59 research outputs found
Résultats préliminaires: La nouvelle prédominance du mode partenariat public-privé dans la production de tramways au Canada
Profils génomiques de la transcription génique durant la progression du cycle de division cellulaire d'hépatocytes synchronisés suite à une hépatectomie partielle
La capacité de régénération des foies de mammifÚres est considérable. Suite à une hépatectomie partielle, les hépatocytes entrent de façon synchrone dans un état de prolifération dans lequel ils quittent simultanément la phase G0 pour entrer en phase G1. Nous nous sommes intéressés aux changements épigénétiques et transcriptionnels qui surviennent durant ce processus. Pour ce faire, nous avons généré des données de ChIP-seq pour différents temps suivant cette chirurgie pour :
- la polymérase II (pol II),
- la polymérase III (pol III),
- les marqueurs épigénétiques H3K4me3 et H3K36me3,
- ainsi que le cofacteur de transcription HCF-1.
Ces donnĂ©es nous ont permis de suivre et dâexplorer les modifications dans la transcription et les changements Ă travers le gĂ©nome durant la rĂ©gĂ©nĂ©ration hĂ©patique.
La chromatine a été préparée à partir de huit points dans le temps différents suivant l'hépatectomie partielle (1h, 10h, 20h, 28h, 36h, 44h, 48h et 60h). Les échantillons ont été séquencés avec la technologie dite "paired-end" (chaque fragment donne lieu à deux lectures de 50 ou 100 nucléotides, une pour chaque bout) permettant la localisation précise et la longueur exacte de chaque fragment séquencé sur le génome. En moyenne, 225 millions de séquences ont été obtenues pour chaque échantillon, puis cartographiées sur le génome murin (C57BL6/J, assemblage MGSCv37/mm9, juillet 2007).
De façon consistante avec une synchronisation robuste du cycle de division cellulaire, les patrons de transcription des gĂšnes du cycle cellulaire (par exemple, les cdks et les cyclines) rĂ©vĂšlent un Ă©tat actif ou inactif bien dĂ©fini qui corrĂšle avec l'activitĂ© attendue du gĂšne. Nous avons effectuĂ© une premiĂšre analyse globale de l'occupation par la pol II Ă travers les diffĂ©rents points dans le temps et avons identifiĂ© 9 423 gĂšnes montrant un changement significatif dans la fixation de la polymĂ©rase au promoteur. En groupant les gĂšnes ayant un profil similaire, nous avons remarquĂ© une concordance significative entre le point dans le temps du cycle cellulaire pendant lequel la pol II est prĂ©sente de façon maximale au promoteur des gĂšnes et la fonction qui leur est reliĂ©e. Nous continuons dâexplorer gĂšne par gĂšne, les variations au niveau des marqueurs Ă©pigĂ©nĂ©tiques, en fonction du profil de fixation de la pol II. Aucune analyse nâa cependant encore dĂ©butĂ© en ce qui concerne la pol III et le facteur de transcription HCF-1.
L'analyse continue de la transcription des gÚnes du cycle de division cellulaire durant ce processus de régénération hépatique vous sera présentée
RĂ©flexions sur lâexpĂ©rience de terrain dâun doctorant canadien basĂ© en Suisse menant sa recherche en France et au QuĂ©bec
La nouvelle prédominance du mode partenariat public-privé dans la production de tramways au Canada
Afin de comprendre pourquoi tous les nouveaux projets de tramways en cours de dĂ©veloppement au Canada sont rĂ©alisĂ©s en mode partenariat public-privĂ© (PPP) plutĂŽt que grĂące au mode traditionnel (gestion publique) utilisĂ© par le passĂ©, cette recherche porte sur trois projets de tramways prĂ©sentement en cours de rĂ©alisation (Edmonton, Ottawa et Toronto). Ă lâaide de trois Ă©tudes de cas, nous explorons lâargumentaire entourant chacune des dĂ©cisions menant au choix du mode de gouvernance PPP ainsi que la forme prise par ce PPP. Nous dĂ©montrons que dans tous les cas, il est possible dâobserver les mĂ©canismes du transfert de politique, tant volontaire que coercitif. Nous croyons que le transfert de politique peut donc fournir un Ă©lĂ©ment de rĂ©ponse Ă notre question. De plus, lâargumentaire utilisĂ© par les acteurs locaux pour justifier le choix du mode PPP, bien que semblable sur plusieurs points, comporte tout de mĂȘme une combinaison de justifications unique Ă chacun des cas, ce qui nous laisse croire que le PPP est un instrument de politique polyvalent. Ces constats dĂ©montrent lâintĂ©rĂȘt de prendre en considĂ©ration les transferts de politique au niveau municipal et non seulement les transferts qui prennent place entre les Ătats nationaux. To understand why all new light rail projects under development in Canada are carried out in public-private partnership (P3) rather than through the traditional mode (public administration) that prevailed in the past, this research explores three light rail projects currently underway in Edmonton, Ottawa and Toronto. We study the arguments surrounding each decision leading to the choice of P3 governance. We show that in all cases, it is possible to observe the mechanisms of policy transfer, whether voluntary or coercive. Moreover, the argument used by local actors to justify the choice of P3, although similar in several respects, still forms a unique combination of justifications for each case, which leads us to believe that P3s are a versatile policy instrument. These findings demonstrate the importance of taking into account policy transfer at the municipal level and not only transfers that take place between national states
