323,559 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
Diffusive author(s), cohesive author: Analysis of S/N (1994)
No full textThis study indicates the ways in which various aspects of the author(s) are brought forth in Dumb type’s performance art, the S/N production. Previous research has suggested a non-hierarchical organization of Dumb type and the absence of a “privileged author” in Dumb type’s collaborative work, S/N. However, the results that I have investigated from member’s interviews on the creative process of S/N along with my analysis of the recorded images of S/N, indicate a different aspect of the author(s). First, S/N was created through, so to speak, the collective ideas of the members of Dumb type. Further, S/N has at least nine quotations from previous performances, installations, and printed writings, besides the work-in-progress technique. Explicating one of the “author functions” as given by Michel Foucault, each text has plural subjects of the author. However, it has been revealed from members’ interviews that Teiji Furuhashi had a decision-making role in selecting the members’ ideas within the performance. Since then, S/N has had plural subjects of creation; however, Furuhashi is one of the subjects of creation along with the “privileged author.” S/N has plural authors (diffusive authors) yet at the same time, it has a “privileged author,” Teiji Furuhashi (cohesive author)
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
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Role of Intercellular Coupling on Chromatin Changes Transcriptional Activity and Meiotic Competence Acquisition During Bovine Oocyte Growth In Vitro
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