Truncated moments of parton distributions

We derive evolution equations satisfied by moments of parton distributions when the integration over the Bjorken variable is restricted to a subset (x_0 <= x <= 1) of the allowed kinematical range 0<= x<= 1. The corresponding anomalous dimensions turn out to be given by a triangular matrix which couples the N--th truncated moment with all (N + K)--th truncated moments with integer K >= 0. We show that the series of couplings to higher moments is convergent and can be truncated to low orders while retaining excellent accuracy. We give an example of application to the determination of alpha_s from scaling violations.Comment: 11 pages, no figures, latex. Final version, to be published in Phys. Lett. B. A few typos corrected; derivation of eq.(9) improve

Excitation of travelling multibreathers in anharmonic chains

We study the dynamics of the "externally" forced and damped Fermi-Pasta-Ulam (FPU) 1D lattice. The forcing has the spatial symmetry of the Fourier mode with wavenumber p and oscillates sinusoidally in time with the frequency omega. When omega is in the phonon band, the p-mode becomes modulationally unstable above a critical forcing, which we determine analytically in terms of the parameters of the system. For omega above the phonon band, the instability of the p-mode leads to the formation of a travelling multibreather, that, in the low-amplitude limit could be described in terms of soliton solutions of a suitable driven-damped nonlinear Schroedinger (NLS) equation. Similar mechanisms of instability could show up in easy-axis magnetic structures, that are governed by such NLS equations.Comment: To appear in Physica D (2002

Are Parton Distributions Positive?

We show that the naive positivity conditions on polarized parton distributions which follow from their probabilistic interpretation in the naive parton model are reproduced in perturbative QCD at the leading log level if the quark and gluon distribution are defined in terms of physical processes. We show how these conditions are modified at the next-to-leading level, and discuss their phenomenological implications, in particular in view of the determination of the polarized gluon distributionComment: 5 pages, 4 figures, latex with espcrc2 and epsfi

Metabolic syndrome and cardiovascular risk after liver transplantation: a single-center experience.

Excessive weight gain, hypertension, hyperlipidemia, and diabetes are frequently observed among orthotopic liver transplantation (OLT) patients. These alterations, which are probably multifactorial in origin, contribute to posttransplantation metabolic syndrome (PTMS), which increases the risk of cardiovascular events. We assessed the prevalence of PTMS (diagnosed according to modified NCEP Adult Treatment Panel III criteria) in 156 OLT patients undergoing regular follow-up after transplantation (median 68 months; range, 6 to 234 months). Several pre- and post-OLT data were collected to identify the factors associated with the presence of PTMS which was found in 28% of cases. The only independent predictive factors for PTMS were diabetes mellitus and patients who were overweight or obese before-OLT. The prevalence of PTSM was lower among patients on tacrolimus immunosuppression. In our population, 21% of patients showed a high cardiovascular risk score with a 4% incidence of cardiovascular events, which was higher among subjects with PTMS. Close follow-up is mandatory to prevent the development of PTMS mainly among overweight and diabetic patients before transplantation

Charge-Modulated Field-Effect Transistor: technologies and applications for biochemical sensing

The research activity described in the attached dissertation focused on the development, fabrication and characterization of field-effect transistor-based biochemical sensor (bioFET) developed in different technologies. Such a research field has been attracting a significant interest in the last decades, as electronic sensors can represent as valuable, portable and low cost alternative to the bulk, expensive laboratory instrumentation. Among the biochemical reactions, genetic processes have been thoroughly investigated in literature: in particular, DNA hybridization detection represents a basic biological reaction for several, more sophisticated analysis in medical, pharmaceutical and forensic fields. The development of the research activity was centered on a specific biosensor, namely Charge-Modulated Field-Effect Transistor (CMFET), originally proposed in 2005 by the Electronic Department at the University of Cagliari. In particular, the aim of the activity was to make a significant step forward with respect to the results already presented in literature for DNA hybridization detection, employing two different technologies: CMOS process and organic electronics. As regards CMOS process, the activity mainly focused on the testing of a Lab-on-a-Chip (LoC), hosting several CMFET structures, developed and fabricated before but never tested. The activity carried out allowed to develop a precise electrical model of the device, validated by actual measurements, by which the basic performances of the device were derived. Subsequently, the application of the LoC for DNA hybridization detection was demonstrated: a reliable biochemical protocol for the modification of the chip surface with DNA strands was developed, as well as a precise measurement procedure. A complete evaluation of the sensitivity and selectivity of the device with respect to DNA hybridization was obtained; from the obtained results, several consideration about the relationship between the chip layout and the performances of the device were inferred. In conclusion, a road-map for the development of a new chip, customized for the application as DNA hybridization sensor, was developed. As regards the Organic CMFET (OCMFET), the activity comprised design, fabrication and testing of devices particularly conceived as disposable DNA hybridization sensors for field-measurement kits. Such a task required the development of innovative technological processes for the fabrication of high-performances organic transistors, i.e. transistors capable to be operated at low voltages (about 1 V) with quasi-ideal electrical performances. In particular, a highly reliable fabrication process, compatible with plastic electronics and easily up-scalable to an industrial size, was determined. Consequently, novel OCMFET were fabricated and tested. World record results in terms of sensitivity and selectivity among the organic transistor-based DNA sensors were reproducibly obtained. Thanks to the reliability of the results, the performances of the OCMFET were carefully studied, and design rules for the optimization of the device were inferred; an optimized, low voltage OCMFET allowed to further enhance the result, determining final performances even better than the one of silicon-based sensors. Finally, thanks to an innovative analysis on the influence of the device polarization to the characteristics of the bioreceptor layer at a micro-nanometrical size, a physical effect related to a tilting of the DNA molecules with respect to the surface was observed. This feature, possibly related to the CMFET working principle, can allow to overcome a general limitation of the bioFET technologies that have limited so far the application of these devices in vivo, thus opening novel possible applications for the CMFET working principle beyond the measurements in vitr