Bike-sharing: the good, the bad, and the future -an analysis of the public discussion on Twitter-
Due to the dilemma of bike-sharing concerning its benefits and drawbacks, and its unclear future, we focused on a mixed-methods approach to analyze this public discussion through posts or âtweetsâ from the social media channel Twitter. We collected around 12,000 tweets in English around the world related to bike-sharing for a period of about six months. We considered two approaches, including topic clustering and sentiment analysis in tweets including: a) bike-sharing related terms and b) âfutureâ and bike-sharing related terms. Strongly positive tweets promote bike-sharing and its benefits such as being convenient, well-performing, and sustainable. Additionally, there is a tendency to write that public, electric, and dockless are better, together with scooters. In contrast, the complaints on bike-sharing focused on inequity, rentals and safety issues, critique on authorities and laws, and poor performance especially of dockless Asian bike-sharing start-ups with low-quality bikes. Around 50% of the tweets that included the terms âfutureâ and âbikeâsharingâ stated that bike-sharing is going to be part of the future of mobility as an electric dockless version together with other shared modes. The hesitant statements towards bike-sharing being part of the future referred mainly to the systems with poor bikesâ quality. Politicians and stakeholders can use this information to enhance bike-sharing or consider the implementation of certain types of bike-sharing in their cities. To the best of the authorsâ knowledge, this study would be one of the first that analysis the public discussion on social media about a transportation system and its future using a mixed-methods approach. Future studies should aim at identifying and comparing the public opinion of different emerging transportation technologies
To put an end to car dependence - Final report of the scoping review of the literature on the modal shift from the car to alternative modes 2010-2020
This research answers the following question: what are the main modal shift strategies discussed in the literature of the last 10 years? It also undertakes to analyze the impacts of each of the strategies present in the literature. It presents a scoping review of the literature aiming to draw an up-to-date portrait of the abundant literature on modal shift in order to synthesize it and present it in an organized manner and draw conclusions for future research and transport and development policies aimed at reducing automobile dependence and inducing a modal shift from the automobile to alternative modes of transport. We reviewed 2,872 studies published between 2010 and 2020 and retained 108 that we analyzed in detail. More than two thirds of studies report positive results of modal shift from the car towards alternative mobility. This leads us to believe that it is possible to implement public policies to facilitate modal shift and thus help reduce car dependence. A large majority of research on public transport reports positive examples. However, for studies on active transportation, we note that almost all of the research (92%) reports successes. By paying attention to the degree of coercion of the interventions investigated in the literature, we see that the âcarrotâ measures which seek to induce the modal shift by offering a benefit are more successful than the âstickâ type measures which aim to restrict certain choices (pricing, tolls, reduction of parking spaces). However, research on the âcarrot and stickâ combination approach reports the most positive results. This leads us to conclude that research on this type of intervention should continue to be developed, even encouraged, and to suggest that public decision-makers take into account the beneficial effects for modal shift resulting from the combination of the two types of interventions simultaneously âcarrot and stickâ
Pour en finir avec la dĂ©pendance automobile : rapport final de lâĂ©tude de la portĂ©e de la littĂ©rature sur le transfert modal de la voiture aux modes alternatifs 2010-2020
Cette recherche répond à la question suivante : quelles sont les principales stratégies de transfert
modal discutĂ©es dans la littĂ©rature des 10 derniĂšres annĂ©es. Elle entreprend aussi dâanalyser les
impacts de chacune des stratégies présentes dans littérature. Elle présente une étude de la portée
de la littĂ©rature visant Ă dresser un portrait Ă jour de lâabondante littĂ©rature sur le transfert modal
afin de la synthĂ©tiser et de la prĂ©senter de façon organisĂ©e et dâen tirer des constats pour la
recherche future et les politiques de transport et dâamĂ©nagement visant Ă rĂ©duire la dĂ©pendance
automobile et Ă induire un transfert modal de lâautomobile vers les modes de transports
alternatifs. Nous avons révisé 2872 études publiées entre 2010-2020 et en avons retenu 108 que
nous avons analysées en détail.
