Cohesive geometry of Cryptococcus neoformans distribution mediates flower-like biofilm development

Microbial biofilms are highly structured and dynamic communities, in which phenotypic diversification allows microorganisms to adapt to different environments under distinct conditions. Biofilms are ubiquitous in nature and colonize many niches of the human body and implanted medical devices, being an important factor in Cryptococcus neoformans infections. A new approach was used to characterize the underlying geometrical distribution of C. neoformans cells during the adhesion stage of biofilm formation. Geometrical aspects of adhered cells were calculated from the Delaunay triangulations and Voronoi diagrams obtained from scanning electron microscopy images (SEM). A correlation between increased biofilm formation and higher ordering of the underlying cell distribution was found. Mature biofilm aggregates were analyzed by applying a novel protocol developed for ultrastructure visualization of cryptococcal cells by SEM. Flower-like clusters consisting of cells embedded in a dense layer of extracellular matrix were observed as well as morphotype switches related to biofilm formation and distinct levels of spatial organization: adhered cells, clusters of cells and community of clusters. The results add insights into yeast motility during the dispersion stage of biofilm formation. This work emphasizes the importance of cellular organization for biofilm growth and may represent novel approaches to establish potential targets for the inhibition and disruption of biofilms with clinical relevance

Sociobiologia de Cryptococcus spp. : de comunidades estruturadas à dinâmica de populações

Microrganismos podem alternar comportamentos individual e coletivo em resposta a interações positivas ou negativas. Em patógenos, muitas dessas interações influenciam importantes determinantes de virulência, como: formação de biofilme, plasticidade fenotípica e secreção de metabólitos tóxicos. Esta tese explora as interações do patógeno humano Cryptococcus spp. por meio de quatro estudos, cada um evidenciando aspectos complementares em sociobiologia. O estudo (i) demonstrou que a organização geométrica das células na etapa inicial da formação de biofilme é um requisito importante para o desenvolvimento de ultraestrutura madura. Em (ii) diferentes morfotipos capsulares foram identificados e classificados por modelos computacionais. O estudo (iii) abordou as interações interespecíficas entre Cryptococcus neoformans e a bactéria Serratia marcescens. Nessa competição, um interessante padrão foi observado: a bactéria migrou em direção ao fungo impactando a viabilidade celular e determinantes de virulência de C. neoformans. Em (iv) as interações inter-reinos de C. neoformans foram estudadas em um nível maior de complexidade: uma comunidade composta por 8 microrganismos relevantes no trato respiratório foi utilizada para explorar a dinâmica e montagem de populações. Os resultados demonstraram a existência de estados alternativos de equilíbrio dominados por importantes patógenos, bem como os mecanismos que governam essas comunidades.Microorganisms modulate their behavior both individually and collectively in response to interactions with other microorganisms. For pathogens in particular, such interactions influence key virulence factors such as biofilm formation, phenotypic plasticity, and toxin secretion. This thesis explores the interactions of the human pathogen Cryptococcus spp. in four studies, each focusing on a complementary aspect of microbial sociobiology. The first study (i) demonstrated that the geometric organization of cells in the initial step of biofilm formation is an important requirement for the development of mature ultrastructures. In the second study (ii), different capsular morphotypes were identified and classified by computational modeling. The third study (iii) focused on the interspecies interactions between Cryptococcus neoformans and the bacteria Serratia marcescens. An interesting phenomenon was observed in those competitions: the bacteria consistently migrated toward the fungus, impacting the latter’s viability and virulence factors. Finally, in study (iv), the cross– kingdom interactions of C. neoformans were examined at a higher degree of complexity: a set of eight microorganisms relevant to the respiratory tract, including C. neoformans, was used to investigate population dynamics and community assembly. The results revealed the existence of alternative stable states dominated by important pathogens, in addition to the mechanisms that govern such communities

Pricing strategies : optimal price gap between private labels and national brands

