735 research outputs found

    Tree species diversity estimation using airborne imaging spectroscopy

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    With the ongoing global biodiversity loss, approaches to measuring and monitoring biodiversity are necessary for effective conservation planning, especially in tropical forests. Remote sensing is a very potential tool for biodiversity mapping, and high spatial resolution imaging spectroscopy allows for direct estimation of tree species diversity based on spectral reflectance. The objective of this study is to test an approach for estimating tree species alpha diversity in a tropical montane forest in the Taita Hills, Kenya. Tree species diversity is estimated based on spectral variation of high spatial resolution imaging spectroscopy data. The approach is an unsupervised classification, or clustering, applied to objects that represent tree crowns. Airborne imaging spectroscopy data and species data from 31 field plots were collected from the study area. After preprocessing of the spectroscopic imagery, a minimum noise fraction (MNF) transformation with a subsequent selection of 13 bands was applied to the data to reduce its noise and dimensionality. The imagery was then segmented to obtain objects that represent tree crowns. A clustering algorithm was applied to the segments, with the aim of grouping spectrally similar tree crowns. Experiments were made to find the optimal range for the number of clusters. Tree species richness and two diversity indices were calculated from the field data and from the clustering results. The clusters were assumed to represent species in the calculations. Correlation analysis and linear regression analysis were used to study the relationship between diversity measures from the field data and from the clustering results. It was found that the approach succeeded well in revealing tree species diversity patterns with all three diversity measures. Despite some factors that added error to the relationship between field-derived and clustering-derived diversity measures, high correlations were observed. Especially tree species richness could be modelled well using the approach (standard error: 3 species). The size of the considered trees was found to be an important determinant of the relationships. Finally, a tree species richness map was created for the study area. With further development, the presented approach has potential for other interesting applications, such as estimation of beta diversity, and tree species identification by linking the reflectance properties of individual crowns to their corresponding species.Luonnon monimuotoisuuden maailmanlaajuisen vĂ€henemisen vuoksi biodiversiteetin mittaus- ja tarkkailumenetelmiĂ€ tarvitaan tehokkaaseen suojelualueiden suunnitteluun, erityisesti trooppisissa metsissĂ€. Kaukokartoitus on erittĂ€in lupaava vĂ€line biodiversiteetin kartoitukseen, ja spatiaalisesti tarkka hyperspektraalinen aineisto (kuvantava spektroskopia) mahdollistaa puiden lajidiversiteetin arvioinnin suoraan niiden spektraalisen heijastuksen perusteella. TĂ€mĂ€n tutkimuksen tarkoitus on kokeilla lĂ€hestymistapaa puulajien alfadiversiteetin mittaamiseen trooppisessa vuoristometsĂ€ssĂ€ Kenian Taitavuorilla. Puulajien monimuotoisuutta arvioidaan spatiaalisesti tarkan hyperspektraalisen aineiston heijastuksen vaihtelun avulla. LĂ€hestymistapa on puunlatvuksia edustaville kohteille tehty ohjaamaton luokittelu, tarkemmin ilmaistuna klusterointi. Tutkimusalueelta kerĂ€ttiin hyperspektraalista ilmakuva-aineistoa sekĂ€ puulajitiedot 31 maastokoealalta. Hyperspektraalisen aineiston esikĂ€sittelyn jĂ€lkeen sen hĂ€lyĂ€ ja ulottuvuuksia vĂ€hennettiin tekemĂ€llĂ€ sille MNF (minimum noise fraction) –muunnos ja valitsemalla 13 parasta kanavaa. TĂ€mĂ€n jĂ€lkeen ilmakuva segmentoitiin puunlatvuksia kuvaaviksi kohteiksi. Kohteet klusteroitiin klusterointialgoritmia kĂ€yttĂ€en, tarkoituksena ryhmitellĂ€ spektraalisesti samankaltaiset puunlatvukset. Ihanteellisen klusterimÀÀrĂ€n löytĂ€miseksi tehtiin kokeiluja. Puulajirunsaus ja kaksi diversiteetti-indeksiĂ€ laskettiin maastoaineistolle ja klusteroinnin tuloksille. Klustereiden oletettiin edustavan puulajeja laskelmissa. Maastoaineistosta ja klusterointituloksista laskettujen diversiteettimittareiden suhdetta tutkittiin korrelaatioanalyysin ja lineaarisen regressioanalyysin avulla. LĂ€hestymistapaa soveltaen onnistuttiin hyvin paljastamaan puulajien monimuotoisuuden piirteitĂ€ kaikkien kolmen diversiteettimittarin avulla. Huolimatta tekijöistĂ€, jotka aiheuttivat virhettĂ€ maastoaineistoon ja klusterointituloksiin perustuvien diversiteettimittareiden suhteeseen, korrelaatioasteet olivat korkeita. Varsinkin puiden lajirunsautta pystyttiin mallintamaan hyvin lĂ€hestymistavan avulla (keskivirhe: kolme lajia). Mukaanluettujen puiden koko oli tĂ€rkeĂ€ tekijĂ€ muuttujien suhteissa. Lopuksi tehtiin kartta puulajirunsaudesta tutkimusalueelle. JatkokehittĂ€misen avulla esitellyllĂ€ lĂ€hestymistavalla on mahdollisuuksia muihinkin mielenkiintoisiin sovelluksiin, kuten betadiversiteetin arvioimiseen, sekĂ€ puulajien tunnistukseen, kun yksittĂ€isten latvusten heijastusominaisuudet liitetÀÀn niitĂ€ vastaaviin lajeihin

    Validation of the Remote Automated ki:e Speech Biomarker for Cognition in Mild Cognitive Impairment:Verification and Validation following DiME V3 Framework

