524 research outputs found
Predictive brains: forethought and the levels of explanation
Is any unified theory of brain function possible? Following a line of thought dat- ing back to the early cybernetics (see, e.g., Cordeschi, 2002), Clark (in press) has proposed the action-oriented Hierarchical Predictive Coding (HPC) as the account to be pursued in the effort of gain- ing the “Grand Unified Theory of the Mind”—or “painting the big picture,” as Edelman (2012) put it. Such line of thought is indeed appealing, but to be effectively pursued it should be confronted with experimental findings and explana- tory capabilities (Edelman, 2012).
The point we are making in this note is that a brain with predictive capa- bilities is certainly necessary to endow the agent situated in the environment with forethought or foresight, a crucial issue to outline the unified account advocated by Clark. But the capacity for fore- thought is deeply entangled with the capacity for emotions and when emotions are brought into the game, cogni- tive functions become part of a large-scale functional brain network. However, for such complex networks a consistent view of hierarchical organization in large-scale functional networks has yet to emerge (Bressler and Menon, 2010), whilst heterarchical organization is likely to play a strategic role (Berntson et al., 2012). This raises the necessity of a multilevel approach that embraces causal relations across levels of explanation in either direc- tion (bottom–up or top–down), endorsing mutual calibration of constructs across levels (Berntson et al., 2012). Which, in turn, calls for a revised perspective on Marr’s levels of analysis framework (Marr, 1982). In the following we highlight some drawbacks of Clark’s proposal in address- ing the above issues
AI turns fifty: Revisiting its origins
The expression "artificial intelligence" (AI) was introduced by John McCarthy, and the official birth of AI is unanimously considered to be the 1956 Dartmouth Conference. Thus, AI turned fifty in 2006. How did AI begin? Several differently motivated analyses have been proposed as to its origins. In this paper a brief look at those that might be considered steps towards Dartmouth is attempted, with the aim of showing how a number of research topics and controversies that marked the short history of AI were touched on, or fairly well stated, during the year immediately preceding Dartmouth. The framework within which those steps were taken was the development of digital computers. Earlier computer applications in areas such as complex decision making and management, at that time dealt with by operations research techniques, were important in this story. The time was ripe for AI's intriguingly tumultuous development, marked as it has been by hopes and defeats, successes and difficulties
Rex
To summarise the work, which is my first serious attempt at painting, it was a process of trial and error. I chose the subject to be my golden retriever, Rex, because he had relatively straightforward features to paint, and he was also the only family member willing to sit still long enough for me to take a photo. I used the work mainly as a trial of my ability to blend colours and tones in a way that shows his features as accurately as possible, in particular his eyes, mouth and nose. Time and time again I would paint over these key areas only to painstakingly start again. While the experience was frustrating at times, I was very happy with the Result, and I think Rex was too
Sex-biased phenotypic plasticity affects sexual dimorphism patterns under changing environmental conditions
Sexual dimorphism is almost ubiquitous in animals. A common pattern observed across multiple taxa involves differences in development time (sexual bimaturism) and body size (sexual size dimorphism) between conspecific males and females. Furthermore, a strict association of dimorphism at these traits has been documented in several taxa, where the sex showing shorter development time also has a smaller body size than the other sex. Growth and development are strongly dependent on environmental conditions during individual life-cycle in ectotherms, inducing considerable phenotypic plasticity. However, how phenotypic plasticity affects the association between sexual dimorphism in development time and body size remains unclear. Here, we tracked development time, body size, and body mass throughout the ontogeny of the mosquito Aedes mariae. The larval development of this species is strictly linked to Mediterranean Sea rock-pools, whose highly variable environmental conditions over minimal time frames make this organism-environment system ideal for exploring plasticity-led eco-evolutionary processes. We found differential plasticity between males and females, dissolving the link between dimorphism in development time and body size under increasing temperature and decreasing salinity conditions. These findings contrast with the current hypotheses proposed to explain the origin of the association between sexual bimaturism and sexual size dimorphism, highlighting the condition dependence of sexual dimorphism patterns and the need to consider phenotypic plasticity in future studies on their evolution
Optimal back-off distribution for maximum weighted throughput in CSMA
