Does whole body vibration have clinically significant neurophysiological and neurovascular implications?

Whole body vibration has received much attention as an innovative approach to exercise, leading to constantly increasing attention fro m the scientific community. Previous research considering occupational vibration has illustrated the risks associated with high levels of exposure to vibration; however during vibration exercise the exposure duration is much shorter and therefore the potential complications must be reconsidered. This review brings together research from various aspects of occupational vibration, clinical research and vibration exercise to address issues within the context of health and safety with a particular focus on neurophysiological and neurovascular responses. The results indicate that peripheral nerve and blood vessels are exposed to risks such as compression, shear stress and altered function as a response to vibration. However, correct planning and implementation of exercise protocols should effectively control these risks. By summarising the areas that have received attention an overview of potential complications will be achieved; with an understanding of which factors prevent participation and those that simply require an amended approach to vibration exercise

Collapsing molecular clouds with tracer particles: Part II, Collapse Histories

In order to develop a complete theory of star formation, one essentially needs to know two things: what collapses, and how long it takes. This is the second paper in a series, where we query how long a parcel of gas takes to collapse and the process it undergoes. We embed pseudo-Lagrangian tracer particles in simulations of collapsing molecular clouds, identify the particles that end in dense knots, and then examine the collapse history of the gas. We find a nearly universal behavior of cruise-then-collapse. We identify gas the moment before it collapses, $t_{\rm{sing}}$, and examine how it transitions to high density. We find that the time to collapse is uniformly distributed between $0.25 t_{\rm{ff}}$ and the end of the simulation at $\sim 1 t_{\rm{ff}}$, and that the collapse duration is universally short, $\Delta t \sim 0.1 t_{\rm{ff}}$. We find that the collapse of each core happens by a process akin to violent relaxation, wherein a fast reordering of the potential and kinetic energies occurs, in $0.1 t_{\rm{ff}}$, after which a virialized object remains. We describe the collapse in four stages; collection, hardening, singularity, and mosh. Collection sweeps low density gas into moderate density. Hardening brings kinetic and gravitational energies into quasi-equipartition. Singularity is the free-fall collapse, forming a virialized object in $\sim 0.1 t_{\rm{ff}}$. Mosh encompasses tidal dynamics of sub clumps and nearby cores during the collapse. In this work we focus primarily on isolated clumps. With this novel lens we can observe the details of collapse

OntoDas – a tool for facilitating the construction of complex queries to the Gene Ontology

<p>Abstract</p> <p>Background</p> <p>Ontologies such as the Gene Ontology can enable the construction of complex queries over biological information in a conceptual way, however existing systems to do this are too technical. Within the biological domain there is an increasing need for software that facilitates the flexible retrieval of information. OntoDas aims to fulfil this need by allowing the definition of queries by selecting valid ontology terms.</p> <p>Results</p> <p>OntoDas is a web-based tool that uses information visualisation techniques to provide an intuitive, interactive environment for constructing ontology-based queries against the Gene Ontology Database. Both a comprehensive use case and the interface itself were designed in a participatory manner by working with biologists to ensure that the interface matches the way biologists work. OntoDas was further tested with a separate group of biologists and refined based on their suggestions.</p> <p>Conclusion</p> <p>OntoDas provides a visual and intuitive means for constructing complex queries against the Gene Ontology. It was designed with the participation of biologists and compares favourably with similar tools. It is available at <url>http://ontodas.nbn.ac.za</url></p

Image similarity metrics suitable for infrared video stabilization during active wildfire monitoring : a comparative analysis

Aerial Thermal Infrared (TIR) imagery has demonstrated tremendous potential to monitor active forest fires and acquire detailed information about fire behavior. However, aerial video is usually unstable and requires inter-frame registration before further processing. Measurement of image misalignment is an essential operation for video stabilization. Misalignment can usually be estimated through image similarity, although image similarity metrics are also sensitive to other factors such as changes in the scene and lighting conditions. Therefore, this article presents a thorough analysis of image similarity measurement techniques useful for inter-frame registration in wildfire thermal video. Image similarity metrics most commonly and successfully employed in other fields were surveyed, adapted, benchmarked and compared. We investigated their response to different camera movement components as well as recording frequency and natural variations in fire, background and ambient conditions. The study was conducted in real video from six fire experimental scenarios, ranging from laboratory tests to large-scale controlled burns. Both Global and Local Sensitivity Analyses (GSA and LSA, respectively) were performed using state-of-the-art techniques. Based on the obtained results, two different similarity metrics are proposed to satisfy two different needs. A normalized version of Mutual Information is recommended as cost function during registration, whereas 2D correlation performed the best as quality control metric after registration. These results provide a sound basis for image alignment measurement and open the door to further developments in image registration, motion estimation and video stabilization for aerial monitoring of active wildland fires

