Maximal lactate steady state in trained adolescent runners

The aims of this study were: (1) to identify the exercise intensity that corresponds to the maximal lactate steady state in adolescent endurance-trained runners; (2) to identify any differences between the sexes; and (3) to compare the maximal lactate steady state with commonly cited fixed blood lactate reference parameters. Sixteen boys and nine girls volunteered to participate in the study. They were first tested using a stepwise incremental treadmill protocol to establish the blood lactate profile and peak oxygen uptake ([Vdot]O₂). Running speeds corresponding to fixed whole blood lactate concentrations of 2.0, 2.5 and 4.0?mmol?·?l^?1 were calculated using linear interpolation. The maximal lactate steady state was determined from four separate 20-min constant-speed treadmill runs. The maximal lactate steady state was defined as the fastest running speed, to the nearest 0.5?km?·?h^?1, where the change in blood lactate concentration between 10 and 20?min was?<0.5?mmol?·?l^?1. Although the boys had to run faster than the girls to elicit the maximal lactate steady state (15.7 vs 14.3?km?·?h^?1, P?<0.01), once the data were expressed relative to percent peak [Vdot]O₂ (85 and 85%, respectively) and percent peak heart rate (92 and 94%, respectively), there were no differences between the sexes (P?>0.05). The running speed and percent peak [Vdot]O₂ at the maximal lactate steady state were not different to those corresponding to the fixed blood lactate concentrations of 2.0 and 2.5?mmol?·?l^?1 (P?>0.05), but were both lower than those at the 4.0?mmol?·?l^?1 concentration (P?<0.05). In conclusion, the maximal lactate steady state corresponded to a similar relative exercise intensity as that reported in adult athletes. The running speed, percent peak [Vdot]O₂ and percent peak heart rate at the maximal lactate steady state are approximated by the fixed blood lactate concentration of 2.5?mmol?·?l^?1 measured during an incremental treadmill test in boys and girls.     

Effect of 6 weeks of endurance training on the lactate minimum speed

The aim of this study was to assess the sensitivity of the lactate minimum speed test to changes in endurance fitness resulting from a 6 week training intervention. Sixteen participants (mean +/- s :age 23 +/- 4 years;body mass 69.7 +/- 9.1 kg) completed 6 weeks of endurance training. Another eight participants (age 23 +/- 4 years; body mass 72.7 +/-12.5 kg) acted as non-training controls. Before and after the training intervention, all participants completed: (1) a standard multi-stage treadmill test for the assessment of VO 2max , running speed at the lactate threshold and running speed at a reference blood lactate concentration of 3 mmol.l -1 ; and (2) the lactate minimum speed test, which involved two supramaximal exercise bouts and an 8 min walking recovery period to increase blood lactate concentration before the completion of an incremental treadmill test. Additionally, a subgroup of eight participants from the training intervention completed a series of constant-speed runs for determination of running speed at the maximal lactate steady state. The test protocols were identical before and after the 6 week intervention. The control group showed no significant changes in VO 2max , running speed at the lactate threshold, running speed at a blood lactate concentration of 3 mmol.l -1 or the lactate minimum speed.In the training group, there was a significant increase in VO 2max (from 47.9 +/- 8.4 to 52.2 +/- 2.7 ml.kg -1 .min -1 ), running speed at the maximal lactate steady state (from 13.3 +/- 1.7 to 13.9 +/- 1.6 km.h -1 ), running speed at the lactate threshold (from 11.2 +/- 1.8 to 11.9 +/- 1.8 km.h -1 ) and running speed at a blood lactate concentration of 3 mmol.l -1 (from 12.5 +/- 2.2 to 13.2 +/- 2.1 km.h -1 ) (all P ? 0.05). Despite these clear improvements in aerobic fitness, there was no significant difference in lactate minimum speed after the training intervention (from 11.0 +/- 0.7 to 10.9 +/- 1.7 km.h -1 ). The results demonstrate that the lactate minimum speed,when assessed using the same exercise protocol before and after 6 weeks of aerobic exercise training, is not sensitive to changes in endurance capacity.     

