المؤلفون: Frati, Lapo, Traft, Neil, Clune, Jeff, Cheney, Nick

مصطلحات موضوعية: Computer Science - Machine Learning, Computer Science - Computer Vision and Pattern Recognition, Computer Science - Neural and Evolutionary Computing

الوصف: This work identifies a simple pre-training mechanism that leads to representations exhibiting better continual and transfer learning. This mechanism -- the repeated resetting of weights in the last layer, which we nickname "zapping" -- was originally designed for a meta-continual-learning procedure, yet we show it is surprisingly applicable in many settings beyond both meta-learning and continual learning. In our experiments, we wish to transfer a pre-trained image classifier to a new set of classes, in a few shots. We show that our zapping procedure results in improved transfer accuracy and/or more rapid adaptation in both standard fine-tuning and continual learning settings, while being simple to implement and computationally efficient. In many cases, we achieve performance on par with state of the art meta-learning without needing the expensive higher-order gradients, by using a combination of zapping and sequential learning. An intuitive explanation for the effectiveness of this zapping procedure is that representations trained with repeated zapping learn features that are capable of rapidly adapting to newly initialized classifiers. Such an approach may be considered a computationally cheaper type of, or alternative to, meta-learning rapidly adaptable features with higher-order gradients. This adds to recent work on the usefulness of resetting neural network parameters during training, and invites further investigation of this mechanism.

الوصول الحر: http://arxiv.org/abs/2310.07996Test

المؤلفون: Da Lozzo, Giordano, Di Battista, Giuseppe, Frati, Fabrizio, Grosso, Fabrizio, Patrignani, Maurizio

مصطلحات موضوعية: Computer Science - Data Structures and Algorithms, Computer Science - Computational Geometry, Mathematics - Combinatorics

الوصف: We propose efficient algorithms for enumerating the notorious combinatorial structures of maximal planar graphs, called canonical orderings and Schnyder woods, and the related classical graph drawings by de Fraysseix, Pach, and Pollack [Combinatorica, 1990] and by Schnyder [SODA, 1990], called canonical drawings and Schnyder drawings, respectively. To this aim (i) we devise an algorithm for enumerating special $e$-bipolar orientations of maximal planar graphs, called canonical orientations; (ii) we establish bijections between canonical orientations and canonical drawings, and between canonical orientations and Schnyder drawings; and (iii) we exploit the known correspondence between canonical orientations and canonical orderings, and the known bijection between canonical orientations and Schnyder woods. All our enumeration algorithms have $O(n)$ setup time, space usage, and delay between any two consecutively listed outputs, for an $n$-vertex maximal planar graph.

الوصول الحر: http://arxiv.org/abs/2310.02247Test

المؤلفون: Frati, Fabrizio

مصطلحات موضوعية: Computer Science - Data Structures and Algorithms, Computer Science - Discrete Mathematics

الوصف: We show an $O(n)$-time reduction from the problem of testing whether a multiset of positive integers can be partitioned into two multisets so that the sum of the integers in each multiset is equal to $n/2$ to the problem of testing whether an $n$-vertex biconnected outerplanar DAG admits an upward planar drawing. This constitutes the first barrier to the existence of efficient algorithms for testing the upward planarity of DAGs with no large triconnected minor. We also show a result in the opposite direction. Suppose that partitioning a multiset of positive integers into two multisets so that the sum of the integers in each multiset is $n/2$ can be solved in $f(n)$ time. Let $G$ be an $n$-vertex biconnected outerplanar DAG and $e$ be an edge incident to the outer face of an outerplanar drawing of $G$. Then it can be tested in $O(f(n))$ time whether $G$ admits an upward planar drawing with $e$ on the outer face.

الوصول الحر: http://arxiv.org/abs/2307.13799Test

المؤلفون: Petak, Csenge, Frati, Lapo, Pespeni, Melissa H., Cheney, Nick

مصطلحات موضوعية: Quantitative Biology - Populations and Evolution

الوصف: In environments that vary frequently and unpredictably, bet-hedgers can overtake the population. Diversifying bet-hedgers have a diverse set of offspring so that, no matter the conditions they find themselves in, at least some offspring will have high fitness. In contrast, conservative bet-hedgers have a set of offspring that all have an in-between phenotype compared to the specialists. Here, we use an evolutionary algorithm of gene regulatory networks to de novo evolve the two strategies and investigate their relative success in different parameter settings. We found that diversifying bet-hedgers almost always evolved first, but then eventually got outcompeted by conservative bet-hedgers. We argue that even though similar selection pressures apply to the two bet-hedger strategies, conservative bet-hedgers could win due to the robustness of their evolved networks, in contrast to the sensitive networks of the diversifying bet-hedgers. These results reveal an unexplored aspect of the evolution of bet-hedging that could shed more light on the principles of biological adaptation in variable environmental conditions.
Comment: Accepted at the Genetic and Evolutionary Computation Conference 2023 as a poster paper

