CEPH, una piattaforma di archiviazione distribuita per applicazioni containerizzate

In questa tesi vogliamo analizzare il funzionamento della piattaforma di archiviazione distribuita chiamata Ceph. Faremo una breve introduzione in cui parleremo del sempre più crescente utilizzo dei micro-servizi, soprattutto in ambito cloud, e dell’ormai consolidata tecnologia dei container. Mostreremo le loro funzionalità concentrandoci su Docker, uno dei principali container engine, e di Docker Swarm, orchestrator di applicazioni containerizzate in ambienti Linux, cercando anche di portare alla luce le loro problematiche e necessità. Spiegheremo cosa si intende per Software Defined Storage, un’architettura moderna in cui lo spazio di storage viene astratto e definito via software tralasciando all’utente finale tutta la complessità dei dispostivi hardware sottostanti. Passeremo infine a parlare di Ceph, uno dei principali Software Defined Storage che promette diversi tipi di interfacce di utilizzo, per ogni tipo di applicazione e delle sue esigenze. Guarderemo in dettaglio la struttura del cluster e i vari servizi che lo compongono: Manager, OSD, MDS e MON, analizzando i principali algoritmi che sono alla base del suo funzionamento come Paxos e CRUSH. Il primo viene utilizzato in ambienti distribuiti per mantenere la consistenza dei dati tramite un sistema di accettazione tra i nodi del cluster; il secondo, invece, è un algoritmo pseudo-casuale che si occupa di dividere i dati tra i vari nodi del cluster e della loro ridondanza. Parleremo in dettaglio dei tre tipi di interfacce che Ceph mette a disposizione dei propri utilizzatori: ad oggetti, a blocchi ed a file, cercando di mostrare le loro caratteristiche e le loro differenze. Creeremo una piccola implementazione di Ceph, molto basilare, su cui monteremo dei dischi per creare uno spazio di storage ed un file system CephFS da utilizzare su una macchina client. Infine, verrà fatto un piccolo confronto con altri software SDS sul mercato per mostrare pregi e difetti di Ceph rispetto ai suoi concorrenti

Low-temperature stability and sensing performance of mid-infrared bloch surface waves on a one-dimensional photonic crystal

The growing need for new and reliable surface sensing methods is arousing interest in the electromagnetic excitations of ultrathin films, i.e., to generate electromagnetic field distributions that resonantly interact with the most significant quasi-particles of condensed matter. In such a context, Bloch surface waves turned out to be a valid alternative to surface plasmon polaritons to implement high-sensitivity sensors in the visible spectral range. Only in the last few years, however, has their use been extended to infrared wavelengths, which represent a powerful tool for detecting and recognizing molecular species and crystalline structures. In this work, we demonstrate, by means of high-resolution reflectivity measurements, that a one-dimensional photonic crystal can sustain Bloch surface waves in the infrared spectral range from room temperature down to 10 K. To the best of our knowledge, this is the first demonstration of infrared Bloch surface waves at cryogenic temperatures. Furthermore, by exploiting the enhancement of the surface state and the high brilliance of infrared synchrotron radiation, we demonstrate that the proposed BSW-based sensor has a sensitivity on the order of 2.9 cm–1 for each nanometer-thick ice layer grown on its surface below 150 K. In conclusion, we believe that Bloch surface wave-based sensors are a valid new class of surface mode-based sensors for applications in materials science

Alcohol Activates the Hedgehog Pathway and Induces Related Procarcinogenic Processes in the Alcohol-Preferring Rat Model of Hepatocarcinogenesis

Alcohol consumption promotes hepatocellular carcinoma (HCC). The responsible mechanisms are not well understood. Hepatocarcinogenesis increases with age and is enhanced by factors that impose a demand for liver regeneration. Because alcohol is hepatotoxic, habitual alcohol ingestion evokes a recurrent demand for hepatic regeneration. The alcohol-preferring (P) rat model mimics the level of alcohol consumption by humans who habitually abuse alcohol. Previously, we showed that habitual heavy alcohol ingestion amplified age-related hepatocarcinogenesis in P-rats, with over 80% of alcohol-consuming P rats developing HCCs after 18 months of alcohol exposure, compared to only 5% of water-drinking controls

