The Fully Frustrated Hypercubic Model is Glassy and Aging at Large DD

We discuss the behavior of the fully frustrated hypercubic cell in the infinite dimensional mean-field limit. In the Ising case the system undergoes a glass transition, well described by the random orthogonal model. Under the glass temperature aging effects show clearly. In the $XY$ case there is no sign of a phase transition, and the system is always a paramagnet.Comment: Figures added in uufiles format, and epsf include

Spectroscopic survey of M--type asteroids

M-type asteroids, as defined in the Tholen taxonomy (Tholen, 1984), are medium albedo bodies supposed to have a metallic composition and to be the progenitors both of differentiated iron-nickel meteorites and enstatite chondrites. We carried out a spectroscopic survey in the visible and near infrared wavelength range (0.4-2.5 micron) of 30 asteroids chosen from the population of asteroids initially classified as Tholen M -types, aiming to investigate their surface composition. The data were obtained during several observing runs during the years 2004-2007 at the TNG, NTT, and IRTF telescopes. We computed the spectral slopes in several wavelength ranges for each observed asteroid, and we searched for diagnostic spectral features. We confirm a large variety of spectral behaviors for these objects as their spectra are extended into the near-infrared, including the identification of weak absorption bands, mainly of the 0.9 micron band tentatively attributed to orthopyroxene, and of the 0.43 micron band that may be associated to chlorites and Mg-rich serpentines or pyroxene minerals such us pigeonite or augite. A comparison with previously published data indicates that the surfaces of several asteroids belonging to the M-class may vary significantly. We attempt to constrain the asteroid surface compositions of our sample by looking for meteorite spectral analogues in the RELAB database and by modelling with geographical mixtures of selected meteorites/minerals. We confirm that iron meteorites, pallasites, and enstatite chondrites are the best matches to most objects in our sample, as suggested for M-type asteroids. The presence of subtle absorption features on several asteroids confirms that not all objects defined by the Tholen M-class have a pure metallic composition.Comment: 10 figures, 6 tables; Icarus, in pres

Replica Field Theory for Deterministic Models (II): A Non-Random Spin Glass with Glassy Behavior

We introduce and study a model which admits a complex landscape without containing quenched disorder. Continuing our previous investigation we introduce a disordered model which allows us to reconstruct all the main features of the original phase diagram, including a low $T$ spin glass phase and a complex dynamical behavior.Comment: 35 pages with uu figures, Roma 102

Promoting data provenance tracking in the archaeological interpretation process

n this paper we propose a model and a set of derivation rules for tracking data provenance during the archaeological interpretation process. The interpretation process is the main task performed by an archaeologist that, starting from ground data about evidences and findings, tries to derive knowledge about an ancient object or event. In particular, in this work we concentrate on the dating process used by archaeologists to assign one or more time intervals to a finding in order to define its lifespan on the temporal axis and we propose a framework to represent such information and infer new knowledge including provenance of data. Archaeological data, and in particular their temporal dimension, are typically vague, since many different interpretations can coexist, thus we will use Fuzzy Logic to assign a degree of confidence to values and Fuzzy Temporal Constraint Networks to model relationships between dating of different finding

A context-based approach for partitioning big data

In recent years, the amount of available data keeps growing at fast rate, and it is therefore crucial to be able to process them in an efficient way. The level of parallelism in tools such as Hadoop or Spark is determined, among other things, by the partitioning applied to the dataset. A common method is to split the data into chunks considering the number of bytes. While this approach may work well for text-based batch processing, there are a number of cases where the dataset contains structured information, such as the time or the spatial coordinates, and one may be interested in exploiting such a structure to improve the partitioning. This could have an impact on the processing time and increase the overall resource usage efficiency. This paper explores an approach based on the notion of context, such as temporal or spatial information, for partitioning the data. We design a context-based multi-dimensional partitioning technique that divides an n 12dimensional space into splits by considering the distribution of the each contextual dimension in the dataset. We tested our approach on a dataset from a touristic scenario, and our experiments show that we are able to improve the efficiency of the resource usage

What is the role of context in fair group recommendations?