Race is nowhere and race is everywhere: narratives from black and white South African university students in post‐apartheid South Africa

This paper examines the life history narratives of a group of 12 black and white male and female undergraduate students at a historically white Afrikaans medium university, now undergoing its own transformation in post‐apartheid South Africa. Conceptualizations of identity and discourse across four elements of context, setting, situated activity and self are employed to examine their accounts. Three framing discourses, comprising the official storyline of a rainbow nation and new higher education policies, the formal storyline of institutional change, and the informal space of relationships and interactions are used to analyse student narratives in terms of how they produce, reproduce and transform race and identity. What emerges is a complicated picture in which identities cannot be simply read off either from the official discourse or from colour and culture as the levels of discourse articulate and collide with a history of racial separateness and context and setting, with particular identity effects.

What varieties of men and women now prevail in this society and in this period? And what varieties are coming to prevail? In what ways are they selected and formed, liberated and repressed, made sensitive and blunted? (Mills, 1959 Mills CW (1959) The sociological imagination (London, Oxford University Press) [Crossref] [Google Scholar], p. 7)     

The roles of peritraumatic dissociation, child physical abuse, and child sexual abuse in the development of posttraumatic stress disorder and adult victimization

OBJECTIVE: Previous research has indicated that women who experience childhood physical abuse or childhood sexual abuse are at increased risk for posttraumatic stress disorder (PTSD) and adult victimization. Recently, peritraumatic dissociation (PD) has been suggested as another possible risk factor for PTSD and adult victimization. The purpose of the present study was to investigate the effects of childhood physical and sexual abuse and PD on PTSD and adult victimization. METHOD: A sample of 467 female college students completed questionnaires about childhood and adult sexual and physical abuse experiences, PD, and PTSD symptoms. RESULTS: The combined sexual and physical abuse (CA) and sexual abuse only (SA) groups reported significantly higher numbers of PTSD symptoms than the physical abuse only (PA) and no abuse (NA) groups. The CA and PA groups reported significantly more adult sexual and physical victimization than the SA and NA groups. Across all four groups, higher levels of PD were associated with higher levels of PTSD and adult sexual and physical victimization. CONCLUSIONS: The results of the current study suggest that different types of childhood abuse may lead to different adult problems. The results also indicated that PD may have a broad effect on PTSD development and adult victimization.     

The neural correlates of working memory training in typically developing children

Working memory training improves children's cognitive performance on untrained tasks; however, little is known about the underlying neural mechanisms. This was investigated in 32 typically developing children aged 10–14 years (19 girls and 13 boys) using a randomized controlled design and multi-modal magnetic resonance imaging (Devon, UK; 2015–2016). Training improved working memory performance and increased intrinsic functional connectivity between the bilateral intraparietal sulci. Furthermore, improvements in working memory were associated with greater recruitment of the left middle frontal gyrus on a complex span task. Repeated engagement of fronto-parietal regions during training may increase their activity and functional connectivity over time, affording greater working memory performance. The plausibility of generalizable cognitive benefits from a neurobiological perspective and implications for neurodevelopmental theory are discussed.     

Child forensic interviewing in Children's Advocacy Centers: empirical data on a practice model

OBJECTIVE: Children's Advocacy Centers (CACs) aim to improve child forensic interviewing following allegations of child abuse by coordinating multiple investigations, providing child-friendly interviewing locations, and limiting redundant interviewing. This analysis presents one of the first rigorous evaluations of CACs' implementation of these methods. METHODS: This analysis is part of a quasi-experimental study, the Multi-Site Evaluation of Children's Advocacy Centers, which evaluated four CACs relative to within-state non-CAC comparison communities. Case abstractors collected data on investigation methods in 1,069 child sexual abuse cases with forensic interviews by reviewing case records from multiple agencies. RESULTS: CAC cases were more likely than comparison cases to feature police involvement in CPS cases (41% vs. 15%), multidisciplinary team (MDT) interviews (28% vs. 6%), case reviews (56% vs. 7%), joint police/child protective services (CPS) investigations (81% vs. 52%) and video/audiotaping of interviews (52% vs. 17%, all these comparisons p<.001). CACs varied in which coordination methods they used, and some comparison communities also used certain coordination methods more than the CAC with which they were paired. Eighty-five percent of CAC interviews took place in child-friendly CAC facilities, while notable proportions of comparison interviews took place at CPS offices (22%), police facilities (18%), home (16%), or school (19%). Ninety-five percent of children had no more than two forensic interviews, and CAC and comparison differences on number of interviews were mostly non-significant. CONCLUSIONS: Relative to the comparison communities, these CACs appear to have increased coordination on investigations and child forensic interviewing. The CAC setting was the location for the vast majority of CAC child interviews, while comparison communities often used settings that many consider undesirable. CACs showed no advantage on reducing the number of forensic interviews, which was consistently small across the sample.     

