Dennis Edward Hyde, Letícia Pereira Alves, Daniel Rodrigues Costa Mello
et al.
This article presents the National Parks Astrotourism Potential Index (IASTRO), an innovative tool to evaluate and compare the potential for astro tourism in the 75 Brazilian national parks. IASTRO combines three crucial parameters: night sky quality, open sky probability, and tourism infrastructure, which encompasses the presence of guides and the availability of different experiences of overnight stays. The detailed methodology for data collection and IASTRO calculation is described, including the weighting of parameters, with night sky quality receiving greater weight for its fundamental importance for celestial observation. The results reveal a diverse distribution of IASTRO among the parks, highlighting those located in the Cerrado and Caatinga biomes, which present more favorable night sky and climatological conditions. The in-depth discussion explores the relationship between IASTRO and other factors, such as the number of visitors and the characteristics of the biomes, revealing an untapped potential for astro tourism in many national parks. The study also highlights the importance of tourism infrastructure and simulates how improvements in this aspect can boost astro tourism potential in various parks. The final considerations emphasize IASTRO as a valuable tool for protected area management and for the formulation of public policies, promoting the preservation of the starry sky and the development of astro tourism in a sustainable way. The article concludes that Brazil has enormous potential to become a world-class astro tourism destination, with its national parks offering exceptional conditions for celestial observation and connection with nature. This pioneering study contributes to the field of ecotourism by providing a comprehensive and innovative index to assess the astro tourism potential in national parks. IASTRO can be used by park managers, researchers, tourists, astronomy enthusiasts and policy makers to identify and prioritize parks with greater potential for this activity, assisting in the planning of actions and investments that promote the development of astro tourism in Brazil. In summary, the article presents an innovative index to assess the astro tourism potential in Brazilian national parks, highlighting the importance of night sky quality, open sky probability, and tourism infrastructure. The study reveals an untapped potential for astro tourism in many parks and highlights the importance of investments in tourism infrastructure to boost this activity. IASTRO is presented as a valuable tool for protected area management and for the formulation of public policies, aiming at the sustainable development of astro tourism in Brazil.
Desde tempos imemoriais que os seres humanos olham e tentam perceber o céu. Não sabiam bem o que eram aquelas luzes a brilhar e que se movimentavam de forma repetida. Hoje em dia parece muito fácil, mas demorou muito tempo a consolidar-se a imagem que atualmente temos do céu. E sobretudo, a sabermos qual era a sua composição química. Este artigo pretende fazer uma revisão de divulgação do conhecimento químico que temos do céu e mostrar que as informações químicas são indissociáveis do entendimento que temos hoje do universo.
Neste artigo explicamos o que são as ondas gravitacionais previstas pela teoria da relatividade geral de Einstein, falamos de suas fontes astrofísicas e cosmológicas e dos detectores que foram utilizados para a sua busca. Completamos o artigo com a menção aos detectores futuros, que estão sendo projetados para dar uma nova dimensão à astronomia de ondas gravitacionais e à astronomia multimensageira envolvendo ondas gravitacionais.
Discuto alguns aspectos do chamado “paradigma da luz cansada”, o qual representa uma das possíveis explicações para a dependência do desvio espectral para o vermelho de uma fonte cósmica distante com a sua distância até o observador. A mais popular representação fenomenológica do paradigma é apresentada em algum detalhe. Além disso, sendo o processo físico responsável pelo hipotético fenômeno ainda desconhecido, apresento também uma sugestão para a sua descoberta.
Há mais de 2500 anos, o filósofo grego Tales de Mileto descobriu um teorema geométrico que lhe permitiu avaliar a altura da Grande Pirâmide no Egito comparando o comprimento de sua sombra com o comprimento da sombra projetada pelo bastão vertical ao mesmo tempo. Ao fazer isso, Tales estava usando três definições independentes de linha, e geometria em geral, provenientes de três reinos da física: gravidade, física quântica e atômica, e ótica. No presente trabalho analisamos as implicações físicas e filosóficas da coincidência entre três definições de espaço físico e sua geometria.
Abstract I give a review of the development of the concept of dark matter. The dark matter story passed through several stages from a minor observational puzzle to a major challenge for theory of elementary particles. Modern data suggest that dark matter is the dominant matter component in the Universe, and that it consists of some unknown non-baryonic particles. Dark matter is the dominant matter component in the Universe, thus properties of dark matter particles determine the structure of the cosmic web.
ABSTRACTCells of Coccolithus huxleyi which fail to deposit CaCO3 and form coccoliths often occur as unwanted components in cultures used for studies of calcification. Non‐calcified cells generally cannot be made to recalcify, but they can be removed from cultures by treatment at elevated pH or by a method based on faster sinking of calcified cells. Lowering the concentrations of nitrate, phosphate, or trace metals in the medium did not restore calcifying ability of non‐calcified cells. However, addition of strontium did promote recalcification of decalcified Cricosphaera carterae grown under calcium limitation. Strontium seemed to promote coccolith attachment to cells rather than to affect calcium uptake or coccolith formation itself.
Abstract The aim of the present study is to evaluate the involvement of human neutrophil tyrosine kinase(s) in the signal transduction mechanism of granulocyte-macrophage colony-stimulating factor (GM-CSF). Stimulation of neutrophils with GM-CSF resulted in a time- and dose-dependent phosphorylation of several proteins having estimated molecular weights of approximately 40, 55, 74, 97, 118, and 155 Kd, detected by immunoblot using a monoclonal antibody directed against phosphotyrosine. GM-CSF-induced tyrosine phosphorylation was inhibited in a dose- and time-dependent manner by the tyrosine kinase inhibitor erbstatin. Using this inhibitor, we were able to correlate tyrosine phosphorylation with several functional effects of GM-CSF on human neutrophils. Pretreatment of neutrophils with erbstatin before incubation with GM-CSF completely inhibited the GM-CSF-induced intracellular alkalinization, downregulation of the leukotriene B4 receptor, enhancement of fMet-Leu-Phe-induced intracellular calcium mobilization, as well as the accumulation of mRNA for the proto- oncogene c-fos. Taken together, these data suggest that tyrosine kinase activation in human neutrophils plays a critical regulatory role in both the stimulation and priming of neutrophil function by GM-CSF.
The aim of the present study is to evaluate the involvement of human neutrophil tyrosine kinase(s) in the signal transduction mechanism of granulocyte-macrophage colony-stimulating factor (GM-CSF). Stimulation of neutrophils with GM-CSF resulted in a time- and dose-dependent phosphorylation of several proteins having estimated molecular weights of approximately 40, 55, 74, 97, 118, and 155 Kd, detected by immunoblot using a monoclonal antibody directed against phosphotyrosine. GM-CSF-induced tyrosine phosphorylation was inhibited in a dose- and time-dependent manner by the tyrosine kinase inhibitor erbstatin. Using this inhibitor, we were able to correlate tyrosine phosphorylation with several functional effects of GM-CSF on human neutrophils. Pretreatment of neutrophils with erbstatin before incubation with GM-CSF completely inhibited the GM-CSF-induced intracellular alkalinization, downregulation of the leukotriene B4 receptor, enhancement of fMet-Leu-Phe-induced intracellular calcium mobilization, as well as the accumulation of mRNA for the proto- oncogene c-fos. Taken together, these data suggest that tyrosine kinase activation in human neutrophils plays a critical regulatory role in both the stimulation and priming of neutrophil function by GM-CSF.