955 resultados para Secular perturbation


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Addition of a saturated fatty acid (SFA) induced a strong increase in heat shock (HS) mRNA transcription when cells were heat-shocked at 37 degrees C, whereas treatment with an unsaturated fatty acid (UFA) reduced or eliminated the level of HS gene transcription at 37 degrees C. Transcription of the delta 9-desaturase gene (Ole1) of Histoplasma capsulatum, whose gene product is responsible for the synthesis of UFA, is up-regulated in a temperature-sensitive strain. We show that when the L8-14C mutant of Saccharomyces cerevisiae, which has a disrupted Ole1 gene, is complemented with its own Ole1 coding region under control of its own promoter or Ole1 promoters of H. capsulatum, the level of HS gene transcription depends on the activity of the promoters. Fluorescence anisotropy of mitochondrial membranes of completed strains corresponded to the different activity of the Ole1 promoter used. We propose that the SFA/UFA ratio and perturbation of membrane lipoprotein complexes are involved in the perception of rapid temperature changes and under HS conditions disturbance of the preexisting membrane physical state causes transduction of a signal that induces transcription of HS genes.

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To probe the protein environment of an ion channel, we have perturbed the structure of a transmembrane domain by substituting side chains with those of two different sizes by using site-specific mutagenesis. We have used Trp and Ala as a high- and a low-impact perturbation probe, respectively, to replace each of 18 consecutive residues within the putative second transmembrane segment, M2, of an inwardly rectifying potassium channel, ROMK1. Our rationale is that a change in the channel function as a consequence of these mutations at a particular position will reflect the structural environment of the altered side chain. Each position can then be assigned to one of three classes of environments, as grated by different levels of perturbation: very tolerant (channel functions with both Trp and Ala substitutions), tolerant (function preserved with Ala but not with Trp substitution), and intolerant (either Ala or Trp substitution destroys function). We identify the very tolerant environment as being lipid-facing, tolerant as protein-interior-facing, and intolerant as pore-facing. We observe a strikingly ordered pattern of perturbation of all three environmental classes. This result indicates that M2 is a straight alpha-helix.

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The strong presence of religious institutions in Latin America, especially the Roman Catholic Church, and their participation in the creation and implementation of public policy within a sovereign state can be counter-productive for the social development and progress of that specific country. Argentina and Uruguay and the social controversy of social issues of abortion and same-sex marriage are used as examples to establish the accuracy of the above statement. Historical, statistical, and legislative information about both topics in both countries show that the political power that the Roman Catholic Church has in the region is more an outdated influence than a reality, and the principle of secularization appears to be the most stabilizing philosophy for modern nations.

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Una economía necesita una fuerte inversión para mantener una situación de pleno empleo. La hipótesis del estancamiento secular se plantea cuando una inversión deficiente impide el crecimiento económico. El importante impacto de estos desajustes ha provocado que la hipótesis haya ganado importancia en los últimos años. Summers (2014a) expone una serie de evidencias a su favor en el contexto actual de la economía estadounidense. Tomando su estudio como referencia, en este trabajo se intenta replicar el análisis en la economía española. Este descenso en la propensión a invertir se refleja en un cambio en el equilibrio de la economía y se vincula a la caída del tipo de interés real de equilibrio. Por tanto, se analizará la caída en los tipos de interés reales a partir de una estimación de la tasa de inflación en España. Reuniendo los resultados obtenidos, se extrae una conclusión sobre la hipótesis principal y se aportan y discuten otras teorías alternativas relevantes.

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In this thesis I argue that dominant ways of imagining modernity constitute a modern imaginary that carries with it particular expectations concerning modern places, spaces, emotions, and affects as well as expectations concerning the place of religion and enchantment in the modern world. I argue that this modern imaginary and the expectations it entails works to conceal and trivialize supra-rational beliefs and behaviours in scholarship but also in the lives of individuals. I focus on one particular subset of the supra-rational beliefs and behaviours that modern imaginary conceals and trivializes, namely beliefs and behaviours associated with lucky and protective objects. I also focus on the ways the modern imaginary conceals the presence and prevalence of these objects and the beliefs and behaviours they entail in one particular context, namely Montréal, Québec. I argue that these supra-rational beliefs and behaviours constitute a subjunctive mode for understanding and experiencing daily life and describe how the modern imaginary works to discredit this subjunctive register. Finally, I argue that scholars must begin to recognize and examine this subjunctive mode and the playful engagement with half-belief it involves.

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Mode of access: Internet.

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