Policy Brief No. 13 - Future Canadian Workers: More Educated and More Culturally diversified

This article charts the future transformations of the Canadian labor force population using a microsimulation projection model. The model takes into account differentials in demographic behavior and labor force participation of individuals according to their ethnocultural and educational characteristics. Results of the microsimulation show that Canada\u27s labor force population will continue to increase, but at a slower rate than in the recent past. By 2031, almost one third of the country\u27s total labor force could be foreign-born, and almost all its future increase is expected to be fueled by university graduates, while the less-educated labor force is projected to decline. All projection scenarios show that Canada’s overall participation rate will decline due to the retirement of the Boomers and the slow growth of the workforce. The analyses suggest that the most pertinent driver to be addressed is the differential in the labor force participation rates of the Canadian-born white population and immigrants and visible minorities

Spectroscopie de luminescence et Raman de matériaux moléculaires cristallins et modélisation par la théorie de la fonctionnelle de la densité

Cette thèse présente une série de mesures spectroscopiques (Raman, luminescence) de composés du platine(II) et de l’or(I). Les spectres Raman sont mesurés à température ou pression variable et les transitions vibrationnelles sont attribuées à partir d’une comparaison avec des calculs DFT. Cette approche est particulièrement utile pour des complexes de métaux de transition avec des ligands polyatomiques et un accord quantitatif est obtenu pour certains composés. Des interactions faibles comme les interactions aurophiles entre centres or(I) sont un défi pour les calculs DFT et cela est démontré par la modélisation de xanthates de l’or(I) et de dithiocarbamates de l’or(I). Ces interactions aurophiles sont étudiées par spectroscopie de luminescence à température ou pression variable pour certains dithiocarbamates de l’or(I). Des résultats expérimentaux montrent de grandes variations comme un déplacement bathochromique du maximum de luminescence de -120 cm-1/kbar pour le diéthyldithiocarbamate de l’or(I) avec des chaînes aurophiles linéaires ou une variation de la largeur de la bande de luminescence pour ce même composé. Ces effets sont analysés avec des calculs DFT qui montrent que les distances or(I)-or(I) ainsi que les angles le long de la chaîne sont importants pour les variations et propriétés observées. Les distances intermétalliques sont déterminées par diffraction des rayons-X à température variable pour certains composés de l’or(I) et du platine(II) et la combinaison avec les spectres de luminescence aux mêmes conditions permet de comparer les interactions pour les deux métaux différents. Un modèle empirique de la littérature est utilisé et appliqué quantitativement aux systèmes de l’or(I). Les effets semblent généralement plus petits pour les composés de l’or(I) que pour ceux du platine(II) de la littérature et cette thèse présente la première analyse quantitative de tels effets. La combinaison de structures cristallographiques, de spectres expérimentaux et de calculs DFT amène une compréhension plus quantitative d’effets de structure électronique, moléculaire et supramoléculaire qui déterminent des propriétés spectroscopiques comme l’énergie du maximum de luminescence ou la largeur de la bande de luminescence.This thesis presents a series of spectroscopic measurements (Raman, luminescence) of platinum(II) and gold(I) compounds. The Raman spectra are measured at variable temperature or pressure and the vibrational transitions are assigned by comparison with DFT calculations. This approach is especially useful for metal complexes with polyatomic ligands and a quantitative agreement is achieved for some compounds. Weak interactions such as aurophilic bonding between gold(I) centers are a challenge for DFT calculations as demonstrated by the modeling of gold(I) xanthates and gold(I) dithiocarbamates. These aurophilic interactions are analyzed by variable-temperature and variable-pressure luminescence spectroscopy for some gold(I) dithiocarbamates. Experimental results show great variations such as a bathochromic shift of the luminescence band maximum of -120 cm-1/kbar for the gold(I) diethyldithiocarbamate with linear gold(I) chain structures or a variation of the luminescence bandshape for this very same compound. These effects are analyzed with DFT calculations showing that the gold(I)-gold(I) distances as well as the angles along the chain are important for the observed variations and properties. The intermetallic distances are determined by X-ray diffraction at variable temperature for some gold(I) and platinum(II) compounds and the combination with luminescence spectra at the same conditions allows to compare the interactions for the two different metals. An empirical model from the literature is used and quantitatively applied to the gold(I) systems. Effects seem generally to be smaller for the gold(I) compounds than for platinum(II) compounds from the literature and this thesis presents the first quantitative analysis of such effects, again compared to DFT calculations. The combination of crystal structures, experimental spectra and DFT models leads to a more quantitative understanding of electronic, molecular and supramolecular structural effects determining spectroscopic properties such as luminescence band maxima or bandshapes