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    INTRODUCTION: Progressive cognitive decline is the cardinal behavioral symptom in most dementia-causing diseases such as Alzheimer's disease. While most well-established measures for cognition might not fit tomorrow's decentralized remote clinical trials, digital cognitive assessments will gain importance. We present the evaluation of a novel digital speech biomarker for cognition (SB-C) following the Digital Medicine Society's V3 framework: verification, analytical validation, and clinical validation. METHODS: Evaluation was done in two independent clinical samples: the Dutch DeepSpA (N = 69 subjective cognitive impairment [SCI], N = 52 mild cognitive impairment [MCI], and N = 13 dementia) and the Scottish SPeAk datasets (N = 25, healthy controls). For validation, two anchor scores were used: the Mini-Mental State Examination (MMSE) and the Clinical Dementia Rating (CDR) scale. RESULTS: Verification: The SB-C could be reliably extracted for both languages using an automatic speech processing pipeline. Analytical Validation: In both languages, the SB-C was strongly correlated with MMSE scores. Clinical Validation: The SB-C significantly differed between clinical groups (including MCI and dementia), was strongly correlated with the CDR, and could track the clinically meaningful decline. CONCLUSION: Our results suggest that the ki:e SB-C is an objective, scalable, and reliable indicator of cognitive decline, fit for purpose as a remote assessment in clinical early dementia trials

    Recognition of microbial viability via TLR8 drives TFH cell differentiation and vaccine responses

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    Live attenuated vaccines are generally highly efficacious and often superior to inactivated vaccines, yet the underlying mechanisms of this remain largely unclear. Here we identify recognition of microbial viability as a potent stimulus for follicular helper T cell (TFH cell) differentiation and vaccine responses. Antigen-presenting cells (APCs) distinguished viable bacteria from dead bacteria through Toll-like receptor 8 (TLR8)-dependent detection of bacterial RNA. In contrast to dead bacteria and other TLR ligands, live bacteria, bacterial RNA and synthetic TLR8 agonists induced a specific cytokine profile in human and porcine APCs, thereby promoting TFH cell differentiation. In domestic pigs, immunization with a live bacterial vaccine induced robust TFH cell and antibody responses, but immunization with its heat-killed counterpart did not. Finally, a hypermorphic TLR8 polymorphism was associated with protective immunity elicited by vaccination with bacillus Calmette-GuĂ©rin (BCG) in a human cohort. We have thus identified TLR8 as an important driver of TFH cell differentiation and a promising target for TFH cell–skewing vaccine adjuvants

    Hybrid cosmic ray measurements using the IceAct telescopes in coincidence with the IceCube and IceTop detectors

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    IceAct is a proposed surface array of compact (50 cm diameter) and cost-effective Imaging Air Cherenkov Telescopes installed at the site of the IceCube Neutrino Observatory at the geographic South Pole. Since January 2019, two IceAct telescope demonstrators, featuring 61 silicon photomultiplier (SiPM) pixels have been taking data in the center of the IceTop surface array during the austral winter. We present the first analysis of hybrid cosmic ray events detected by the IceAct imaging air-Cherenkov telescopes in coincidence with the IceCube Neutrino Observatory, including the IceTop surface array and the IceCube in-ice array. By featuring an energy threshold of about 10 TeV and a wide field-of-view, the IceAct telescopes show promising capabilities of improving current cosmic ray composition studies: measuring the Cherenkov light emissions in the atmosphere adds new information about the shower development not accessible with the current detectors, enabling significantly better primary particle type discrimination on a statistical basis. The hybrid measurement also allows for detailed feasibility studies of detector cross-calibration and of cosmic ray veto capabilities for neutrino analyses. We present the performance of the telescopes, the results from the analysis of two years of data, and an outlook of a hybrid simulation for a future telescope array

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

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    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

    Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

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    BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≄week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

    Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

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    Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (Ό̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ÂŻ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ÂŻ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),Ό̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

    Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

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    Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≄ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

    Measurement of b jet shapes in proton-proton collisions at root s=5.02 TeV

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    We present the first study of charged-hadron production associated with jets originating from b quarks in proton-proton collisions at a center-of-mass energy of 5.02 TeV. The data sample used in this study was collected with the CMS detector at the CERN LHC and corresponds to an integrated luminosity of 27.4 pb(-1). To characterize the jet substructure, the differential jet shapes, defined as the normalized transverse momentum distribution of charged hadrons as a function of angular distance from the jet axis, are measured for b jets. In addition to the jet shapes, the per-jet yields of charged particles associated with b jets are also quantified, again as a function of the angular distance with respect to the jet axis. Extracted jet shape and particle yield distributions for b jets are compared with results for inclusive jets, as well as with the predictions from the pythia and herwig++ event generators.Peer reviewe

    Measurement of the azimuthal anisotropy of Y(1S) and Y(2S) mesons in PbPb collisions at root s(NN)=5.02 TeV

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    The second-order Fourier coefficients (v(2)) characterizing the azimuthal distributions of Y(1S) and Y(2S) mesons produced in PbPb collisions at root s(NN) = 5.02 TeV are studied. The Y mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The collected data set corresponds to an integrated luminosity of 1.7 nb(-1). The scalar product method is used to extract the v2 coefficients of the azimuthal distributions. Results are reported for the rapidity range vertical bar y vertical bar < 2.4, in the transverse momentum interval 0 < pT < 50 GeV/c, and in three centrality ranges of 10-30%, 30-50% and 50-90%. In contrast to the J/psi mesons, the measured v(2) values for the Y mesons are found to be consistent with zero. (C) 2021 The Author(s). Published by Elsevier B.V.Peer reviewe
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