Phénologie de l'épinette noire dans le haut boréal : un patron de la croissance intra-annuelle primaire et secondaire en relation avec la température de l'air journalière

Par définition, la phénologie végétale est l'étude de l'apparition d'événements annuels, cycliques et périodiques dans la croissance déterminée par les variations saisonnières du climat (exemple: débourrement des bourgeons, fructification, etc.). La phénologie constitue par le fait même un outil important dans l'étude des changements climatiques. Mieux comprendre comment la température de l'air influence directement le développement de l'arbre au jour le jour et durant une saison de croissance peut nous aider à anticiper les impacts des changements climatiques. Cette étude tente d'approfondir les connaissances actuelles restreintes sur la relation entre la température de l'air et la phénologie de l'épinette noire. L'objectif principal de la recherche est d'obtenir un patron de la phénologie de croissance intra-annuelle en relation avec les températures de l'air. Cette recherche se déroule près de la localité de Radisson dans la municipalité de la Baie James (53° 42' 24"N, 77° 45' 03" W). Ce site a été choisi en raison de la présence d'un dispositif expérimental qui offre la possibilité d'isoler les différents facteurs qui influencent la croissance de l'épinette noire (Picea mariana Mill. BSP). Il s'agit d'un site du réseau Sila (climat en inuktitut) installé par le Centre d'études nordiques (Université Laval, UQAR et INRS). Le réseau Sila est un réseau de télémétrie environnemental qui a été construit pour alimenter des recherches en données sur l'environnement. Il comprend 75 stations automatisées réparties sur 4500 km de latitude entre la vallée du St-Laurent près de Québec jusqu'à l'île Ward Hunt à l'extrémité septentrionale du Canada. Le site SILA de Radisson comprend quatre stations voisines; trois stations sont situées en tourbière et présentent des températures plus froides que la quatrième qui est en milieu sec de type pessière à lichen (différence de 1 à 2 C°). La croissance de l'épinette noire sera étudiée en deux volets:\ud • La croissance primaire soit le débourrement des bourgeons et l'élongation des tiges; La croissance secondaire soit la croissance radiale. Chaque étape de la phénologie est d'abord étudiée séparément puis mise en relation entre elles. Par la suite, la phénologie sera comparée entre les sites Sila. Les résultats montrent que la phénologie est reliée à la température de l'air. Les températures plus chaudes du site 4 par rapport aux autres sites ont entraîné un débourrement précoce, une élongation plus grande et une croissance radiale plus forte et plus longue. Pour tous les sites, lors de journées pluvieuses la croissance radiale est favorisée et la croissance des branches est ralentie. Le contraire s'applique lors de journées chaudes et ensoleillées. Pour l'élongation des tiges, le taux de croissance des arbres entre les sites ne présente pas de différence significative. Cependant, la température à laquelle le taux de croissance maximum est atteint est plus élevée sur le site 4 que sur les autres sites. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Croissance intra annuelle, Débourrement, Croissance radiale, Températures journalières, Changements climatiques

Odeurs et parfums romanesques de la seconde moitié du XIXe siècle (Zola, Huysmans)

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal

Promoting fruit and vegetable intake in childbearing age women at risk for gestational diabetes mellitus : a randomised controlled trial

This randomised controlled trial verified the efficacy of an implementation intentions intervention (n=24) to promote fruit and vegetable consumption among childbearing age women at risk for gestational diabetes mellitus against a control condition based on the question-behaviour effect (n=26). There was only a significant time effect (F(2,85)=5.69, p=0.0048). Both groups increased their vegetable consumption compared to baseline at 3 months (p=0.0022) and 6 months (p=0.0042). There were no significant effects on weight, waist circumference and blood glucose levels. Implementation intentions and the question-behaviour effect appear to be effective behaviour change techniques to promote vegetable intake among this high-risk population

Influence des capacités de régulation du bébé et des représentations maternelles sur le traitement de l'information visuelle du nourrisson au quatrième mois de vie

Cette étude examine l'influence de facteurs endogènes et exogènes sur les performances cognitives de nourrissons de quatre mois. La régulation du bébé (sommeil, pleurs par jour, alimentation) est mesurée par le Questionnaire d'alimentation de Ramsav (Ramsay et al., 2001). Les représentations maternelles sont évaluées par le Working Model of the Child Interview (Zeanah et al., 1994). La procédure d'habituation visuelle est retenue comme mesure du traitement de l'information visuelle. Trente-trois dyades mère-nourrisson (20 garçons et 13 filles) participent à cette recherche qui compte deux collectes de données permettant d'estimer la stabilité des mesures cognitives. Les résultats suggèrent que tant les capacités de régulation du nourrisson, que les représentations maternelles et le degré de dysphorie dépressive post-natale peuvent être associés aux différences individuelles en habituation visuelle, certaines variables d'habituation étant mieux expliquées par l'addition de ces deux facteurs d'influence. Quelques avenues de recherche visant une étude plus approfondie des influences réciproques de la dyade mère-bébé sur le développement cognitif du nourrisson sont proposées

