6,598 research outputs found
Hydrohalite Salt-albedo Feedback Could Cool M-dwarf Planets
A possible surface type that may form in the environments of M-dwarf planets
is sodium chloride dihydrate, or "hydrohalite" (NaCl 2HO), 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 CO
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
CO 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
Association of Disease Location and Treatment With Survival in Diffuse Large B-Cell Lymphoma of the Eye and Ocular Adnexal Region.
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
Quantum key distribution over 122 km of standard telecom fiber
We report the first demonstration of quantum key distribution over a standard
telecom fiber exceeding 100 km in length. Through careful optimisation of the
interferometer and single photon detector, we achieve a quantum bit error ratio
of 8.9% for a 122km link, allowing a secure shared key to be formed after error
correction and privacy amplification. Key formation rates of up to 1.9 kbit/sec
are achieved depending upon fiber length. We discuss the factors limiting the
maximum fiber length in quantum cryptography
Double-Peaked Narrow-Line Active Galactic Nuclei. II. The Case Of Equal Peaks
Active galactic nuclei (AGNs) with double-peaked narrow lines (DPAGNs) may be caused by kiloparsec-scale binary AGNs, bipolar outflows, or rotating gaseous disks. We examine the class of DPAGNs in which the two narrow-line components have closely similar intensity as being especially likely to involve disks or jets. Two spectroscopic indicators support this likelihood. For DPAGNs from Smith et al., the "equal-peaked" objects (EPAGNs) have [Ne V]/[O III] ratios lower than for a control sample of non-double-peaked AGNs. This is unexpected for a pair of normal AGNs in a galactic merger, but may be consistent with [O III] emission from a rotating ring with relatively little gas at small radii. Also, [O III]/H beta ratios of the redshifted and blueshifted systems in the EPAGN are more similar to each other than in a control sample, suggestive of a single ionizing source and inconsistent with the binary interpretation.University Cooperative Society of the University of Texas at AustinJane and Roland Blumberg Cenntenial Professorship in AstronomyAlfred P. Sloan FoundationNational Aeronautics and Space AdministrationNational Science FoundationU.S. Department of EnergyJapanese MonbukagakushoMax Planck SocietyUniversity of ChicagoInstitute for Advanced StudyJapan Participation GroupJohns Hopkins UniversityKorean Scientist GroupLos Alamos National LaboratoryMax-Planck-Institute for Astronomy (MPIA)Max-Planck-Institute for Astrophysics (MPA)New Mexico State UniversityUniversity of PittsburghUniversity of PortsmouthPrinceton UniversityUnited States Naval ObservatoryUniversity of WashingtonFermilabAstronom
Reducing Stigma toward the Transgender Community: An Evaluation of a Humanizing and Perspective-Taking Intervention
Transgender (TG) individuals are an understudied group at high risk of experiencing discrimination and associated adverse mental health outcomes (IOM, 2011). Although many studies demonstrate that contact reduces negative attitudes toward out-groups, few studies have examined the link between contact and attitudes toward the TG community (Hill & Willoughby, 2005; Walchet al., 2012). This study represents one of the first attempts to understand how to effectively reduce stigma toward the TG community. Results indicate that education alone is not enough to change attitudes; in fact, there is some evidence that associating transgenderism with psychopathology may heighten stigma. Consistent with prior research on stigma towards the mentally ill, the current study suggests that both exposure to intimate media depictions of the “other” (Reinke et al., 2004) and perspective-taking (Mann & Himelein, 2008) could strengthen educational campaigns designed to combat stigma
Avoiding the Detector Blinding Attack on Quantum Cryptography
We show the detector blinding attack by Lydersen et al [1] will be
ineffective on most single photon avalanche photodiodes (APDs) and certainly
ineffective on any detectors that are operated correctly. The attack is only
successful if a redundant resistor is included in series with the APD, or if
the detector discrimination levels are set inappropriately
Postenucleation adjuvant chemotherapy with vincristine, etoposide, and carboplatin for the treatment of high-risk retinoblastoma.
BACKGROUND: Analysis of 52 eyes with high-risk retinoblastoma managed with postenucleation adjuvant chemotherapy using vincristine sulfate, etoposide phosphate, and carboplatin showed no evidence of systemic metastasis in any case during a mean (range) follow-up of 66 (12-202) months.
PURPOSE: To determine the efficacy of postenucleation adjuvant chemotherapy with vincristine, etoposide, and carboplatin in the prevention of metastasis for patients with high-risk retinoblastoma.
METHODS: Retrospective, nonrandomized, interventional case series of 52 eyes in 51 patients with high-risk retinoblastoma consisting of tumor invasion into the anterior segment, posterior uvea 3 mm or greater, postlaminar optic nerve, or any combination of posterior uvea and optic nerve involvement.
RESULTS: Of 51 consecutive patients with high-risk retinoblastoma, there were 30 males (59%) and 21 females (41%), with a median age of 28 months at diagnosis. All 52 eyes were classified as group E. The main histopathologic risk factors included anterior segment invasion (7 [13%]), isolated massive posterior uveal invasion of 3 mm or greater (6 [12%]), isolated postlaminar optic nerve invasion (15 [29%]), or any posterior uveal invasion with any optic nerve involvement (24 [46%]). There was additional invasion into the sclera (3 [6%]) and extrascleral structures, including the orbit (1 [2%]). A single histopathologic high-risk factor was present in 32 eyes (62%), whereas 20 eyes (38%) manifested 2 or more high-risk characteristics. Based on previously published series, untreated high-risk retinoblastoma carries at least a 24% risk for metastatic disease. In the present series, using vincristine, etoposide, and carboplatin in all cases, there was no metastasis during a mean follow-up of 66 months (median [range], 55 [12-202] months).
CONCLUSIONS: Retinoblastoma with invasion into the postlaminar optic nerve and/or posterior uvea is at high risk for metastasis and death. In this study, postenucleation chemotherapy using vincristine, etoposide, and carboplatin was effective in preventing metastasis in every case (100%)
Emission-Line Properties of the Optical Filaments of NGC 1275
Extended nebular filaments are seen at optical wavelengths in NGC 1275, the
central galaxy in the Perseus cluster. The agents responsible for the
excitation of these filaments remain poorly understood. In this paper we
investigate possible mechanisms for powering the filaments, using measurements
from an extensive spectroscopic data set acquired at the Lick Observatory 3-m
Shane telescope. The results show that the filaments are in an extremely low
ionization and excitation state. The high signal-to-noise ratio of the spectra
allows us to measure or place sensitive upper limits on weak but important
diagnostic lines. We compare the observed line intensity ratios to the
predictions of various ionization models, including photoionization by an
active galactic nucleus, shock heating, stellar photoionization, and
photoionization by the intracluster medium. We also investigate possible roles
for cluster extreme-ultraviolet emission, and filtering of cluster soft X-ray
emission by an ionized screen, in the energetics of the filaments. None of
these mechanisms provides an entirely satisfactory explanation for the physical
state of the nebulae. Heating and ionization by reconnection of the
intracluster magnetic field remains a potentially viable alternative, which
merits further investigation through Faraday rotation studies.Comment: Accepted for publication in Ap
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