388 research outputs found
Spatio-temporal sine-Wiener bounded noise and its effect on Ginzburg–Landau model
No full textn this work we introduce a spatio-temporal bounded noise derived by the sine-Wiener noise and by the spatially colored unbounded noise proposed by García-Ojalvo, Sancho, and Ramírez-Piscina (GSR noise). We characterize the behavior of the equilibrium distribution of this novel noise by showing its dependence on both the temporal and the spatial autocorrelation lengths. In particular, we show that the distribution experiences a stochastic transition from bimodality to trimodality.
Then, we employ the noise here defined to study the emergence of phase transitions in the real Ginzburg–Landau model. Various phenomena are evidenced by means of numerical simulations, among which reentrant transitions, as well as differences in the response of the system to “equivalent” GSR additive noise perturbations
Spatiotemporal bounded noises and transitions induced by them in solutions of the real Ginzburg-Landau model
No full textIn this work, we introduce two spatiotemporal colored bounded noises, based on the zero-dimensional Cai-Lin and Tsallis-Borland noises. Then we study and characterize the dependence of the defined stochastic processes on both a temporal correlation parameter τ and a spatial coupling parameter λ. In particular, we found that varying λ may induce a transition of the distribution of the noise from bimodality to unimodality. With the aim of investigating the role played by bounded noises in nonlinear dynamical systems, we analyze the behavior of the real Ginzburg-Landau time-varying model additively perturbed by such noises. The observed phase transition phenomenology is quite different from that observed when the perturbations are unbounded. In particular, we observed an inverse order-to-disorder transition and a reentrant transition, with dependence on the specific type of bounded noise
Cellular polarization: Interaction between extrinsic bounded noises and the wave-pinning mechanism
No full textCell polarization (cued or uncued) is a fundamental mechanism in cell biology. As an alternative to the classical Turing bifurcation, it has been proposed that the onset of cell polarity might arise by means of the well-known phenomenon of wave-pinning [ Gamba et al. Proc. Natl. Acad. Sci. USA 102 16927 (2005)]. A particularly simple and elegant deterministic model of cell polarization based on the wave-pinning mechanism has been proposed by Edelstein-Keshet and coworkers [ Biophys. J. 94 3684 (2008)]. This model consists of a small biomolecular network where an active membrane-bound factor interconverts into its inactive form that freely diffuses in the cell cytosol. However, biomolecular networks do communicate with other networks as well as with the external world. Thus, their dynamics must be considered as perturbed by extrinsic noises. These noises may have both a spatial and a temporal correlation, and in any case they must be bounded to preserve the biological meaningfulness of the perturbed parameters. Here we numerically show that the inclusion of external spatiotemporal bounded parametric perturbations in the above wave-pinning-based model of cellular polarization may sometimes destroy the polarized state. The polarization loss depends on both the extent of temporal and spatial correlations and on the kind of noise employed. For example, an increase of the spatial correlation of the noise induces an increase of the probability of cell polarization. However, if the noise is spatially homogeneous then the polarization is lost in the majority of cases. These phenomena are independent of the type of noise. Conversely, an increase of the temporal autocorrelation of the noise induces an effect that depends on the model of noise
The phlebological surgery in elderly patients
No full textThe pathogenesis of the lower limbs varicose veins in the elderly patients is the same one as in the juvenile and adult age. What changes is the severity of the clinical picture, because the disease is a chronic pathology and it is aggravated with the passing of the years in absence of prophylaxis and missed or inadequate therapy.
Equally the surgical operations on the superficial venous system of the elderly patients from a technical point of view are the same that are practiced in other ages of life. What changes is the anaesthesiological risk, which is increased, because other chronic pathologies are frequently associated with the old ones.
Currently both the use of techniques of peripheral anesthesia, as the blocks of the lower limbs nervous trunks, and the introduction of poor toxic anesthetics for the heart in therapeutical practice allow in an inci¬sive way to submit elderly people to surgical procedures.
Above all the out-patient hemodynamic surgery of the superficial chronic venous insufficiency, which requires a careful and meticulous instrumental investigation aimed surgical gestures, but simple, effective, of brief duration, has convinced many surgeons of the possibility to operate on the varicose patients of a more and more advance age.
