1,721,212 research outputs found
Riservatezza e integrità su servizi database cloud
No full textIl successo dei servizi basati su cloud è legato a garanzie di disponiibilità, scalabilità e sicurezza. Se da un lato le infrastrutture cloud soddisfano i primi due requisiti, come fornire garanzie di confidenzialità e di integrità dei dati è ancora un problema irrisolto per i servizi database cloud.
Questa tesi propone nuove architetture e protocolli per proteggere informazioni di primaria importanza che vengono memorizzate in infrastrutture gestite da fornitori di servizi cloud pubblici. Le soluzioni proposte includono la progettazione e l'integrazione di protocolli crittografici avanzati che prevengono accessi e modifiche illegittime ai dati riservati mantenendo efficienti le operazioni di recupero e di calcolo. Tutte le scelte di progetto hanno avuto lo scopo di ottenere soluzioni funzionali utilizzabili in scenari di utilizzo reali. La tesi include implementazioni, valutazioni prestazionali, modelli formali e dimostrazioni di sicurezza che mostrano la correttezza, l'efficienza e la sicurezza delle architetture, degli schemi e dei protocolli proposti.he success of the cloud-based services is related to guarantees in terms of service availability, scalability and security. While the cloud infrastructures satisfy the first two attributes, data confidentiality and integrity are still open issues in cloud database services.
This thesis proposes novel architectures and protocols to protect critical information that is placed in infrastructures managed by public cloud providers. We design and integrate advanced cryptographic protocols that prevent illegitimate access and modification of the confidential information while allowing efficient retrieval and computation operations. All design choices aim to practical solutions that can be deployed in real scenarios. This thesis includes implementation, performance evaluations, formal models and security proofs to demonstrate correctness, efficiency and security of the proposed architectures, schemes and protocols
Specific and reversible inhibition of the blunt-end joining activity of the T4 DNA ligase
No full textSpecific, complete and reversible inhibition of the
joining of blunt ended DNA duplexes catalyzed by the T4 DNA ligase can be obtained by using ATP, the enzyme cofactor, at concentrations of 5 mM and higher.
On cohesive DNA ends, 5 mM ATP, which completely inhibits blunt end ligation, brings about only a limited (8%) reduction in the level of joining obtainable under optimal ATP concentra tion (0,5 mM or lower). A similar but less drastic uncoupling of the two kinds of joining can b$+achieved at lower ATP con_ centration(2,5mM)using1mMMg .
The joining of DNA blunt ends can also be inhibited almost completely by 10 mM spermidine, without noticeable effect on the joining of cohesive termini
Temperature dependance in the joining of flush and cohesive ends produced by restriction endonucleases
No full textThe temperature dependence of the T4 DNA ligase-catalyzed joining of plasmid DNA linearized by the action of HaeIII, EcoRI and PstI restriction endonucleases has been investigated by electron microscopy analysis. The extent of joining is maxi mal at 40 and decreases with increasing temperatures following sigmoid - like curves.
The temperature at which 50% of the maximal reaction is still observable increases going from DNA termini without single-stranded overlaps (produced by HaeIII) to termini with four nucleotides overlap, composed only by two A and two T
(produced by EcoRI) to termini with four nucleotide overlap, composed by A, T, G and C (produced by PstI)
SISTEMA PER LA RILEVAZIONE E LA QUANTIFICAZIONE DI DNA ESOGENO DI ORIGINE ANIMALE IN FARINE ALIMENTARI DESTINATE AL SETTORE ZOOTECNICO
No full textnumero domanda: M12004A000991
data deposito: 18 maggio 200
Condensation and topological phase transitions in a dynamical network model with rewiring of the links
Full text linkGrowing network models with both heterogeneity of the nodes and topological constraints can give rise to a rich phase structure. We present a simple model based on preferential attachment with rewiring of the links. Rewiring probabilities are modulated by the negative fitness of the nodes and by the constraint for the network to be a simple graph. At low temperatures and high rewiring rates, this constraint induces a Bose-Einstein condensation of paths of length 2, i.e., a new phase transition with an extended condensate of links. The phase space of the model includes further transitions in the size of the connected component and the degeneracy of the network. © 2014 American Physical Society
Molecular analysis of the Fragile Histidine TRiad (FHIT) tumor suppressor gene in vesical tumors of cattle with Chronic Enzootic Hematuria (CEH).
No full textThe FHIT (fragile histidine triad) gene is a tumor suppressor gene known to be inactivated in many tumors including bladder tumors and is spanning FRA3B, a very active common fragile site in the human genome. We have recently isolated the bovine gene, and the aim of this study was to test whether FHIT presents altered expression patterns in vesical tumors of cattle with CEH (chronic enzootic hematuria). CEH is a common syndrome affecting Mediterranean cattle: clastogenic, mutagenic and cancerogenic substances released by the bracken fern (Pteridium spp) grazed by animals induce the formation of neoplastic lesions, among which bladder tumors have a high incidence. We analysed FHIT in 23 bladder tumors of CEH cattle looking at: 1) the methylation status of the CpG island comprising the promoter and part of exon 1; 2) the presence of altered FHIT transcripts; 3) the mRNA expression levels measured with a quantitative real time PCR (QRT-PCR) approach. Our results suggest that unlike in human tumors, FHIT in vesical tumors of CEH cattle is largely unmethylated. Furthermore, the same mRNA isoforms of FHIT were detected in tumors and in healthy tissues, including a novel isoform that was found in this study. Finally, QRT-PCR data did not reveal significantly altered expression profiles of FHIT transcripts. Further studies and larger sets of cases will be useful to confirm this finding, but the data seem to suggest that epigenetic modifications of FHIT and altered expression profiles are not a hallmark of bovine vesical tumors like they are in human tumors
Long range restriction analysis of the bovine casein genes
Full text linkPulsed field gel electrophoresis (PFGE) was used to
analyse the organization of the bovine as1, as2, a and
x casein genes. High molecular weight DNA was
prepared from fibroblasts and lymphocytes embedded
in agarose and was digested with the restriction
endonucleases Clal, Sall, Smal, Xhol. The digestion
products were separated by PFGE, transfered to
nitrocellulose filters and hybridized to probes
corresponding to the cDNAs of the four bovine casein
genes. The casein genes were demonstrated to be
physically linked within a region of 300 kb, represented
by two adjacent Xhol fragments in fibroblasts and by
a single fragment in lymphocytes. A restriction map of
the casein locus was derived and the order of the genes
was shown to be x, as2, ,B, as1
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