2,149 research outputs found
Comparison between qualitative and quantitative measurement in assessing thermal comfort in an elementary school
We compare qualitative and quantitative measurements to assess an elementary school buildingâs thermal comfort. Quantitative measurements of the physical environment are useful but not sufficient, since different people respond differently in the same indoor environment. A qualitative survey of the school employees shows the thermal comfort level has a 3.73 out of 7 score and 40% of subjects rated it unsatisfactory, even though the temperature and humidity level are measured within the comfort range recommended by ASHERA 90.1 â 2004. This gap occurs because human metabolism is not taken into account in current design guidelines, even though there is a clear correlation between human metabolic level and perceived thermal comfort. The gap between design guidelines and occupantsâ thermal comfort presents an opportunity to improve indoor environmental quality. School buildings are especially challenging because they have a mix of adult and child occupants with widely varying metabolic rates. Therefore, an elementary school was used as a case study to compare differences between quantitative and qualitative measurement. We conducted a series of simulations to compare the thermal comfort in relation to adult and childrenâs metabolism and their thermal responses. We demonstrate that the negligence of occupantsâ metabolism can lead to inaccurate design guidelines for the physical environmentâs thermal comfort. Our results could potentially improve design manuals to accommodate buildings with mixed occupants to maximize comfort levels
Variation in Emission and Absorption Lines and Continuum Flux by Orbital Phase in Vela X-1
High resolution spectral studies were undertaken at orbital phases 0, 0.25
and 0.5 on the high-mass X-ray binary (HMXB) Vela X-1 using archival Chandra
data. We present (a) the first detailed analysis of the multiple strong narrow
emission lines present in phase 0.5 (b) an analysis of the absorption of the
continuum in phase 0.5, and (c) the first detection of narrow emission and
absorption lines in phase 0.25. Multiple fluorescent and H-and He-like emission
lines in the band 1.6 - 20 Angstrom in eclipse are partially obscured at phase
0.25 by the X-ray continuum. The phase 0.25 spectrum displays 3 triplets, 2
with a blue-shifted resonance (r) line in absorption and the intercombination
(i) and forbidden (f) lines in emission, and shows in absorption other
blue-shifted lines seen in emission in eclipse. At phase 0.5 the soft X-ray
continuum diminishes revealing an "eclipse-like" spectrum, however line flux
values are around 13-fold those in eclipse. We conclude the narrow emission
lines in Vela X-1 become apparent when the continuum is blocked from line of
sight, either by eclipse or by scattering and/or absorption from a wake or
cloud. The H-and He-like lines arise in warm photoionised regions in the
stellar wind, while the fluorescent lines (including a Ni K alpha line) are
produced in cooler clumps of gas outside these regions. Absorption of the 5-13
Angstrom continuum at phase 0.5 may be caused by an accretion wake comprised of
dense stagnant photoionized plasma inside a Stromgren zone. Multiple
fluorescent emission lines may be a common feature of the supergiant category
of HMXBs.Comment: 29 pages, 7 figures, accepted for publication in the Astronomical
Journa
Modeling comprehensive chemical composition of weathered oil following a marine spill to predict ozone and potential secondary aerosol formation and constrain transport pathways
Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 120 (2015): 7300â7315, doi:10.1002/2015JC011093.Releases of hydrocarbons from oil spills have large environmental impacts in both the ocean and atmosphere. Oil evaporation is not simply a mechanism of mass loss from the ocean, as it also causes production of atmospheric pollutants. Monitoring atmospheric emissions from oil spills must include a broad range of volatile organic compounds (VOC), including intermediate-volatile and semivolatile compounds (IVOC, SVOC), which cause secondary organic aerosol (SOA) and ozone production. The Deepwater Horizon (DWH) disaster in the northern Gulf of Mexico during Spring/Summer of 2010 presented a unique opportunity to observe SOA production due to an oil spill. To better understand these observations, we conducted measurements and modeled oil evaporation utilizing unprecedented comprehensive composition measurements, achieved by gas chromatography with vacuum ultraviolet time of flight mass spectrometry (GC-VUV-HR-ToFMS). All hydrocarbons with 10â30 carbons were classified by degree of branching, number of cyclic rings, aromaticity, and molecular weight; these hydrocarbons comprise âŒ70% of total oil mass. Such detailed and comprehensive characterization of DWH oil allowed bottom-up estimates of oil evaporation kinetics. We developed an evaporative model, using solely our composition measurements and thermodynamic data, that is in excellent agreement with published mass evaporation rates and our wind-tunnel measurements. Using this model, we determine surface slick samples are composed of oil with a distribution of evaporative ages and identify and characterize probable subsurface transport of oil.Funded by Gulf of Mexico Research Initiative2016-05-0
Fluid-membrane tethers: minimal surfaces and elastic boundary layers
Thin cylindrical tethers are common lipid bilayer membrane structures,
arising in situations ranging from micromanipulation experiments on artificial
vesicles to the dynamic structure of the Golgi apparatus. We study the shape
and formation of a tether in terms of the classical soap-film problem, which is
applied to the case of a membrane disk under tension subject to a point force.
