Sviluppo di un array di idrofoni in fibra ottica basati sulla tecnologia DBR-FL

In questo elaborato mi propongo di discutere lo sviluppo di un idrofono in fibra ottica che possa sostituire i più comuni sensori piezoelettrici commerciali. L'interesse per un tale progetto è dovuto alle molteplici applicazioni possibili, dallo studio dei cetacei alla sicurezza, come la sorveglianza dei porti o aree sensibili marine, fino ad un possibile utilizzo come rivelatori di particelle, in particolare neutrini UHE. Il sensore analizzato si basa su un laser di tipo Fabry-Perot in cui la cavità è realizzata fotoincidendo reticoli di Bragg direttamente nel core della fibra drogata all'Erbio, formando così un DBR-FL. Quando una perturbazione incide sul laser lo sottopone a stress meccanico che ne varia la lunghezza d'onda di emissione, rendendo possibile la rivelazione della perturbazione stessa. Per aumentare ulteriormente la sensibilità dell'idrofono si utilizza una rivelazione interferometrica, grazie alla quale, si dimostra che il minimo segnale rivelabile è inversamente proporzionale allo sbilanciamento tra i bracci dell'interferometro. Grazie all'accurata progettazione della rivelazione interferometrica la minima perturbazione rivelabile diventa virtualmente, dell'ordine del DSS0, ovvero il rumore di fondo dell'oceano. Per migliorare ulteriormente le prestazioni dell'idrofono, e in particolare l'omogeneità della risposta su tutto il range di frequenze di interesse, il laser è ricoperto da un cilindro di materiale scelto accuratamente, la cui risposta in frequenza è stata studiata attraverso l'analisi dei modelli matematici di interazione acustica-strutturale. Le equazioni sono state risolte grazie all'utilizzo di un programma di simulazioni ad elementi finiti, il COMSOL Multiphysics, che ha permesso di calcolare teoricamente la deformazione dei materiali utilizzati come coating per il nostro idrofono. Infine, grazie alla possibilità offerta dal wavelenght-multiplexing, è stato sviluppato e testato in mare, quindi in ambiente non controllato, un array formato da 2 idrofoni, costruiti sulla medesima fibra ottica, e monitorati da remoto. Attualmente questa è la prima calibrazione in ambiente “reale” presente in letteratura di un array di idrofoni in fibra ottica

Advances in HCV Therapy

Hepatitis C is a devastating illness which has the potential in the majority of cases to lead to significant morbidity and mortality. Worldwide, the number living with chronic hepatitis C approaches 185 million. Up until recently, the regimen of peg-IFN and ribavirin stood as the standard of care and is still commonly used as first line therapy. This is rapidly changing. Direct acting antivirals have altered the landscape drastically. By understanding the genome of the hepatitis C virus, scientists and researchers have been able to exploit its mechanism of transmission by creating inhibitors against several of the nonstructural proteins that are integral to HCV replication and function [NS3/4 protease, NS5A polymerase, and NS5B polymerases (nucleoside and non-nucleoside)]. The previously reported 50%-70% SVR rates achieved with peg-IFN and RBV are no longer the standard of care. Thanks to direct acting antivirals, IFN free as well as “all oral” regimens are being used to treat HCV. In addition to this, ribavirin-free regimens are also available. These highly effective therapies also provide far less side effects and accomplish better results in less time, thus shortening treatment duration significantly. Additionally, even in the notoriously difficult -to-treat populations, results have been promising

Cambios en la gestión de la comunicación en una institución pública latinoamericana : 14 años del Centro de Fotografía de Montevideo

págs. 192-213.Capítulo incluido en el libro: Escenarios y desafíos de la comunicación y la cultura en el espacio audiovisual iberoamericano. Alexandro Escudero Nahón, Diana Elisa González Calderón (editores). Sevilla, Universidad Internacional de Andalucía, 2017. Págs.: 192-213. Enlace: http://hdl.handle.net/10334/383

