Robust leave-one-out cross-validation for high-dimensional Bayesian models

Leave-one-out cross-validation (LOO-CV) is a popular method for estimating out-of-sample predictive accuracy. However, computing LOO-CV criteria can be computationally expensive due to the need to fit the model multiple times. In the Bayesian context, importance sampling provides a possible solution but classical approaches can easily produce estimators whose variance is infinite, making them potentially unreliable. Here we propose and analyze a novel mixture estimator to compute Bayesian LOO-CV criteria. Our method retains the simplicity and computational convenience of classical approaches, while guaranteeing finite variance of the resulting estimators. Both theoretical and numerical results are provided to illustrate the improved robustness and efficiency. The computational benefits are particularly significant in high-dimensional problems, allowing to perform Bayesian LOO-CV for a broader range of models. The proposed methodology is easily implementable in standard probabilistic programming software and has a computational cost roughly equivalent to fitting the original model once.Comment: 37 pages, 8 figure

Newton-Raphson Consensus for Distributed Convex Optimization

We address the problem of distributed uncon- strained convex optimization under separability assumptions, i.e., the framework where each agent of a network is endowed with a local private multidimensional convex cost, is subject to communication constraints, and wants to collaborate to compute the minimizer of the sum of the local costs. We propose a design methodology that combines average consensus algorithms and separation of time-scales ideas. This strategy is proved, under suitable hypotheses, to be globally convergent to the true minimizer. Intuitively, the procedure lets the agents distributedly compute and sequentially update an approximated Newton- Raphson direction by means of suitable average consensus ratios. We show with numerical simulations that the speed of convergence of this strategy is comparable with alternative optimization strategies such as the Alternating Direction Method of Multipliers. Finally, we propose some alternative strategies which trade-off communication and computational requirements with convergence speed.Comment: 18 pages, preprint with proof

LoRa Multi-Hop Networks for Monitoring Underground Mining Environments

Internet of Things applications have gained widespread recognition for their efficacy in typical scenarios, such as smart cities and smart healthcare. Nonetheless, there exist numerous unconventional situations where IoT technologies have not yet been massively applied, though they can be extremely useful. One of such domains is the underground mining sector, where enhancing automation monitoring through wireless communications is of essential significance. In this paper, we focus on the development, implementation, and evaluation of a LoRa-based multi-hop network tailored specifically for monitoring underground mining environments, where data traffic is sporadic, but energy efficiency is of paramount importance. We hence define a synchronization framework that makes it possible for the nodes to sleep for most of the time, waking up only when they need to exchange traffic. Notably, our network achieves a sub 40us proven synchronization accuracy between parent-child pairs with minimum overhead for diverse topologies, rendering it highly viable for subterranean operations. Furthermore, for proper network dimensioning, we model the interplay between network's throughput, frame size, and sampling periods of potential applications. Moreover, we propose a model to estimate devices' duty cycle based on their position within the multi-hop network, along with empirical observations for its validation. The proposed models make it possible to optimize the network's performance to meet the specific demands that can arise from the different subterranean use cases, in which robustness, low power operation, and compliance with radio-frequency regulations are key requirements that must be met

Limited-memory scaled gradient projection methods for real-time image deconvolution in microscopy

Gradient projection methods have given rise to effective tools for image deconvolution in several relevant areas, such as microscopy, medical imaging and astronomy. Due to the large scale of the optimization problems arising in nowadays imaging applications and to the growing request of real-time reconstructions, an interesting challenge to be faced consists in designing new acceleration techniques for the gradient schemes, able to preserve the simplicity and low computational cost of each iteration. In this work we propose an acceleration strategy for a state of the art scaled gradient projection method for image deconvolution in microscopy. The acceleration idea is derived by adapting a step-length selection rule, recently introduced for limited-memory steepest descent methods in unconstrained optimization, to the special constrained optimization framework arising in image reconstruction. We describe how important issues related to the generalization of the step-length rule to the imaging optimization problem have been faced and we evaluate the improvements due to the acceleration strategy by numerical experiments on large-scale image deconvolution problems

INTEGRATED STRATIGRAPHY FROM THE CONTRADA FORNAZZO SECTION, MONTE INICI, WESTERN SICILY, ITALY: PROPOSED G.S.S.P. FOR THE BASAL BOUNDARY OF THE TITHONIAN STAGE

