65 research outputs found
Six priorities to advance the science and practice of coral reef restoration worldwide
Coral reef restoration is a rapidly growing movement galvanized by the accelerating degradation of the world's tropical coral reefs. The need for concerted and collaborative action focused on the recovery of coral reef ecosystems coalesced in the creation of the Coral Restoration Consortium (CRC) in 2017. In March 2020, the CRC leadership team met for a biennial review of international coral reef restoration efforts and a discussion of perceived knowledge and implementation bottlenecks that may impair scalability and efficacy. Herein we present six priorities wherein the CRC will foster scientific advancement and collaboration to: (1) increase restoration efficiency, focusing on scale and cost-effectiveness of deployment; (2) scale up larval-based coral restoration efforts, emphasizing recruit health, growth, and survival; (3) ensure restoration of threatened coral species proceeds within a population-genetics management context; (4) support a holistic approach to coral reef ecosystem restoration; (5) develop and promote the use of standardized terms and metrics for coral reef restoration; and (6) support coral reef restoration practitioners working in diverse geographic locations. These priorities are not exhaustive nor do we imply that accomplishing these tasks alone will be sufficient to restore coral reefs globally; rather these are topics where we feel the CRC community of practice can make timely and significant contributions to facilitate the growth of coral reef restoration as a practical conservation strategy. The goal for these collective actions is to provide tangible, local-scale advancements in reef condition that offset declines resulting from local and global stressors including climate change
Targeted proteomics links virulence factor expression with clinical severity in staphylococcal pneumonia
IntroductionThe bacterial pathogen Staphylococcus aureus harbors numerous virulence factors that impact infection severity. Beyond virulence gene presence or absence, the expression level of virulence proteins is known to vary across S. aureus lineages and isolates. However, the impact of expression level on severity is poorly understood due to the lack of high-throughput quantification methods of virulence proteins.MethodsWe present a targeted proteomic approach able to monitor 42 staphylococcal proteins in a single experiment. Using this approach, we compared the quantitative virulomes of 136 S. aureus isolates from a nationwide cohort of French patients with severe community-acquired staphylococcal pneumonia, all requiring intensive care. We used multivariable regression models adjusted for patient baseline health (Charlson comorbidity score) to identify the virulence factors whose in vitro expression level predicted pneumonia severity markers, namely leukopenia and hemoptysis, as well as patient survival.ResultsWe found that leukopenia was predicted by higher expression of HlgB, Nuc, and Tsst-1 and lower expression of BlaI and HlgC, while hemoptysis was predicted by higher expression of BlaZ and HlgB and lower expression of HlgC. Strikingly, mortality was independently predicted in a dose-dependent fashion by a single phage-encoded virulence factor, the Panton-Valentine leucocidin (PVL), both in logistic (OR 1.28; 95%CI[1.02;1.60]) and survival (HR 1.15; 95%CI[1.02;1.30]) regression models.DiscussionThese findings demonstrate that the in vitro expression level of virulence factors can be correlated with infection severity using targeted proteomics, a method that may be adapted to other bacterial pathogens
Statement on a conceptual framework for the risk assessment of certain food additives re-evaluated under Commission Regulation (EU) No 257/2010
The Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific statement presenting a conceptual framework for the risk assessment of certain food additives re-evaluated under Commission Regulation (EU) No 257/2010. This framework will be used in the evaluation made by the Panel, but the expert judgement of the scientific background, on a case-by-case basis, remains essential to reach a final conclusion. The outcome of the re-evaluation of food additives taking into account all available information is presented in the document, as well as the exposure assessment scenarios to be carried out by the Panel considering the use levels set in the legislation and the availability of adequate usage or analytical data
Six priorities to advance the science and practice of coral reef restoration worldwide
Coral reef restoration is a rapidly growing movement galvanized by the accelerating degradation of the world's tropical coral reefs. The need for concerted and collaborative action focused on the recovery of coral reef ecosystems coalesced in the creation of the Coral Restoration Consortium (CRC) in 2017. In March 2020, the CRC leadership team met for a biennial review of international coral reef restoration efforts and a discussion of perceived knowledge and implementation bottlenecks that may impair scalability and efficacy. Herein we present six priorities wherein the CRC will foster scientific advancement and collaboration to: (1) increase restoration efficiency, focusing on scale and cost-effectiveness of deployment; (2) scale up larval-based coral restoration efforts, emphasizing recruit health, growth, and survival; (3) ensure restoration of threatened coral species proceeds within a population-genetics management context; (4) support a holistic approach to coral reef ecosystem restoration; (5) develop and promote the use of standardized terms and metrics for coral reef restoration; and (6) support coral reef restoration practitioners working in diverse geographic locations. These priorities are not exhaustive nor do we imply that accomplishing these tasks alone will be sufficient to restore coral reefs globally; rather these are topics where we feel the CRC community of practice can make timely and significant contributions to facilitate the growth of coral reef restoration as a practical conservation strategy. The goal for these collective actions is to provide tangible, local-scale advancements in reef condition that offset declines resulting from local and global stressors including climate change
Coexistence of genetically modified (GM) and non-GM crops in the European Union. A review
Non, ce n'est pas la fin du chef de publicité
Nein, dies bedeutet nicht die Entlassung des Werbechefs !
Indem er einen Artikel beantwortet, der in "Printer's Ink" unter dem Titel "Befindet sich der Werbechef auf dem absteigenden Ast"?, gibt der Verfasser die GrĂŒnde an, die ihm Veranlassung dazu geben, den Werbechef einer Agentur als einen fĂŒr die Werbeherstellung unbedingt notwendigen Leiter anzusehen, wobei er gleichzeitit vor der gesetzlosen Unordnung warnt, die eine Folge seines Verschwindens sein wĂŒrde.No, the account executive is not finished
Replying to an article which appeared in "Printer's Ink" under the title "Is the Account Executive on his way out?", the writer gives his reasons for comparing the Account Executive with an orchestral conducter indispensible in advertising production. At the same time he warns us of the chaos which would follow upon the Account Executive's disappearance.RĂ©pondant Ă un article publiĂ© dans « Printer's Ink » sous le titre « Le chef de publicitĂ© est-il en dĂ©clin? », l'auteur prĂ©cise les raisons qui lui font considĂ©rer le chef de publicitĂ© d'agence comme un chef d'orchestre indispensable Ă la production publicitaire, mettant en garde du mĂȘme coup contre l'anarchie qui rĂ©sulterait de sa disparition.Pivard Renaud. Non, ce n'est pas la fin du chef de publicitĂ©. In: Les Cahiers de la publicitĂ©, n°2, Les avenirs de la publicitĂ©. 1re partie : Les interrogations. pp. 119-123
