The effective use of student time: a stochastic frontier production function case study

The relationship between student study time allocation and examination performance is little understood. We model the allocation of student time into formal study (lectures and classes) and self study and its relationship to university examination scores using a stochastic frontier production function. This case study uses unique time budget data and detailed personal records from one university in Spain. The results suggest that, within the formal system of teaching in Spain, both formal study and self study are significant determinants of exam scores but that the former may be up to four times more important than the latter. We also find that self study time may be insignificant if ability bias is corrected for.     

Non-linear resistance training reduces inflammatory biomarkers in persons living with HIV: A randomized controlled trial

The purpose of this study is to analyse the effect of 12 weeks of non-linear resistance training (NLRT) on anthropometry, muscle strength and inflammatory biomarkers in persons infected with human immunodeficiency virus (PIHIV). Thirty previously sedentary PIHIVs were randomized into the NLRT (n?=?15) and control (CON, n?=?15) groups. NLRT group were submitted to 12 weeks of training, whereas the CON group maintained their daily habits. At baseline and after 12 weeks, both groups underwent anthropometric evaluations and blood sampling for the analysis of inflammatory biomarkers. Analysis of covariance using preintervention values as covariate was performed to determine the effects of exercise on anthropometry, muscle strength, cytokines levels and T cells. Significance was set at p?p?p p?=?.009), blood levels of interleukin (IL)-1β (p?=?.029), IL-6 (p?=?.005), IL-8 (p?=?.010), and tumour necrosis factor (TNF)-α (p?=?.001) and an increase in muscle strength (p?p?=?.030) and CD4⁺ (p?=?.004) and CD8⁺ (p?相似文献   

Risk Assessment and Preservative Measures for Volatile Organic Compounds in Museum Showcases

ABSTRACT

The first step in preservative measures for artworks in airtight showcases is the exclusion of outgassing from construction materials or, at least, limitation of the emissions to a minimum acceptable level if the volatile organic compounds (VOCs) generated may be qualified as harmless. Once it is ascertained that the objects in the showcases are responsible for VOC emissions, a step forward becomes necessary, implying showcase ventilation with air flowing through active sorbent materials. Solid phase micro-extraction (SPME) followed by GC separation and MS identification has been applied for checking the outgassing characteristics of different types of materials used for the construction of airtight showcases, and the method was found particularly attractive in terms of speed and sensitivity, suitable for measurements in presence of low-emitting materials. Sampling could also be done in the case interiors, thus making possible detection and recognition of emissions from art objects within a case. A comprehensive preventive conservation scheme has been further devised by means of active air circulation within the showcase and functional sorbent materials along the flow, for complete suppression of gaseous compounds. Control of the compounds in the air flow and of their filtration efficacy was achieved by direct sampling, also using SPME fibers. Continuous monitoring of the air quality in the showcases has been developed with insertion of a photoionization detector capable of detecting the VOCs in the air by inducing molecular ionization, and measuring the generated photocurrent. The system is not selective, but gives the total concentration, reaching ppb sensitivity with high-quality data. In addition it includes temperature and humidity sensors, making the whole a useful instrument for environment control.     

Verbal Short‐Term Memory Underlies Typical Development of “Thought Organization” Measured as Speech Connectedness

Formal thought organization obtained from free speech, a key feature for psychiatric evaluations, has been poorly investigated during typical development. Computational tools such as speech graph connectedness (LSC) currently allow for an accurate quantification in naturalistic settings. LSC's typical development is better predicted by years of education than by age. Among beginning readers, the LSC of stories composed of short‐term memory predicted reading independently from IQ. Here we set out to test a longitudinal sample (6–8 years old, n = 45, followed for 2 years) to verify whether the LSC is predictive of various memory measures, and whether such relations can explain the correlation with reading. The LSC was specifically correlated with verbal short‐term memory performance. The results support the notion that the short‐term storage of verbal information is necessary to plan a story. Given the limited sample size, the relationship of this interaction with reading remains inconclusive.     

