinoma Identifies Mice That Respond to Chemopreventive Agents
Program (HEPCAR, reference no. 667273-2); US Department of Defense(CA150272P3); an Accelerator Award (CRUCK, AECC, AIRC) (HUNTER,reference no. C9380/A26813), NCI Cancer Center Support Grant, National Cancer Institute; Tisch Cancer Institute (P30-CA196521); Samuel Waxman Cancer Research Foundation; Spanish National Health Institute (SAF2016-76390); and the Generalitat de Catalunya/AGAUR (SGR-1358). Agrin Moeini is supported by Spanish National Health Institute. Sara Torrecilla and Judit Peix are funded by Centro de Investigación Biomedica en Red de Enfermedades Hepáticas y Digestivas (Ciberehd-ISCIII). Carla Montironi is a recipient of Josep Font grant. Carmen Andreu-Oller is supported by "la Caixa" INPhINIT Fellowship Grant (LCF/BQ/IN17/11620024). Roser Pinyol is supported by HEPCAR and AECC. Daniela Sia is supported by the Gilead Sciences Research Scholar Program in Liver Disease. Scott L. Friedman is supported by the National Institutes of Health Research project grant (R01,DK5662) and US Department of Defense (CA150272P3). Mathias Heikenwälder was supported by an ERC Consolidator grant (HepatoMetaboPath), the SFBTR 209, 1335 and SFBTR179.Background & Aims: Cirrhosis and chronic inflammation precede development of hepatocellular carcinoma (HCC) in approximately 80% of cases. We investigated immune-related gene expression patterns in liver tissues surrounding early-stage HCCs and chemopreventive agents that might alter these patterns to prevent liver tumorigenesis. Methods: We analyzed gene expression profiles of nontumor liver tissues from 392 patients with early-stage HCC (training set, N = 167 and validation set, N = 225) and liver tissue from patients with cirrhosis without HCC (N = 216, controls) to identify changes in expression of genes that regulate the immune response that could contribute to hepatocarcinogenesis. We defined 172 genes as markers for this deregulated immune response, which we called the immune-mediated cancer field (ICF). We analyzed the expression data of liver tissues from 216 patients with cirrhosis without HCC and investigated the association between this gene expression signature and development of HCC and outcomes of patients (median follow-up, 10 years). Human liver tissues were also analyzed by histology. C57BL/6J mice were given a single injection of diethylnitrosamine (DEN) followed by weekly doses of carbon tetrachloride to induce liver fibrosis and tumorigenesis. Mice were then orally given the multiple tyrosine inhibitor nintedanib or vehicle (controls); liver tissues were collected and histology, transcriptome, and protein analyses were performed. We also analyzed transcriptomes of liver tissues collected from mice on a choline-deficient high-fat diet, which developed chronic liver inflammation and tumors, orally given aspirin and clopidogrel or the anti-inflammatory agent sulindac vs mice on a chow (control) diet. Results: We found the ICF gene expression pattern in 50% of liver tissues from patients with cirrhosis without HCC and in 60% of nontumor liver tissues from patients with early-stage HCC. The liver tissues with the ICF gene expression pattern had 3 different features: increased numbers of effector T cells; increased expression of genes that suppress the immune response and activation of transforming growth factor β signaling; or expression of genes that promote inflammation and activation of interferon gamma signaling. Patients with cirrhosis and liver tissues with the immunosuppressive profile (10% of cases) had a higher risk of HCC (hazard ratio, 2.41; 95% confidence interval, 1.21-4.80). Mice with chemically induced fibrosis or diet-induced steatohepatitis given nintedanib or aspirin and clopidogrel down-regulated the ICF gene expression pattern in liver and developed fewer and smaller tumors than mice given vehicle. Conclusions: We identified an immune-related gene expression pattern in liver tissues of patients with early-stage HCC, called the ICF, that is associated with risk of HCC development in patients with cirrhosis. Administration of nintedanib or aspirin and clopidogrel to mice with chronic liver inflammation caused loss of this gene expression pattern and development of fewer and smaller liver tumors. Agents that alter immune regulatory gene expression patterns associated with carcinogenesis might be tested as chemopreventive agents in patients with cirrhosis
Definition of a new (Doniach-Sunjic-Shirley) peak shape for fitting asymmetric signals applied to reduced graphene oxide/graphene oxide XPS spectra
The existence of asymmetry in X-ray photoelectron spectroscopy (XPS) photoemission lines is widely accepted, but line shapes designed to accommodate asymmetry are generally lacking in theoretical justification. In this work, we present a new line shape for describing asymmetry in XPS signals that is based on two facts. First, the most widely known line shape for fitting asymmetric XPS signals that has a theoretical basis, referred to as the Doniach-Sunjic (DS) line shape, suffers from a mathematical inconvenience, which is that for asymmetric shapes the area beneath the curve (above the x-axis) is infinite. Second, it is common practice in XPS to remove the inelastically scattered background response of a peak in question with the Shirley algorithm. The new line shape described herein attempts to retain the theoretical virtues of the DS line shape, while allowing the use of a Shirley background, with the consequence that the resulting line shape has a finite area. To illustrate the use of this Doniach-Sunjic-Shirley (DSS) line shape, a set of spectra obtained from varying amounts of graphene oxide (GO) and reduced GO on a patterned, heterogeneous surface are fit and discussed
Elastic proton-deuteron scattering at intermediate energies
Observables in elastic proton-deuteron scattering are sensitive probes of the
nucleon-nucleon interaction and three-nucleon force effects. The present
experimental data base for this reaction is large, but contains a large
discrepancy between data sets for the differential cross section taken at 135
MeV/nucleon by two experimental research groups. This paper reviews the
background of this problem and presents new data taken at KVI. Differential
cross sections and analyzing powers for the and
reactions at 135 MeV/nucleon and 65 MeV/nucleon,
respectively, have been measured. The data differ significantly from previous
measurements and consistently follow the energy dependence as expected from an
interpolation of published data taken over a large range at intermediate
energies.Comment: 5 pages, 4 figures, submitted to PR
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