78 research outputs found
Making the Walvis Bay Corridors Safer for Truck Drivers through a Dedicated Smartphone Application
This project culminated in an interactive prototype of a smartphone application for the Walvis Bay Corridor Group, who wants to use mobile communication technology to assist truck drivers on the Walvis Bay Corridors. We conducted interviews to understand the needs of the end users and proposed functionalities that best address those needs. We then produced an interactive prototype of a user interface that captures these functionalities in an intuitive and user-friendly way. In addition, the team also performed extensive data collection to support the proposed functionalities and recommended future steps for the development of a full-fledged application
Design and Development of a Myoelectric Transradial Prosthesis
The loss of a limb is a life-changing event and reality for 441,000 transradial amputees in the United States. Limb loss can have substantial physical, social, psychological, and economic consequences. A prototype prosthesis was created that has sophisticated hand functionality, an adjustable and comfortable socket, and a lightweight yet durable design utilizing 3D printing, all available at a reasonable price point. The prosthesis integrated force sensors, servo motors, and a myoelectric means of control so the user may perform activities of daily living. The overall outcome was a prosthesis that met its design requirements, offering increased usability, functionality, and availability
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Machines vs Malaria: A Flow-Based Preparation of the Drug Candidate OZ439.
An efficient preparation of the antimalarial drug candidate OZ439, which was obtained by integrating a machine-assisted approach with batch processes, is reported. This approach allows a rapid and cost-effective production of the key intermediates that were readily elaborated into the target molecule.We are grateful to Croucher Foundation and Cambridge Trust (SHL), MEC-Spain (FPU-predoctoral grants, AG), Pfizer World-wide Research and Development (CB), the Xunta de Galicia Gov-ernment (JAS), and the EPSRC (SVL, grant n° EP/K0099494/1 and EP/K039520/1) for financial support.This is the final version. It first appeared at http://pubs.acs.org/doi/abs/10.1021/acs.orglett.5b01307
Elemental Abundances of Kepler Objects of Interest in APOGEE. I. Two Distinct Orbital Period Regimes Inferred from Host Star Iron Abundances
The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has
observed 600 transiting exoplanets and exoplanet candidates from
\textit{Kepler} (Kepler Objects of Interest, KOIs), most with 18 epochs.
The combined multi-epoch spectra are of high signal-to-noise (typically
100) and yield precise stellar parameters and chemical abundances. We
first confirm the ability of the APOGEE abundance pipeline, ASPCAP, to derive
reliable [Fe/H] and effective temperatures for FGK dwarf stars -- the primary
\textit{Kepler} host stellar type -- by comparing the ASPCAP-derived stellar
parameters to those from independent high-resolution spectroscopic
characterizations for 221 dwarf stars in the literature. With a sample of 282
close-in ( days) KOIs observed in the APOGEE KOI goal program, we find a
correlation between orbital period and host star [Fe/H] characterized by a
critical period, = days, below which small
exoplanets orbit statistically more metal-enriched host stars. This effect may
trace a metallicity dependence of the protoplanetary disk inner-radius at the
time of planet formation or may be a result of rocky planet ingestion driven by
inward planetary migration. We also consider that this may trace a metallicity
dependence of the dust sublimation radius, but find no statistically
significant correlation with host and orbital period to
support such a claim.Comment: 18 Pages, Accepted to A
Design and Development of a Myoelectric Transradial Prosthesis
The loss of a limb is a life-changing event and reality for 441,000 transradial amputees in the United States. Limb loss can have substantial physical, social, psychological, and economic consequences. A prototype prosthesis was created that has sophisticated hand functionality, an adjustable and comfortable socket, and a lightweight yet durable design utilizing 3D printing, all available at a reasonable price point. The prosthesis integrated force sensors, servo motors, and a myoelectric means of control so the user may perform activities of daily living. The overall outcome was a prosthesis that met its design requirements, offering increased usability,functionality, and availability
Chemical abundance gradients from open clusters in the Milky Way disk: results from the APOGEE survey
Metallicity gradients provide strong constraints for understanding the
chemical evolution of the Galaxy. We report on radial abundance gradients of
Fe, Ni, Ca, Si, and Mg obtained from a sample of 304 red-giant members of 29
disk open clusters, mostly concentrated at galactocentric distances between ~8
- 15 kpc, but including two open clusters in the outer disk. The observations
are from the APOGEE survey. The chemical abundances were derived automatically
by the ASPCAP pipeline and these are part of the SDSS III Data Release 12. The
gradients, obtained from least squares fits to the data, are relatively flat,
with slopes ranging from -0.026 to -0.033 dex/kpc for the alpha-elements [O/H],
[Ca/H], [Si/H] and [Mg/H] and -0.035 dex/kpc and -0.040 dex/kpc for [Fe/H] and
[Ni/H], respectively. Our results are not at odds with the possibility that
metallicity ([Fe/H]) gradients are steeper in the inner disk (R_GC ~7 - 12 kpc)
and flatter towards the outer disk. The open cluster sample studied spans a
significant range in age. When breaking the sample into age bins, there is some
indication that the younger open cluster population in our sample (log age <
8.7) has a flatter metallicity gradient when compared with the gradients
obtained from older open clusters.Comment: 4 pages, 3 figures, To appear in Astronomische Nachrichten, special
issue "Reconstruction the Milky Way's History: Spectroscopic surveys,
Asteroseismology and Chemo-dynamical models", Guest Editors C. Chiappini, J.
