Impact of exercise selection on hamstring muscle activation

Objective: To determine the extent to which different strength training exercises selectively activate the commonly injured biceps femoris long head (BFLH) muscle. Methods: This two-part observational study recruited 24 recreationally active males. Part 1 explored the amplitudes and the ratios of lateral to medial hamstring (BF/MH) normalised electromyography (nEMG) during the concentric and eccentric phases of 10 common strength training exercises. Part 2 used functional magnetic resonance imaging (fMRI) to determine the spatial patterns of hamstring activation during two exercises which i) most selectively, and ii) least selectively activated the BF in part 1. Results: Eccentrically, the largest BF/MH nEMG ratio was observed in the 45° hip extension exercise and the lowest was observed in the Nordic hamstring (NHE) and bent-knee bridge exercises. Concentrically, the highest BF/MH nEMG ratio was observed during the lunge and 45° hip extension and the lowest was observed for the leg curl and bent-knee bridge. fMRI revealed a greater BFLH to semitendinosus activation ratio in the 45° hip extension than the NHE (p<0.001). The T2 increase after hip extension for BFLH, semitendinosus and semimembranosus muscles were greater than that for BFSH (p<0.001). During the NHE, the T2 increase was greater for the semitendinosus than for the other hamstrings (p≤0.002). Conclusion: This investigation highlights the non-uniformity of hamstring activation patterns in different tasks and suggests that hip extension exercise more selectively activates the BFLH while the NHE preferentially recruits the semitendinosus. These findings have implications for strength training interventions aimed at preventing hamstring injury.

Patient-Generated Subjective Global Assessment Short Form (PG-SGA SF) is a valid screening tool in chemotherapy outpatients

Purpose In the oncology population where malnutrition prevalence is high, more descriptive screening tools can provide further information to assist triaging and capture acute change. The Patient-Generated Subjective Global Assessment Short Form (PG-SGA SF) is a component of a nutritional assessment tool which could be used for descriptive nutrition screening. The purpose of this study was to conduct a secondary analysis of nutrition screening and assessment data to identify the most relevant information contributing to the PG-SGA SF to identify malnutrition risk with high sensitivity and specificity. Methods This was an observational, cross-sectional study of 300 consecutive adult patients receiving ambulatory anti-cancer treatment at an Australian tertiary hospital. Anthropometric and patient descriptive data were collected. The scored PG-SGA generated a score for nutritional risk (PG-SGA SF) and a global rating for nutrition status. Receiver operating characteristic curves (ROC) were generated to determine optimal cut-off scores for combinations of the PG-SGA SF boxes with the greatest sensitivity and specificity for predicting malnutrition according to scored PG-SGA global rating. Results The additive scores of boxes 1–3 had the highest sensitivity (90.2 %) while maintaining satisfactory specificity (67.5 %) and demonstrating high diagnostic value (AUC = 0.85, 95 % CI = 0.81–0.89). The inclusion of box 4 (PG-SGA SF) did not add further value as a screening tool (AUC = 0.85, 95 % CI = 0.80–0.89; sensitivity 80.4 %; specificity 72.3 %). Conclusions The validity of the PG-SGA SF in chemotherapy outpatients was confirmed. The present study however demonstrated that the functional capacity question (box 4) does not improve the overall discriminatory value of the PG-SGA SF.

Instagrammatics and digital methods: Studying visual social media, from selfies and GIFs to memes and emoji

Visual content is a critical component of everyday social media, on platforms explicitly framed around the visual (Instagram and Vine), on those offering a mix of text and images in myriad forms (Facebook, Twitter, and Tumblr), and in apps and profiles where visual presentation and provision of information are important considerations. However, despite being so prominent in forms such as selfies, looping media, infographics, memes, online videos, and more, sociocultural research into the visual as a central component of online communication has lagged behind the analysis of popular, predominantly text-driven social media. This paper underlines the increasing importance of visual elements to digital, social, and mobile media within everyday life, addressing the significant research gap in methods for tracking, analysing, and understanding visual social media as both image-based and intertextual content. In this paper, we build on our previous methodological considerations of Instagram in isolation to examine further questions, challenges, and benefits of studying visual social media more broadly, including methodological and ethical considerations. Our discussion is intended as a rallying cry and provocation for further research into visual (and textual and mixed) social media content, practices, and cultures, mindful of both the specificities of each form, but also, and importantly, the ongoing dialogues and interrelations between them as communication forms.

