A novel device using the Nordic hamstring exercise to assess eccentric knee flexors strength : a reliability and retrospective injury study

STUDY DESIGN: Reliability and case-control injury study. OBJECTIVES: 1) To determine if a novel device, designed to measure eccentric knee flexors strength via the Nordic hamstring exercise (NHE), displays acceptable test-retest reliability; 2) to determine normative values for eccentric knee flexors strength derived from the device in individuals without a history of hamstring strain injury (HSI) and; 3) to determine if the device could detect weakness in elite athletes with a previous history of unilateral HSI. BACKGROUND: HSIs and reinjuries are the most common cause of lost playing time in a number of sports. Eccentric knee flexors weakness is a major modifiable risk factor for future HSIs, however there is a lack of easily accessible equipment to assess this strength quality. METHODS: Thirty recreationally active males without a history of HSI completed NHEs on the device on 2 separate occasions. Intraclass correlation coefficients (ICCs), typical error (TE), typical error as a co-efficient of variation (%TE), and minimum detectable change at a 95% confidence interval (MDC95) were calculated. Normative strength data were determined using the most reliable measurement. An additional 20 elite athletes with a unilateral history of HSI within the previous 12 months performed NHEs on the device to determine if residual eccentric muscle weakness existed in the previously injured limb. RESULTS: The device displayed high to moderate reliability (ICC = 0.83 to 0.90; TE = 21.7 N to 27.5 N; %TE = 5.8 to 8.5; MDC95 = 76.2 to 60.1 N). Mean±SD normative eccentric flexors strength, based on the uninjured group, was 344.7 ± 61.1 N for the left and 361.2 ± 65.1 N for the right side. The previously injured limbs were 15% weaker than the contralateral uninjured limbs (mean difference = 50.3 N; 95% CI = 25.7 to 74.9N; P < .01), 15% weaker than the normative left limb data (mean difference = 50.0 N; 95% CI = 1.4 to 98.5 N; P = .04) and 18% weaker than the normative right limb data (mean difference = 66.5 N; 95% CI = 18.0 to 115.1 N; P < .01). CONCLUSIONS: The experimental device offers a reliable method to determine eccentric knee flexors strength and strength asymmetry and revealed residual weakness in previously injured elite athletes.

Monitoring of complex systems of interacting dynamic systems

Increases in functionality, power and intelligence of modern engineered systems led to complex systems with a large number of interconnected dynamic subsystems. In such machines, faults in one subsystem can cascade and affect the behavior of numerous other subsystems. This complicates the traditional fault monitoring procedures because of the need to train models of the faults that the monitoring system needs to detect and recognize. Unavoidable design defects, quality variations and different usage patterns make it infeasible to foresee all possible faults, resulting in limited diagnostic coverage that can only deal with previously anticipated and modeled failures. This leads to missed detections and costly blind swapping of acceptable components because of one’s inability to accurately isolate the source of previously unseen anomalies. To circumvent these difficulties, a new paradigm for diagnostic systems is proposed and discussed in this paper. Its feasibility is demonstrated through application examples in automotive engine diagnostics.

Genomic evidence for the parallel evolution of coastal forms in the Senecio lautus complex

Instances of parallel ecotypic divergence where adaptation to similar conditions repeatedly cause similar phenotypic changes in closely related organisms are useful for studying the role of ecological selection in speciation. Here we used a combination of traditional and next generation genotyping techniques to test for the parallel divergence of plants from the Senecio lautus complex, a phenotypically variable groundsel that has adapted to disparate environments in the South Pacific. Phylogenetic analysis of a broad selection of Senecio species showed that members of the S. lautus complex form a distinct lineage that has diversified recently in Australasia. An inspection of thousands of polymorphisms in the genome of 27 natural populations from the S. lautus complex in Australia revealed a signal of strong genetic structure independent of habitat and phenotype. Additionally, genetic differentiation between populations was correlated with the geographical distance separating them, and the genetic diversity of populations strongly depended on geographical location. Importantly, coastal forms appeared in several independent phylogenetic clades, a pattern that is consistent with the parallel evolution of these forms. Analyses of the patterns of genomic differentiation between populations further revealed that adjacent populations displayed greater genomic heterogeneity than allopatric populations and are differentiated according to variation in soil composition. These results are consistent with a process of parallel ecotypic divergence in face of gene flow.

