Mott transition in bosonic systems: Insights from the variational approach

We study the Mott transition occurring for bosonic Hubbard models in one, two, and three spatial dimensions, by means of a variational wave function benchmarked by Green's function Monte Carlo calculations. We show that a very accurate variational wave function, constructed by applying a long-range Jastrow factor to the non-interacting boson ground state, can describe the superfluid-insulator transition in any dimensionality. Moreover, by mapping the quantum averages over such a wave function into the the partition function of a classical model, important insights into the insulating phase are uncovered. Finally, the evidence in favor of anomalous scenarios for the Mott transition in two dimensions are reported whenever additional long-range repulsive interactions are added to the Hamiltonian.Comment: 12 pages and 19 figures. Related to arXiv:0705.268

Nanoparticle-based techniques for bladder cancer imaging: a review

Bladder cancer is very common in humans and is often characterized by recurrences, compromising the patient's quality of life with a substantial social and economic impact. Both the diagnosis and treatment of bladder cancer are problematic due to the exceptionally impermeable barrier formed by the urothelium lining the bladder; this hinders the penetration of molecules via intravesical instillation while making it difficult to precisely label the tumor tissue for surgical resection or pharmacologic treatment. Nanotechnology has been envisaged as an opportunity to improve both the diagnostic and therapeutic approaches for bladder cancer since the nanoconstructs can cross the urothelial barrier and may be functionalized for active targeting, loaded with therapeutic agents, and visualized by different imaging techniques. In this article, we offer a selection of recent experimental applications of nanoparticle-based imaging techniques, with the aim of providing an easy and rapid technical guide for the development of nanoconstructs to specifically detect bladder cancer cells. Most of these applications are based on the well-established fluorescence imaging and magnetic resonance imaging currently used in the medical field and gave positive results on bladder cancer models in vivo, thus opening promising perspectives for the translation of preclinical results to the clinical practice

Are Italy's public finances sustainable? The role of demographics, productivity, and labour markets.

In light of the uncertainty of the effects of population ageing on growth and fiscal variables, it is sensible to ask whether Italy's public finances can achieve sustainability under the spending pressure exerted by future demographic and macroeconomic developments. The paper addresses this question by assessing long-term fiscal sustainability, following the commonlyagreed European methodology, under alternative scenarios considering a variety of issues that may have a bearing on Italy's public finance conditions, namely, immigration, life expectancy, female labour participation, and productivity growth. Despite the different hypotheses captured by the alternative scenarios, the paper finds that projected debt-to-GDP ratios decrease over time, as long as fiscal consolidation is achieved in the near future. It also shows a one-shot debt-reduction strategy is not a credible substitute for a budgetary-adjustment strategy. The paper concludes Italy's public finances are sustainable and can deal with future spending pressures resulting from the ageing population.Fiscal Sustainability, Fiscal Policy

Superfluid to Mott-insulator transition in Bose-Hubbard models

We study the superfluid-insulator transition in Bose-Hubbard models in one-, two-, and three-dimensional cubic lattices by means of a recently proposed variational wave function. In one dimension, the variational results agree with the expected Berezinskii-Kosterlitz-Thouless scenario of the interaction-driven Mott transition. In two and three dimensions, we find evidences that, across the transition,most of the spectral weight is concentrated at high energies, suggestive of pre-formed Mott-Hubbard side-bands. This result is compatible with the experimental data by Stoferle et al. [Phys. Rev. Lett. 92, 130403 (2004)].Comment: 4 pages, 4 figures, based on cond-mat/061130

Good, Green, Safe, Affordable Housing

In May 2007, the Council of European Ministers for Urban development set out the Leipzig Charter: an ambitious document for the future of our cities, advocating a new way of working on our environment. One year later, European cities face the task of bringing those propositions to life, providing higher-quality housing for more and more citizens, making access to affordable housing as simple as possible. In times of economic drought this might not prove easy: yet the real challenge consists in governing the economic forces which shape our cities, organising them through processes involving both public authorities and private stakeholders from the outset, reducing conflicts along the way. Good housing is what shapes our cities, creating space and the quality to make them attractive places to live and work in. Green housing is needed to mitigate environmental impact, reduce energy consumption, create buildings which interact more efficiently with the environment, and produce less pollution. Safe housing is important to protect the wellbeing – both physiological and psychological – of its inhabitants, helping cities acquire that quality of life which makes them attractive places to live and work in. Affordable housing is fundamental to guarantee the widest access to high-quality living to citizens of all income, by controlling the housing market, building costs and energy costs. The aim of the Urbact II Working Group Hopus – Housing Praxis for Urban Sustainability – is exactly this: to study, disseminate and implement the ways through which new housing in Europe can be efficiently oriented, using modern governance tools such as design codes or other forms of “smart” project guidance. Hopus brings together five universities and two city administrations, each working on different aspects of housing. From the urban to the building approach, from building regulations to construction technology, from environmental quality to energy certification: a multi-faceted and interdisciplinary approach, trying to cover a wide range of different problems, joining theory and practice. The challenge set out by the Leipzig Charter may seem vast; nevertheless, it is only through joint efforts that we can truly aspire to better new housing developments – good, green, safe, and affordable – which will eventually give birth to the cities we want for the future of our continent

