2,129 research outputs found
Assessing the uncertainty on particle size and shape: implications for ESR and OSL dating of quartz and feldspar grains
Grain size and shape are two important parameters in Electron Spin Resonance (ESR) and Optically Stimulated Luminescence (OSL) dating of sediment, since they have a direct impact on several correction factors that are used for evaluating the dose rate. These parameters were evaluated by static image analysis for a wide range of quartz and feldspar grain samples. Our results indicate that there are many factors that may influence the final grain size and shape. Overall, grains are not perfect spheres, but should be rather approximated to smooth slightly elongated ellipsoids, with a width that is on average about 25% smaller than the length. For multiple grains dating, this may have an influence of a few percents on the beta dose rate evaluation, and thus even less on the total dose rate. However, in the case of single grain dating, the impact may be somewhat more significant given the large variability in size and shape between grains that may be encountered in a natural sediment. For beta micro-dosimetry purpose, it may be thus useful to better characterize the single grain that is going to be dated.This study was partially sponsored by a project from the Spanish Ministry of Science and Innovation (Grant number: CGL2010-16821). MD is currently the recipient of an International Outgoing Fellowship from the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement PIOF-GA-2013-626474. IC is the beneficiary of a PhD scholarship from the Spanish MINECO
(project CGL2012-38434-C03-02)
Ethnicity associated microbial and metabonomic profiling in newly diagnosed ulcerative colitis
Introduction: Ulcerative colitis (UC) differs across geography and ethnic groups. Gut microbial diversity plays a pivotal role in disease pathogenesis and differs across ethnic groups. The functional diversity in microbial-driven metabolites may have a pathophysiologic role and offer new therapeutic avenues. Methods: Demographics and clinical data were recorded from newly diagnosed UC patients. Blood, urine and faecal samples were collected at three time points over one year. Bacterial content was analysed by 16S rRNA sequencing. Bile acid profiles and polar molecules in three biofluids were measured using liquid-chromatography mass spectrometry (HILIC) and nuclear magnetic resonance spectroscopy. Results: We studied 42 patients with a new diagnosis of UC (27 South Asians; 15 Caucasians) with 261 biosamples. There were significant differences in relative abundance of bacteria at the phylum, genus and species level. Relative concentrations of urinary metabolites in South Asians were significantly lower for hippurate (positive correlation for Ruminococcus) and 4-cresol sulfate (Clostridia) (p<0.001) with higher concentrations of lactate (negative correlation for Bifidobacteriaceae). Faecal conjugated and primary conjugated bile acids concentrations were significantly higher in South Asians (p=0.02 and p=0.03 respectively). Results were unaffected by diet, phenotype, disease severity and ongoing therapy. Comparison of time points at diagnosis and at 1 year did not reveal changes in microbial and metabolic profile. Conclusion: Ethnic-related microbial metabolite associations were observed in South Asians with UC. This suggests a predisposition to UC may be influenced by environmental factors reflected in a distinct gene-environment interaction. The variations may serve as markers to identify risk factors for UC and modified to enhance therapeutic response
Mid-regional pro-adrenomedullin as a supplementary tool to clinical parameters in cases of suspicion of infection in the emergency department
Introduction: Mid-regional proadrenomedullin (MR-proADM), a novel biomarker, has recently gained interest particularly with regards to its potential in assisting clinicians\u2019 decision making in patients with suspicion of infection in the emergency department (ED). A group of international experts, with research and experience in MR-proADM applications, produced this review based on their own experience and the currently available literature. Areas covered: The review provides evidence related to MR-proADM as a triaging tool in avoiding unnecessary admissions to hospital and/or inadequate discharge, and identifying patients most at risk of deterioration. It also covers the use of MR-proADM in the context of COVID-19. Moreover, the authors provide a proposal on how to incorporate MR-proADM into patients\u2019 clinical pathways in an ED setting. Expert opinion: The data we have so far on the application of MR-proADM in the ED is promising. Incorporating it into clinical scoring systems may aid the clinician\u2019s decision making and recognizing the \u2018ill looking well\u2019 and the \u2018well looking ill\u2019 sooner. However there are still many gaps in our knowledge especially during the ongoing COVID-19 waves. There is also a need for cost-effectiveness analysis studies especially in the era of increasing cost pressures on health systems globally
Water hyacinth (Eichhornia crassipes) detection using coarse and high resolution multispectral data
Efficient detection and monitoring procedures of invasive plant species are required. It is of
crucial importance to deal with such plants in aquatic ecosystems, since they can affect biodiversity
and, ultimately, ecosystem function and services. In this study, it is intended to detect water hyacinth
(Eichhornia crassipes) using multispectral data with different spatial resolutions. For this purpose,
high-resolution data (<0.1 m) acquired from an unmanned aerial vehicle (UAV) and coarse-resolution
data (10 m) from Sentinel-2 MSI were used. Three areas with a high incidence of water hyacinth
located in the Lower Mondego region (Portugal) were surveyed. Different classifiers were used
to perform a pixel-based detection of this invasive species in both datasets. From the different
classifiers used, the results were achieved by the random forest classifiers stand-out (overall accuracy
(OA): 0.94). On the other hand, support vector machine performed worst (OA: 0.87), followed by
Gaussian naive Bayes (OA: 0.88), k-nearest neighbours (OA: 0.90), and artificial neural networks
(OA: 0.91). The higher spatial resolution from UAV-based data enabled us to detect small amounts of
water hyacinth, which could not be detected in Sentinel-2 data. However, and despite the coarser
resolution, satellite data analysis enabled us to identify water hyacinth coverage, compared well with
a UAV-based survey. Combining both datasets and even considering the different resolutions, it was
possible to observe the temporal and spatial evolution of water hyacinth. This approach proved to
be an effective way to assess the effects of the mitigation/control measures taken in the study areas.