Effect of pretreatment on saccharification of sugarcane bagasse by complex and simple enzyme mixtures

Saccharification of sugarcane bagasse pretreated at the pilot-scale with different processes (in combination with steam-explosion) was evaluated. Maximum glucan conversion with Celluclast 1.5 L (15–25 FPU/g glucan) was in the following order: glycerol/HCl > HCl > H2SO4 > NaOH, with the glycerol system achieving ∼100% conversion. Surprisingly, the NaOH substrate achieved optimum saccharification with only 8 FPU/g glucan. Glucan conversions (3.6–6%) obtained with mixtures of endo-1,4-β-glucanase (EG) and β-glucosidase (βG) for the NaOH substrate were 2–6 times that of acid substrates. However, glucan conversions (15–60%) obtained with mixtures of cellobiohydrolase (CBH I) and βG on acidified glycerol substrate were 10–30% higher than those obtained for NaOH and acid substrates. The susceptibility of the substrates to enzymatic saccharification was explained by their physical and chemical attributes. Acidified glycerol pretreatment offers the opportunity to simplify the complexity of enzyme mixtures required for saccharification of lignocellulosics.

Mating compatibility among four pest members of the Bactrocera dorsalis fruit fly species complex (Diptera : Tephritidae)

Bactrocera dorsalis (Hendel), Bactrocera papayae Drew & Hancock, Bactrocera philippinensis Drew & Hancock, and Bactrocera carambolae Drew & Hancock are pest members within the B. dorsalis species complex of tropical fruit flies. The species status of these taxa is unclear and this confounds quarantine, pest management, and general research. Mating studies carried out under uniform experimental conditions are required as part of resolving their species limits. These four taxa were collected from the wild and established as laboratory cultures for which we subsequently determined levels of prezygotic compatibility, assessed by field cage mating trials for all pair-wise combinations. We demonstrate random mating among all pair-wise combinations involving B. dorsalis, B. papayae, and B. philippinensis. B. carambolae was relatively incompatible with each of these species as evidenced by nonrandom mating for all crosses. Reasons for incompatibility involving B. carambolae remain unclear; however, we observed differences in the location of couples in the field cage for some comparisons. Alongside other factors such as pheromone composition or other courtship signals, this may lead to reduced interspecific mating compatibility with B. carambolae. These data add to evidence that B. dorsalis, B. papayae, and B. philippinensis represent the same biological species, while B. carambolae remains sufficiently different to maintain its current taxonomic identity. This poses significant implications for this group's systematics, impacting on pest management, and international trade.

Multi-gene phylogenetic analysis of south-east Asian pest members of the Bactrocera dorsalis species complex (Diptera: Tephritidae) does not support current taxonomy

Bactrocera dorsalis sensu stricto, B. papayae, B. philippinensis and B. carambolae are serious pest fruit fly species of the B. dorsalis complex that predominantly occur in south-east Asia and the Pacific. Identifying molecular diagnostics has proven problematic for these four taxa, a situation that cofounds biosecurity and quarantine efforts and which may be the result of at least some of these taxa representing the same biological species. We therefore conducted a phylogenetic study of these four species (and closely related outgroup taxa) based on the individuals collected from a wide geographic range; sequencing six loci (cox1, nad4-3′, CAD, period, ITS1, ITS2) for approximately 20 individuals from each of 16 sample sites. Data were analysed within maximum likelihood and Bayesian phylogenetic frameworks for individual loci and concatenated data sets for which we applied multiple monophyly and species delimitation tests. Species monophyly was measured by clade support, posterior probability or bootstrap resampling for Bayesian and likelihood analyses respectively, Rosenberg's reciprocal monophyly measure, P(AB), Rodrigo's (P(RD)) and the genealogical sorting index, gsi. We specifically tested whether there was phylogenetic support for the four 'ingroup' pest species using a data set of multiple individuals sampled from a number of populations. Based on our combined data set, Bactrocera carambolae emerges as a distinct monophyletic clade, whereas B. dorsalis s.s., B. papayae and B. philippinensis are unresolved. These data add to the growing body of evidence that B. dorsalis s.s., B. papayae and B. philippinensis are the same biological species, which poses consequences for quarantine, trade and pest management.

