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Background: Brain functions arise from the orchestrated activation and cooperation of networks of regions whose specific relationship varies dynamically across functional states. Resting state functional Magnetic Resonance Imaging (RS-fMRI) analyses focuses on spontaneous low frequency fluctuations (< 0.1 Hz) in the BOLD signal and investigates synchronous activations between regions that are spatially distinct (functional connectivity, FC), occurring in the absence of a task or stimulus. Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation technique that is known to modulate cortical activity and FC among brain regions, as measured by functional Magnetic Resonance Imaging. It is well established that motor response (motor evoked potentials, MEP) is enhanced by anodal tDCS stimulation and reduced after catodal tDCS stimulation, for a period of about 5 minutes. Further studies showed different patterns of FC modulation after tDCS, depending on polarity but also on the regions studied, but little is known about the duration of the effect. Aim: this study aimed to measure the variation of functional connectivity between cortical brain regions after tDCS along time. Methods: For this purpose we enrolled 30 healthy right-handed subjects. All subjects underwent 4 sessions RS-fMRI (10’each, TR 2’’, 300 volumes, 1.5T scanner): 2 immediately before and 2 after 20’ tDCS over left M1. 20 of them received real (anodal) tDCS, 10 received sham stimulation. Data from 6 subjects (5 real, 1 sham) have been excluded for movement artifacts or other technical problems. We analyzed FC between left and right M1 with two different statistical analyses: Seed-based Correlation Analysis (SCA) and the Temporal Concatenation Group ICA (TC-GICA). Results: Seed-based Correlation Analysis showed a significant decrease of FC during the first fMRI acquisition immediately after anodal tDCS stimulation (p=0.005), that got back to baseline during the last fMRI session. This behavior was not found in subjects who underwent sham stimulation (p=0.12). The Temporal Concatenation Group ICA (TC-GICA) showed that immediately after anodal stimulation the average value of voxels decreases significantly (p

Alongside with the development of Neutron Capture Therapy (NCT) and the use of thermal neutrons for radiotherapeutic purposes, many efforts have been devoted to the characterization of the beam in order to optimize therapy procedures. Reliable dose measurements should be able to determine the various (neutrons and photonic) components of the mixed beam usually employed for therapy. This paper studies the effect of additives such as Boric and Gadolinium nuclei on the sensitivity of neutron organic (alanine and ammonium tartrate) dosimeters analyzed through Electron Spin Resonance (ESR) technique. These dosimeters were exposed to a mixed (neutron-gamma) field mainly composed of thermal neutrons. The choice of 10B and 64Gd as nuclei additives is due to their very high capture cross section for thermal neutrons. Also, after the nuclear reaction with thermal neutrons are emitted particles, which in turn release their energy in the vicinity of the reaction site. The irradiation with mixed (neutron-gamma) field were performed within the thermal column of the TRIGA reactor, University of Pavia. Dosimeters readout was performed through the Electron Spin Resonance (ESR) spectrometer Bruker ECS106 located at the Laboratory of Dosimetry ESR / TL of the Department of Physics and Chemistry - University of Palermo. We found that the addition of Gadolinium allows to largely increase the sensitivity of the dosimeters for thermal neutrons. In particular, a low concentration (5% by weight) of gadolinium oxide leads to an improvement of the sensitivity of neutrons more than 10 times. In addition, for this low content of gadolinium the photon tissue equivalence is not heavily reduced. This experimental analyses are compared with computational analyses carried out by means of Monte Carlo simulations performed with the MCNP (Monte Carlo N-Particle) transport code. A good agreement was observed for alanine dosimeters.

The development of Neutron Capture Therapy (NCT) for cancer treatments has stimulated the research for beam characterization in order to optimize the therapy procedures. The NCT has found to be promising for treatments of tumours which hardly can be treated with other techniques, such as gliomas. Alongside with the improvements of this technique, the development of procedures for the beam characterization arouses great interest in order to optimize the therapy protocol by reliably determining the various (neutronic and photonic) components of the mixed beam usually employed for therapy. Electron Paramagnetic Resonance (EPR) dosimetry for electron and photon beams with alanine has attracted the attention of many research groups for dosimetric purposes. Furthermore, the applications of EPR dosimetry for high LET radiation beams, such as carbon ions and neutrons, are continuously increasing. This is because of the very good dosimetric features of alanine EPR detectors such as: tissue equivalence for photon beams, linearity of its dose-response over a wide range, high stability of radiation induced free radicals, no destructive read-out procedure, no need of sample treatment before EPR signal measurement and low cost of the dosimeters. Moreover, in order to improve the sensitivity to thermal neutrons of alanine dosimeters the addition of nuclei such as gadolinium oxidewas previously studied. The choice of Gd as additive nucleus is due to its very high capture cross section to thermal neutrons and to the possibility for secondary particles produced after interaction with thermal neutrons of releasing their energy in the neighbourhood of the reaction site. In particular, it was found that low concentration (i.e. 5% by weight) of gadolinium oxide brings about an neutron sensitivity enhancement of more than 10 times without heavily reducing tissue equivalence. We have studied the response of alanine pellets with and without gadolinium exposed to the thermal column of the TRIGA Mark II research reactor at the University of Mainz. Pure alanine dosimeters used were produced by Synergy Health (Germany) whereas the Gd-added dosimeters were produced at the University of Palermo. The irradiations were performed inside polyethylene holders to guarantee charged particles equilibrium conditions. The results of EPR experiments are compared to Monte Carlo (MC) simulations aimed at obtaining information about the contribution of the various components to the total dose measured by means of EPR dosimeters. For alanine dosimeters a good agreement between experimental data and MC simulation have been achieved.

Limestone, used in artistic and architectural fields because of its composition and textural characteristics, is particularly susceptible to decay. Its constant exposure to a combination of weathering factors, causes an increase in porosity and a loss of material cohesion. In order to deal with this deterioration process, Ca(OEt)2 as a novel product developed during the EC NANOMATCH project, is tested to consolidate four types of limestone widely employed within Italian Cultural Heritage: Noto stone, Lecce stone, Carrara marble and Vicenza stone [1]. Pore-space properties, such as pore-size distribution and connected porosity, are crucial factors in the evaluation of a consolidation product and, throughout this study, they are analysed with NMR relaxometry of water 1H nuclei. This technique, being both non-destructive and non-invasive, is able to obtain both longitudinal (T1) and transverse (T2) relaxation time distributions of water in the stones' pores, before and after the consolidation treatment [2]. The results demonstrate that T2 is more sensitive than T1 in detecting pores of small dimension for all lithotypes, but not for marble which gives results that are not easily legible due to its low open porosity and a small quantity of absorbed water. Combining relaxation data and micro-structural studies performed by MIP and SEM measurements, a better understanding is obtained of the changes within stone porosity. The results confirm that NMR technique could be a useful tool for the evaluation of consolidation treatment on stone.