A multilevel hypernetworks approach to capture meso-level synchronisation processes in football

ABSTRACT

Understanding team behaviours in sports performance requires understanding the interdependencies established between their levels of complexity (micro-meso-macro). Previously, most studies examined interactions emerging at micro- and macro-levels, thus neglecting those emerging at a meso-level (reveals connections between player and team levels, depicted by the emergence of coordination in specific sub-groups of players–simplices during performance). We addressed this issue using the multilevel hypernetworks approach, adopting a cluster-phase method, to record player-simplice synchronies in two performance conditions where the number, size and location of goals were manipulated (first-condition: 6 × 6 + 4 mini-goals; second-condition: Gk + 6 × 6 + Gk). We investigated meso-level coordination tendencies, as a function of ball-possession (attacking/defending), field-direction (longitudinal/lateral) and teams (Team A/Team B). Generally, large synergistic relations and more stable patterns were observed in the longitudinal direction of the field than the lateral direction for both teams, and for both game phases in the first condition. The second condition displayed higher synchronies and more stable patterns in the lateral direction than the longitudinal plane for both teams, and for both game phases. Results suggest: (i) usefulness of hypernetworks in assessing synchronisation of teams at a meso-level; (ii) coaches may consider manipulating these task constraints to develop levels of local synchronies within teams.     

Constitutive Pluralism of Chemistry: Thought Planning, Curriculum, Epistemological and Didactic Orientations

Maybe the most difficult aspect of thinking about chemistry arises from the fact that chemistry isn’t an homogeneous subject. As a central science, it draws on a range of philosophical perspectives which in turn can result in different cognitive, learning and teaching styles in chemical education. This idea, apparently non-controversial, needs to be validated by more research. Without assuming this constitutive pluralism, describing it, and determining it, it becomes difficult to think of curricular goals and content. Thus, if we intend to improve the teaching of chemistry it is necessary, first, to assume explicitly this constitutive pluralism, then to map it in order to find the guiding principles: first for the mind (thought process), then for the curriculum and finally for the teaching, in such a way that it is as close as possible to the chemical way of operating and thinking. This is the aim of this paper. It reports the authors’ experiences in drafting structural ideas and planning for the subject “didactic of chemistry” based on the philosophy of chemistry at the University of Porto in Portugal.     

Activity-related typologies and longitudinal change in physical activity and sedentary time in children and adolescents: The UP&DOWN Study

BackgroundChildren and adolescents can be distinguished by different typologies (clusters) of physical activity and sedentary behavior. How physical activity and sedentary behaviors change over time within different typologies is not known. This study examined longitudinal changes in physical activity and sedentary time among children and adolescents with different baseline typologies of activity-related behavior.MethodsIn this longitudinal study (3 annual time points) of children (n = 600, age = 9.2 ± 0.4 years (mean ± SD), 50.3% girls) and adolescents (n = 1037, age = 13.6 ± 1.7 years, 48.4% girls), participants were recruited in Spain in 2011–2012. Latent class analyses identified typologies based on self-reported screen, educational, social and relaxing sedentary behaviors, active travel, muscle strengthening activity, and sport at baseline. Within each typology, linear mixed growth models explored longitudinal changes in accelerometer-derived moderate-to-vigorous physical activity and sedentary time, as well as time by class interactions.ResultsThree typologies were identified among children (“social screenies”, 12.8%; “exercisers”, 61.5%; and “non-sporty active commuters”, 25.7%) and among adolescents (“active screenies”, 43.5%; “active academics”, 35.0%; and “non-sporty active commuters”, 21.5%) at baseline. Sedentary time increased within each typology among children and adolescents, with no significant differences between typologies. No changes in physical activity were found in any typology among children. In adolescents, physical activity declined within all typologies, with “non-sporty active commuters” declining significantly more than “active screenies” over 3 years.ConclusionThese results support the need for intervention to promote physical activity and prevent increases in sedentary time during childhood and adolescence. Adolescents characterized as “non-sporty active commuters” may require specific interventions to maintain their physical activity over time.     

Relationship Between Educational Resources and School Achievement: A Mixed Method Intra-District Analysis

This study examines the relationship between educational resources (fiscal, personnel and facilities) and school achievement within a large urban/suburban elementary school district. A sequential mixed methods approach reveals inequitable resource allocation trends and patterns between schools within a school district by producing different student outcomes. The educational resources positively correlated to higher school achievement are: higher teacher salaries, newer schools, more multi-purpose space per pupil and less portable classrooms. Without question, White students receive more of these resources than Latino students, low-income students and English Language learners. This study also conducts a multiple comparative case study analysis comparing between Title I and non-Title I schools, within Title I schools and within non-Title I schools. The study contains policy and practice implications to improve opportunity and school achievement in urban/suburban school districts.