An electron beam, characterized by a high-angular discrimination (≃0.7°), has been used to measure the total (elastic plus inelastic) cross section of H2O in the energy range 3–100 eV. Broad ...coincidence is found with recent experiments, including a pronounced shoulder in the 6–12 eV region. However, at energies ≲6 eV, the present cross sections are ≃30% higher. Furthermore, forward scattering has been probed in the angular range 0°–3.5° and measures of the average (rotationally and vibrationally summed) differential elastic cross sections for incident energies ≤12 eV are obtained at a scattering angle ≃1∘. The measurements, which provide the first test of theoretical predictions in an angular region experimentally unexplored until now, are found to be within 1 standard deviation of corresponding ab initio R-matrix calculations.
Quantum physics is undoubtedly the most successful theory of the microscopic world, yet the complexities which arise in applying it even to simple atomic and molecular systems render the description ...of basic collision probabilities a formidable task. For this reason, approximations are often employed, the validity of which may be restricted to given energy regimes and/or targets and/or projectiles. Now we have found that the lognormal function, widely used for the probability distribution of macroscopic stochastic events (as diverse as periods of incubation of and recovery from diseases, size of grains, abundance of species, fluctuations in economic quantities, etc.) may also be employed to describe the energy dependence of inelastic collisions at the quantum level (including ionization, electron capture and excitation by electrons, positrons, protons, antiprotons, etc.), by allowing for the relevant threshold energy. A physical interpretation is discussed in this article by analogy with the heat capacity of few-level systems in solid state physics. We find the generality of the analysis to extend also to nuclear reactions. As well as aiding the description of collision probabilities for quantum systems, this finding is expected to impact also on the fundamental understanding of the interface between the classical and quantum domains.
An electrostatic beam has been used to perform scattering measurements with an angular-discrimination of . The total cross sections of positrons scattering from helium and krypton have been ...determined in the energy range (10-300) eV. This work was initially stimulated by the investigations of Nagumo et al (2011 J. Phys. Soc. Japan 80 064301), the first positron field-free measurements performed with a similarly high resolution, which found significant discrepancies at low energies with most other experiments and theories. The present results show good agreement with theories and several other measurements, even those characterized by a much poorer angular discrimination, implying a small contribution from particles elastically scattered at forward angles, as theoretically predicted for He but not for Kr.
Current trends show a rise of attention given to breast cancer patients' quality of life and the surgical reconstructive result. Along with this trend, surgical training quality and efficacy are ...gaining importance and innovative training methods such as online videos shared on social media portals, are becoming main updating tools. In hazardous times like COVID-19 pandemic nowadays, online communication becomes of vital importance and adaptation and innovation are fundamental to keep research and education alive. The authors aimed to investigate the role of video and multimedia sources on the daily activity and surgical training of a representative group of surgeons specifically dedicated to oncologic, oncoplastic and reconstructive breast surgeries.
A survey was produced and administered to 20 major Italian Breast Centers. Collected data were analyzed with Fisher's Exact Test.
From October 2019 to March 2020, a total of 320 surveys were collected. Among the responders, there were 188 trainees (intern medical doctors and residents) and 110 faculty, 72% of them belonged to a plastic surgery environment, while 28% to general surgery environment. Almost all respondents have ever watched videos concerning breast surgery.
The results of the study show how breast surgeons rely on videos and web platforms, mostly YouTube, when searching for training info about surgical procedures. Social media offer great opportunities for sharing knowledge and diffusion of new ideas but greater attention to their reliability is mandatory.
Synopsis A new electrostatic positron beam at UCL is described. The beam incorporates a re-moderator to achieve brightness enhancement, time of flight facility for beam energy determination and ...improved signal to background ratio and a position sensitive detector for 2-D imaging of the beam spot. The apparatus is being employed for measuring the total cross section of positron scattering from krypton and helium in the energy range of (10 - 200) eV. Results will be presented at the conference.
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