Janus II: a new generation application-driven computer for spin-system simulations

This paper describes the architecture, the development and the implementation of Janus II, a new generation application-driven number cruncher optimized for Monte Carlo simulations of spin systems (mainly spin glasses). This domain of computational physics is a recognized grand challenge of high-performance computing: the resources necessary to study in detail theoretical models that can make contact with experimental data are by far beyond those available using commodity computer systems. On the other hand, several specific features of the associated algorithms suggest that unconventional computer architectures, which can be implemented with available electronics technologies, may lead to order of magnitude increases in performance, reducing to acceptable values on human scales the time needed to carry out simulation campaigns that would take centuries on commercially available machines. Janus II is one such machine, recently developed and commissioned, that builds upon and improves on the successful JANUS machine, which has been used for physics since 2008 and is still in operation today. This paper describes in detail the motivations behind the project, the computational requirements, the architecture and the implementation of this new machine and compares its expected performances with those of currently available commercial systems.Comment: 28 pages, 6 figure

Validation of Observed Bedload Transport Pathways Using Morphodynamic Modeling

Phenomena related to braiding, including local scour and fill, channel bar development, migration and avulsion, make numerical morphodynamic modeling of braided rivers challenging. This paper investigates the performance of a Delft3D model, in a 2D depth-averaged formulation, to simulate the morphodynamics of an anabranch of the Rees River (New Zealand). Model performance is evaluated using data from field surveys collected on the falling limb of a major high flow, and using several sediment transport formulas. Initial model results suggest that there is generally good agreement between observed and modeled bed levels. However, some discrepancies in the bed level estimations were noticed, leading to bed level, water depth and water velocity estimation errors

Valutazione delle caratteristiche fisiche e strutturali di un prodotto da forno durante la conservazione (Spianata di Ozieri)

The aim of this research was the characterization by physical and structural properties, a typical bakery product (Spianata di Ozieri). The samples of two differents kind of spianata were submitted to dynamometric analysis (texture profile analysis - TPA, cut and tension test), color measurement and microbiological tests over 14 days of storage time at 22°C. Three samplings were conducted in different periods of the year to test the seasonality of the production. A collaborative test was carried out at the DISAABA (Sassari University) and in the laboratories of Food Science & Technology (Bologna University). The most important results obtained in this research confirm effectivement that this kind of product is really typical and so the data variability obtained is quite normal. The microciological tests showed a good quality of the product during the normal storage time. Lo scopo di questa ricerca è stato quello di effettuare una prima caratterizzazione fisica e strutturale di un prodotto da forno tipico sardo, la spianata di Ozieri. In particolare, sono state studiate le variazioni di alcune caratteristiche strutturali dinamometriche, fisiche e chimico-fisiche e l'evoluzione della carica microbica durante la conservazione, a temperatura controllata di 22°C circa, di due diversi campioni commerciali di spianata sarda, realizzati artigianalmente e confezionati con metodologie diverse: uno in atmosfera ordinaria e destinato al mercato locale e l'altro confezionato in atmosfera protettiva (40% anidride carbonica, 60% azoto) e destinato alla grande distribuziooe. Sono stati effettuati tre campionamenti nei mesi di luglio, novembre e gennaio, per valutare eventuali differenze dovute alia stagionalità di produzione. Le prove sono state condotte in collaborazione tra i laboratori del Disaaba dell'Università di Sassari e del Corso di Laurea in Scienze e Tecnologie Alimentari di Cesena, Università di Bologna. Sono stati analizzati i campioni delle due differenti produzioni e dei tre diversi campionamenti stagionali, valutando le modificazioni delle caratteristiche fisiche in conservazione, mentre l'evoluzione della carica microbica è stata valutata sulla campionatura di gennaio. Si riporteranno di seguito, i risultati ottenuti durante il periodo di osservazione, della durata di 14 giorni per campioni confezionati in atmosfera ordinaria e di 27 giomi per quelli condizionati in atmosfera protettiva

Simulating spin systems on IANUS, an FPGA-based computer

We describe the hardwired implementation of algorithms for Monte Carlo simulations of a large class of spin models. We have implemented these algorithms as VHDL codes and we have mapped them onto a dedicated processor based on a large FPGA device. The measured performance on one such processor is comparable to O(100) carefully programmed high-end PCs: it turns out to be even better for some selected spin models. We describe here codes that we are currently executing on the IANUS massively parallel FPGA-based system.Comment: 19 pages, 8 figures; submitted to Computer Physics Communication

Nanoparticle transport across the blood brain barrier

ABSTRACT: While the role of the blood-brain barrier (BBB) is increasingly recognized in the (development of treatments targeting neurodegenerative disorders, to date, few strategies exist that enable drug delivery of non-BBB crossing molecules directly to their site of action, the brain. However, the recent advent of Nanomedicines may provide a potent tool to implement CNS targeted delivery of active compounds. Approaches for BBB crossing are deeply investigated in relation to the pathology: among the main important diseases of the CNS, this review focuses on the application of nanomedicines to neurodegenerative disorders (Alzheimer, Parkinson and Huntington's Disease) and to other brain pathologies as epilepsy, infectious diseases, multiple sclerosis, lysosomal storage disorders, strokes

Host-cell dependent role of phosphorylated keratin 8 during influenza A/NWS/33 virus (H1N1) infection in mammalian cells

In this study, we investigated the involvement of keratin 8 during human influenza A/NWS/33 virus (H1N1) infection in semi-permissive rhesus monkey-kidney (LLC-MK2) and permissive human type II alveolar epithelial (A549) cells. In A549 cells, keratin 8 showed major expression and phosphorylation levels. Influenza A/NWS/33 virus was able to subvert keratin 8 structural organization at late stages of infection in both cell models, promoting keratin 8 phosphorylation in A549 cells at early phases of infection. Accordingly, partial colocalizations of the viral nucleoprotein with keratin 8 and its phosphorylated form were assessed by confocal microscopy at early stages of infection in A549 cells. The employment of chemical activators of phosphorylation resulted in structural changes as well as increased phosphorylation of keratin 8 in both cell models, favoring the influenza A/NWS/33 virus's replicative efficiency in A549 but not in LLC-MK2 cells. In A549 and human larynx epidermoid carcinoma (HEp-2) cells inoculated with respiratory secretions from pediatric patients positive for, respectively, influenza A virus or respiratory syncytial virus, the keratin 8 phosphorylation level had increased only in the case of influenza A virus infection. The results obtained suggest that in A549 cells the influenza virus is able to induce keratin 8 phosphorylation thereby enhancing its replicative efficiency