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  • Open Access English
    Authors: 
    Ivano Baronchelli; G. Rodighiero; Harry I. Teplitz; Claudia Scarlata; Alberto Franceschini; S. Berta; Laia Barrufet; Mattia Vaccari; Matteo Bonato; Laure Ciesla; +15 more
    Publisher: HAL CCSD
    Countries: France, Italy, United States
    Project: EC | HELP (607254)

    For a sample of star forming galaxies in the redshift interval 0.15$<$z$<$0.3, we study how both the relative strength of the AGN infra-red emission, compared to that due to the star formation (SF), and the numerical fraction of AGNs, change as a function of the total stellar mass of the hosting galaxy group (M$^{*}_{\mathrm{group}}$), between $10^{10.25}$ and $10^{11.9}$M$_{\odot}$. Using a multi-component SED fitting analysis, we separate the contribution of stars, AGN torus and star formation to the total emission at different wavelengths. This technique is applied to a new multi-wavelength data-set in the SIMES field (23 not redundant photometric bands), spanning the wavelength range from the UV (GALEX) to the far-IR (Herschel) and including crucial AKARI and WISE mid-IR observations (4.5 \mu m$<\lambda<$24 \mu m), where the BH thermal emission is stronger. This new photometric catalog, that includes our best photo-z estimates, is released through the NASA/IPAC Infrared Science Archive (IRSA). Groups are identified through a friends of friends algorithm ($\sim$62% purity, $\sim$51% completeness). We identified a total of 45 galaxies requiring an AGN emission component, 35 of which in groups and 10 in the field. We find BHAR$\propto ($M$^{*}_{\mathrm{group}})^{1.21\pm0.27}$ and (BHAR/SFR)$\propto ($M$^{*}_{\mathrm{group}})^{1.04\pm0.24}$ while, in the same range of M$^{*}_{\mathrm{group}}$, we do not observe any sensible change in the numerical fraction of AGNs. Our results indicate that the nuclear activity (i.e. the BHAR and the BHAR/SFR ratio) is enhanced when galaxies are located in more massive and richer groups. Comment: 31 pages, 23 figures

  • Open Access
    Authors: 
    Paul Elzière; Paul Fourton; Quentin Demassieux; Alexis Chennevière; Cécile Dalle-Ferrier; Costantino Creton; Matteo Ciccotti; Etienne Barthel;
    Publisher: American Chemical Society (ACS)
    Country: France

    International audience; For decades, poly(vinylbutyral) (PVB) has been the polymer of choice to improve the impact resistance of laminated glass. PVB presents large rupture strain, large tensile strength and excellent dissipative properties. Here we investigate the relation between macromolecular structure and mechanical properties of plasticised PVB by combining large strain tensile experiments with calorimetry, X-ray and birefringence measurements. We find that the mechanical response is dominated by creep and that this plastic-like flow can effectively be described by a strain dependent viscosity. The commonalities with other toughened polymeric materials are outlined, and especially the role played by phase separated domains with weaker physical bonds. These results could help optimize polymer design for toughness and impact applications.

  • Publication . Article . 2018
    Open Access English
    Authors: 
    Karimi, Shahrzad; Ullrich, Carsten A.; D’Amico, Irene; Perez, Florent;
    Publisher: HAL CCSD
    Countries: France, United Kingdom

    International audience; A two-dimensional electron gas (2DEG) with equal-strength Rashba and Dresselhaus spin-orbit coupling sustains persistent helical spin-wave states, which have remarkably long lifetimes. In the presence of an in-plane magnetic field, there exist single-particle excitations that have the character of propagating helical spin waves. For magnon-like collective excitations, the spin-helix texture reemerges as a robust feature, giving rise to a decoupling of spin-orbit and electronic many-body effects. We prove that the resulting spin-flip wave dispersion is the same as in a magnetized 2DEG without spin-orbit coupling, apart from a shift by the spin-helix wave vector. The precessional mode about the persistent spin-helix state is shown to have an energy given by the bare Zeeman splitting, in analogy with Larmor’s theorem. We also discuss ways to observe the spin-helix Larmor mode experimentally.

