Mineralogical-chemical Alteration and Origin of Ignimbritic Stones Used in the Old Cathedral of Nostra Signora di Castro (Sardinia,Italy)

ABSTRACT

The pyroclastic rocks belonging to the Late Eocene-Miocene volcanic activity that occurred in Sardinia between 38 and 15 Ma ago were widely used as construction materials in several Romanesque churches of the easternmost Logudoro area, as well as in large parts of the Sardinia territory. In this work, the ancient Cathedral of Nostra Signora di Castro (twelfth century) was taken as a representative case study. There is no historical or archaeological evidence of ancient quarries. Based on the geochemical, petrographic, and volcanological data on several samples from an extensive field area (approximately 150?km²), a geographical zoning of the volcanics has been recognised. In the Oschiri sector, there are three different sub-zones, which can be identified with different volcanic rocks: less fractionated rocks (Differentation Index ～70–78); intermediately fractionated rocks (D.I. ～76–79); and more fractionated rocks (D.I. ～77–82). To identify the origin of the ignimbrite rocks of the Church of Nostra Signora di Castro, two statistical methods were used: stepwise linear discriminant and canonical analysis. Moreover, to define the geochemical transformation processes induced by the alteration, a comparative study of concentrations of major and trace elements measured by XRF and SEM-EDX analyses on the surface portion and the innermost areas of the stone was made.     

Refining success and dropout in massive open online courses based on the intention–behavior gap

In this paper we present an alternative typology for determining success and dropout in massive open online courses (MOOCs). This typology takes the perspectives of MOOC-takers into account and is based on the their intentions and subsequent behaviour. An explorative study using two MOOCs was carried out to test the applicability of the typology. Following the traditional approach based on course completion to identify educational success, success rates were 6.5 and 5.6%. The success rates from the perspectives of the MOOC-taker were 59 and 70%. These findings demonstrate that merely looking at course completion as a measure for success does not suffice in the context of MOOCs. This change in addressing MOOC success and dropout provides an alternative view and demonstrates the importance of MOOC-takers’ perspectives.     

Analysis of the intraseasonal stability of field test performances in young academy soccer players

This study aimed to observe the intraseasonal stability of anthropometric, technical and functional test results in academy soccer players of different age categories. In total, 103 participants (age range: 7.7–13.4 years) by 5 age categories of the same academy were recruited for this study. Players were submitted to a field-test battery comprising 3 anthropometric measurements (body mass, stature and body mass index), 6 soccer technical tests (to assess the ability of ball control, ball control with the head, pass accuracy, shooting accuracy, dribbling and dribbling with pass) and 3 functional tests (countermovement jump with the hands on the hip, countermovement jump with free hands and 15-m linear sprint) that was administered in 4 test sessions during the same season. Though anthropometric results showed a clear increment in each age category across the season, the fluctuation of technical test results depended on age category and test session. Moreover, a significant increase in the results of functional tests was observed in most of the age categories, in particular, for the assessment of lower power limb. In conclusion, collecting repeated intraseason measurements permits the identification of players’ fluctuations of performance across the season and allows coaches to make frequent adjustments of their programmes.     

Quantification of energy expenditure of recreational football

ABSTRACT

There is a strong relationship between low physical activity level and cardiovascular diseases (CVD). The popularity of football may be used to promote physical activity and previous evidence has shown it is effective to decrease the risk of CVD. However, the energy expenditure (EE) of recreational football is not well known but it is crucial to develop preventive health programmes.

Fifteen sedentary middle-aged male participants were involved (mean ± SDs; age 43.9 ± 3.1 years, weight 83.0 ± 13.6 kg, height 174.9 ± 6.8 cm). EE was estimated from the heart rate (HR)-VO₂ relation during 1-h 5-a-side matches (futsal). Participants covered 3412 ± 381 m in 52 ± 2 min, at an average HR of 85 ± 2% of maximum HR. Estimated EE during a recreational futsal match was 634 ± 92 kcal. One futsal recreational match corresponds to about 50% of American College of Sport Medicine recommended physical activity quantity per week. Based on this estimation: once, twice and 3 sessions per week are equivalent to 50% (634 kcal), 100% (1268 kcal) and 150% (1902 kcal), respectively, of EE suggested in international guidelines. This EE estimation may have important implications for designing recreational football training protocols in health programmes and dose response studies.     