Graphyne and graphdiyne : versatile catalysts for dehydrogenation of light metal complex hydrides

The interaction between new two-dimensional carbon allotropes, i.e. graphyne (GP) and graphdiyne (GD), and light metal complex hydrides LiAlH4, LiBH4, and NaAlH4 was studied using density functional theory (DFT) incorporating long range van der Waals dispersion correction. The light metal complex hydrides show much stronger interaction with GP and GP than that with fullerene due to the well defined pore structure. Such strong interactions greatly affect the degree of charge donation from the alkali metal atom to AlH4 or BH4, consequently destabilizing the Al-H or B-H bonds. Compared to the isolated light metal complex hydride, the presence of GP or GD can lead to a significant reduction of the hydrogen removal energy. Most interestingly, the hydrogen removal energies for LiBHx on GP and with GD are found to be lowered at all the stages (x from 4 to 1) whereas the H-removal energy in the third stage is increased for LiBH4 on fullerene. In addition, the presence of uniformly distributed pores on GP and GD is expected to facilitate the dehydrogenation of light metal complex hydrides. The present results highlight new interesting materials to catalyze light metal complex hydrides for potential application as media for hydrogen storage. Since GD has been successfully synthesized in a recent experiment, we hope the present work will stimulate further experimental investigations in this direction.

Guanxi as complex adaptive system : definition, description and underlying principles

Guanxi has become a common term in the wider business community and has attracted an increasing attention of researchers. However, a consistent understanding of the concept continues to be elusive. We critically review the extant guanxi literature to identify the major inconsistencies in the way guanxi is currently conceptualized and develop a conceptualization of guanxi which views guanxi as a complex adaptive system formed by the strategic establishing, evolving, utilizing, and maintaining of personal relationships based upon social norms of trust and reciprocal obligation unique to the Chinese culture. This study contributes to research of guanxi and to the field of Chinese management in several ways. First, we identify four levels of inconsistency surrounding the conceptualization of guanxi in the literature, thus clarifying the current common sources of confusion. Second, this study deconstructs the level and core values of guanxi to provide a more transparent picture, enabling researchers to develop more robust measures of guanxi. Finally, we made progress towards a more comprehensive understanding of guanxi by introducing the complex adaptive system perspective into the guanxi research.

Ageing, technology anxiety and intuitive use of complex interfaces

This paper presents the outcome of a study that investigated the relationships between technology prior experience, self-efficacy, technology anxiety, complexity of interface (nested versus flat) and intuitive use in older people. The findings show that, as expected, older people took less time to complete the task on the interface that used a flat structure when compared to the interface that used a complex nested structure. All age groups also used the flat interface more intuitively. However, contrary to what was hypothesised, older age groups did better under anxious conditions. Interestingly, older participants did not make significantly more errors compared with younger age groups on either interface structures.

Complex cognitive interactions in a badly designed world : Investigating the underlying causes of collisions between distinct road users

Collisions between distinct road users (e.g. drivers and riders, drivers and cyclists) make a substantial contribution to the road trauma burden. Although evidence suggests different road users interpret the same road situations contrarily, it is not clear how their situation awareness differs, nor is it clear which differences might lead to conflicts. This article presents the findings from an on-road study which was conducted to examine driver, cyclist and motorcyclist situation awareness in different road environments. The findings suggest that drivers, motorcyclists, and cyclists develop markedly different situational understandings even when operating in the same road environments. Examination of these differences indicate that they are likely to be compatible along arterial roads, shopping strips and at roundabouts, but that they may create conflicts between the different road users at intersections. The key role of road design in supporting compatible situation awareness and behaviour across different road users is discussed.

Genetic susceptibility to complex traits : moving towards informed analysis of whole-genome screens

Susceptibility to complex traits, by definition, involves aetiological polymorphisms at multiple genetic loci combined with variable contributions by environmental factors. However, the approaches taken to identifying genetic loci implicated in susceptibility to complex traits frequently overlooks the compounding contribution of multiple loci in favour of highlighting a single gene solely responsible for predisposition. It is only in a small minority of cases that this has resulted in clear disease heritability associated with polymorphisms in a single gene. More often, this approach has led to an accumulation of single-gene associations with minor contributions to disease susceptibility. As the genomic era advances and genome-wide screens become higher in resolution and throughput, the need for simultaneous consideration of multiple loci is becoming more important. With special reference to non-Hodgkin’s lymphoma (NHL), this chapter will overview the current progress made in elucidating genetic polymorphisms associated with disease susceptibility. We also present novel data from a high-resolution single nucleotide polymorphism (SNP) microarray screen for susceptibility loci that are involved in NHL. Using an ‘informed approach’, the findings are highlighted within the context of cellular pathways, and provide insight and new ideas for methods of analysis for genome-wide screens for susceptibility.

