Time-course of running treadmill adaptation in novice treadmill runners

ABSTRACT

Studies on running biomechanics and energetics are usually conducted on a treadmill. To ensure that locomotion on a treadmill is comparable to locomotion overground, participants need to be expert in the use of the device. This study aimed to identify the number and duration of sessions needed to obtain stable measurements for spatiotemporal and metabolic parameters in unexperienced treadmill runners. Fourteen male recreational runners performed three 15-min treadmill running trials in different days at a submaximal speed. Spatiotemporal and metabolic parameters were registered at minutes: 5, 10, 15 and their within-trial and between-trial changes were analysed using a two-way repeated measures ANOVA and Bonferroni post-hoc test. Within-trial differences were found in step frequency (decreased over time), Step Length and Contact Time (increased), reaching stability at different time points. Ventilator parameters increased, reaching stability after 5–10 min, while heart rate increased progressively over time. The only between-trial differences were an increase in step length and a decrease in step frequency at min 1, between trials 1 and 3. In conclusion, at least three running trials of 15 min are required to familiarize with the device. The last 5 min of the third trial can be regarded as stable measurements.     

Does social labelling encourage child schooling and discourage child labour in Nepal?

This paper explores the determinants of child labour vis-à-vis child schooling. It further examines the influence of non-governmental organisations (NGOs) which are engaged in social labelling, on the incidence of child labour and schooling trade-off. The empirical results show that the probability of child schooling increases as well as child labour decreases if a carpet firm has adopted a labelling scheme. It can also be shown that labelling NGOs have a significant positive influence on sending the ex-child labourers to school.     

Parental risk attitudes and children's secondary school track choice

Although it is well-known that individuals’ risk attitudes are related to behavioral outcomes such as smoking, portfolio decisions, and educational attainment, there is virtually no evidence of whether parental risk attitudes affect the educational attainment of their dependent children. We add to this literature and examine children's secondary school track choice in Germany where tracking occurs at age ten and has a strong binding character. Using risk indicators for different domains, we mainly find evidence of an inverse relation between parental risk aversion and children's secondary school track, with some heterogeneity depending on whether parents’ risk willingness is modeled separately or jointly, by child gender, or by the risk measure used.     

Are Method Effects Permanent or Ephemeral in Nature? The Case of the Revised Life Orientation Test

This research investigated the nature of the method effect associated with positively worded items of the Life Orientation Test–Revised. In a first cross-sectional study (N?=?11,028) the best fitting model posits 2 factors, representing general optimism and a specific factor associated with positive items. In a second longitudinal study (N?=?203), a unified latent curve latent state–trait model was used to assess the developmental trajectory of the specific factor from 16 to 20 years. This factor contains a prevalence of trait versus state variance, and presents a relationship pattern with external criteria (e.g., depression) that differ from the one involving general optimism.     

A 3D kinematic analysis of breathing patterns in competitive swimmers

Abstract

The purpose of this paper was to understand which differences long-term swimming training can cause on trunk mechanics during breathing and how these differences are related to the years of swimming training. The variations and coordination among trunk compartments were considered as target movement patterns. Video-based plethysmography was utilised for data acquisition and pre-processing. A group of swimmers, who followed a long-term intensive swimming training previously to this study, was compared with a non-swimmer control group. The participants of both groups performed quiet breathing and vital capacity tests. From the compartmental volumes associated with each breathing curves, the relative amplitude and cross-correlation among these volumetric time-varying signals were calculated, in order to analyse the relative partial volume variation and the coordination among trunk compartments involved in respiration. The results of a Mixed-ANOVA test (P ≤ 0.05) revealed higher coefficient of variation (P < 0.001) and correlations among trunk compartments in the swimmers group when vital capacity was performed. Significant linear regression was found between the years of swim training and the coefficients of variation and correlation. The results suggest that after long periods of intensive swim training, athletes might develop specific breathing patterns featuring higher volume variations in the abdominal region and more coordination among compartments involved in forced respiratory tasks such as vital capacity.     

Reflections on historical series of art prices: Reitlinger's data revisited

This note of research argues that Reitlinger's series, and all other series such as Meyer's which are based on official auction sales reports, suffer from significant distortions. This distortion is caused by two main factors: a) the absence of data relating to the identity and the profession of the market agents involved in the transactions recorded in time series; b) the criteria of selection adopted to construct the historical series of prices.     

Information retrieval as semantic inference: a Graph Inference model applied to medical search

This paper presents a Graph Inference retrieval model that integrates structured knowledge resources, statistical information retrieval methods and inference in a unified framework. Key components of the model are a graph-based representation of the corpus and retrieval driven by an inference mechanism achieved as a traversal over the graph. The model is proposed to tackle the semantic gap problem—the mismatch between the raw data and the way a human being interprets it. We break down the semantic gap problem into five core issues, each requiring a specific type of inference in order to be overcome. Our model and evaluation is applied to the medical domain because search within this domain is particularly challenging and, as we show, often requires inference. In addition, this domain features both structured knowledge resources as well as unstructured text. Our evaluation shows that inference can be effective, retrieving many new relevant documents that are not retrieved by state-of-the-art information retrieval models. We show that many retrieved documents were not pooled by keyword-based search methods, prompting us to perform additional relevance assessment on these new documents. A third of the newly retrieved documents judged were found to be relevant. Our analysis provides a thorough understanding of when and how to apply inference for retrieval, including a categorisation of queries according to the effect of inference. The inference mechanism promoted recall by retrieving new relevant documents not found by previous keyword-based approaches. In addition, it promoted precision by an effective reranking of documents. When inference is used, performance gains can generally be expected on hard queries. However, inference should not be applied universally: for easy, unambiguous queries and queries with few relevant documents, inference did adversely affect effectiveness. These conclusions reflect the fact that for retrieval as inference to be effective, a careful balancing act is involved. Finally, although the Graph Inference model is developed and applied to medical search, it is a general retrieval model applicable to other areas such as web search, where an emerging research trend is to utilise structured knowledge resources for more effective semantic search.