الوصول الحر: http://arxiv.org/abs/2307.01602Test

المؤلفون: Francesco Frati, Alessandra D’Orazio, Valeria Gambacorta, Giacomo Ciacca, Giampietro Ricci, Mario Faralli

المصدر: Audiology Research, Vol 14, Iss 3, Pp 442-456 (2024)

مصطلحات موضوعية: hyperventilation, acute unilateral vestibulopathy, AUVP, vestibular neuritis, hyperventilation-induced nystagmus, HVIN, Otorhinolaryngology, RF1-547

الوصف: Hyperventilation induces metabolic changes that can elicit nystagmus (hyperventilation-induced nystagmus, HVIN) in various vestibular disorders, revealing vestibular imbalance and bringing out central or peripheral asymmetries. In acute unilateral vestibulopathy (AUVP, namely vestibular neuritis), hyperventilation can induce different patterns of nystagmus (excitatory, inhibitory, or negative), disclosing or modifying existing static vestibular asymmetries through its ability to invalidate compensation or increase peripheral excitability. In this context, we followed the evolutionary stages of HVIN in AUVP across 35 consecutive patients, with the goal of assessing alterations in the oculomotor pattern caused by hyperventilation over time. In the acute phase, the incidence of the excitatory pattern (and the strongly excitatory one, consisting of a reversal nystagmus evoked by hyperventilation) was significantly higher compared to the inhibitory pattern; then, a progressive reduction in the incidence of the excitatory pattern and a concomitant gradual increase in the incidence of the inhibitory one were observed in the follow-up period. Assuming the role of the ephaptic effect and the transient loss of vestibular compensation as opposing mechanisms, i.e., excitatory and inhibitory, respectively, the oculomotor pattern evoked by hyperventilation is the result of the interaction of these two factors. The data obtained allowed us to hypothesize an interpretative model regarding the pathogenetic aspects of responses evoked by hyperventilation and the etiologies of the disease: according to our hypotheses, the excitatory pattern implies a neuritic (viral) form of AUVP; instead, the inhibitory (and negative) one can be an expression of both the neuritic (viral) and vascular forms of the disease.

وصف الملف: electronic resource

العلاقة: https://www.mdpi.com/2039-4349/14/3/37Test; https://doaj.org/toc/2039-4349Test

الوصول الحر: https://doaj.org/article/e765398fa9bc4886b730b62603a2bd64Test

المؤلفون: Natasha Wills-Ibarra, Keryn Chemtob, Heather Hart, Francesca Frati, Keeley J Pratt, Geoff DC Ball, Andraea Van Hulst

المصدر: BMC Pediatrics, Vol 24, Iss 1, Pp 1-21 (2024)

مصطلحات موضوعية: Children and adolescents, Childhood obesity, Family systems, Lifestyle behaviours, Obesity management, Pediatrics, RJ1-570

الوصف: Abstract Family-based obesity management interventions targeting child, adolescent and parental lifestyle behaviour modifications have shown promising results. Further intervening on the family system may lead to greater improvements in obesity management outcomes due to the broader focus on family patterns and dynamics that shape behaviours and health. This review aimed to summarize the scope of pediatric obesity management interventions informed by family systems theory (FST). Medline, Embase, CINAHL and PsycInfo were searched for articles where FST was used to inform pediatric obesity management interventions published from January 1980 to October 2023. After removal of duplicates, 6053 records were screened to determine eligibility. Data were extracted from 50 articles which met inclusion criteria; these described 27 unique FST-informed interventions. Most interventions targeted adolescents (44%), were delivered in outpatient hospital settings (37%), and were delivered in person (81%) using group session modalities (44%). Professionals most often involved were dieticians and nutritionists (48%). We identified 11 FST-related concepts that guided intervention components, including parenting skills, family communication, and social/family support. Among included studies, 33 reported intervention effects on at least one outcome, including body mass index (BMI) (n = 24), lifestyle behaviours (physical activity, diet, and sedentary behaviours) (n = 18), mental health (n = 12), FST-related outcomes (n = 10), and other outcomes (e.g., adiposity, cardiometabolic health) (n = 18). BMI generally improved following interventions, however studies relied on a variety of comparison groups to evaluate intervention effects. This scoping review synthesises the characteristics and breadth of existing FST-informed pediatric obesity management interventions and provides considerations for future practice and research.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1471-2431Test

الوصول الحر: https://doaj.org/article/7519a26a8d244f8f849503504a5e48a0Test

المؤلفون: Francesco Nardi, Sara Boschi, Rebecca Funari, Claudio Cucini, Elena Cardaioli, Daniel Potter, Shin-Ichiro Asano, Duarte Toubarro, Michela Meier, Francesco Paoli, Antonio Carapelli, Francesco Frati

المصدر: Scientific Reports, Vol 14, Iss 1, Pp 1-13 (2024)