Cross sectional study on the variation of plaque pH in diabetic patients: a clinical randomized trial on the capability of Probiotic (<i>Lactobacillus Brevis</i> CD2) to reduce plaque acidogenicity in a sample of diabetic children

Objective: The aim of this study was to evaluate the difference in caries experience and different caries-related variables between diabetic and non-diabetic children aged 5-13 years old. A further analysis was carried out on diabetic children after they were divided in two groups based on their metabolic control. Material and Methods: We designed a case-control study on two categories of children: the first group consisted of 68 children diagnosed with type 1 diabetes and the second group consisted of 136 non-diabetic control children. The diabetic children were then divided into two subgroups: a) 20 children with adequate metabolic control (Hb1ac≤7.5) and b) 48 children with poor metabolic control (Hb1ac&gt;7.5). Data on dietary and oral hygienic habits was obtained on all the subjects participating in the study. Collection of saliva was carried out after stimulating salivation by chewing on a piece of paraffin for 5 minutes. Microbial flora was analyzed using the checkerboard DNA-DNA hybridisation method. Plaque acidogenity was recorded using pH indicator strips up to 30 min after a sucrose rinse. Caries registration was performed using the ICDAS index. Results: No statically significant difference in clinical data was found in the two study groups with similar caries status. No statistically significant difference was found for tooth brushing frequency, use of fluoridated toothpaste, mouthwash and other fluoride supplements and the pattern of dental check-ups between the groups examined. Statistically significant differences for plaque-pH when analyzed as minimum pH, AUC6.2 and AUC5.7 between all diabetic and the non-diabetic children (p&lt;0.01 or p&lt;0.05) were found. The bacterial counts differed significantly between diabetic and non-diabetic subjects regarding S. Mutans, S. Sobrinus, L. Salivarius and L. Fermentum (p&lt;0.05). Conclusions: Type 1 Diabetes Mellitus patients showed a more cariogenic bacterial environment and a direct effect on plaque pH reducing it from normal levels was detected

Platelet-to-lymphocyte ratio in the setting of liver transplantation for hepatocellular cancer. A systematic review and meta-analysis

AIM: To perform a systematic review and meta-analysis on platelet-to-lymphocyte ratio (PLR) as a risk factor for post-transplant hepatocellular cancer (HCC) recurrence. METHODS: A systematic literature search was performed using PubMed. Participants of any age and sex, who underwent liver transplantation for HCC were considered following these criteria: (1) studies comparing pre-transplant low vs high PLR values; (2) studies reporting post-transplant recurrence rates; and (3) if more than one study was reported by the same institute, only the most recent was included. The primary outcome measure was set for HCC recurrence after transplantation. RESULTS: A total of 5 articles, published between 2014 and 2017, fulfilled the selection criteria. As for the quality of the reported studies, all the investigated articles presented an overall high quality. A total of 899 cases were investigated: 718 cases (80.0%) were males. Three studies coming from European countries and one from Japan presented HCV as the main cause of cirrhosis. On the opposite, one Chinese study presented a greater incidence of HBV-related cirrhotic cases. In all the studies apart one, the PLR cut-off value of 150 was reported. At meta-analysis, high PLR value was associated with a significant increase in recurrence after transplantation (OR = 3.33; 95%CI: 1.78-6.25; p &lt; 0.001). A moderate heterogeneity was observed among the identified studies according to the Higgins I 2 statistic value. CONCLUSION: Pre-transplant high PLR values are connected with an increased risk of post-operative recurrence of hepatocellular cancer. More studies are needed for better clarify the biological mechanisms of this results

Gli ISSR (Inter Simple Sequence Repeats) come strumento molecolare per l'identificazione tassonomica di ciprinodontiformi mediterranei

Il genere Valencia (Valenciidae) ha una distribuzione disgiunta, con V. hispanica presente in habitat dulciacquicoli o leggermente salmastri dalla Catalogna meridionale all'estremità meridionale del Golfo di Valencia e V. letourneuxi segnalata nell'Albania meridionale e nella Grecia occidentale. Nel presente lavoro sono stati analizzati e confrontati i profili ISSR dei seguenti esemplari: 2 pesci di dubbia collocazione tassonomica, provenienti da una popolazione mantenuta in cattività da un allevatore amatoriale danese di pesci da acquario, 2 individui di V. hispanica, 5 di V. letourneuxi e 5 dell'altro ciprinodontiforme Aphanius fasciatus. Lo scopo del lavoro è stato quello di 1) saggiare l'efficacia degli ISSR nel risolvere problemi di tipo tassonomico e 2) verificare l'ipotesi di appartenenza dei due esemplari di dubbia collocazione tassonomica ad una delle due specie di Valencia. L'estrazione del DNA è stata effettuata mediante kit di estrazione, utilizzando porzioni di pinna caudale (circa 5 mg ciascuna) fissate in etanolo. Sono stati utilizzati 9 primer che hanno fornito complessivamente 101 loci. Il confronto dei profili ISSR, e l'analisi dei cluster basata sulla matrice delle dissimilarità di Rogers e Tanimoto hanno consentito di assegnare gli individui di dubbia identità a V. hispanica. Gli ISSR si sono rivelati uno strumento efficace per la risoluzione di problemi di tipo tassonomico