17 research outputs found
Loss-Optimal Classification Trees: A Generalized Framework and the Logistic Case
The Classification Tree (CT) is one of the most common models in
interpretable machine learning. Although such models are usually built with
greedy strategies, in recent years, thanks to remarkable advances in
Mixer-Integer Programming (MIP) solvers, several exact formulations of the
learning problem have been developed. In this paper, we argue that some of the
most relevant ones among these training models can be encapsulated within a
general framework, whose instances are shaped by the specification of loss
functions and regularizers. Next, we introduce a novel realization of this
framework: specifically, we consider the logistic loss, handled in the MIP
setting by a linear piece-wise approximation, and couple it with
-regularization terms. The resulting Optimal Logistic Tree model
numerically proves to be able to induce trees with enhanced interpretability
features and competitive generalization capabilities, compared to the
state-of-the-art MIP-based approaches
MORFEO enters final design phase
MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations, formerly
MAORY), the MCAO system for the ELT, will provide diffraction-limited optical
quality to the large field camera MICADO. MORFEO has officially passed the
Preliminary Design Review and it is entering the final design phase. We present
the current status of the project, with a focus on the adaptive optics system
aspects and expected milestones during the next project phase
Soft and Hard Iron Compensation for the Compasses of an Operational Towed Hydrophone Array without Sensor Motion by a Helmholtz Coil
Usually, towed hydrophone arrays are instrumented with a set of compasses. Data from these sensors are utilized while beamforming the acoustic signal for target bearing estimation. However, elements of the hydrophone array mounted in the neighborhood of a compass can affect the Earth’s magnetic field detection. The effects depend upon the materials and magnetic environment present in the vicinity of the platform hosting the compass. If the disturbances are constant in time, they can be compensated for by means of a magnetic calibration procedure. This process is commonly known as soft and hard iron compensation. In this paper, a solution is presented for carrying out the magnetic calibration of a COTS (Commercial Off the Shelf) digital compass without sensor motion. This approach is particularly suited in applications where a physical rotation of the platform that hosts the sensor is unfeasible. In our case, the platform consists in an assembled and operational towed hydrophone array. A standard calibration process relies on physical rotation of the platform and thus on the use of the geomagnetic field as a reference during the compensation. As a variation on this approach, we generate an artificial reference magnetic field to simulate the impractical physical rotation. We obtain this by using a tri-axial Helmholtz coil, which enables programmability of the reference magnetic field and assures the required field uniformity. In our work, the simulated geomagnetic field is characterized in terms of its uncertainty. The analysis indicates that our method and experimental set-up represent a suitably accurate approach for the soft and hard iron compensation of the compasses equipped in the hydrophone array under test
The PlasticPelagos Project: microplastics, convergence areas and fin whales in the Pelagos Sanctuary (northwestern Mediterranean Sea)
The Mediterranean Sea is one of the areas most affected by litter in the world. The highest
percentage (~80%) of marine litter consists of plastic including microplastics (plastic fragments
smaller than 5 mm). Research on the impact of microplastics on large filter-feeding species, such as
fin whale (Balaenoptera physalus), is still in its infancy. Here we present the results of the
PlasticPelagos pilot project focused to investigate the overlap between microplastics and fin whale
feeding ground in convergence areas (gyres) of the SPAMI Pelagos Sanctuary (northwestern
Mediterranean Sea). A sampling cruise carried out in September 2014 along 967 miles allowed
collecting surface microplastics samples (n=21), counting macrolitter, monitoring cetaceans and
collecting skin biopsies of fin whales. Two operational models of ocean circulation (LaMMA) and
fin whale potential habitat (JRC) were used to localize possible convergence areas of marine litter
and probable presence of foraging fin whales respectively. A multi-layer approach was used to
investigate the possible overlap between microplastics convergence areas and fin whale feeding
ground. The three layers of field data, microplastics abundance (items-micro/m2), macroplastics
abundance (items-macro/km2) and cetacean presence were compared with the maps of ocean
circulation and fin whale potential feeding habitat. The plastic data set has revealed high occurrence
of microplastics (from 0.009 to 0.260 items/m2) in the investigated surface neustonic/planktonic
samples and a significant overlap with the areas showing high macroplastic density (0.6127, R.
