Domino Snake Problems on Groups

In this article we study domino snake problems on finitely generated groups. We provide general properties of these problems and introduce new tools for their study. The first is the use of symbolic dynamics to understand the set of all possible snakes. Using this approach we solve many variations of the infinite snake problem including the geodesic snake problem for certain classes of groups. Next, we introduce a notion of embedding that allows us to reduce the decidability of snake problems from one group to another. This notion enable us to establish the undecidability of the infinite snake and ouroboros problems on nilpotent groups for any generating set, given that we add a well-chosen element. Finally, we make use of monadic second order logic to prove that domino snake problems are decidable on virtually free groups for all generating sets.Comment: Accepted to FCT 2023. Comments welcome

Introduction of SARS in France, March–April, 2003

We describe severe acute respiratory syndrome (SARS) in France. Patients meeting the World Health Organization definition of a suspected case underwent a clinical, radiologic, and biologic assessment at the closest university-affiliated infectious disease ward. Suspected cases were immediately reported to the Institut de Veille Sanitaire. Probable case-patients were isolated, their contacts quarantined at home, and were followed for 10 days after exposure. Five probable cases occurred from March through April 2003; four were confirmed as SARS coronavirus by reverse transcription–polymerase chain reaction, serologic testing, or both. The index case-patient (patient A), who had worked in the French hospital of Hanoi, Vietnam, was the most probable source of transmission for the three other confirmed cases; two had been exposed to patient A while on the Hanoi-Paris flight of March 22–23. Timely detection, isolation of probable cases, and quarantine of their contacts appear to have been effective in preventing the secondary spread of SARS in France

The RNAi machinery controls distinct responses to environmental signals in the basal fungus Mucor circinelloides

BACKGROUND: RNA interference (RNAi) is a conserved mechanism of genome defence that can also have a role in the regulation of endogenous functions through endogenous small RNAs (esRNAs). In fungi, knowledge of the functions regulated by esRNAs has been hampered by lack of clear phenotypes in most mutants affected in the RNAi machinery. Mutants of Mucor circinelloides affected in RNAi genes show defects in physiological and developmental processes, thus making Mucor an outstanding fungal model for studying endogenous functions regulated by RNAi. Some classes of Mucor esRNAs map to exons (ex-siRNAs) and regulate expression of the genes from which they derive. To have a broad picture of genes regulated by the silencing machinery during vegetative growth, we have sequenced and compared the mRNA profiles of mutants in the main RNAi genes by using RNA-seq. In addition, we have achieved a more complete phenotypic characterization of silencing mutants.  RESULTS: Deletion of any main RNAi gene provoked a deep impact in mRNA accumulation at exponential and stationary growth. Genes showing increased mRNA levels, as expected for direct ex-siRNAs targets, but also genes with decreased expression were detected, suggesting that, most probably, the initial ex-siRNA targets regulate the expression of other genes, which can be up- or down-regulated. Expression of 50% of the genes was dependent on more than one RNAi gene in agreement with the existence of several classes of ex-siRNAs produced by different combinations of RNAi proteins. These combinations of proteins have also been involved in the regulation of different cellular processes. Besides genes regulated by the canonical RNAi pathway, this analysis identified processes, such as growth at low pH and sexual interaction that are regulated by a dicer-independent non-canonical RNAi pathway.  CONCLUSION: This work shows that the RNAi pathways play a relevant role in the regulation of a significant number of endogenous genes in M. circinelloides during exponential and stationary growth phases and opens up an important avenue for in-depth study of genes involved in the regulation of physiological and developmental processes in this fungal model

Domino Snake Problems on Groups

International audienc

Unusual presentation of bladder cancer resurgence and efficacy of radiotherapy.

A 68-year-old man with a history of bladder cancer presented with perineal pain and penile priapism. The work up showed multiple lesions strictly located in the penis; biopsy confirmed metastases of bladder cancer. Surgery was judged unfeasible and chemotherapy failed to improve symptoms. Radiotherapy was therefore delivered on the whole penis and resulted in a rapid clinical benefit and persistent control of the disease. Penile metastases are very rare and no consensus exists concerning their management; radiotherapy appears as a promising therapeutic option not only to palliate pain but also to control the disease

Physical exercise in the treatment of depression: Should we care?

