Application of novel techniques for interferogram analysis to laser-plasma femtosecond probing

Recently, two novel techniques for the extraction of the phase-shift map (Tomassini {\it et.~al.}, Applied Optics {\bf 40} 35 (2001)) and the electronic density map estimation (Tomassini P. and Giulietti A., Optics Communication {\bf 199}, pp 143-148 (2001)) have been proposed. In this paper we apply both methods to a sample laser-plasma interferogram obtained with femtoseconds probe pulse, in an experimental setup devoted to laser particle acceleration studies.Comment: Submitted to Laser and Particle Beam

A Molecular Dynamics Study of Noncovalent Interactions between Rubber and Fullerenes

The percolation and networking of filler particles is an important issue in the field of rubber reinforcement, and much effort is given to clarify the true nature of the reinforcement mechanism and the viscoelastic behavior. The concentration of nanofillers also in the presence of large amounts of carbon black is a parameter that can influence the macroscopic rubber behavior. In this paper, noncovalent interactions between C60 fullerenes with poly-1,4-cis-isoprene (PI) either as such or modified are studied through atomistic simulations based on molecular mechanics (MM) and molecular dynamics (MD) methods. At first, the conformational properties of a single chain and of 12 PI chains in a periodic simulation box are studied. Afterwards, the conformational properties of a single PI chain polymer terminated with a -COOH group, and then a bulk system formed by chains of unmodified and some PI modified chains are considered. Then, the systems formed by adding fullerenes to these two different bulk systems are studied. Relatively small interaction energy between rubber and fullerenes being well dispersed in the sample is found. The simulations showed a preferential tendency of fullerenes to display self-aggregation, in the presence of even a small fraction of modified polymer chains

Hardware-Software Co-Design of BIKE with HLS-Generated Accelerators

In order to mitigate the security threat of quantum computers, NIST is undertaking a process to standardize post-quantum cryptosystems, aiming to assess their security and speed up their adoption in production scenarios. Several hardware and software implementations have been proposed for each candidate, while only a few target heterogeneous platforms featuring CPUs and FPGAs. This work presents a HW/SW co-design of BIKE for embedded platforms featuring both CPUs and small FPGAs and employs high-level synthesis (HLS) to timely deliver the hardware accelerators. In contrast to state-of-the-art solutions targeting performance-optimized HLS accelerators, the proposed solution targets the small FPGAs implemented in the heterogeneous platforms for embedded systems. Compared to the software- only execution of BIKE, the experimental results collected on the systems-on-chip of the entire Xilinx Zynq-7000 family highlight a performance speedup ranging from 1.37x, on Z-7010, to 2.78x, on Z-7020

Polyether from a biobased Janus molecule as surfactant for carbon nanotubes

A new polyether (PE) was prepared from a biobased Janus molecule, 2-(2,5-dimethyl-1H-pyrrol-1-yl)-1,3- propanediol (serinol pyrrole, SP). SP was synthesized with very high yield (about 96%) and high atom efficiency (about 80%) by reacting a biosourced molecule, such as serinol, with 2,5-hexanedione in the absence of solvent or catalyst. The reaction of SP with 1,6-dibromohexane led to PE oligomers, that were used as surfactants for multiwalled carbon nanotubes (MWCNT), in ecofriendly polar solvents such as acetone and ethyl acetate. The synergic interaction of aromatic rings and oxyalkylene sequences with the carbon allotrope led to dramatic improvement of surfactant efficiency: only 24% of SP based PE was extracted with ethyl acetate from the adduct with MWCNT, versus 98% of a typical pluronic surfactant. Suspensions of MWCNT-PE adducts in ethyl acetate were stable for months. High resolution transmission electron microscopy revealed a film of oligomers tightly adhered to MWCNT surface

Dynamics of charge-displacement channeling in intense laser-plasma interactions

The dynamics of transient electric fields generated by the interaction of high intensity laser pulses with underdense plasmas has been studied experimentally with the proton projection imaging technique. The formation of a charged channel, the propagation of its front edge and the late electric field evolution have been characterised with high temporal and spatial resolution. Particle-in-cell simulations and an electrostatic, ponderomotive model reproduce the experimental features and trace them back to the ponderomotive expulsion of electrons and the subsequent ion acceleration.Comment: 5 figures, accepted for publication in New Journal of Physic

Experimental study of picosecond laser plasma formation in thin foils

A high performance, fully controlled picosecond laser system has been designed and built with the aid of a numerical code capable of simulating the temporal behavior of the laser system, including each active and passive component. The laser performance was characterized with an optical streak camera, equivalent plane monitor, and calorimeter measurements. The laser pulse was focused on 150-nm thick foils to investigate plasma formation and the related transmittivity of the laser light. The experimental data are in very good agreement with the predictions of a simple, 2D analytical model that takes into account the actual shot-to-shot features of the laser pulse. The temporal profile of the pulse and the intensity distribution in the focal spot were found to play a key role in determining the transmission properties of the laser-irradiated foil. This work may be relevant to a wide class of laser exploded foil plasma experiments

Teachers’ stress experiences during COVID-19-related emergency remote teaching: Results from an exploratory study

The study provides a portrait of teachers’ stress experience in the face of the needed introduction of information systems (IS) during COVID-19-related emergency remote teaching. Researchers contacted the headmasters at several Italian schools, who choose teacher’s representatives. The latters shared the online questionnaire among colleagues; the teachers voluntarily decided to participate. The cross-sectional study involved 237 Italian teachers (81.5% female; Mage = 50.20; SDage = 8.87). This survey wanted to detect information systems-related distress and eustress on the job, and technostress creators and inhibitors. Descriptive statistics, correlational analyses, and a multiple regression model using structural equation modeling were run. As according to the model, IS-related distress and eustress on the job were the dependent variables, technostress creators and inhibitors the independent ones, and respondents’ gender and age the control ones. Both technostress creators and inhibitors showed significant relationships with IS-related distress and eustress. Technostress creators showed a positive relationship with IS-related distress and a negative one with IS-related eustress; conversely, technostress inhibitors showed an opposite pattern of relationships. Only technostress creators significantly associate to both age and gender in the model, suggesting that older, female teachers tended to experience more technostress creators. Due to the increases in remote work, the awareness of IS-related stress experiences represents a key factor to evaluate work-related risks and prevent stress-related problems. The results from this study suggest that using technologies can represent both a threat to one’s well-being, highlighting the need to provide adequate trainings and support, but also a resource for personal enrichment