453 research outputs found
Fluid dipping technology of chimpanzees in Comoé National Park, Ivory Coast
Over a 6 month period during the dry season, from the end of October 2014 to the beginning of May 2015, we studied tool use behavior of previously unstudied and non-habituated savanna chimpanzees (Pan troglodytes verus) living in the Comoé National Park, Ivory Coast (CI). We analyzed all the stick tools and leaf-sponges found that the chimpanzees used to forage for ants, termites, honey, and water. We found a particular behavior to be widespread across different chimpanzee communities in the park, namely, dipping for water from tree holes using sticks with especially long brush-tip modifications, using camera traps, we recorded adults, juveniles, and infants of three communities displaying this behavior. We compared water dipping and honey dipping tools used by Comoé chimpanzees and found significant differences in the total length, diameter, and brush length of the different types of fluid-dipping tools used. We found that water dipping tools had consistently longer and thicker brush-tips than honey dipping tools. Although this behavior was observed only during the late dry season, the chimpanzees always had alternative water sources available, like pools and rivers, in which they drank without the use of a tool. It remains unclear whether the use of a tool increases efficient access to water. This is the first time that water dipping behavior with sticks has been found as a widespread and well-established behavior across different age and sex classes and communities, suggesting the possibility of cultural transmission. It is crucial that we conserve this population of chimpanzees, not only because they may represent the second largest population in the country, but also because of their unique behavioral repertoire
Search for the companions of Galactic SNe Ia
The central regions of the remnants of Galactic SNe Ia have been examined for
the presence of companion stars of the exploded supernovae. We present the
results of this survey for the historical SN 1572 and SN 1006. The spectra of
the stars are modeled to obtain Teff, log g and the metallicity. Radial
velocities are obtained with an accuracy of 5--10 km s. Implications for
the nature of the companion star in SNeIa follow.Comment: 8 pages, 2 Postscript figures. Appeared in "From Twilight to
Highlight: the Physics of Supernovae", ed. W. Hillebrandt & B. Leibundgut
(Springer), pp. 140-14
Optical and near infrared observations of SN 1998bu
Infrared and optical spectra of SN 1998bu at an age of one year after
explosion are presented. The data show evidence for the radioactive decay of
56Co to 56Fe, long assumed to be the powering source for the supernova light
curve past maximum light. The spectra provide direct evidence for at least 0.4
solar masses of iron being present in the ejecta of the supernova. The fits to
the data also show that the widths of the emission lines increase with time.
Photometric measurements in the H-band show that the supernova is not fading
during the observation period. This is consistent with theoretical
expectations.Comment: accepted A&A, 7 pages, 9 figure
Tycho Brahe's supernova: light from centuries past
The light curve of SN 1572 is described in the terms used nowadays to
characterize SNeIa. By assembling the records of the observations done in
1572--74 and evaluating their uncertainties, it is possible to recover the
light curve and the color evolution of this supernova. It is found that, within
the SNe Ia family, the event should have been a SNIa with a normal rate of
decline, its stretch factor being {\it s} 0.9. Visual light curve near
maximum, late--time decline and the color evolution sustain this conclusion.
After correcting for extinction, the luminosity of this supernova is found to
be M --19.58 --5 log (D/3.5 kpc) 0.42.Comment: 28 pages, 3 figures, 3 tables. submitted to ApJ (Main Journal
Type Ia Supernova Scenarios and the Hubble Sequence
The dependence of the Type Ia supernova (SN Ia) rate on galaxy type is
examined for three currently proposed scenarios: merging of a
Chandrasekhar--mass CO white dwarf (WD) with a CO WD companion, explosion of a
sub--Chandrasekhar mass CO WD induced by accretion of material from a He star
companion, and explosion of a sub--Chandrasekhar CO WD in a symbiotic system.
The variation of the SNe Ia rate and explosion characteristics with time is
derived, and its correlation with parent population age and galaxy redshift is
discussed. Among current scenarios, CO + He star systems should be absent from
E galaxies. Explosion of CO WDs in symbiotic systems could account for the SNe
Ia rate in these galaxies. The same might be true for the CO + CO WD scenario,
depending on the value of the common envelope parameter. A testable prediction
of the sub--Chandrasekhar WD model is that the average brightness and kinetic
energy of the SN Ia events should increase with redshift for a given Hubble
type. Also for this scenario, going along the Hubble sequence from E to Sc
galaxies SNe Ia events should be brighter on average and should show larger
mean velocities of the ejecta. The observational correlations strongly suggest
that the characteristics of the SNe Ia explosion are linked to parent
population age. The scenario in which WDs with masses below the Chandrasekhar
mass explode appears the most promising one to explain the observed variation
of the SN Ia rate with galaxy type together with the luminosity--expansion
velocity trend.Comment: 16 pages uuencoded compressed Postscript, 2 figures included. ApJ
Letters, in pres
Identification of the companion stars of Type Ia supernovae
The nature of the binary systems giving rise to Type Ia supernovae (SNeIa)
remains an unsolved problem. In this {\it Letter} we calculate, from the
statistics of initial conditions (masses and binary separations), the mass,
luminosity, and velocity distributions of the possible binary companions
(main-sequence star, subgiant, red giant) following the explosion of the white
dwarf which gives rise to the SNeIa. Those companions could be detected from
either their proper or their radial motions, by means of high-precision
astrometric and radial-velocity measurements in young, nearby supernova
remnants. Peculiar velocities typically ranging from 100 to 450 km s
should be expected, which places proper-motion measurements within reach of HST
instruments and makes radial-velocity ones feasible with 2.5-4m class
telescopes from the ground. Detections would solve the long-standing problem of
which kind of binaries do produce SNeIa and clear up the way to accurate
physical modeling of the explosions.Comment: 17 pages, incl. 2 figures. Submittet to ApJ (Letters
Supernova search at intermediate z. I. Spectroscopic analysis
We study 8 supernovae discovered as part of the International Time Programme
(ITP) project ``Omega and Lambda from Supernovae and the Physics of Supernova
Explosions'' at the European Northern Observatory (ENO). The goal of the
project is to increase the sample of intermediate redshift (0.1<z<0.4) SNe Ia
for testing properties of SNe Ia along z and for enlarging the sample in the
Hubble diagram up to large z.Comment: 2 pages, 2 figures, 1 table, to appear in ``1604-2004: Supernovae as
Cosmological Lighthouses'', (extended text upon request
Evaluation in a Cytokine Storm Model in Vivo of the Safety and Efficacy of Intravenous Administration of PRS CK STORM (Standardized Conditioned Medium Obtained by Coculture of Monocytes and Mesenchymal Stromal Cells)
Our research group has been developing a series of biological drugs produced by cocul-ture techniques with M2-polarized macrophages with different primary tissue cells and/or mesen-chymal stromal cells (MSC), generally from fat, to produce anti-inflammatory and anti-fibrotic ef-fects, avoiding the overexpression of pro-inflammatory cytokines by the innate immune system at a given time. One of these products is the drug PRS CK STORM, a medium conditioned by allogenic M2-polarized macrophages, from coculture, with those macrophages M2 with MSC from fat, whose composition, in vitro safety, and efficacy we studied. In the present work, we publish the results obtained in terms of safety (pharmacodynamics and pharmacokinetics) and efficacy of the intravenous application of this biological drug in a murine model of cytokine storm associated with severe infectious processes, including those associated with COVID-19. The results demonstrate the safety and high efficacy of PRS CK STORM as an intravenous drug to prevent and treat the cytokine storm associated with infectious processes, including COVID-19
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