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 $\ell_1$-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