Validity and reliability of a brief selfreported questionnaire assessing fruit and vegetable consumption among pregnant women

Background: Short instruments measuring frequency of specific foods, such as fruit and vegetable (FV), are increasingly used in interventions. The objective of the study was to verify the validity and test-retest reliability of such an instrument among pregnant women. Methods: Pregnant women from the region of Quebec City, Quebec, Canada, were recruited through e-mails sent to female students and employees of the local university from October 2014 to April 2015. To assess the validity of the fruit and vegetable questionnaire (FVQ) developed by Godin et al. (Can J Public Health 99: 494-498, 2008), pregnant women were asked in a first mailing to complete the FVQ assessing FV intake over the past 7 days and a 3-day estimated food record. A subsample (n¿=¿33) also gave a fasting blood sample and completed a validated semi-quantitative FFQ administered by a trained registered dietitian during a visit at the research center. FV intakes for all instruments were calculated in terms of servings of FV based on Canada’s Food Guide definition of a serving of fruit or vegetable. In order to assess its test-retest reliability, respondents were asked to complete the FVQ 14 days later in a second mailing. Results: Forty-eight pregnant women from all three trimesters completed the questionnaires in the first mailing. FV intake assessed using the FVQ was correlated to FV consumption measured using the food record (r¿=¿0.34, p¿=¿0.0180) and the FFQ (r¿=¿0.61, p¿=¿0.0002). Results were similar when controlling for energy intake and the experience of nausea in the past month. Only ß-cryptoxanthin was significantly correlated to FV intake assessed by the FFQ when adjusted for the presence of nausea (r¿=¿0.35, p¿=¿0.0471). Data on the test-retest reliability was available for 44 women and the intra-class coefficient for the FVQ was 0.72 at a mean 28-day interval. Conclusions: The FVQ has acceptable validity and test-retest reliability values, but seems to underestimate FV servings in pregnant women. It represents an interesting alternative for researchers or clinicians interested in estimating quickly FV intake among pregnant women, such as in large trials or during prenatal visits. The FVQ should however be coupled with other self-reported measures, such as a food record, for assessing precise individual FV intake

Validation of a newly automated web-based 24-hour dietary recall using fully controlled feeding studies

BACKGROUND: Assessment of food intake is a cornerstone of nutritional research. However, the use of minimally validated dietary assessment methods is common and can generate misleading results. Thus, there is a need for valid, precise and cost-effective dietary assessment tools to be used in large cohort studies. The objective is to validate a newly developed automated self-administered web-based 24-h dietary recall (R24W), within a population of adults taking part in fully controlled feeding studies. METHODS: Sixty two adults completed the R24W twice while being fed by our research team. Actual intakes were precisely known, thereby allowing the analysis of the proportion of adequately self-reported items. Association between offered and reported portion sizes was assessed with correlation coefficients and agreement with the kappa score while systematics biases were illustrated with Bland-Altman Plot. RESULTS: Participants received an average of 16 food items per testing day. They reported 89.3% of the items they received. The more frequently omitted food categories were vegetables included in recipes (40.0%) as well as side vegetables (20.0%) and represented less than 5% of the actual daily energy intake. Offered and self-reported portion sizes were significantly correlated (r = 0.80 P < 0.001) and demonstrated a strong agreement as assessed by the kappa score of 0.62. Reported portion sizes for individual food items were on average 3.2 g over the offered portion sizes. Portions of 100 g and above were on average underestimated by 2.4% (r = 0.68 P < 0.01; kappa score = 0.50) while small portions (less than 100 g) were overestimated by 17.1% (r = 0.46 P < 0.01; kappa score = 0.43). A nonsignificant underestimation (−13.9 kcal ± 646.3 kcal; P = 0.83) of energy intake was noted. CONCLUSION: R24W performed well as participants were able to report the great majority of items they ate and selected portion size strongly related to the one they received. This suggests that food items are easily to find within the R24W and images of portion sizes used in this dietary assessment tool are adequate and can provide valid food intake evaluation

Effects of a dietary intervention promoting the adoption of a Mediterranean food pattern on fast-food consumption among healthy French-Canadian women

