Coherence estimate between a random and a periodic signal: Bias, variance, analytical critical values, and normalizing transforms

The present work deals with recent results on the sampling distribution of the magnitude-squared coherence (also called just coherence) estimate between a random (Gaussian) and a periodic signal, in order to obtain analytical critical values, alternative expressions for the probability density function (PDF) as well as the variance and bias of the estimate. A comparison with the more general case of coherence estimation when both signals are Gaussian was also provided. The results indicate that the smaller the true coherence (TC) values the closer both distributions become. The behaviour of variance and bias as a function of the number of data segments and the TC is similar for both coherence estimates. Additionally, the effect of a normalizing function (Fisher's z transform) in the coherence estimated between a random and a periodic signal was also evaluated and normality has been nearly achieved. However, the variance was less equalized in comparison with coherence estimate between two Gaussian signals.     

Open-domain conversational search assistants: the Transformer is all you need

Information Retrieval Journal - On the quest of providing a more natural interaction between users and search systems, open-domain conversational search assistants have emerged, by assisting users...     

Distribution of moisture in reconstructed oil paintings on canvas during absorption and drying: A neutron radiography and NMR study

Moisture is a driving factor in the long-term mechanical deterioration of canvas paintings, as well as for a number of physico–chemical degradation processes. Since the 1990s a number of publications have addressed the equilibrium hygroscopic uptake and the hygro-mechanical deformation of linen canvas, oil paint, animal glue, and ground paint. In order to visualise and quantify the dynamic behaviour of these materials combined in a painting mock-up or reconstruction, we have performed custom-designed experiments with neutron radiography and nuclear magnetic resonance (NMR) imaging. This paper reports how both techniques were used to obtain spatially and temporally resolved information on moisture content, during alternate exposure to high and low relative humidity, or in contact with liquids of varying water activities. We observed how the canvas, which is the dominant component in terms of volumetric moisture uptake, absorbs and dries rapidly, and, due to its low vapour resistance, allows for vapour transfer towards the ground layer. Moisture desorption was generally found to be faster than absorption. The presence of sizing glue leads to a local increase of moisture content. It was observed that lining a painting with an extra canvas results in a damping effect: i.e. absorption and drying are significantly slowed down. The results obtained by NMR are complementary to neutron radiography in that they allow accurate monitoring of water ingress in contact with a liquid reservoir. Quantitative results are in good agreement with adsorption isotherms. The findings can be used for risk analysis of paintings exposed to changing micro-climates or subjected to conservation treatments using water. Future studies addressing moisture-driven deformation of paintings can make use of the proposed experimental techniques.     

American influencies in Brazilian physical education: clues in the specialised periodical press (1932–1950)

This study investigates the American presence and influences in the physical education press to understand the way in which that presence influenced and contributed to the production of a sports culture in the first half of the twentieth century. As historical sources, the study uses periodicals in the field that were published in the period 1932–1950. As a theoretical frame of reference, it uses the repertoire of the New Cultural History in terms of strategy, tactics and devices. It is written in a narrative way, following Ginzburg's style, presenting data and contextualizing them with the historic scene. Clues enabled us to infer that the American presence, which was catalysed by the Brazilian Young Men's Christian Association (YMCA), sought to shape a sports culture from physical education and society. This effort reflected the yearning of Brazilian intellectuals for modernisation and an attempt at cultural colonisation by the government of the USA.     

Development of mechanical engineering curricula at the University of Minho

The implementation of the Bologna protocol in the European Union has set new goals for the whole higher education system as: (a) a quality assessment for university courses; (b) a framework for the exchange of students and academics; and (c) an opportunity for changing the teaching/learning procedures and methodologies. Within the context, the mechanical engineering curricula at the University of Minho have been comprehensively formulated in order to meet these and future challenges and expectations. The whole process has been based upon various cornerstones: the legal framework for the higher education system; the introduction of new learning methodologies and an accurate survey and understanding of the existing strong and week points of the previous experience. For this purpose, a comprehensive evaluation has been carried out with former students and a detailed map has been formulated regarding their professional careers and experiences. Furthermore, a discussion has been carried out in order to define the mission of the graduate in mechanical engineering. In brief, such mission may be referred by his ability to participate in the wealth creation through technology based innovation. Within this context, the curriculum has been structured in order to meet such goals. In addition to strong foundations in physics and mathematics, new subjects are introduced into the curriculum. The whole education is based upon project development which stimulates the students' initiative, responsibility and their ability to integrate knowledge. Throughout the curriculum, students are enrolled into research projects developed in the department and it is expected that a few selected projects may be taken into a quasi industrial stage.     

