8,445 research outputs found
Solar radiation force modeling for TDRS orbit determination
The relative orbit determination accuracies resulting from several TDRS models are evaluated. These models include spherical, single-plate, and restricted two-plate models. The plate models can be adjusted in both area and reflectivity through differential correction. The restricted two-plate model has an Earth-pointing plate and a solar plate; the orientation of the solar plate is restricted to rotation about an axis perpendicular to the satellite's orbital plane
Infrared and Radio observations of a small group of protostellar objects in the molecular core, L1251-C
We present a multi-wavelength observational study of a low-mass star-forming
region, L1251-C, with observational results at wavelengths from the
near-infrared to the millimeter. Spitzer Space Telescope observations confirmed
that IRAS 22343+7501 is a small group of protostellar objects. The extended
emission to east-west direction with its intensity peak at the center of L1251A
has been detected at 350 and 850 micron with the CSO and JCMT telescopes,
tracing dense envelope materials around L1251A. The single-dish data from the
KVN and TRAO telescopes show inconsistencies between the intensity peaks of
several molecular line emission and that of the continuum emission, suggesting
complex distributions of molecular abundances around L1251A. The SMA
interferometer data, however, show intensity peaks of CO 2-1 and 13CO 2-1
located at the position of IRS 1, which is both the brightest source in IRAC
image and the weakest source in the 1.3 mm dust continuum map. IRS 1 is the
strongest candidate for the driving source of the newly detected compact CO 2-1
outflow. Over the whole region (14' by 14') of L125l-C, 3 Class I and 16 Class
II sources have been detected, including three YSOs in L1251A. A comparison
with the average projected distance among 19 YSOs in L1251-C and that among 3
YSOs in L1251A suggests L1251-C is an example of low-mass cluster formation,
where protostellar objects are forming in a small group.Comment: 53 pages, 19 figures, accepted for publication in ApJ
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Infrared and Radio Observations of a Small Group of Protostellar Objects in the Molecular Core, L1251-C
We present a multi-wavelength observational study of a low-mass star-forming region, L1251-C, with observational results at wavelengths from the near-infrared to the millimeter. Spitzer Space Telescope observations confirmed that IRAS 22343+7501 is a small group of protostellar objects. The extended emission in the east-west direction with its intensity peak at the center of L1251A has been detected at 350 and 850 mu m with the Caltech Submillimeter Observatory and James Clerk Maxwell telescopes, tracing dense envelope material around L1251A. The single-dish data from the Korean VLBI Network and TRAO telescopes show inconsistencies between the intensity peaks of several molecular emission lines and that of the continuum emission, suggesting complex distributions of molecular abundances around L1251A. The Submillimeter Array interferometer data, however, show intensity peaks of CO 2-1 and (CO)-C-13 2-1 located at the position of IRS 1, which is both the brightest source in the Infrared Array Camera image and the weakest source in the 1.3 mm dust-continuum map. IRS 1 is the strongest candidate for the driving source of the newly detected compact CO 2-1 outflow. Over the entire region (14' x 14') of L125l-C, 3 Class I and 16 Class II sources have been detected, including three young stellar objects (YSOs) in L1251A. A comparison between the average projected distance among the 19 YSOs in L1251-C and that among the 3 YSOs in L1251A suggests that L1251-C is an example of low-mass cluster Formation where protostellar objects form in a small group.Basic Science Research Program through the National Research Foundation of Korea (NRF) - Ministry of Education of the Korean government NRF-2012R1A1A2044689BK21 plus program through the National Research Foundation (NRF) - Ministry of Education of KoreaKorea Astronomy and Space Science Institute (KASI) grant - Korea government (MEST)National Science Foundation 0708158NASA NNX13AE54G, 1224608, 1230782, 1407Astronom
Hubble and Spitzer Observations of an Edge-on Circumstellar Disk around a Brown Dwarf
We present observations of a circumstellar disk that is inclined close to
edge-on around a young brown dwarf in the Taurus star-forming region. Using
data obtained with SpeX at the NASA Infrared Telescope Facility, we find that
the slope of the 0.8-2.5 um spectrum of the brown dwarf 2MASS J04381486+2611399
cannot be reproduced with a photosphere reddened by normal extinction. Instead,
the slope is consistent with scattered light, indicating that circumstellar
material is occulting the brown dwarf. By combining the SpeX data with mid-IR
photometry and spectroscopy from the Spitzer Space Telescope and previously
published millimeter data from Scholz and coworkers, we construct the spectral
energy distribution for 2MASS J04381486+2611399 and model it in terms of a
young brown dwarf surrounded by an irradiated accretion disk. The presence of
both silicate absorption at 10 um and silicate emission at 11 um constrains the
inclination of the disk to be ~70 deg, i.e. ~20 deg from edge-on. Additional
evidence of the high inclination of this disk is provided by our detection of
asymmetric bipolar extended emission surrounding 2MASS J04381486+2611399 in
high-resolution optical images obtained with the Hubble Space Telescope.
