702 research outputs found
How to Buy a Continent: The Protocols of Indian Treaties as Developed by Benjamin Franklin and Other Members of the American Philosophical Society
In 1743, when Benjamin Franklin announced the formation of an American Philosophical Society for the Promotion of Useful Knowledge, it was important for the citizens of Pennsylvania to know more about their American Indian neighbors. Beyond a slice of land around Philadelphia, three quarters of the province were still occupied by the Delaware and several other Indian tribes, loosely gathered under the wing of an Indian confederacy known as the Six Nations. Relations with the Six Nations and their allies were being peacefully conducted in a series of so-called “Indian Treaties” that dealt with the fur trade, threats of war with France, settlement of grievances, and the purchase of land
Spatially resolved stis spectra of WR + OB binaries with colliding winds
We present spatially resolved spectra of the visual WR + OB massive binaries WR 86, WR 146, and WR 147, obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. The systems are classified as follows: WR 86 = WC 7 + BO III, WR 146 = WC 6 + O8 I-IIf, WR 147 = WN 8 + O5-7 I-II(f). Both WR 146 and WR 147 are known to have strong nonthermal radio emission arising in a wind-wind collision shock zone between the WR and OB components. We find that the spectra of their O companions show Hα profiles in emission, indicative of large mass-loss rates and consistent with the colliding-wind model. Our spectra indicate that the B component in WR 86 has a low mass-loss rate, which possibly explains the fact that WR 86, despite being a long-period WR + OB binary, was not found to be a strong nonthermal radio emitter. Because of the small mass-loss rate of the B-star component in WR 86, the wind collision region must be closer to the B star and smaller in effective area, hence generating smaller amounts of nonthermal radio emission. Absolute magnitudes for all the stars are estimated based on the spectral types of the components (based on the tables by Schmidt-Kaler for OB stars and van der Hucht for WR stars) and compared with actual, observed magnitude differences. While the derived luminosities for the WC 7 and BO III stars in WR 86 are consistent with the observed magnitude difference, we find a discrepancy of at least 1.5 mag between the observed luminosities of the components in each of WR 146 and WR 147 and the absolute magnitudes expected from their spectral types. In both cases, it looks as though either the WR components are about 2 mag too bright for their spectral types or that the O components are about 2 mag too faint. We discuss possible explanations for this apparent discrepancy.Facultad de Ciencias Astronómicas y Geofísica
Hubble Space Telescope Imaging of the WR 38/WR38a Cluster
We are conducting a high angular resolution imaging survey of Galactic
Wolf-Rayet stars using the Wide Field and Planetary Camera 2 aboard the Hubble
Space Telescope. We have found a small stellar cluster associated with the
faint, close pair WR 38 and WR 38a. We present astrometric measurements and
photometry in the wide-band F336W (U), F439W (B), and F555W (V) filter system
for these cluster and nearby stars. We compare their colors and magnitudes with
calibrated model results for reddened stars to identify seven probable main
sequence members of the cluster. A least-squares fit of the colors and
magnitudes of this set yields a cluster reddening of E(B-V) = 1.45 +/- 0.14 mag
and a distance of 3.7^{+3.8}_{-1.2} kpc. We discuss the relationship of this
cluster to other objects along the line of sight, and we argue that the
distance probably lies in the range 5 - 8 kpc (but is not as great as 14.5 kpc
distance recently advocated by Shorlin, Turner, & Pedreros). At a distance of 8
kpc, the cluster would reside in a dense region of the Carina spiral arm, close
to a giant molecular cloud and the starburst cluster NGC 3603.Comment: Submitted to AJ, 24 pages, 3 figures Content is significantly change
A High Angular Resolution Survey of Massive Stars in Cygnus OB2: Results from the Hubble Space Telescope Fine Guidance Sensors
We present results of a high angular resolution survey of massive OB stars in
the Cygnus OB2 association that we conducted with the Fine Guidance Sensor 1R
(FGS1r) on the Hubble Space Telescope. FGS1r is able to resolve binary systems
with a magnitude difference delta-V < 4 down to separations as small as 0.01
arcsec. The sample includes 58 of the brighter members of Cyg OB2, one of the
closest examples of an environment containing a large number of very young and
massive stars. We resolved binary companions for 12 targets and confirmed the
triple nature of one other target, and we offer evidence of marginally resolved
companions for two additional stars. We confirm the binary nature of 11 of
these systems from complementary adaptive optics imaging observations. The
overall binary frequency in our study is 22% to 26% corresponding to orbital