This paper deals with a definition of the lower boundary stratotype of the Tithonian Stage in the Upper Jurassic succession of Monte Inici, Western Sicily. The upper member of the Rosso Ammonitico Fm. is 27 m thick and shows a typical nodular-calcareous lithofacies; its lower beds have been sampled for biostratigraphic and paleomagnetic purposes. Though the succession is affected by high stratigraphic condensation, the resulting hiatuses have been shown to be below biochronological resolution and thus do not hinder any biostratigraphic definition. The biostratigraphic analysis has been based on the rich ammonite assemblages in which the common genus Hybonoticeras is the index-key for characterizing the Kimmeridgian-Tithonian boundary. Four ammonite biozones have been identified; the basal Tithonian one is defined by the assemblage of Hybonoticeras gr. hybonotum and Haploceras staszycii. The recorded calcareous nannofossil bioevents allow recognition of the V. stradneri and C. mexicana Zones, whose boundary is located a little below the identified Tithonian lower boundary. The paleomagnetic record shows normal polarity in the S. darwini/V. albertinum Zone and mainly reverse polarity in the H. beckeri and H. hybonotum Zones, with three minor normal polarity intervals; the lower boundary of the Tithonian falls in the oldest of these intervals. The integrated multidisciplinary stratigraphic information gathered from the Contrada Fornazzo section defines the lower boundary of the H. hybonotum Zone at the base of Bed 110, and supplies elements of chrono-correlation sufficient to regard this section as a possible G.S.S.P. of the Tithonian Stage

Edukoi: developing an interactive sonification tool for astronomy between entertainment and education

Edukoi is a software that aims to make interactive sonification suitable to convey and extract information. The program design is a modification of the software Herakoi, which sonifies images in real time mapping pitch to colour using a motion-aware approach for allowing users to interact with images through sound. The pitch-colour association of Hearkoi, albeit pleasing from the entertainment side, is not efficient for communicating specific information regarding colours and hues to listeners. Hence we modified it to create an instrument to be used by visually impaired and sighted children to explore images through sound and extract accurate information. We aim at building a flexible software that can be used in middle-schools for both art and science teaching. We tested its effectiveness using astronomical images, given the great fascination that astronomy always has on kids of all ages and backgrounds. Astronomy is also considered a very visual science, a characteristic that prevents students from learning this subject and having a related career. With this project we aim to challenge this belief and give to students the possibility to explore astronomical data through sound. Here we discuss our experiment, the choices we made regarding sound mappings, and what psychophysiological aspects we aim to evaluate to validate and improve Edukoi.Comment: 4 pages, 3 figures, to be published in the proceedings of "The 28th International Conference on Auditory Display (ICAD 2023) - Special Session on Astronomical Data Sonification

Audio-Visual Dataset and Method for Anomaly Detection in Traffic Videos

We introduce the first audio-visual dataset for traffic anomaly detection taken from real-world scenes, called MAVAD, with a diverse range of weather and illumination conditions. In addition, we propose a novel method named AVACA that combines visual and audio features extracted from video sequences by means of cross-attention to detect anomalies. We demonstrate that the addition of audio improves the performance of AVACA by up to 5.2%. We also evaluate the impact of image anonymization, showing only a minor decrease in performance averaging at 1.7%

Cabotegravir Exposure of Zebrafish (Danio rerio) Embryos Impacts on Neurodevelopment and Behavior

As most new medications, Cabotegravir (CAB) was recently approved as an antiretroviral treatment of HIV infection without in-depth safety information on in utero exposure. Although no developmental toxicity in rats and rabbits was reported, recent studies demonstrated that CAB decreases pluripotency of human embryonic stem cells. CAB exposure effects during development were assessed in zebrafish embryos by the Fish Embryo Toxicity test after exposure at subtherapeutic concentrations up to 25x the human C-max. Larvae behavior was assessed by the light-dark locomotion test. The expression of factors involved in neurogenesis was evaluated by whole-mount in situ hybridization. CAB did not cause gross morphological defects at low doses, although pericardial edema, uninflated swim bladder, decreased heartbeats, growth delay, and decreased hatching rate were observed at the highest concentrations. Decreased locomotion was observed even at the subtherapeutic dose, suggesting alterations of nervous system integrity. This hypothesis was supported by the observation of decreased expression of crucial factors involved in early neuronal differentiation in diencephalic and telencephalic dopaminergic areas, midbrain/hindbrain boundary, and craniofacial ganglia. These findings support CAB effects on neurogenesis in zebrafish embryos and suggest long-term follow-up of exposed infants to provide data on drug safety during pregnancy

