10,910 research outputs found

    Hydrohalite Salt-albedo Feedback Could Cool M-dwarf Planets

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    A possible surface type that may form in the environments of M-dwarf planets is sodium chloride dihydrate, or "hydrohalite" (NaCl \cdot 2H2_2O), which can precipitate in bare sea ice at low temperatures. Unlike salt-free water ice, hydrohalite is highly reflective in the near-infrared, where M-dwarf stars emit strongly, making the effect of the interaction between hydrohalite and the M-dwarf SED necessary to quantify. We carried out the first exploration of the climatic effect of hydrohalite-induced salt-albedo feedback on extrasolar planets, using a three-dimensional global climate model. Under fixed CO2_2 conditions, rapidly-rotating habitable-zone M-dwarf planets receiving 65% or less of the modern solar constant from their host stars exhibit cooler temperatures when an albedo parameterization for hydrohalite is included in climate simulations, compared to simulations without such a parameterization. Differences in global mean surface temperature with and without this parameterization increase as the instellation is lowered, which may increase CO2_2 build-up requirements for habitable conditions on planets with active carbon cycles. Synchronously-rotating habitable-zone M-dwarf planets appear susceptible to salt-albedo feedback at higher levels of instellation (90% or less of the modern solar constant) than planets with Earth-like rotation periods, due to their cooler minimum day-side temperatures. These instellation levels where hydrohalite seems most relevant correspond to several recently-discovered potentially habitable M-dwarf planets, including Proxima Centauri b, TRAPPIST-1e, and LHS 1140b, making an albedo parameterization for hydrohalite of immediate importance in future climate simulations.Comment: 12 pages, 4 figures, 1 table, accepted for publication in the Astrophysical Journa

    CeMnNi4: an impostor half-metal

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    Recent experiments show CeMnNi4_{4} to have a nearly integer magnetic moment and a relatively large transport spin polarization, as probed by Andreev reflection, suggesting that the material is a half metal or close to it. However, the calculations reported here show that it is not a half metal at all, but rather a semimetal of an unusual nature. Phonon properties should also be quite unusual, with rattling low-frequency Mn modes. Nontrivial transport properties, including a large thermolectric figure of merit, ZT,ZT, are predicted in the ferromagnetic state of the well ordered stoichiometric CeMnNi4_{4}Comment: 4 pages, 6 fig

    Radio loud far-infrared galaxies

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    The first results are presented of a multiwavelength study of Infrared Astronomy Satellite (IRAS) galaxies with excess radio emission. The sample was selected by cross correlating the IRAS Faint Source Survey, and the Point Source Catalogue with the Texas radio survey. Recent optical (imaging and spectroscopic) and radio (VLA) observations are discussed. These observations will be used to investigate possible connections between radio galaxy activity, star formation and galaxy interactions

    Unconditionally secure quantum key distribution over 50km of standard telecom fibre

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    We demonstrate a weak pulse quantum key distribution system using the BB84 protocol which is secure against all individual attacks, including photon number splitting. By carefully controlling the weak pulse intensity we demonstrate the maximum secure bit rate as a function of the fibre length. Unconditionally secure keys can be formed for standard telecom fibres exceeding 50 km in length.Comment: 9 pages 2 figure

    Association of Disease Location and Treatment With Survival in Diffuse Large B-Cell Lymphoma of the Eye and Ocular Adnexal Region.

