459 research outputs found
A nonmonotone GRASP
A greedy randomized adaptive search procedure (GRASP) is an itera-
tive multistart metaheuristic for difficult combinatorial optimization problems. Each
GRASP iteration consists of two phases: a construction phase, in which a feasible
solution is produced, and a local search phase, in which a local optimum in the
neighborhood of the constructed solution is sought. Repeated applications of the con-
struction procedure yields different starting solutions for the local search and the
best overall solution is kept as the result. The GRASP local search applies iterative
improvement until a locally optimal solution is found. During this phase, starting from
the current solution an improving neighbor solution is accepted and considered as the
new current solution. In this paper, we propose a variant of the GRASP framework that
uses a new ânonmonotoneâ strategy to explore the neighborhood of the current solu-
tion. We formally state the convergence of the nonmonotone local search to a locally
optimal solution and illustrate the effectiveness of the resulting Nonmonotone GRASP
on three classical hard combinatorial optimization problems: the maximum cut prob-
lem (MAX-CUT), the weighted maximum satisfiability problem (MAX-SAT), and
the quadratic assignment problem (QAP)
Highâtech training for birds of prey
Raptors are some of the most atârisk groups of birds in the world and saving these top predators is essential for maintaining the health of many ecosystems. After hospitalization, raptors are often released when muscular recovery is still unfitting when they are unable to hunt efficiently and are at risk of dying from starvation within a few days. On the other hand, if a convalescent bird is trained with the only use of classic falconry techniques, it is likely to remain dependent on the caretaker/falconer even long after the release, so unable to hunt independently. To overcome these problems, a new training method was conceived, which could improve raptorsâ muscular strength while limiting habituation to humans. This has been possible due to the combination of classic falconry techniques and modern technologies, such as the introduction of specific workouts with drones. Three falconry raptors and one wild Eurasian hobby were trained through highâtech falconry to develop the ability to catch, grasp, and airlift their prey at a different speed, altitude, and resistance. The main findings of this study were: (i) The rapid increase of the raptorsâ speed; (ii) the muscular growth and endurance, and (iii) successful reintroduction of a wild bird
Effects of personal and situational factors on self-referenced doping likelihood
Objectives
The present study examined the role of moral identity, self-regulatory efficacy and moral disengagement on athletes' doping likelihood in situations representing potential benefits and costs for themselves.
Design
Using a cross-sectional design, doping likelihood was assessed indirectly via hypothetical scenarios.
Method
Athletes (NâŻ=âŻ262) indicated their likelihood of doping in hypothetical situations and completed measures of moral identity, doping self-regulatory efficacy, and doping moral disengagement.
Results
Doping was more likely in benefit situations than in cost situations. Doping likelihood was negatively correlated moral identity, negatively correlated with self-regulatory efficacy, and positively correlated with moral disengagement in both situations. The coefficients were higher for moral identity in cost situations, self-regulatory efficacy in benefit situations, and moral disengagement in benefit situations. Process analyses indicated that moral identity was directly related to doping likelihood only in cost situations and indirectly related to doping likelihood via increased self-regulatory efficacy only in benefit situations. Moral identity was indirectly related to doping likelihood via decreased moral disengagement and via increased self-regulatory efficacy and decreased moral disengagement in both situations.