Mild hypothermia prevents brain edema and attenuates up-regulation of the astrocytic benzodiazepine receptor in experimental acute liver failure

BACKGROUND/AIMS: Mild hypothermia has proven useful in the clinical management of patients with acute liver failure. Acute liver failure in experimental animals results in alterations in the expression of genes coding for astrocytic proteins including the "peripheral-type" (astrocytic) benzodiazepine receptor (PTBR), a mitochondrial complex associated with neurosteroid synthesis. To gain further insight into the mechanisms whereby hypothermia attenuates the neurological complications of acute liver failure, we investigated PTBR expression in the brains of hepatic devascularized rats under normothermic (37 degrees C) and hypothermic (35 degrees C) conditions. METHODS: PTBR mRNA was measured using semi-quantitative RT-PCR in cerebral cortical extracts and densities of PTBR sites were measured by quantitative receptor autoradiagraphy. Brain pregnenolone content was measured by radioimmunoassay. RESULTS: At coma stages of encephalopathy, animals with acute liver failure manifested a significant increase of PTBR mRNA levels. Brain pregnenolone content and [(3)H]PK 11195 binding site densities were concomitantly increased. Mild hypothermia prevented brain edema and significantly attenuated the increased receptor expression and pregnenolone content. CONCLUSIONS: These findings suggest that an attenuation of PTBR up-regulation resulting in the prevention of increased brain neurosteroid content represents one of the mechanisms by which mild hypothermia exerts its protective effects in ALF.CIH

Contrasting nutritional acclimation of sugar maple (Acer saccharum Marsh.) and red maple (Acer rubrum L.) to increasing conifers and soil acidity as demonstrated by foliar nutrient balances

Sugar maple (Acer saccharum Marshall, SM) is believed to be more sensitive to acidic and nutrient-poor soils associated with conifer-dominated stands than red maple (Acer rubrum L., RM). Greater foliar nutrient use efficiency (FNUE) of RM is likely the cause for this difference. In the context of climate change, this greater FNUE could be key in favoring northward migration of RM over SM. We used the concept of foliar nutrient balances to study the nutrition of SM and RM seedlings along an increasing gradient in forest floor acidity conditioned by increasing proportions of conifers (pH values ranging from 4.39 under hardwoods, to 4.29 under mixed hardwood-conifer stands and 4.05 under conifer-dominated stands). Nutrients were subjected to isometric log-ratio (ilr) transformation, which views the leaf as one closed system and considers interactions between nutrients. The ilr method eliminates numerical biases and weak statistical inferences based on raw or “operationally” log-transformed data. We analyzed foliar nutrients of SM and RM seedlings and found that the [Ca,Mg,K| P,N] and [Ca,Mg| K] balances of SM seedlings were significantly different among soil acidity levels, whereas they did not vary for RM seedlings. For SM seedlings, these differences among soil acidity levels were due to a significant decrease in foliar Ca and Mg concentrations with increasing forest floor acidity. Similar differences in foliar balances were also found between healthy and declining SM stands estimated from literature values. Conversely, foliar balances of RM seedlings did not differ among soil acidity levels, even though untransformed foliar nutrient concentrations were significantly different. This result highlights the importance of using ilr transformation, since it provides more sensitive results than standard testing of untransformed nutrient concentrations. The lower nutrient requirements of RM and its greater capacity to maintain nutrient equilibrium are factors that could explain its competitive success and recent northward expansion. This study underscores the importance of using nutrient balances to study the redistribution of plant species in natural ecosystems under climate change

Precipitation and relative humidity favours tree growth while air temperature and relative humidity respectively drive winter stem shrinkage and expansion