On the other hand the rapid postoperative mobiliza¬tion of those sick, in absence of immediate complica¬tions, means that they can be discharged from the hospital on the same day of the operation.
This undoubtedly involves positive reflexes on the sanitary expense and it increases at the same time the compliance in terms of motivation and acceptance of the proposed procedure.
The elderly patient, perhaps more than the younger adult, once informed of the new anaesthesiological and surgical techniques, gladly gives his consent to the inter¬vention, pleased to return to his own house and tquickly return to his daily occupations.
How much I dictate you is translated in our experi¬ence, that is carried out near the Phlebological Center of the Siena University, in a progressive increase in the last 5 years both in absolute terms (223) and percen¬tages (12%) of the number of subjects older than sixty¬five years old that have been submitted to surgical operations for the venous disease.
Of all 223 patients, males are 68 and females are 155; 144of them have an age between 66 and 70 years, 73 belonging to the eighty years of life and 6 subject to the ninty. All patients have been operated in Day Hospi¬tal admission. No mortality has been found. Local post-operative complications was encountered in 1,8% of the cases
Chronic Venous Ulceration of the lower limbs and Thrombosis.
No full textChronic venous ulceration is a major complication of chronic venous disorder with important implications in terms of mor- bidity and social expenditure. Venous thrombosis and throm- bophilia are widespread conditions, often associated with venous ulcers of the lower limbs. This link has not yet been widely described in the literature and aim of this work was to analyze the relationship between these two conditions review- ing the current literature. PubMed, Scopus and ScienceDirect databases were searched for articles using the terms: throm- bophilia, venous ulceration, chronic venous disorders and the significant full text were downloaded and analyzed. From the literature review, a description of the most common throm- bofilic abnormalities found in literature and the relation- ship with CVU was given. Conditions such as antithrombin deficiency, protein C deficiency, protein S deficiency, factor V Leiden, hyperhomocystinaemia, prothrombin G20210A mutation, antiphospholipid antibodies, elevated factor VIII levels, elevated factor XI levels, plasminogen activator inhibi- tor type 1 mutations, cancer, obesity, pregnancy and trauma through current literature were statistically linked to the presence of chronic venous ulceration. The main conclusion to be drawn from the available literature is that patients with chronic venous ulceration of the lower limbs appear to have a prevalence of thrombophilia and/or thromboembolic events that is much higher than in the general populatio
A haemodynamic model of the venous network of the lower limbs
No full textThe pathologies of the venous system are characterized by a relevant socioeconomic impact in western countries. To this regard, the blood flow correction allows to solve the most important venous pathologies. In these cases, in order to guarantee the restoration of normal blood flow by means of proper modifications of the venous network, the correct planning of haemodynamics surgical operations is needed; such planning in turn depends on the right analysis of the possible consequences of flow modification. To this end, a mathematical model, that allows to precisely study the physiological and pathological behaviour of the venous network of the lower limbs, has been developed. The final goal is to use this model as an instrument helpful to plan surgical operations and give guidelines for the design and the test of new artificial devices. As for the modelling processing, a lumped parameters model has been derived with a resolution which allows to take into account the anatomic characteristics of the venous system
Potere di revoca del mandato da parte del corpo elettorale in caso di disapprovazione dell’operato degli amministratori: Il Recall.