The importance of Private Labels for retailers in the modern grocery distribution sector increased their responsibilities when defining price strategies. In recent years the literature has been paying attention to the shift from an inside out to outside in approach when defining prices. This present thesis intents to focus on pricing strategies for Private Labels, centering in the development of a consumer oriented price definition by looking on the optimal price gap between Private Labels and National Brands. Analyzing the Portuguese Market, the goal is to understand the importance of the price comparison between private labels and national brands. The importance of price comparison is essential to understand how the selling price gap will have an influence on consumer’s behavior. The ultimate objective is to be able to give some insights when defining pricing strategies and to understand how manufacturers of national brands can react to competitive moves from retailers. It was concluded that consumers compare more prices within the store than between different stores, enhancing the importance of the price gap as a visible cue with an influence on the consumer behavior. Another conclusion was that the price gap should be tailored according to the nature of the product and the competitive category landscape. Yet, managers should not neglect competitors’ PL prices, because in the end price adjustments should not lead to an overall higher “basket price” compared to competitors, which will be translated as a decrease performance in the price image of the banner

Galaxy Cosmological Mass Function

We study the galaxy cosmological mass function (GCMF) in a semi-empirical relativistic approach using observational data provided by galaxy redshift surveys. Starting from the theory of Ribeiro & Stoeger (2003, arXiv:astro-ph/0304094) between the mass-to-light ratio, the selection function obtained from the luminosity function (LF) data and the luminosity density, the average luminosity $L$ and the average galactic mass $\mathcal{M}_g$ are computed in terms of the redshift. $\mathcal{M}_g$ is also alternatively estimated by a method that uses the galaxy stellar mass function (GSMF). Comparison of these two forms of deriving the average galactic mass allows us to infer a possible bias introduced by the selection criteria of the survey. We used the FORS Deep Field galaxy survey sample of 5558 galaxies in the redshift range $0.5 < z < 5.0$ and its LF Schechter parameters in the B-band, as well as this sample's stellar mass-to-light ratio and its GSMF data. Assuming ${\mathcal{M}_{g_0}} \approx 10^{11} \mathcal{M}_\odot$ as the local value of the average galactic mass, the LF approach results in $L_{B} \propto (1+z)^{(2.40 \pm 0.03)}$ and $\mathcal{M}_g \propto (1+z)^{(1.1\pm0.2)}$. However, using the GSMF results produces $\mathcal{M}_g \propto (1+z)^{(-0.58 \pm 0.22)}$. We chose the latter result as it is less biased. We then obtained the theoretical quantities of interest, such as the differential number counts, to calculate the GCMF, which can be fitted by a Schechter function. The derived GCMF follows theoretical predictions in which the less massive objects form first, being followed later by more massive ones. In the range $0.5 < z < 2.0$ the GCMF has a strong variation that can be interpreted as a higher rate of galaxy mergers or as a strong evolution in the star formation history of these galaxies.Comment: In memory of William R. Stoeger (1943-2014). LaTeX, 8 pages, 7 figures. Minor changes to match version sent to publisher. To appear in "Astronomy and Astrophysics

Assessment of scientific literacy levels of IPB students

[EN] The higher education institutions use scientific and multidisciplinary electronic publication with an anonymous review process and free access to spread technical and scientific knowledge. The Instituto Politécnico de Bragança (IPB) has two electronic journals with the aim of provoking, in young people, the search for wisdom, scientific spirit, respect for authorship and boosting reading and writing skills. This paper presents an exploratory research that evaluated the student's production and publication from IPB by applying a questionary about scientific literacy in the first semester of the 2020/2021 academic year. Participated 102 individuals, majority women, with Portuguese nationality, undergraduate students from Higher School of Education of IPB. The analysis revealed that 71 (69,6%) students have difficulties linked to reading and comprehension skills, just as 82 (80,4%) with scientific writing. That aspect may concern a shortage that debate characteristics of scientific reading, interpretation, and publication. Also, 85 (83.3%) students had not yet published any article, which may require scientific literacy for a better understanding of the scientific method. However, it was possible to note several other types of production developed within the scope of school activities, which may come to stimulate scientific literacy.This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the Project Scope: UIDB/05777/2020.William Lopes, G.; Gonçalves, V. (2022). Assessment of scientific literacy levels of IPB students. En Proceedings INNODOCT/21. International Conference on Innovation, Documentation and Education. Editorial Universitat Politècnica de València. 189-196. https://doi.org/10.4995/INN2021.2021.13631OCS18919

