890 research outputs found

    Curves on Heisenberg invariant quartic surfaces in projective 3-space

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    This paper is about the family of smooth quartic surfaces XP3X \subset \mathbb{P}^3 that are invariant under the Heisenberg group H2,2H_{2,2}. For a very general such surface XX, we show that the Picard number of XX is 16 and determine its Picard group. It turns out that the general Heisenberg invariant quartic contains 320 smooth conics and that in the very general case, this collection of conics generates the Picard group.Comment: Updated references, corrected typo

    Pathophysiology and diagnostic approach to laryngomalacia in infants

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    SummaryLaryngomalacia is defined as collapse of supraglottic structures during inspiration. It is the most common laryngeal disease of infancy. Laryngomalacia presents in the form of stridor, a high-pitched, musical, vibrating, multiphase inspiratory noise appearing within the first 10 days of life. Signs of severity are present in 10% of cases: poor weight gain (probably the most contributive element), dyspnoea with permanent and severe intercostal or xyphoid retraction, episodes of respiratory distress, obstructive sleep apnoea, and/or episodes of suffocation while feeding or feeding difficulties. The diagnosis is based on systematic office flexible laryngoscopy to confirm laryngomalacia and exclude other causes of supraglottic obstruction. Rigid endoscopy under general anaesthesia is only performed in the following cases: absence of laryngomalacia on flexible laryngoscopy, presence of laryngomalacia with signs of severity, search for any associated lesions prior to surgery, discrepancy between the severity of symptoms and the appearance on flexible laryngoscopy, and/or atypical symptoms (mostly aspirations). The work-up must be adapted to each child; however, guidelines recommend objective respiratory investigations in infants presenting signs of severity

    Using multi-scale distribution and movement effects along a montane highway to identify optimal crossing locations for a large-bodied mammal community

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    Roads are a major cause of habitat fragmentation that can negatively affect many mammal populations. Mitigation measures such as crossing structures are a proposed method to reduce the negative effects of roads on wildlife, but the best methods for determining where such structures should be implemented, and how their effects might differ between species in mammal communities is largely unknown. We investigated the effects of a major highway through south-eastern British Columbia, Canada on several mammal species to determine how the highway may act as a barrier to animal movement, and how species may differ in their crossing-area preferences. We collected track data of eight mammal species across two winters, along both the highway and pre-marked transects, and used a multi-scale modeling approach to determine the scale at which habitat characteristics best predicted preferred crossing sites for each species. We found evidence for a severe barrier effect on all investigated species. Freely-available remotely-sensed habitat landscape data were better than more costly, manually-digitized microhabitat maps in supporting models that identified preferred crossing sites; however, models using both types of data were better yet. Further, in 6 of 8 cases models which incorporated multiple spatial scales were better at predicting preferred crossing sites than models utilizing any single scale. While each species differed in terms of the landscape variables associated with preferred/avoided crossing sites, we used a multi-model inference approach to identify locations along the highway where crossing structures may benefit all of the species considered. By specifically incorporating both highway and off-highway data and predictions we were able to show that landscape context plays an important role for maximizing mitigation measurement efficiency. Our results further highlight the need for mitigation measures along major highways to improve connectivity between mammal populations, and illustrate how multi-scale data can be used to identify preferred crossing sites for different species within a mammal community

    Using VO tools to investigate distant radio starbursts hosting obscured AGN in the HDF(N) region

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    A 10-arcmin field around the HDF(N) contains 92 radio sources >40 uJy, resolved by MERLIN+VLA at 0".2-2".0 resolution. 55 have Chandra X-ray counterparts including 18 with a hard X-ray photon index and high luminosity characteristic of a type-II (obscured) AGN. >70% of the radio sources have been classified as starbursts or AGN using radio morphologies, spectral indices and comparisons with optical appearance and MIR emission. Starbursts outnumber radio AGN 3:1. This study extends the VO methods previously used to identify X-ray-selected obscured type-II AGN to investigate whether very luminous radio and X-ray emission originates from different phenomena in the same galaxy. The high-redshift starbursts have typical sizes of 5--10 kpc and star formation rates of ~1000 Msun/yr. There is no correlation between radio and X-ray luminosities nor spectral indices at z>~1.3. ~70% of both the radio-selected AGN and the starburst samples were detected by Chandra. The X-ray luminosity indicates the presence of an AGN in at least half of the 45 cross-matched radio starbursts, of which 11 are type-II AGN including 7 at z>1.5. This distribution overlaps closely with the X-ray detected radio sources which were also detected by SCUBA. Stacked 1.4-GHz emission at the positions of radio-faint X-ray sources is correlated with X-ray hardness. Most extended radio starbursts at z>1.3 host X-ray selected obscured AGN. Radio emission from most of these ultra-luminous objects is dominated by star formation but it contributes less than 1/3 of their X-ray luminosity. Our results support the inferences from SCUBA and IR data, that at z>1.5, star formation is an order of magnitude more extended and more copious, it is closely linked to AGN activity and it is triggered differently, compared with star formation at lower redshifts.Comment: 24 pages, 12 figures, uses graphicx, rotating, natbib, supertabular packages and aa.cls. Accepted for publication in A&

