Positivity, rational Schur functions, Blaschke factors, and other related results in the Grassmann algebra

We begin a study of Schur analysis in the setting of the Grassmann algebra, when the latter is completed with respect to the $1$-norm. We focus on the rational case. We start with a theorem on invertibility in the completed algebra, and define a notion of positivity in this setting. We present a series of applications pertaining to Schur analysis, including a counterpart of the Schur algorithm, extension of matrices and rational functions. Other topics considered include Wiener algebra, reproducing kernels Banach modules, and Blaschke factors.Comment: 35 page

Poetry as a resonant method for multi-sensory research

UIDB/00472/2020 UIDP/00472/2020This article explores the potential of poetry for attuning to and expressing resonance in multi-sensory geographies. I argue that poetic inquiry can provide novel ways to address sensory geographies, by shifting the focus from individual senses to a more integrated understanding of how sensory phenomena resonates across bodies and spaces. By doing this, poetry also becomes a resonant method that allows one to merge different subjectivities and express pluriversal worlds. I draw upon Erlmann's discussion of resonance as a way to overcome three dichotomies regarding knowing and the senses that have been recently contested in sensory geographies, namely the dichotomies between reasoning and the affective, the external and internal, and attention and distraction. In order to demonstrate the potential of poetry as a resonant method, I present a poetic exploration of the life of the Staines Reservoirs. The findings of this experiment show that poetry can be a resonant method when the geographer-poet is attuned to the way in which thinking and feeling are intertwined, the ways in which the senses mix themselves in the experience of the world, and the ways in which the world resonates within bodies and bodies echo in the world.publishersversionpublishe

Urban sound : territories, affective atmospheres, and politics

This dissertation approaches issues related to the territories, affective atmospheres and politics of urban sound. The research methodology, underpinned by the concepts and methods of non- and more-than-representational theories, consists on a participatory approach in which research questions, data, and concepts were co-produced by the researcher and a group of twelve participants. I conducted two sets of experiments with the group of participants. In the first set, I conducted a series of sound diaries followed by conversations. In the second set, I conducted a series of go-alongs, which were followed by group interviews. In addition, I conducted two geoethnographic studies – one in Chiado, Lisbon, and another in Quinta da Piedade, Vila Franca de Xira – with the purpose of exploring the research concepts in ecological contexts. The main objective of this thesis is to explore the phenomenology of the urban sonic experience, and the possibilities to intervene in urban territories through sound. By doing this, the thesis contributes toward advancing knowledge in the field of sonic geographies, namely by increasing knowledge about the urban sonic experience. I argue that the phenomenology of the urban sonic experience emerges from the simultaneity of listening and soundmaking, both of which are more-than-representational acts that intertwine affective sensing and ethico-political reasoning. Furthermore, I show that sonic interventions in urban space that engage with these more-than-representational acts, such as artistic practices or street football, have the capacity of altering urban territories by acting on the distribution of the sensible or by enacting worlds. The thesis is composed by four individual but related studies. Study#1 aims to understand the phenomenology of moments of transition between sonic environments in the urban context through the analysis of a series of experiments conducted with the group of volunteers. I conceptualise the phenomenology of moments of transitions as sonic first impressions, drawing upon the concept of first impression by Tonino Griffero. Study#2 extends the exploration of the sonic first impression by investigating how it can be produced to change the way people understand and appropriate urban space. The study consists on a geoethnographic approach to music and dance performances in Largo do Chiado, Lisbon. I show how these different artistic practices, by producing sonic first impressions, alter the way individuals perceive urban space, and consequently, how individuals appropriate and contribute toward the formation of territories in urban space. In Study#3, I expand the phenomenology of the experience of urban sound by turning into the issue of soundmaking. The objective of this study is to understand the interaction between soundmaking and the situational relations between the individual and the environment, both in terms of the personal or collective cognitive and emotional flows, and in terms of the ethico-political content. On the other hand, Study#4 addresses the consequences of the phenomenology of everyday soundmaking by exploring how it is used to generate worlds and territories in urban space. It consists on a geoethnographic study of street football practices in Quinta da Piedade, Vila Franca de Xira, which explores how soundmaking in urban space is employed by young people to generate micro-worlds and territories. The findings of this research project contribute toward a deeper understanding of the act of listening in everyday life, and open new routes for research by conceptualising the nuances of everyday soundmaking