We consider a generalized version of Carrier-Sense Multiple Access (CSMA), where the contention window size is a constant and the back-off probability distribution can be varied. We address the optimization of a weighted throughput metric, identifying the optimal back-off Probability Density Function (PDF). We give a simple fixed-point algorithm to compute the optimal PDF and prove that the solution is unique. The weighted throughput definition caters for aspects other than the mere channel utilization. It reduces to plain utilization (normalized throughput) when all weights are equal to 1. We also reconnect our result to the classic analysis of saturated non-persistent CSMA, as introduced in the seminal paper by Tobagi and Kleinrock, proving formally that the modeling assumptions of that work, that lead to a Geometric PDF of back-off, actually correspond to the throughput-optimal choice, provided that the ratio of the Geometric PDF is suitably chosen
Relationship between male aging and semen quality: a retrospective study on over 2500 men
Purpose: We aimed to evaluate whether and to what extent an association exists between male aging and worsening of semen parameters and to determine whether a threshold age can be identified above which the decline in semen quality becomes statistically significant. Methods: 2612 men (age: 16–56 years) attending an andrology outpatient clinic for semen analysis and clinical evaluation were studied. Semen analyses were performed according to the ongoing WHO-recommended procedures. Total motile count (TMC) and total progressive motile count (TPMC) were calculated by multiplying total sperm number by total motility and progressive motility, respectively. Results: Significant negative correlations were found between age and total motility (r = − 0.131, p < 0.0001), progressive motility (r = − 0.112, p < 0.0001), TPMC (r = − 0.042, p = 0.037), and normal sperm morphology (r = − 0.053, p = 0.007). All these associations persisted in multivariate regression models adjusted for abstinence time, smoking, history of male accessory gland infections, varicocele and the year in which semen analysis was performed. When comparisons were performed among quartiles of increasing age, the fourth quartile, corresponding to the age group > 40 years, was associated with a significant decrease in total and progressive motility. An earlier decline in the TPMC and percentage of normal forms was also observed. Conclusion: Advancing male age exhibits an independent association with a decrease in the percentage of motile and morphologically normal spermatozoa, with greater evidence from the age of > 40 years. Further studies are warranted to elucidate the mechanisms and clinical reflections of these associations
A new FANET simulator for managing drone networks and providing dynamic connectivity
In the last decade, the attention on unmanned aerial vehicles has rapidly grown, due to their ability to help in many human activities. Among their widespread benefits, one of the most important uses regards the possibility of distributing wireless connectivity to many users in a specific coverage area. In this study, we focus our attention on these new kinds of networks, called flying ad-hoc networks. As stated in the literature, they are suitable for all emergency situations where the traditional networking paradigm may have many issues or difficulties to be implemented. The use of a software simulator can give important help to the scientific community in the choice of the right UAV/drone parameters in many different situations. In particular, in this work, we focus our main attention on the new ways of area covering and human mobility behaviors with the introduction of a UAV/drone behavior model to take into account also drones energetic issues. A deep campaign of simulations was carried out to evaluate the goodness of the proposed simulator illustrating how it works
Fuzzy inference system design for promoting an eco-friendly driving style in IoV domain
With the rise of both embedded technologies and the Internet of Things (IoT) integration, it is increasingly possible to realize complex systems in which, for example, vehicles are connected to the IoT domain capable of interacting directly with applications on mobile or embedded devices. In this work, a Machine to Machine (M2M) based platform able to recognize the driving style will be presented. An embedded device (On-Board Diagnostic (OBD)) has been considered to implement the Internet of Vehicles (IoV) paradigm exporting recognized data to other systems to promote an eco-friendly driving style by suggesting corrective actions to drivers. The architecture consists of the following elements: an on board device able to obtain information regarding speed, acceleration, jerk and fuel consumption, a cloud able to store all collected data, an M2M protocol such as Message Queuing Telemetry Transport (MQTT) to provide scalability to the architecture, and a Fuzzy Inference System to classify user behavior. All these elements are harmonized to achieve the common target of informing users about an Aggressive or Very-Aggressive driving style with the aim of reducing both speed and acceleration. The smart alerting system will promote a more eco-friendly driving style, contributing a reduction in
emissions and fuel consumption. Performance evaluation confirms the efficiency of the proposed classifier and the overall benefits for drivers in fuel consumption reduction
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