767 research outputs found
Il senso educativo dei nonni nei vissuti dei preadolescenti immigrati.
No full textLa presente indagine, svolta nei confronti di 33 studenti preadolescenti immigrati, intende:
– rilevare le percezioni e identificare gli stereotipi dei preadolescenti immigrati nei confronti della vecchiaia;
– rilevare le differenze delle rappresentazioni dei nonni tra i preadolescenti immigrati distinti per polarità di genere, di accudimento e di arrivo nel nostro Paese;
– ricavare le strutture concettuali portanti relative alle funzioni
educative dei nonni e alla “perdita educativa” vissuta dai ragazzi con l’allontanamento dai nonni che li avevano allevati.
Sono state isolate dodici funzioni educative che i preadolescenti immigrati attribuiscono ai nonni: proteggere dai genitori, condividere, supplire la mancanza dei genitori, conciliare e concedere,
prendersi cura, aiutare, raccontare, consigliare, insegnare, star bene facendo insieme, preparare da mangiare, erogare soldi e regali.
Infine, si analzza il senso dell’assenza educativa: la fortissima carica affettiva che accompagna
la sensazione di abbandono, il senso di solitudine e di
vuoto interiore impatta fortemente in soggetti a fragile identità
Super-Linear Time-Memory Trade-Offs for Symmetric Encryption
No full textWe build symmetric encryption schemes from a pseudorandom
function/permutation with domain size which have very high
security -- in terms of the amount of messages they can securely
encrypt -- assuming the adversary has bits of memory. We aim
to minimize the number of calls we make to the underlying
primitive to achieve a certain , or equivalently, to maximize the
achievable for a given . We target in
particular , in contrast to recent works (Jaeger and
Tessaro, EUROCRYPT \u2719; Dinur, EUROCRYPT \u2720) which aim to beat the
birthday barrier with one call when .
Our first result gives new and explicit bounds for the
Sample-then-Extract paradigm by Tessaro and Thiruvengadam (TCC
\u2718). We show instantiations for which .
If , Thiruvengadam and Tessaro\u27s weaker bounds
only guarantee when . In contrast, here,
we show this is true already for .
We also consider a scheme by Bellare, Goldreich and Krawczyk (CRYPTO
\u2799) which evaluates the primitive on independent random
strings, and masks the message with the XOR of the outputs. Here, we
show , using new combinatorial bounds
on the list-decodability of XOR codes which are of independent
interest. We also study best-possible attacks against this
construction
Trattamento antivirale in pazienti portatoricronici di epatite C e transaminasemianormale a lungo termine: risultati preliminaridi uno studio pilota
No full textOBIETTIVI: valutare l’efficacia del PEG-IFNa-2a + ribavirina in una coorte
di pazienti HCV positivi con livelli di ALT persistentemente normali in
accordo con le nuove linee guida internazionali.MATERIALI: sono stati inclusi nello studio un gruppo di soggetti con almeno
3 determinazioni di ALT normali in un periodo superiore a 12 mesi. Tali
soggetti sono stati trattati con PEG-IFNa-2a 180mg/settimana + ribavirina
800 mg/die per 24 settimane se appartenenti ai genotipi 2 e 3, oppure per
48 settimane se appartenenti ai genotipi 1 e 4.
RIASSUNTO: sono stati arruolati 206 pazienti (48 M, 158 F). I soggetti
maschi, rispetto alle femmine, presentavano una differenza significativa
con valori più alti di BMI, ALT, GGT, carica virale e grading/staging della
fibrosi alla biopsia epatica. Il genotipo 2 è risultato il più rappresentato,
rispettivamente, nel 65,5% delle femmine e nel 55,2% dei maschi, mentre
i genotipi 1 e 4 erano presenti nel 34,5% dei soggetti. Il trattamento è stato
completato dal 95,7% (188/206) dei pazienti, mentre 18 (8,7%) hanno
interrotto il trial per le seguenti motivazioni: 3 hanno autosospeso il
trattamento, 4 sono risultati non responder, i rimanenti 11, a causa della
comparsa di effetti collaterali. I 188 pazienti che hanno concluso la terapia
sono stati seguiti con un follow-up minimo di 6 mesi in cui veniva monitorata
la carica virale con dosaggi mensili. Sono risultati non responders 11
(5,8%) pazienti, mentre 171 (90,9%) hanno risposto e mantenuto la risposta
a distanza di 6 mesi dopo la fine della terapia con una percentuale di
ricaduta, alla sospensione, del 2,9%.
CONCLUSIONI: da una preliminare analisi dei dati, emerge l’indicazione di
offrire il trattamento antivirale anche a pazienti con epatite cronica da HCV
e valori di ALT persistentemente normali
A METABOLIC-LIKE CYCLE FOR SYNTHETIC APPLICATIONS
No full textSystems Biocatalysis is a new approach consisting of organizing enzymes in vitro to generate an artificial metabolism for synthetic purposes. The interconversion of functional groups is the main objective of biocatalysis, and systems organizing a series of enzymes to achieve a multi-step reaction have been reported. The assembly of essentially the same enzymes utilized in Nature to drive the transformation of carbohydrates towards useful synthetic intermediates [1] has been referred to as an artificial metabolism. SysBiocat aims at a similar goal addressing the generalization and organization of group of enzymes (a tool-box) able to perform a series of reactions of general synthetic utility where the feasibility is connected with the obtainment of enzymes of wide substrate specificity or in a rich array of variable common catalytic functions. [2] As a demonstration of this concept, we have recently assembled a biochemical like cycle (Asp-cycle) connecting among them an unsaturated carboxylate (fumaric acid), an alpha-amino acid (L-aspartic acid), a keto acid (oxalacetic acid) and the corresponding alpha-hydroxyacid (D- or L-malic acid). [3]
In this view, the obtained cycle may be exploited by coupling it with synthetically relevant reactions which are driven to completion thanks to one or more irreversible steps in the reaction sequence.
