91 resultados para 1540
Resumo:
The different aspects of magic became an essential ingredient of bucolic universe since the origin of pastoral genre. Within an idealized and utopic frame, magic built a bridge towards transcendence, and balanced the disharmony created by human love emotions within Arcadian microcosm. This concept of magic became infused to Sixteenth century pastoral novel through Neoplatonism and Hermetic tradition. From a narratological point of view, magic episodes became indispensable to complete the philosophical meaning of the works. Lope de Vega, in La Arcadia, published in 1598, fully participated from this tradition, though he will approach the convention from a particular dramatic-like perspective. And it was precisely in pastoral comedias where the Fénix ends up deconstructing bucolic code to remodel it as a mere vestige of the tradition and treat magic as a humorous ingredient.
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Departing from the concepts of visualism and theatricality understood as the base of the world view of an epoch, a reflection about the presence of a pictorial-based expressiveness in the performance of Lope’s comedias de santos is suggested. Besides the analysis of the suitable contexts and staging procedures associated to the appearance of sacred images on stage, static performances, closer to painting than to drama, are also taken into account as a device which contribute to create that transcendent meaning which is essential to hagiographical comedias.
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Intestinal dendritic cells (DCs) are believed to sample and present commensal bacteria to the gut-associated immune system to maintain immune homeostasis. How antigen sampling pathways handle intestinal pathogens remains elusive. We present a murine colitogenic Salmonella infection model that is highly dependent on DCs. Conditional DC depletion experiments revealed that intestinal virulence of S. Typhimurium SL1344 DeltainvG mutant lacking a functional type 3 secretion system-1 (DeltainvG)critically required DCs for invasion across the epithelium. The DC-dependency was limited to the early phase of infection when bacteria colocalized with CD11c(+)CX3CR1(+) mucosal DCs. At later stages, the bacteria became associated with other (CD11c(-)CX3CR1(-)) lamina propria cells, DC depletion no longer attenuated the pathology, and a MyD88-dependent mucosal inflammation was initiated. Using bone marrow chimeric mice, we showed that the MyD88 signaling within hematopoietic cells, which are distinct from DCs, was required and sufficient for induction of the colitis. Moreover, MyD88-deficient DCs supported transepithelial uptake of the bacteria and the induction of MyD88-dependent colitis. These results establish that pathogen sampling by DCs is a discrete, and MyD88-independent, step during the initiation of a mucosal innate immune response to bacterial infection in vivo.
Resumo:
Individuals differ in their preference for processing information on the basis of taxonomic, feature-based similarity, or thematic, relation-based similarity. These differences, which have been investigated in a recently emerging research stream in cognitive psychology, affect innovative behavior and thus constitute an important antecedent of individual performance in research and development (R&D) that has been overlooked so far in the literature on innovation management. To fill this research gap, survey and test data from the employees of a multinational information technology services firm are used to examine the relationship between thematic thinking and R&D professionals' individual performance. A moderated mediation model is applied to investigate the proposed relationships of thematic thinking and individual-level performance indicators. Results show a positive relationship between thematic thinking and innovativeness, as well as individual job performance. While the results do not support the postulated moderation of the innovativeness–job performance relationship by employees' political skill, they show that the relationship between thematic thinking and job performance is fully mediated by R&D professionals' innovativeness. The present study is thus the first to reveal a positive relationship between thematic thinking and innovative performance.
Resumo:
The selenoenzyme glutathione peroxidase 4 (Gpx4) is a major scavenger of phospholipid hydroperoxides. Although Gpx4 represents a key component of the reactive oxygen species-scavenging network, its relevance in the immune system is yet to be defined. Here, we investigated the importance of Gpx4 for physiological T cell responses by using T cell-specific Gpx4-deficient mice. Our results revealed that, despite normal thymic T cell development, CD8(+) T cells from T(ΔGpx4/ΔGpx4) mice had an intrinsic defect in maintaining homeostatic balance in the periphery. Moreover, both antigen-specific CD8(+) and CD4(+) T cells lacking Gpx4 failed to expand and to protect from acute lymphocytic choriomeningitis virus and Leishmania major parasite infections, which were rescued with diet supplementation of high dosage of vitamin E. Notably, depletion of the Gpx4 gene in the memory phase of viral infection did not affect T cell recall responses upon secondary infection. Ex vivo, Gpx4-deficient T cells rapidly accumulated membrane lipid peroxides and concomitantly underwent cell death driven by ferroptosis but not necroptosis. These studies unveil an essential role of Gpx4 for T cell immunity.
Reviving extinct Mediterranean forest communities may improve ecosystem potential in a warmer future
Resumo:
The Mediterranean Basin is the region of Europe most vulnerable to negative climate-change impacts, including forest decline, increased wildfire, and biodiversity loss. Because humans have affected Mediterranean ecosystems for millennia, it is unclear whether the region's native ecosystems were more resilient to climate change than current ecosystems, and whether they would provide sustainable management options if restored. We simulated vegetation with the LandClim model, using present-day climate as well as future climate-change scenarios, in three representative areas that encompass a broad range of Mediterranean conditions and vegetation types. Sedimentary pollen records that document now-extinct forests help to validate the simulations. Forests modeled under present climate closely resemble the extinct forests when human disturbance is limited; under future scenarios, characterized by increased temperatures and decreased precipitation, extinct forests are projected to re-emerge. When combined with modeling, paleoecological evidence reveals the potential of native vegetation to re-establish under current and future climate conditions, and provides a template for novel management strategies to maintain forest productivity and biodiversity in a warmer and drier future.