The age-redshift relation for Luminous Red Galaxies in the Sloan Digital Sky Survey

We present a detailed analysis of 17,852 quiescent, Luminous Red Galaxies (LRGs) selected from Sloan Digital Sky Survey (SDSS) Data Release Seven (DR7) spanning a redshift range of 0.0 < z < 0.4. These galaxies are co-added into four equal bins of velocity dispersion and luminosity to produce high signal-to-noise spectra (>100A^{-1}), thus facilitating accurate measurements of the standard Lick absorption-line indices. In particular, we have carefully corrected and calibrated these indices onto the commonly used Lick/IDS system, thus allowing us to compare these data with other measurements in the literature, and derive realistic ages, metallicities ([Z/H]) and alpha-element abundance ratios ([alpha/Fe]) for these galaxies using Simple Stellar Population (SSP) models. We use these data to study the relationship of these galaxy parameters with redshift, and find little evidence for evolution in metallicity or alpha-elements (especially for our intermediate mass samples). This demonstrates that our subsamples are consistent with pure passive evolving (i.e. no chemical evolution) and represent a homogeneous population over this redshift range. We also present the age-redshift relation for these LRGs and clearly see a decrease in their age with redshift (5 Gyrs over the redshift range studied here) which is fully consistent with the cosmological lookback times in a concordance Lambda CDM universe. We also see that our most massive sample of LRGs is the youngest compared to the lower mass galaxies. We provide these data now to help future cosmological and galaxy evolution studies of LRGs, and provide in the appendices of this paper the required methodology and information to calibrate SDSS spectra onto the Lick/IDS system.Comment: 26 pages, with several appendices containing data. Accepted for publication in MNRA

The Contribution of Halos with Different Mass Ratios to the Overall Growth of Cluster-Sized Halos

We provide a new observational test for a key prediction of the \Lambda CDM cosmological model: the contributions of mergers with different halo-to-main-cluster mass ratios to cluster-sized halo growth. We perform this test by dynamically analyzing seven galaxy clusters, spanning the redshift range $0.13 < z_c < 0.45$ and caustic mass range $0.4-1.5$ $10^{15} h_{0.73}^{-1}$ M$_{\odot}$, with an average of 293 spectroscopically-confirmed bound galaxies to each cluster. The large radial coverage (a few virial radii), which covers the whole infall region, with a high number of spectroscopically identified galaxies enables this new study. For each cluster, we identify bound galaxies. Out of these galaxies, we identify infalling and accreted halos and estimate their masses and their dynamical states. Using the estimated masses, we derive the contribution of different mass ratios to cluster-sized halo growth. For mass ratios between ~0.2 and ~0.7, we find a ~1 $\sigma$ agreement with \Lambda CDM expectations based on the Millennium simulations I and II. At low mass ratios, $\lesssim 0.2$, our derived contribution is underestimated since the detection efficiency decreases at low masses, $\sim 2 \times 10^{14}$ $h_{0.73}^{-1}$ M$_{\odot}$. At large mass ratios, $\gtrsim 0.7$, we do not detect halos probably because our sample, which was chosen to be quite X-ray relaxed, is biased against large mass ratios. Therefore, at large mass ratios, the derived contribution is also underestimated.Comment: 25 pages, 16 figures, 6 tables, 2 machine readable tables, accepted for publication in ApJ, updated acknowledgements and data table format modifications mad

Viral and Cellular factors leading to the Loss of CD4 Homeostasis in HIV-1 Viremic Nonprogressors