It is expected that a dietary intervention based on the traditional Mediterranean food pattern should be associated with a reduction in fast-food consumption but this has never been tested before. We assessed the impact of a 12-week dietary intervention, promoting the adoption of a Mediterranean food pattern, on fast-food consumption among seventy-one healthy women aged between 30 and 65 years. The dietary intervention consisted of two group sessions and seven individual sessions with a dietitian. To determine the Mediterranean dietary score (MedScore) and fast-food consumption, an FFQ was administered. During the 12-week intervention, the MedScore significantly increased (from 21·1 (SD 3·6) units at baseline to 28·6 (SD 4·4) units at week 12, P,0·0001), while the fast-food consumption significantly decreased (from 51·7 (SD 46·4) g/d at baseline to 20·5 (SD 18·2) g/d at week 12, P,0·0001). Moreover, women who had a higher consumption of fast food at baseline decreased their fast-food consumption to the most (r 20·50, P,0·0001). When four subgroups were formed on the basis of median values of Medscore and fast-food consumption changes, it was found that only the subgroup of women which increased the most their MedScore and decreased the most their fast-food consumption experienced a significant decrease in BMI (P,0·01). In conclusion, a dietary intervention promoting the Mediterranean food pattern led to a decrease in fast-food consumption among healthy women even if it was not a specific target of the intervention. Dietary strategies for increasing intake of healthy foods may be a useful approach for decreasing intake of less healthy foods

Development and validation of the perceived food environment questionnaire in a french-canadian population

Objective: The present study aimed to develop and validate a questionnaire assessing perceived food environment in a French-Canadian population. Design: A questionnaire, the Perceived Food Environment Questionnaire, was developed assessing perceived accessibility to healthy (nine items) and unhealthy foods (three items). A pre-test sample was recruited for a pilot testing of the questionnaire. For the validation study, another sample was recruited and completed the questionnaire twice. Exploratory factor analysis was performed on the items to assess the number of factors (subscales). Cronbach’s a was used to measure internal consistency reliability. Test–retest reliability was assessed with Pearson correlations. Setting: Online survey. Results: Men and women from the Québec City area (n 31 in the pre-test sample; n 150 in the validation study sample). The pilot testing did not lead to any change in the questionnaire. The exploratory factor analysis revealed a two-subscale structure. The first subscale is composed of six items assessing accessibility to healthy foods and the second includes three items related to accessibility to unhealthy foods. Three items were removed from the questionnaire due to low loading on the two subscales. The subscales demonstrated adequate internal consistency (Cronbach’s a=0·77 for healthy foods and 0·62 for unhealthy foods) and test–retest reliability (r=0·59 and 0·60, respectively; both P<0·0001). Conclusions: The Perceived Food Environment Questionnaire was developed for a French-Canadian population and demonstrated good psychometric properties. Further validation is recommended if the questionnaire is to be used in other populations

The lipoprotein/lipid profile is modulated by a gene–diet interaction effect between polymorphisms in the liver X receptor-α and dietary cholesterol intake in French-Canadians

Genetic and nutritional factors interact together and modulate the plasma lipid profile. We identified variations in the gene encoding the liver X receptor α (LXRα) and investigated their effects on the plasma lipoprotein/lipid profile. We also examined whether the association between cholesterol intake and plasma lipid profile was modulated by LXRα variants. The LXRα gene was sequenced in thirty-five French-Canadian men with high plasma total cholesterol (>5·0 mmol/l) and LDL-cholesterol (>3·5 mmol/l) concentrations. Dietary cholesterol was obtained from a food-frequency questionnaire. The LXRα c.-115G>A, c.-840C>A and c.-1830T>C genotypes were determined by direct sequencing in 732 subjects. Molecular screening of the LXRα gene revealed sixteen variants. Genotypes c.-115G>A, c.-840C>A and c.-1830T>C (rare allele frequency of 14·3 %, 14·2 % and 11·0 %, respectively) were analysed further. Plasma total cholesterol concentrations were higher in carriers of the -115A, -840A and -1830C allele, compared with the -115G/G, -840C/C and -1830T/T homozygotes (P ≤ 0·05). In a model including the c.-115G>A polymorphism, cholesterol intake, the interaction term c.-115G>A × cholesterol intake (mg/d) and covariates, LXRα-115G>A explained 1·8 % and 2·1 % of the variance in total cholesterol and LDL-cholesterol concentrations (P = 0·02 and P = 0·01), whereas the interaction term explained 2·9 % (P = 0·002) and 2·8 % (P = 0·005), respectively. When subjects were divided into four groups according to the median of cholesterol (290·8 mg) and -115G>A genotypes, high cholesterol intake was associated with higher cholesterol levels in -115A carriers. Similar results were observed for c.-840C>A and c.-1830T>C. These results suggest that cholesterol intake interacts with LXRα variants to modulate the plasma lipid profile