Ventilatory Response To Carbon Dioxide Stimuli In Aged Humans

This thesis examined age-related changes in the ventilatory response to exercise and in the ventilatory response to inhaled carbon dioxide (CO{dollar}\sb2{dollar}) at rest. Specifically, the purposes were to: (1) examine the ventilatory response to CO{dollar}\sb2{dollar} production (VCO{dollar}\sb2{dollar}) during graded exercise below the ventilation threshold (T{dollar}\sb{lcub}\rm \.VE{rcub}{dollar}) in men and women aged 55 to 86 yrs, (2) determine the ventilatory response to CO{dollar}\sb2{dollar} at rest and evaluate the CO{dollar}\sb2{dollar} sensitivity of the central and peripheral chemoreceptors in young (YS, n = 7, 28.3 yrs) and old (OS, n = 11, 76.1 yrs) humans, and (3) determine the temporal parameters of the ventilatory response to CO{dollar}\sb2{dollar} in young (YS, n = 4, 27.0 yrs) and old (OS, n = 5, 74.2 yrs) men.;The first study showed significant positive relationship between the ventilatory response to VCO{dollar}\sb2{dollar}, referred to as {dollar}\Delta{dollar}V{dollar}\sb{lcub}\rm E{rcub}/\Delta{dollar}VCO{dollar}\sb2{dollar}, and advancing age, increasing by 0.29/yr for men and by 0.20/yr for women. At a common metabolic demand (VCO{dollar}\sb2{dollar} = 1.0 {dollar}\ell{dollar} min{dollar}\sp{lcub}-1{rcub}{dollar}), V{dollar}\sb{lcub}\rm E{rcub}{dollar} was 14% higher in men aged 80-86 yrs compared to men aged 55-64 yrs while for women, there were no differences between age groupings. The men aged 75 to 86 yrs appear to have reached the appropriate exercise V{dollar}\sb{lcub}\rm E{rcub}{dollar} primarily by an increase in breathing frequency (f{dollar}\sb{lcub}\rm b{rcub}{dollar}) with a levelling off of V{dollar}\sb{lcub}\rm T{rcub}{dollar}. The increased ventilatory response to VCO{dollar}\sb2{dollar} with advancing age may be related to an age-dependent increase in dead-space ventilation (V{dollar}\sb{lcub}\rm D{rcub}{dollar}) and to a greater non-uniformity of ventilation-perfusion ratio.;In the second study, the ventilatory responses to CO{dollar}\sb2{dollar} (eucapnia and hypercapnia) were determined in hyperoxia and hypoxia and, for each subject, the ventilatory responses were fitted to the Lloyd equation, V{dollar}\sb{lcub}\rm E{rcub}{dollar} = S(P{dollar}\sb{lcub}\rm ET{rcub}{dollar}CO{dollar}\sb2{dollar} - B) for the determination of the CO{dollar}\sb2{dollar} sensitivity (S). In hypercapnia, hypoxic V{dollar}\sb{lcub}\rm E{rcub}{dollar} was 24% lower in OS (39.9 {dollar}\pm{dollar} 2.7 (SE), {dollar}\ell\cdot{dollar}min{dollar}\sp{lcub}-1{rcub}){dollar} compared to YS (52.2 {dollar}\pm{dollar} 3.2) while there were no age differences in hyperoxic V{dollar}\sb{lcub}\rm E{rcub}{dollar}. In hypoxia, S was significantly lower in OS (3.25 {dollar}\pm{dollar} 0.38 {dollar}\ell\cdot{dollar}min{dollar}\sp{lcub}-1{rcub}\cdot{dollar} Torr{dollar}\sp{lcub}-1{rcub}{dollar}) compared to YS (4.76 {dollar}\pm{dollar} 0.37) and appeared to have resulted from a lower peripheral chemoreflex CO{dollar}\sb2{dollar} sensitivity (OS, 0.86 {dollar}\pm{dollar} 0.21 {dollar}\ell\cdot{dollar}min{dollar}\sp{lcub}-1{rcub}\cdot{dollar}Torr{dollar}\sp{lcub}-1{rcub}{dollar}; YS, 2.16 {dollar}\pm{dollar} 0.43).;Finally, the third study determined the ventilatory response to CO{dollar}\sb2{dollar} in euoxia, hyperoxia, and mild hypoxia. A double component exponential model was used to estimate the central and peripheral chemoreflex gains (g{dollar}\sb{lcub}\rm c{rcub}{dollar},g{dollar}\sb{lcub}\rm p{rcub}{dollar}), time constants of the responses ({dollar}\tau\sb{lcub}\rm c{rcub}{dollar},{dollar}\tau\sb{lcub}\rm p{rcub}{dollar}), and time delays (T{dollar}\sb{lcub}\rm c{rcub}{dollar},T{dollar}\sb{lcub}\rm p{rcub}{dollar}). YS and OS showed similar characteristics for T{dollar}\sb{lcub}\rm c{rcub}{dollar}, T{dollar}\sb{lcub}\rm p{rcub}{dollar}, {dollar}\tau\sb{lcub}\rm c{rcub}{dollar}, and {dollar}\tau\sb{lcub}\rm p{rcub}{dollar}. In hypoxia, g{dollar}\sb{lcub}\rm c{rcub}{dollar} and g{dollar}\sb{lcub}\rm p{rcub}{dollar} were significantly smaller for OS (g{dollar}\sb{lcub}\rm c{rcub}{dollar}, OS = 1.27 {dollar}\pm{dollar} 0.10 {dollar}\ell\cdot{dollar}min{dollar}\sp{lcub}-1{rcub}\cdot{dollar}Torr{dollar}\sp{lcub}-1{rcub}{dollar} and YS = 2.07 {dollar}\pm{dollar} 0.23, p = 0.0104; g{dollar}\sb{lcub}\rm p{rcub}{dollar}, OS = 0.91 {dollar}\pm{dollar} 0.08 and YS = 1.28 {dollar}\pm{dollar} 0.14, p = 0.0481). This study demonstrated that the ventilatory responses to CO{dollar}\sb2{dollar} in euoxia and hyperoxia are similar for young and older men while in hypoxia, the response in older men is characterized by lower gains for the central and peripheral chemoreflex loops.;These studies have determined the ventilatory response to VCO{dollar}\sb2{dollar} during exercise and the ventilatory response to inhaled CO{dollar}\sb2{dollar} at rest and suggest possible age-related alterations in the mechanisms that control these responses in the elderly

