5,565 research outputs found

    Thermal Analyses of the Los Angeles Smog Aerosol

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    It has been shown by earlier studies on the formation of the Los Angeles smog aerosol, that a significant fraction of the particulate matter in the visible size range is made by secondary gas-particle conversion processes, and that it consists mainly of liquid matter. In this study the volatility was studied quantitatively by heating the smog aerosol up to 250°C and simultaneously measuring the scattering coefficient using a nephelometer and the change of size distribution by an optical counter. The thermal analyses revealed that 50–80% of the submicron aerosol mass is volatile at 220°C. Inspection of the shapes of thermo-nephelograms (bscat vs temperature) also revealed that photochemically formed aerosols have distinctly different thermo-nephelograms than those obtained on humid “hazy” days. Thus it is suggested that thermal analyses may at least in some instances provide the means of on-line monitoring the origin of the ambient aerosol

    Blip glitches in Advanced LIGO data

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    Blip glitches are short noise transients present in data from ground-based gravitational-wave observatories. These glitches resemble the gravitational-wave signature of massive binary black hole mergers. Hence, the sensitivity of transient gravitational-wave searches to such high-mass systems and other potential short duration sources is degraded by the presence of blip glitches. The origin and rate of occurrence of this type of glitch have been largely unknown. In this paper we explore the population of blip glitches in Advanced LIGO during its first and second observing runs. On average, we find that Advanced LIGO data contains approximately two blip glitches per hour of data. We identify four subsets of blip glitches correlated with detector auxiliary or environmental sensor channels, however the physical causes of the majority of blips remain unclear

    Cerebrospinal Fluid Cytokines and Neurodegeneration-Associated Proteins in Parkinson's Disease.

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    INTRODUCTION: Immune markers are altered in Parkinson's disease (PD), but relationships between cerebrospinal fluid (CSF) and plasma cytokines and associations with neurodegeneration-associated proteins remain unclear. METHODS: CSF and plasma samples and demographic/clinical measures were obtained from 35 PD patients. CSF samples were analyzed for cytokines (together with plasma) and for α-synuclein, amyloid ÎČ(1-42) peptide, total tau, and phospho(Thr231)-tau. RESULTS: There were no CSF-plasma cytokine correlations. Interleukin (IL)-8 was higher and interferon-Îł, IL-10, and tumor necrosis factor-α were lower in CSF versus plasma. In CSF, total tau correlated positively with IL-8 and IL-1ÎČ, whereas α-synuclein correlated positively with amyloid ÎČ(1-42) and negatively with semantic fluency (a known marker of PD dementia risk). DISCUSSION: CSF and peripheral cytokine profiles in PD are not closely related. Associations between CSF IL-8 and IL-1ÎČ and tau suggest that CSF inflammatory changes may relate to tau pathology within PD. CSF α-synuclein/amyloid ÎČ may reflect the risk of developing PD dementia. © 2020 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.Funding for this work was provided by the Rosetrees Trust (M369-F1), Addenbrooke’s Charitable Trust (PF15/CWG) and the NIHR Cambridge Biomedical Research Centre Dementia and Neurodegeneration Theme (146281). RSW was supported by a Fellowship from Addenbrooke’s Charitable Trust (RG77199). SFM was supported by the Transeuro EU FP7 grant (242003) and is now an NIHR Academic Clinical Fellow (ACF-2015-23-501). DPB is supported by a Wellcome Trust Clinical Research Career Development Fellowship. RAB is an NIHR Senior Investigator (NF-SI-0616-10011) and is supported by the Wellcome Trust-MRC Cambridge Stem Cell Institute. CHWG holds a RCUK/UKRI Research Innovation Fellowship awarded by the Medical Research Council (MR/R007446/1) and receives support from the Cambridge Centre for Parkinson-Plus

    Densely sampled phylogenies frequently deviate from maximum parsimony in simple and local ways

