15,204 research outputs found
Aperture-free star formation rate of SDSS star-forming galaxies
Large area surveys with a high number of galaxies observed have undoubtedly
marked a milestone in the understanding of several properties of galaxies, such
as star-formation history, morphology, and metallicity. However, in many cases,
these surveys provide fluxes from fixed small apertures (e.g. fibre), which
cover a scant fraction of the galaxy, compelling us to use aperture corrections
to study the global properties of galaxies. In this work, we derive the current
total star formation rate (SFR) of Sloan Digital Sky Survey (SDSS) star-forming
galaxies, using an empirically based aperture correction of the measured flux for the first time, thus minimising the uncertainties associated
with reduced apertures. All the fluxes have been
extinction-corrected using the ratio free from aperture
effects. The total SFR for 210,000 SDSS star-forming galaxies has been
derived applying pure empirical and aperture
corrections based on the Calar Alto Legacy Integral Field Area (CALIFA) survey.
We find that, on average, the aperture-corrected SFR is 0.65dex higher
than the SDSS fibre-based SFR. The relation between the SFR and stellar mass
for SDSS star-forming galaxies (SFR--) has been obtained, together
with its dependence on extinction and equivalent width. We
compare our results with those obtained in previous works and examine the
behaviour of the derived SFR in six redshift bins, over the redshift range . The SFR-- sequence derived here is in
agreement with selected observational studies based on integral field
spectroscopy of individual galaxies as well as with the predictions of recent
theoretical models of disc galaxies
Broadly tunable (440-670 nm) solid-state organic laser with disposable capsules
An innovative concept of thin-film organic solid-state laser is proposed,
with diffraction-limited output and a broad tuning range covering the visible
spectrum under UV optical pumping. The laser beam is tunable over 230 nm, from
440 to 670 nm, with a 3 nm full width at half maximum typical spectral width.
The structure consists of a compact fixed bulk optical cavity, a polymeric
intracavity etalon for wavelength tuning, as well as five different disposable
glass slides coated with a dye-doped polymer film, forming a very simple and
low-cost gain medium. The use of interchangeable/disposable "gain capsules" is
an alternative solution to photodegradation issues, since gain chips can be
replaced without realignment of the cavity. The laser lifetime of a single chip
in ambient conditions and without encapsulation was extrapolated to be around
107 pulses at a microjoule energy-per-pulse level
A calcareous nannofossil and organic geochemical study of marine palaeoenvironmental changes across the Sinemurian/Pliensbachian (early Jurassic, ~191Ma) in Portugal
The Sinemurian/Pliensbachian boundary (~ 191 Ma) is acknowledged as one of the most important steps in the radiation of planktonic organisms, especially primary producers such as dinoflagellates and coccolithophores. To date, there is no detailed study documenting changes in planktonic assemblages related to palaeoceanographic changes across this boundary. The aim of this study is to characterize the palaeoenvironmental changes occurring across the Sinemurian/Pliensbachian boundary at the São Pedro de Moel section (Lusitanian Basin, Portugal) using micropalaeontology and organic geochemistry approaches. Combined calcareous nannofossil assemblage and lipid biomarker data document for a decrease in primary productivity in relation to a major sea-level rise occurring above the boundary. The Lusitanian Basin was particularly restricted during the late Sinemurian with a relatively low sea level, a configuration that led to the recurrent development of black shales. After a sharp sea-level fall, the basin became progressively deeper and more open during the earliest Pliensbachian, subsequently to a major transgression. This sea-level increase seems to have been a global feature and could have been related to the opening of the Hispanic Corridor that connected the Tethys and palaeo-Pacific oceans. The palaeoceanographic and palaeoclimatic changes induced by this opening may have played a role in the diversification of coccolithophores with the first occurrence or colonization of Tethyan waters by placolith-type coccoliths
Constraining Elko Dark Matter at the LHC with Monophoton Events
A mass dimension one fermion, also known as Elko, constitutes a dark matter
candidate which might interact with photons at the tree level in a specific
fashion. In this work, we investigate the constraints imposed by unitarity and
LHC data on this type of interactions using the search for new physics in
monophoton events. We found that Elkos which can explain the dark matter relic
abundance mainly through electromagnetic interactions are excluded at the
95\%CL by the 8 TeV LHC data for masses up to 1 TeV.Comment: 6 pages, 4 figure
Sarcoidosis and Multiple Myeloma: A Case Report and Literature Review
The existence of a sarcoidosis-lymphoma syndrome has been previously proposed since the relation between sarcoidosis and an increased risk of lymphoproliferative disorders is well established. Multiple myeloma is a malignant multifocal proliferation of clonal plasma cells within the bone marrow, and its association with sarcoidosis has been rarely described. We present a concurrent diagnosis of sarcoidosis and multiple myeloma and make a brief analysis of the reported cases in the literature. A 65-year-old woman underwent surgery for the excision of a wrist mass that presented 3 years before. Histological analysis showed sarcoid-type epithelioid granulomas without necrosis, establishing soft tissue sarcoidosis. Further evaluation revealed marked interstitial lung parenchyma lesions and large intrathoracic adenopathies. Bronchofibroscopy with transbronchial biopsy confirmed lung sarcoidosis. In addition, blood analysis showed monoclonal IgG kappa gammopathy. A bone marrow biopsy confirmed hypercellularity with 60% plasma cells and plasmocyte infiltration. Thus, the diagnosis of systemic sarcoidosis and multiple myeloma was established simultaneously. In a brief review of the literature, we identified 33 reports of cases with both sarcoidosis and multiple myeloma. We point out the importance of a high level of suspicion for the association of sarcoidosis with malignant haematological diseases such as multiple myeloma.info:eu-repo/semantics/publishedVersio
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