Breakdown of the Onsager principle as a sign of aging

We discuss the problem of the equivalence between Continuous Time Random Walk (CTRW) and Generalized Master Equation (GME). The walker, making instantaneous jumps from one site of the lattice to another, resides in each site for extended times. The sojourn times have a distribution psi(t) that is assumed to be an inverse power law. We assume that the Onsager principle is fulfilled, and we use this assumption to establish a complete equivalence between GME and the Montroll-Weiss CTRW. We prove that this equivalence is confined to the case when psi(t) is an exponential. We argue that is so because the Montroll-Weiss CTRW, as recently proved by Barkai [E. Barkai, Phys. Rev. Lett. 90, 104101 (2003)], is non-stationary, thereby implying aging, while the Onsager principle, is valid only in the case of fully aged systems. We consider the case of a dichotomous fluctuation, and we prove that the Onsager principle is fulfilled for any form of regression to equilibrium provided that the stationary condition holds true. We set the stationary condition on both the CTRW and the GME, thereby creating a condition of total equivalence, regardless the nature of the waiting time distribution. As a consequence of this procedure we create a GME that it is a "bona fide" master equation, in spite of being non-Markovian. We note that the memory kernel of the GME affords information on the interaction between system of interest and its bath. The Poisson case yields a bath with infinitely fast fluctuations. We argue that departing from the Poisson form has the effect of creating a condition of infinite memory and that these results might be useful to shed light into the problem of how to unravel non-Markovian master equations.Comment: one file .tex, revtex4 style, 11 page

Efficacy of acoustic waves in preventing Streptococcus mutans adhesion on dental unit water line

Background: nei riuniti odontoiatrici, la qualità dell'acqua utilizzata per la refrigerazione e il risciacquo di manipoli, siringhe e altri componenti è un aspetto di notevole importanza sanitaria. L'acqua attraversa questi dispositivi mediante un circuito interconnesso di tubi di piccole dimensioni (circa 2 mm di diametro), denominato “dental unit water line” (DUWL). I DUWL possono essere fortemente colonizzati da varie specie batteriche sia in fase planctonica, che adesi o organizzati in biofilm, rappresentando una potenziale causa di infezione, non solo per i professionisti che usano abitualmente questi dispositivi, ma anche per pazienti occasionali, in particolare per i pazienti immunocompromessi. La contaminazione dei DUWL può essere prevenuta o ridotta con l'uso dei disinfettanti, ma l'eradicazione dei microrganismi adesi alle superfici interne dei DUWL o organizzati in forma di biofilm, è una sfida assai più complessa e spesso i normali metodi di disinfezione non sono pienamente efficaci. Inoltre, in ambito odontoiatrico, i disinfettanti utilizzati abitualmente per disinfettare i DUWL possono alterare la capacità adesiva del materiale utilizzato nella pratica restaurativa. Obiettivi: individuare una strategia innovativa, in grado di contrastare l'adesione batterica alle superfici dei DUWL mediante un approccio di tipo fisico, che sia più efficace nel superare il problema della contaminazione dei DUWL e ridurre il rischio di infezione rispetto ai normali metodi già in uso. A tal fine, fra le molte specie batteriche potenzialmente riscontrabili nei circuiti idrici odontoiatrici, si è deciso di avviare questo studio pilota utilizzando la specie batterica patogena S. mutans, per il suo indubbio interesse in ambito odontoiatrico e per la sua spiccata capacità di aderire e persistere su superfici inerti. Metodi: utilizzo di onde acustiche elastiche ad alta energia nel contrastare l'adesione di Streptococcus mutans alle pareti interne di un circuito idrico sperimentale riproducente un DUWL. Per evidenziare l’efficacia delle onde acustiche anche in condizioni estreme, è stata utilizzata un’elevata carica contaminante di S. mutans. Risultati: Si osserva una significativa riduzione dei batteri adesi soggetti a trattamento con onde acustiche rispetto al controllo (P = 0,003)

Conflict between trajectories and density description: the statistical source of disagreement

We study an idealized version of intermittent process leading the fluctuations of a stochastic dichotomous variable $\xi$. It consists of an overdamped and symmetric potential well with a cusp-like minimum. The right-hand and left-hand portions of the potential corresponds to $\xi = W$ and $\xi = -W$, respectively. When the particle reaches this minimum is injected back to a different and randomly chosen position, still within the potential well. We build up the corresponding Frobenius-Perron equation and we evaluate the correlation function of the stochastic variable $\xi$, called $\Phi_{\xi}(t)$. We assign to the potential well a form yielding $\Phi_{\xi}(t) = (T/(t + T))^{\beta}$, with $\beta > 0$. We limit ourselves to considering correlation functions with an even number of times, indicated for concision, by $$,$$ and, more, in general, by $$. The adoption of a treatment based on density yields $= ...$. We study the same dynamic problem using trajectories, and we establish that the resulting two-time correlation function coincides with that afforded by the density picture, as it should. We then study the four-times correlation function and we prove that in the non-Poisson case it departs from the density prescription, namely, from $=$. We conclude that this is the main reason why the two pictures yield two different diffusion processes, as noticed in an earlier work [M. Bologna, P. Grigolini, B.J. West, Chem. Phys. {\bf 284}, (1-2) 115-128 (2002)].Comment: 8 pages, no figure

Correlation function and generalized master equation of arbitrary age

We study a two-state statistical process with a non-Poisson distribution of sojourn times. In accordance with earlier work, we find that this process is characterized by aging and we study three different ways to define the correlation function of arbitrary age of the corresponding dichotomous fluctuation based respectively on the Generalized Master Equation formalism, on a Liouville-like approach and on a trajectory perspective.Comment: 11 pages, 1figur

