SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Scales

34

At the college level, the effectiveness of active-learning interventions is typically measured at the broadest scales: the achievement or retention of all students in a course. Coarse-grained measures like these cannot inform instructors about an intervention’s relative effectiveness for the different student populations in their classrooms or about the proximate factors responsible for the observed changes in student achievement. In this study, we disaggregate student data by racial/ethnic groups and first-generation status to identify whether a particular intervention-increased course structure-works better for particular populations of students. We also explore possible factors that may mediate the observed changes in student achievement. We found that a “moderate-structure” intervention increased course performance for all student populations, but worked disproportionately well for black students-halving the black-white achievement gap-and first-generation students-closing the achievement gap with continuing-generation students. We also found that students consistently reported completing the assigned readings more frequently, spending more time studying for class, and feeling an increased sense of community in the moderate-structure course. These changes imply that increased course structure improves student achievement at least partially through increasing student use of distributed learning and creating a more interdependent classroom community.

Concepts: Better, Education, Intervention, Student, Classroom, Relative effectiveness factor, Scales, Hood

27

Assessing functional diversity from space can help predict productivity and stability of forest ecosystems at global scale using biodiversity-ecosystem functioning relationships. We present a new spatially continuous method to map regional patterns of tree functional diversity using combined laser scanning and imaging spectroscopy. The method does not require prior taxonomic information and integrates variation in plant functional traits between and within plant species. We compare our method with leaf-level field measurements and species-level plot inventory data and find reasonable agreement. Morphological and physiological diversity show consistent change with topography and soil, with low functional richness at a mountain ridge under specific environmental conditions. Overall, functional richness follows a logarithmic increase with area, whereas divergence and evenness are scale invariant. By mapping diversity at scales of individual trees to whole communities we demonstrate the potential of assessing functional diversity from space, providing a pathway only limited by technological advances and not by methodology.

Concepts: Species, Method acting, Ecosystem, Tree, Methodology, Map, Scale, Scales

27

Abstract The ergogenic effect of caffeine on sports performance focuses predominantly on endurance sports (Doherty & Smith, 2004 ) with little research on intermittent high intensity sports. This study aimed to explore the effect of caffeine ingestion on skill maintenance following fencing simulated exercise. Eleven competitive fencers participated (four female; seven male; age 33 ± 6.5 years). Following a maximal test to exhaustion, fencers completed two trials assessing accuracy and reaction times (Stroop test) before and after a fatiguing protocol designed to simulate the demands of a fencing competition. Skill testing involved 30 lunges to hit a target. 500 ml placebo or 3 mg · kg(-1) caffeine supplemented drink was administered after the initial reaction and skill tests in a single-blind crossover design. The fatiguing protocol involved simulating six fights with 6-minute rests between each. Fencers rated their perceived exertion (arm, legs, overall) using the Borg scale. There was no overall effect of caffeine on total skill score (P = 0.40), however there was a tendency for fewer misses with caffeine (P = 0.10). Caffeine had no effect on the Stroop Test. Caffeine produced significantly lower perceived fatigue for overall (P < 0.01). These results provide some support for caffeine producing maintenance of skill and reducing perceived fatigue during fencing.

Concepts: Clinical trial, Exercise, Perception, Simulation, Operations research, Placebo, Simulated reality, Scales

25

Inexpensive software applications designed to teach reading, writing, mathematics, and other academic areas have become increasingly popular. Although previous research has demonstrated the potential efficacy of such applications, there is a paucity of research that compares applications instruction (AI) with traditional teacher-directed instruction (TDI), and the relative effectiveness and efficiency of these instructional approaches remains largely unknown. This study used an alternating treatment design to compare academic engagement and outcomes (i.e., word identification and reading fluency) during an AI condition and a TDI condition for four students with learning disabilities (LD) attending a charter school. Instructional conditions (i.e., TDI, AI) were randomly alternated 7 times each, for a total of 14 instructional sessions. Results indicated that both approaches fostered high levels of engagement although students were more engaged during AI. With regard to academic performance, visual and quantitative analysis suggest that TDI was more effective than AI in terms of passage fluency and word identification. Students completed social validity rating scales to examine instructional preference. Results indicated that both approaches, TDI and AI, were popular with the students.

Concepts: Effect, Effectiveness, Education, Educational psychology, Efficacy, Binary relation, Scales, Word processor

5

The eHealth Literacy Scale (eHEALS) is one of only a few available measurement scales to assess eHealth literacy. Perhaps due to the relative paucity of such measures and the rising importance of eHealth literacy, the eHEALS is increasingly a choice for inclusion in a range of studies across different groups, cultures, and nations. However, despite its growing popularity, questions have been raised over its theoretical foundations, and the factorial validity and multigroup measurement properties of the scale are yet to be investigated fully.

