Electromagnetic topology: Characterization of internal electromagnetic coupling

The main principles are presented of a method dealing with the resolution of electromagnetic internal problems: Electromagnetic Topology. A very interesting way is to generalize the multiconductor transmission line network theory to the basic equation of the Electromagnetic Topology: the BLT equation. This generalization is illustrated by the treatment of an aperture as a four port junction. Analytical and experimental derivations of the scattering parameters are presented. These concepts are used to study the electromagnetic coupling in a scale model of an aircraft, and can be seen as a convenient means to test internal electromagnetic interference

DESLOCAMENTO, SENSIBILIDADE AO REFORÇO E MÚLTIPLAS ALTERNATIVAS

When rats search for food in eight alternatives concurrently available and climb barriers to travel from one site to another, the distributions of times and responses often lag behind those of the reinforcers. This result may reflect the way in which the barriers are introduced into the situation. The present experiment explored this possibility with rats. Concurrent schedules of reinforcement with random interval components of different values provided food in eight levers mounted in four chambers connected to a central platform. First, the rats were allowed to enter the chambers and switch from one lever to another without restrictions. Then access to the chambers was obstructed and the levers separated from one another by 300-mm-high barriers. Finally, the height of the barriers was increased from 300 to 700 mm. The shortest visit times, giving-up times, and giving-up responses were produced when rats visited the levers without restrictions. With the barriers in place these measures increased, reaching higher values when barrier height was increased. For responses, sensitivity to reinforcement, as estimated by the parameter s of the generalized matching law, increased with increasing travel requirement, indicating a tendencytoward overmatching. However, for time allocation only one rat showed the same tendency.Key words: Choice, multiple alternatives, travel, sensitivity, ratsQuando ratos procuram por alimento em oito alternatives disponíveis concorrentemente e saltam barreiras para se deslocar de um local para outro, as distribuições de tempo e respostas geralmente ficam aquém das distribuições de reforços. Esse resultado pode refletir a maneira pela qual as barreiras são introduzidas na situação. O presente experimento explorou essa possibilidade com ratos. Esquemas concorrentes de reforço com components de intervalo randômico de diferentes durações forneceram alimento em oito barras instaladas em quatro câmaras experimentais conectadas a uma plataforma central. Primeiro, os ratos podiam entrar nas câmaras e mudar de uma barra para a outra sem restrições. Depois, o acesso às câmaras foi obstruído e as barras foram separadas uma da outra por barreiras de 300 mm de altura. Finalmente, as oito barreiras aumentaram de 300 para 700 mm. Os tempos de visita e de mudança e a quantidade de respostas de mudança foram menores quando os ratos visitavam as barras sem restrições. Com a introdução das barreiras, essas medidas aumentaram, atingindo os maiores valores quando a altura das barreiras aumentou. Para as respostas, a sensibilidade ao reforçamento, estimada pelo parâmetro s da lei generalizada da igualação, aumentou com aumentos no requisito para o deslocamento, indicando uma tendência à superigualação. No entanto, apenas um rato mostrou a mesma tendência para a alocação de tempo. Palavras-chave: Escolha, múltiplas alternativas, deslocamento, sensibilidade, rato

Detection of advanced persistent threat using machine-learning correlation analysis

As one of the most serious types of cyber attack, Advanced Persistent Threats (APT) have caused major concerns on a global scale. APT refers to a persistent, multi-stage attack with the intention to compromise the system and gain information from the targeted system, which has the potential to cause significant damage and substantial financial loss. The accurate detection and prediction of APT is an ongoing challenge. This work proposes a novel machine learning-based system entitled MLAPT, which can accurately and rapidly detect and predict APT attacks in a systematic way. The MLAPT runs through three main phases: (1) Threat detection, in which eight methods have been developed to detect different techniques used during the various APT steps. The implementation and validation of these methods with real traffic is a significant contribution to the current body of research; (2) Alert correlation, in which a correlation framework is designed to link the outputs of the detection methods, aims to identify alerts that could be related and belong to a single APT scenario; and (3) Attack prediction, in which a machine learning-based prediction module is proposed based on the correlation framework output, to be used by the network security team to determine the probability of the early alerts to develop a complete APT attack. MLAPT is experimentally evaluated and the presented sy