مصطلحات موضوعية: Medicine, Science

الوصف: Abstract The Japanese beetle Popillia japonica is a pest insect that feeds on hundreds of species of wild and cultivated plants including important fruit, vegetable, and field crops. Native to Japan, the pest has invaded large areas of the USA, Canada, the Azores (Portugal), Italy, and Ticino (Switzerland), and it is considered a priority for control in the European Union. We determined the complete mitochondrial genome sequence in 86 individuals covering the entire distribution of the species. Phylogenetic analysis supports a major division between South Japan and Central/North Japan, with invasive samples coming from the latter. The origin of invasive USA samples is incompatible, in terms of the timing of the event, with a single introduction, with multiple Japanese lineages having been introduced and one accounting for most of the population expansion locally. The origin of the two invasive European populations is compatible with two different invasions followed by minimal differentiation locally. Population analyses provide the possibility to estimate the rate of sequence change from the data and to date major invasion events. Demographic analysis identifies a population expansion followed by a period of contraction prior to the invasion. The present study adds a time and demographic dimension to available reconstructions.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/2045-2322Test

الوصول الحر: https://doaj.org/article/9444c1be6630498eb18c11875a1bf755Test

المؤلفون: Claudio Cucini, Sara Boschi, Rebecca Funari, Elena Cardaioli, Nicola Iannotti, Giovanni Marturano, Francesco Paoli, Mirella Bruttini, Antonio Carapelli, Francesco Frati, Francesco Nardi

المصدر: BMC Genomics, Vol 25, Iss 1, Pp 1-17 (2024)

مصطلحات موضوعية: Beetles, Invasive species, Japanese beetle, Odorant receptors, Ionotropic receptors, Gustatory receptors, Biotechnology, TP248.13-248.65, Genetics, QH426-470

الوصف: Abstract Background The spread of Popillia japonica in non-native areas (USA, Canada, the Azores islands, Italy and Switzerland) poses a significant threat to agriculture and horticulture, as well as to endemic floral biodiversity, entailing that appropriate control measures must be taken to reduce its density and limit its further spread. In this context, the availability of a high quality genomic sequence for the species is liable to foster basic research on the ecology and evolution of the species, as well as on possible biotechnologically-oriented and genetically-informed control measures. Results The genomic sequence presented and described here is an improvement with respect to the available draft sequence in terms of completeness and contiguity, and includes structural and functional annotations. A comparative analysis of gene families of interest, related to the species ecology and potential for polyphagy and adaptability, revealed a contraction of gustatory receptor genes and a paralogous expansion of some subgroups/subfamilies of odorant receptors, ionotropic receptors and cytochrome P450s. Conclusions The new genomic sequence as well as the comparative analyses data may provide a clue to explain the staggering invasive potential of the species and may serve to identify targets for potential biotechnological applications aimed at its control.

وصف الملف: electronic resource

العلاقة: https://doaj.org/toc/1471-2164Test

الوصول الحر: https://doaj.org/article/8e98c7c3fd3244f9ac4a26be4981632fTest

المؤلفون: Buchin, Kevin, Evans, Will, Frati, Fabrizio, Kostitsyna, Irina, Löffler, Maarten, Ophelders, Tim, Wolff, Alexander

مصطلحات موضوعية: Computer Science - Computational Geometry, Computer Science - Data Structures and Algorithms

الوصف: In this paper, we investigate crossing-free 3D morphs between planar straight-line drawings. We show that, for any two (not necessarily topologically equivalent) planar straight-line drawings of an $n$-vertex planar graph, there exists a piecewise-linear crossing-free 3D morph with $O(n^2)$ steps that transforms one drawing into the other. We also give some evidence why it is difficult to obtain a linear lower bound (which exists in 2D) for the number of steps of a crossing-free 3D morph.

الوصول الحر: http://arxiv.org/abs/2210.05384Test

المؤلفون: Alegria, Carlos, Da Lozzo, Giordano, Di Battista, Giuseppe, Frati, Fabrizio, Grosso, Fabrizio, Patrignani, Maurizio

مصطلحات موضوعية: Computer Science - Computational Geometry, Computer Science - Data Structures and Algorithms

الوصف: A rectangular drawing of a planar graph $G$ is a planar drawing of $G$ in which vertices are mapped to grid points, edges are mapped to horizontal and vertical straight-line segments, and faces are drawn as rectangles. Sometimes this latter constraint is relaxed for the outer face. In this paper, we study rectangular drawings in which the edges have unit length. We show a complexity dichotomy for the problem of deciding the existence of a unit-length rectangular drawing, depending on whether the outer face must also be drawn as a rectangle or not. Specifically, we prove that the problem is NP-complete for biconnected graphs when the drawing of the outer face is not required to be a rectangle, even if the sought drawing must respect a given planar embedding, whereas it is polynomial-time solvable, both in the fixed and the variable embedding settings, if the outer face is required to be drawn as a rectangle.
Comment: Appears in the Proceedings of the 30th International Symposium on Graph Drawing and Network Visualization (GD 2022)

الوصول الحر: http://arxiv.org/abs/2208.14142Test