It is well established that physical activity and exercise positively affect physical and mental health. While the application of this knowledge was generalized less than 5 years ago, current research aims to demonstrate the effectiveness of this approach on specific fields of psychiatry. Although some progress must still be made on the methodological level, recent studies show the great impact of physical exercise prescription with regard to the management of different psychiatric disorders (major depression, anxiety disorders, alcoholism, bipolar disorder, fibromyalgia, and schizophrenia). This paper aims to identify an alternative to conventional treatment of depression and to develop specific exercise programs for depressive disorders

Evaluation of an optical scintillating fiber detector for CT dosimetry

International audiencePurpose: The aim of this work is to compare the energy response of a scintillating fiber to that of standarddetectors used for dose monitoring in Computed Tomography (CT) and confirm the validity of PlasticScintillating Detectors in CT dosimetry. We also seek to model the scintillating fiber response in realistic irradiation conditions for future applications on a complete dose measurement system. For this, we have modeled anX-ray generator emission and validated the model using its measured X-rays spectrum.Materials and methods: Irradiations were performed in an X-ray generator at voltage varying from 80 to 140 kV.The Plastic Scintillating Detector (PSD) was compared with a pencil ion chamber and Thermo-LuminescentDetectors (TLD).Monte Carlo simulations of each detector response were compared to measurements in order to validate thesimulation in a simple case.Results: The Monte Carlo simulations reproduced accurately the response of each detector with less than 3% and5% of difference for the ion chamber and the TLDs respectively. When comparing the PSD with the two standarddetectors, we observed that while the plastic scintillator detector and the ion chamber responses presented lessthan 5% discrepancy, they both were very different than TLDs response on the whole investigated energy range.The Monte Carlo simulation of the PSD reproduced accurately the response of the plastic scintillating detectorwith less than 3% of difference.Conclusion: The X-ray spectrum has been accurately measured which allowed to successfully reproduce theenergy response of the PSD using Monte Carlo simulations. Although this study proved that the scintillatingfibers energy response is appropriate for CT dose measurement, further experiments must be performed inclinical conditions

Conception of a New Recoil Proton Telescope for Real-Time Neutron Spectrometry in Proton-Therapy

International audienceNeutrons are the main type of secondary particles emitted in proton-therapy. Because of the risk of secondary cancer and other late occurring effects, the neutron dose should be included in the out-of-field dose calculations. A neutron spectrometer has to be used to take into account the energy dependence of the neutron radiological weighting factor. Due to its high dependence on various parameters of the irradiation (beam, accelerator, patient), the neutron spectrum should be measured independently for each treatment. The current reference method for the measurement of the neutron energy, the Bonner Sphere System, consists of several homogeneous polyethylene spheres with increasing diameters equipped with a proportional counter. It provides a highresolution reconstruction of the neutron spectrum but requires a time-consuming work of signal deconvolution. New neutron spectrometers are being developed, but the main experimental limitation remains the high neutron flux in proton therapy treatment rooms. A new model of a real-time neutron spectrometer, based on a Recoil Proton Telescope technology, has been developed at the IPHC. It enables a real-time high-rate reconstruction of the neutron spectrum from the measurement of the recoil proton trajectory and energy. A new fast-readout microelectronic integrated sensor, called FastPixN, has been developed for this specific purpose. A first prototype, able to detect neutrons between 5 and 20 MeV, has already been validated for metrology with the AMANDE facility at Cadarache. The geometry of the new Recoil Proton Telescope has been optimized via extensive Geant4 Monte Carlo simulations. Uncertainty sources have been carefully studied in order to improve simultaneously efficiency and energy resolution, and solutions have been found to suppress the various expected backgrounds. We are currently upgrading the prototype for secondary neutron detection in proton therapy applications