periods ranging from 20 - 20,000 years. When combined with the known
short-period spectroscopic binaries, the results supports the hypothesis that
the binary fraction among massive stars is > 60%. One of the new discoveries is
a companion to the hypergiant star MT 304 = Cyg OB2-12, and future measurements
of orbital motion should provide mass estimates for this very luminous star.Comment: accepted for AJ, 84 pages, 61 figure
Interests in high-functioning autism are more intense, interfering, and idiosyncratic than those in neurotypical development
Although circumscribed interests are pathognomonic with autism, much about these interests remains unknown. Using the Interests Scale (IS), this study compares interests between 76 neurotypical (NT) individuals and 109 individuals with high-functioning autism spectrum disorder (HF-ASD) matched groupwise on age, IQ, and gender ratio. Participants and their parents/caregivers completed diagnostic measures (the Autism Diagnostic Interview—Revised and the Autism Diagnostic Observation Schedule; HF-ASD only), cognitive tests (Wechsler IQ Scales), and questionnaires (the Repetitive Behavior Scale—Revised, the Behavior Rating Inventory of Executive Function, and the Social Responsiveness Scale), in addition to the IS. Consistent with previous research, HF-ASD and NT individuals did not differ in number of interest areas, but the types of interests and intensity of those interests differed considerably. Using only the IS intensity score, 81% of individuals were correctly classified (NT or HF-ASD) in a logistic regression analysis. Among individuals with HF-ASD, Interests Scale scores were significantly related to Autism Diagnostic Observation Schedule, Behavior Rating Inventory of Executive Function, Repetitive Behavior Scale—Revised, and Social Responsiveness Scale scores, but they were not related to Autism Diagnostic Interview—Revised scores, IQ, gender, age, or psychotropic medication use. The type and intensity, but not the number, of interests distinguish high-functioning individuals with ASD from NT individuals
Spatially resolved stis spectra of WR + OB binaries with colliding winds
We present spatially resolved spectra of the visual WR + OB massive binaries WR 86, WR 146, and WR 147, obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. The systems are classified as follows: WR 86 = WC 7 + BO III, WR 146 = WC 6 + O8 I-IIf, WR 147 = WN 8 + O5-7 I-II(f). Both WR 146 and WR 147 are known to have strong nonthermal radio emission arising in a wind-wind collision shock zone between the WR and OB components. We find that the spectra of their O companions show Hα profiles in emission, indicative of large mass-loss rates and consistent with the colliding-wind model. Our spectra indicate that the B component in WR 86 has a low mass-loss rate, which possibly explains the fact that WR 86, despite being a long-period WR + OB binary, was not found to be a strong nonthermal radio emitter. Because of the small mass-loss rate of the B-star component in WR 86, the wind collision region must be closer to the B star and smaller in effective area, hence generating smaller amounts of nonthermal radio emission. Absolute magnitudes for all the stars are estimated based on the spectral types of the components (based on the tables by Schmidt-Kaler for OB stars and van der Hucht for WR stars) and compared with actual, observed magnitude differences. While the derived luminosities for the WC 7 and BO III stars in WR 86 are consistent with the observed magnitude difference, we find a discrepancy of at least 1.5 mag between the observed luminosities of the components in each of WR 146 and WR 147 and the absolute magnitudes expected from their spectral types. In both cases, it looks as though either the WR components are about 2 mag too bright for their spectral types or that the O components are about 2 mag too faint. We discuss possible explanations for this apparent discrepancy.Facultad de Ciencias Astronómicas y Geofísica
In vitro growth and differentiation of primary myoblasts on thiophene based conducting polymers
Polythiophenes are attractive candidate polymers for use in synthetic cell scaffolds as they are amenable to modification of functional groups as a means by which to increase biocompatibility. In the current study we analysed the physical properties and response of primary myoblasts to three thiophene polymers synthesized from either a basic bithiophene monomer or from one of two different thiophene monomers with alkoxy functional groups. In addition, the effect of the dopants pTS- and ClO4 - was investigated. In general, it was found that pTS- doped polymers were significantly smoother and tended to be more hydrophilic than their ClO 4 - doped counterparts, demonstrating that the choice of dopant significantly affects the polythiophene physical properties. These properties had a significant effect on the response of primary myoblasts to the polymer surfaces; LDH activity measured from cells harvested at 24 and 48 h post-seeding revealed significant differences between numbers of cells attaching to the different thiophene polymers, whilst all of the polymers equally supported cell doubling over the 48 h period. Differences in morphology were also observed, with reduced cell spreading observed on polymers with alkoxy groups. In addition, significant differences were seen in the polymers\u27 ability to support myoblast fusion. In general pTS- doped polymers were better able to support fusion than their ClO4 - doped counterparts. These studies demonstrate that modification of thiophene polymers can be used to promote specific cellular response (e.g. proliferation over differentiation) without the use of biological agents. 2013 The Royal Society of Chemistry