  • Open Access English
    Authors: 
    Nizar Bouhlel; Vahid Akbari; Stephane Meric;
    Publisher: HAL CCSD
    Country: France

    International audience; In this article, we propose a determinant ratio test (DRT) statistic to measure the similarity of two covariance matrices for unsupervised change detection in polarimetric radar images. The multilook complex covariance matrix is assumed to follow a scaled complex Wishart distribution. In doing so, we provide the distribution of the DRT statistic that is exactly Wilks's lambda of the second kind distribution, with density expressed in terms of Meijer G-functions. Due to this distribution, the constant false alarm rate (CFAR) algorithm is derived in order to achieve the required performance. More specifically, a threshold is provided by the CFAR to apply to the DRT statistic producing a binary change map. Finally, simulated and real multilook polarimetric SAR (PolSAR) data are employed to assess the performance of the method and is compared with the Hotelling-Lawley trace (HLT) statistic and the likelihood ratio test (LRT) statistic.

  • Publication . Other literature type . Article . 2019
    Open Access English
    Authors: 
    Sara Abednatanzi; Parviz Gohari Derakhshandeh; Hannes Depauw; François-Xavier Coudert; Henk Vrielinck; Pascal Van Der Voort; Karen Leus;
    Publisher: HAL CCSD
    Country: France

    International audience; Mixed-metal MOFs are metal–organic frameworks that contain at least 2 different metal ions as nodes of their frameworks. They are prepared relatively easily by either a one-pot synthesis with a synthesis mixture containing the different metals, or by a post-synthetic ion-exchange method by soaking a monometallic MOF in a concentrated solution of a different (but compatible) metal-ion. More difficult is the accurate characterization of these materials. Is the formed product a mixture of monometallic MOFs or indeed a MOF with different metallic nodes? Are the metals randomly distributed or do they form domains? What is the oxidation state of the metals? How do the metals mutually influence each other, and impact the material's performance? Advanced characterization techniques are required e.g. X-ray absorption spectroscopy, magnetic resonance and electron microscopy. Computational tools at multiple scales are also often applied. In almost every case, a judicious choice of several techniques is required to unambiguously characterize the mixed-metal MOF. Although still in their infancy, several applications are emerging for mixed-metal MOFs, that improve on conventional monometallic MOFs. In the field of gas sorption and storage, especially the stability and affinity towards the target gases can be largely improved by introducing a second metal ion. In the case of flexible MOFs, the breathing behavior, and in particular the pressure at which the MOF opens, can be tailored. In heterogeneous catalysis, new cascade and tandem reactions become possible, with particular focus on reactions where the two metals in close proximity truly form a mixed-metal transition state. The bimetallic MOF should have a clear benefit over a mixture of the respective monometallic MOFs, and bimetallic enzymes can be a huge source of inspiration in this field. Another very promising application lies in the fields of luminescence and sensing. By tuning the lanthanide metals in mixed-metal lanthanide MOFs and by using the organic linkers as antennae, novel smart materials can be developed, acting as sensors and as thermochromic thermometers. Of course there are also still open challenges, as also mixed-metal MOFs do not escape the typical drawbacks of MOFs, such as low stability in moisture and possible metal leaching in liquids. The ease of synthesis of mixed-metal MOFs is a large bonus. In this critical review, we discuss in detail the synthesis, characterization, computational work and applications of mixed-metal MOFs.