Direct vs 2-stage approaches to structured motif finding

BACKGROUND: The notion of DNA motif is a mathematical abstraction used to model regions of the DNA (known as Transcription Factor Binding Sites, or TFBSs) that are bound by a given Transcription Factor to regulate gene expression or repression. In turn, DNA structured motifs are a mathematical counterpart that models sets of TFBSs that work in concert in the gene regulations processes of higher eukaryotic organisms. Typically, a structured motif is composed of an ordered set of isolated (or simple) motifs, separated by a variable, but somewhat constrained number of “irrelevant” base-pairs. Discovering structured motifs in a set of DNA sequences is a computationally hard problem that has been addressed by a number of authors using either a direct approach, or via the preliminary identification and successive combination of simple motifs. RESULTS: We describe a computational tool, named SISMA, for the de-novo discovery of structured motifs in a set of DNA sequences. SISMA is an exact, enumerative algorithm, meaning that it finds all the motifs conforming to the specifications. It does so in two stages: first it discovers all the possible component simple motifs, then combines them in a way that respects the given constraints. We developed SISMA mainly with the aim of understanding the potential benefits of such a 2-stage approach w.r.t. direct methods. In fact, no 2-stage software was available for the general problem of structured motif discovery, but only a few tools that solved restricted versions of the problem. We evaluated SISMA against other published tools on a comprehensive benchmark made of both synthetic and real biological datasets. In a significant number of cases, SISMA outperformed the competitors, exhibiting a good performance also in most of the cases in which it was inferior. CONCLUSIONS: A reflection on the results obtained lead us to conclude that a 2-stage approach can be implemented with many advantages over direct approaches. Some of these have to do with greater modularity, ease of parallelization, and the possibility to perform adaptive searches of structured motifs. As another consideration, we noted that most hard instances for SISMA were easy to detect in advance. In these cases one may initially opt for a direct method; or, as a viable alternative in most laboratories, one could run both direct and 2-stage tools in parallel, halting the computations when the first halts

Alzheimer's disease gene signature says: beware of brain viral infections

<p>Abstract</p> <p>Background</p> <p>Recent findings from a genome wide association investigation in a large cohort of patients with Alzheimer's disease (AD) and non demented controls (CTR) showed that a limited set of genes was in a strong association (p > l0^-5) with the disease.</p> <p>Presentation of the hypothesis</p> <p>In this report we suggest that the polymorphism association in 8 of these genes is consistent with a non conventional interpretation of AD etiology.</p> <p>Nectin-2 (NC-2), apolipoprotein E (APOE), glycoprotein carcinoembryonic antigen related cell adhesion molecule- 16 (CEACAM-16), B-cell lymphoma-3 (Bcl-3), translocase of outer mitochondrial membrane 40 homolog (T0MM-40), complement receptor-1 (CR-l), APOJ or clusterin and C-type lectin domain A family-16 member (CLEC-16A) result in a genetic signature that might affect individual brain susceptibility to infection by herpes virus family during aging, leading to neuronal loss, inflammation and amyloid deposition.</p> <p>Implications of the hypothesis</p> <p>We hypothesized that such genetic trait may predispose to AD via complex and diverse mechanisms each contributing to an increase of individual susceptibility to brain viral infections</p

Antimicrobial and antibiofilm activity and machine learning classification analysis of essential oils from different mediterranean plants against pseudomonas aeruginosa

Pseudomonas aeruginosa is a ubiquitous organism and opportunistic pathogen that can cause persistent infections due to its peculiar antibiotic resistance mechanisms and to its ability to adhere and form biofilm. The interest in the development of new approaches for the prevention and treatment of biofilm formation has recently increased. The aim of this study was to seek new non-biocidal agents able to inhibit biofilm formation, in order to counteract virulence rather than bacterial growth and avoid the selection of escape mutants. Herein, different essential oils extracted from Mediterranean plants were analyzed for their activity againstP. aeruginosa. Results show that they were able to destabilize biofilm at very low concentration without impairing bacterial viability. Since the action is not related to a bacteriostatic/bactericidal activity onP. aeruginosa, the biofilm change of growth in presence of the essential oils was possibly due to a modulation of the phenotype. To this aim, application of machine learning algorithms led to the development of quantitative activity-composition relationships classification models that allowed to direct point out those essential oil chemical components more involved in the inhibition of biofilm production. The action of selected essential oils on sessile phenotype make them particularly interesting for possible applications such as prevention of bacterial contamination in the community and in healthcare environments in order to prevent human infections. We assayed 89 samples of different essential oils asP. aeruginosaanti-biofilm. Many samples inhibitedP. aeruginosabiofilm at concentrations as low as 48.8 µg/mL. Classification of the models was developed through machine learning algorithms