No full textLa opportunità d’ individuare oggi degli strumenti che consentano di garantire un controllo sull’operato degli eletti si palesa in modo drammatico in particolare nei sistemi a democrazia maggioritaria. In alcune nazioni a democrazia matura si è sviluppato un fisiologico turn-over dei governanti, con un sistema che premia la buona amministrazione e sanziona gli amministratori, che in qualche misura non abbiano dato buona prova di curarsi della res pubblica. Il turn-over pur essendo un ottimo strumento sanzionatorio, non può, però, essere l’unico a tutelare la polis ed infatti tanto gli Stati Uniti d’America, il Canada e la Svizzera quanto il Venezuela e la Cina hanno introdotto un meccanismo – il recall- che attribuisce all’elettorato la facoltà di rimuovere, prima della scadenza del mandato, chi aveva eletto. Questo strumento ben si adatta tanto a forme di governo parlamentari quanto a quelle presidenziali, non rilevando la maturità ovvero la debolezza democratica dei regimi che lo prevedono. Inoltre, generalmente, la revoca si è rivelata strumento neutrale rispetto all’appartenenza partititica, suscitando un’elevata partecipazione alla consultazione. La revoca ha altresì dimostrato d’essere valido strumento di controllo e verifica dell’operato degli amministratori ed al contempo di stimolo ad una fattiva partecipazione dei cittadini alla gestione della res pubblica. La presenza di elevati ed aggravati quorum partecipativi garantisce l’eletto da plebiscitarie giustizie sommarie ed appaga il desiderio partecipativo dei cittadini, consapevoli di avere un’alta possibilità di successo. La fruibilità della procedura di revoca da parte dei cittadini produce nell’eletto un’elevata attenzione verso le aspettative degli elettori, di cui è pro tempore servitore con ampi poteri. Da ultimo si rileva come questo strumento abbia limitato ampiamente l’influenza delle lobbies, istigando l’eletto ad interessarsi delle aspettative di tutti coloro che lo hanno espresso e non solo dei finanziatori più o meno occulti della campagna elettorale. La pubblicazione dei dati della ricerca vuole avere la presunzione di far scaturire un dibattito sull’esportabilità dello strumento nel nuovo quadro ordinamentale delle regioni italiane. Il governo delle regioni, infatti, ha assunto, con la riforma del Titolo V, una forma presidenziale; la legge elettorale poi, pur non introducendo il maggioritario puro, ha certamente favorito la diminuzione dell’ intermediazione dei partiti, attribuendo nel contempo la responsabilità diretta degli eletti nella amministrazione della res pubblica. Elementi questi che non solo consentono la comparazione ma autorizzano, a giudizio di chi scrive, uno studio della possibilità di introdurre il recall in Italia. Un ulteriore elemento, che incoraggia a valutare positivamente l’eventuale introduzione di un tale strumento di controllo (nonostante una forte resistenza al trapianto giuridico), è l’averne rilevata la presenza anche in Canada, stato che s’ ispira alla forma parlamentare pura del modello di Westminster e, pertanto, più vicina per esperienza e tradizione all’ Italia. Pur confermando una ritrosia a trapianti costituzionali, sembra fondata la persuasione che l’introduzione di una procedura di revoca- analoga al recall - possa produrre nell’attività amministrativa degli enti territoriali nazionali minori altrettanti benefici risultati
Nucleic acids delivering nucleic acids.
No full textNucleic acid therapeutics, including siRNAs, miRNAs/antimiRs, gRNAs and ASO, represent innovative and highly promising molecules for the safe treatment of a wide range of pathologies. The efficiency of systemic treatments is impeded by 1) the need to overcome physical and functional barriers in the organism, and 2) to accumulate in the intracellular active site at therapeutic concentrations. Although oligonucleotides either as modified naked molecules or complexed with delivery carriers have revealed to be effectively delivered to the affected target cells, this is restricted to topic treatments or to a few highly vascularized tissues. Therefore, the development of effective strategies for therapeutic nucleic acid selective delivery to target tissues is of primary importance in order to reduce the occurrence of undesired effects on non-target healthy tissues and to permit their translation to clinic. Due to their high affinity for specific ligands, high tissue penetration and chemical flexibility, short single-stranded nucleic acid aptamers are emerging as very attractive carriers for various therapeutic oligonucleotides. Yet, different aptamer-based bioconjugates, able to provide accumulation into target tissues, as well as efficient processing of therapeutic oligonucleotides, have been developed. In this respect, nucleic acid aptamer-mediated delivery strategies represent a powerful approach able to increase the therapeutic efficacy also highly reducing the overall toxicity. In this review, we will summarize recent progress in the field and discuss achieved objectives and optimization of aptamers as delivery carriers of short oligonucleotides
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