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    Importance: Primary diffuse large B-cell lymphoma (DLBCL) of the ocular region is rare, and the utility of surgery and radiation therapy remains unresolved. Objective: To explore the clinical characteristics and determine factors associated with overall survival in primary vitreoretinal lymphoma (PVRL) and ocular adnexal (OA)-uveal DLBCL. Design, Setting, and Participants: This retrospective analysis included 396 patients with ophthalmic DLBCL from January 1, 1973, through December 31, 2014, using the Surveillance, Epidemiology, and End Results database. The median follow-up was 39.0 months (interquartile range, 5.1-72.9 months). All patients diagnosed with primary DLBCL of the eye or retina (PVRL) or the eyelid, conjunctiva, choroid, ciliary body, lacrimal gland, or orbit (OA-uveal lymphoma) were included. Patients diagnosed at autopsy or with additional neoplastic disease were excluded. Main Outcomes and Measures: Patient demographic characteristics, disease location, treatment modalities, and overall survival. Results: Forty-seven patients with PVRL (24 women [51.1%] and 23 men [48.9%]) and 349 with OA-uveal DLBCL (192 women [55.0%] and 157 men [45.0%]) had a similar mean (SD) age at diagnosis (69.6 [12.3] vs 66.1 [17.7] years). No difference in the use of surgery or radiation therapy by location was found. For all PVRL and OA-uveal DLBCL, a Cox proportional hazards regression model affirmed that age older than 60 years was associated with increased risk for death (hazard ratio [HR], 2.7; 95% CI, 1.9-4.0; P \u3c .001). Gross total resection was associated with a decreased risk for death (HR, 0.5; 95% CI, 0.3-0.9; P = .04), whereas radiation therapy was not. The 5-year overall survival among patients with PVRL was 41.4% (SE, 8.6%); among those with OA-uveal DLBCL, 59.1% (SE, 2.8%; Mantel-Cox test, P = .007). Median overall survival was lower in PVRL (38.0 months; 95% CI, 14.2-61.8 months) than in OA-uveal DLBCL (96.0 months; 95% CI, 67.3-124.7 months; Mantel-Cox test, P = .007). In addition, median overall survival in ophthalmic-only disease was higher (84.0 months; 95% CI, 63.2-104.8 months) than that in primary DLBCL that occurred outside the central nervous system and ophthalmic regions (46.0 months; 95% CI, 44.4-47.6 months; Mantel-Cox test, P \u3c .001). Conclusions and Relevance: The 5-year survival in PVRL vs OA-uveal DLBCL differed by 17.7%, and overall survival was greater in ophthalmic DLBCL than in DLBCL located outside the central nervous system and ophthalmic regions. Younger age (≤60 years) and gross total resection were associated with increased survival

    COMPARING THE IMPACTS OF RETIREE VERSUS WORKING-AGE FAMILIES ON A SMALL RURAL REGION: AN APPLICATION OF THE WISCONSIN ECONOMIC IMPACT MODELING SYSTEM

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    The Wisconsin Economic Impact Modeling System, a conjoined input-output/econometric model of Wisconsin counties, is used to simulate the economic and fiscal impact of two alternative residential development patterns. Under the first scenario, the impact of migrating retirees on a small tri-county region in northern Wisconsin is examined. Under the second scenario, the impact of the migration of younger families with children is examined. A comparison-contrast between the two scenarios demonstrates that the characteristics of the migrating household can have a significant impact on the nature of the impacts.Community/Rural/Urban Development,

    THE IMPACT OF THE YOUNG-OLD AND THE OLD-OLD ON A SMALL RURAL REGION: AN APPLICATION OF THE WISCONSIN ECONOMIC IMPACT MODELING SYSTEM

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    The literature on the economic and fiscal impacts of in-migrating retirees on rural communities concentrates on the young, newly-retired. An issue not systematically addressed are the impacts on the communities as these retirees age. The Wisconsin Economic Impact Modeling System, a county level conjoined input-output/econometrics simulation model, is used to assess the impact of an aging rural population. Using data from the US Bureau of Labor Statistics' Consumer Expenditure Survey, profiles of two household types are constructed and used to simulate the economic impact of an additional 500 elderly households into a small rural economy. Household types vary by age and, as a result, have different income levels and expenditure patterns. As hypothesized, the magnitude and nature of impacts is in direct proportion to relative household size and income level.aging, economic impacts, development policy, Community/Rural/Urban Development,
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