Early Dark Energy Can Resolve The Hubble Tension

Early dark energy (EDE) that behaves like a cosmological constant at early times (redshifts $z\gtrsim3000$) and then dilutes away like radiation or faster at later times can solve the Hubble tension. In these models, the sound horizon at decoupling is reduced resulting in a larger value of the Hubble parameter $H_0$ inferred from the cosmic microwave background (CMB). We consider two physical models for this EDE, one involving an oscillating scalar field and another a slowly-rolling field. We perform a detailed calculation of the evolution of perturbations in these models. A Markov Chain Monte Carlo search of the parameter space for the EDE parameters, in conjunction with the standard cosmological parameters, identifies regions in which $H_0$ inferred from {\it Planck} CMB data agrees with the SH0ES local measurement. In these cosmologies, current baryon acoustic oscillation and supernova data are described as successfully as in \LCDM, while the fit to {\it Planck} data is slightly improved. Future CMB and large-scale-structure surveys will further probe this scenario.Comment: v1: 4p+appendix, 3 figures. v2: small changes, notably estimates of bayesian evidence. matches the version published in PR

Effect of incubation temperature on the development of lactic acid bacteria and their phages

Thirty-one strains of mesophilic and thermophilic lactic acid bacteria and their respective phages were tested for their minimum, optimum and maximum multiplication temperatures. Culture growth was strongly influenced by temperature during the first few hours of incubation, but less so after 24 h. Most of the phages showed the same pattern of development as their hosts, but one phage lysing a thermophilic lactobacillus and 3 phages lysing mesophilic streptococci proved temperature-sensitive, having a lower maximum temperature than that of their hosts. One phage was unusual in that its minimum development temperature was 7 °C above that of its host. Differences in temperature sensitivity were insufficient to reduce risk of phage infection by temperature control in industrial processe

Innovation and value creation in university-industry research centres in the canadian forest products industry

As the forest products industry evolves into a modern industry based on cutting-edge industrial and management research, the prevalence and importance of university research centres have gained importance. Although there has been increased funding and attention given to university-industry research centres from policy makers and researchers, little is still known about the benefits or value that these collaborations provide and create for firms. Applied academic research requires the active participation of researchers and practitioners. In the Canadian forest products industry, there are other important actors that need to be considered, the federal and provincial governments as owners and regulators of the resource and funders of research and development projects and intermediary organisations who are often charged with transforming academic results into tools and methods able to be implemented into industry firms. This paper presents the results of three comparative case studies of university-industry research centres operating in the Canadian forest products industry through an exploration of their knowledge and technology transfer processes. The goal is to better understand the value that has been created for the four main groups of actors involved though informal and formal transfer processes and which processes are best suited for different types of knowledge

Measuring value in the innovation processes of university-industry research centres

There is increasing interest in new research relationships in the form of university-industry partnerships, by governments, universities, intermediary organisations and industry. These collaborations create value, however the value perceived, created and captured by the different actors in the innovation value network are different. However, based on the literature we can say that these values have to be present for all actors, at each phase, for the innovation process to continue. This paper presents a framework that illustrates a multi- actor view of the innovation process and associated values. It is hoped that this matrix can lead to new insight for researchers, practitioners and policy makers to manage better the innovation value network by facilitating the five phases of the innovation value network: policy making and grant process, idea generation and basic research, knowledge and technology development, knowledge and technology transfer and application of knowledge and technologies created by these research centres. Copyright © 2010 Inderscience Enterprises Ltd

Un modèle de qualité logicielle basé sur une architecture favorisant l'agrégation des données selon le processus d'analyse hiérarchique

Philosophie de la qualité -- Philosophie de l'activité de mesure logicielle -- Introduction à la modélisation de la qualité logicielle -- Architecture des modèles de qualité logicielle -- Attributs externes : les facteurs et critères de qualité -- Les attributs internes de qualité : les métriques logicielles -- Agrégation des données -- Le modèle de qualité logicielle développé