Human immunodeficiency virus type 1 (HIV-1) viremic nonprogressors (VNPs) represent a very rare HIV-1 extreme phenotype. VNPs are characterized by persistent high plasma viremia and maintenance of CD41 T-cell counts in the absence of treatment. However, the causes of nonpathogenic HIV-1 infection in VNPs remain elusive. Here, we identified for the first time two VNPs who experienced the loss of CD41 homeostasis (LoH) after more than 13 years. We characterized in deep detail viral and host factors associated with the LoH and compared with standard VNPs and healthy controls. The viral factors determined included HIV-1 coreceptor usage and replicative capacity. Changes in CD41 and CD81 T-cell activation, maturational phenotype, and expression of CCR5 and CXCR6 in CD41 T-cells were also evaluated as host-related factors. Consistently, we determined a switch in HIV-1 coreceptor use to CXCR4 concomitant with an increase in replicative capacity at the LoH for the two VNPs. Moreover, we delineated an increase in the frequency of HLA-DR1CD381 CD41 and CD81 T cells and traced the augment of naive T-cells upon polyclonal activation with LoH. Remarkably, very low and stable levels of CCR5 and CXCR6 expression in CD41 T-cells were measured over time. Overall, our results demonstrated HIV-1 evolution toward highly pathogenic CXCR4 strains in the context of very limited and stable expression of CCR5 and CXCR6 in CD41 T cells as potential drivers of LoH in VNPs. These data bring novel insights into the correlates of nonpathogenic HIV1 infection. Importance: The mechanism behind nonpathogenic human immunodeficiency virus type 1 (HIV-1) infection remains poorly understood, mainly because of the very low frequency of viremic nonprogressors (VNPs). Here, we report two cases of VNPs who experienced the loss of CD41 T-cell homeostasis (LoH) after more than 13 years of HIV-1 infection. The deep characterization of viral and host factors supports the contribution of viral and host factors to the LoH in VNPs. Thus, HIV-1 evolution toward highly replicative CXCR4 strains together with changes in T-cell activation and maturational phenotypes were found. Moreover, we measured very low and stable levels of CCR5 and CXCR6 in CD41 T-cells over time. These findings support viral evolution toward X4 strains limited by coreceptor expression to control HIV-1 pathogenesis and demonstrate the potential of host-dependent factors, yet to be fully elucidated in VNPs, to control HIV-1 pathogenesis.This research was supported by a Gilead Fellowship (grant GLD15/0298) and La Caixa Foundation (grant LCF/PR/PR16/11110026). M.C.-L. is a Beatriu de Pinós postdoctoral fellow (grant BP 00075) supported by the Government of Catalonia’s Secretariat for Universities and Research of the Ministry of Economy and Knowledge. J.G.P. was supported by the ISCIII (grant CP15/00014). E.J.-M. was funded by Redes Temáticas de Investigación en SIDA (ISCIII RETIC RD16/0025/0041); Acción Estratégica en Salud; Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2008–2011; and Instituto de Salud Carlos III. E.J.-M. was cofunded by European Regional Development Fund/European Social Fund (FEDER) “Investing in your future.” J.M.-P. is supported by the Spanish Ministry of Science and Innovation (grant PID2019-109870RB-I00). J.G.P. and M.C.-L. designed the study, supervised experiments and data. J.G.P., M.C.-L., and A.K. contributed to data interpretation. M.C.-L., R.P., E.J.-M., M.P., and C.C. performed experiments, analyzed, and interpreted the data. J.D. carried out the clinical follow-up and patient identification. M.C.-L., D.O., M.P., and C.C. performed data analysis. M.C.-L., A.K., M.P., C.L.-G., B.C., J.M.-P., and J.G.P. performed manuscript writing, critical revision, and discussion. We declare no conflict of interest.S

CLASH: Mass Distribution in and around MACS J1206.2-0847 from a Full Cluster Lensing Analysis

We derive an accurate mass distribution of the galaxy cluster MACS J1206.2-0847 (z=0.439) from a combined weak-lensing distortion, magnification, and strong-lensing analysis of wide-field Subaru BVRIz' imaging and our recent 16-band Hubble Space Telescope observations taken as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) program. We find good agreement in the regions of overlap between several weak and strong lensing mass reconstructions using a wide variety of modeling methods, ensuring consistency. The Subaru data reveal the presence of a surrounding large scale structure with the major axis running approximately north-west south-east (NW-SE), aligned with the cluster and its brightest galaxy shapes, showing elongation with a \sim 2:1 axis ratio in the plane of the sky. Our full-lensing mass profile exhibits a shallow profile slope dln\Sigma/dlnR\sim -1 at cluster outskirts (R>1Mpc/h), whereas the mass distribution excluding the NW-SE excess regions steepens further out, well described by the Navarro-Frenk-White form. Assuming a spherical halo, we obtain a virial mass M_{vir}=(1.1\pm 0.2\pm 0.1)\times 10^{15} M_{sun}/h and a halo concentration c_{vir} = 6.9\pm 1.0\pm 1.2 (\sim 5.7 when the central 50kpc/h is excluded), which falls in the range 4 <7 of average c(M,z) predictions for relaxed clusters from recent Lambda cold dark matter simulations. Our full lensing results are found to be in agreement with X-ray mass measurements where the data overlap, and when combined with Chandra gas mass measurements, yield a cumulative gas mass fraction of 13.7^{+4.5}_{-3.0}% at 0.7Mpc/h (\approx 1.7r_{2500}), a typical value observed for high mass clusters.Comment: Accepted by ApJ (30 pages, 17 figures), one new figure (Figure 10) added, minor text changes; a version with high resolution figures available at http://www.asiaa.sinica.edu.tw/~keiichi/upfiles/MACS1206/ms_highreso.pd