Studies of the performance of different front-end systems for flat-panel multi-anode PMTs with CsI(Tl) scintillator arrays

We have studied the performance of two different types of front-end systems for our gamma camera based on Hamamatsu H8500 (flat-panel 64 channels multi-anode PSPMT) with a CsI(Tl) scintillator array. The array consists of 64 pixels of $6\times6\times20{\rm mm}^3$ which corresponds to the anode pixels of H8500. One of the system is based on commercial ASIC chips in order to readout every anode. The others are based on resistive charge divider network between anodes to reduce readout channels. In both systems, each pixel (6mm) was clearly resolved by flood field irradiation of $^{137}$Cs. We also investigated the energy resolution of these systems and showed the performance of the cascade connection of resistive network between some PMTs for large area detectors.Comment: 9 pages, 6 figures, proceedings of the 7th International Workshop on Radiation Imaging Detectors (IWORID7), submitted to NIM

Prediction of late/early arrivals in container terminals - A qualitative approach

Vessel arrival uncertainty in ports has become a very common problem worldwide. Although ship operators have to notify the Estimated Time of Arrival (ETA) at predetermined time intervals, they frequently have to update the latest ETA due to unforeseen circumstances. This causes a series of inconveniences that often impact on the efficiency of terminal operations, especially in the daily planning scenario. Thus, for our study we adopted a machine learning approach in order to provide a qualitative estimate of the vessel delay/advance and to help mitigate the consequences of late/early arrivals in port. Using data on delays/advances at the individual vessel level, a comparative study between two transshipment container terminals is presented and the performance of three algorithmic models is evaluated. Results of the research indicate that when the distribution of the outcome is bimodal the performance of the discrete models is highly relevant for acquiring data characteristics. Therefore, the models are not flexible in representing data when the outcome distribution exhibits unimodal behavior. Moreover, graphical visualisation of the importance-plots made it possible to underline the most significant variables which might explain vessel arrival uncertainty at the two European ports

Effect of dietary chitosan on haematology, innate immunity and disease resistance of Asian seabass Lates calcarifer (Bloch).

This study was performed to evaluate the effect of dietary chitosan on haematology, innate immunity and protection against Vibrio anguillarum in Asian seabass, Lates calcarifer. A basal diet supplemented with 0, 5, 10 and 20 g chitosan kg−1 diet was fed to the four different groups for 60 days. The haematological (total erythrocyte count, total leucocyte count, total serum protein, albumin, globulin and albumin‐globulin ratio) and innate immune parameters (phagocytic ratio, respiratory burst, serum lysozyme and serum bactericidal activities) were monitored at fortnight interval to assess the effect of chitosan feeding in Asian seabass. All the studied haematological and innate immune parameters were increased significantly (P ≤ 0.05) in chitosan‐fed groups in comparison with control. However, the group fed diet containing 10 g chitosan Kg−1 feed showed highest haematological and innate immune parameters on 45th day in comparison with other groups. Moreover, the fish fed the diet containing 10 g chitosan Kg−1 feed had significantly higher post‐challenge survival (75.56 ± 4.44%) on the 30th day following V. anguillarum challenge. Therefore, this study suggests that chitosan at 10 g kg−1 diet could be used as prophylactic in Asian seabass culture to enhance the protection against any possible infection by V. anguillarum

Impact of reimbursement limits on patient access to direct-acting antivirals in Italy: Analysis of data from national registries

OBJECTIVE: Hepatitis C virus (HCV) infection is a global epidemic, still highly prevalent in Europe. Given efficacy and safety of HCV therapy by Direct Antiviral Agents (DAA), World Health Organization called for actions to eliminate HCV infection. A limit is represented by access to care, mostly due to the high costs of medicines. In Italy, in 2015, the access to DAA therapy was reimbursed for patients with advanced disease, whereas in 2017 universal access was granted. The aim of this study was to analyse changes in patient recruitment trends treated with DAA with or without limitations to access to therapy. PATIENTS AND METHODS: 165,105 patients treated with DAA in Italy from 2015 to December 2018 were analysed. Daily patient treatment rate was obtained by segmented regression of interrupted time series analysis. RESULTS: 74,199 patients with advanced disease (62% with cirrhosis) had access to the therapy during the time period from 2015 to 2017. Following the extension of reimbursement criteria, 90,906 additional patients were treated (43.2% with F0-F1 and 22.9% with F2), with an absolute reduction of 59.9% of patients with advanced disease (cirrhosis decreased to 18.5%). Segmented regression of interrupted time series analysis of daily patient treatment rate showed a progressive reduction of patients with advanced disease, offset by those with initial disease. Notably, elimination of restrictions to therapy did not change the overall treatment rate. CONCLUSIONS: This study showed that a no-limit reimbursement policy for DAAs prescriptions to HCV infected individuals in Italy widened the types of treated patients, but the process towards elimination of HCV infection was not significantly changed

