105 research outputs found

    Multi-modal probabilistic indoor localization on a smartphone

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    The satellite-based Global Positioning System (GPS) provides robust localization on smartphones outdoors. In indoor environments, however, no system is close to achieving a similar level of ubiquity, with existing solutions offering different trade-offs in terms of accuracy, robustness and cost. In this paper, we develop a multi-modal positioning system, targeted at smartphones, which aims to get the best out of each of its constituent modalities. More precisely, we combine Bluetooth low energy (BLE) beacons, round-trip-time (RTT) enabled WiFi access points and the smartphone’s inertial measurement unit (IMU) to provide a cheap robust localization system that, unlike fingerprinting methods, requires no pre-training. To do this, we use a probabilistic algorithm based on a conditional random field (CRF). We show how to incorporate sparse visual information to improve the accuracy of our system, using pose estimation from pre-scanned visual landmarks, to calibrate the system online. Our method achieves an accuracy of around 2 meters on two realistic datasets, outperforming other distance-based localization approaches. We also compare our approach with an ultra-wideband (UWB) system. While we do not match the performance of UWB, our system is cheap, smartphone compatible and provides satisfactory performance for many applications

    Innate immunity: ignored for decades, but not forgotten.

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    The innate immune system must recognize and rapidly respond to microbial pathogens, providing a first line of host defense. This is accomplished through an array of pattern recognition receptors (PRRs) that reside in specific subcellular compartments and can bind pathogen-associated molecular patterns. PRRs also recognize self-molecules that are released after cell damage or death, known as danger-associated molecular patterns, which can be actively transported across cell membranes. The activation of PRRs leads to host defense pathways in infectious diseases, but can also contribute to tissue injury in autoimmune diseases. The identification of these pathways has provided new insight into mechanisms of vaccination and holds promise for developing better vaccines. Finally, the identification of PRRs, their ligands, and signaling pathways provides an opportunity for developing new immunotherapeutic approaches to skin conditions in which activation of the innate immune response contributes to disease pathogenesis

    Paleofire reconstruction based on an ensemble-member strategy applied to sedimentary charcoal

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    Paleofire events obtained from the statistical treatment of sedimentary charcoal records rely on a number of assumptions and user's choices, increasing the uncertainty of reconstructio\ns. Among the assumptions made when analyzing charcoal series is the choice of a filtering method for raw Charcoal Accumulation Rate (CHARraw). As there is no ultimate CHAR raw filtering method, we propose an ensemble-member approach to reconstruct fire events. We modified the commonly used procedure by including a routine replicating the analysis of a charcoal record using custom smoothing parameters. Dates of robust fire events, uncertainties in fire-return intervals and fire frequencies are derived from members' distributions. An application of the method is used to quantify uncertainties due to data treatment in two CHARraw sequences from two different biomes, subalpine and boreal

    Consistency in Polyclonal T-cell Responses to Gluten between Children and Adults with Celiac Disease

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    BACKGROUND & AIMS: Developing antigen-specific approaches for diagnosis and treatment of celiac disease requires a detailed understanding of the specificity of T cells for gluten. The existing paradigm is that T-cell lines and clones from children differ from those of adults in the hierarchy and diversity of peptide recognition. We aimed to characterize the T-cell response to gluten in children vs adults with celiac disease. METHODS: Forty-one children with biopsy-proven celiac disease (median age, 9 years old; 17 male), who had been on strict gluten-free diets for at least 3 months, were given a 3-day challenge with wheat; blood samples were collected and gluten-specific T cells were measured. We analyzed responses of T cells from these children and from 4 adults with celiac disease to a peptide library and measured T-cell receptor bias. We isolated T-cell clones that recognized dominant peptides and assessed whether gluten peptide recognition was similar between T-cell clones from children and adults. RESULTS: We detected gluten-specific responses by T cells from 30 of the children with celiac disease (73%). T cells from the children recognized the same peptides that were immunogenic to adults with celiac disease; deamidation of peptides increased these responses. Age and time since diagnosis did not affect the magnitude of T-cell responses to dominant peptides. T-cell clones specific for dominant α- or ω-gliadin peptides from children with celiac disease had comparable levels of reactivity to wheat, rye, and barley peptides as T-cell clones from adults with celiac disease. The α-gliadin-specific T cells from children had biases in T-cell receptor usage similar to those in adults. CONCLUSIONS: T cells from children with celiac disease recognize similar gluten peptides as T cells from adults with celiac disease. The findings indicate that peptide-based diagnostics and therapeutics for adults may also be used for children. Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved

    Coherent signature of warming-induced extreme sub-continental boreal wildfire activity 4800 and 1100 years BP

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    Climate changes are expected to progressively increase extreme wildfire frequency in forests. Finding past analogs for periods of extreme biomass burning would provide valuable insights regarding what the effects of warming might be for tree species distribution, ecosystem integrity, atmospheric greenhouse gas balance, and human safety. Here, we used a network of 42 lake-sediment charcoal records across a ~2000 km transect in eastern boreal North America to infer widespread periods of wildfire activity in association with past climate conditions. The reconstructed fluctuations in biomass burning are broadly consistent with variations in ethane concentration in Greenland polar ice cores. Biomass burning fluctuations also significantly co-varied with Greenland temperatures estimated from ice cores, at least for the past 6000 years. Our retrospective analysis of past fire activity allowed us to identify two fire periods centered around 4800 and 1100 BP, coinciding with large-scale warming in northern latitudes and having respectively affected an estimated ~71% and ~57% of the study area. These two periods co-occurred with widespread decreases in mean fire-return intervals. The two periods are likely the best analogs for what could be anticipated in terms of impacts of fire on ecosystem services provided by these forests in coming decades