Além do cartão-postal:

Since the end of World War II, lots of rural areas in Europe have been changing themselves deeply. The chaos that describes some major urban zones intensifies a certain “sensibility” around rural lands. Having said that, it has been pretty often aspirations which beholds “rural” cultures and, mostly, landscapes. In light of this, Italy has been seeking some alternatives to value, touristic wise, its “historical” villages and hamlets in conjunction with its most famous cities, such as Rome and Venice. One of the most notorious cases in the country is the municipality of Calcata, where the process of repopulation, as well as aesthetics requalification of its urban equipment, came from straightly the local population itself. This fact has raised among Italians and local midia some favorable notes. Therefore, this article aims at analyzing Calcata’s experience around its cultural heritage and landscape, reflecting about it beyond mere postcards.Desde o fim da Segunda Guerra Mundial, muitas zonas rurais europeias&nbsp;vêm experimentando profundas transformações sócio-espaciais. A agitação que descreve os centros urbanos maiores, acentuada por problemas típicos de tráfego e poluição, intensifica uma certa “sensibilidade” pela cultura e paisagens rurais. Assim, são cada vez mais difusas as aspirações ligadas à contemplação da natureza e nostalgia rural. Diante deste contexto, a Itália tem buscado uma série de alternativas pautadas na valorização e promoção de burgos históricos rurais frente ao glamour e badalação que gravitam em torno de cidades consagradas no cenário turístico mundial, como Roma e Veneza. Um dos exemplos mais notórios do pais é da comuna de Calcata, localidade em que as ações de restauro aplicadas ocorreram de forma individual e autônoma, isto é pela própria população, mantendo o cuidado em se resguardar e valorizar a paisagem que &nbsp;descreve o burgo. Com efeito, gerou-se certa simpatia e entusiasmo de alguns setores econômicos, da mídia e também da sociedade civil. Assim, busca-se interpretar e analisar a experiência italiana de Calcata, decifrando-a para além dos cartões-postais.Desde el final de la Segunda Guerra Mundial, muchas zonas rurales europeas han experimentado profundas transformaciones socio-espaciales. La agitación que describe los centros urbanos más grandes, acentuada por problemas típicos de tráfico y contaminación, intensifica una cierta "sensibilidad" por la cultura y paisajes rurales. Así, son cada vez más difusas las aspiraciones ligadas a la contemplación de la naturaleza y nostalgia rural. Ante este contexto, Italia ha buscado una serie de alternativas pautadas en la valorización y promoción de burgos históricos rurales frente al glamour y la música que gravitan en torno a ciudades consagradas en el escenario turístico mundial, como Roma y Venecia. Uno de los ejemplos más notorios del país es de la comuna de Calcata, localidad en la que las acciones de restauración aplicadas ocurrieron de forma individual y autónoma, es decir por la propia población, manteniendo el cuidado en resguardarse y valorar el paisaje que describe el burgo. En efecto, se generó cierta simpatía y entusiasmo de algunos sectores económicos, de los medios y también de la sociedad civil. Así, se busca interpretar y analizar la experiencia italiana de Calcata, descifrándola más allá de las tarjetas postales

The Seiberg-Witten equations on a surface times a circle

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mathematics, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 63).In this thesis I study the Seiberg-Witten equations on the product of a genus g surface [Sigma] and a circle. I exploit S1 invariance to reduce to the vortex equations on [Sigma] and thus completely describe the Seiberg-Witten monopoles. In the case where the monopoles are not Morse-Bott regular, I explicitly perturb the equations to obtain such a situation and thus find a candidate for the chain complex that calculates the Seiberg-Witten Floer homology groups.by William Manuel Lopes.Ph.D