Development of Large area Gamma-ray Camera with GSO(Ce) Scintillator Arrays and PSPMTs

We have developed a position-sensitive scintillation camera with a large area absorber for use as an advanced Compton gamma-ray camera. At first we tested GSO(Ce) crystals. We compared light output from the GSO(Ce) crystals under various conditions: the method of surface polishing, the concentration of Ce, and co-doping Zr. As a result, we chose the GSO(Ce) crystals doped with only 0.5 mol% Ce, and its surface polished by chemical etching as the scintillator of our camera. We also made a 16$\times$16 cm$^2$ scintillation camera which consisted of 9 position-sensitive PMTs (PSPMTs Hamamatsu flat-panel H8500), the each of which had 8$\times$8 anodes with a pitch of 6 mm and coupled to 8$\times$8 arrays of pixelated 6$\times6\times$13 mm$^3$ GSO(Ce) scintillators. For the readout system of the 576 anodes of the PMTs, we used chained resistors to reduce the number of readout channels down to 48 to reduce power consumption. The camera has a position resolution of less than 6mm and a typical energy resolution of 10.5% (FWHM) at 662 keV at each pixel in a large area of 16$\times$16 cm$^2$. %to choose the best scintillator for our project. Furthermore we constructed a 16$\times$16 array of 3$\times3\times$13 mm$^3$ pixelated GSO(Ce) scintillators, and glued it to a PMT H8500. This camera had the position resolution of less than 3mm, over an area of 5$\times$5 cm$^2$, except for some of the edge pixels; the energy resolution was typically 13% (FWHM) at 662 keV.Comment: Proceedings of PSD7 appear in NIM

Signatures of non-gaussianity in the isocurvature modes of primordial black hole dark matter

Primordial black holes (PBHs) are black holes which may have formed very early on during the radiation dominated era in the early universe. We present here a method by which the large scale perturbations in the density of primordial black holes may be used to place tight constraints on non-gaussianity if PBHs account for dark matter (DM). The presence of local-type non-gaussianity is known to have a significant effect on the abundance of primordial black holes, and modal coupling from the observed CMB scale modes can significantly alter the number density of PBHs that form within different regions of the universe, which appear as DM isocurvature modes. Using the recent \emph{Planck} constraints on isocurvature perturbations, we show that PBHs are excluded as DM candidates for even very small local-type non-gaussianity, $|f_{NL}|\approx0.001$ and remarkably the constraint on $g_{NL}$ is almost as strong. Even small non-gaussianity is excluded if DM is composed of PBHs. If local non-Gaussianity is ever detected on CMB scales, the constraints on the fraction of the universe collapsing into PBHs (which are massive enough to have not yet evaporated) will become much tighter.Comment: 23 pages, 11 figures. V2: minor corrections and changes, matches published versio

Geodetic precession and strong gravitational lensing in the dynamical Chern-Simons modified gravity

We have investigated the geodetic precession and the strong gravitational lensing in the slowly-rotating black hole in the dynamical Chern-Simons modified gravity theory. We present the formulas of the orbital period $T$ and the geodetic precession angle $\Delta\Theta$ for the timelike particles in the circular orbits around the black hole, which shows that the change of the geodetic precession angle with the Chern-Simons coupling parameter $\xi$ is converse to the change of the orbital period with $\xi$ for fixed $a$. We also discuss the effects of the Chern-Simons coupling parameter on the strong gravitational lensing when the light rays pass close to the black hole and obtain that for the stronger Chern-Simons coupling the prograde photons may be captured more easily, and conversely, the retrograde photons is harder to be captured in the slowly-rotating black hole in the dynamical Chern-Simons modified gravity. Supposing that the gravitational field of the supermassive central object of the Galaxy can be described by this metric, we estimated the numerical values of the main observables for gravitational lensing in the strong field limit.Comment: 19 pages, 5 figures, more clarifications and references added, accepted for publication in Classical and Quantum Gravit

Acoustic horizons for axially and spherically symmetric fluid flow

We investigate the formation of acoustic horizons for an inviscid fluid moving in a pipe in the case of stationary and axi-symmetric flow. We show that, differently from what is generally believed, the acoustic horizon forms in correspondence of either a local minimum or maximum of the flux tube cross-section. Similarly, the external potential is required to have either a maximum or a minimum at the horizon, so that the external force has to vanish there. Choosing a power-law equation of state for the fluid, $P\propto \rho^{n}$, we solve the equations of the fluid dynamics and show that the two possibilities are realized respectively for $n>-1$ and $n<-1$. These results are extended also to the case of spherically symmetric flow.Comment: 6 pages, 3 figure