304 research outputs found

    The effect of music on body sway when standing in a moving virtual environment

    Get PDF
    Movement of the visual environment presented through virtual reality (VR) has been shown to invoke postural adjustments measured by increased body sway. The effect of auditory information on body sway seems to be dependent on context with sounds such as white noise, tones, and music being used to amplify or suppress sway. This study aims to show that music manipulated to match VR motion further increases body sway. Twenty-eight subjects stood on a force plate and experienced combinations of 3 visual conditions (VR translation in the AP direction at 0.1 Hz, no translation, and eyes closed) and 4 music conditions (Mozart's Jupiter Symphony modified to scale volume at 0.1 Hz and 0.25 Hz, unmodified music, and no music) Body sway was assessed by measuring center of pressure (COP) velocities and RMS. Cross-coherence between the body sway and the 0.1 Hz and 0.25 Hz stimuli was also determined. VR translations at 0.1 Hz matched with 0.1Hz shifts in music volume did not lead to more body sway than observed in the no music and unmodified music conditions. Researchers and clinicians may consider manipulating sound to enhance VR induced body sway, but findings from this study would not suggest using volume to do so

    The Residual Method for Regularizing Ill-Posed Problems

    Get PDF
    Although the \emph{residual method}, or \emph{constrained regularization}, is frequently used in applications, a detailed study of its properties is still missing. This sharply contrasts the progress of the theory of Tikhonov regularization, where a series of new results for regularization in Banach spaces has been published in the recent years. The present paper intends to bridge the gap between the existing theories as far as possible. We develop a stability and convergence theory for the residual method in general topological spaces. In addition, we prove convergence rates in terms of (generalized) Bregman distances, which can also be applied to non-convex regularization functionals. We provide three examples that show the applicability of our theory. The first example is the regularized solution of linear operator equations on LpL^p-spaces, where we show that the results of Tikhonov regularization generalize unchanged to the residual method. As a second example, we consider the problem of density estimation from a finite number of sampling points, using the Wasserstein distance as a fidelity term and an entropy measure as regularization term. It is shown that the densities obtained in this way depend continuously on the location of the sampled points and that the underlying density can be recovered as the number of sampling points tends to infinity. Finally, we apply our theory to compressed sensing. Here, we show the well-posedness of the method and derive convergence rates both for convex and non-convex regularization under rather weak conditions.Comment: 29 pages, one figur

    Parameter identification problems in the modelling of cell motility

    Get PDF
    We present a novel parameter identification algorithm for the estimation of parameters in models of cell motility using imaging data of migrating cells. Two alternative formulations of the objective functional that measures the difference between the computed and observed data are proposed and the parameter identification problem is formulated as a minimisation problem of nonlinear least squares type. A Levenberg–Marquardt based optimisation method is applied to the solution of the minimisation problem and the details of the implementation are discussed. A number of numerical experiments are presented which illustrate the robustness of the algorithm to parameter identification in the presence of large deformations and noisy data and parameter identification in three dimensional models of cell motility. An application to experimental data is also presented in which we seek to identify parameters in a model for the monopolar growth of fission yeast cells using experimental imaging data. Our numerical tests allow us to compare the method with the two different formulations of the objective functional and we conclude that the results with both objective functionals seem to agree

    Malignant B Cells Induce the Conversion of CD4+CD25− T Cells to Regulatory T Cells in B-Cell Non-Hodgkin Lymphoma

    Get PDF
    Recent evidence has demonstrated that regulatory T cells (Treg) were enriched in the tumor sites of patients with B-cell non-Hodgkin lymphoma (NHL). However, the causes of enrichment and suppressive mechanisms need to be further elucidated. Here we demonstrated that CD4+CD25+FoxP3+CD127lo Treg were markedly increased and their phenotypes were different in peripheral blood (PB) as well as bone marrow (BM) from newly diagnosed patients with B-cell NHL compared with those from healthy volunteers (HVs). Involved lymphatic tissues also showed higher frequencies of Treg than benign lymph nodes. Moreover, the frequencies of Treg were significantly higher in involved lymphatic tissues than those from PB as well as BM in the same patients. Suppression mediated by CD4+CD25+ Treg co-cultured with allogeneic CFSE-labeled CD4+CD25− responder cells was also higher in involved lymphatic tissues from B-cell NHL than that mediated by Treg from HVs. In addition, we found that malignant B cells significantly induced FoxP3 expression and regulatory function in CD4+CD25− T cells in vitro. In contrast, normal B cells could not induce the conversion of CD4+CD25− T cells to Treg. We also showed that the PD-1/B7-H1 pathway might play an important role in Treg induction. Taken together, our results suggest that malignant B cells induce the conversion of CD4+CD25− T cells to Treg, which may play a role in the pathogenesis of B-cell NHL and represent a promising therapeutic target