Passive control of a biventricular assist device with compliant inflow cannulae

Rotary ventricular assist device (VAD) support of the cardiovascular system is susceptible to suction events due to the limited preload sensitivity of these devices. This may be of particular concern with rotary biventricular support (BiVAD) where the native, flow-balancing Starling response is diminished in both ventricles. The reliability of sensor and sensor-less based control systems which aim to control VAD flow based on preload have limitations and thus an alternative solution is desired. This study introduces a compliant inflow cannula (CIC) which could improve the preload sensitivity of a rotary VAD by passively altering VAD flow depending on preload. To evaluate the design, both the CIC and a standard rigid inflow cannula were inserted into a mock circulation loop to enable biventricular heart failure support using configurations of atrial and ventricular inflow, and arterial outflow cannulation. A range of left (LVAD) and right VAD (RVAD) rotational speeds were tested as well as step changes in systemic/pulmonary vascular resistance to alter relative preloads, with resulting flow rates recorded. Simulated suction events were observed, particularly at higher VAD speeds, during support with the rigid inflow cannula, while the CIC prevented suction events under all circumstances. The compliant section passively restricted its internal diameter as preload was reduced, which increased the VAD circuit resistance and thus reduced VAD flow. Therefore, a compliant inflow cannula could potentially be used as a passive control system to prevent suction events in rotary left, right and biventricular support.

Evaluation of inflow cannulation site for implantation of right-sided rotary ventricular assist device

Right heart dysfunction is one of the most serious complications following implantation of a left ventricular assist device (LVAD), often leading to the requirement for short or long term right ventricular support (RVAD). The inflow cannulation site induces major haemodynamic changes and so there is a need to optimize the site used depending on the patient's condition. Therefore, this study evaluated and compared the haemodynamic influence of right atrial (RAC) and right ventricular (RVC) inflow cannulation sites. An in-vitro, variable heart failure, mock circulation loop was used to compare RAC and RVC in mild and severe biventricular heart failure (BHF) conditions. In the severe BHF condition, higher ventricular ejection fraction (RAC: 13.6%, RVC: 32.7%) and thus improved heart chamber and RVAD washout was observed with RVC, which suggested this strategy might be preferable for long term support (ie. bridge to transplant or destination therapy) to reduce the risk of thrombus formation. In the mild BHF condition, higher pulmonary valve flow (RAC: 3.33 L/min, RVC: 1.97 L/min) and lower right ventricular stroke work (RAC: 0.10 W, RVC: 0.13 W) and volumes were recorded with RAC. These results indicate an improved potential for myocardial recovery, thus RAC should be chosen in this condition. This in-vitro study suggests that RVAD inflow cannulation site should be chosen on a patient-specific basis with a view to the support strategy to promote myocardial recovery or reduce the risk of long-term complications.

Method for the production of porous complex metal oxides using a porogen

A method of producing porous complex oxides includes the steps of providing a mixt. of (a) precursor elements suitable to produce the complex oxide, or (b) one or more precursor elements suitable to produce particles of the complex oxide and one or more metal oxide particles; and (c) a particulate carbon-contg. pore-forming material selected to provide pore sizes in the range of 7-250 nm, and treating the mixt. to (i) form the porous complex oxide in which two or more of the precursor elements from (a) above or one or more of the precursor elements and one or more of the metals in the metal oxide particles from (b) above are incorporated into a phase of the complex metal oxide and the complex metal oxide has grain sizes in the range of 1-150 nm, and (ii) removing the pore-forming material under conditions such that the porous structure and compn. of the complex oxide is substantially preserved. The method may be used to produce nonrefractory metal oxides as well. The mixt. further includes a surfactant, or a polymer. [on SciFinder(R)]

Complex Modelling in the Primary and Middle School Years : An Interdisciplinary Approach

The world’s increasing complexity, competitiveness, interconnectivity, and dependence on technology generate new challenges for nations and individuals that cannot be met by continuing education as usual. With the proliferation of complex systems have come new technologies for communication, collaboration, and conceptualisation. These technologies have led to signifi cant changes in the forms of mathematical and scientifi c thinking required beyond the classroom. Modelling, in its various forms, can develop and broaden students’ mathematical and scientific thinking beyond the standard curriculum. This chapter first considers future competencies in the mathematical sciences within an increasingly complex world. Consideration is then given to interdisciplinary problem solving and models and modelling, as one means of addressing these competencies. Illustrative case studies involving complex, interdisciplinary modelling activities in Years 1 and 7 are presented.