On List Coloring with Separation of the Complete Graph and Set System Intersections

We consider the following list coloring with separation problem: Given a graph $G$ and integers $a,b$, find the largest integer $c$ such that for any list assignment $L$ of $G$ with $|L(v)|= a$ for any vertex $v$ and $|L(u)\cap L(v)|\le c$ for any edge $uv$ of $G$, there exists an assignment $\varphi$ of sets of integers to the vertices of $G$ such that $\varphi(u)\subset L(u)$ and $|\varphi(v)|=b$ for any vertex $u$ and $\varphi(u)\cap \varphi(v)=\emptyset$ for any edge $uv$. Such a value of $c$ is called the separation number of $(G,a,b)$. Using a special partition of a set of lists for which we obtain an improved version of Poincar\'e's crible, we determine the separation number of the complete graph $K_n$ for some values of $a,b$ and $n$, and prove bounds for the remaining values.Comment: 18 page

The Genetics of Vitamin C Loss in Vertebrates

Vitamin C (ascorbic acid) plays important roles as an anti-oxidant and in collagen synthesis. These important roles, and the relatively large amounts of vitamin C required daily, likely explain why most vertebrate species are able to synthesize this compound. Surprisingly, many species, such as teleost fishes, anthropoid primates, guinea pigs, as well as some bat and Passeriformes bird species, have lost the capacity to synthesize it. Here, we review the genetic bases behind the repeated losses in the ability to synthesize vitamin C as well as their implications. In all cases so far studied, the inability to synthesize vitamin C is due to mutations in the L-gulono-γ-lactone oxidase (GLO) gene which codes for the enzyme responsible for catalyzing the last step of vitamin C biosynthesis. The bias for mutations in this particular gene is likely due to the fact that losing it only affects vitamin C production. Whereas the GLO gene mutations in fish, anthropoid primates and guinea pigs are irreversible, some of the GLO pseudogenes found in bat species have been shown to be reactivated during evolution. The same phenomenon is thought to have occurred in some Passeriformes bird species. Interestingly, these GLO gene losses and reactivations are unrelated to the diet of the species involved. This suggests that losing the ability to make vitamin C is a neutral trait

On List Coloring With Separation Of The Complete Graph And Set System Intersections

International audienceWe consider the following list coloring with separation problem: Given a graph $G$ and integers $a,b$, find the largest integer $c$ such that for any list assignment $L$ of $G$ with $|L(v)|= a$ for any vertex $v$ and $|L(u)\cap L(v)|\le c$ for any edge $uv$ of $G$, there exists an assignment $\varphi$ of sets of integers to the vertices of $G$ such that $\varphi(u)\subset L(u)$ and $|\varphi(v)|=b$ for any vertex $u$ and $\varphi(u)\cap \varphi(v)=\emptyset$ for any edge $uv$. Such a value of $c$ is called the separation number of $(G,a,b)$. Using a special partition of a set of lists for which we obtain an improved version of Poincaré's crible, we determine the separation number of the complete graph $K_n$ for some values of $a,b$ and $n$, and prove bounds for the remaining values

Passively mode-locked diode-pumped Tm,Ho:LiYF4 laser

International audienceWe report on the first demonstration of a diode-pumped passively mode-locked Tm,Ho:LiYF4 laser. Stable continuous-wave mode-locking is achieved by employing a single-layer graphene as a saturable absorber (SA). For a reflection-type graphene-SA, the laser delivers 5.2 ps pulses at ~2051 nm with an average output power of 40 mW at a repetition rate of 89.86 MHz. With a transmission-type graphene-SA and smaller output coupling, the output power is scaled up to 80 mW while the laser operated in a double-pulse regime

(Tm,Ho):YLF laser passively mode-locked with a graphene saturable absorber

International audienc

STRAPOLETE : Studying summer polar stratosphere.

International audienceThe polar stratosphere in the summertime remains largely unexplored. Dynamical conditions are characterizedby large scale transport and mixing between air masses of higher and lower latitude origins. Understanding theseexchanges is crucial since they have a large impact on the distribution of trace gases and aerosols at polar latitudes,and thus on the stratospheric ozone budget. Ozone change affects the radiative balance, the coupling betweentroposphere and stratosphere, and therefore the climate.In the framework of the International Polar Year, the STRAPOLETE project starts on January 2009. It is associatedwith a successful balloon borne campaign which took place close to Kiruna (Sweeden) from 2 August 2009 to12 September 2009 with eight balloon flights. During this campaign the main characteristics of the summertimearctic stratosphere have been captured. The data set obtained using UV-visible and infrared instruments, remoteand in situ sensing embarked spectrometers provided detailed information on vertical distributions of more thanfifteen chemical tracers and reactive species from the upper troposphere to the middle stratosphere. A number of insitu optical aerosol counters, a UV-visible remote spectrometer for the aerosol extinction and a photopolarimeterprovided information on the nature and size distribution of the stratospheric aerosols. These balloon measurementswith high precision and high vertical resolution are relevant to qualify the dynamical processes occurring in thisregion during summertime, the aerosols variability, the bromine abundance and establish a reference state of thepolar summer stratosphere. The data set is completed by satellite data offering large spatial coverage of the regionof interest. Data analysis is made using relevant dynamical (trajectory calculations, contour advection model) andchemistry-transport models (CTM) to highlight major mechanisms that control the distribution of tracers, aerosolsand bromine.An overview of the project, its scientific issues, the measurement campaign and some balloon measurementsobtained will be presented, as well as preliminary comparisons between measurements and models outputs