Staphylococcus aureus virulence factors implicated in community-acquired pneumonia : focus on the gamma-hemolysin
Staphylococcus aureus est une bactĂ©rie responsable de nombreuses infections, dont les pneumonies, le plus souvent dâacquisition nosocomiale mais aussi communautaire. Ces derniĂšres sont rares mais souvent graves, avec un fort taux de mortalitĂ©. La Leucocidine de Panton-Valentin (PVL) est une toxine de S. aureus connue pour participer Ă sa virulence dans ce contexte de pneumonie, et bien quâayant un rĂŽle majeur dans la sĂ©vĂ©ritĂ© des pneumonies communautaires (PC), la PVL nâest pas prĂ©sente dans lâensemble des souches responsables de PC. Ceci implique que dâautres facteurs de virulence contribuent Ă la sĂ©vĂ©ritĂ©. Un premier objectif de mes travaux a Ă©tĂ© de rechercher les diffĂ©rents facteurs de virulence impliquĂ©s de maniĂšre dose-dĂ©pendante dans les PC sĂ©vĂšres grĂące Ă une approche de protĂ©omique ciblĂ©e explorant 136 isolats cliniques. Cette Ă©tude a permis de dĂ©montrer que la PVL est le principal facteur de la virulence de S. aureus, corrĂ©lĂ© de maniĂšre dose-dĂ©pendante avec le dĂ©cĂšs. NĂ©anmoins, en plus de la PVL, dâautres facteurs participent Ă la sĂ©vĂ©ritĂ© des infections, notamment lâhĂ©molysine-g CB (HlgCB), qui fonctionne et cible les mĂȘmes cellules que la PVL. Le second objectif de ces travaux a donc Ă©tĂ© dâĂ©tudier le rĂŽle dâHlgCB dans les pneumonies et dâĂ©tudier les mĂ©canismes de rĂ©gulations de son expression dans des souches cliniques. Nos rĂ©sultats ont pu montrer que cette toxine participe Ă la virulence de S. aureus. De plus, lâĂ©tude de sa production dans diffĂ©rentes souches cliniques, via diffĂ©rentes approches de biologie molĂ©culaire, a montrĂ© lâexistence de deux profils distincts en plus dâune forte variabilitĂ© dâexpression inter-souche. Ces diffĂ©rences sâexpliquent par des diffĂ©rences dâactivitĂ© promotrice, de stabilitĂ© des ARN et de traductibilitĂ©, dĂ» Ă la prĂ©sence de single nucleotide polymorphims (SNPs), notamment dans la rĂ©gion 5â- UnTranslated Region (5â-UTR). Enfin, malgrĂ© une organisation en opĂ©ron dâHlgCB, plusieurs transcrits plus courts, certains correspondant Ă hlgB seul, et dâautres Ă un transcrit plus court quâhlgB, nommĂ© short hlgB (shlgB), ont Ă©tĂ© dĂ©couverts. Leurs rĂŽles et mĂ©canismes de productions ont Ă©tĂ© investiguĂ©s, mais restent encore Ă approfondir. Ces travaux ont donc permis de confirmer le rĂŽle de la PVL dans la virulence de S. aureus dans un contexte de pneumonie, mais Ă©galement celui dâHlgCB, cette derniĂšre Ă©tant trĂšs finement rĂ©gulĂ©e.Staphylococcus aureus is a bacterium responsible for many infections, including pneumonia, most often acquired nosocomial but also community acquired. The latter are rare but often serious, with a high mortality rate. Several virulence factors of S. aureus are known to contribute to its virulence, notably the Panton-Valentin Leucocidin (PVL). Although PVL plays a major role in the severity of community-acquired pneumonia (CAP), it is not present in all S. aureus strains causing pneumonia, implying that other virulence factors contribute to severity. A first objective of my work was to investigate the different virulence factors involved in a dose-dependent manner in severe CAP using a targeted proteomics approach on 136 clinical isolates. This study demonstrated that PVL is the main virulence factor of S. aureus, correlated in a dose-dependent manner with death. However, in