Spatially resolved STIS spectra of WR+OB binaries with colliding winds
We present spatially resolved spectra of the visual WR+OB massive binaries
WR86, WR146, and WR147, obtained with the Space Telescope Imaging Spectrograph
on board the Hubble Space Telescope. The systems are classified as follows:
WR86 = WC7 + B0 III, WR146 = WC6 + O8 I-IIf, WR147 = WN8 + O5-7 I-II(f). Both
WR146 and WR147 are known to have strong non-thermal radio emission arising in
a wind-wind collision shock zone between the WR and OB components. We find that
the spectra of their O companions show Halpha profiles in emission, indicative
of large mass-loss rates, and consistent with the colliding-wind model. Our
spectra indicate that the B component in WR86 has a low mass-loss rate, which
possibly explains the fact that WR86, despite being a long period WR+OB binary,
was not found to be a strong non-thermal radio emitter. Because of the small
mass-loss rate of the B star component in WR86, the wind collision region must
be closer to the B star and smaller in effective area, hence generating smaller
amounts of non-thermal radio emission. Absolute magnitudes for all the stars
are estimated based on the spectral types of the components (based on the
tables by Schmidt-Kaler for OB stars, and van der Hucht for WR stars), and
compared with actual, observed magnitude differences. While the derived
luminosities for the WC7 and B0 III stars in WR86 are consistent with the
observed magnitude difference, we find a discrepancy of at least 1.5 magnitudes
between the observed luminosities of the components in each of WR146 and WR147
and the absolute magnitudes expected from their spectral types. In both cases,
it looks as though either the WR components are about 2 magnitudes too bright
for their spectral types, or that the O components are about 2 magnitudes too
faint. We discuss possible explanations for this apparent discrepancy.Comment: Accepted for publication in the Astronomical Journa
A soft 3D polyacrylate hydrogel recapitulates the cartilage niche and allows growth-factor free tissue engineering of human articular cartilage
Cartilage degeneration or damage treatment is still a challenge, but, tissue engineering strategies, which
combine cell therapy strategies, which combine cell therapy and scaffolds, and have emerged as a
promising new approach. In this regard, polyurethanes and polyacrylates polymers have been shown
to have clinical potential to treat osteochondral injuries. Here, we have used polymer microarrays technology
to screen 380 different polyurethanes and polyacrylates polymers. The top polymers with potential
to maintain chondrocyte viability were selected, with scale-up studies performed to evaluate their
ability to support chondrocyte proliferation during long-term culture, while maintaining their characteristic
phenotype. Among the selected polymers, poly (methylmethacrylate-co-methacrylic acid), showed
the highest level of chondrogenic potential and was used to create a 3D hydrogel. Ultrastructural morphology,
microstructure and mechanical testing of this novel hydrogel revealed robust characteristics
to support chondrocyte growth. Furthermore, in vitro and in vivo biological assays demonstrated that
chondrocytes cultured on the hydrogel had the capacity to produce extracellular matrix similar to hyaline
cartilage, as shown by increased expression of collagen type II, aggrecan and Sox9, and the reduced
expression of the fibrotic marker’s collagen type I. In conclusion, hydrogels generated from poly
(methylmethacrylate-co-methacrylic acid) created the appropriate niche for chondrocyte growth and
phenotype maintenance and might be an optimal candidate for cartilage tissue-engineering applications.This work was supported by the Consejería de Economía, Innovación
y Ciencia (Junta de Andalucía, excellence project number
CTS-6568) and by the Ministerio de Economía, Industria y Competitividad
(FEDER funds, project RTC-2016-5451-1). We acknowledge
the Junta de Andalucía for providing a fellowship granted to
G.J. and the MINECO for providing a post-doctoral fellowship to
E.L-R (project RTC-2016-5451-1). MBR/SV thank the European
Research Council (Advanced Grant ADREEM ERC-2013-340469)
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