964 research outputs found

    A generalized no-broadcasting theorem

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    We prove a generalized version of the no-broadcasting theorem, applicable to essentially \emph{any} nonclassical finite-dimensional probabilistic model satisfying a no-signaling criterion, including ones with ``super-quantum'' correlations. A strengthened version of the quantum no-broadcasting theorem follows, and its proof is significantly simpler than existing proofs of the no-broadcasting theorem.Comment: 4 page

    Phylogenetic revision of Backhousieae (Myrtaceae): Neogene divergence, a revised circumscription of Backhousia and two new species

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    Backhousieae is a small tribe of Myrtaceae composed of two genera (Backhousia and Choricarpia) endemic to Australia. Phylogenetic analyses (parsimony, maximum likelihood and Bayesian) were performed on a combined chloroplast (matK, trnH–psbA, trnC–psbM, trnL–F, rps16) and nuclear (internal transcribed spacers) dataset for all nine species of Backhousia, two species of Choricarpia and two undescribed species. Backhousieae is monophyletic; however, Choricarpia is embedded within Backhousia. In all analyses there were four strongly supported clades containing two to four taxa, with no support for relationships among clades, and the relationships of B. bancroftii and B. citriodora remain unresolved. Bayesian relaxed-clock molecular dating indicated that the Backhousieae has been potentially present in rainforest across Australia for more than 50 million years. The current distribution of Backhousia is inferred to be largely due to the contraction of Australian rainforest in the Neogene. New combinations in Backhousia are made for the two species of Choricarpia, and B. gundarara and B. tetraptera are described as new species. B. gundarara is known only from the Kimberley region of Western Australia, widely disjunct from the remaining Backhousia in eastern Queensland and New South Wales, and appears to be a lineage isolated by increasing aridity during the Miocene

    Circular orbits and spin in black-hole initial data

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    The construction of initial data for black-hole binaries usually involves the choice of free parameters that define the spins of the black holes and essentially the eccentricity of the orbit. Such parameters must be chosen carefully to yield initial data with the desired physical properties. In this paper, we examine these choices in detail for the quasiequilibrium method coupled to apparent-horizon/quasiequilibrium boundary conditions. First, we compare two independent criteria for choosing the orbital frequency, the "Komar-mass condition" and the "effective-potential method," and find excellent agreement. Second, we implement quasi-local measures of the spin of the individual holes, calibrate these with corotating binaries, and revisit the construction of non-spinning black hole binaries. Higher-order effects, beyond those considered in earlier work, turn out to be important. Without those, supposedly non-spinning black holes have appreciable quasi-local spin; furthermore, the Komar-mass condition and effective potential method agree only when these higher-order effects are taken into account. We compute a new sequence of quasi-circular orbits for non-spinning black-hole binaries, and determine the innermost stable circular orbit of this sequence.Comment: 24 pages, 17 figures, accepted for publication in Physical Review D, revtex4; Fixed error in computing proper separation and updated figures and tables accordingly, added reference to Sec. IV.A, fixed minor error in Sec. IV.B, added new data to Tables IV and V, fixed 1 reference, fixed error in Eq. (A7b), included minor changes from PRD editin

    A temperate palaeodiversity peak in Mesozoic dinosaurs and evidence for Late Cretaceous geographical partitioning

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    Aim  Modern biodiversity peaks in the tropics and declines poleward, a pattern that is potentially driven by climate. Although this latitudinal biodiversity gradient (LBG) also characterizes the marine invertebrate fossil record, distributions of ancient terrestrial faunas are poorly understood. This study utilizes data on the dinosaur fossil record to examine spatial patterns in terrestrial biodiversity throughout the Mesozoic.\ud Location  We compiled data on fossil occurrences across the globe.\ud Methods  We compiled a comprehensive dataset of Mesozoic dinosaur genera (738), including birds. Following the utilization of sampling standardization techniques to mediate for the uneven sampling of the fossil record, we constructed latitudinal patterns of biodiversity from this dataset.\ud Results  The dominant group of Mesozoic terrestrial vertebrates did not conform to the modern LBG. Instead, dinosaur diversity was highest at temperate palaeolatitudes throughout the 160 million year span of dinosaurian evolutionary history. Latitudinal diversity correlates strongly with the distribution of land area. Late Cretaceous sauropods and ornithischians exhibit disparate LBGs.\ud Main conclusions  The continuity of the palaeotemperate peak in dinosaur diversity indicates a diminished role for climate on the Mesozoic LBG; instead, dinosaur diversity may have been driven by the amount of land area among latitudinal belts. There is no evidence that the tropics acted as a cradle for dinosaur diversity. Geographical partitioning among major clades of herbivorous dinosaurs in the Late Cretaceous may result from the advanced stages of continental fragmentation and/or differing responses to increasing latitudinal climatic zonation. Our results suggest that the modern-day LBG on land was only established 30 million years ago, following a significant post-Eocene recalibration, potentially related to increased seasonality