Thus, this approach can be applied to detect invasive species in aquatic environments and to monitor
their changes over time.This research activity was funded by POCI-FEDER as part of the project âBioComp_2.0â
Produção de compostos orgânicos biológicos para o controlo do jacinto de ågua e para a valorização
de subprodutos agropecuĂĄrios, florestais e agroindustriaisâ (POCI-01-0247-FEDER-070123) and by
national funds through FCT (Portuguese Foundation for Science and Technology) under the projects
UIDB/04033/2020 and UIDB/00690/2020.info:eu-repo/semantics/publishedVersio
The Impact of Almonds and Almond Processing On Gastrointestinal Physiology, Luminal Microbiology and Gastrointestinal Symptoms: a Randomized Controlled Trial and Mastication Study.
BACKGROUND: Almonds contain lipid, fiber and polyphenols and possess physicochemical properties that impact nutrient bioaccessibility, which are hypothesized to impact gut physiology and microbiota. OBJECTIVES: Investigate the impact of whole almonds and ground almonds (almond flour) on fecal bifidobacteria (primary outcome), gut microbiota composition and transit time. DESIGN: Healthy adults (n = 87) participated in a parallel, 3-arm randomized controlled trial. Participants received whole almonds (56 g/d), ground almonds (56 g/d) or an isocaloric control muffin in place of habitual snacks for 4 weeks. Gut microbiota composition and diversity (16S rRNA gene sequencing), short-chain fatty acids (gas-chromatography), volatile organic compounds (gas-chromatography mass-spectrometry), gut transit time (wireless motility capsule), stool output and gut symptoms (7-day diary) were measured at baseline and endpoint. The impact of almond form on particle size distribution (PSD) and predicted lipid release was measured in a subgroup (n = 31). RESULTS: Modified intention-to-treat analysis was performed on 79 participants. There were no significant differences in abundance of fecal bifidobacteria following consumption of whole almonds (8.7%, SD 7.7%), ground almonds (7.8%, SD 6.9%) or control (13.0%, SD 10.2%; q = 0.613). Consumption of almonds (whole and ground pooled) resulted in higher butyrate (24.1 Οmol/g, SD 15.0 Οmol/g) in comparison to control (18.2 Οmol/g, SD 9.1 Οmol/g; p = 0.046). There was no effect of almonds on gut microbiota at the phylum level or diversity, gut transit time, stool consistency or gut symptoms. Almond form (whole versus ground) had no effect on study outcomes. Ground almonds resulted in significantly smaller PSD and higher predicted lipid release (10.4%, SD 1.8%) in comparison to whole almonds (9.3%, SD 2.0%; p = 0.017). CONCLUSIONS: Almond consumption has limited impact on gut microbiota composition but increases butyrate concentrations in adults, suggesting positive alterations to microbiota functionality. Almonds can be incorporated into the diet to increase fiber consumption without triggering gut symptoms. Clinical trial registry: ClinicalTrials.gov identifier - NCT03581812
Quantifying hydrofluoric acid etching of quartz and feldspar coarse grains based on weight loss estimates: implication for ESR and luminescence dating studies
A series of hydrofluoric (HF) acid etching experiments were performed on several 50 to 300 Îźm (nominal sieve opening) quartz and feldspar samples, and average etching thicknesses were subsequently determined from weight loss estimates, following the approach of Bell & Zimmerman (1978). Our results are consistent with previous studies and confirm that both HF experimental conditions (etching time, HF concentration, agitation) and the nature/origin of the minerals have a significant effect on etching rate and magnitude. For the samples considered in this study, the outer 10 Îźm of quartz (i.e., the usual etching target in most ESR and luminescence dating studies) was removed with 40% HF after 40 min of etching, in fair agreement with previous studies. Similar etching results were achieved in just over 20 min when the quartz samples were constantly agitated during 40% HF treatment. For K-feldspars, 10% HF etching for between 10 and 40 min was required to remove the same thickness, although some variability in etching efficiency was evident between different samples and experimental conditions. For a given experimental setup, the overall variability in etching thickness among quartz samples was found to be of at least 20% after 40â 60 min with 40% HF, and can be as high as âź35%. A set of 14 K-feldspars from a single site revealed an inherent variability of 14% in etching thickness. As a first order approximation, these data may provide useful insights into the expected variability among samples of different origin and from a given area, respectively. However, we recommend that each laboratory evaluates etching thickness losses for their specific HF experimental setup. Additionally, our results show that the 10 Îźm etching usually considered in ESR and luminescence dating studies may reduce the alpha contribution of the total dose rate to <5%. Although relatively small, this contribution is nevertheless non-negligible. Based on these results, it may be worth considering an additional alpha dose rate term as part of the ESR and luminescence age calculation when etching depths are < 15 Îźm.M. Duval, V. Guilarte, I. CampaĂąa, L.J. Arnold, L. Miguens, J. Iglesias, S. GonzĂ lez-Sierr
Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC
The uncertainty on the calorimeter energy response to jets of particles is
derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the
calorimeter response to single isolated charged hadrons is measured and
compared to the Monte Carlo simulation using proton-proton collisions at
centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009
and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter
response to specific types of particles (positively and negatively charged
pions, protons, and anti-protons) is measured and compared to the Monte Carlo
predictions. Finally, the jet energy scale uncertainty is determined by
propagating the response uncertainty for single charged and neutral particles
to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3%
for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table,
submitted to European Physical Journal
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
Standalone vertex ďŹnding in the ATLAS muon spectrometer
A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at âs = 7 TeV collected with the ATLAS detector at the LHC during 2011
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