On the behaviour of some physical parameterization methods in high-resolution numerical weather prediction models

Modern-day weather forecasting is highly dependent on Numerical Weather Prediction (NWP) models as the main data source. The evolving state of the atmosphere with time can be numerically predicted by solving a set of hydrodynamic equations, if the initial state is known. However, such a modelling approach always contains approximations that by and large depend on the purpose of use and resolution of the models. Present-day NWP systems operate with horizontal model resolutions in the range from about 40 km to 10 km. Recently, the aim has been to reach operationally to scales of 1 4 km. This requires less approximations in the model equations, more complex treatment of physical processes and, furthermore, more computing power. This thesis concentrates on the physical parameterization methods used in high-resolution NWP models. The main emphasis is on the validation of the grid-size-dependent convection parameterization in the High Resolution Limited Area Model (HIRLAM) and on a comprehensive intercomparison of radiative-flux parameterizations. In addition, the problems related to wind prediction near the coastline are addressed with high-resolution meso-scale models. The grid-size-dependent convection parameterization is clearly beneficial for NWP models operating with a dense grid. Results show that the current convection scheme in HIRLAM is still applicable down to a 5.6 km grid size. However, with further improved model resolution, the tendency of the model to overestimate strong precipitation intensities increases in all the experiment runs. For the clear-sky longwave radiation parameterization, schemes used in NWP-models provide much better results in comparison with simple empirical schemes. On the other hand, for the shortwave part of the spectrum, the empirical schemes are more competitive for producing fairly accurate surface fluxes. Overall, even the complex radiation parameterization schemes used in NWP-models seem to be slightly too transparent for both long- and shortwave radiation in clear-sky conditions. For cloudy conditions, simple cloud correction functions are tested. In case of longwave radiation, the empirical cloud correction methods provide rather accurate results, whereas for shortwave radiation the benefit is only marginal. Idealised high-resolution two-dimensional meso-scale model experiments suggest that the reason for the observed formation of the afternoon low level jet (LLJ) over the Gulf of Finland is an inertial oscillation mechanism, when the large-scale flow is from the south-east or west directions. The LLJ is further enhanced by the sea-breeze circulation. A three-dimensional HIRLAM experiment, with a 7.7 km grid size, is able to generate a similar LLJ flow structure as suggested by the 2D-experiments and observations. It is also pointed out that improved model resolution does not necessary lead to better wind forecasts in the statistical sense. In nested systems, the quality of the large-scale host model is really important, especially if the inner meso-scale model domain is small.

Primordial Isocurvature Perturbation in Light of CMB and LSS Data

The increased accuracy in the cosmological observations, especially in the measurements of the comic microwave background, allow us to study the primordial perturbations in grater detail. In this thesis, we allow the possibility for a correlated isocurvature perturbations alongside the usual adiabatic perturbations. Thus far the simplest six parameter \Lambda CDM model has been able to accommodate all the observational data rather well. However, we find that the 3-year WMAP data and the 2006 Boomerang data favour a nonzero nonadiabatic contribution to the CMB angular power sprctrum. This is primordial isocurvature perturbation that is positively correlated with the primordial curvature perturbation. Compared with the adiabatic \Lambda CMD model we have four additional parameters describing the increased complexity if the primordial perturbations. Our best-fit model has a 4% nonadiabatic contribution to the CMB temperature variance and the fit is improved by \Delta\chi^2 = 9.7. We can attribute this preference for isocurvature to a feature in the peak structure of the angular power spectrum, namely, the widths of the second and third acoustic peak. Along the way, we have improved our analysis methods by identifying some issues with the parametrisation of the primordial perturbation spectra and suggesting ways to handle these. Due to the improvements, the convergence of our Markov chains is improved. The change of parametrisation has an effect on the MCMC analysis because of the change in priors. We have checked our results against this and find only marginal differences between our parametrisation.