    The Warnie volcanic province : Jurassic intraplate volcanism in Central Australia

    Get PDF
    We wish to thank Santos Ltd. for providing us with the Snowball 3D seismic survey. In particular we wish to thank Jenni Clifford and Lance Holmes who provided helpful feedback and 2D seismic lines covering the Lambda 1, Orientos 2 and Warnie East 1 wells. We also wish to thank Beach Energy, in particular Rob Menpes, for the helpful discussions and feedback on the manuscript in addition to helping us with the analysis of the magnetic data. The work contained in this paper contains work conducted during a PhD study undertaken as part of the Natural Environment Research Council (NERC) Centre for Doctoral Training (CDT) in Oil & Gas [grant number NEM00578X/1] and is fully funded by NERC whose support is gratefully acknowledged. Lastly, the two anonymous reviews of the manuscript are thanked for their insightful and constructive comments that significantly improved the work presented.Peer reviewedPostprin

    Complete Mitochondrial Genome Sequence of Three Tetrahymena Species Reveals Mutation Hot Spots and Accelerated Nonsynonymous Substitutions in Ymf Genes

    Get PDF
    The ciliate Tetrahymena, a model organism, contains divergent mitochondrial (Mt) genome with unusual properties, where half of its 44 genes still remain without a definitive function. These genes could be categorized into two major groups of KPC (known protein coding) and Ymf (genes without an identified function). To gain insights into the mechanisms underlying gene divergence and molecular evolution of Tetrahymena (T.) Mt genomes, we sequenced three Mt genomes of T.paravorax, T.pigmentosa, and T.malaccensis. These genomes were aligned and the analyses were carried out using several programs that calculate distance, nucleotide substitution (dn/ds), and their rate ratios (ω) on individual codon sites and via a sliding window approach. Comparative genomic analysis indicated a conserved putative transcription control sequence, a GC box, in a region where presumably transcription and replication initiate. We also found distinct features in Mt genome of T.paravorax despite similar genome organization among these ∼47 kb long linear genomes. Another significant finding was the presence of at least one or more highly variable regions in Ymf genes where majority of substitutions were concentrated. These regions were mutation hotspots where elevated distances and the dn/ds ratios were primarily due to an increase in the number of nonsynonymous substitutions, suggesting relaxed selective constraint. However, in a few Ymf genes, accelerated rates of nonsynonymous substitutions may be due to positive selection. Similarly, on protein level the majority of amino acid replacements occurred in these regions. Ymf genes comprise half of the genes in Tetrahymena Mt genomes, so understanding why they have not been assigned definitive functions is an important aspect of molecular evolution. Importantly, nucleotide substitution types and rates suggest possible reasons for not being able to find homologues for Ymf genes. Additionally, comparative genomic analysis of complete Mt genomes is essential in identifying biologically significant motifs such as control regions

    Association of physical exercise and calcium intake with bone mass measured by quantitative ultrasound

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Interventions other than medications in the management of osteoporosis are often overlooked. The purpose of this study was to investigate the association of physical activity and calcium intake with bone parameters.</p> <p>Methods</p> <p>We measured the heel T-score and stiffness index (SI) in 1890 pre- and postmenopausal women by quantitative ultrasound (QUS) and assessed physical activity and dietary calcium intake by questionnaire. Participants were divided according to their weekly physical activity (sedentary, moderately active, systematically active) and daily calcium consumption (greater than or less than 800 mg/day).</p> <p>Results</p> <p>SI values were significantly different among premenopausal groups (p = 0.016) and between sedentary and systematically active postmenopausal women (p = 0.039). QUS T-scores in systematically active premenopausal women with daily calcium intake > 800 mg/day were significantly higher than those in all other activity groups (p < 0.05) independent of calcium consumption.</p> <p>Conclusions</p> <p>Systematic physical activity and adequate dietary calcium intake are indicated for women as a means to maximize bone status benefits.</p
    corecore