addition to PVL, other factors are involved in the severity of infections, notably the g-hemolysin CB (HlgCB), which similarly works and targets the same cells as PVL. The second objective of this work was therefore to study the role of HlgCB in pneumonia and to study the mechanisms regulating its expression in clinical strains. Our results showed that this toxin participates in the virulence of S. aureus, particularly in PVL-negative strains. Moreover, the study of its production in different clinical strains, using different molecular biology approaches, showed the existence of two distinct profiles in addition to a high variability of inter-strain expression. These differences can be explained by differences in promoter activity, RNA stability and translatability, due to sequence differences, and in particular the presence of single nucleotide polymorphisms (SNPs) in the 5'- Untranslated Region (5'-UTR). Finally, despite an operon-like organization of HlgCB, several shorter transcripts, some corresponding to hlgB alone, and others to a transcript shorter than hlgB, named short hlgB (shlgB), have been discovered. Their roles and mechanisms of production have been investigated but remain to be further studied
Spectroscopie UV à Double Peigne de Fréquence (dual comb) en vue de l'étude de la molécule OH
The atmospheric gas phase evolution is of main concern for air quality and climate evolution, as indicated in the recent IPPC Report [1]. In this context, the radical OH has been recognized as one of the key molecule in the atmosphere, participating for instance to 90 % of the atmospheric methane loss. The radical OH interactions in the atmosphere remain not fully understood, as it is very challenging to measure. To improve the understanding of the role of OH in the atmosphere, there is a need for instruments that should be sensitive, accurate, and have a fast acquisition time in the timeframe of the OH lifetime (ms). We propose to extend the already existing dual comb spectroscopy (DCS) methodology instrument from the IR [2,3] to the near UV region to take advantage of the strong absorption cross-section of OH at 308 nm. Numerical and theoretical work [4] effectively assess the feasibility of the DCS method in the UV range. This study concludes that the TiSa Kerr lens mode-locked laser source appears to be the most adapted laser source to realize DCS in the UV. The advantages of the remote sensing DCS method are multiple: it is a fast acquisition rate with similar sensitivity than the existing spectroscopic methods, it is an in-situ method, free of sampling retrieval and free of atmospheric fluctuations. A homemade DCS laser source has been fully realized in the laboratory with an original geometry. It consists in a single ring cavity laser generating two pulses trains of 100 fs. This geometry is advantageous for DCS as it allows a common noise sharing (amplitude and phase). The total mode-locked emitted output power reaches 700 mW with 5.5 W pump power, which would provide enough power to probe atmospheric molecules with UV-DCS via third harmonic generation. The first tests of the DCS experiment using our homemade laser source have been realized on Fabry-Perot (FP) and O2 molecules. We retrieved accurately the free spectral range of the FP and obtained, with high accuracy, the ro-vibrational transitions position of O2 at 760 nm. We demonstrated that the here developed single cavity laser source provides high enough relative phase stability (at least 330 ms) between the two laser emissions. These first results represent an important milestone towards atmospheric trace gases remote sensing using UV-DCS. [1] IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. PĂ©an, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press [2] Rieker, G. B., Giorgetta, F. R., Coddington, I., Swann, W. C., Sinclair, L. C., Cromer, C. L., ... & Newbury, N. R. (2013, November). Dual-comb spectroscopy of greenhouse gases over a 2-km outdoor path. In Optical Instrumentation for Energy and Environmental Applications (pp. ET2A-2). Optical Society of America. [3] Coburn, S., Alden, C. B., Wright, R., Cossel, K., Baumann, E., Truong, G. W., ... & Rieker, G. B. (2018). Regional trace-gas source attribution using a field-deployed dual frequency comb spectrometer. Optica, 5(4), 320-327. [4] Galtier, S., Pivard, C., & Rairoux, P. (2020). Towards DCS in the UV Spectral Range for Remote Sensing of Atmospheric Trace Gases. Remote Sensing, 12(20), 3444.L'Ă©volution de la phase gazeuse atmosphĂ©rique est une prĂ©occupation majeure pour la qualitĂ© de l'air et l'Ă©volution du climat, comme indiquĂ© dans le rĂ©cent rapport du GIEC [1]. Dans ce contexte, le radical OH a Ă©tĂ© reconnu comme l'une des molĂ©cules clĂ©s de l'atmosphĂšre, participant par exemple Ă 90 % de la rĂ©duction de mĂ©thane atmosphĂ©rique. Les interactions radicalaires OH dans l'atmosphĂšre ne sont pas encore entiĂšrement comprises car elles sont trĂšs difficiles Ă mesurer. Pour amĂ©liorer la comprĂ©hension du rĂŽle de l'OH dans l'atmosphĂšre, il existe un besoin d'instruments qui doivent ĂȘtre sensibles, prĂ©cis et avoir un temps d'acquisition rapide dans la durĂ©e de vie de l'OH (ms). Nous proposons d'Ă©tendre la mĂ©thode de spectroscopie Ă double peigne de frĂ©quence (DCS) dĂ©jĂ existant dans l'IR [2,3] Ă la rĂ©gion proche UV afin de tirer parti de la forte section efficace d'absorption de OH Ă 308 nm. Une Ă©tude numĂ©rique et thĂ©orique [4] a Ă©valuĂ© efficacement la faisabilitĂ© de la mĂ©thode DCS dans le domaine UV. Cette Ă©tude conclut que la source laser Ti:sa Ă verrouillage de mode par effet Kerr semble ĂȘtre la source laser la plus adaptĂ©e pour rĂ©aliser le DCS dans l'UV. Les avantages de la mĂ©thode DCS pour la tĂ©lĂ©dĂ©tection sont multiples : vitesse d'acquisition rapide avec une sensibilitĂ© similaire aux mĂ©thodes spectroscopiques existantes, c'est une mĂ©thode in-situ, sans prĂ©lĂšvement d'Ă©chantillons et indĂ©pendant des fluctuations atmosphĂ©riques. Une source laser DCS a Ă©tĂ© entiĂšrement rĂ©alisĂ©e en laboratoire avec une gĂ©omĂ©trie originale. Il consiste en un laser Ă cavitĂ© en anneau unique gĂ©nĂ©rant deux trains d'impulsions de 100 fs. Cette gĂ©omĂ©trie est avantageuse pour la mĂ©thode DCS car elle permet un partage des bruits commun (amplitude et phase) aux deux impulsions.La puissance totale Ă©mise du laser Ă mode verrouillĂ© atteint 700 mW avec une puissance de pompe de 5,5 W, ce qui fournit suffisamment de puissance pour sonder les molĂ©cules atmosphĂ©riques par UV-DCS via la gĂ©nĂ©ration de troisiĂšme harmonique. Les premiers tests de l'expĂ©rience DCS utilisant notre source laser ont Ă©tĂ© rĂ©alisĂ©s sur un Ă©talon Fabry-PĂ©rot (FP) et sur la molĂ©cule O2. Nous avons rĂ©cupĂ©rĂ© avec prĂ©cision lâintervalle spectrale libre du FP et obtenu, avec une grande prĂ©cision, la position des transitions ro-vibrationnelles de l'O2 Ă 760 nm. Nous avons dĂ©montrĂ© que la source laser Ă cavitĂ© unique dĂ©veloppĂ©e ici offre une stabilitĂ© de phase relative suffisamment Ă©levĂ©e (au moins 330 ms) entre les deux Ă©missions laser. Ces premiers rĂ©sultats reprĂ©sentent une Ă©tape importante vers la tĂ©lĂ©dĂ©tection des gaz traces atmosphĂ©riques par UV-DCS. [1] IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. PĂ©an, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press [2] Rieker, G. B., Giorgetta, F. R., Coddington, I., Swann, W. C., Sinclair, L. C., Cromer, C. L., ... & Newbury, N. R. (2013, November). Dual-comb spectroscopy of greenhouse gases over a 2-km outdoor path. In Optical Instrumentation for Energy and Environmental Applications (pp. ET2A-2). Optical Society of America. [3] Coburn, S., Alden, C. B., Wright, R., Cossel, K., Baumann, E., Truong, G. W., ... & Rieker, G. B. (2018). Regional trace-gas source attribution using a field-deployed dual frequency comb spectrometer. Optica, 5(4), 320-327. [4] Galtier, S., Pivard, C., & Rairoux, P. (2020). Towards DCS in the UV Spectral Range for Remote Sensing of Atmospheric Trace Gases. Remote Sensing, 12(20), 3444