Design of an Innovative Graphite Exchanger for Adsorption Heat Pumps and Chillers

Abstract In this work, an innovative adsorber for application in adsorption heat pumps and chillers is presented. The adsorber consists of several assembled graphite plates and the flow path of heat transfer fluid. Each plate consists of a process side (where zeolite is deposited onto) and a heat transfer fluid (HTF) side where liquid water flows. The resulting adsorbent heat exchanger is able to deliver about 0.5-1 kW cooling power and possesses attractive thermo physical properties, especially in term of low weight, volume and thermal capacity. Experimental testing of the full-scale adsorber by a testing station available at CNR ITAE is currently ongoing

Genotyping-by-sequencing of a melon (Cucumis melo L.) germplasm collection from a secondary center of diversity highlights patterns of genetic variation and genomic features of different gene pools

Background: Melon (Cucumis melo L.) is one of the most important horticultural species, which includes several taxonomic groups. With the advent of next-generation sequencing, single nucleotide polymorphism (SNP) markers are widely used in the study of genetic diversity and genomics. Results: We report the first successful application of genotyping-by-sequencing (GBS) technology in melon. We detected 25,422 SNPs by the analysis of 72 accessions collected in Apulia, a secondary centre of diversity in Southern Italy. Analyses of genetic structure, principal components, and hierarchical clustering support the identification of three distinct subpopulations. One of them includes accessions known with the folk name of 'carosello', referable to the chate taxonomic group. This is one of the oldest domesticated forms of C. melo, once widespread in Europe and now exposed to the risk of genetic erosion. The second subpopulation contains landraces of 'barattiere', a regional vegetable production that was never characterized at the DNA level and we show was erroneously considered another form of chate melon. The third subpopulation includes genotypes of winter melon (C. melo var. inodorus). Genetic analysis within each subpopulation revealed patterns of diversity associated with fruit phenotype and geographical origin. We used SNP data to describe, for each subpopulation, the average linkage disequilibrium (LD) decay, and to highlight genomic regions possibly resulting from directional selection and associated with phenotypic variation. Conclusions: We used GBS to characterize patterns of genetic diversity and genomic features within C. melo. We provide useful information to preserve endangered gene pools and to guide the use of germplasm in breeding. Finally, our findings lay a foundation for molecular breeding approaches and the identification of genes underlying phenotypic traits

Non-Poisson processes: regression to equilibrium versus equilibrium correlation functions

We study the response to perturbation of non-Poisson dichotomous fluctuations that generate super-diffusion. We adopt the Liouville perspective and with it a quantum-like approach based on splitting the density distribution into a symmetric and an anti-symmetric component. To accomodate the equilibrium condition behind the stationary correlation function, we study the time evolution of the anti-symmetric component, while keeping the symmetric component at equilibrium. For any realistic form of the perturbed distribution density we expect a breakdown of the Onsager principle, namely, of the property that the subsequent regression of the perturbation to equilibrium is identical to the corresponding equilibrium correlation function. We find the directions to follow for the calculation of higher-order correlation functions, an unsettled problem, which has been addressed in the past by means of approximations yielding quite different physical effects.Comment: 30 page

Shaping ability of Procodile and R6 Reziflow nickel-titanium reciprocating instruments in curved mesial root canals of mandibular molars: A MicroCT study

To compare the shaping ability of Procodileand R6 Reziflow instruments used in reciprocating motion in severely curved root canals, assessed with micro-computed tomography (mu CT). Fourteen extracted human mandibular first molars were randomly assigned to two instrumentation techniques (n = 14 mesial root canals): Procodile or R6 Reziflow. For both groups, root canals were prepared to the working length up to a size 25,.06 taper. Molars were virtually divided into apical, middle and coronal thirds and mu CT was used to scan all samples pre- and post-root canal. Canal transportation, centring ability, volume, surface area and unprepared area were evaluated. Geometrical parameter changes were compared with preoperative values (one-way analyses of variance and Tukey multiple comparison post-hoc test) between groups and Student t-test within groups (alpha = 0.05) Significantly less transportation was observed associated with the Procodile technique in the molar's coronal third compared to the R6 Reziflow technique (p <.05). No significant differences in root canal centring ability, volume, surface area and unprepared area were observed. Procodile showed a lower percentage increase of surface area compared to R6 Reziflow (p <.05). The Procodile and R6 Reziflow techniques applied to first molar root canal performed similarly except for the less transportation observed in the coronal third using Procodile.Research Highlights MicroCT analysis of canal geometry before and after instrumentation revealed that Procodile and R6 Reziflow showed a similar shaping ability to shape curved root canals without substantially modifications of the original tooth anatomy

A Distinct Genetic Cluster in Cultivated Chickpea as Revealed by Genome-wide Marker Discovery and Genotyping

The accurate description of plant biodiversity is of utmost importance to efficiently address efforts in conservation genetics and breeding. Herein, we report the successful application of a genotyping-by-sequencing (GBS) approach in chickpea ( L.), resulting in the characterization of a cultivated germplasm collection with 3187 high-quality single nucleotide polymorphism (SNP) markers. Genetic structure inference, principal component analysis, and hierarchical clustering all indicated the identification of a genetic cluster corresponding to black-seeded genotypes traditionally cultivated in Southern Italy. Remarkably, this cluster was clearly distinct at both genetic and phenotypic levels from germplasm groups reflecting commercial chickpea classification into and seed types. Fixation index estimates for individual polymorphisms pointed out loci and genomic regions that might be of significance for the diversification of agronomic and commercial traits. Overall, our findings provide information on genetic relationships within cultivated chickpea and highlight a gene pool of great interest for the scientific community and chickpea breeding, which is limited by the low genetic diversity available in the primary gene pool