Physical Mapping of Bread Wheat Chromosome 5A: An Integrated Approach

The huge size, redundancy, and highly repetitive nature of the bread wheat [Triticum aestivum (L.)] genome, makes it among the most difficult species to be sequenced. To overcome these limitations, a strategy based on the separation of individual chromosomes or chromosome arms and the subsequent production of physical maps was established within the frame of the International Wheat Genome Sequence Consortium (IWGSC). A total of 95,812 bacterial artificial chromosome (BAC) clones of short-arm chromosome 5A (5AS) and long-arm chromosome 5A (5AL) arm-specific BAC libraries were fingerprinted and assembled into contigs by complementary analytical approaches based on the FingerPrinted Contig (FPC) and Linear Topological Contig (LTC) tools. Combined anchoring approaches based on polymerase chain reaction (PCR) marker screening, microarray, and sequence homology searches applied to several genomic tools (i. e., genetic maps, deletion bin map, neighbor maps, BAC end sequences (BESs), genome zipper, and chromosome survey sequences) allowed the development of a high-quality physical map with an anchored physical coverage of 75% for 5AS and 53% for 5AL with high portions (64 and 48%, respectively) of contigs ordered along the chromosome. In the genome of grasses, Brachypodium [Brachypodium distachyon (L.) Beauv.], rice (Oryza sativa L.), and sorghum [Sorghum bicolor (L.) Moench] homologs of genes on wheat chromosome 5A were separated into syntenic blocks on different chromosomes as a result of translocations and inversions during evolution. The physical map presented represents an essential resource for fine genetic mapping and map-based cloning of agronomically relevant traits and a reference for the 5A sequencing projects

<title>Corona-poled azo-dye-doped silica films obtained by sol-gel processing</title>

SiO2 films doped with the organic dye DO3, exhibiting high electron delocalization have been prepared by the sol- gel method and deposited on soda-lime glass substrates. On these films an electric field of 5-7 kV/cm has been successively applied in order to induce orientation of the DO3 molecules and freeze them in the condition by heating and reticulation of the inorganic matrix. The thermal stability of the films and the variation of the molecules' orientation as a function of time have been studied. The films have been characterized by means of differential thermal analysis, thermogravimetry, mass spectrometry, ellipsometry and atomic force microscopy

Spectral Characterization of Mid-Infrared Bloch Surface Waves Excited on a Truncated 1D Photonic Crystal

The many fundamental roto-vibrational resonances of chemical compounds result in strong absorption lines in the mid-infrared region (λ ∼ 2–20 μm). For this reason, mid-infrared spectroscopy plays a key role in label-free sensing, in particular, for chemical recognition, but often lacks the required sensitivity to probe small numbers of molecules. In this work, we propose a vibrational sensing scheme based on Bloch surface waves (BSWs) on 1D photonic crystals to increase the sensitivity of mid-infrared sensors. We report on the design and deposition of CaF2/ZnS 1D photonic crystals. Moreover, we theoretically and experimentally demonstrate the possibility to sustain narrow σ-polarized BSW modes together with broader π-polarized modes in the range of 3–8 μm by means of a customized Fourier transform infrared spectroscopy setup. The multilayer stacks are deposited directly on CaF2 prisms, reducing the number of unnecessary interfaces when exciting in the Kretschmann–Raether configuration. Finally, we compare the performance of mid-IR sensors based on surface plasmon polaritons with the BSW-based sensor. The figures of merit found for BSWs in terms of confinement of the electromagnetic field and propagation length puts them as forefrontrunners for label-free and polarization-dependent sensing devices