Spectroscopie UV à Double Peigne de Fréquence (dual comb) en vue de l'étude de la molécule OH
L'Ă©volution de la phase gazeuse atmosphĂ©rique est une prĂ©occupation majeure pour la qualitĂ© de l'air et l'Ă©volution du climat, comme indiquĂ© dans le rĂ©cent rapport du GIEC [1]. Dans ce contexte, le radical OH a Ă©tĂ© reconnu comme l'une des molĂ©cules clĂ©s de l'atmosphĂšre, participant par exemple Ă 90 % de la rĂ©duction de mĂ©thane atmosphĂ©rique. Les interactions radicalaires OH dans l'atmosphĂšre ne sont pas encore entiĂšrement comprises car elles sont trĂšs difficiles Ă mesurer. Pour amĂ©liorer la comprĂ©hension du rĂŽle de l'OH dans l'atmosphĂšre, il existe un besoin d'instruments qui doivent ĂȘtre sensibles, prĂ©cis et avoir un temps d'acquisition rapide dans la durĂ©e de vie de l'OH (ms). Nous proposons d'Ă©tendre la mĂ©thode de spectroscopie Ă double peigne de frĂ©quence (DCS) dĂ©jĂ existant dans l'IR [2,3] Ă la rĂ©gion proche UV afin de tirer parti de la forte section efficace d'absorption de OH Ă 308 nm. Une Ă©tude numĂ©rique et thĂ©orique [4] a Ă©valuĂ© efficacement la faisabilitĂ© de la mĂ©thode DCS dans le domaine UV. Cette Ă©tude conclut que la source laser Ti:sa Ă verrouillage de mode par effet Kerr semble ĂȘtre la source laser la plus adaptĂ©e pour rĂ©aliser le DCS dans l'UV. Les avantages de la mĂ©thode DCS pour la tĂ©lĂ©dĂ©tection sont multiples : vitesse d'acquisition rapide avec une sensibilitĂ© similaire aux mĂ©thodes spectroscopiques existantes, c'est une mĂ©thode in-situ, sans prĂ©lĂšvement d'Ă©chantillons et indĂ©pendant des fluctuations atmosphĂ©riques. Une source laser DCS a Ă©tĂ© entiĂšrement rĂ©alisĂ©e en laboratoire avec une gĂ©omĂ©trie originale. Il consiste en un laser Ă cavitĂ© en anneau unique gĂ©nĂ©rant deux trains d'impulsions de 100 fs. Cette gĂ©omĂ©trie est avantageuse pour la mĂ©thode DCS car elle permet un partage des bruits commun (amplitude et phase) aux deux impulsions.La puissance totale Ă©mise du laser Ă mode verrouillĂ© atteint 700 mW avec une puissance de pompe de 5,5 W, ce qui fournit suffisamment de puissance pour sonder les molĂ©cules atmosphĂ©riques par UV-DCS via la gĂ©nĂ©ration de troisiĂšme harmonique. Les premiers tests de l'expĂ©rience DCS utilisant notre source laser ont Ă©tĂ© rĂ©alisĂ©s sur un Ă©talon Fabry-PĂ©rot (FP) et sur la molĂ©cule O2. Nous avons rĂ©cupĂ©rĂ© avec prĂ©cision lâintervalle spectrale libre du FP et obtenu, avec une grande prĂ©cision, la position des transitions ro-vibrationnelles de l'O2 Ă 760 nm. Nous avons dĂ©montrĂ© que la source laser Ă cavitĂ© unique dĂ©veloppĂ©e ici offre une stabilitĂ© de phase relative suffisamment Ă©levĂ©e (au moins 330 ms) entre les deux Ă©missions laser. Ces premiers rĂ©sultats reprĂ©sentent une Ă©tape importante vers la tĂ©lĂ©dĂ©tection des gaz traces atmosphĂ©riques par UV-DCS. [1] IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. PĂ©an, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press [2] Rieker, G. B., Giorgetta, F. R., Coddington, I., Swann, W. C., Sinclair, L. C., Cromer, C. L., ... & Newbury, N. R. (2013, November). Dual-comb spectroscopy of greenhouse gases over a 2-km outdoor path. In Optical Instrumentation for Energy and Environmental Applications (pp. ET2A-2). Optical Society of