Exchangeable Random Networks

We introduce and study a class of exchangeable random graph ensembles. They can be used as statistical null models for empirical networks, and as a tool for theoretical investigations. We provide general theorems that carachterize the degree distribution of the ensemble graphs, together with some features that are important for applications, such as subgraph distributions and kernel of the adjacency matrix. These results are used to compare to other models of simple and complex networks. A particular case of directed networks with power-law out--degree is studied in more detail, as an example of the flexibility of the model in applications.Comment: to appear on "Internet Mathematics

Preliminary evaluation of probiotic properties of Lactobacillus strains isolated from Sardinian dairy products

Twenty-three Lactobacillus strains of dairy origin were evaluated for some functional properties relevant to their use as probiotics. A preliminary subtractive screening based on the abilities to inhibit the growth of microbial pathogens and hydrolyze conjugated bile salts was applied, and six strains were selected for further characterization including survival under gastrointestinal environmental conditions, adhesion to gut epithelial tissue, enzymatic activity, and some safety properties. All selected strains maintained elevated cell numbers under conditions simulating passage through the human gastrointestinal tract, well comparable to the values obtained for the probiotic strain Lactobacillus rhamnosus GG, and were able to adhere to Caco-2 cells to various extents (from 3 to 20%). All strains exhibited high aminopeptidase, and absent or very low proteolytic and strong β-galactosidase activities; none was found to be haemolytic or to produce biogenic amines and all were susceptible to tetracycline, chloramphenicol, erythromycin, ampicillin, and amoxicillin/clavulanic acid. Our results indicate that the Lactobacillus strains analyzed could be considered appropriate probiotic candidates, due to resistance to GIT simulated conditions, antimicrobial activity, adhesion to Caco-2 cell-line, and absence of undesirable properties. They could be used as adjunct cultures for contributing to the quality and health related functional properties of dairy products

Metachronal wave and hydrodynamic interaction for deterministic switching rowers

We employ a model system, called rowers, as a generic physical framework to define the problem of the coordinated motion of cilia (the metachronal wave) as a far from equilibrium process. Rowers are active (two-state) oscillators interacting solely through forces of hydrodynamic origin. In this work, we consider the case of fully deterministic dynamics, find analytical solutions of the equation of motion in the long wavelength (continuum) limit, and investigate numerically the short wavelength limit. We prove the existence of metachronal waves below a characteristic wavelength. Such waves are unstable and become stable only if the sign of the coupling is reversed. We also find that with normal hydrodynamic interaction the metachronal pattern has the form of stable trains of traveling wave packets sustained by the onset of anti-coordinated beating of consecutive rowers.Comment: 11 pages, 7 figure

A vigorous activity cycle mimicking a planetary system in HD200466

Stellar activity can be a source of radial velocity (RV) noise and can reproduce periodic RV variations similar to those produced by an exoplanet. We present the vigorous activity cycle in the primary of the visual binary HD200466, a system made of two almost identical solar-type stars with an apparent separation of 4.6 arcsec at a distance of 44+/-2 pc. High precision RV over more than a decade, adaptive optics (AO) images, and abundances have been obtained for both components. A linear trend in the RV is found for the secondary. We assumed that it is due to the binary orbit and once coupled with the astrometric data, it strongly constrains the orbital solution of the binary at high eccentricities (e~0.85) and quite small periastron of ~21 AU. If this orbital motion is subtracted from the primary radial velocity curve, a highly significant (false alarm probability <0.1%) period of about 1300 d is obtained, suggesting in a first analysis the presence of a giant planet, but it turned out to be due to the stellar activity cycle. Since our spectra do not include the Ca~II resonance lines, we measured a chromospheric activity indicator based on the Halpha line to study the correlation between activity cycles and long-term activity variations. While the bisector analysis of the line profile does not show a clear indication of activity, the correlation between the Halpha line indicator and the RV measurements identify the presence of a strong activity cycle.Comment: Accepted on Astronomy and Astrophysics Main Journal 2014, 16 pages, 18 figure

Unethical practices within medical research and publication – An exploratory study