    Involvement of Src Family Tyrosine Kinase in Apoptosis of Human Neutrophils Induced by Protozoan Parasite Entamoeba histolytica

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    Tyrosine kinases are one of the most important regulators for intracellular signal transduction related to inflammatory responses. However, there are no reports describing the effects of tyrosine kinases on neutrophil apoptosis induced by Entamoeba histolytica. In this study, isolated human neutrophils from peripheral blood were incubated with live trophozoites in the presence or absence of tyrosine kinase inhibitors. Entamoeba-induced receptor shedding of CD16 and PS externalization in neutrophils were inhibited by pre-incubation of neutrophils with the broad-spectrum tyrosine kinase inhibitor genistein or the Src family kinase inhibitor PP2. Entamoeba-induced ROS production was also inhibited by genistein or PP2. Moreover, genistein and PP2 blocked the phosphorylation of ERK and p38 MAPK in neutrophils induced by E. histolytica. These results suggest that Src tyrosine kinases may participate in the signaling event for ROS-dependent activation of MAPKs during neutrophil apoptosis induced by E. histolytica

    Effects of the SGLT-2 inhibitor dapagliflozin on glomerular and tubular injury markers

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    The mechanisms by which SGLT-2 inhibitors lower albuminuria are incompletely understood. We assessed in a post-hoc analysis of a cross-over trial the effects of the SGLT2 inhibitor dapagliflozin on glomerular markers (IgG to IgG4 and IgG to albumin), tubular markers (urinary KIM-1, NGAL and LFABP) and inflammatory markers (urinary MCP-1 and IL-6) to provide more insight into kidney protective effects. Dapagliflozin decreased albuminuria by 43.9% (95% CI, 30.3%-54.8%) and eGFR by 5.1 (2.0-8.1) mL/min/1.73m2 compared to placebo. Dapagliflozin did not change glomerular charge or size selectivity index compared to placebo. Dapagliflozin decreased urinary KIM-1 excretion by 22.6% (0.3%-39.8%; P = .05) and IL-6 excretion by 23.5% (1.4%-40.6%; P = .04) compared to placebo, whereas no changes in NGAL, LFABP and MCP-1 were observed. During dapagliflozin treatment, changes in albuminuria correlated with changes in eGFR (r = 0.36; P = .05) and KIM-1 (r = 0.39; P = .05). In conclusion, the albuminuria-lowering effect of 6 weeks of dapagliflozin therapy may be the result of decreased intraglomerular pressure or reduced tubular cell injury

    Visual ecology of aphids – a critical review on the role of colours in host finding

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    We review the rich literature on behavioural responses of aphids (Hemiptera: Aphididae) to stimuli of different colours. Only in one species there are adequate physiological data on spectral sensitivity to explain behaviour crisply in mechanistic terms. Because of the great interest in aphid responses to coloured targets from an evolutionary, ecological and applied perspective, there is a substantial need to expand these studies to more species of aphids, and to quantify spectral properties of stimuli rigorously. We show that aphid responses to colours, at least for some species, are likely based on a specific colour opponency mechanism, with positive input from the green domain of the spectrum and negative input from the blue and/or UV region. We further demonstrate that the usual yellow preference of aphids encountered in field experiments is not a true colour preference but involves additional brightness effects. We discuss the implications for agriculture and sensory ecology, with special respect to the recent debate on autumn leaf colouration. We illustrate that recent evolutionary theories concerning aphid–tree interactions imply far-reaching assumptions on aphid responses to colours that are not likely to hold. Finally we also discuss the implications for developing and optimising strategies of aphid control and monitoring

    A Primer on the Acute Management of Intravenous Extravasation Injuries for the Plastic Surgeon

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    Intravenous therapy is a common practice among many specialties. Intravenous therapy extravasation is a potential complication to such therapy. Hospitals without a dedicated wound care team trained in these interventions will often default to plastic surgical consultation, making an understanding of available interventions essential to the initial evaluation and management of these injuries. The goal of this article was to provide plastic surgeons and health care providers with a general overview of the acute management of intravenous infiltration and extravasation injuries. Though the decision for surgical versus nonsurgical management is often a clear one for plastic surgeons, local interventions, and therapies are often indicated and under-utilized in the immediate postinfiltration period. Thorough knowledge of these interventions should be a basic requirement in the armamentarium of plastic surgery consultants
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