342 research outputs found
Sun effects in 2D aperture synthesis radiometry imaging and their cancellation
The Microwave Imaging Radiometer by Aperture
Synthesis (MIRAS) is the single payload of the European Space
Agency’s (ESA) Soil Moisture and Ocean Salinity (SMOS) Earth
Explorer Opportunity mission. MIRAS will be the first two-dimensional
aperture synthesis radiometer for earth observation.
Two-dimensional aperture synthesis radiometers can generate
brightness temperature images by a Fourier synthesis process
without mechanical antenna steering. To do so and have the
necessary wide swath for earth observation, the array is formed by
small and low directive antennas, which do not attenuate enough
bright noise sources that may interfere with the measurements.
This study analyzes the impact of the radio-frequency emission
from the sun in the SMOS mission, reviews the basic image
reconstruction algorithms, and proposes a technique to minimize
sun effects.Postprint (published version
Scavenger guild and consumption patterns of an invasive alien fish species in a Mediterranean wetland
Invasive Alien Species (IAS) alter ecosystems, disrupting ecological processes and driving the loss of ecosystem services. The common carp Cyprinus carpio is a hazardous and widespread IAS, becoming the most abundant species in many aquatic ecosystems. This species transforms ecosystems by accumulating biomass to the detriment of other species, thus altering food webs. However, some terrestrial species, such as vertebrate scavengers, may benefit from dead carps, by incorporating part of the carp biomass into the terrestrial environment. This study describes the terrestrial vertebrate scavenger assemblage that benefits from carp carcasses in a Mediterranean wetland. We also evaluate the seasonal differences in the scavenger assemblage composition and carrion consumption patterns. Eighty carp carcasses (20 per season) were placed in El Hondo Natural Park, a seminatural mesohaline wetland in south-eastern Spain, and we monitored their consumption using camera traps. We recorded 14 scavenger species (10 birds and four mammals) consuming carp carcasses, including globally threatened species. Vertebrates consumed 73% of the carrion biomass and appeared consuming at 82% of the carcasses. Of these carcasses consumed, 75% were completely consumed and the mean consumption time of carcasses completely consumed by vertebrates was 44.4 h (SD = 42.1 h). We recorded differences in species richness, abundance, and assemblage composition among seasons, but we did not find seasonal differences in consumption patterns throughout the year. Our study recorded a rich and efficient terrestrial vertebrate scavenger assemblage benefitting from carp carcasses. We detected a seasonal replacement on the scavenger species, but a maintenance of the ecological function of carrion removal, as the most efficient carrion consumers were present throughout the year. The results highlight the importance of vertebrate scavengers in wetlands, removing possible infectious focus, and moving nutrients between aquatic and terrestrial environments.JMPG was supported by Spanish Ministry of Science, Innovation and Universities contracts (IJC-2019-038968). ESG received the grants PID 2021-124744NA-I00 and RYC2019-027216-I funded by MCIN/AEI/ https://doi.org/10.13039/501100011033 and by ESF Investing in your future
Unravelling the vertebrate scavenger assemblage in the Gobi Desert, Mongolia
Despite the essential role that vertebrate scavengers play in ecosystems, most studies have been conducted in Europe and North America, and there is a lack of information on vertebrate scavengers in vast regions of the world. Our aim was to describe the functioning and composition of the unknown vertebrate scavenger assemblage in the Gobi Desert, Mongolia, and determine how carcass size and habitat type affect species composition and carrion use. We monitored carcasses with camera traps and we also conducted observation points to survey the raptor community and identify the proportion of raptor species making use of the carcasses. We recorded eight vertebrate scavenger species (five birds and three mammals) by camera trap and seven raptors at observation points. Over half of the raptor species recorded at the observation points were also found feeding on carrion. The two most threatened species were only recorded in the mountain habitat. Furthermore, scavenger abundance and consumption rates were higher at large carcasses. This study highlights the importance of scavenging by raptors and other vertebrate scavengers for carrion elimination in ecosystems with extreme climatic conditions.AOT, JMPG, ZMR, LNA and ESG were supported by Generalitat Valenciana (SEJI/2018/024), ZMR and LNA also by contracts co-funded by the Generalitat Valenciana and the European Social Fund (APOSTD/2019/016 and ACIF/2019/056, respectively), and JASZ by funds from the Spanish Ministry of Science, Innovation and Universities and the European Regional Development Fund (RTI 2018-099609-B-C21)
Optimising models for prediction of tropospheric scintillation on satellite links
A phenomenon that also causes impairment in the received signal strength of the RF signal in satellite links operating at frequencies above 10 GHz, especially in those systems that operate at higher frequencies with small fade margins, is the tropospheric scintillation that occurs in the lower layer of the troposphere. In order to estimate the intensity, i.e. the variance between the scintillation amplitude fluctuations, there are several models in the literature, whose accuracy depends on the locality in which the models are implemented. In this Letter, new models are developed for the prediction of tropospheric scintillation that adjusts to localities in Spain, specifically Madrid city, based on measurements of the aforementioned phenomenon reported from Spain and the bios-inspired technique Cuckoo Search (CS). The results obtained, evaluated in terms of the root mean square error, were totally satisfactory, being the most outstanding cases the improved versions of the Ortgies-T, Statistical Temperature and Humidity 2 and Statistical Temperature and Refractivity 2 models
Quiste hidatídico cerebral: a propósito de un caso
La hidatidosis es una parasitosis frecuente en Argentina. La localización más frecuente es la hepática. La presencia de quistes hidatídicos en sistema nervioso central es rara y se da generalmente en edad pediátrica.Facultad de Ciencias Médica
Quiste hidatídico cerebral: a propósito de un caso
La hidatidosis es una parasitosis frecuente en Argentina. La localización más frecuente es la hepática. La presencia de quistes hidatídicos en sistema nervioso central es rara y se da generalmente en edad pediátrica.Facultad de Ciencias Médica
Quiste hidatídico cerebral: a propósito de un caso
La hidatidosis es una parasitosis frecuente en Argentina. La localización más frecuente es la hepática. La presencia de quistes hidatídicos en sistema nervioso central es rara y se da generalmente en edad pediátrica.Facultad de Ciencias Médica
Spanish Cell Therapy Network (TerCel) : 15 years of successful collaborative translational research
In the current article we summarize the 15-year experience of the Spanish Cell Therapy Network (TerCel), a successful collaborative public initiative funded by the Spanish government for the support of nationwide translational research in this important area. Thirty-two research groups organized in three programs devoted to cardiovascular, neurodegenerative and immune-inflammatory diseases, respectively, currently form the network. Each program has three working packages focused on basic science, pre-clinical studies and clinical application. TerCel has contributed during this period to boost the translational research in cell therapy in Spain, setting up a network of Good Manufacturing Practice-certified cell manufacturing facilities- and increasing the number of translational research projects, publications, patents and clinical trials of the participating groups, especially those in collaboration. TerCel pays particular attention to the public-private collaboration, which, for instance, has led to the development of the first allogeneic cell therapy product approved by the European Medicines Agency, Darvadstrocel. The current collaborative work is focused on the development of multicenter phase 2 and 3 trials that could translate these therapies to clinical practice for the benefit of patients
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