____
[1] W.D. Fessner, C. Walter, “Artificial metabolism”, Angew Chem Int Ed, 1992, 31, p. 614
[2] U. T. Bornscheuer, G. W. Huisman, R. J. Kazlauskas, S. Lutz, J. C. Moore, K. Robins, “Engineering The Third Wave Of Biocatalysis”, Nature, 2012, 485, p. 185
[3] D. Tessaro, L. Pollegioni, L. Piubelli, P. D’Arrigo, S. Servi, “Systems Biocatalysis: An Artificial Metabolism for Interconversion of Functional Groups”, ACS Catalysis, 2015, 5, p. 160
Multistep enzyme catalyzed reactions for unnatural amino acids.
No full textThe use of unnatural amino acids, particularly synthetic α-amino acids, for modern drug discovery research requires the availability of enantiomerically pure isomers. Starting from a racemate, one single enantiomer can be obtained using a deracemization process. The two more common strategies of deracemization are those obtained by stereoinversion and by dynamic kinetic resolution. Both techniques will be here described using as a substrate the D,L-3-(2-naphthyl)-alanine, a non-natural amino acid: the first one employing a multi-enzymatic redox system, the second one combining an hydrolytic enzyme together with a base-catalyzed substrate racemization. In both cases, the final product, L-3-(2-naphthyl)alanine, is recovered with good yield and excellent enantiomeric excess
Layout Graphs, Random Walks and the t-wise Independence of SPN Block Ciphers
No full textWe continue the study of -wise independence of substitution-permutation networks (SPNs) initiated by the recent work of Liu, Tessaro, and Vaikuntanathan (CRYPTO 2021).
Our key technical result shows that when the S-boxes are randomly and independently chosen and kept secret, an -round SPN with input length is -close to -wise independent within rounds for any almost as large as . Here, is the input length of the S-box and we assume that the underlying mixing achieves maximum branch number.
We also analyze the special case of AES parameters (with random S-boxes), and show it is -close to pairwise independent in rounds.
Central to our result is the analysis of a random walk on what we call the layout graph, a combinatorial abstraction that captures equality and inequality constraints among multiple SPN evaluations.
We use our technical result to show concrete security bounds for SPNs with actual block cipher parameters and small-input -boxes. (This is in contrast to the large body of results on ideal-model analyses of SPNs.) For example, for the censored-AES block cipher, namely AES with most of the mixing layers removed, we show that 192 rounds suffice to attain -closeness to pairwise independence. The prior such result for AES (Liu, Tessaro and Vaikuntanathan, CRYPTO 2021) required more than 9000 rounds
Role of Intercellular Coupling on Chromatin Changes Transcriptional Activity and Meiotic Competence Acquisition During Bovine Oocyte Growth In Vitro
No full textApplication of Transaminases in a Disperse System for the Bioamination of Hydrophobic Substrates
No full textThe challenging bioamination of hydrophobic substrates has been attained through the employment of a disperse system consisting of a combination of a low polarity solvent (e. g. isooctane or methyl-tert-butylether), a non-ionic surfactant and a minimal amount of water. In these conditions, amine transaminases (ATA) were shown to efficiently carry out the reductive amination of variously substituted cyclohexanones, providing good conversions often coupled with a superior stereoselectivity if compared with the corresponding chemical reductive amination. An array of synthetically useful 4-substituted aminocyclohexanes was consequentially synthesized through biocatalysis, analyzed and stereochemically characterized. (Figure presented.)
Regional and age-related differences in mRNA composition of intracellular Ca2+-release channels of rat cardiac myocytes.
No full textWe investigated the mRNA distribution of three different ryanodine receptors (RyR) and of the intracellular Ca2+-release channel/inositol 1,4,5-trisphosphate receptor (IP3R) type 1 in the rat heart during development and aging. In situ hybridization analysis shows that RyR1 mRNA is never expressed in the heart at any of the stages examined; RyR2 mRNA is; detectable in cardiomyocytes in the early embryonic stages, whereas RyR3 mRNA accumulates in cardiomyocytes around birth. IP3R mRNA appears al first in the primitive atrium at embryonic day 11 and in subsequent stages it is detectable also in a minor population of ventricular myocytes, which presumably correspond to conduction system precursors. In the adult heart, no apparent difference in hybridization signal intensity is observed between atrial and ventricular working myocytes either with RyR2, RyR3 or IP3R cRNA probes, except for myocytes of the heart conduction system, which differ from working myocytes in the intensity of the hybridization signals for each probe. Additional differences are detected in the senescent heart with the IP3R cRNA probe, which hybridizes with atrial myocytes stronger than with ventricular ones. RNase protection analysis confirms the temporal differences in RyRZ and RyR3 transcript accumulation observed during heart development and reveals a significant increase of IP3R mRNA in the atrial myocardium during aging. Thus, the composition of intracellular Ca2+-release channel mRNAs of the rat heart shows temporal and regional variations: such changes might reflect important differences in transcriptional regulation of these genes among myocytes
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