933 research outputs found

    Dampening Host Sensing and Avoiding Recognition in Pseudomonas aeruginosa Pneumonia

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    Pseudomonas aeruginosa is an opportunistic pathogen and causes a wide range of acute and chronic infections. P. aeruginosa infections are kept in check by an effective immune surveillance in the healthy host, while any imbalance or defect in the normal immune response can manifest in disease. Invasive acute infection in the immunocompromised patients is mediated by potent extracellular and cell bound bacterial virulence factors. Life-threatening chronic infection in cystic fibrosis patients is maintained by pathogenic variants that contribute to evade detection and clearance by the immune system. Here, we reviewed the molecular basis of receptor-mediated recognition of P. aeruginosa and their role in initiating inflammation and the colonization. In addition, the consequence of the P. aeruginosa genetic adaptation for the antibacterial defence and the maintaining of chronic infection are discussed

    Lo scoutismo: profilo storico e dispositivo pedagogico di un movimento educativo

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    Il saggio esamina le origini storiche dello scautismo e i suoi principali fondamenti pedagogici

    Aortic stenting in the growing sheep causes aortic endothelial dysfunction but not hypertension: Clinical implications for coarctation repair

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    Stent implantation is the treatment of choice for adolescents and adults with aortic coarctation (CoAo). Despite excellent short-term results, 20%-40% of the patients develop arterial hypertension later in life, which was attributed to inappropriate response of the aortic baroreceptors to increased stiffness of the ascending aorta (ASAO), either congenital or induced by CoAo repair. In particular, it has been hypothesized that stent itself may cause or sustain hypertension. Therefore, we aimed to study the hemodynamic and structural impact following stent implantation in the normal aorta of a growing animal

    Multiwavelength monitoring of a very active dwarf nova AX J1549.8-5416 with an unusually high duty cycle

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    We present new optical, UV and X-ray observations of a highly variable dwarf nova(DN) AX J1549.8-5416. The multiwavelength analysis of three mini-outbursts and one normal outburst represent one of the most complete multiwavelength studies of a DN and help to refine the relationship between the X-ray, UV and optical emission in this system. We find that the UV emission is delayed the optical (1.0-5.4 days) during the rising phase of the outburst. The X-ray emission is suppressed during the peak of the optical outburst and recovers during the end of the outburst. We also analyse archival Swift, Chandra and XMM-Newton observations of the source. Our estimated high duty cycle suggests the X-ray luminosity of this source should be larger than 10E32 erg/s in quiescence. We find a roughly anti-correlation between X-ray and UV flux. The X-ray spectra of XMM-Newton and Chandra can be well described either by a single temperature thermal plasma model or by an isobaric cooling flow model when its X-ray flux is high.Fil: Zhang, Guobao. New York University Abu Dhabi; Emiratos Arabes UnidosFil: Gelfand, Joseph D.. New York University Abu Dhabi; Emiratos Arabes UnidosFil: Russell, David M.. New York University Abu Dhabi; Emiratos Arabes UnidosFil: Lewis, Fraser. Cardiff University; Reino UnidoFil: Masetti, Nicola. Istituto Nazionale di Astrofisica; ItaliaFil: Bernardini, Federico. New York University Abu Dhabi; Emiratos Arabes UnidosFil: Andruchow, Ileana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Zibecchi, Lorena Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaThe X-ray Universe 2017RomaItaliaEuropean Space AgencyXMM Newton Science CenterNational Institute for AstrophysicsItalian Space AgencyUniversity Roma TreLa Sapienza Universit

    Multiwavelength monitoring of a very active dwarf nova AX J1549.8-5416 with an unusually high duty cycle

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    We present the results of our analysis of new optical, ultraviolet (UV) and X-ray observations of a highly variable source − AX J1549.8−5416. Both the detection of several fast rise, exponential decay outbursts in the optical light curve and the lack of He II emission lines in the optical spectra suggest AX J1549.8−5416 is a cataclysmic variable of the dwarf nova (DN) type. The multiwavelength analysis of three mini-outbursts and one normal outburst represent one of the most complete multiwavelength studies of a DN and help to refine the relationship between the X-ray, UV and optical emission in this system. We find that the UV emission is delayed with respect to the optical by 1.0–5.4 d during the rising phase of the outburst. The X-ray emission is suppressed during the peak of the optical outburst and recovers during the end of the outburst. From our analysis of archival Swift, Chandra and XMM–Newton observations of AX J1549.8−5416, we estimate this DN has a high duty cycle (∼50 per cent), suggesting a quiescent X-ray luminosity larger than 1032 erg/s. We also find the X-ray and UV flux are roughly anticorrelated. Furthermore, we find that, at low X-ray fluxes, the X-ray spectrum is well described by a single temperature thermal plasma model, while at high X-ray fluxes, an isobaric cooling flow model also works. We find that the maximum temperature of the plasma in quiescence is significantly higher than that in outburst.Instituto de Astrofísica de La Plat