  • Open Access
    Authors: 
    Sandrine Bony; Hauke Schulz; Jessica Vial; Bjorn Stevens;
    Publisher: American Geophysical Union (AGU)
    Country: France
    Project: EC | EUREC4A (694768), EC | CONSTRAIN (820829)

    Abstract Trade‐wind clouds exhibit a large diversity of spatial organizations at the mesoscale. Over the tropical western Atlantic, a recent study has visually identified four prominent mesoscale patterns of shallow convection, referred to as flowers, fish, gravel, and sugar. We show that these four patterns can be identified objectively from satellite observations by analyzing the spatial distribution of infrared brightness temperatures. By applying this analysis to 19 years of data, we examine relationships between cloud patterns and large‐scale environmental conditions. This investigation reveals that on daily and interannual timescales, the near‐surface wind speed and the strength of the lower‐tropospheric stability discriminate the occurrence of the different organization patterns. These results, combined with the tight relationship between cloud patterns, low‐level cloud amount, and cloud‐radiative effects, suggest that the mesoscale organization of shallow clouds might change under global warming. The role of shallow convective organization in determining low‐cloud feedback should thus be investigated. Key Points Prominent mesoscale patterns of shallow convection are identified from satellite observationsMesoscale patterns exhibit strong relationships with surface wind speed and lower‐tropospheric stabilityOwing to their differences in low‐cloud fraction, mesoscale patterns exert different impacts on the top‐of‐atmosphere radiation budget

  • Publication . Article . Other literature type . Research . Preprint . 2021
    Open Access
    Authors: 
    Ayse Polatoz; Willard Johns; Sinan Sagir; Soureek Mitra; Michael Tytgat; Ram Krishna Dewanjee; Austin Baty; Graham Wilson; Attilio Santocchia; Erhan Gülmez; +552 more
    Countries: United Kingdom, Spain, Italy, Croatia, Serbia, United States, Turkey, Italy, France, Croatia ...
    Project: EC | AMVA4NewPhysics (675440), EC | INSIGHTS (765710), EC | LHCTOPVLQ (752730)

    Evidence for Higgs boson decay to a pair of muons is presented. This result combines searches in four exclusive categories targeting the production of the Higgs boson via gluon fusion, via vector boson fusion, in association with a vector boson, and in association with a top quark-antiquark pair. The analysis is performed using proton-proton collision data at s√ = 13 TeV, corresponding to an integrated luminosity of 137 fb−1, recorded by the CMS experiment at the CERN LHC. An excess of events over the back- ground expectation is observed in data with a significance of 3.0 standard deviations, where the expectation for the standard model (SM) Higgs boson with mass of 125.38 GeV is 2.5. The combination of this result with that from data recorded at s√ = 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.7 fb−1, respectively, increases both the expected and observed significances by 1%. The measured signal strength, relative to the SM prediction, is 1.19+0.40−0.39(stat)+0.15−0.14(syst). This result constitutes the first evidence for the decay of the Higgs boson to second generation fermions and is the most precise measurement of the Higgs boson coupling to muons reported to date. Individuals have received support from the Marie-Curie programme and the European Research Council and Horizon 2020 Grant, contract Nos. 675440, 752730, and 765710 (European Union); the Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509 and the Programa Severo Ochoa del Principado de Asturias. CMS collaboration: et al. Peer reviewed

  • Open Access English
    Authors: 
    Bijan Nouri; Pascal Moritz Kuhn; Stefan Wilbert; Natalie Hanrieder; Christoph Prahl; Luis F. Zarzalejo; Andreas Kazantzidis; Philippe Blanc; Robert Pitz-Paal;
    Countries: Germany, France

    International audience; Solar irradiance nowcasts can be derived with sky images from all sky imagers (ASI) by detecting and analyzing transient clouds, which are the main contributor of intra-hour solar irradiance variability. The accuracy of ASI based solar irradiance nowcasting systems depends on various processing steps. Two vital steps are the cloud height detection and cloud tracking. This task is challenging, due to the atmospheric conditions that are often complex, including various cloud layers moving in different directions simultaneously.This challenge is addressed by detecting and tracking individual clouds. For this, we developed two distinct ASI nowcasting approaches with four or two cameras and a third hybridized approach. These three systems create individual 3-D cloud models with unique attributes including height, position, size, optical properties and motion. This enables us to describe complex multi-layer conditions.In this paper, derived cloud height and motion vectors are compared with a reference ceilometer (height) and shadow camera system (motion) over a 30 day validation period. The validation data set includes a wide range of cloud heights, cloud motion patterns and atmospheric conditions. Furthermore, limitations of ASI based nowcasting systems due to image resolution and image perspective constrains are discussed.The most promising system is found to be the hybridized approach. This approach uses four ASIs and a voxel carving based cloud modeling combined with a cloud segmentation independent stereoscopic cloud height and tracking detection. We observed for this approach an overall mean absolute error of 648 m for the height, 1.3 m/s for the cloud speed and 16.2° for the motion direction.