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    Why do phylogenetic algorithms fail when they return incorrect answers? This simple question has not been answered in detail, even for maximum parsimony (MP), the simplest phylogenetic criterion. Understanding MP has recently gained relevance in the regime of extremely dense sampling, where each virus sample commonly differs by zero or one mutation from another previously sampled virus. Although recent research shows that evolutionary histories in this regime are close to being maximally parsimonious, the structure of their deviations from MP is not yet understood. In this paper, we develop algorithms to understand how the correct tree deviates from being MP in the densely sampled case. By applying these algorithms to simulations that realistically mimic the evolution of SARS-CoV-2, we find that simulated trees frequently only deviate from maximally parsimonious trees locally, through simple structures consisting of the same mutation appearing independently on sister branches.Comment: 18 pages, 7 figures, submitted to RECOMB 202

    Effects of Classroom-Based Resistance Training With and Without Cognitive Training on Adolescents’ Cognitive Function, On-task Behavior, and Muscular Fitness

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    Aim: Participation in classroom physical activity breaks may improve children’s cognition, but few studies have involved adolescents. The primary aim of this study was to examine the effects of classroom-based resistance training with and without cognitive training on adolescents’ cognitive function. Methods: Participants were 97 secondary school students (45.4% females, mean age 15.78 ± 0.44). Four-year 10 classes from one school were included in this four-arm cluster randomized controlled trial. Classes were randomly assigned to the following groups: sedentary control with no cognitive training, sedentary with cognitive training, resistance training without cognitive training, and resistance training with cognitive training. Sessions varied in levels of both cognitive demand and resistance training (i.e., high vs. low) and were administered three times per week for 4 weeks (12 sessions). Inhibition, cognitive flexibility, episodic memory, on-task behavior, and muscular fitness were assessed at baseline and post-test. Linear mixed models were used to examine changes within and between groups. Results: In comparison with the control group, episodic memory improved significantly in the resistance training without cognitive training group (−9.87 units, 95% CI: −17.71 to −2.03, p = 0.014, d = 0.72). There were no group-by-time effects for inhibition or cognitive flexibility. Classroom activity breaks both with and without cognitive demand improved participants’ on-task behavior in comparison with the control and sedentary group. The resistance training programs did not lead to improvements in muscular fitness. Conclusion: Participation in body weight resistance training without cognitive training led to selective improvements in episodic memory. No training effects were found for inhibition or cognitive flexibility. A longer study period may be necessary to induce improvements in muscular fitness and associated changes in inhibition and cognitive flexibilit

    Diffusion tensor imaging of post mortem multiple sclerosis brain.

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    Magnetic resonance imaging (MRI) is being used to probe the central nervous system (CNS) of patients with multiple sclerosis (MS), a chronic demyelinating disease. Conventional T(2)-weighted MRI (cMRI) largely fails to predict the degree of patients' disability. This shortcoming may be due to poor specificity of cMRI for clinically relevant pathology. Diffusion tensor imaging (DTI) has shown promise to be more specific for MS pathology. In this study we investigated the association between histological indices of myelin content, axonal count and gliosis, and two measures of DTI (mean diffusivity [MD] and fractional anisotropy [FA]), in unfixed post mortem MS brain using a 1.5-T MR system. Both MD and FA were significantly lower in post mortem MS brain compared to published data acquired in vivo. However, the differences of MD and FA described in vivo between white matter lesions (WMLs) and normal-appearing white matter (NAWM) were retained in this study of post mortem brain: average MD in WMLs was 0.35x10(-3) mm(2)/s (SD, 0.09) versus 0.22 (0.04) in NAWM; FA was 0.22 (0.06) in WMLs versus 0.38 (0.13) in NAWM. Correlations were detected between myelin content (Tr(myelin)) and (i) FA (r=-0.79, p<0.001), (ii) MD (r=0.68, p<0.001), and (iii) axonal count (r=-0.81, p<0.001). Multiple regression suggested that these correlations largely explain the apparent association of axonal count with (i) FA (r=0.70, p<0.001) and (ii) MD (r=-0.66, p<0.001). In conclusion, this study suggests that FA and MD are affected by myelin content and - to a lesser degree - axonal count in post mortem MS brain
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