    A Commensal Helicobacter sp. of the Rodent Intestinal Flora Activates TLR2 and NOD1 Responses in Epithelial Cells

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    Helicobacter spp. represent a proportionately small but significant component of the normal intestinal microflora of animal hosts. Several of these intestinal Helicobacter spp. are known to induce colitis in mouse models, yet the mechanisms by which these bacteria induce intestinal inflammation are poorly understood. To address this question, we performed in vitro co-culture experiments with mouse and human epithelial cell lines stimulated with a selection of Helicobacter spp., including known pathogenic species as well as ones for which the pathogenic potential is less clear. Strikingly, a member of the normal microflora of rodents, Helicobacter muridarum, was found to be a particularly strong inducer of CXC chemokine (Cxcl1/KC, Cxcl2/MIP-2) responses in a murine intestinal epithelial cell line. Time-course studies revealed a biphasic pattern of chemokine responses in these cells, with H. muridarum lipopolysaccharide (LPS) mediating early (24–48 h) responses and live bacteria seeming to provoke later (48–72 h) responses. H. muridarum LPS per se was shown to induce CXC chemokine production in HEK293 cells stably expressing Toll-like receptor 2 (TLR2), but not in those expressing TLR4. In contrast, live H. muridarum bacteria were able to induce NF-ÎșB reporter activity and CXC chemokine responses in TLR2–deficient HEK293 and in AGS epithelial cells. These responses were attenuated by transient transfection with a dominant negative construct to NOD1, and by stable expression of NOD1 siRNA, respectively. Thus, the data suggest that both TLR2 and NOD1 may be involved in innate immune sensing of H. muridarum by epithelial cells. This work identifies H. muridarum as a commensal bacterium with pathogenic potential and underscores the potential roles of ill-defined members of the normal flora in the initiation of inflammation in animal hosts. We suggest that H. muridarum may act as a confounding factor in colitis model studies in rodents

    Antibiotics for acute pyelonephritis in children

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    Background Urinary tract infection (UTI) is one of the most common bacterial infections in infants. The most severe form of UTI is acute pyelonephritis, which results in significant acute morbidity and may cause permanent kidney damage. There remains uncertainty regarding the optimum antibiotic regimen, route of administration and duration of treatment. This is an update of a review that was first published in 2003 and updated in 2005 and 2007. Objectives To evaluate the benefits and harms of antibiotics used to treat children with acute pyelonephritis. The aspects of therapy considered were 1) different antibiotics, 2) different dosing regimens of the same antibiotic, 3) different duration of treatment, and 4) different routes of administration. Search methods We searched the Cochrane Renal Group's Specialised Register, CENTRAL, MEDLINE, EMBASE, reference lists of articles and conference proceedings without language restriction to 10 April 2014. Selection criteria Randomised and quasi‐randomised controlled trials comparing different antibiotic agents, routes, frequencies or durations of therapy in children aged 0 to 18 years with proven UTI and acute pyelonephritis were selected. Data collection and analysis Four authors independently assessed study quality and extracted data. Statistical analyses were performed using the random‐effects model and the results expressed as risk ratio (RR) for dichotomous outcomes or mean difference (MD) for continuous data with 95% confidence intervals (CI). Main results This updated review included 27 studies (4452 children). This update included evidence from three new studies, and following re‐evaluation, a previously excluded study was included because it now met our inclusion criteria. Risk of bias was assessed as low for sequence generation (12 studies), allocation concealment (six studies), blinding of outcome assessors (17 studies), incomplete outcome reporting (19 studies) and selective outcome reporting (13 studies). No study was blinded for participants or investigators. The 27 included studies evaluated 12 different comparisons. No significant differences were found in duration of fever (2 studies, 808 children: MD 2.05 hours, 95% CI ‐0.84 to 4.94), persistent UTI at 72 hours after commencing therapy (2 studies, 542 children: RR 1.10, 95% CI 0.07 to 17.41) or persistent kidney damage at six to 12 months (4 studies, 943 children: RR 0.82, 95% CI 0.59 to 1.12) between oral antibiotic therapy (10 to 14 days) and intravenous (IV) therapy (3 days) followed by oral therapy (10 days). Similarly, no significant differences in persistent bacteriuria at the end of treatment (4 studies, 305 children: RR 0.78, 95% CI 0.24 to 2.55) or persistent kidney damage (4 studies, 726 children: RR 1.01, 95% CI 0.80 to 1.29) were found between IV therapy (three to four days) followed by oral therapy and IV therapy (seven to 14 days). No significant differences in efficacy were found between daily and thrice daily administration of aminoglycosides (1 study, 179 children, persistent clinical symptoms at three days: RR 1.98, 95% CI 0.37 to 10.53). Adverse events were mild and uncommon and rarely resulted in discontinuation of treatment. Authors' conclusions This updated review increases the body of evidence that oral antibiotics alone are as effective as a short course (three to four days) of IV antibiotics followed by oral therapy for a total treatment duration of 10 to 14 days for the treatment of acute pyelonephritis in children. When IV antibiotics are given, a short course (two to four days) of IV therapy followed by oral therapy is as effective as a longer course (seven to 10 days) of IV therapy. If IV therapy with aminoglycosides is chosen, single daily dosing is safe and effective. Insufficient data are available to extrapolate these findings to children aged less than one month of age or to children with dilating vesicoureteric reflux (grades III‐V). Further studies are required to determine the optimal total duration of antibiotic therapy required for acute pyelonephritis
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