Concepts: Psychometrics, Scales

5

BACKGROUND: older people are at an increased risk of adverse outcomes following attendance at acute hospitals. Screening tools may help identify those most at risk. The objective of this study was to compare the predictive properties of five frailty-rating scales.Method: this was a secondary analysis of a cohort study involving participants aged 70 years and above attending two acute medical units in the East Midlands, UK. Participants were classified at baseline as frail or non-frail using five different frailty-rating scales. The ability of each scale to predict outcomes at 90 days (mortality, readmissions, institutionalisation, functional decline and a composite adverse outcome) was assessed using area under a receiver-operating characteristic curve (AUC). RESULTS: six hundred and sixty-seven participants were studied. Frail participants according to all scales were associated with a significant increased risk of mortality [relative risk (RR) range 1.6-3.1], readmission (RR range 1.1-1.6), functional decline (RR range 1.2-2.1) and the composite adverse outcome (RR range 1.2-1.6). However, the predictive properties of the frailty-rating scales were poor, at best, for all outcomes assessed (AUC ranging from 0.44 to 0.69). CONCLUSION: frailty-rating scales alone are of limited use in risk stratifying older people being discharged from acute medical units.

Concepts: Cohort study, Epidemiology, Medical terms, Medical statistics, Actuarial science, Relative risk, Outcome, Scales

4

A key question in clarifying human-environment interactions is how dynamic complexity develops across integrative scales from molecular to population and global levels. Apart from its public health importance, measles is an excellent test bed for such an analysis. Simple mechanistic models have successfully illuminated measles dynamics at the city and country levels, revealing seasonal forcing of transmission as a major driver of long-term epidemic behavior. Seasonal forcing ties closely to patterns of school aggregation at the individual and community levels, but there are few explicit estimates of school transmission due to the relative lack of epidemic data at this scale. Here, we use data from a 1904 measles outbreak in schools in Woolwich, London, coupled with a stochastic Susceptible-Infected-Recovered model to analyze measles incidence data. Our results indicate that transmission within schools and age classes is higher than previous population-level serological data would suggest. This analysis sheds quantitative light on the role of school-aged children in measles cross-scale dynamics, as we illustrate with references to the contemporary vaccination landscape.

Concepts: Public health, Epidemiology, Infectious disease, Vaccine, Model theory, Dynamics, Musical scale, Scales

4

Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth’s lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas ≥8.5 km(2) are power-law distributed with a tail exponent (τ = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (τ = 2.05; d = 4/3). Lakes <8.5 km(2) are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales.

Concepts: Scientific method, Lake, Hypothesis, Distribution, Theory, Explanation, Fractal, Scales

3

Our understanding of the genetic basis of disease has evolved from descriptions of overall heritability or familiality to the identification of large numbers of risk loci. One can quantify the impact of such loci on disease using a plethora of measures, which can guide future research decisions. However, different measures can attribute varying degrees of importance to a variant. In this Analysis, we consider and contrast the most commonly used measures - specifically, the heritability of disease liability, approximate heritability, sibling recurrence risk, overall genetic variance using a logarithmic relative risk scale, the area under the receiver-operating curve for risk prediction and the population attributable fraction - and give guidelines for their use that should be explicitly considered when assessing the contribution of genetic variants to disease.

Concepts: Genetics, Epidemiology, Virus, Relative risk, Population genetics, Order of magnitude, Variant type, Scales

2

The question of whether species co-occurrence is random or deterministic has received considerable attention, but little is known about how anthropogenic disturbance mediates the outcomes. By combining experiments, field surveys and analysis against null models, we tested the hypothesis that anthropogenic habitat modification disrupts species co-occurrence in stream invertebrates across spatial scales. Whereas communities in unmodified conditions were structured deterministically with significant species segregation, catchment-scale conversion to agriculture and sediment deposition at the patch- or micro-habitat scale apparently randomised species co-occurrences. This shift from non-random to random was mostly independent of species richness, abundance and spatial scale. Data on community-wide life-history traits (body-size, dispersal ability and predatory habits) and beta-diversity indicated that anthropogenic modification disrupted community assembly by affecting biotic interactions and, to a lesser extent, altering habitat heterogeneity. These data illustrate that the balance between predictable and stochastic patterns in communities can reflect anthropogenic modifications that not only transcend scales but also change the relative forces that determine species coexistence. Research into the effects of habitat modification as a key to understanding global change should extend beyond species richness and composition to include species co-occurrence, species interactions and any functional consequences. This article is protected by copyright. All rights reserved.

Concepts: Sediment, Force, All rights reserved, Null hypothesis, Musical scale, Copyright, Determinism, Scales