The data produced by the scientific community impacts on academia, clinicians, and the general public; therefore, the scientific community and other regulatory bodies have been focussing on ethical codes of conduct. Despite the measures taken by several research councils, unethical research, publishing and/or reviewing behaviours still take place. This exploratory study considers some of the current unethical practices and the reasons behind them and explores the ways to discourage these within research and other professional disciplinary bodies. These interviews/discussions with PhD students, technicians, and academics/principal investigators (PIs) (N=110) were conducted mostly in European higher education institutions including UK, Italy, Ireland, Portugal, Czech Republic and Netherlands. Through collegiate discussions, sharing experiences and by examining previously published/reported information, authors have identified several less reported behaviours. Some of these practices are mainly influenced either by the undue institutional expectations of research esteem or by changes in the journal review process. These malpractices can be divided in two categories relating to (a) methodological malpractices including data management, and (b) those that contravene publishing ethics. The former is mostly related to “committed bias”, by which the author selectively uses the data to suit their own hypothesis, methodological malpractice relates to selection of out-dated protocols that are not suited to the intended work. Although these are usually unintentional, incidences of intentional manipulations have been reported to authors of this study. For example, carrying out investigations without positive (or negative) controls; but including these from a previous study. Other methodological malpractices include unfair repetitions to gain statistical significance, or retrospective ethical approvals. In contrast, the publication related malpractices such as authorship malpractices, ethical clearance irregularities have also been reported. The findings also suggest a globalised approach with clear punitive measures for offenders is needed to tackle this problem

Meat quality and lipid fatty acid profile from wild thrush (Turdus philomelos), woodcock (Scolopax rusticola) and starling (Sturnus vulgaris): A preliminary comparative study

Background: The present study aimed to evaluate the nutritional proximate composition, some qualitative traits and fatty acid profile of meat from wild thrush, woodcock and starling hunted in Southern Italy in 2017 and 2018. Methods: Nutritive composition and physical traits of meat and lipid fatty acid profile were evaluated in breast muscle (Pectoralis major) of gamebirds. Results: From findings, the meat pH was significantly (P &lt; 0.001) higher in starling when compared to the other two species. Thrush meat was significantly (P = 0.002) darker and had higher redness (P &lt; 0.001) and yellowness (P = 0.004) in comparison to starling and woodcock. Thrush breast muscle showed the highest (P &lt; 0.001) level of lipids and lowest (P &lt; 0.001) protein content. Meat from thrush showed the best lipid fatty acid profile based on the higher (P &lt; 0.001) monounsaturated fatty acids (MUFA) and lower (P &lt; 0.001) saturated fatty acids (SFA) concentrations. Starling breast muscle reported the highest (P = 0.002) polyunsaturated fatty acids (PUFA) level compared to both thrush and woodcock, whereas no differences were detected on total n-3. The ratio n-6/n-3 was higher (P = 0.001) in starling muscle. Thrush breast muscle had the lowest (P &lt; 0.001) atherogenic and thrombogenic indices compared to the other gamebirds. Conclusions: The findings indicated that meat from the three investigated gamebirds species may represent a healthily lipid food source for human consumption in relation to the prevention of cardiovascular diseases

Knee stability, athletic performance and sport-specific tasks in non-professional soccer players after ACL reconstruction: comparing trans-tibial and antero-medial portal techniques.

Background: a wrong position of bone tunnels, in particular on the femur, is one of the most frequent causes of a failed anterior cruciate ligament (ACL) reconstruct ion. Several studies demonstrated that drilling the femoral tunnel through the antero-medial portal (AMP) allows a more anatomical placement on the lateral femoral condyle and higher knee stability, compared to trans-tibial (TT) technique. The aim of this study was to retrospectively evaluate two groups of soccer players operated on for ACL reconstruction according to either one of these two techniques. Methods: two groups of non-professional soccer players operated on for a single bundle ACL reconstruction with hamstrings autograft using either a TT (20 patients) or an AMP (23 patients) technique were retrospectively evaluated with KT- 1000 arthrometer, manual pivot shift test, isokinetic test, the incremental treadmill-running test, athletic and sport specific tasks, and knee scores (IKDC, Lysholm and KOOS). Results: the AMP group showed better results at pivot shift test and KOOS, but lower flexion angles at single leg squat test. There were no differences in all the other considered outcomes. Conclusions: the better rotational stability of the knee achieved in AMP group did not lead to significantly better clinical and functional results in our patients. Level of evidence III. Treatment study: Case-control study