Conclusions
By showing that doping likelihood is associated with personal and situational factors our findings provide support for a social cognitive model of doping based on Banduraâs theory of moral thought and action and Aquinoâs theory of moral identity
Behavioral Restriction Determines Left Attentional Bias: Preliminary Evidences From COVID-19 Lockdown
During the COVID-19 lockdown, individuals were forced to remain at home, hence severely limiting the interaction within environmental stimuli, reducing the cognitive load placed on spatial competences. The effects of the behavioral restriction on cognition have been little examined. The present study is aimed at analyzing the effects of lockdown on executive function prominently involved in adapting behavior to new environmental demands. We analyze non-verbal fluency abilities, as indirectly providing a measure of cognitive flexibility to react to spatial changes. Sixteen students (mean age 20.75; SD 1.34), evaluated before the start of the lockdown (T1) in a battery of psychological tasks exploring different cognitive domains, have been reassessed during lockdown (T2). The assessment included the modified Five-Point Test (m-FPT) to analyze non-verbal fluency abilities. At T2, the students were also administered the Toronto Alexithymia Scale (TAS-20). The restriction of behaviors following a lockdown determines increased non-verbal fluency, evidenced by the significant increase of the number of new drawings. We found worsened verbal span, while phonemic verbal fluency remained unchanged. Interestingly, we observed a significant tendency to use the left part of each box in the m-FPT correlated with TAS-20 and with the subscales that assess difficulty in describing and identifying feelings. Although our data were collected from a small sample, they evidence that the restriction of behaviors determines a leftward bias, suggesting a greater activation of the right hemisphere, intrinsically connected with the processing of non-verbal information and with the need to manage an emotional situation
Fishing activities overlap with bottlenose dolphin core habitats of Ischia and Procida islands
Tursiops truncatus â the common bottlenose dolphin â is a species of conservation
interest, listed in Annex II and IV of Habitat Directive (92/43/CEE) that requires
strict protection and the creation of specially protected areas for conservation,
managed according to the ecological requirements of the species, within the
âNature 2000â network. A local population of bottlenose dolphins has been
monitored over fifteen years in the sea waters around Ischia and Procida Islands
in the frame of the Ischia Dolphin Project, an ongoing long-term research program
on Tyrrhenian cetaceans. The study area lies partially within the boundaries of
"Regno di Nettuno" Marine Protected Area (MPA), which is classified by IUCN as
an Important Marine Mammal Area (IMMA), where pods of cetacean key species
such as common dolphin (Delphinus Delphis), bottlenose dolphin, and fin whale
(Balaenoptera physalus) live. Investigating habitat exploitation by bottlenose
dolphins is crucial for conserving this protected species. Between 2004 and 2018,
1186 surveys were performed, resulting in 91 encounters with the species. To
investigate bottlenose dolphins' habitat exploitation, we combined both
behavioral observations and spatial analysis. Kernel Density Estimation and
Hotspot analysis allowed to delineate fine-scale areas of higher concentration of
critical activities (feeding, socializing/mating, resting) and interactions with
fisheries (gillnets and trawlers). Results show a vital region for feeding, resting,
social cohesion, and mating, i.e. essential habitat for bottlenose dolphins.
Unfortunately, these critical habitats are only partially protected by the zonation
of the MPA, because it overlaps with human activities, especially fishing. Although
the influence of fisheries on dolphins' behavior and movements needs further
investigation, the results thus far collected suggest that effective management
measures should take into account the human-animal conflict that can arise in
these critical areas
Machine Learning-Based Classification to Disentangle EEG Responses to TMS and Auditory Input
The combination of transcranial magnetic stimulation (TMS) and electroencephalography (EEG) offers an unparalleled opportunity to study cortical physiology by characterizing brain electrical responses to external perturbation, called transcranial-evoked potentials (TEPs). Although these reflect cortical post-synaptic potentials, they can be contaminated by auditory evoked potentials (AEPs) due to the TMS click, which partly show a similar spatial and temporal scalp distribution. Therefore, TEPs and AEPs can be difficult to disentangle by common statistical methods, especially in conditions of suboptimal AEP suppression. In this work, we explored the ability of machine learning
algorithms to distinguish TEPs recorded with masking of the TMS click, AEPs and non-masked TEPs in a sample of healthy subjects. Overall, our classifier provided reliable results at the single subject level, even for signals where differences were not shown in previous works. Classification accuracy (CA) was lower at the group level, when different subjects were used for training and test phases, and when three stimulation conditions instead of two were compared. Lastly, CA was higher when average, rather than single-trial TEPs, were used. In conclusion, this proof-of-concept study proposes machine learning as a promising tool to separate pure TEPs from those contaminated by sensory input
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