Meta‐evaluation in clinical anatomy: A practical application of item response theory in multiple choice examinations

The nature of anatomy education has changed substantially in recent decades, though the traditional multiple‐choice written examination remains the cornerstone of assessing students' knowledge. This study sought to measure the quality of a clinical anatomy multiple‐choice final examination using item response theory (IRT) models. One hundred seventy‐six students took a multiple‐choice clinical anatomy examination. One‐ and two‐parameter IRT models (difficulty and discrimination parameters) were used to assess item quality. The two‐parameter IRT model demonstrated a wide range in item difficulty, with a median of ?1.0 and range from ?2.0 to 0.0 (25th to 75th percentile). Similar results were seen for discrimination (median 0.6; range 0.4–0.8). The test information curve achieved maximum discrimination for an ability level one standard deviation below the average. There were 15 items with standardized loading less than 0.3, which was due to several factors: two items had two correct responses, one was not well constructed, two were too easy, and the others revealed a lack of detailed knowledge by students. The test used in this study was more effective in discriminating students of lower ability than those of higher ability. Overall, the quality of the examination in clinical anatomy was confirmed by the IRT models. Anat Sci Educ 3:17–24, 2010. © 2009 American Association of Anatomists.     

Robust regulation for a 3-DOF helicopter via sliding-mode observation and identification

This paper tackles the problem of robust output regulation for a 3-DOF helicopter. The considered system is subjected to model uncertainties and external perturbations. A sliding mode observer is used to estimate the state vector in finite time and identify the uncertainties and perturbations using the information of the equivalent output injection. Based on these estimations a robust regulation controller is designed. Experimental results show the feasibility of this approach.     

In-service teacher training to provide psychosocial support and care in high-risk and high-need schools: school-based intervention partnerships

This article uses a South African case study to argue that postcolonial, emerging economy societies in transition often contain schools characterised as high risk and high need. Such schools require teachers to adapt to roles other than facilitating learning, such as psychosocial support and care, and which requires additional professional development. In the absence of structured teacher professional development programmes, alternatives are required to assist teachers. The paper describes a nine-year partnership between higher education researchers and teachers in high-risk and high-need schools in three South African provinces. The participatory reflection and action (PRA) study served as platform for a school-based intervention to assist in-service teachers to adapt to their additional responsibilities. Thematic analysis was used to identify the ways in which teachers’ adaptation to high risk benefitted from the programme, and self-determination theory is used to argue for a dynamic and interconnected relationship between the teachers’ demonstrated pathways to psychosocial support and care. The article argues that in socio-politically transforming societies where need is high for in-service teacher training and formal structures for teacher professional development may be limited, partnerships between researchers and teachers appear to be useful platforms for school-based interventions to support teacher resilience.     

Training Effects on Older Adults in Information and Communication Technologies Considering Psychosocial Variables

The main aim of this study is to contribute knowledge about the impact of the use of information and communication technologies (ICT) on the self-concept, mood, and quality of life of institutionalized older adults in retirement homes and day care centers (Portuguese institutions). It also studies the influence of independent variables such as age; education; referral to the institution (own initiative, indicated by friends, indicated by family, indicated by social security); attendance schedule; and visits from family and friends. The study comprised 41 participants organized into two groups: 22 older adults in the ICT Group and 19 older adults in the Passive Control Group. There were three evaluation periods: before the onset of intervention and 11 and 22 months after intervention began. The results demonstrate that involvement with information and communication technologies produced positive effects on older adults’ social behavior and their self-perception of physical and environment facets of quality of life. Moreover, they suggest that there is a relationship between psychosocial variables and independent variables.