2,282 research outputs found
A millisecond pulsar in a stellar triple system
Gravitationally bound three-body systems have been studied for hundreds of
years and are common in our Galaxy. They show complex orbital interactions,
which can constrain the compositions, masses, and interior structures of the
bodies and test theories of gravity, if sufficiently precise measurements are
available. A triple system containing a radio pulsar could provide such
measurements, but the only previously known such system, B1620-26 (with a
millisecond pulsar, a white dwarf, and a planetary-mass object in an orbit of
several decades), shows only weak interactions. Here we report precision timing
and multi-wavelength observations of PSR J0337+1715, a millisecond pulsar in a
hierarchical triple system with two other stars. Strong gravitational
interactions are apparent and provide the masses of the pulsar (1.4378(13)
Msun, where Msun is the solar mass and the parentheses contain the uncertainty
in the final decimal places) and the two white dwarf companions (0.19751(15)
Msun and 0.4101(3) Msun), as well as the inclinations of the orbits (both
approximately 39.2 degrees). The unexpectedly coplanar and nearly circular
orbits indicate a complex and exotic evolutionary past that differs from those
of known stellar systems. The gravitational field of the outer white dwarf
strongly accelerates the inner binary containing the neutron star, and the
system will thus provide an ideal laboratory in which to test the strong
equivalence principle of general relativity.Comment: 17 pages, 3 figures, 1 table. Published online by Nature on 5 Jan
2014. Extremely minor differences with published version may exis
Strengthening the relationship:A digital and educational exchange between Portuguese and Dutch mental health care associations
BackgroundEuropean differences in Mental Healthcare systems (MHS) and European challenges within MHS, like migration, climate change and lack of qualified professionals, require collaboration between stakeholders from individual countries within the European Union.Purpose: To exchange information between national and international associations and inspire Dutch clinical psychologists in training.MethodA digital event was organized and three renowned associations from both Portugal and The Netherlands presented their organization and current developments. This input was used in a discussion round where participants from both countries participated. ConclusionThis event provided positive outcomes on multiple levels, including being educational for specialists in training, building and maintaining the relationship between the professionals and association of both countries and providing new and inspiring perspectives that can help mutual MHS. The differences show the work that lies ahead, to create more European uniformity within MHS and to further benefit from international collaboration.<br/
A 450 million years long latitudinal gradient in age-dependent extinction.
Leigh Van Valen famously stated that under constant conditions extinction probability is independent of species age. To test this 'law of constant extinction', we developed a new method using deep learning to infer age-dependent extinction and analysed 450Â myr of marine life across 21 invertebrate clades. We show that extinction rate significantly decreases with age in >Â 90% of the cases, indicating that most species died out soon after their appearance while those which survived experienced ever decreasing extinction risk. This age-dependent extinction pattern is stronger towards the Equator and holds true when the potential effects of mass extinctions and taxonomic inflation are accounted for. These results suggest that the effect of biological interactions on age-dependent extinction rate is more intense towards the tropics. We propose that the latitudinal diversity gradient and selection at the species level account for this exceptional, yet little recognised, macroevolutionary and macroecological pattern
A 450 million years long latitudinal gradient in age-dependent extinction
Leigh Van Valen famously stated that under constant conditions extinction probability is independent of species age. To test this 'law of constant extinction', we developed a new method using deep learning to infer age-dependent extinction and analysed 450 myr of marine life across 21 invertebrate clades. We show that extinction rate significantly decreases with age in > 90% of the cases, indicating that most species died out soon after their appearance while those which survived experienced ever decreasing extinction risk. This age-dependent extinction pattern is stronger towards the Equator and holds true when the potential effects of mass extinctions and taxonomic inflation are accounted for. These results suggest that the effect of biological interactions on age-dependent extinction rate is more intense towards the tropics. We propose that the latitudinal diversity gradient and selection at the species level account for this exceptional, yet little recognised, macroevolutionary and macroecological pattern
Primary cutaneous aggressive epidermotropic cytotoxic T-cell lymphomas: reappraisal of a provisional entity in the 2016 WHO classification of cutaneous lymphomas.
Primary cutaneous CD8-positive aggressive epidermotropic T-cell lymphoma is a rare and poorly characterized variant of cutaneous lymphoma still considered a provisional entity in the latest 2016 World Health Organization Classification of Cutaneous lymphomas. We sought to better characterize and provide diagnostic and therapeutic guidance of this rare cutaneous lymphoma. Thirty-four patients with a median age of 77 years (range 19-89 years) presented primarily with extensive annular necrotic plaques or tumor lesions with frequent mucous membrane involvement. The 5-year survival was 32% with a median survival of 12 months. A subset of 17 patients had a prodrome of chronic patches prior to the development of aggressive ulcerative lesions. We identified cases with lack of CD8 or αβ T-cell receptor expression yet with similar clinical and pathological presentation. Allogeneic stem cell transplantation provided partial or complete remissions in 5/6 patients. We recommend the term primary cutaneous aggressive epidermotropic cytotoxic T-cell lymphoma as this more broad designation better describes this clinical-pathologic presentation, which allows the inclusion of cases with CD8 negative and/or αβ/γδ T-cell receptor chain double-positive or double-negative expression. We have identified early skin signs of chronic patch/plaque lesions that are often misdiagnosed as eczema, psoriasis, or mycosis fungoides. Our experience confirms the poor prognosis of this entity and highlights the inefficacy of our standard therapies with the exception of allogeneic stem cell transplantation in selected cases
Stratigraphic context and paleoenvironmental significance of minor taxa (Pisces, Reptilia, Aves, Rodentia) from the late Early Pleistocene palaeoanthropological site of Buia (Eritrea)
none13noneL. Rook; M. Ghinassi; G. Carnevale; M. Delfino; M. Pavia; L. Bondioli ; F. Candilio; A. Coppa; B. MartĂnez-Navarro; T. Medin; M. Papini; C. Zanolli; Y. LibsekalL., Rook; Ghinassi, Massimiliano; G., Carnevale; M., Delfino; M., Pavia; L., Bondioli; F., Candilio; A., Coppa; B., MartĂnez Navarro; T., Medin; M., Papini; C., Zanolli; Y., Libseka
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