  • Publication . Article . Preprint . 2021
    Open Access English
    Authors: 
    Raphaël Tinarrage;
    Country: France

    We propose a definition of persistent Stiefel-Whitney classes of vector bundle filtrations. It relies on seeing vector bundles as subsets of some Euclidean spaces. The usual \v{C}ech filtration of such a subset can be endowed with a vector bundle structure, that we call a \v{C}ech bundle filtration. We show that this construction is stable and consistent. When the dataset is a finite sample of a line bundle, we implement an effective algorithm to compute its persistent Stiefel-Whitney classes. In order to use simplicial approximation techniques in practice, we develop a notion of weak simplicial approximation. As a theoretical example, we give an in-depth study of the normal bundle of the circle, which reduces to understanding the persistent cohomology of the torus knot (1,2). We illustrate our method on several datasets inspired by image analysis. Comment: To appear in Journal of Applied and Computational Topology

  • Open Access English
    Authors: 
    Emma Abernathy; Roberto Mateo; Karim Majzoub; Nicholas van Buuren; Sara W. Bird; Jan E. Carette; Karla Kirkegaard;
    Publisher: HAL CCSD
    Country: France
    Project: NIH | Subversion of Autophagy P... (1R56AI103500-01), NIH | Genetic approaches to dis... (1DP2AI104557-01)

    Author summary Viruses often co-opt host cellular processes to replicate their genomes and spread to other cells. Many of these cellular pathways provide good targets for antiviral drugs, as they are less likely to develop resistance since they are encoded in the host and not the fast-evolving viral genome. The autophagy pathway is an important stress response pathway that allows cells to recycle cellular components for energy conservation by sequestering cytoplasmic molecules and organelles in double-membraned vesicles (DMVs) and by degrading the contents into reusable elements. Many RNA viruses induce this pathway to provide membrane surfaces for replication and as a source of vesicles for maturation and exit from cells. We developed a panel of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) knockout (KO) human cells lacking individual components of the autophagy pathway to assess what aspects of the pathway diverse RNA viruses utilized. We discovered that poliovirus, dengue virus, and Zika virus all use different initiation components of the autophagy pathway but similar downstream components. Additionally, we found that poliovirus uses autophagy components for genome replication, while dengue and Zika viruses use autophagy components for postreplication processes. Ultimately, we uncovered potential drug targets for multiple RNA viruses. Many viruses interface with the autophagy pathway, a highly conserved process for recycling cellular components. For three viral infections in which autophagy constituents are proviral (poliovirus, dengue, and Zika), we developed a panel of knockouts (KOs) of autophagy-related genes to test which components of the canonical pathway are utilized. We discovered that each virus uses a distinct set of initiation components; however, all three viruses utilize autophagy-related gene 9 (ATG9), a lipid scavenging protein, and LC3 (light-chain 3), which is involved in membrane curvature. These results show that viruses use noncanonical routes for membrane sculpting and LC3 recruitment. By measuring viral RNA abundance, we also found that poliovirus utilizes these autophagy components for intracellular growth, while dengue and Zika virus only use autophagy components for post-RNA replication processes. Comparing how RNA viruses manipulate the autophagy pathway reveals new noncanonical autophagy routes, explains the exacerbation of disease by starvation, and uncovers common targets for antiviral drugs.