According to our modeling for the SED and images of this system, the disk
contains a large inner hole that is indicative of a transition disk (R_in~58
R_star~0.275 AU) and is somewhat larger than expected from embryo ejection
models (R_out=20-40 AU vs. R_out<10-20 AU).Comment: The Astrophysical Journal, in pres
Effect of Electrically Mediated Intratumor and Intramuscular Delivery of a Plasmid Encoding IFN Ī± on Visible B16 Mouse Melanomas
Interferon Ī± may be used as a single agent therapy for metastatic malignant melanoma or as an adjuvant to chemotherapy. Delivery of interferon Ī± by gene therapy offers an alternative to recombinant protein therapy. Electrically mediated delivery enhances plasmid expression in a number of tissues, for instance skin, liver, muscle and tumors including melanomas. Here we compare the effect of delivery of a plasmid encoding mouse interferon Ī± on growth of visible B16 mouse melanomas following electrically mediated delivery to muscle or directly to the tumor. Intratumoral delivery of interferon Ī± plasmid not only slows melanoma growth, but induces complete, long term, regression. This effect was not observed after intramuscular delivery
New Eruptive YSOs from SPICY and WISE
Ā© Published under Creative Commons license CC BY-SA 4.0.This work presents four high-amplitude variable YSOs (ā3 mag at near-or mid-IR wavelengths) arising from the SPICY catalog. Three outbursts show a duration that is longer than 1 year, and are still ongoing. And additional YSO brightened over the last two epochs of NEOWISE observations and the duration of the outburst is thus unclear. Analysis of the spectra of the four sources confirms them as new members of the eruptive variable class. We find two YSOs that can be firmly classified as bona fide FUors and one object that falls in the V1647 Ori-like class. Given the uncertainty in the duration of its outburst, an additional YSO can only be classified as a candidate FUor. Continued monitoring and follow-up of these particular sources is important to better understand the accretion process of YSOs.Peer reviewe
Diurnal Variations in Vascular Endothelial Vasodilation Are Influenced by Chronotype in Healthy Humans
Introduction: The time of day when cardiovascular events are most likely to occur is thought to be aligned with the circadian rhythm of physiological variables. Chronotype has been shown to influence the time of day when cardiovascular events happen, with early chronotypes reported to be more susceptible in the morning and late chronotypes in the evening. However, no studies have investigated the influence of chronotype on physiological variables responsible for cardiovascular regulation in healthy individuals. Methods: 312 individuals completed the Munich ChronoType Questionnaire to assess chronotype. Twenty participants were randomly selected to continue into the main study. In a repeated-measures experiment, participants were tested between 08:00 and 10:00 h and again between 18:00 and 20:00 h. Measurements of mean arterial pressure, heart rate and vascular endothelial vasodilation via flow-mediated dilatation (FMD) were obtained at each session. Results: Individual diurnal differences in mean arterial pressure and heart rate show no significant relationship with chronotype. Diurnal differences in FMD showed a significant correlation (p = 0.010), driven by a clear significant relationship in the evening and not the morning (p < 0.001). Conclusion: These preliminary data indicate that chronotype influences the diurnal variation of endothelial vasodilation measured using flow-mediated dilatation. Furthermore, we show that the influence of chronotype is much stronger in the evening, highlighting an increased susceptibility for later types. These findings are consistent with the diurnal rhythm in cardiovascular events and uncover potential mechanisms of local mediators that may underpin the influence of chronotype in the onset of these events
New Eruptive YSOs from SPICY and WISE
This work presents four high-amplitude variable YSOs ( 3 mag at near-
or mid-IR wavelengths) arising from the SPICY catalog. Three outbursts show a
duration that is longer than 1 year, and are still ongoing. And additional YSO
brightened over the last two epochs of NEOWISE observations and the duration of
the outburst is thus unclear. Analysis of the spectra of the four sources
confirms them as new members of the eruptive variable class. We find two YSOs
that can be firmly classified as bona fide FUors and one object that falls in
the V1647 Ori-like class. Given the uncertainty in the duration of its
outburst, an additional YSO can only be classified as a candidate FUor.