America. [3] Coburn, S., Alden, C. B., Wright, R., Cossel, K., Baumann, E., Truong, G. W., ... & Rieker, G. B. (2018). Regional trace-gas source attribution using a field-deployed dual frequency comb spectrometer. Optica, 5(4), 320-327. [4] Galtier, S., Pivard, C., & Rairoux, P. (2020). Towards DCS in the UV Spectral Range for Remote Sensing of Atmospheric Trace Gases. Remote Sensing, 12(20), 3444.The atmospheric gas phase evolution is of main concern for air quality and climate evolution, as indicated in the recent IPPC Report [1]. In this context, the radical OH has been recognized as one of the key molecule in the atmosphere, participating for instance to 90 % of the atmospheric methane loss. The radical OH interactions in the atmosphere remain not fully understood, as it is very challenging to measure. To improve the understanding of the role of OH in the atmosphere, there is a need for instruments that should be sensitive, accurate, and have a fast acquisition time in the timeframe of the OH lifetime (ms). We propose to extend the already existing dual comb spectroscopy (DCS) methodology instrument from the IR [2,3] to the near UV region to take advantage of the strong absorption cross-section of OH at 308 nm. Numerical and theoretical work [4] effectively assess the feasibility of the DCS method in the UV range. This study concludes that the TiSa Kerr lens mode-locked laser source appears to be the most adapted laser source to realize DCS in the UV. The advantages of the remote sensing DCS method are multiple: it is a fast acquisition rate with similar sensitivity than the existing spectroscopic methods, it is an in-situ method, free of sampling retrieval and free of atmospheric fluctuations. A homemade DCS laser source has been fully realized in the laboratory with an original geometry. It consists in a single ring cavity laser generating two pulses trains of 100 fs. This geometry is advantageous for DCS as it allows a common noise sharing (amplitude and phase). The total mode-locked emitted output power reaches 700 mW with 5.5 W pump power, which would provide enough power to probe atmospheric molecules with UV-DCS via third harmonic generation. The first tests of the DCS experiment using our homemade laser source have been realized on Fabry-Perot (FP) and O2 molecules. We retrieved accurately the free spectral range of the FP and obtained, with high accuracy, the ro-vibrational transitions position of O2 at 760 nm. We demonstrated that the here developed single cavity laser source provides high enough relative phase stability (at least 330 ms) between the two laser emissions. These first results represent an important milestone towards atmospheric trace gases remote sensing using UV-DCS. [1] IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S. L. Connors, C. PĂ©an, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M. I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J. B. R. Matthews, T. K. Maycock, T. Waterfield, O. Yelekçi, R. Yu and B. Zhou (eds.)]. Cambridge University Press. In Press [2] Rieker, G. B., Giorgetta, F. R., Coddington, I., Swann, W. C., Sinclair, L. C., Cromer, C. L., ... & Newbury, N. R. (2013, November). Dual-comb spectroscopy of greenhouse gases over a 2-km outdoor path. In Optical Instrumentation for Energy and Environmental Applications (pp. ET2A-2). Optical Society of America. [3] Coburn, S., Alden, C. B., Wright, R., Cossel, K., Baumann, E., Truong, G. W., ... & Rieker, G. B. (2018). Regional trace-gas source attribution using a field-deployed dual frequency comb spectrometer. Optica, 5(4), 320-327. [4] Galtier, S., Pivard, C., & Rairoux, P. (2020). Towards DCS in the UV Spectral Range for Remote Sensing of Atmospheric Trace Gases. Remote Sensing, 12(20), 3444
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