We investigate the role played by the context, i.e. the situation the group is currently experiencing, in the design of a system that recommends sequences of activities as a multi-objective optimization problem, where the satisfaction of the group and the available time interval are two of the functions to be optimized. In particular, we highlight that the dynamic evolution of the group can be the key contextual feature that has to be considered to produce fair suggestions

Dynamical Behaviour of Low Autocorrelation Models

We have investigated the nature of the dynamical behaviour in low autocorrelation binary sequences. These models do have a glass transition $T_G$ of a purely dynamical nature. Above the glass transition the dynamics is not fully ergodic and relaxation times diverge like a power law $\tau\sim (T-T_G)^{-\gamma}$ with $\gamma$ close to $2$. Approaching the glass transition the relaxation slows down in agreement with the first order nature of the dynamical transition. Below the glass transition the system exhibits aging phenomena like in disordered spin glasses. We propose the aging phenomena as a precise method to determine the glass transition and its first order nature.Comment: 19 pages + 14 figures, LateX, figures uuencoded at the end of the fil

Single cell cloning and recombinant monoclonal antibodies generation from RA synovial B cells reveal frequent targeting of citrullinated histones of NETs

This work was funded by research grants from Arthritis Research UK (grant 20089 to MB; grant 20858 to ECo; Arthritis Research UK Experimental Arthritis Treatment Centre - grant 20022 to CP) and the William Harvey Research Foundation (WHRF grant 2011–2013 to MB); Elisa Corsiero was recipient of short-term travel fellowships from EMBO (ASTF 318-2010 and ASTF 102-2013

Differential structural remodelling of heparan sulfate by chemokines: the role of chemokine oligomerization

Chemokines control the migration of cells in normal physiological processes and in the context of disease such as inflammation, autoimmunity and cancer. Two major interactions are involved: (i) binding of chemokines to chemokine receptors, which activates the cellular machinery required for movement; and (ii) binding of chemokines to glycosaminoglycans (GAGs), which facilitates the organization of chemokines into haptotactic gradients that direct cell movement. Chemokines can bind and activate their receptors as monomers; however, the ability to oligomerize is critical for the function of many chemokines in vivo. Chemokine oligomerization is thought to enhance their affinity for GAGs, and here we show that it significantly affects the ability of chemokines to accumulate on and be retained by heparan sulfate (HS). We also demonstrate that several chemokines differentially rigidify and cross-link HS, thereby affecting HS rigidity and mobility, and that HS cross-linking is significantly enhanced by chemokine oligomerization. These findings suggest that chemokine–GAG interactions may play more diverse biological roles than the traditional paradigms of physical immobilization and establishment of chemokine gradients; we hypothesize that they may promote receptor-independent events such as physical re-organization of the endothelial glycocalyx and extracellular matrix, as well as signalling through proteoglycans to facilitate leukocyte adhesion and transmigration

Finite-Connectivity Spin-Glass Phase Diagrams and Low Density Parity Check Codes

We obtain phase diagrams of regular and irregular finite connectivity spin-glasses. Contact is firstly established between properties of the phase diagram and the performances of low density parity check codes (LDPC) within the Replica Symmetric (RS) ansatz. We then study the location of the dynamical and critical transition of these systems within the one step Replica Symmetry Breaking theory (RSB), extending similar calculations that have been performed in the past for the Bethe spin-glass problem. We observe that, away from the Nishimori line, in the low temperature region, the location of the dynamical transition line does change within the RSB theory, in comparison with the (RS) case. For LDPC decoding over the binary erasure channel we find, at zero temperature and rate R=1/4 an RS critical transition point located at p_c = 0.67 while the critical RSB transition point is located at p_c = 0.7450, to be compared with the corresponding Shannon bound 1-R. For the binary symmetric channel (BSC) we show that the low temperature reentrant behavior of the dynamical transition line, observed within the RS ansatz, changes within the RSB theory; the location of the dynamical transition point occurring at higher values of the channel noise. Possible practical implications to improve the performances of the state-of-the-art error correcting codes are discussed.Comment: 21 pages, 15 figure