search
Include:
43,054 Research products, page 1 of 4,306
  • Open Access English
    Authors: 
    Ivano Baronchelli; G. Rodighiero; Harry I. Teplitz; Claudia Scarlata; Alberto Franceschini; S. Berta; Laia Barrufet; Mattia Vaccari; Matteo Bonato; Laure Ciesla; +15 more
    Publisher: HAL CCSD
    Countries: France, Italy, United States
    Project: EC | HELP (607254)

    For a sample of star forming galaxies in the redshift interval 0.15$<$z$<$0.3, we study how both the relative strength of the AGN infra-red emission, compared to that due to the star formation (SF), and the numerical fraction of AGNs, change as a function of the total stellar mass of the hosting galaxy group (M$^{*}_{\mathrm{group}}$), between $10^{10.25}$ and $10^{11.9}$M$_{\odot}$. Using a multi-component SED fitting analysis, we separate the contribution of stars, AGN torus and star formation to the total emission at different wavelengths. This technique is applied to a new multi-wavelength data-set in the SIMES field (23 not redundant photometric bands), spanning the wavelength range from the UV (GALEX) to the far-IR (Herschel) and including crucial AKARI and WISE mid-IR observations (4.5 \mu m$<\lambda<$24 \mu m), where the BH thermal emission is stronger. This new photometric catalog, that includes our best photo-z estimates, is released through the NASA/IPAC Infrared Science Archive (IRSA). Groups are identified through a friends of friends algorithm ($\sim$62% purity, $\sim$51% completeness). We identified a total of 45 galaxies requiring an AGN emission component, 35 of which in groups and 10 in the field. We find BHAR$\propto ($M$^{*}_{\mathrm{group}})^{1.21\pm0.27}$ and (BHAR/SFR)$\propto ($M$^{*}_{\mathrm{group}})^{1.04\pm0.24}$ while, in the same range of M$^{*}_{\mathrm{group}}$, we do not observe any sensible change in the numerical fraction of AGNs. Our results indicate that the nuclear activity (i.e. the BHAR and the BHAR/SFR ratio) is enhanced when galaxies are located in more massive and richer groups. Comment: 31 pages, 23 figures

  • Open Access
    Authors: 
    Paul Elzière; Paul Fourton; Quentin Demassieux; Alexis Chennevière; Cécile Dalle-Ferrier; Costantino Creton; Matteo Ciccotti; Etienne Barthel;
    Publisher: American Chemical Society (ACS)
    Country: France

    International audience; For decades, poly(vinylbutyral) (PVB) has been the polymer of choice to improve the impact resistance of laminated glass. PVB presents large rupture strain, large tensile strength and excellent dissipative properties. Here we investigate the relation between macromolecular structure and mechanical properties of plasticised PVB by combining large strain tensile experiments with calorimetry, X-ray and birefringence measurements. We find that the mechanical response is dominated by creep and that this plastic-like flow can effectively be described by a strain dependent viscosity. The commonalities with other toughened polymeric materials are outlined, and especially the role played by phase separated domains with weaker physical bonds. These results could help optimize polymer design for toughness and impact applications.

  • Publication . Article . 2018
    Open Access English
    Authors: 
    Karimi, Shahrzad; Ullrich, Carsten A.; D’Amico, Irene; Perez, Florent;
    Publisher: HAL CCSD
    Countries: France, United Kingdom

    International audience; A two-dimensional electron gas (2DEG) with equal-strength Rashba and Dresselhaus spin-orbit coupling sustains persistent helical spin-wave states, which have remarkably long lifetimes. In the presence of an in-plane magnetic field, there exist single-particle excitations that have the character of propagating helical spin waves. For magnon-like collective excitations, the spin-helix texture reemerges as a robust feature, giving rise to a decoupling of spin-orbit and electronic many-body effects. We prove that the resulting spin-flip wave dispersion is the same as in a magnetized 2DEG without spin-orbit coupling, apart from a shift by the spin-helix wave vector. The precessional mode about the persistent spin-helix state is shown to have an energy given by the bare Zeeman splitting, in analogy with Larmor’s theorem. We also discuss ways to observe the spin-helix Larmor mode experimentally.