Spearman). Moreover the areas of high densities of microplastics detected on circulation maps
largely overlapped with fin whale potential feeding grounds suggesting that whales are particularly
exposed to microplastics threat when foraging in the Pelagos Sanctuary during summer. The
ecotoxicological analysis of the collected fin whale skin biopsies will be carried out to elaborate
further on this hypothesis
Plastic debris occurrence, convergence areas and fin whales feeding ground in the Mediterranean Marine Protected Area Pelagos Sanctuary: a modelling approach
The Mediterranean Sea is greatly affected by marine litter. In this area, research
on the impact of plastic debris (including microplastics) on biota, particularly large
filter-feeding species such as the fin whale (Balaenoptera physalus), is still in its
infancy. We investigated the possible overlap between microplastic, mesoplastic and
macrolitter accumulation areas and the fin whale feeding grounds in in a pelagic Specially
Protected Area of Mediterranean Importance (SPAMI): the Pelagos Sanctuary. Models
of ocean circulation and fin whale potential habitat were merged to compare marine
litter accumulation with the presence of whales. Additionally, field data on microplastics,
mesoplastics, and macrolitter abundance and cetacean presence were simultaneously
collected. The resulting data were compared, as a multi-layer, with the simulated
distribution of plastic concentration and the whale habitat model. These data showed
a high occurrence of microplastics (mean: 0.082 items/m2, STD ± 0.079 items/m2)
spatial distribution agreed with our modeling results. Areas with high microplastic
density significantly overlapped with areas of high macroplastic density. The most
abundant polymer detected in all the sampling sites was polyethylene (PE), suggesting
fragmentation of larger packaging items as the primary source. To our knowledge, this is
the first study in the Pelagos Sanctuary in which the simulated microplastic distribution
has been confirmed by field observations. The overlap between the fin whale feeding
habitat and the microplastic hot spots is an important contribution for risk assessment
of fin whale exposure to microplastics.JRC.D.2-Water and Marine Resource
No evidence of disease activity (NEDA-3) and disability improvement after alemtuzumab treatment for multiple sclerosis: a 36-month real-world study
In this retrospective, multicenter, real-world study we collected clinical and magnetic resonance imaging (MRI) data of all patients (n = 40) with relapsing-remitting multiple sclerosis (RRMS) treated with alemtuzumab according to a "free-of-charge" protocol available before the drug marketing approval in Italy. Almost all (39/40) started alemtuzumab after discontinuing multiple disease-modifying treatments (DMTs) because of either lack of response or safety concerns. We considered the proportion of alemtuzumab-treated patients who had no evidence of disease activity (NEDA-3) and disability improvement over a 36-month follow-up period. NEDA-3 was defined as absence of relapses, disability worsening, and MRI activity. Disability improvement was defined as a sustained reduction of ≥ 1-point in Expanded Disability Status Scale (EDSS) score. At follow-up, 18 (45%) patients achieved NEDA-3, 30 (75%) were relapse-free, 33 (82.5%) were EDSS worsening-free, and 25 (62.5%) were MRI activity-free. Eleven (27.5%) patients had a sustained disability improvement. We found no predictor for the NEDA-3 status, while the interaction of higher EDSS score by higher number of pre-alemtuzumab relapses was associated with a greater chance of disability improvement (odds ratio 1.10, p = 0.049). Our study provides real-world evidence that alemtuzumab can promote clinical and MRI disease remission, as well as disability improvement, in a significant proportion of patients with RRMS despite prior multiple DMT failures. The drug safety profile was consistent with data available from clinical trials