An overview of the StraPolEté project : dynamics, aerosols and bromine content of the polar region in summertime

International audienceThe polar stratosphere in the summertime remains largely unexplored. Dynamical conditions are characterized by large scale transport and mixing between air masses of higher and lower latitude origins. Understanding these exchanges is crucial since they have a large impact on the distribution of trace gases and aerosols at polar latitudes, and thus on the stratospheric ozone budget. Ozone change affects the radiative balance, the coupling between troposphere and stratosphere, and therefore the climate. In the framework of the International Polar Year, the STRAPOLETE project starts on January 2009. It is associated with a successful balloon borne campaign which took place close to Kiruna (Sweeden) from 2 August 2009 to 12 September 2009 with eight balloon flights. During this campaign the main characteristics of the summertime arctic stratosphere have been captured. The data set obtained using UV-visible and infrared instruments, remote and in situ sensing embarked spectrometers will provide detailed information on vertical distributions of more than fifteen chemical tracers and reactive species from the upper troposphere to the middle stratosphere. A number of in situ optical aerosol counters, a UV-visible remote spectrometer for the aerosol extinction and a photopolarimeter will provide information on the nature and size distribution of the stratospheric aerosols. These balloon measurements with high precision and high vertical resolution are relevant to qualify the dynamical processes occuring in this region during summertime, the aerosols variability, the bromine abundance and establish a reference state of the polar summer stratosphere. The data set is "complete" by satellite data offering large spatial coverage of the region of interest. Data analysis is made using relevant dynamical (trajectory calculations, contour advection model) and chemistry-transport models (CTM) to highlight major mechanisms that controlled the distribution of tracers, aerosols and bromine. An overview of the project, its scientific issues, the measurements obtained will be presented, as well as preliminary results and comparisons between measurements and models outputs

An overview of the StraPolEté project : dynamics, aerosols and bromine content of the polar region in summertime

International audienceThe polar stratosphere in the summertime remains largely unexplored. Dynamical conditions are characterized by large scale transport and mixing between air masses of higher and lower latitude origins. Understanding these exchanges is crucial since they have a large impact on the distribution of trace gases and aerosols at polar latitudes, and thus on the stratospheric ozone budget. Ozone change affects the radiative balance, the coupling between troposphere and stratosphere, and therefore the climate. In the framework of the International Polar Year, the STRAPOLETE project starts on January 2009. It is associated with a successful balloon borne campaign which took place close to Kiruna (Sweeden) from 2 August 2009 to 12 September 2009 with eight balloon flights. During this campaign the main characteristics of the summertime arctic stratosphere have been captured. The data set obtained using UV-visible and infrared instruments, remote and in situ sensing embarked spectrometers will provide detailed information on vertical distributions of more than fifteen chemical tracers and reactive species from the upper troposphere to the middle stratosphere. A number of in situ optical aerosol counters, a UV-visible remote spectrometer for the aerosol extinction and a photopolarimeter will provide information on the nature and size distribution of the stratospheric aerosols. These balloon measurements with high precision and high vertical resolution are relevant to qualify the dynamical processes occuring in this region during summertime, the aerosols variability, the bromine abundance and establish a reference state of the polar summer stratosphere. The data set is "complete" by satellite data offering large spatial coverage of the region of interest. Data analysis is made using relevant dynamical (trajectory calculations, contour advection model) and chemistry-transport models (CTM) to highlight major mechanisms that controlled the distribution of tracers, aerosols and bromine. An overview of the project, its scientific issues, the measurements obtained will be presented, as well as preliminary results and comparisons between measurements and models outputs

Recommendations of the treatment-resistant depression expert center network for promoting tobacco smoking cessation based on the results from the real-world FACE-TRD national cohort

International audienceTobacco smoking has been associated with suicide, impulsivity and depression in non-clinical populations with differences across sexes

Antibiotiques et résistance bactérienne : pistes d'actions pour ancrer les progrès de 2020

International audienceL'année 2020 a bouleversé les comportements du quotidien, en raison de la pandémie de COVID-19 et des confinements et gestes barrières à adopter pour limiter sa propagation. Ces modifications ont contribué à limiter la transmission des autres infections ; elles ont aussi impacté le recours aux soins et la prise en charge de certaines pathologies en santé humaine