144 research outputs found
Enhancing glomeruli segmentation through cross-species pre-training
The importance of kidney biopsy, a medical procedure in which a small tissue sample is extracted from the kidney for examination, is increasing due to the rising incidence of kidney disorders. This procedure helps diagnosing several kidney diseases which are cause of kidney function changes, as well as guiding treatment decisions, and evaluating the suitability of potential donor kidneys for transplantation. In this work, a deep learning system for the automatic segmentation of glomeruli in biopsy kidney images is presented. A novel cross-species transfer learning approach, in which a semantic segmentation network is trained on mouse kidney tissue images and then fine-tuned on human data, is proposed to boost the segmentation performance. The experiments conducted using two deep semantic segmentation networks, MobileNet and SegNeXt, demonstrated the effectiveness of the cross-species pre-training approach leading to an increased generalization ability of both models
analysis of brain nmr images for age estimation with deep learning
Abstract During the last decade, deep learning and Convolutional Neural Networks (CNNs) have produced a devastating impact on computer vision, yielding exceptional results on a variety of problems, including analysis of medical images. Recently, these techniques have been extended to 3D images with the downside of a large increase in the computational load. In particular, state-of-the-art CNNs have been used for brain Nuclear Magnetic Resonance (NMR) imaging, with the aim of estimating the patients' age. In fact, a large discrepancy between the real and the estimated age is a clear alarm for the onset of neurodegenerative diseases, such as some types of early dementia and Alzheimer's disease. In this paper, we propose an effective alternative to 3D convolutions that guarantees a significant reduction of the computational requirements for this kind of analysis. The proposed architectures achieve comparable results with the competitor 3D methods, requiring only a fraction of the training time and GPU memory
Detection of the high energy component of Jovian electrons in Low Earth Orbit with the PAMELA experiment
The PAMELA experiment is devoted to the study of cosmic rays in Low Earth
Orbit with an apparatus optimized to perform a precise determination of the
galactic antimatter component of c.r. It is constituted by a number of
detectors built around a permanent magnet spectrometer. PAMELA was launched in
space on June 15th 2006 on board the Russian Resurs-DK1 satellite for a mission
duration of three years. The characteristics of the detectors, the long
lifetime and the orbit of the satellite, will allow to address several aspects
of cosmic-ray physics. In this work we discuss the observational capabilities
of PAMELA to detect the electron component above 50 MeV. The magnetic
spectrometer allows a detailed measurement of the energy spectrum of electrons
of galactic and Jovian origin. Long term measurements and correlations with
Earth-Jupiter 13 months synodic period will allow to separate these two
contributions and to measure the primary electron Jovian component, dominant in
the 50-70 MeV energy range. With this technique it will also be possible to
study the contribution to the electron spectrum of Jovian e- reaccelerated up
to 2 GeV at the Solar Wind Termination Shock.Comment: On behalf of PAMELA collaboration. Accepted for publication on
Advances in Space Researc
CALOCUBE: An approach to high-granularity and homogenous calorimetry for space based detectors
Future space experiments dedicated to the observation of high-energy gamma and cosmic rays will increasingly rely on a highly performing calorimetry apparatus, and their physics performance will be primarily determined by the geometrical dimensions and the energy resolution of the calorimeter deployed. Thus it is extremely important to optimize its geometrical acceptance, the granularity, and its absorption depth for the measurement of the particle energy with respect to the total mass of the apparatus which is the most important constraint for a space launch. The proposed design tries to satisfy these criteria while staying within a total mass budget of about 1.6 tons. Calocube is a homogeneous calorimeter instrumented with Cesium iodide (CsI) crystals, whose geometry is cubic and isotropic, so as to detect particles arriving from every direction in space, thus maximizing the acceptance; granularity is obtained by filling the cubic volume with small cubic CsI crystals. The total radiation length in any direction is more than adequate for optimal electromagnetic particle identification and energy measurement, whilst the interaction length is at least sufficient to allow a precise reconstruction of hadronic showers. Optimal values for the size of the crystals and spacing among them have been studied. The design forms the basis of a three-year R&D activity which has been approved and financed by INFN. An overall description of the system, as well as results from preliminary tests on particle beams will be described
Two years of flight of the Pamela experiment: results and perspectives
PAMELA is a satellite borne experiment designed to study with great accuracy
cosmic rays of galactic, solar, and trapped nature in a wide energy range
(protons: 80 MeV-700 GeV, electrons 50 MeV-400 GeV). Main objective is the
study of the antimatter component: antiprotons (80 MeV-190 GeV), positrons (50
MeV-270 GeV) and search for antinuclei with a precision of the order of
). The experiment, housed on board the Russian Resurs-DK1 satellite,
was launched on June, 2006 in a orbit with an
inclination of 70 degrees. In this work we describe the scientific objectives
and the performance of PAMELA in its first two years of operation. Data on
protons of trapped, secondary and galactic nature - as well as measurements of
the December 2006 Solar Particle Event - are also provided.Comment: To appear on J. Phys. Soc. Jpn. as part of the proceedings of the
International Workshop on Advances in Cosmic Ray Science March, 17-19, 2008
Waseda University, Shinjuku, Tokyo, Japa
Observations of the December 13 and 14, 2006, Solar Particle Events in the 80 MeV/n - 3 GeV/n range from space with PAMELA detector
We present the space spectrometer PAMELA observations of proton and helium
fluxes during the December 13 and 14, 2006 solar particle events. This is the
first direct measurement of the solar energetic particles in space with a
single instrument in the energy range from 80 MeV/n up to 3
GeV/n. In the event of December 13 measured energy spectra of solar protons and
helium were compared with results obtained by neutron monitors and other
detectors. Our measurements show a spectral behaviour different from those
derived from the neutron monitor network. No satisfactory analytical fitting
was found for the energy spectra. During the first hours of the December 13
event solar energetic particles spectra were close to the exponential form
demonstrating rather significant temporal evolution. Solar He with energy up to
~1 GeV/n was recorded on December 13. In the event of December 14 energy of
solar protons reached ~600 MeV whereas maximum energy of He was below 100
MeV/n. The spectra were slightly bended in the lower energy range and preserved
their form during the second event. Difference in the particle flux appearance
and temporal evolution in these two events may argue for a special conditions
leading to acceleration of solar particles up to relativistic energies.Comment: Accepted for publication on Astrophysical journa
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