Montalb\'an, and M. Steffen, AN 2016 (in press)
Stellar and Planetary Characterization of the Ross 128 Exoplanetary System from APOGEE Spectra
The first detailed chemical abundance analysis of the M dwarf (M4.0)
exoplanet-hosting star Ross 128 is presented here, based upon near-infrared
(1.5--1.7 \micron) high-resolution (22,500) spectra from the
SDSS-APOGEE survey. We determined precise atmospheric parameters =3231100K, log=4.960.11 dex and chemical abundances of eight
elements (C, O, Mg, Al, K, Ca, Ti, and Fe), finding Ross 128 to have near solar
metallicity ([Fe/H] = +0.030.09 dex). The derived results were obtained
via spectral synthesis (1-D LTE) adopting both MARCS and PHOENIX model
atmospheres; stellar parameters and chemical abundances derived from the
different adopted models do not show significant offsets. Mass-radius modeling
of Ross 128b indicate that it lies below the pure rock composition curve,
suggesting that it contains a mixture of rock and iron, with the relative
amounts of each set by the ratio of Fe/Mg. If Ross 128b formed with a sub-solar
Si/Mg ratio, and assuming the planet's composition matches that of the
host-star, it likely has a larger core size relative to the Earth. The derived
planetary parameters -- insolation flux (S=1.790.26) and
equilibrium temperature (=29410K) -- support previous findings
that Ross 128b is a temperate exoplanet in the inner edge of the habitable
zone.Comment: Accepted in ApJLetters, 3 figures, 2 tables, 12 page
Sodium and Oxygen Abundances in the Open Cluster NGC 6791 from APOGEE H-Band Spectroscopy
The open cluster NGC 6791 is among the oldest, most massive and metal-rich
open clusters in the Galaxy. High-resolution -band spectra from the Apache
Point Observatory Galactic Evolution Experiment (APOGEE) of 11 red giants in
NGC 6791 are analyzed for their chemical abundances of iron, oxygen, and
sodium. The abundances of these three elements are found to be homogeneous
(with abundance dispersions at the level of 0.05 - 0.07 dex) in these
cluster red giants, which span much of the red-giant branch (T
3500K - 4600K), and include two red-clump giants. From the infrared
spectra, this cluster is confirmed to be among the most metal-rich clusters in
the Galaxy ( = 0.34 0.06), and is found to have a roughly
solar value of [O/Fe] and slightly enhanced [Na/Fe]. Non-LTE calculations for
the studied Na I lines in the APOGEE spectral region (16373.86\AA\ and
16388.85\AA) indicate only small departures from LTE ( 0.04 dex)
for the parameter range and metallicity of the studied stars. The previously
reported double population of cluster members with different Na abundances is
not found among the studied sample.Comment: Accepted for publication at ApJ Letter
APOGEE Data and Spectral Analysis from SDSS Data Release 16: Seven Years of Observations Including First Results from APOGEE-South
The spectral analysis and data products in Data Release 16 (DR16; December
2019) from the high-resolution near-infrared APOGEE-2/SDSS-IV survey are
described. Compared to the previous APOGEE data release (DR14; July 2017),
APOGEE DR16 includes about 200000 new stellar spectra, of which 100000 are from
a new southern APOGEE instrument mounted on the 2.5 m du Pont telescope at Las
Campanas Observatory in Chile. DR16 includes all data taken up to August 2018,
including data released in previous data releases. All of the data have been
re-reduced and re-analyzed using the latest pipelines, resulting in a total of
473307 spectra of 437445 stars. Changes to the analysis methods for this
release include, but are not limited to, the use of MARCS model atmospheres for
calculation of the entire main grid of synthetic spectra used in the analysis,
a new method for filling "holes" in the grids due to unconverged model
atmospheres, and a new scheme for continuum normalization. Abundances of the
neutron capture element Ce are included for the first time. A new scheme for
estimating uncertainties of the derived quantities using stars with multiple
observations has been applied, and calibrated values of surface gravities for
dwarf stars are now supplied. Compared to DR14, the radial velocities derived
for this release more closely match those in the Gaia DR2 data base, and a
clear improvement in the spectral analysis of the coolest giants can be seen.
The reduced spectra as well as the result of the analysis can be downloaded
using links provided in the SDSS DR16 web page
Stellar Characterization and Radius Inflation of Hyades M Dwarf Stars From the APOGEE Survey
We present a spectroscopic analysis of a sample of 48 M dwarf stars () from the Hyades open cluster using
high-resolution H-band spectra from the SDSS/APOGEE survey. Our methodology
adopts spectrum synthesis with LTE MARCS model atmospheres, along with the
APOGEE DR17 line list, to determine effective temperatures, surface gravities,
metallicities, and projected rotational velocities. The median metallicity
obtained for the Hyades M dwarfs is [M/H]= 0.090.03 dex, indicating a
small internal uncertainty and good agreement with optical results for Hyades
red-giants. Overall, the median radii are larger than predicted by stellar
models by 1.62.3\% and 2.42.3\%, relative to a MIST and DARTMOUTH
isochrone, respectively. We emphasize, however, that these isochrones are
different and the fractional radius inflation for the fully- and
partially-convective regimes have distinct behaviors depending on the
isochrone. Using a MIST isochrone there is no evidence of radius inflation for
the fully convective stars, while for the partially convective M-dwarfs the
radii are inflated by 2.72.1\%, which is in agreement with predictions
from models that include magnetic fields. For the partially-convective stars,
rapid-rotators present on average higher inflation levels than slow-rotators.
The comparison with SPOTS isochrone models indicates that the derived M dwarf
radii can be explained by accounting for stellar spots in the photosphere of
the stars, with 76\% of the studied M dwarfs having up to 20\% spot coverage,
and the most inflated stars with 20 -- 40\% spot coverage.Comment: Accepted for publication by The Astrophysical Journal (ApJ
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