6,360 research outputs found

    Discovery of a 6.4 h black hole binary in NGC 4490

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    We report on the discovery with Chandra of a strong modulation (~90% pulsed fraction) at ~6.4 h from the source CXOU J123030.3+413853 in the star-forming, low-metallicity spiral galaxy NGC 4490, which is interacting with the irregular companion NGC 4485. This modulation, confirmed also by XMM-Newton observations, is interpreted as the orbital period of a binary system. The spectra from the Chandra and XMM-Newton observations can be described by a power-law model with photon index ~1.5. During these observations, which span from 2000 November to 2008 May, the source showed a long-term luminosity variability by a factor of ~5, between ~2E+38 and 1.1E+39 erg/s (for a distance of 8 Mpc). The maximum X-ray luminosity, exceeding by far the Eddington limit of a neutron star, indicates that the accretor is a black hole. Given the high X-ray luminosity, the short orbital period and the morphology of the orbital light curve, we favour an interpretation of CXOU J123030.3+413853 as a rare high-mass X-ray binary system with a Wolf-Rayet star as a donor, similar to Cyg X-3. This would be the fourth system of this kind known in the local Universe. CXOU J123030.3+413853 can also be considered as a transitional object between high mass X-ray binaries and ultraluminous X-ray sources (ULXs), the study of which may reveal how the properties of persistent black-hole binaries evolve entering the ULX regime.Comment: Fig. 1 in reduced quality; minor changes to match the MNRAS versio

    Effects of submerged vegetation on water clarity across climates

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    A positive feedback between submerged vegetation and water clarity forms the backbone of the alternative state theory in shallow lakes. The water clearing effect of aquatic vegetation may be caused by different physical, chemical, and biological mechanisms and has been studied mainly in temperate lakes. Recent work suggests differences in biotic interactions between (sub)tropical and cooler lakes might result in a less pronounced clearing effect in the (sub)tropics. To assess whether the effect of submerged vegetation changes with climate, we sampled 83 lakes over a gradient ranging from the tundra to the tropics in South America. Judged from a comparison of water clarity inside and outside vegetation beds, the vegetation appeared to have a similar positive effect on the water clarity across all climatic regions studied. However, the local clearing effect of vegetation decreased steeply with the contribution of humic substances to the underwater light attenuation. Looking at turbidity on a whole-lake scale, results were more difficult to interpret. Although lakes with abundant vegetation (>30%) were generally clear, sparsely vegetated lakes differed widely in clarity. Overall, the effect of vegetation on water clarity in our lakes appears to be smaller than that found in various Northern hemisphere studies. This might be explained by differences in fish communities and their relation to vegetation. For instance, unlike in Northern hemisphere studies, we find no clear relation between vegetation coverage and fish abundance or their diet preference. High densities of omnivorous fish and coinciding low grazing pressures on phytoplankton in the (sub)tropics may, furthermore, weaken the effect of vegetation on water clarity

    HVSR and MASW seismic survey for characterizing the local seismic response: A case study in Catania area (Italy)

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    Many recent researches show that the site seismic response is strongly influenced by stratigraphic and topographic features. Site response can reduce or amplify the earthquake induced ground motion. An integrated approach based on passive (HVSR) and active (MASW) seismic surveys, was carried out at the Garibaldi Hospital, located in Catania downtown, in order to evaluate the seismic site response. Fourteen environmental noise records, located near some previously mechanical drillings, were carried out and processed by using the Horizontal to Vertical Spectral Ratio (HVSR) technique. Successively, two MASW prospections were performed at the northern and the southern sides of the Hospital building, following the information deduced from the stratigraphic characteristics of soil drillings. The data obtained from this coupled analysis, method and the information derived by mechanical drillings previously performed, allowed us to obtain the site transfer function which can be related to the H/V average spectrum. Such integrated approach, based on passive and active seismic prospections, showed to be a reliable and quick method to obtain information for a site seismic characterization. According to Italian code a Vs30 profile was achieved and the soil type category was determined

    Strategies and Controversies in the Treatment With Carbon Dioxide Laser of Laryngeal Hemangioma: A Case Series and Review of the Literature

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    Introduction: The hemangioma is the most common vascular tumor, involving the head and neck in 60% of cases. It is rare in the larynx. In children, hemangiomas are more frequent on the subglottis, whereas in adults the most common site is the supraglottis. Laryngeal hemangioma with cavernous features isolated to the free edge of the vocal fold is a very rare clinical finding. We present 2 cases of glottic hemangioma. Both patients reported severe hoarseness. Cases: In the first patient, an extensive blue-purple mass was seen on the right vocal cord. The patient was posted for microlaryngeal surgery with carbon dioxide (CO2) laser. Second patient had a large, smooth, flesh-colored polypoid mass emanating from the left vocal cord. The patient was posted for microlaryngeal surgery. After 2 months, both patients showed a considerable voice improvement. Discussion: Vocal cord hemangiomas are very rare, and they usually cause problem in the voice of the patient. A vascular lesion that may mimic a hemangioma may sometimes result from an organizing hematoma following a hemorrhage on the vocal cords due to voice abuse. Laryngeal hemangiomas also need to be distinguished pathologically from polypoidal vascular granulation tissue that may be produced by laryngeal biopsy, intubation, or trauma. Indirect endoscopy is enough to diagnosis. No active treatment is advised for adult laryngeal hemangiomas unless the lesions are symptomatic or show a tendency to involve other parts. There is no uniformly accepted treatment of head and neck hemangiomas. Surgical excision with laser CO2 microlaryngoscopic techniques gives satisfactory results