Artificial Diuresis: animal studies on efficacy and safety of a new miniaturized device for extracorporeal ultrafiltration

Introduction. We have recently developed a new miniaturized device for extracorporeal ultrafiltration to be used in patients with fluid overload: Artificial Diuresis-1, or AD1 (Medica S.p.A., Medolla, Italy). The device has a reduced priming volume and operates at very low pressure and flow regimes and is designed to perform extracorporeal UF at bedside. After accurate experiments carried out in vitro, we report in this paper the results of in vivo tests ultrafiltration session carried out in selected animals according to veterinary best practice. Materials and methods. The AD1 kit is pre-filled with sterile isotonic solution and operates with a polysulfone mini-filter MediSulfone (Polysulfone at 50000 Dalton). A collection bag with a volumetric scale is connected to the UF line and the ultrafiltrate is obtained by gravity based on the height at which the ultrafiltrate collection bag is placed. Animals were prepared and anesthetized. Jugular vein was cannulated with a double lumen catheter. Three six hours sessions of ultrafiltration were scheduled with a target fluid removal of 1500 ml. Heparin was used as anticoagulant.Results. In all treatments the target value of ultrafiltration was obtained in the absence of major clinical or technical problems with a maximum deviation from the scheduled ultrafiltration rate lower than 10%. The device resulted safe, reliable, accurate and easily usable thanks to a user friendly interface and the very small dimensions. Conclusions. This study opens the way for clinical trials in different settings including departments with low intensity of care and even in ambulatory centers or patient's home

Dolutegravir and Folic Acid Interaction during Neural System Development in Zebrafish Embryos

: Dolutegravir (DTG) is one of the most prescribed antiretroviral drugs for treating people with HIV infection, including women of child-bearing potential or pregnant. Nonetheless, neuropsychiatric symptoms are frequently reported. Early reports suggested that, probably in relation to folic acid (FA) shortage, DTG may induce neural tube defects in infants born to women taking the drug during pregnancy. Subsequent reports did not definitively confirm these findings. Recent studies in animal models have highlighted the association between DTG exposure in utero and congenital anomalies, and an increased risk of neurologic abnormalities in children exposed during in utero life has been reported. Underlying mechanisms for DTG-related neurologic symptoms and congenital anomalies are not fully understood. We aimed to deepen our knowledge on the neurodevelopmental effects of DTG exposure and further explore the protective role of FA by the use of zebrafish embryos. We treated embryos at 4 and up to 144 h post fertilization (hpf) with a subtherapeutic DTG concentration (1 μM) and observed the disruption of the anterior-posterior axis and several morphological malformations in the developing brain that were both prevented by pre-exposure (2 hpf) and rescued by post-exposure (10 hpf) with FA. By whole-mount in situ hybridization with riboprobes for genes that are crucial during the early phases of neurodevelopment (ntl, pax2a, ngn1, neurod1) and by in vivo visualization of the transgenic Tg(ngn1:EGFP) zebrafish line, we found that DTG induced severe neurodevelopmental defects over time in most regions of the nervous system (notochord, midbrain-hindbrain boundary, eye, forebrain, midbrain, hindbrain, spinal cord) that were mostly but not completely rescued by FA supplementation. Of note, we observed the disruption of ngn1 expression in the dopaminergic regions of the developing forebrain, spinal cord neurons and spinal motor neuron projections, with the depletion of the tyrosine hydroxylase (TH)+ dopaminergic neurons of the dorsal diencephalon and the strong reduction in larvae locomotion. Our study further supports previous evidence that DTG can interfere with FA pathways in the developing brain but also provides new insights regarding the mechanisms involved in the increased risk of DTG-associated fetal neurodevelopmental defects and adverse neurologic outcomes in in utero exposed children, suggesting the impairment of dopaminergic pathways