154 research outputs found
Computing hierarchical transition graphs of asynchronous genetic regulatory networks
No full textIn the field of theoretical biology the study of the dynamics of the so-called gene regulatory networks is useful to follow the relationship between the expression of a gene and its dynamic regulatory effect on the cell fate. To date, most of the models developed for this purpose, applies the synchronous update schedule while reality is far from being so. On the other hand, the more realistic asynchronous update requires to compute all possible updates at each single instant, thus bearing a much greater computational load. In the present work, we describe a novel method that addresses the problem of efficiently exploring the dynamics of a gene regulatory network with the asynchronous update
Essentiality is an emergent property of metabolic network wiring
No full textThe topological bases of essentiality in the yeast metabolic network from the perspective of double mutations are the subject of this study. A strong relationship between essentiality and the ‘missing alternative’ topological property is shown in terms of the presence of multiple genes synthesizing the same enzyme, supplementary enzymes participating in the same metabolic reaction, and availability of other pathways in the graph connecting the separated nodes after the knockouts. We demonstrate that the ‘missing alternative’ paradigm is sufficient to explain the generation of essentiality for double mutations in which each single deleted element is non-essential
Functional essentiality from topology features in metabolic networks: A case study in yeast
No full textThe relation between the position of mutations in Saccharomyces cerevisiae metabolic network and their lethality is the subject of this work. We represent the topology of the network by a directed graph: nodes are metabolites and arcs represent the reactions; a mutation corresponds to the removal of all the arcs referring to the deleted enzyme. Using publicly available knock-out data, we show that lethality corresponds to the lack of alternative paths in the perturbed network linking the nodes affected by the enzyme deletion. Such feature is at the basis of the recently recognized importance of 'marginal' arcs of metabolic networks. (c) 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved
Compliance mechanisms under selected multilateral environmental agreements, (Co-author Ulrich Beyerlin)
No full textThe Figure of the Limit: Metalepsis
No full textIn 1972, Gérard Genette introduced in narratology the figure of metalepsis, that is «any intrusion by the extradiegetic narrator or narratee into the diegetic universe (or by diegetic characters into a metadiegetic universe, etc.), or the inverse». In other words, metalepsis is a transgression of narrative levels, a perturbation of hierarchy that raises the question of the porosity of boundaries between diegetic and metadiegetic, author and reader, fact and fiction.
In my presentation, I will show how this phenomenon is ubiquitous nowadays, and how it is settled both in highbrow and lowbrow cultural representations across various media.
Furthermore, I wish I can discuss the role of metalepsis in poetics: in my opinion, it is possible to relate this device with the history of the novel. In XVIII and XIX centuries authorial narrators made extensive use of rhetoric metalepsis for humoristic purposes (such as playing with the story-time and the discourse-time) or to exhibit their authority (through the manipulation of different threads of the narration). With Naturalism and Modernism metalepsis disappeared, according to the poetic of impersonality: authors stopped being intrusive and eclipsed behind their characters. The golden era of the figure came in the temper of Postmodernism, where ontological metalepsis flourished and the public got used to author and reader literary entering the fiction or characters exiting from it and chitchatting with their creators
Andrea e gli argentieri Memingher in Sicilia
No full textAndrea Memingher è una tra le più enigmatiche figure di argentieri attivi a Palermo nella seconda metà del XVII secolo. Si può ritenere che la famiglia avesse origini nordiche e che, dopo un passaggio a Napoli, si stabilisse definitivamente a Palermo, inserendosi nella maestranza degli orafi e argentieri della città, probabilmente grazie ad un matrimonio con una figlia o una sorella o una vedova di un membro palermitano della maestranza. La presenza di Paolo Memingher nel capoluogo siciliano è attestata già nel 1660, due anni prima della data di inizio della sua attività, protrattasi fino al 1678. Il più importante esponente della famiglia fu Andrea, figlio di Paolo, il quale dovette la sua fama, al di là dell’abilità e dell’origine straniera, anche al suo status di padre gesuita. Il saggio studia la figura dell’artista, attivo dal 1670 al 1738, anno di morte, autore di un consistente corpus di opere giunto fino a noi, e dei congiunti che operarono nel medesimo contesto.Andrea Memingher is one of the most enigmatic figures of silversmiths active in Palermo in the second half of the seventeenth century. It can be assumed that the family had Nordic origins and that, after a passage to Naples, it settled permanently in Palermo, entering the mastery of the goldsmiths and silversmiths of the city, probably thanks to a marriage with a daughter or a sister or a widow of a Palermitan member of the mastery. The presence of Paolo Memingher in the Sicilian capital is attested as early as 1660, two years before the start of his activity, which lasted until 1678. The most important exponent of the family was Andrea, son of Paolo, who owed his fame, beyond the ability and foreign origin, even to his status as a Jesuit father. The essay studies the figure of the artist, active since 1670 to 1738, the year of his death, author of a substantial body of works that has come to us, and of the relatives who worked in the same context
Anesthetic Management during Cesarean Section in English Bulldogs
No full textThe authors describe their experience with the management of the perioperative period, general anesthesia and the
postoperative period in English bulldogs undergoing elective cesarean section and its effect on the neonates. The anesthetist for
animals undergoing cesarean operation must be aware of any special needs, not only of the patient undergoing surgery, but also of
the neonates. Anesthetic drugs administered to the pregnant patient will readily cross the placenta and affect them, with the exception
of local anesthetics. Pregnant female patients are at increased anesthetic risk due to pregnancy-associated physiological alterations,
such as altered pulmonary function. The anesthetist is often called to perform anesthesia on brachycephalic dogs for an elective
cesarean section. Due to their conformation, these animals may have one or more anatomical abnormalities of the upper airways,
which compromise the ability to ventilate adequately. The induction and recovery phases of anesthesia can be extremely dangerous
in these patients, but the maintenance phase is generally fairly straightforward because the airways are controlled during maintenance.
In addition, vagal tone is frequently high and this can contribute towards significant bradycardia and further airway narrowing. All
these reasons make general anesthesia in brachycephalic dogs undergoing cesarean section rather complicated
Collective behavior in gene regulation: Post-transcriptional regulation and the temporal compartmentalization of cellular cycles
No full textSelf-sustained oscillations are perhaps the most studied objects in science. The accomplishment of such a task reliably and accurately requires the presence of specific control mechanisms to face the presence of variable and largely unpredictable environmental stimuli and noise. Self-sustained oscillations of transcript abundance are, in fact, widespread and are not limited to the reproductive cycle but are also observed during circadian rhythms, metabolic cycles, developmental cycles and so on. To date, much of the literature has focused on the transcriptional machinery underlying control of the basic timing of transcript abundance. However, mRNA abundance is known to be regulated at the post-transcriptional level also and the relative contribution of the two mechanisms to gene-expression programmes is currently a major challenge in molecular biology. Here, we review recent results showing the relevance of the post-transcriptional regulation layer and present a statistical reanalysis of the yeast metabolic cycle using publicly available gene-expression and RNA-binding data. Taken together, the recent theoretical and experimental developments reviewed and the results of our reanalysis strongly indicate that regulation of mRNA stability is a widespread, phase-specific and finely tuned mechanism for the multi-layer control of gene expression needed to achieve high flexibility and adaptability to external and internal signals
ETICHETTE INTELLIGENTI PER LA RILEVAZIONE VISIVA DEL DETERIORAMENTO DEI PRODOTTI ALIMENTARI
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