Author response: "Missed opportunity related to statistical methods"

"We thank MrGilder for his considered comments and suggestions for alternative analyses of our data. We also appreciate Mr Gilder’s support of our call for larger studies to contribute to the evidence base for preoperative loading with high-carbohydrate fluids..."

Evaluation of methods to estimate foliage density in the understorey of a tropical evergreen forest

Foliage density and leaf area index are important vegetation structure variables. They can be measured by several methods but few have been tested in tropical forests which have high structural heterogeneity. In this study, foliage density estimates by two indirect methods, the point quadrat and photographic methods, were compared with those obtained by direct leaf counts in the understorey of a wet evergreen forest in southern India. The point quadrat method has a tendency to overestimate, whereas the photographic method consistently and ignificantly underestimates foliage density. There was stratification within the understorey, with areas close to the ground having higher foliage densities.

Characterisation of cellulose- and lignin-based materials using x-ray scattering methods

Wood is an important material for the construction and pulping industries. Using x-ray diffraction the microfibril angle of Sitka spruce wood was studied in the first part of this thesis. Sitka spruce (Picea sitchensis [Bong.] Carr.) is native to the west coast of North America, but due to its fast growth rate, it has also been imported to Europe. So far, its nanometre scale properties have not been systematically characterised. In this thesis the microfibril angle of Sitka spruce was shown to depend significantly on the origin of the tree in the first annual rings near the pith. Wood can be further processed to separate lignin from cellulose and hemicelluloses. Solid cellulose can act as a reducer for metal ions and it is also a porous support for nanoparticles. By chemically reducing nickel or copper in the solid cellulose support it is possible to get small nanoparticles on the surfaces of the cellulose fibres. Cellulose supported metal nanoparticles can potentially be used as environmentally friendly catalysts in organic chemistry reactions. In this thesis the size of the nickel and copper containing nanoparticles were studied using anomalous small-angle x-ray scattering and wide-angle x-ray scattering. The anomalous small-angle x-ray scattering experiments showed that the crystallite size of the copper oxide nanoparticles was the same as the size of the nanoparticles, so the nanoparticles were single crystals. The nickel containing nanoparticles were amorphous, but crystallised upon heating. The size of the nanoparticles was observed to be smaller when the reduction of nickel was done in aqueous ammonium hydrate medium compared to reduction made in aqueous solution. Lignin is typically seen as the side-product of wood industries. Lignin is the second most abundant natural polymer on Earth, and it possesses potential to be a useful material for many purposes in addition to being an energy source for the pulp mills. In this thesis, the morphology of several lignins, which were produced by different separation methods from wood, was studied using small-angle and ultra small-angle x-ray scattering. It was shown that the fractal model previously proposed for the lignin structure does not apply to most of the extracted lignin types. The only lignin to which the fractal model could be applied was kraft lignin. In aqueous solutions the average shape of the low molar mass kraft lignin particles was observed to be elongated and flat. The average shape does not necessarily correspond to the shape of the individual particles because of the polydispersity of the fraction and due to selfassociation of the particles. Lignins, and especially lignosulfonate, have many uses as dispersants, binders and emulsion stabilisers. In this thesis work the selfassociation of low molar mass lignosulfonate macromolecules was observed using small-angle x-ray scattering. By taking into account the polydispersity of the studied lignosulfonate fraction, the shape of the lignosulfonate particles was determined to be flat by fitting an oblate ellipsoidal model to the scattering intensity.

