149 research outputs found
The Orbiting Astrophysical Spectrometer In Space (OASIS)
The Orbiting Astrophysical Observatory In Space (OASIS) is an Advanced Concept currently under study at NASA as a mission for the next decade. The goal of the OASIS mission is to identify a local site or sites where galactic cosmic rays (GCR) originate and are accelerated. The mission will also allow GCR data to be used to investigate how elements are made and distributed in the galaxy and to improve our understanding of supernovae and the nucleosynthesis of the heavy elements. OASIS consists of two instruments that provide complementary data on the location and nature of the source(s) through investigating the composition of ultra-heavy nuclei ( ) and the energy spectrum of electrons.
In particular OASIS will measure the relative abundances in the actinide group ( ) to determine the age of the -process material in GCRs. The presence of young r-process material would indicate that GCRs are a sample of the interstellar
medium in OB associations. OASIS will measure the electron spectrum to 10 TeV. The energy where this spectrum ends will tell us the distance to the nearest GCR source(s). OASIS will look for spectral features and anisotropy in the high energy electron spectrum that are expected to appear when only a few of the nearest astrophysical sources can contribute to the electron flux. Spectral features may also suggest dark matter decay products. We anticipate that these
measurements will lead to the identification of the nearest cosmic ray electron source and provide a crucial test of the OB association model for the origin of GCR nuclei
Maned wolves retain moderate levels of genetic diversity and gene flow despite drastic habitat fragmentation
The maned wolf Chrysocyon brachyurus is the largest South American canid and categorized as Near Threatened on the IUCN Red List. The major threat to conservation efforts is the drastic reduction of suitable habitat for the species. A large portion of its range has been converted into farm and ranch lands as well as urban areas. To better understand the impact that these anthropogenic activities are having over the remaining populations across their current distribution range, we evaluated patterns of genetic variability and differentiation between them. We also compared these results with those obtained from captive maned wolves in order to make proper ex situ recommendations. We cross-amplified 12 microsatellite loci in maned wolf samples collected throughout their range (from Argentina, Brazil, Uruguay and Bolivia) and from captive stocks (from captive breeding centers and zoos in Brazil, Argentina and the USA). We found that
wild populations retain moderate levels of genetic variability compared with other microsatellite studies on wild canids, and our structure analysis revealed 2 genetic clusters in wild samples, one of which included samples exclusively from Bolivia. This cluster could represent a different management unit with conservation priority. The captive stock population showed higher levels of genetic variability, with the ones from Brazil being the most genetically diverse stock. The USA stock showed strong genetic differences with all other groups. This is the first study to examine the patterns of genetic diversity of both wild and captive populations of maned wolves. These results should be incorporated into further population viability assessments and in the Maned Wolf Species Survival Plan.Agencia Nacional de Investigación e Innovació
Emission of volatile halogenated compounds, speciation and localization of bromine and iodine in the brown algal genome model Ectocarpus siliculosus
This study explores key features of bromine and iodine metabolism in the filamentous brown alga and genomics model Ectocarpus siliculosus. Both elements are accumulated in Ectocarpus, albeit at much lower concentration factors (2-3 orders of magnitude for iodine, and < 1 order of magnitude for bromine) than e.g. in the kelp Laminaria digitata. Iodide competitively reduces the accumulation of bromide. Both iodide and bromide are accumulated in the cell wall (apoplast) of Ectocarpus, with minor amounts of bromine also detectable in the cytosol. Ectocarpus emits a range of volatile halogenated compounds, the most prominent of which by far is methyl iodide. Interestingly, biosynthesis of this compound cannot be accounted for by vanadium haloperoxidase since the latter have not been found to catalyze direct halogenation of an unactivated methyl group or hydrocarbon so a methyl halide transferase-type production mechanism is proposed
Characterization of Buriti (Mauritia flexuosa) Foam for Thermal Insulation and Sound Absorption Applications in Buildings
Exploring new construction materials with low environmental impact leads to innovation in buildings and also to the expansion of environmental sustainability in the construction industry. In this perspective, the thermal insulation and the sound absorption performances of Buriti (Mauritia flexuosa) foam were analyzed for potential application in buildings. This material is of plant origin, it is natural, renewable, abundant, and has a low environmental impact. In this research, characterizations were made by scanning electron microscopy (SEM), apparent density, thermogravimetry (TGA and DTG), thermal conductivity, and sound absorption. The SEM analysis revealed a predominantly porous, small, and closed-cell morphology in the vegetable foam. Due to its porosity and lightness, the material has an apparent density similar to other thermal insulating and sound-absorbing materials used commercially. The evaluation of thermogravimetric (TGA/DTG) results demonstrated thermal stability at temperatures that attest to the use of Buriti foam as a building material. Based on the thermal conductivity test, the Buriti foam was characterized as an insulating material comparable to conventional thermal insulation materials and in the same range as other existing thermal insulators of plant origin. Concerning sound absorption, the Buriti foam presented a low performance in the analyzed frequency range, mainly attributed to the absence of open porosity in the material. Therefore, understanding the sound absorption mechanisms of Buriti foam requires further studies exploring additional ways of processing the material
Maned wolves retain moderate levels of genetic diversity and gene flow despite drastic habitat fragmentation
The maned wolf Chrysocyon brachyurus is the largest South American canid and categorized as Near Threatened on the IUCN Red List. The major threat to conservation efforts is the drastic reduction of suitable habitat for the species. A large portion of its range has been converted into farm and ranch lands as well as urban areas. To better understand the impact that these anthropogenic activities are having over the remaining populations across their current distribution range, we evaluated patterns of genetic variability and differentiation between them. We also compared these results with those obtained from captive maned wolves in order to make proper ex situ recommendations. We cross-amplified 12 microsatellite loci in maned wolf samples
collected throughout their range (from Argentina, Brazil, Uruguay and Bolivia) and from captive stocks (from captive breeding centers and zoos in Brazil, Argentina and the USA). We found that wild populations retain moderate levels of genetic variability compared with other microsatellite studies on wild canids, and our structure analysis revealed 2 genetic clusters in wild samples, one of which included samples exclusively from Bolivia. This cluster could represent a different management unit with conservation priority. The captive stock population showed higher levels of genetic variability, with the ones from Brazil being the most genetically diverse stock. The USA stock showed strong genetic differences with all other groups. This is the first study to examine
the patterns of genetic diversity of both wild and captive populations of maned wolves. These results should be incorporated into further population viability assessments and in the Maned Wolf Species Survival Plan
Severe hypoxia induces chemo-resistance in clinical cervical tumors through MVP over-expression
Reproductive biology of the pampas deer (Ozotoceros bezoarticus): a review
The pampas deer (Ozotoceros bezoarticus) is a South American grazing deer which is in extreme danger of extinction. Very little is known about the biology of the pampas deer. Moreover, most information has not been published in peer-reviewed scientific journals, and is only available in local publications, theses, etc. Therefore, our aim was to update and summarize the available information regarding the reproductive biology of the pampas deer. Moreover, in most sections, we have also included new, unpublished information. Detailed descriptions are provided of the anatomy of both the female and the male reproductive tract, puberty onset, the oestrous cycle and gestational length. Birthing and the early postpartum period are described, as are maternal behaviour and early fawn development, seasonal distribution of births, seasonal changes in male reproduction and antler cycle, reproductive behaviour, semen collection, and cryopreservation. Finally, an overview is given and future directions of research are proposed
- …