Design procedure for thin three-layer plates made of a depleted material

The efficiency of a long-span structure relies on how material is locally distributed within a fixed structural shape. In this paper a design procedure for thin plates made of three layers of a depleted material subject to a distributed vertical load is proposed. The investigation is driven by the idea of the optimal material organization and has the objective of maximizing the overall stiffness/weight ratio of the structure. Two microstructural architectures of the media are considered: a porous solid structure and a truss arrangement. For each type of microstructure the flexural stiffness has been correlated to the level of depletion by the use of a power law function by setting very few parameters. Finally, invoking the principles of structural homogenization theory, the global flexural response of the plate has also been calculated. The validity of the method is demonstrated by comparing the analytical results with those obtained by a numerical finite element simulation of the structure based on a detailed model of the media.     

Retrospective cytological evaluation of indeterminate thyroid nodules according to the British Thyroid Association 2014 classification and comparison of clinical evaluation and outcomes

The cytology of 130 indeterminate nodules (Thy 3) was retrospectively reviewed according to the British Thyroid Association 2014 classification. Nodules were divided into Thy 3a (atypical features) and Thy 3f (follicular lesion) categories. Histology was available as a reference for 97 nodules. Pre-surgical evaluations comprised biochemical tests, color-Doppler ultrasonography (US), semi-quantitative elastography-US (USE), contrast-enhanced US (CEUS), and mutation analysis from cytological slides. Thyroid malignancy was the final diagnosis for 19% of surgically-treated nodules. No statistically significant difference in the risk of malignancy was found between Thy 3a (26%) and Thy 3f (14%) nodules. Histology of the Thy 3a and Thy 3f nodules showed a higher incidence of Hurtle cell adenomas in Thy 3f (29%) than in Thy 3a (3%) nodules (P=0.01). The only pre-surgical difference concerned the BRAF V600E mutation, which was positive in some Thy 3a but not in any Thy 3f nodules (P=0.04). Receiver-operating characteristic (ROC) analysis was used to obtain cut-off values from US (score), USE (ELX 2/1 strain index), and CEUS (time-topeak index and peak index) data. The cut-off values were similar for Thy 3a and Thy 3f nodules. Data showed that malignancy can be suspected if the US score is >2, ELX 1/2 strain index >1, time-to-peak index >1, and peak index <1. In a sub-group of 24 revised nodules (12 Thy 3a and 12 Thy 3f) with histology as a reference, the diagnostic power of cumulative pre-surgical analysis by means of US, USE, and CEUS showed high positive and negative predictive values (83% and 100%, respectively) for the presence of malignancy in Thy 3a and Thy 3f nodules. In conclusion, in our series of revised Thy 3 nodules, malignancy was low and displayed no significant differences between Thy 3a and Thy 3f categories. The use of cut-offs based on histology as a reference could reduce surgery. Our data support the conviction that, in mutation-negative Thy 3a and Thy 3f nodules, observation should be the first choice when not all instrumental results are suspect.     

Teachers’ perceptions of effective teaching: a comparative study of elementary school teachers from China and the USA

This international study investigated Chinese and American elementary school teachers’ perceptions of effective teaching. The sample comprised Chinese (n?=?108) and US (n?=?110) participating teachers. The Effective Teaching Quality Survey (ETQS) was adopted for this comparative education research, an instrument that operationalized Stronge’s effective teaching theoretical framework. Research questions that guided this study were as follows: (1) what are the differences between the USA and China’s elementary school teachers’ perceptions regarding effective teaching? And (2) when comparing teaching experience, school location, and effective/ineffective teachers, what are the differences between the USA and China’s elementary school teachers’ perceptions on effective teaching? Statistically significant results were found when comparing nationality, teaching experience, school location, and effective/ineffective teaching. How these results related to the US and Chinese educational contexts with respect teaching and learning are discussed.     

E–Learning in Hong Kong: comparing learning outcomes in online multimedia and lecture versions of an introductory computing course

This paper evaluates the effectiveness of Web–based, highly interactive, and multimedia–rich e–learning materials by comparing students' learning outcomes in the lecture and online versions of an introductory computing course. The course versions differed only in that face–to–face lectures were replaced with e–learning modules in the online course; the other course elements (laboratory sessions, use of computer–mediated communications, examinations) were the same. The e–learning trial took place at the Hong Kong University of Science and Technology, where the first author taught the lecture course to 105 students, and the online course to 180 and 129 students in the following semesters. The lecture and online students achieved comparable factual learning outcomes and the online students outperformed the lecture students in applied–conceptual learning. Findings suggest that the use of carefully designed interactive e–learning modules fosters higher–order learning outcomes.