Forest ecosystems have a major role in sequestering atmospheric CO2 and as such, their resilience is of upmost importance. In the boreal forest, trees grow only during a short period when air temperature is favourable. During winter, trees have specific mechanisms to survive in the cold air temperature. In order to understand the response of trees to a changing climate, this study assessed the influence of environmental variables on three phases of tree radial variation (i.e., growth, shrinkage and expansion) during three periods of the year (i.e., growing season, freeze–thaw period, and winter). The three phases were extracted from stem radial variation measured for as much as 11 years on 12 balsam fir [Abies balsamea (L.) Mill.] trees located in a cold and humid boreal forest of eastern Canada. The random forest algorithm was used to model each phase during each period. Our results show that tree growth increased with high precipitation and high relative humidity. Stem shrinkage was affected mostly by solar radiation, precipitation and vapour pressure deficit during the growing season and was likely caused by tree transpiration. During both the freeze–thaw and winter season periods, stem shrinkage increased with decreasing air temperature. During the growing season, stem expansion was related to 1-day-lag solar radiation and 1-day-lag vapour pressure deficit, which are the same variables associated with shrinkage the preceding day. Stem expansion increased with increasing air temperature and relative humidity during the freeze–thaw and winter season periods, respectively. This study shows that sink-driven tree growth is promoted mostly under humid conditions while antecedent dry and warm conditions are required during the growing season for trees to assimilate carbon through photosynthesis

Dynein Light Chain Tctex-Type 1 Modulates Orexin Signaling through Its Interaction with Orexin 1 Receptor

Orexins (OX-A, OX-B) are neuropeptides involved in the regulation of the sleep-wake cycle, feeding and reward, via activation of orexin receptors 1 and 2 (OX1R, OX2R). The loss of orexin peptides or functional OX2R has been shown to cause the sleep disorder, narcolepsy. Since the regulation of orexin receptors remains largely undefined, we searched for novel protein partners of the intracellular tail of orexin receptors. Using a yeast two-hybrid screening strategy in combination with co-immunoprecipitation experiments, we found interactions between OX1R and the dynein light chains Tctex-type 1 and 3 (Dynlt1, Dynlt3). These interactions were mapped to the C-terminal region of the dynein light chains and to specific residues within the last 10 amino acids of OX1R. Hence, we hypothesized that dynein light chains could regulate orexin signaling. In HEK293 cells expressing OX1R, stimulation with OX-A produced a less sustained extracellular signal-regulated kinases 1/2 (ERK1/2) activation when Dynlt1 was co-expressed, while it was prolonged under reduced Dynlt1 expression. The amount of OX1R located at the plasma membrane as well as the kinetics and extent of OX-A-induced internalization of OX1R (disappearance from membrane) were not altered by Dynlt1. However, Dynlt1 reduced the localization of OX1R in early endosomes following initial internalization. Taken together, these data suggest that Dynlt1 modulates orexin signaling by regulating OX1R, namely its intracellular localization following ligand-induced internalization

The role of antibiosis in the antagonism of different bacteria towards Helminthosporium solani, the causal agent of potato silver scurf

Bacterial antagonists of Helminthosporium solani were submitted to different tests in order to determine the role of antibiosis in their antagonistic interaction. Among the bacterial strains tested, seven (Alcaligenes piechaudii, Aquaspirillum autotrophicum, Cellulomonas fimi, Pseudomonas chlororaphis, Pseudomonas putida (strains 94-19 and E-30) and Streptomyces griseus) were shown to produce agar diffusible metabolites inhibiting H. solani mycelial growth and/or conidial germination. Differential activity was revealed when diffusible metabolites were extracted from either pure cultures of these antagonists or dual culture in the presence of H. solani. The results presented indicate that the methodology employed could be a decisive factor in whether or not antibiosis can be identified as a mode of action of biocontrol agents.Des antagonistes bactériens envers Helminthosporium solani ont été soumis à différents essais en vue de déterminer le rôle de l'antibiose dans l'antagonisme observé. Parmi les souches bactériennes évaluées, sept (Alcaligenes piechaudii, Aquaspirillum autotrophicum, Cellulomonas fimi, Pseudomonas chlororaphis, Pseudomonas putida (souches 94-19 et E-30) et Streptomyces griseus) ont produit dans le milieu gélosé des métabolites inhibant la croissance mycélienne et/ou la germination des conidies de H. solani. Les métabolites produits en culture pure et en culture mixte ont présenté une activité différente sur la croissance mycélienne de H. solani. Les résultats présentés indiquent que la méthodologie employée peut être un facteur déterminant dans l'identification de l'antibiose comme mode d'action d'un agent antagoniste