Continued monitoring and follow-up of these particular sources is important to
better understand the accretion process of YSOs.Comment: 10 pages, 10 figures, Accepted for publication at the Journal of the
Korean Astronomical Societ
Impact of gender on the decision to participate in a clinical trial: a cross-sectional study
Background
In order for Informed Consent to be ethical and valid each clinical trial participant must be able to make a voluntary decision to participate, free from pressure or coercion. Nonetheless, many factors may influence the decision reached, and such influences may be different for male and female volunteers. Being aware of these differences may help researches develop better processes for obtaining consent that safeguard the right of autonomy for all participants. The goal of this study was to evaluate potential gender-based differences in the factors influencing clinical trial participation. Methods
This cross-sectional study was conducted in the Northeast region of Minas Gerais, Brazil, in October 2011. A structured questionnaire was administered to 143 volunteers (48 male, 95 female) screened for participation in a clinical study of an investigational functional food with potential anthelminthic properties. Answers regarding their decision to participate in the study were compared, by gender, using chi-square and Mann Whitney tests. Odds ratios (OR) was used to measure association. Results
A majority of subjects (58% of males, 59% of females) listed the desire to collaborate with the development of a product against parasitic worms as their main reason for participation. Females were significantly more likely to report a decision influenced by friends, family, or researchers (OR 3.14, 3.45, and 3.46 respectively, pā\u3cā0.005). Females were also significantly more likely to report a decision influenced by general altruistic considerations (OR 8.45, pā\u3cā0.005). There was no difference, by gender, in the report of decisions influenced by informational meetings, understanding of the disease, or the availability of medical treatments or exams. There was also no difference in knowledge of the rights of research participants. Conclusion
Study results indicate that there is a strong difference between male and female participants regarding social influences on the decision to participate in clinical research. Further research into the impact this may have on autonomy is warranted
Multilocus sequence typing (MLST) analysis of Vibrio cholerae O1 El Tor isolates from Mozambique that harbour the classical CTX prophage.
Vibrio cholerae O1 isolates belonging to the Ogawa serotype, El Tor biotype, harbouring the classical CTX prophage were first isolated in Mozambique in 2004. Multilocus sequence typing (MLST) analysis using nine genetic loci showed that the Mozambique isolates have the same sequence type (ST) as O1 El Tor N16961, a representative of the current seventh cholera pandemic. Analysis of the CTX prophage in the Mozambique isolates indicated that there is one type of rstR in these isolates: the classical CTX prophage. It was also found that the ctxB-rstR-rstA-rstB-phs-cep fragment was PCR-amplified from these isolates, which indicates the presence of a tandem repeat of the classical CTX prophage in the genome of the Mozambique isolates. The possible origin of these isolates and the presence of the tandem repeat of the classical prophage in them implicate the presence of the classical CTX phage
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