Baseline MRI Predictors of Conversion from MCI to Probable AD in the ADNI Cohort

The Alzheimer’s Disease Neuroimaging Initiative (ADNI) is a multi-center study assessing neuroimaging in diagnosis and longitudinal monitoring. Amnestic Mild Cognitive Impairment (MCI) often represents a prodromal form of dementia, conferring a 10-15% annual risk of converting to probable AD. We analyzed baseline 1.5T MRI scans in 693 participants from the ADNI cohort divided into four groups by baseline diagnosis and one year MCI to probable AD conversion status to identify neuroimaging phenotypes associated with MCI and AD and potential predictive markers of imminent conversion. MP-RAGE scans were analyzed using publicly available voxel-based morphometry (VBM) and automated parcellation methods. Measures included global and hippocampal grey matter (GM) density, hippocampal and amygdalar volumes, and cortical thickness values from entorhinal cortex and other temporal and parietal lobe regions. The overall pattern of structural MRI changes in MCI (n=339) and AD (n=148) compared to healthy controls (HC, n=206) was similar to prior findings in smaller samples. MCI-Converters (n=62) demonstrated a very similar pattern of atrophic changes to the AD group up to a year before meeting clinical criteria for AD. Finally, a comparison of effect sizes for contrasts between the MCI-Converters and MCI-Stable (n=277) groups on MRI metrics indicated that degree of neurodegeneration of medial temporal structures was the best antecedent MRI marker of imminent conversion, with decreased hippocampal volume (left > right) being the most robust. Validation of imaging biomarkers is important as they can help enrich clinical trials of disease modifying agents by identifying individuals at highest risk for progression to AD

Efficacy and safety of simeprevir and sofosbuvir with and without ribavirin in subjects with recurrent genotype 1 hepatitis C postorthotopic liver transplant: the randomized GALAXY study

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136282/1/tri12896.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136282/2/tri12896_am.pd

Enhancers in embryonic stem cells are enriched for transposable elements and genetic variations associated with cancers

Using an enhancer-associated epigenetic signature, we made genome-wide predictions of transcriptional enhancers in human B and T lymphocytes and embryonic stem cells (ES cells). We validated and characterized the predicted enhancers using four types of information, including overlap with other genomic marks for enhancers; association with cell-type-specific genes; enrichment of cell-type-specific transcription factor binding sites; and genetic polymorphisms in predicted enhancers. We find that enhancers from ES cells, but not B or T cells, are significantly enriched for DNA sequences derived from transposable elements. This may be due to the generally relaxed repressive epigenetic state and increased activity of transposable elements in ES cells. We demonstrate that the wealth of new enhancer sequences discerned here provides an invaluable resource for the functional annotation of gene-distal single nucleotide polymorphisms identified through expression quantitative trait loci and genome-wide association studies analyses. Notably, we find GWAS SNPs associated with various cancers are enriched in ES cell enhancers. In comparison, GWAS SNPs associated with diseases due to immune dysregulation are enriched in B and T cell enhancers

Genome-wide enhancer prediction from epigenetic signatures using genetic algorithm-optimized support vector machines

The chemical modification of histones at specific DNA regulatory elements is linked to the activation, inactivation and poising of genes. A number of tools exist to predict enhancers from chromatin modification maps, but their practical application is limited because they either (i) consider a smaller number of marks than those necessary to define the various enhancer classes or (ii) work with an excessive number of marks, which is experimentally unviable. We have developed a method for chromatin state detection using support vector machines in combination with genetic algorithm optimization, called ChromaGenSVM. ChromaGenSVM selects optimum combinations of specific histone epigenetic marks to predict enhancers. In an independent test, ChromaGenSVM recovered 88% of the experimentally supported enhancers in the pilot ENCODE region of interferon gamma-treated HeLa cells. Furthermore, ChromaGenSVM successfully combined the profiles of only five distinct methylation and acetylation marks from ChIP-seq libraries done in human CD4+ T cells to predict ∼21 000 experimentally supported enhancers within 1.0 kb regions and with a precision of ∼90%, thereby improving previous predictions on the same dataset by 21%. The combined results indicate that ChromaGenSVM comfortably outperforms previously published methods and that enhancers are best predicted by specific combinations of histone methylation and acetylation marks