Identificação das cineases reguladoras da VDAC1 mitocondrial das leveduras

O canal aniónico dependente de voltagem (VDAC) é um canal tipo poro que atravessa a membrana externa da mitocôndria. O VDAC tem um papel essencial no metabolismo mitocondrial, mediando a troca de metabolitos essenciais para a respiração, produção de energia e crescimento celular. Em mamíferos, a probabilidade de abertura do canal VDAC pode ser regulada por modificações pós-traducionais como a fosforilação. Nas leveduras, o papel da fosforilação na fisiologia da VDAC1/Por1p e as cinases reguladoras são ainda desconhecidos. Deste modo, o objetivo deste estudo incide sobre a identificação de cinases reguladoras do Por1p, e a avaliação do seu papel na função mitocondrial e na fisiologia celular. Para identificar as cinases reguladoras, mutantes deficientes em 15 cinases (selecionadas de acordo com a função ou localização mitocondrial) foram avaliados em relação ao ponto isoelétrico (pI) do Por1p, através de um 2D SDS-PAGE seguido da imunodeteção do Por1p. Dois mutantes deficientes nas cinases Hog1p e Rim15p, apresentaram uma alteração no pI do Por1p, compatível com a falta de fosforilação, sugerindo que estas cinases poderão ser potenciais reguladores do Por1p. Para reforçar estes resultados, alguns fenótipos foram analisados, tais como o crescimento, consumo de oxigénio, indução de autofagia/mitofagia, resistência ao calor ou stress oxidativo, para avaliar possíveis interações genéticas entre o POR1 e a cinases identificadas, indicativo de uma relação funcional. Foi observado que a ausência de HOG1 interfere com o crescimento do por1Δ em condições fermentativas, com a indução de mitofagia e resistência ao stress oxidativo. Na ausência de RIM15, o crescimento em condições fermentativas, consumo de oxigénio, o fluxo e a indução autofágica e a indução mitofágica são afectados no mutante por1Δ. Estes resultados apoiam a hipótese das cinases Hog1p e Rim15p serem reguladoras do Por1p, sendo que mais estudos serão necessários para confirmar se esta esta regulação é directa. A identificação das primeiras cinases reguladoras do Por1p será um importante avanço no conhecimento da regulação do Por1p/função mitocondrial por vias de sinalização metabólica.The voltage-dependent anion channel (VDAC) is a conserved porin ion channel located on the outer mitochondrial membrane. VDAC plays an essential role in mitochondrial metabolism as it mediates the exchange of metabolites essential for respiration, energy production and cell growth. In mammalian cells VDAC opening probability can be regulated by posttranslational modifications such as phosphorylation. In yeast, the role of phosphorylation in VDAC/Por1p physiology and the regulatory kinases are still unknown. Therefore, the focus of the present study is to identify Por1p regulatory kinases, and evaluate its impact on mitochondrial function and cellular physiology. To identify Por1p regulatory kinases, 15 kinase-deleted mutants (selected based on kinase function or mitochondrial location) were screened for alterations in Por1p isoelectric point (pI), by 2D SDS-PAGE followed by immunoblot using an antibody against Por1p. Two strains among these, lacking Hog1p and Rim15p, exhibited a shift in Por1p pI compatible with lack of phosphorylation, suggesting these kinases may be Por1p regulators. To reinforce these result, several phenotypes such as growth, oxygen consumption, autophagy/mitophagy induction, resistance to heat or oxidative stress, were evaluated to assess genetic interactions between POR1 and the identified kinases, indicative of a functional relationship. It was observed that absence of HOG1 interferes with por1Δ growth in fermentative conditions, mitophagy induction and oxidative stress resistance. Absence of RIM15 interferes with por1Δ growth in fermentative conditions, mitochondrial oxygen consumption, autophagy flux and induction and mitophagy induction. These results support Hog1p and Rim15p as Por1p regulators, but future work will be needed to confirm them are direct regulators of Por1p phosphorylation. Identification of the first Por1p regulatory kinases in yeast will be an important advance on the understanding of the regulation of Por1p/mitochondrial function by metabolic signalling pathways.Mestrado em Biologia Molecular e Celula

An Approach to the Soundscapes of Urban Vacant Lands in Lisbon

In this paper, we will present preliminary results of our ongoing study on the soundscapes of vacant lands in Lisbon Eastern Zone (LEZ). Our methodology comprised two stages. Firstly, all the vacant lands of Lisbon municipality were identified and georeferenced using remote sensing methods and high-resolution aerial photography. In the second stage, a field survey with the purpose of characterising the morphology, vegetation, and animal and human occupation of the vacant lands was conducted, along with field recordings of their soundscapes. The results of our study include the classification of vacant lands and of their soundscapes. We argue that listening to the sounds of urban vacant lands defies traditional notions of the urban soundscape as dominated by anthrophonies.info:eu-repo/semantics/publishedVersio

On the Extension of Positive Definite Kernels to Topological Algebras

We define an extension of operator-valued positive definite functions from the real or complex setting to topological algebras and describe their associated reproducing kernel spaces. The case of entire functions is of special interest, and we give a precise meaning to some power series expansions of analytic functions that appears in many algebras

A geopoetic exploration of the Matinha vacant land, Lisbon

Our purpose in this communication is to present an exploration of the Matinha vacant land in Lisbon. Initially a sonic exploration, this endeavour would turn to the figure of the natural cyborg, an almost silent formation that thrives in the site, in the form of vegetal-technological hybrids.N/