88 research outputs found

    Collisional dissipation of Alfvén waves in a partially ionised solar chromosphere

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    Certain regions of the solar atmosphere are at sufficiently low temperatures to be only partially ionised. The lower chromosphere contains neutral atoms, the existence of which greatly increases the efficiency of the damping of waves due to collisional friction momentum transfer. More specifically the Cowling conductivity can be up to 12 orders of magnitude smaller than the Spitzer value, so that the main damping mechanism in this region is due to the collisions between neutrals and positive ions (Khodachenko et al. 2004, A&A, 422, 1073). Using values for the gas density and temperature as functions of height taken from the VAL C model of the quiet Sun (Vernazza et al. 1981, ApJS, 45, 635), an estimate is made for the dependance of the Cowling conductivity on height and strength of magnetic field. Using both analytic and numerical approaches the passage of Alfvén waves over a wide spectrum through this partially ionised region is investigated. Estimates of the efficiency of this region in the damping of Alfvén waves are made and compared for both approaches. We find that Alfvén waves with frequencies above 0.6 Hz are completely damped and frequencies below 0.01 Hz unaffected

    Pengaruh Pembelajaran Problem Based Learning (PBL) Terhadap Kemampuan Representasi Matematis Siswa Di Kelas VIII Yayasan Perguruan Islam SMP Cerdasmurni Tembung

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    Compositions and methods for inhibiting and/or sensitizing or re-sensitizing a parasite to an antiparasitic drug are provided. The compositions can comprise a rifamycin derivative or a pharmaceutically acceptable salt, hydrate, or prodrug thereof in an amount and formulation sufficient to inhibit or induce drug-sensitization in a parasite. The methods can comprise administering a rifamycin derivative or a pharmaceutically acceptable salt, hydrate, or prodrug thereof to a parasite in an amount and formulation sufficient to inhibit or induce drug-sensitization in the parasite.U

    European aerosol phenomenology - 8 : Harmonised source apportionment of organic aerosol using 22 Year-long ACSM/AMS datasets

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    Organic aerosol (OA) is a key component of total submicron particulate matter (PM1), and comprehensive knowledge of OA sources across Europe is crucial to mitigate PM1 levels. Europe has a well-established air quality research infrastructure from which yearlong datasets using 21 aerosol chemical speciation monitors (ACSMs) and 1 aerosol mass spectrometer (AMS) were gathered during 2013-2019. It includes 9 non-urban and 13 urban sites. This study developed a state-of-the-art source apportionment protocol to analyse long-term OA mass spectrum data by applying the most advanced source apportionment strategies (i.e., rolling PMF, ME-2, and bootstrap). This harmonised protocol was followed strictly for all 22 datasets, making the source apportionment results more comparable. In addition, it enables quantification of the most common OA components such as hydrocarbon-like OA (HOA), biomass burning OA (BBOA), cooking-like OA (COA), more oxidised-oxygenated OA (MO-OOA), and less oxidised-oxygenated OA (LO-OOA). Other components such as coal combustion OA (CCOA), solid fuel OA (SFOA: mainly mixture of coal and peat combustion), cigarette smoke OA (CSOA), sea salt (mostly inorganic but part of the OA mass spectrum), coffee OA, and ship industry OA could also be separated at a few specific sites. Oxygenated OA (OOA) components make up most of the submicron OA mass (average = 71.1%, range from 43.7 to 100%). Solid fuel combustion-related OA components (i.e., BBOA, CCOA, and SFOA) are still considerable with in total 16.0% yearly contribution to the OA, yet mainly during winter months (21.4%). Overall, this comprehensive protocol works effectively across all sites governed by different sources and generates robust and consistent source apportionment results. Our work presents a comprehensive overview of OA sources in Europe with a unique combination of high time resolution (30-240 min) and long-term data coverage (9-36 months), providing essential information to improve/validate air quality, health impact, and climate models.Peer reviewe

    Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

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    Contains fulltext : 172380.pdf (publisher's version ) (Open Access

    Esophageal hiatal hernia in three exotic felines--Lynx lynx, Puma concolore, Panthera leo.

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    Hiatal hernia was diagnosed in three exotic felines-lynx (Lynx lynx), cougar (Puma concolore), and lion (Panthera leo). All cats had a history of anorexia. Thoracic and abdominal radiographs showed evidence of a soft tissue mass within the caudal mediastinum suggestive of a hiatal hernia in all animals. A barium esophagram was performed in one case. All animals underwent thoracic or abdominal surgery for hernia reduction. Surgical procedures included: intercostal thoracotomy with herniorrhaphy and esophagopexy (lynx and cougar), and incisional gastropexy (lion). Concurrent surgical procedures performed were gastrotomy for gastric foreign body removal and jejunostomy tube placement. Clinical signs related to the hiatal hernia disappeared after surgery and recurrence of signs was not reported for the time of follow-up

    Compositions and methods for drug sensitization of parasites

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    Compositions and methods for inhibiting and/or sensitizing or re-sensitizing a parasite to an antiparasitic drug are provided. The compositions can comprise a rifamycin derivative or a pharmaceutically acceptable salt, hydrate, or prodrug thereof in an amount and formulation sufficient to inhibit or induce drug-sensitization in a parasite. The methods can comprise administering a rifamycin derivative or a pharmaceutically acceptable salt, hydrate, or prodrug thereof to a parasite in an amount and formulation sufficient to inhibit or induce drug-sensitization in the parasite.U
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