    Multiwavelength monitoring of a very active dwarf nova AX J1549.8-5416 with an unusually high duty cycle

    Get PDF
    We present the results of our analysis of new optical, ultraviolet (UV) and X-ray observations of a highly variable source − AX J1549.8−5416. Both the detection of several fast rise, exponential decay outbursts in the optical light curve and the lack of He II emission lines in the optical spectra suggest AX J1549.8−5416 is a cataclysmic variable of the dwarf nova (DN) type. The multiwavelength analysis of three mini-outbursts and one normal outburst represent one of the most complete multiwavelength studies of a DN and help to refine the relationship between the X-ray, UV and optical emission in this system. We find that the UV emission is delayed with respect to the optical by 1.0–5.4 d during the rising phase of the outburst. The X-ray emission is suppressed during the peak of the optical outburst and recovers during the end of the outburst. From our analysis of archival Swift, Chandra and XMM–Newton observations of AX J1549.8−5416, we estimate this DN has a high duty cycle (∼50 per cent), suggesting a quiescent X-ray luminosity larger than 1032 erg/s. We also find the X-ray and UV flux are roughly anticorrelated. Furthermore, we find that, at low X-ray fluxes, the X-ray spectrum is well described by a single temperature thermal plasma model, while at high X-ray fluxes, an isobaric cooling flow model also works. We find that the maximum temperature of the plasma in quiescence is significantly higher than that in outburst.Instituto de Astrofísica de La Plat

    Flora and plant communities across a complex network of heavily modified water bodies: geographical patterns, land use and hydrochemical drivers in a temperate overexploited plain

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    The decline of freshwater flora due to alteration, reclamation and trophic perturbation of lowland wetlands is among the most relevant issues in biological conservation. The contribution of heavily modified water bodies (HMWBs) in preserving plant diversity is notable, but the underlying ecological mechanisms are not completely explored. To contribute to this debate and expand the knowledge on the role of HMWBs in maintaining wetland biodiversity in overexploited agroecosystems, a canal network of about 1150 km (SE Po valley, N-Italy) was analysed to study the geographical patterns of riparian flora and plant communities, and their land use and hydrochemical drivers. A systematic sampling procedure was adopted by randomly selecting 96 transects (10 ­m 2 ) along 79 drainage canals. Additionally, 22 transects were sampled for water quality evaluation. Flora was characterised based on species richness and presence of threatened, alien and invasive species. We also studied the contribution of land use and water quality in explaining plant richness and composition. Slope and aspect of canals do not significantly affect plant species composition, whereas the «proximity to protected areas» seems to have a negative influence. Both threatened and alien plants richness decrease approaching protected areas. Among land use types, only agro-zootechnical settlements influence plant species composition, favoring nitrophilous species, as demonstrated by water parameters (the spatial patterns of nitrophilous species mirrored the progressive worsening of canal waters). This work confirms the key role of HMWBs in sustaining plant species diversity in oversimplified landscapes, highlighting complex regulation mechanisms that need further investigations

    Monitoring of Bright Blazars with MAGIC in the 2007/2008 Season

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    Because of the short duty-cycles and observation-time constraints, studies of bright TeV (E>100 GeV) blazars are mostly restricted to flaring episodes or rather short (days to few weeks) multiwavelength campaigns. At the same time, long-term studies of these objects are essential to gain a more complete understanding of the blazar phenomenon and to constrain theoretical models concerning jet physics. Only unbiased long-term studies are adequate for the determination of flaring state probabilities and for estimating the statistical significance of possible correlations between TeV flaring states and other wavebands or observables, such as neutrino events. Regular observations also provide triggers for multiwavelength ToO observations originating from the TeV waveband. These are particularly needed to identify and study orphan TeV flares, i.e. flares without counterparts in other wavebands. In 2007/8 the MAGIC telescope has monitored three TeV blazars on a regular basis: Mrk 501, Mrk 421, and 1ES 1959+650. We present preliminary results of these observations including the measured light curves and a correlation study for VHE gamma-rays and X-rays and VHE gamma-rays and optical R-band for Mrk 421.Comment: 10 pages, 7 figures, Proceedings of the SciNEGHE'0
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