  • Open Access English
    Authors: 
    Nizar Bouhlel; Vahid Akbari; Stephane Meric;
    Publisher: HAL CCSD
    Country: France

    International audience; In this article, we propose a determinant ratio test (DRT) statistic to measure the similarity of two covariance matrices for unsupervised change detection in polarimetric radar images. The multilook complex covariance matrix is assumed to follow a scaled complex Wishart distribution. In doing so, we provide the distribution of the DRT statistic that is exactly Wilks's lambda of the second kind distribution, with density expressed in terms of Meijer G-functions. Due to this distribution, the constant false alarm rate (CFAR) algorithm is derived in order to achieve the required performance. More specifically, a threshold is provided by the CFAR to apply to the DRT statistic producing a binary change map. Finally, simulated and real multilook polarimetric SAR (PolSAR) data are employed to assess the performance of the method and is compared with the Hotelling-Lawley trace (HLT) statistic and the likelihood ratio test (LRT) statistic.

  • Publication . Other literature type . Article . 2019
    Open Access English
    Authors: 
    Sara Abednatanzi; Parviz Gohari Derakhshandeh; Hannes Depauw; François-Xavier Coudert; Henk Vrielinck; Pascal Van Der Voort; Karen Leus;
    Publisher: HAL CCSD
    Country: France

    International audience; Mixed-metal MOFs are metal–organic frameworks that contain at least 2 different metal ions as nodes of their frameworks. They are prepared relatively easily by either a one-pot synthesis with a synthesis mixture containing the different metals, or by a post-synthetic ion-exchange method by soaking a monometallic MOF in a concentrated solution of a different (but compatible) metal-ion. More difficult is the accurate characterization of these materials. Is the formed product a mixture of monometallic MOFs or indeed a MOF with different metallic nodes? Are the metals randomly distributed or do they form domains? What is the oxidation state of the metals? How do the metals mutually influence each other, and impact the material's performance? Advanced characterization techniques are required e.g. X-ray absorption spectroscopy, magnetic resonance and electron microscopy. Computational tools at multiple scales are also often applied. In almost every case, a judicious choice of several techniques is required to unambiguously characterize the mixed-metal MOF. Although still in their infancy, several applications are emerging for mixed-metal MOFs, that improve on conventional monometallic MOFs. In the field of gas sorption and storage, especially the stability and affinity towards the target gases can be largely improved by introducing a second metal ion. In the case of flexible MOFs, the breathing behavior, and in particular the pressure at which the MOF opens, can be tailored. In heterogeneous catalysis, new cascade and tandem reactions become possible, with particular focus on reactions where the two metals in close proximity truly form a mixed-metal transition state. The bimetallic MOF should have a clear benefit over a mixture of the respective monometallic MOFs, and bimetallic enzymes can be a huge source of inspiration in this field. Another very promising application lies in the fields of luminescence and sensing. By tuning the lanthanide metals in mixed-metal lanthanide MOFs and by using the organic linkers as antennae, novel smart materials can be developed, acting as sensors and as thermochromic thermometers. Of course there are also still open challenges, as also mixed-metal MOFs do not escape the typical drawbacks of MOFs, such as low stability in moisture and possible metal leaching in liquids. The ease of synthesis of mixed-metal MOFs is a large bonus. In this critical review, we discuss in detail the synthesis, characterization, computational work and applications of mixed-metal MOFs.

