University of Waterloo

About: University of Waterloo is a education organization based out in Waterloo, Ontario, Canada. It is known for research contribution in the topics: Population & Poison control. The organization has 36093 authors who have published 93906 publications receiving 2948139 citations. The organization is also known as: UW & uwaterloo.

Validation of the Aura Microwave Limb Sounder temperature and geopotential height measurements

Abstract: This paper describes the retrievals algorithm used to determine temperature and height from radiance measurements by the Microwave Limb Sounder on EOS Aura. MLS is a "limbscanning" instrument, meaning that it views the atmosphere along paths that do not intersect the surface - it actually looks forwards from the Aura satellite. This means that the temperature retrievals are for a "profile" of the atmosphere somewhat ahead of the satellite. Because of the need to view a finite sample of the atmosphere, the sample spans a box about 1.5km deep and several tens of kilometers in width; the optical characteristics of the atmosphere mean that the sample is representative of a tube about 200-300km long in the direction of view. The retrievals use temperature analyses from NASA's Goddard Earth Observing System, Version 5 (GEOS-5) data assimilation system as a priori states. The temperature retrievals are somewhat deperrde~zt on these a priori states, especially in the lower stratosphere. An important part of the validation of any new dataset involves comparison with other, independent datasets. A large part of this study is concerned with such comparisons, using a number of independent space-based measurements obtained using different techniques, and with meteorological analyses. The MLS temperature data are shown to have biases that vary with height, but also depend on the validation dataset. MLS data are apparently biased slightly cold relative to correlative data in the upper troposphere and slightly warm in the middle stratosphere. A warm MLS bias in the upper stratosphere may be due to a cold bias in GEOS-5 temperatures.

Meta-omics analysis of elite athletes identifies a performance-enhancing microbe that functions via lactate metabolism.

Abstract: The human gut microbiome is linked to many states of human health and disease1. The metabolic repertoire of the gut microbiome is vast, but the health implications of these bacterial pathways are poorly understood. In this study, we identify a link between members of the genus Veillonella and exercise performance. We observed an increase in Veillonella relative abundance in marathon runners postmarathon and isolated a strain of Veillonella atypica from stool samples. Inoculation of this strain into mice significantly increased exhaustive treadmill run time. Veillonella utilize lactate as their sole carbon source, which prompted us to perform a shotgun metagenomic analysis in a cohort of elite athletes, finding that every gene in a major pathway metabolizing lactate to propionate is at higher relative abundance postexercise. Using 13C3-labeled lactate in mice, we demonstrate that serum lactate crosses the epithelial barrier into the lumen of the gut. We also show that intrarectal instillation of propionate is sufficient to reproduce the increased treadmill run time performance observed with V. atypica gavage. Taken together, these studies reveal that V. atypica improves run time via its metabolic conversion of exercise-induced lactate into propionate, thereby identifying a natural, microbiome-encoded enzymatic process that enhances athletic performance.

A relationship between AGN jet power and radio power

Abstract: Using Chandra X-ray and Very Large Array radio data, we investigate the scaling relationship between jet power, P{sub jet}, and synchrotron luminosity, P{sub radio}. We expand the sample presented in BIrzan et al. to lower radio power by incorporating measurements for 21 giant elliptical galaxies (gEs) to determine if the BIrzan et al. P{sub jet}-P {sub radio} scaling relations are continuous in form and scatter from gEs up to brightest cluster galaxies. We find a mean scaling relation of P {sub jet} {approx} 5.8 x 10{sup 43}(P{sub radio}/10{sup 40}){sup 0.70} erg s{sup -1} which is continuous over {approx}6-8 decades in P{sub jet} and P{sub radio} with a scatter of {approx} 0.7 dex. Our mean scaling relationship is consistent with the model presented in Willott et al. if the typical fraction of lobe energy in non-radiating particles to that in relativistic electrons is {approx}>100. We identify several gEs whose radio luminosities are unusually large for their jet powers and have radio sources which extend well beyond the densest parts of their X-ray halos. We suggest that these radio sources are unusually luminous because they were unable to entrain appreciable amounts of gas.

Recent advances in the application of cellulose nanocrystals

Abstract: This review describes recent advances on the application of cellulose nanocrystals (CNCs) in selected applications. CNCs are produced via acid hydrolysis of cellulosic materials, such as wood, cotton, tunicate, or other biomass. It possesses many desirable properties, such as large surface area, high tensile strength and stiffness, excellent colloidal stability, and potential for modification due to the abundance of surface hydroxyl groups. By modifying its surface with small molecules, polymers, and nanoparticles, they can be utilized as a zero-dimension nanostructure for drug delivery, spun into 1-dimension fibers for enhanced strength, cast into 2-dimension films for flexibility, or molded into 3-dimension hydrogels and aerogels for compressibility or porous materials. The use and impact of CNCs in three industrial sectors: biomedical, wastewater treatment, energy and electronics are described and discussed, and we will offer our perspective on the future and new applications of this sustainable nanomaterial.

The influence of postural threat on the control of upright stance.

Abstract: In order to utilize static posturography as a tool with which to diagnose pathological balance disorders, it is necessary to understand the contribution of psychological factors such as fear of falling. In this study we examined kinetic and kinematic parameters during quiet stance of eight young healthy adults standing under three conditions which posed increasing levels of postural threat. Participants were required to stand quietly, both with and without visual information and with normal or reduced vestibular information for 2-min periods at each of three surface conditions: ground level (low threat), 81 cm above the ground completely surrounded by a support surface (medium threat) and 81 cm above ground at the edge of the surface (high threat). In addition to calculating displacement and frequency measures for movements of centre of pressure (COP) and centre of mass (COM), a measure of stiffness was derived from the difference between COP-COM signal. Mean EMG activity was recorded bilaterally from anterior and posterior muscles of the lower and upper leg. A stiffening strategy was adopted when individuals stood under high threat conditions involving significant changes in kinematic, kinetic and EMG variables. The A-P stiffness constant increased significantly (27.5%) for the high threat compared to low threat condition, independent of vision or vestibular information. Changes in stiffness were accompanied by: (1) backward shift of the mean A-P position of COP and COM, (2) increased mean power frequency and decreased amplitude displacement of the COP and (3) decreased amplitude displacements of the COM. Of the significant changes observed in mean EMG activity with increased postural threat, only tibialis anterior was significantly correlated with increased stiffness, while activity in soleus, medial gastrocnemius and rectus femoris was highly correlated with mean position of COP.