23 research outputs found
A quantitative measure of internal cavitation in superplastic alloys using photoacoustic analysis
The influence of ethofumesate on the growth and development, chlorophyll and nitrogen content of Lolium perenne L.
QUIJOTE scientific results -- XIII. Intensity and polarization study of supernova remnants in the QUIJOTE-MFI wide survey: CTB 80, Cygnus Loop, HB 21, CTA 1, Tycho and HB 9
International audienceWe use the new QUIJOTE-MFI wide survey (11, 13, 17 and 19 GHz) to produce spectral energy distributions (SEDs), on an angular scale of 1 deg, of the supernova remnants (SNRs) CTB 80, Cygnus Loop, HB 21, CTA 1, Tycho and HB 9. We provide new measurements of the polarized synchrotron radiation in the microwave range. For each SNR, the intensity and polarization SEDs are obtained and modelled by combining QUIJOTE-MFI maps with ancillary data. In intensity, we confirm the curved power law spectra of CTB 80 and HB 21 with a break frequency at 2.0 GHz and 5.0 GHz respectively; and spectral indices respectively below and above the spectral break of and for CTB 80, and and for HB 21. In addition, we provide upper limits on the Anomalous Microwave Emission (AME), suggesting that the AME contribution is negligible towards these remnants. From a simultaneous intensity and polarization fit, we recover synchrotron spectral indices as flat as , and the whole sample has a mean and scatter of . The polarization fractions have a mean and scatter of %. When combining our results with the measurements from other QUIJOTE studies of SNRs, we find that radio spectral indices are flatter for mature SNRs, and particularly flatter for CTB 80 () and HB 21 (). In addition, the evolution of the spectral indices against the SNRs age is modelled with a power-law function, providing an exponent and amplitude (normalised at 10 kyr), which are conservative with respect to previous studies of our Galaxy and the Large Magellanic Cloud
QUIJOTE scientific results -- XIII. Intensity and polarization study of supernova remnants in the QUIJOTE-MFI wide survey: CTB 80, Cygnus Loop, HB 21, CTA 1, Tycho and HB 9
International audienceWe use the new QUIJOTE-MFI wide survey (11, 13, 17 and 19 GHz) to produce spectral energy distributions (SEDs), on an angular scale of 1 deg, of the supernova remnants (SNRs) CTB 80, Cygnus Loop, HB 21, CTA 1, Tycho and HB 9. We provide new measurements of the polarized synchrotron radiation in the microwave range. For each SNR, the intensity and polarization SEDs are obtained and modelled by combining QUIJOTE-MFI maps with ancillary data. In intensity, we confirm the curved power law spectra of CTB 80 and HB 21 with a break frequency at 2.0 GHz and 5.0 GHz respectively; and spectral indices respectively below and above the spectral break of and for CTB 80, and and for HB 21. In addition, we provide upper limits on the Anomalous Microwave Emission (AME), suggesting that the AME contribution is negligible towards these remnants. From a simultaneous intensity and polarization fit, we recover synchrotron spectral indices as flat as , and the whole sample has a mean and scatter of . The polarization fractions have a mean and scatter of %. When combining our results with the measurements from other QUIJOTE studies of SNRs, we find that radio spectral indices are flatter for mature SNRs, and particularly flatter for CTB 80 () and HB 21 (). In addition, the evolution of the spectral indices against the SNRs age is modelled with a power-law function, providing an exponent and amplitude (normalised at 10 kyr), which are conservative with respect to previous studies of our Galaxy and the Large Magellanic Cloud
QUIJOTE Scientific Results -- XVII. Studying the Anomalous Microwave Emission in the Andromeda Galaxy with QUIJOTE-MFI
International audienceThe Andromeda Galaxy (M31) is the Local Group galaxy that is most similar to the Milky Way (MW). The similarities between the two galaxies make M31 useful for studying integrated properties common to spiral galaxies. We use the data from the recent QUIJOTE-MFI Wide Survey, together with new raster observations focused on M31, to study its integrated emission. The addition of raster data improves the sensitivity of QUIJOTE-MFI maps by a factor greater than 3. Our main interest is to confirm if anomalous microwave emission (AME) is present in M31, as previous studies have suggested. To do so, we built the integrated spectral energy distribution of M31 between 0.408 and 3000 GHz. We then performed a component separation analysis taking into account synchrotron, free-free, AME and thermal dust components. AME in M31 is modelled as a log-normal distribution with maximum amplitude, , equal to Jy. It peaks at GHz with a width of . Both the Akaike and Bayesian Information Criteria find the model without AME to be less than 1 % as probable as the one taking AME into consideration, thus strongly favouring the presence of AME in M31. We find that the AME emissivity in M31 is K/(MJy/sr), similar to that computed for the MW. We also provide the first upper limits for the AME polarization fraction in an extragalactic object. M31 remains the only galaxy where an AME measurement has been made of its integrated spectrum
QUIJOTE Scientific Results -- XVII. Studying the Anomalous Microwave Emission in the Andromeda Galaxy with QUIJOTE-MFI
International audienceThe Andromeda Galaxy (M31) is the Local Group galaxy that is most similar to the Milky Way (MW). The similarities between the two galaxies make M31 useful for studying integrated properties common to spiral galaxies. We use the data from the recent QUIJOTE-MFI Wide Survey, together with new raster observations focused on M31, to study its integrated emission. The addition of raster data improves the sensitivity of QUIJOTE-MFI maps by a factor greater than 3. Our main interest is to confirm if anomalous microwave emission (AME) is present in M31, as previous studies have suggested. To do so, we built the integrated spectral energy distribution of M31 between 0.408 and 3000 GHz. We then performed a component separation analysis taking into account synchrotron, free-free, AME and thermal dust components. AME in M31 is modelled as a log-normal distribution with maximum amplitude, , equal to Jy. It peaks at GHz with a width of . Both the Akaike and Bayesian Information Criteria find the model without AME to be less than 1 % as probable as the one taking AME into consideration, thus strongly favouring the presence of AME in M31. We find that the AME emissivity in M31 is K/(MJy/sr), similar to that computed for the MW. We also provide the first upper limits for the AME polarization fraction in an extragalactic object. M31 remains the only galaxy where an AME measurement has been made of its integrated spectrum
Possibility for reverse zoonotic transmission of sars-cov-2 to free-ranging wildlife: A case study of bats
10.1371/journal.ppat.1008758PLoS Pathogens169e100875
On Bayesian analysis of mixtures with an unknown number of components - Discussion
New methodology for fully Bayesian mixture analysis is developed, making use of reversible jump Markov chain Monte Carlo methods that are capable of jumping between the parameter subspaces corresponding to different numbers of components in the mixture. A sample from the full joint distribution of all unknown variables is thereby generated, and this can be used as a basis for a thorough presentation of many aspects of the posterior distribution. The methodology is applied here to the analysis of univariate normal mixtures, using a hierarchical prior model that offers an approach to dealing with weak prior information while avoiding the mathematical pitfalls of using improper priors in the mixture context