  • Open Access
    Authors: 
    Sandrine Bony; Hauke Schulz; Jessica Vial; Bjorn Stevens;
    Publisher: American Geophysical Union (AGU)
    Country: France
    Project: EC | EUREC4A (694768), EC | CONSTRAIN (820829)

    Abstract Trade‐wind clouds exhibit a large diversity of spatial organizations at the mesoscale. Over the tropical western Atlantic, a recent study has visually identified four prominent mesoscale patterns of shallow convection, referred to as flowers, fish, gravel, and sugar. We show that these four patterns can be identified objectively from satellite observations by analyzing the spatial distribution of infrared brightness temperatures. By applying this analysis to 19 years of data, we examine relationships between cloud patterns and large‐scale environmental conditions. This investigation reveals that on daily and interannual timescales, the near‐surface wind speed and the strength of the lower‐tropospheric stability discriminate the occurrence of the different organization patterns. These results, combined with the tight relationship between cloud patterns, low‐level cloud amount, and cloud‐radiative effects, suggest that the mesoscale organization of shallow clouds might change under global warming. The role of shallow convective organization in determining low‐cloud feedback should thus be investigated. Key Points Prominent mesoscale patterns of shallow convection are identified from satellite observationsMesoscale patterns exhibit strong relationships with surface wind speed and lower‐tropospheric stabilityOwing to their differences in low‐cloud fraction, mesoscale patterns exert different impacts on the top‐of‐atmosphere radiation budget

  • Publication . Article . Other literature type . Research . Preprint . 2021
    Open Access
    Authors: 
    Ayse Polatoz; Willard Johns; Sinan Sagir; Soureek Mitra; Michael Tytgat; Ram Krishna Dewanjee; Austin Baty; Graham Wilson; Attilio Santocchia; Erhan Gülmez; +552 more
    Countries: United Kingdom, Spain, Italy, Croatia, Serbia, United States, Turkey, Italy, France, Croatia ...
    Project: EC | AMVA4NewPhysics (675440), EC | INSIGHTS (765710), EC | LHCTOPVLQ (752730)

    Evidence for Higgs boson decay to a pair of muons is presented. This result combines searches in four exclusive categories targeting the production of the Higgs boson via gluon fusion, via vector boson fusion, in association with a vector boson, and in association with a top quark-antiquark pair. The analysis is performed using proton-proton collision data at s√ = 13 TeV, corresponding to an integrated luminosity of 137 fb−1, recorded by the CMS experiment at the CERN LHC. An excess of events over the back- ground expectation is observed in data with a significance of 3.0 standard deviations, where the expectation for the standard model (SM) Higgs boson with mass of 125.38 GeV is 2.5. The combination of this result with that from data recorded at s√ = 7 and 8 TeV, corresponding to integrated luminosities of 5.1 and 19.7 fb−1, respectively, increases both the expected and observed significances by 1%. The measured signal strength, relative to the SM prediction, is 1.19+0.40−0.39(stat)+0.15−0.14(syst). This result constitutes the first evidence for the decay of the Higgs boson to second generation fermions and is the most precise measurement of the Higgs boson coupling to muons reported to date. Individuals have received support from the Marie-Curie programme and the European Research Council and Horizon 2020 Grant, contract Nos. 675440, 752730, and 765710 (European Union); the Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509 and the Programa Severo Ochoa del Principado de Asturias. CMS collaboration: et al. Peer reviewed

  • Open Access English
    Authors: 
    Bijan Nouri; Pascal Moritz Kuhn; Stefan Wilbert; Natalie Hanrieder; Christoph Prahl; Luis F. Zarzalejo; Andreas Kazantzidis; Philippe Blanc; Robert Pitz-Paal;
    Countries: Germany, France

    International audience; Solar irradiance nowcasts can be derived with sky images from all sky imagers (ASI) by detecting and analyzing transient clouds, which are the main contributor of intra-hour solar irradiance variability. The accuracy of ASI based solar irradiance nowcasting systems depends on various processing steps. Two vital steps are the cloud height detection and cloud tracking. This task is challenging, due to the atmospheric conditions that are often complex, including various cloud layers moving in different directions simultaneously.This challenge is addressed by detecting and tracking individual clouds. For this, we developed two distinct ASI nowcasting approaches with four or two cameras and a third hybridized approach. These three systems create individual 3-D cloud models with unique attributes including height, position, size, optical properties and motion. This enables us to describe complex multi-layer conditions.In this paper, derived cloud height and motion vectors are compared with a reference ceilometer (height) and shadow camera system (motion) over a 30 day validation period. The validation data set includes a wide range of cloud heights, cloud motion patterns and atmospheric conditions. Furthermore, limitations of ASI based nowcasting systems due to image resolution and image perspective constrains are discussed.The most promising system is found to be the hybridized approach. This approach uses four ASIs and a voxel carving based cloud modeling combined with a cloud segmentation independent stereoscopic cloud height and tracking detection. We observed for this approach an overall mean absolute error of 648 m for the height, 1.3 m/s for the cloud speed and 16.2° for the motion direction.