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Innate lymphoid cells (ILCs) are critical for maintaining epithelial barrier integrity at mucosal surfaces; however, the tissue-specific factors that regulate ILC responses remain poorly characterized. Using mice with intestinal epithelial cell (IEC)-specific deletions in either inhibitor of κB kinase (IKK)α or IKKβ, two critical regulators of NFκB activation, we demonstrate that IEC-intrinsic IKKα expression selectively regulates group 3 ILC (ILC3)-dependent antibacterial immunity in the intestine. Although IKKβ(ΔIEC) mice efficiently controlled Citrobacter rodentium infection, IKKα(ΔIEC) mice exhibited severe intestinal inflammation, increased bacterial dissemination to peripheral organs, and increased host mortality. Consistent with weakened innate immunity to C. rodentium, IKKα(ΔIEC) mice displayed impaired IL-22 production by RORγt(+) ILC3s, and therapeutic delivery of rIL-22 or transfer of sort-purified IL-22-competent ILCs from control mice could protect IKKα(ΔIEC) mice from C. rodentium-induced morbidity. Defective ILC3 responses in IKKα(ΔIEC) mice were associated with overproduction of thymic stromal lymphopoietin (TSLP) by IECs, which negatively regulated IL-22 production by ILC3s and impaired innate immunity to C. rodentium. IEC-intrinsic IKKα expression was similarly critical for regulation of intestinal inflammation after chemically induced intestinal damage and colitis. Collectively, these data identify a previously unrecognized role for epithelial cell-intrinsic IKKα expression and TSLP in regulating ILC3 responses required to maintain intestinal barrier immunity.
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INTRODUCTION Cardiac myocytes utilize three high-capacity Na transport processes whose precise function can determine myocyte fate and the triggering of arrhythmias in pathological settings. We present recent results on the regulation of all three transporters that may be important for an understanding of cardiac function during ischemia/reperfusion episodes. METHODS AND RESULTS Refined ion selective electrode (ISE) techniques and giant patch methods were used to analyze the function of cardiac Na/K pumps, Na/Ca exchange (NCX1), and Na/H exchange (NHE1) in excised cardiac patches and intact myocytes. To consider results cohesively, simulations were developed that account for electroneutrality of the cytoplasm, ion homeostasis, water homeostasis (i.e., cell volume), and cytoplasmic pH. The Na/K pump determines the average life-time of Na ions (3-10 minutes) as well as K ions (>30 minutes) in the cytoplasm. The long time course of K homeostasis can determine the time course of myocyte volume changes after ion homeostasis is perturbed. In excised patches, cardiac Na/K pumps turn on slowly (-30 seconds) with millimolar ATP dependence, when activated for the first time. In steady state, however, pumps are fully active with <0.2 mM ATP and are nearly unaffected by high ADP (2 mM) and Pi (10 mM) concentrations as may occur in ischemia. NCX1s appear to operate with slippage that contributes to background Na influx and inward current in heart. Thus, myocyte Na levels may be regulated by the inactivation reactions of the exchanger which are both Na- and proton-dependent. NHE1 also undergo strong Na-dependent inactivation, whereby a brief rise of cytoplasmic Na can cause inactivation that persists for many minutes after cytoplasmic Na is removed. This mechanism is blocked by pertussis toxin, suggesting involvement of a Na-dependent G-protein. Given that maximal NCX1- and NHE1-mediated ion fluxes are much greater than maximal Na/K pump-mediated Na extrusion in myocytes, the Na-dependent inactivation mechanisms of NCX1 and NHE1 may be important determinants of cardiac Na homeostasis. CONCLUSIONS Na/K pumps appear to be optimized to continue operation when energy reserves are compromised. Both NCX1 and NHE1 activities are regulated by accumulation of cytoplasmic Na. These principles may importantly control cardiac cytoplasmic Na and promote myocyte survival during ischemia/reperfusion episodes by preventing Ca overload.
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We develop a monopolistic competition model with nonhomothetic factor input bundles where increasing quality requires increasing use of skilled workers. As a result more skill abundant countries export higher quality, higher priced goods. Using a multicountry dataset we test and confirm the findings in Schott (2004) of a positive effect of skill abundance on unit values identified with US data. We extend the core model with per unit trade costs leading to the Washington-apples effect that goods shipped over larger distance are of higher quality. The combination of high-quality goods being relatively skill intensive with the Washington-apples effect implies that countries at a larger distance from their trading partners display a higher skill premium. Simulating our model we find that a doubling of distance of a country relative to all its trading partners raises the skill premium in a country by about 2.3 percent.
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Recent evidence suggests that successors do not simply inherit their parents’ firm, but have to pay a certain price. Building on institutional logics literature, we explore successors’ family discount expectations, defined as the rebate expected from parents in comparison to nonfamily buyers when assuming control of the firm. We find that family cohesion increases discount expectations, while successors’ fear of failure and family equity stake in the firm decrease discount expectations. Higher education in business or economics weakens These effects. On average, in our study comprised of 16 countries, successors expect a 57% family discount.
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We argue that greater availability of financial support by the family for creating a new venture entails stronger financial and non-financial obligations. Cognizant of these obligations, potential founders anticipate negative performance implications for the planned firm and threats to the family system in the case of their non-fulfillment. We thus postulate that the formation of actual entrepreneurial intentions is less likely the greater the available financial support. We confirm this by studying a sample of 23,304 respondents from 19 countries and find the negative relationship to be dependent on family cohesion and on individual entrepreneurial self-efficacy.
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We add novel insights to the debate about why individuals choose to start their own firm by comparing entrepreneurial intentions to the intentions to work at a university as an academic and to be employed in a private firm. To model this more complex set of career choices, we examine novel multiplicative aspects of the theory of planned behavior (TPB) and test our hypotheses on survey data of 15,866 students from 13 European countries. Multinomial logistic regression analyses reveal how the different TPB elements influence career preferences and demonstrate the moderating effects of perceived controllability and desirability.