A state-of-the-art analysis of the dwarf irregular galaxy NGC 6822

We present a detailed photometric study of the dwarf irregular galaxy NGC 6822 aimed at investigating the properties of its stellar populations and, in particular, the presence of stellar radial gradients. Our goal is to analyse the stellar populations in six fields, which cover the whole bar of this dwarf galaxy. We derived the quantitative star formation history (SFH) of the six fields using the IAC method, involving IAC-pop/MinnIAC codes. The solutions we derived show an enhanced star formation rate (SFR) in Fields 1 and 3 during the past 500 Myr. The SFRs of the other fields are almost extinguished at very recent epochs and. We study the radial gradients of the SFR and consider the total mass converted into stars in two time intervals (between 0 and 0.5 Gyr ago and between 0.5 and 13.5 Gyr ago). We find that the scale lengths of the young and intermediate-to-old populations are perfectly compatible, with the exception of the young populations in Fields 1 and 3. The recent SF in these two fields is greater than in the other ones. This might be an indication that in these two fields we are sampling incipient spiral arms. Further evidence and new observations are required to prove this hypothesis. In addition, we derived the age-metallicity relations. As expected, the metallicity increases with time for all of the fields. We do not observe any radial gradient in the metallicity.Comment: 9 pages, 11 figures, Accepted to A&

Cultural impacts on e-learning systems' success

E-learning systems are enablers in the learning process, strengthening their importance as part of the educational strategy. Understanding the determinants of e-learning success is crucial for defining instructional strategies. Several authors have studied e-learning implementation and adoption, and various studies have addressed e-learning success from different perspectives. However, none of these studies have verified whether students' cultural characteristics, such as individualism versus collectivism (individualism/collectivism), play a determinant role in the perceived e-learning success. This study provides a deeper understanding of the impact of students' cultural characteristics, for individualism/collectivism, on the perceived outcomes of e-learning systems use. This study proposes an e-learning systems success model that includes a cultural construct, individualism/collectivism. This paper reports an empirical study developed through an electronic survey distributed to higher education students belonging to various learning levels and from various universities. The study applies quantitative methods to obtain results. Our findings demonstrate that learners' perceived individual impact is positively influenced by their satisfaction and e-learning systems' use. Results demonstrate the determinant role of individualism/collectivism on individual and organizational impacts. Students influenced by collective culture perceive more individual and organizational impacts than individualistic culture students. Individualism/collectivism also moderates the users' perceived satisfaction on individual impact, and from individual impacts to organizational impacts. The result shows that for the students with a stronger individualistic culture, satisfaction plays a central role in the way they assess the individual impacts, and individual impacts on organizational impacts. This empirical research discusses the theoretical and practical implications.info:eu-repo/semantics/acceptedVersio

A WFC3/HST view of the three stellar populations in the Globular Cluster NGC6752

Multi-band Hubble Space Telescope photometry reveals that the main sequence, sub-giant, and the red giant branch of the globular cluster NGC6752 splits into three main components in close analogy with the three distinct segments along its horizontal branch stars. These triple sequences are consistent with three stellar groups: a stellar population with a chemical composition similar to field halo stars (population a), a population (c) with enhanced sodium and nitrogen, depleted carbon and oxygen and enhanced helium abundance (Delta Y ~0.03), and a population (b) with an intermediate (between population a and c) chemical composition and slightly helium enhanced (Delta Y ~0.01). These components contain ~25% (population a), ~45% (population b), and ~30% (population c) of the stars. No radial gradient for the relative numbers of the three populations has been identified out to about 2.5 half mass radii.Comment: 42 pages, 24 figures, accepted for publication in Ap