  • Publication . Article . Preprint . 2021
    Open Access English
    Authors: 
    Raphaël Tinarrage;
    Country: France

    We propose a definition of persistent Stiefel-Whitney classes of vector bundle filtrations. It relies on seeing vector bundles as subsets of some Euclidean spaces. The usual \v{C}ech filtration of such a subset can be endowed with a vector bundle structure, that we call a \v{C}ech bundle filtration. We show that this construction is stable and consistent. When the dataset is a finite sample of a line bundle, we implement an effective algorithm to compute its persistent Stiefel-Whitney classes. In order to use simplicial approximation techniques in practice, we develop a notion of weak simplicial approximation. As a theoretical example, we give an in-depth study of the normal bundle of the circle, which reduces to understanding the persistent cohomology of the torus knot (1,2). We illustrate our method on several datasets inspired by image analysis. Comment: To appear in Journal of Applied and Computational Topology

  • Open Access English
    Authors: 
    Emma Abernathy; Roberto Mateo; Karim Majzoub; Nicholas van Buuren; Sara W. Bird; Jan E. Carette; Karla Kirkegaard;
    Publisher: HAL CCSD
    Country: France
    Project: NIH | Subversion of Autophagy P... (1R56AI103500-01), NIH | Genetic approaches to dis... (1DP2AI104557-01)

    Author summary Viruses often co-opt host cellular processes to replicate their genomes and spread to other cells. Many of these cellular pathways provide good targets for antiviral drugs, as they are less likely to develop resistance since they are encoded in the host and not the fast-evolving viral genome. The autophagy pathway is an important stress response pathway that allows cells to recycle cellular components for energy conservation by sequestering cytoplasmic molecules and organelles in double-membraned vesicles (DMVs) and by degrading the contents into reusable elements. Many RNA viruses induce this pathway to provide membrane surfaces for replication and as a source of vesicles for maturation and exit from cells. We developed a panel of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) knockout (KO) human cells lacking individual components of the autophagy pathway to assess what aspects of the pathway diverse RNA viruses utilized. We discovered that poliovirus, dengue virus, and Zika virus all use different initiation components of the autophagy pathway but similar downstream components. Additionally, we found that poliovirus uses autophagy components for genome replication, while dengue and Zika viruses use autophagy components for postreplication processes. Ultimately, we uncovered potential drug targets for multiple RNA viruses. Many viruses interface with the autophagy pathway, a highly conserved process for recycling cellular components. For three viral infections in which autophagy constituents are proviral (poliovirus, dengue, and Zika), we developed a panel of knockouts (KOs) of autophagy-related genes to test which components of the canonical pathway are utilized. We discovered that each virus uses a distinct set of initiation components; however, all three viruses utilize autophagy-related gene 9 (ATG9), a lipid scavenging protein, and LC3 (light-chain 3), which is involved in membrane curvature. These results show that viruses use noncanonical routes for membrane sculpting and LC3 recruitment. By measuring viral RNA abundance, we also found that poliovirus utilizes these autophagy components for intracellular growth, while dengue and Zika virus only use autophagy components for post-RNA replication processes. Comparing how RNA viruses manipulate the autophagy pathway reveals new noncanonical autophagy routes, explains the exacerbation of disease by starvation, and uncovers common targets for antiviral drugs.

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