6,477 research outputs found
Improving Rigid 3-D Calibration for Robotic Surgery
Autonomy is the next frontier of research in robotic surgery and its aim is to improve the quality of surgical procedures in the next future. One fundamental requirement for autonomy is advanced perception capability through vision sensors. In this article, we propose a novel calibration technique for a surgical scenario with a da Vinci Research Kit (dVRK) robot. Camera and robotic arms calibration are necessary to precise position and emulate expert surgeon. The novel calibration technique is tailored for RGB-D cameras. Different tests performed on relevant use cases prove that we significantly improve precision and accuracy with respect to state of the art solutions for similar devices on a surgical-size setups. Moreover, our calibration method can be easily extended to standard surgical endoscope used in real surgical scenario
Global Analysis of Neutrino Data
In this talk I review the present status of neutrino masses and mixing and
some of their implications for particle physics phenomenology. I first discuss
the minimum extension of the Standard Model of particle physics required to
accommodate neutrino masses and introduce the new parameters present in the
model and in particular the possibility of leptonic mixing. I then describe the
phenomenology of neutrino masses and mixing leading to flavour oscillations and
present the existing evidence from solar, reactor, atmospheric and
long-baseline neutrinos as well as the results from laboratory searches at
short distances. I derive the allowed ranges for the mass and mixing parameters
when the bulk of data is consistently analyzed in the framework of mixing
between the three active neutrinos and obtain as a result the most up-to-date
determination of the leptonic mixing matrix. Then I briefly summarize the
status of some proposed phenomenological explanations to accommodate the LSND
results: the role of sterile neutrinos and the violation of CPT. Finally I
comment how within the present experimental precision it is possible to use the
observation of oscillation patterns to impose severe constraints on the
possible violation of fundamental symmetries in particle physics such as
Lorentz invariance or the weak equivalence principle.Comment: Talk given at the Nobel Symposium on Neutrino Physics, Haga Slott,
Enkoping, Swede
The X-Gamma Imaging Spectrometer (XGIS) onboard THESEUS
A compact and modular X and gamma-ray imaging spectrometer (XGIS) has been
designed as one of the instruments foreseen on-board the THESEUS mission
proposed in response to the ESA M5 call. The experiment envisages the use of
CsI scintillator bars read out at both ends by single-cell 25 mm 2 Silicon
Drift Detectors. Events absorbed in the Silicon layer (lower energy X rays) and
events absorbed in the scintillator crystal (higher energy X rays and
Gamma-rays) are discriminated using the on-board electronics. A coded mask
provides imaging capabilities at low energies, thus allowing a compact and
sensitive instrument in a wide energy band (~2 keV up to ~20 MeV). The
instrument design, expected performance and the characterization performed on a
series of laboratory prototypes are discussed.Comment: To be published in the Proceedings of the THESEUS Workshop 2017
(http://www.isdc.unige.ch/theseus/workshop2017.html), Journal of the Italian
Astronomical Society (Mem.SAIt), Editors L. Amati, E. Bozzo, M. Della Valle,
D. Gotz, P. O'Brien. Details on the THESEUS mission concept can be found in
the white paper Amati et al. 2017 (arXiv:171004638) and Stratta et al. 2017
(arXiv:1712.08153
New experimental limits on the alpha decays of lead isotopes
For the first time a PbWO4 crystal was grown using ancient Roman lead and it
was run as a cryogenic detector. Thanks to the simultaneous and independent
read-out of heat and scintillation light, the detector was able to discriminate
beta/gamma interactions with respect to alpha particles down to low energies.
New more stringent limits on the alpha decays of the lead isotopes are
presented. In particular a limit of T_{1/2} > 1.4*10^20 y at a 90% C.L. was
evaluated for the alpha decay of 204Pb to 200Hg
- …