1,721,009 research outputs found
La città nascosta. il cimitero della Chacarita
No full textIl saggio propone una riflessione su una delle prime opere dell’architetto italo/argentino Clorindo Testa.
Come in molti altri cimiteri del mondo, anche quello della Chacarita, sito nella grande metropoli di Buenos Aires, può essere interpretato come una vera città nella città.
Ma è addentrandosi in questo mondo parallelo che la riflessione tra vita e morte prende forma parlando attraverso il linguaggio dell’architettura. Dall’ingresso principale, una sedimentazione di epoche e stili ci accompagna al cuore geografico del cimitero, dove la costruzione del Sexto Panteón, datata 1958, non è che la prima tappa di un cammino senza fine, dove giochi di luce e labirintici corridoi animano lo spazio “eterno” nel sottosuolo.In this essay a characteristic thought about one of the first Clorindo Testa’s work is going to be discussed.
He was one of the most important Italo Argentinian architects of the XX century.
The cemetery of Chacarita, like many other cemeteries sited in the huge Metropolis of Buenos Aires, will be interpreted as a real “city in the city”.
Only venturing into this parallel world, this thought about what is in between life and death shapes up through the language of Architecture.
From the main entrance a layering of different periods and styles accompanies us to the heart of the cemetery, where the construction of the Sexto Panteón, dated 1958, takes place. This is just the first stop of an endless path where light effects and corridors labyrinthically animate the “eternal” space of the underground
Minimal value of the maximal dose fraction in the optimization of the radiotherapy scheduling
No full textInsulin signaling network: mathematical modeling and parameter estimation from experimental data
Full text linkThe insulin signaling network (ISN) is an important metabolic network that, upon the insulin binding to its receptor at the cell surface, triggers the glucose uptake into the cell. The study of this mechanism within muscle cells, hepatocytes and cells of the adipose tissue is of major interest since it is crucial for understanding more clearly the factors that may induce the insulin resistance. However, the structure and the behaviour of the insulin signaling network are only partially known and the current research on this topic is
fragmented into various lines of investigation. Because of the high degree of complexity of the ISN, it is diffcult to understand, without a theoretical framework, how the network responses evidenced from the experimental data determine the cell behaviour.
In the present thesis, we proposed a detailed mathematical model of the ISN in order to investigate the factors that affect the basal concentrations and the dose-response curves (i.e., the steady state concentrations at given insulin levels) of the main components of the whole network. Our model concentrated particularly on single and double phosphorylation of Akt protein, and hypothesized the existence of a putative factor released by the small intestine that induces insulin resistance by activating the mammalian target
of rapamycin complex 2 (mTORC2) in an insulin-independent manner and possibly operating through the IGF-1 receptor. Such hypothesis is based on clinical and experimental observations.
The parameters of the ISN model were estimated from the experimental data of two skeletal muscle cell lines using a least squares approach. As the available data consisted in the equilibrium concentrations of many of the known signaling components at given values of the insulin, we derived the concentrations of the chemicals at the steady-state from the kinetic equations and then we implemented an algorithm that minimizes the distance between the model outputs and the data. For the numerical solution, we used a local optimization routine based on a derivative-free algorithm for bound constrained optimization.
The ISN model was able to adequately fit the available experimental data. The model could thus become a useful tool to generate and test hypotheses, leading to a deeper understanding of the molecular mechanisms underlying insulin resistance and, in future perspective, to find drugs able to counterbalance the effects of this disease.
Finally, as it is now widely recognized that Akt and mTOR complexes have a major role also in the regulation of cell proliferation, and then in cancer development, we combined the ISN model with a mathematical model that described the evolution of a AML (acute myeloid leukemia) cell population in order to investigate the effects of mTOR inhibitors with antitumor activity on the ISN and on the cell population response. Based on literature data of AML cell response to mTOR inhibitors with antitumor activity (the dual ATP-competitive mTOR inhibitor AZD8055), the two models provided simple relationships between the concentrations of proteins of the ISN and parameters representative of cell cycle progression and cell death
Minimum value of the maximal entry of n-dimensional vectors with constant sum of the entries and of the squared entries
No full textWe present the analytical study of a constrained non-linear optimization problem relevant to the optimization of fractionated radiotherapy protocols of length . The admissible set considered here is derived from the imposition of constraints, mandatory in radiotherapy, to guarantee that the damages caused to healthy tissues by the radiation do not exceed assigned tolerable levels. Radiation damages are evaluated by means of the well-known LQ model and, for suitable values of the normal tissue parameters, the constraints are written as a linear constraint and a quadratic constraint. In this report, we prove a property satisfied by the value of the maximal entry of vectors in the mentioned feasible region, and precisely we determine the minimal value of the maximal entry of such vectors. This result is significant for the problem of radiotherapy optimization when an upper bound is set on the size of the daily fraction doses in addition to the normal tissue constraints [3]. Indeed, the optimum of the present problem acts as a threshold with regard to the dose upper bound influencing the type of solution of the radiotherapy optimization problem
Optimal weekly scheduling in fractionated radiotherapy: effect of an upper bound on the dose fraction size
No full textThis work concerns the optimization of the dose fractionation for cancer radiotherapy schedules of the kind one fraction/day, five fractions/week, assuming a fixed overall treatment time. Constraints are set to limit the radiation damages to surrounding normal tissues, as well as the daily fraction size. The response to radiation of tumour and normal tissues is represented by the classical LQ model, including the exponential repopulation term.We provide a framework to analytically determine the optimal weekly scheme of radiation doses as a function of the tumour type, the fraction upper bound and the normal tissue parameters. For a comparison with the literature,we present some numerical examples of optimal treatment schedules for specific tumour types
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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