Conformal Field Theory Methods for Variants of Schramm-Loewner Evolutions

This thesis consists of an introduction, four research articles and an appendix. The thesis studies relations between two different approaches to continuum limit of models of two dimensional statistical mechanics at criticality. The approach of conformal field theory (CFT) could be thought of as the algebraic classification of some basic objects in these models. It has been succesfully used by physicists since 1980's. The other approach, Schramm-Loewner evolutions (SLEs), is a recently introduced set of mathematical methods to study random curves or interfaces occurring in the continuum limit of the models. The first and second included articles argue on basis of statistical mechanics what would be a plausible relation between SLEs and conformal field theory. The first article studies multiple SLEs, several random curves simultaneously in a domain. The proposed definition is compatible with a natural commutation requirement suggested by Dubédat. The curves of multiple SLE may form different topological configurations, ``pure geometries''. We conjecture a relation between the topological configurations and CFT concepts of conformal blocks and operator product expansions. Example applications of multiple SLEs include crossing probabilities for percolation and Ising model. The second article studies SLE variants that represent models with boundary conditions implemented by primary fields. The most well known of these, SLE(kappa, rho), is shown to be simple in terms of the Coulomb gas formalism of CFT. In the third article the space of local martingales for variants of SLE is shown to carry a representation of Virasoro algebra. Finding this structure is guided by the relation of SLEs and CFTs in general, but the result is established in a straightforward fashion. This article, too, emphasizes multiple SLEs and proposes a possible way of treating pure geometries in terms of Coulomb gas. The fourth article states results of applications of the Virasoro structure to the open questions of SLE reversibility and duality. Proofs of the stated results are provided in the appendix. The objective is an indirect computation of certain polynomial expected values. Provided that these expected values exist, in generic cases they are shown to possess the desired properties, thus giving support for both reversibility and duality.

Studies on the ionic transport and structural investigations of La0.5Li0.5TiO3 perovskite synthesized by wet chemical methods and the effect of Ce, Zr substitution at Ti site

La0.5Li0.5TiO3 perovskite was synthesized by various wet chemical methods. By adopting low temperature methods of preparation lithium loss from the material is prevented. La0.5Li0.5TiO3 (LLTO) was formed with cubic symmetry at 1473 K. LLTO was formed at relatively lower temperature by using hydrothermal preparation method. PVA gel-decomposition route yield tetragonal LLTO on annealing the dried gel at 1473 K. By using gel-carbonate route LiTi2O4 minor phase was found to remain even after heat-treatment at 1473 K. The hydroxylation of LLTO was done in deionized water as well as in dilute acetic acid medium. By hydroxylation process incorporation of hydroxyls and leaching out of Li+ was observed from the material. The Li+ concentration of these compositions was examined by AAS. The electrical conductivities of these compositions were measured by dc and ac impedance techniques at elevated temperatures. The activation energies of electrical conduction for these compositions were estimated from the experimental results. The measured activation energy of Li+ conduction is 0.34 eV. Unhydroxylated samples exhibit only Li+ conduction, whereas, the hydroxylated LLTO show proton conductivity at 298-550 K in addition to Li+ conductivity. The effect of Zr or Ce substitution in place of Ti were attempted. La0.5Li0.5ZrO3 Perovskite was not formed; instead pyrochlore phase (La2Zr2O7) along with monoclinic ZrO2 phases was observed above 1173 K; below 1173 K cubic ZrO2 is stable. (La0.5Li0.5)(2)CeO4 solid solution was formed in the case of Ce substitution at Ti sublattice on heat-treatment up to 1673 K. (c) 2005 Springer Science + Business Media, Inc.

Approximate methods for step function response of undamped non-linear spring mass systems with arbitrary hardening type spring characteristic

The possibility of applying two approximate methods for determining the salient features of response of undamped non-linear spring mass systems subjected to a step input, is examined. The results obtained on the basis of these approximate methods are compared with the exact results that are available for some particular types of spring characteristics. The extension of the approximate methods for non-linear systems with general polynomial restoring force characteristics is indicated.