Retrieving and classifying instances of source code plagiarism

Automatic detection of source code plagiarism is an important research field for both the commercial software industry and within the research community. Existing methods of plagiarism detection primarily involve exhaustive pairwise document comparison, which does not scale well for large software collections. To achieve scalability, we approach the problem from an information retrieval (IR) perspective. We retrieve a ranked list of candidate documents in response to a pseudo-query representation constructed from each source code document in the collection. The challenge in source code document retrieval is that the standard bag-of-words (BoW) representation model for such documents is likely to result in many false positives being retrieved, because of the use of identical programming language specific constructs and keywords. To address this problem, we make use of an abstract syntax tree (AST) representation of the source code documents. While the IR approach is efficient, it is essentially unsupervised in nature. To further improve its effectiveness, we apply a supervised classifier (pre-trained with features extracted from sample plagiarized source code pairs) on the top ranked retrieved documents. We report experiments on the SOCO-2014 dataset comprising 12K Java source files with almost 1M lines of code. Our experiments confirm that the AST based approach produces significantly better retrieval effectiveness than a standard BoW representation, i.e., the AST based approach is able to identify a higher number of plagiarized source code documents at top ranks in response to a query source code document. The supervised classifier, trained on features extracted from sample plagiarized source code pairs, is shown to effectively filter and thus further improve the ranked list of retrieved candidate plagiarized documents.     

Tackle and ruck technique proficiency within academy and senior club rugby union

ABSTRACT

This study examined the validity of a tool that assesses tackle and ruck technique in training and established reference data for tackle, ball-carry and ruck technique at different levels of play in rugby union. One hundred and thirty-one amateur rugby union players; 37 senior, 51 first-grade academy and 43 second-grade academy players, participated in a two-on-two contact drill. The drill was filmed and the players’ tackle, ball-carry and ruck technique were assessed using standardized technical criteria. Senior level players scored significantly higher in all three assessments; tackle technique senior vs academy 1^st (p < 0.01, effect size (ES) = 0.7, moderate), senior vs academy 2^nd (p < 0.01, ES = 0.7, moderate); ball-carry technique senior vs academy 1^st (p < 0.01, ES = 0.6, moderate), senior vs academy 2^nd (p < 0.01, ES = 0.8, moderate); ruck technique senior vs academy 1^st (p < 0.01, ES = 0.7, moderate), senior vs academy 2^nd (p < 0.01, ES = 0.4, small). These findings emphasize the importance of developing contact technique to allow players to progress to higher levels, and provide validity to an assessment tool which can facilitate this process.     

Use of Decontextualized Talk Across Story Contexts: How Oral Storytelling and Emergent Reading Can Scaffold Children's Development

This study examined 33 mothers' and preschoolers' oral language skills (decontextualized discourse) across an emergent reading, shared reading, and oral storytelling interaction. The sample comprised primarily African American families from various socioeconomic backgrounds, ranging from Head Start families to middle-income families. Two measures of decontextualized language were assessed—literate language features and type of talk (i.e., a coding scheme categorizing comments/questions on a continuum from contextualized to decontextualized talk). Mothers used more decontextualized language during the oral storytelling interaction versus the other interactions, but children used more during the emergent reading interaction. Mothers with advanced literacy skills were more likely to make decontextualized comments/questions and use mental/linguistic verbs during the interactions. Results are discussed in terms of implications for parent-child home literacy interventions.