4,084 research outputs found
Three-Year Longitudinal Service-Learning Research Study: Preliminary Findings
Using an experimental design, this study examines the contributions of service-learning to decreased at-risk behaviors, student cognitive, social, and personal development, and academic achievement over a three-year period. During the pilot phase and Years One and Two, teachers and students from eleven different Ohio schools have been surveyed. Preliminary findings are presented
A Young Solar Twin in the Rosette Cluster NGC 2244 Line of Sight
Based on prior precision photometry and cluster age analysis, the bright star GSC 00154â01819 is a possible young pre-main sequence member of the Rosette cluster, NGC 2244. As part of a comprehensive study of the large-scale structure of the Rosette and its excitation by the cluster stars, we noted this star as a potential backlight for a probe of the interstellar medium and extinction along the sight line towards a distinctive nebular feature projected on to the cluster centre. New high-resolution spectra of the star were taken with the University College London Echelle Spectrograph of the AAT. They reveal that rather than being a reddened spectral type B or A star within the Mon OB2 association, it is a nearby, largely unreddened, solar twin of spectral type G2V less than 180 Myr old. It is about 219 pc from the Sun with a barycentric radial velocity of +14.35 ± 1.99âkmâsâ1. The spectrum of the Rosette behind it and along this line of sight shows a barycentric radial velocity of +26.0 ± 2.4âkmâsâ1 in Hâα, and a full width at half-maximum velocity dispersion of 61.94 ± 1.38âkmâsâ1
Fragment Hotspot Mapping to Identify Selectivity-Determining Regions between Related Proteins.
Funder: ExscientiaFunder: Diamond Light SourceFunder: Kungliga Tekniska HoegskolanFunder: Chinese Center for Disease Control and PreventionFunder: European Federation of Pharmaceutical Industries and AssociationsFunder: European CommissionFunder: Kennedy Trust for Rheumatology ResearchFunder: Ontario Institute for Cancer ResearchFunder: Royal Institution for the Advancement of Learning McGill UniversityFunder: UCBSelectivity is a crucial property in small molecule development. Binding site comparisons within a protein family are a key piece of information when aiming to modulate the selectivity profile of a compound. Binding site differences can be exploited to confer selectivity for a specific target, while shared areas can provide insights into polypharmacology. As the quantity of structural data grows, automated methods are needed to process, summarize, and present these data to users. We present a computational method that provides quantitative and data-driven summaries of the available binding site information from an ensemble of structures of the same protein. The resulting ensemble maps identify the key interactions important for ligand binding in the ensemble. The comparison of ensemble maps of related proteins enables the identification of selectivity-determining regions within a protein family. We applied the method to three examples from the well-researched human bromodomain and kinase families, demonstrating that the method is able to identify selectivity-determining regions that have been used to introduce selectivity in past drug discovery campaigns. We then illustrate how the resulting maps can be used to automate comparisons across a target protein family
Synthesis of the elements in stars: forty years of progress
Forty years ago Burbidge, Burbidge, Fowler, and Hoyle combined what we would now call fragmentary evidence from nuclear physics, stellar evolution and the abundances of elements and isotopes in the solar system as well as a few stars into a synthesis of remarkable ingenuity. Their review provided a foundation for forty years of research in all of the aspects of low energy nuclear experiments and theory, stellar modeling over a wide range of mass and composition, and abundance studies of many hundreds of stars, many of which have shown distinct evidence of the processes suggested by B2FH. In this review we summarize progress in each of these fields with emphasis on the most recent developments
Graphitic carbon nitride stabilized water-in-water emulsions
Aqueous multiphase systems have attracted a lot of interest recently espeically due to target applications in the biomedical field, cosmetics, and food. In turn, waterâinâwater Pickering emulsions are investigated frequently. In here, graphitic carbon nitride (gâCN) stabilized waterâinâwater Pickering emulsions are fabricated via the dextran and poly(ethylene glycol)âbased aqueous twoâphase system. Five different derivatives of gâCN as the Pickering stabilizer are described and the effect of gâCN concentration on droplet sizes is investigated. Stable emulsions (up to 16 weeks) are obtained that can be broken on purpose via various approaches, including dilution, surfactant addition, and most notably light irradiation. The novel approach of waterâinâwater emulsion stabilization via gâCN opens up considerable advances in aqueous multiphase systems and may also introduce photocatalytic properties