    Six new species of Utricularia (Lentibulariaceae) from Northern Australia

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    Six new species of Utricularia (Lentibulariaceae) are recognised from northern Australia. Descriptions of the new species Utricularia albertiana R.W.Jobson & Baleeiro, U. bidentata R.W.Jobson & Baleeiro, U. hamata R.W.Jobson & M.D.Barrett, U. magna R.W.Jobson & M.D.Barrett, U. papilliscapa R.W.Jobson & M.D.Barrett, and U. limmenensis R.W.Jobson (Lentibulariaceae) are provided. Diagnostic features for all six species are illustrated, and distribution, habitat, and conservation status are discussed

    Risk factors for dislocation after primary total hip replacement:a systematic review and meta-analysis of 125 studies involving approximately five million hip replacements

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    Background:&nbsp;Dislocation following total hip replacement is associated with repeated admissions to hospital and substantial costs to the health system. Factors influencing dislocation following primary total hip replacement are not well understood. We aimed to assess the association of various factors with dislocation risk following primary total hip replacement. Methods:&nbsp;We did a systematic review and meta-analysis of longitudinal studies reporting associations of patient-related, surgery-related, implant-related, and hospital-related factors with dislocation risk after primary total hip replacement. We searched MEDLINE, Embase, Web of Science, and the Cochrane Library for all relevant articles published up to March 8, 2019. Summary measures of association were calculated with relative risks (RRs) and 95% CIs. This study is registered on PROSPERO, number CRD42019121378. Findings:&nbsp;We identified 149 articles based on 125 unique studies with data on 4 633 935 primary total hip replacements and 35 264 dislocations. The incidence of dislocation ranged from 0&middot;12% to 16&middot;13%, with an overall pooled incidence of 2&middot;10% (95% CI 1&middot;83&ndash;2&middot;38) over a weighted mean follow-up duration of 6 years. Based on the median year of data collection, a significant decline in dislocation rates was observed from 1971 to 2015. The risk of dislocation did not differ significantly between male versus female patients (RR 0&middot;97; 95% CI 0&middot;88&ndash;1&middot;08), was higher in those aged 70 years and older than in those younger than 70 years (1&middot;27; 1&middot;02&ndash;1&middot;57), and was lower in those from high versus low income groups (0&middot;79; 0&middot;74&ndash;0&middot;85). White ethnicity (only when compared with Asian ethnicity), drug use disorder, and social deprivation were significantly associated with increased dislocation risk. The risk of dislocation was higher in patients with body-mass index (BMI) of 30 kg/m2&nbsp;or higher than in those with BMI lower than 30 kg/m2&nbsp;(RR 1&middot;38; 95% CI 1&middot;03&ndash;1&middot;85). Medical factors and those related to surgical history that were significantly associated with increased dislocation risk included neurological disorder, psychiatric disease, comorbidity indices, previous surgery including spinal fusion, and surgical indications including avascular necrosis, rheumatoid arthritis, inflammatory arthritis, and osteonecrosis. Surgical factors such as the anterolateral, direct anterior, or lateral approach, and posterior approach with short external rotator and capsule repair were significantly associated with reduced dislocation risk. At the implant level, larger femoral head diameters, elevated acetabular liners, dual mobility cups, cemented fixations, and standard femoral neck lengths significantly reduced the risk of dislocation. Hospital-related factors such as experienced surgeons and high surgeon procedure volume significantly reduced the risk of dislocation. Interpretation:&nbsp;Dislocation following primary total hip replacement has declined over time. Surgical approaches that reduce dislocation risk can be used by clinicians during primary total hip replacement, and alternative bearings such as dual mobility can be used in individuals at high risk of dislocation. Modifiable risk factors such as high BMI and comorbidities might also be amenable to optimisation before surgery. </div
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