Plus de deux tiers des études rapportent des résultats positifs de transfert modal de la voiture au
profit des mobilitĂ©s alternatives. Ce qui nous porte Ă croire quâil est possible de mettre en place
des politiques publiques afin de faciliter le transfert modal et dâainsi contribuer Ă rĂ©duire la
dĂ©pendance Ă lâautomobile. Parmi les recherches portant sur les transports en commun, une
grande majorité rapporte des exemples positifs. Cependant, du cÎté des études portant sur le
transport actif, nous notons que la presque totalité des recherches (92 %) rapporte des succÚs. En
portant attention au degrĂ© de coercition des interventions enquĂȘtĂ©es dans la littĂ©rature, on
constate que les mesures « carotte » qui cherchent à induire le transfert modal en offrant un
bénéfice ont plus de succÚs que les mesures de type « bùton » qui visent à restreindre certains
choix (tarification, péage, diminution des espaces de stationnement). Cependant, les recherches
portant sur la combinaison « carotte et bùton » rapportent les résultats les plus positifs. Ceci nous
amĂšne Ă conclure que la recherche sur ce type dâintervention devrait continuer Ă ĂȘtre dĂ©veloppĂ©e,
voire encouragée, et à suggérer aux décideurs publics de tenir compte des effets bénéfiques pour
le transfert modal provenant de la combinaison des deux types dâinterventions simultanĂ©ment
« carotte et bùton »
When walking peters out: investigating distance-decay and time-decay for daily walking
In Switzerland, walking accounts for 30% of trips and 44% of single-mode episodes. This is higher than in many countries but does not account for walking distances or durations, which tend to be short according to evidence from North America. This contribution investigates distances and times at which walking peters out, comparing Switzerland, Canada and the USA. We used the 2010 Swiss mobility and transport micro-census, a country-wide representative sample of 62'868 residents who underwent a telephone and computer-assisted interview relating to their mobility behaviour on a single day. We extracted single-mode walking episodes, excluding those starting and terminating at home. Results: in Switzerland, among the 66'090 identified single-mode walking episodes, 45% were leisure-related. Mean and median values differed considerably due to negative exponential distributions. Mean values were around 550-930 metres for most types of destination; only leisure-related walks were significantly longer, at 1.8 km (overall average: 1.3 km). Mean walking time was 20 minutes, strongly influenced by leisure-related walking whose duration (33 minutes) was 2-3 times higher than for other motives. Mean walks to work took six-and-a-half minutes, over 581 metres; shopping-related walks averaged 9 minutes for 613 metres. In Halifax, a county-sized municipality in Canada, Millward et al. (2013) found mean values for single-episode walking of 9 minutes for 670 metres. The 25th, 50th (median) and 75th percentiles were 3, 6 and 12 minutes, for respectively 230, 480 and 860 metres. Corresponding values in Switzerland were 5, 10 and 20 minutes, for 300, 600 and 1500 metres, respectively. Investigation of USA-wide travel survey results (Yang and Diez-Roux, 2012) yielded mean and median walking distances (all purposes combined) of respectively 1.13 km and 800 m, with mean and median durations of around 15 and 10 minutes, respectively. However, the USA data included walks originating and finishing at home, which tend to be longer. Conclusions: in all three countries, half of all walking trips are under the 500-800 metre mark and last less than 6-10 minutes. Policy implications: up to now, the global walking-promotion agenda has concentrated on increasing mode shares; this research suggests that emphasis should be put on increasing walking times and distances, especially for non-leisure destinations. Municipalities require the support of other policy levels to answer this challenge
Cycles of gene expression and genome response during mammalian tissue regeneration.
Compensatory liver hyperplasia-or regeneration-induced by two-thirds partial hepatectomy (PH) permits the study of synchronized activation of mammalian gene expression, particularly in relation to cell proliferation. Here, we measured genomic transcriptional responses and mRNA accumulation changes after PH and sham surgeries.
During the first 10-20Â h, the PH- and sham-surgery responses were very similar, including parallel early activation of cell-division-cycle genes. After 20Â h, however, whereas post-PH livers continued with a robust and coordinate cell-division-cycle gene-expression response before returning to the resting state by 1Â week, sham-surgery livers returned directly to a resting gene-expression state. Localization of RNA polymerase II (Pol II), and trimethylated histone H3 lysine 4 (H3K4me3) and 36 (H3K36me3) on genes dormant in the resting liver and activated during the PH response revealed a general de novo promoter Pol II recruitment and H3K4me3 increase during the early 10-20Â h phase followed by Pol II elongation and H3K36me3 accumulation in gene bodies during the later proliferation phase. H3K36me3, generally appearing at the first internal exon, was preceded 5' by H3K36me2; 3' of the first internal exon, in about half of genes H3K36me3 predominated and in the other half H3K36me2 and H3K36me3 co-existed. Further, we observed some unusual gene profiles with abundant Pol II but little evident H3K4me3 or H3K36me3 modification, indicating that these modifications are neither universal nor essential partners to Pol II transcription.
PH and sham surgical procedures on mice reveal striking early post-operatory gene expression similarities followed by synchronized mRNA accumulation and epigenetic histone mark changes specific to PH
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