HI intensity mapping with the MIGHTEE survey: power spectrum estimates
Intensity mapping (IM) with neutral hydrogen is a promising avenue to probe
the large scale structure of the Universe. With MeerKAT single-dish
measurements, we are constrained to scales degree, and this will allow us
to set important constraints on the Baryon acoustic oscillations and redshift
space distortions. However, with MeerKAT's interferometric observation, we can
also probe relevant cosmological scales. In this paper, we establish that we
can make a statistical detection of HI with one of MeerKAT's existing large
survey projects (MIGHTEE) on semi-linear scales, which will provide a useful
complementarity to the single-dish IM. We present a purpose-built simulation
pipeline that emulates the MIGHTEE observations and forecast the constraints
that can be achieved on the HI power spectrum at for
using the foreground avoidance method. We present the power
spectrum estimates with the current simulation on the COSMOS field that
includes contributions from HI, noise and point source models from the data
itself. The results from our \textit{visibility} based pipeline are in good
agreement to the already available MIGHTEE data. This paper demonstrates that
MeerKAT can achieve very high sensitivity to detect HI with the full MIGHTEE
survey on semi-linear scales (signal-to-noise ratio at
) which are instrumental in probing cosmological quantities such
as the spectral index of fluctuation, constraints on warm dark matter, the
quasi-linear redshift space distortions and the measurement of the HI content
of the Universe up to .Comment: 12 pages, 8 figures, Submitted to MNRAS, comments welcom
Real-Time Green Vegetation Fraction for Land Surface and Numerical Weather Prediction Models
No abstract availabl
Evidence for Charging and Discharging of MoS2 and WS2 on Mica by Intercalating Molecularly Thin Liquid Layers
Transition metal dichalcogenides (TMDCs) are often mechanically exfoliated on mica and examined under ambient conditions. It is known that above a certain relative humidity, a molecularly thin layer of water intercalates between the mica and the TMDC. Herein, the effect of molecularly thin liquid layers on the optical spectra of MoS2 and WS2 exfoliated on dry mica and exposed to the vapors of water, ethanol, and tetrahydrofuran (THF) is investigated. Photoluminescence and differential reflectance (ÎR/R) spectra on the TMDCs on dry mica show dominant trion emission due to n-doping. Intercalation of water removes charge doping and results in purely neutral exciton emission, while an ethanol layer, which can be reversibly exchanged with water, does not completely suppress charge. Similarly, THF intercalates between TMDC and mica, as shown by atomic force microscopy, but it does not suppress the charging of mica. In MoS2 bi- and trilayers, an intercalated water layer leads to a near doubling of the intensity of the indirect band transition. The described charging/discharging of TMDCs by molecular thin liquid layers can provide important clues to better control the optical properties of TMDCs under environmental conditions
Recovery of the Historical SN1957D in X-rays with Chandra
SN1957D, located in one of the spiral arms of M83, is one of the small number
of extragalactic supernovae that has remained detectable at radio and optical
wavelengths during the decades after its explosion. Here we report the first
detection of SN1957D in X-rays, as part of a 729 ks observation of M83 with
\chandra. The X-ray luminosity (0.3 - 8 keV) is 1.7 (+2.4,-0.3) 10**37 ergs/s.
The spectrum is hard and highly self-absorbed compared to most sources in M83
and to other young supernova remnants, suggesting that the system is dominated
at X-ray wavelengths by an energetic pulsar and its pulsar wind nebula. The
high column density may be due to absorption within the SN ejecta. HST WFC3
images resolve the supernova remnant from the surrounding emission and the
local star field. Photometry of stars around SN1957D, using WFC3 images,
indicates an age of less than 10**7 years and a main sequence turnoff mass more
than 17 solar masses. New spectra obtained with Gemini-South show that the
optical spectrum continues to be dominated by broad [O III] emission lines, the
signature of fast-moving SN ejecta. The width of the broad lines has remained
about 2700 km/s (FWHM). The [O III] flux dropped precipitously between 1989 and
1991, but continued monitoring shows the flux has been almost constant since.
In contrast, radio observations over the period 1990-2011 show a decline rate
inf the flux proportional to t**-4, far steeper than the rate observed earlier,
suggesting that the primary shock has overrun the edge of a pre-SN wind.Comment: 28 pages, including 3 tables and 7 figures, accepted for publication
in Ap
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