    Role of Îą-Tocopherol Acetate on Nasal Respiratory Functions: Mucociliary Clearance and Rhinomanometric Evaluations in Primary Atrophic Rhinitis

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    Primary atrophic rhinitis is a disease of the nose and of paranasalsinuses characterized by a progressive loss of function of nasal and paranasal mucosa caused by a gradual destruction of ciliary mucosalepithelium with atrophy of serous–mucous glands and loss of bonestructures.The aim of this study was to evaluate the therapeutic effects of topic α-tochopherol acetate (vitamin E) in patients with primary atrophicrhinitis based on subjective and objective data.We analyzed 44 patients with dry nose sensation and endoscopic evidence of atrophic nasal mucosa. We analyzed endoscopic mucosascore, anterior rhinomanometry, and nasal mucociliary clearance before and after 6 months of topic treatment with α-tochopherol acetate. For statistical analysis, we used paired samples t test (95% confidence interval [CI], P <.05) for rhinomanometric and muciliary transit time evaluations and analysis of variance 1-way test (95% CI, P <.05) for endoscopic evaluation. All patients showed an improvement in “dry nose” sensation and inperception of nasal airflow. Rhinomanometric examination showed increase of nasal airflow at follow-up (P <.05); nasal mucociliaryclearance showed a reduction in mean transit time (P <.05); and endoscopic evaluation showed significative improvement of hydration of nasalmucosa and significative decreasing nasal crusts and mucusaccumulation (P <.05). Medical treatment for primary atrophic rhinitis is not clearly documented in the literature; in this research, it was demonstrated that α-ochopherol acetate could be a possible treatment for atrophic rhinitis

    Supracricoid Partial Laryngectomy: Oncological and Functional Outcomes

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    Introduction In the present study, we have reviewed the outcomes of patients with supracricoid partial laryngectomy (SCPL) in our institution. Our results show that SCPL is a well-tolerated procedure with generally good functional outcomes for patients with advanced laryngeal cancer. Objective We analyzed the oncological and functional results of a cohort of 35 patients who had undergone SCPL, and we highlighted the complications, identified the overall and disease-free survivals, demonstrating that the reconstructive laryngectomy guarantees the oncological safety and reproducibility of the oncological results, preserving the laryngeal functions and promoting an improvement in the patient's quality of life, favoring communication and interpersonal relationships. Methods Between 2010 and 2018, 35 patients underwent SCPL for primary and recurrent laryngeal squamous cell carcinomas, and they were divided into two subgroups: in 16 cases, the cricohyoidoepiglottopexy according to the Mayer-Piquet technique was performed, while the remaining 19 cases were submitted to the cricohyoidopexy according to the Labayle technique. In addition to evaluating the oncological results of patients undergoing reconstructive laryngectomy, the present study also aimed to evaluate the functionality of the residual larynx and the quality of life. Results The overall and disease-free survivals were of 83% and 76.3% respectively. All patients were able to swallow. The nasogastric tube was removed after a mean period of 21.8 days (range: 14 to 28 days). The mean decannulation time was of 23.4 days after surgery (range: 15 to 36 days). Conclusion The curves for the overall and disease-free survivals show that SCPL can guarantee oncological safety comparable to that of total laryngectomies in diseases in the intermediate stage and in carefully-selected advanced stages

    Small-Cell Carcinoma of Nasopharynx: A Case Report of Unusual Localization

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    Neuroendocrine tumors are a spectrum of rare and highly heterogeneous neoplasms with distinct functional and biological behavior in relation to location, tumor size, and histological differentiation. Neuroendocrine tumors arise from the neuroendocrine cells of the diffuse neuroendocrine system located in almost every organ. Neuroendocrine tumors in the head and neck district are usually reported in sinonasal cavities and larynx. We present the case of a nasopharyngeal small-cell neuroendocrine carcinoma, which, as far as we know, is the 16th case reported in literature

    ClaiMaker: weaving a semantic web of research papers

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    The usability of research papers on the Web would be enhanced by a system that explicitly modelled the rhetorical relations between claims in related papers. We describe ClaiMaker, a system for modelling readers’ interpretations of the core content of papers. ClaiMaker provides tools to build a Semantic Web representation of the claims in research papers using an ontology of relations. We demonstrate how the system can be used to make inter-document queries
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