A tether forms from the elastic boundary layer near the point of application of
the force, for sufficiently large displacement. Analytic results for various
aspects of the membrane shape are given.Comment: 12 page
In Vivo Emergence of a Novel Protease Inhibitor Resistance Signature in HIV-1 Matrix.
Protease inhibitors (PIs) are the second- and last-line therapy for the majority of HIV-infected patients worldwide. Only around 20% of individuals who fail PI regimens develop major resistance mutations in protease. We sought to explore the role of mutations in gag-pro genotypic and phenotypic changes in viruses from six Nigerian patients who failed PI-based regimens without known drug resistance-associated protease mutations in order to identify novel determinants of PI resistance. Target enrichment and next-generation sequencing (NGS) with the Illumina MiSeq system were followed by haplotype reconstruction. Full-length Gag-protease gene regions were amplified from baseline (pre-PI) and virologic failure (VF) samples, sequenced, and used to construct gag-pro-pseudotyped viruses. Phylogenetic analysis was performed using maximum-likelihood methods. Susceptibility to lopinavir (LPV) and darunavir (DRV) was measured using a single-cycle replication assay. Western blotting was used to analyze Gag cleavage. In one of six participants (subtype CRF02_AG), we found 4-fold-lower LPV susceptibility in viral clones during failure of second-line treatment. A combination of four mutations (S126del, H127del, T122A, and G123E) in the p17 matrix of baseline virus generated a similar 4-fold decrease in susceptibility to LPV but not darunavir. These four amino acid changes were also able to confer LPV resistance to a subtype B Gag-protease backbone. Western blotting demonstrated significant Gag cleavage differences between sensitive and resistant isolates in the presence of drug. Resistant viruses had around 2-fold-lower infectivity than sensitive clones in the absence of drug. NGS combined with haplotype reconstruction revealed that resistant, less fit clones emerged from a minority population at baseline and thereafter persisted alongside sensitive fitter viruses. We used a multipronged genotypic and phenotypic approach to document emergence and temporal dynamics of a novel protease inhibitor resistance signature in HIV-1 matrix, revealing the interplay between Gag-associated resistance and fitness
FCIC memo of staff interview with Institute for International Economics (IIE)
Additional IIE staff were also present during this interview
LSST: from Science Drivers to Reference Design and Anticipated Data Products
(Abridged) We describe here the most ambitious survey currently planned in
the optical, the Large Synoptic Survey Telescope (LSST). A vast array of
science will be enabled by a single wide-deep-fast sky survey, and LSST will
have unique survey capability in the faint time domain. The LSST design is
driven by four main science themes: probing dark energy and dark matter, taking
an inventory of the Solar System, exploring the transient optical sky, and
mapping the Milky Way. LSST will be a wide-field ground-based system sited at
Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m
effective) primary mirror, a 9.6 deg field of view, and a 3.2 Gigapixel
camera. The standard observing sequence will consist of pairs of 15-second
exposures in a given field, with two such visits in each pointing in a given
night. With these repeats, the LSST system is capable of imaging about 10,000
square degrees of sky in a single filter in three nights. The typical 5
point-source depth in a single visit in will be (AB). The
project is in the construction phase and will begin regular survey operations
by 2022. The survey area will be contained within 30,000 deg with
, and will be imaged multiple times in six bands, ,
covering the wavelength range 320--1050 nm. About 90\% of the observing time
will be devoted to a deep-wide-fast survey mode which will uniformly observe a
18,000 deg region about 800 times (summed over all six bands) during the
anticipated 10 years of operations, and yield a coadded map to . The
remaining 10\% of the observing time will be allocated to projects such as a
Very Deep and Fast time domain survey. The goal is to make LSST data products,
including a relational database of about 32 trillion observations of 40 billion
objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures
available from https://www.lsst.org/overvie
Constraining the fluid history of a CO2 -H2 S reservoir: insights from stable isotopes, REE and fluid inclusion microthermometry
Reservoirs that host CO2âH2Sâbearing gases provide a key insight into crustal redox reactions such as thermochemical sulfate reduction (TSR). Despite this, there remains a poor understanding of the extent, duration, and the factors limiting this process on a reservoir scale. Here we show how a combination of petrography, fluid inclusion, rare earth element (REE), and carbon (ÎŽ13C), oxygen (ÎŽ18O), and sulfur (ÎŽ34S) stable isotope data can disentangle the fluid history of the world's largest CO2 accumulation, the LaBarge Field in Wyoming, USA. The carbonateâhosted LaBarge Field was charged with oil around 80 Ma ago, which together with nodular anhydrite represent the reactants for TSR. The nodules exhibit two distinct trends of evolution in ÎŽ13C with both ÎŽ34S and ÎŽ18O that may be coupled to two different processes. The first trend was interpreted to reflect the coupled dissolution of anhydrite and reduction to elemental sulfur and the oxidation of organic compounds and associated precipitation of calcite during TSR. In contrast, the second trend was interpreted to be the result of the hydrothermal CO2 influx after the cessation of TSR. In addition, mass balance calculations were performed to estimate an approximate TSR reaction duration of 80 ka and to identify the availability of organic compounds as the limiting factor of the TSR process. Such an approach provides a tool for the prediction of TSR occurrence elsewhere and advancing our understanding of crustal fluid interactions
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