2,221 research outputs found
Reduction of computer usage costs in predicting unsteady aerodynamic loadings caused by control surface motions: Computer program description
A digital computer program was developed to calculate unsteady loadings caused by motions of lifting surfaces with leading edge and trailing edge controls based on the subsonic kernel function approach. The pressure singularities at hinge line and side edges were extracted analytically as a preliminary step to solving the integral equation of collocation. The program calculates generalized aerodynamic forces for user supplied deflection modes. Optional intermediate output includes pressure at an array of points, and sectional generalized forces. From one to six controls on the half span can be accomodated
The Discovery and Broad-band Follow-up of the Transient Afterglow of GRB 980703
We report on the discovery of the radio, infrared and optical transient
coincident with an X-ray transient proposed to be the afterglow of GRB 980703.
At later times when the transient has faded below detection, we see an
underlying galaxy with R=22.6; this galaxy is the brightest host galaxy (by
nearly 2 magnitudes) of any cosmological GRB thus far. In keeping with an
established trend, the GRB is not significantly offset from the host galaxy.
Interpreting the multi-wavelength data in the framework of the popular fireball
model requires that the synchrotron cooling break was between the optical and
X-ray bands on July 8.5 UT and that the intrinsic extinction of the transient
is Av=0.9. This is somewhat higher than the extinction for the galaxy as a
whole, as estimated from spectroscopy.Comment: 5 pages, 3 figures, and 2 tables. Submitted to the Astrophysical
Journal Letters on 27 August 199
Factors affecting attitudes toward colorectal cancer screening in the primary care population
BACKGROUND: Colorectal cancer (CRC) is a major cause of death in the United Kingdom. Regular screening could significantly reduce CRC-related morbidity and mortality. However, screening programmes in the United Kingdom have to date seen uptake rates of less than 60%. Attitudes towards screening are the primary factors determining patient uptake. METHODS: A questionnaire was sent to people aged 50-69 years who were registered with general practices in the West Midlands. A total of 11 355 people (53%) completed the questionnaire. Multivariable logistic regression analyses were performed to identify those factors (gender, age, ethnicity, deprivation, number of symptoms, and their duration) that most strongly contributed to negative/positive attitudes in the primary care population. RESULTS: Fourteen percent of respondents had a negative attitude towards screening. Men, older people, and those with Indian ethnic backgrounds were more likely to have negative attitudes toward screening, whereas people with Black-Caribbean ethnic background, people with multiple symptoms and those reporting abdominal pain, bleeding, and tiredness were more likely to have a positive attitude. CONCLUSION: Culturally relevant screening strategies should aim to increase knowledge of the symptoms and signs related to bowel cancer among South Asian ethnic groups in the United Kingdom. It is also important to find ways to increase the acceptability of screening among asymptomatic patients
Oncolog, Volume 36, Issue 01, January-March 1991
Decision making in critical illness: Who knows best? Successful Hodgkin\u27s disease treatment can also preserve reproductive function Chromosomes and cancerhttps://openworks.mdanderson.org/oncolog/1033/thumbnail.jp
Lifelongα-tocopherol supplementation increases the median life span of C57BL/6 mice in the cold but has only minor effects on oxidative damage
The effects of dietary antioxidant supplementation on oxidative stress and life span are confused. We maintained C57BL/6 mice at 7 ± 2°C and supplemented their diet with α-tocopherol from 4 months of age. Supplementation significantly increased (p = 0.042) median life span by 15% (785 days, n = 44) relative to unsupplemented controls (682 days, n = 43) and also increased maximum life span (oldest 10%, p = 0.028). No sex or sex by treatment interaction effects were observed on life span, with treatment having no effect on resting or daily metabolic rate. Lymphocyte and hepatocyte oxidative DNA damage and hepatic lipid peroxidation were unaffected by supplementation, but hepatic oxidative DNA damage increased with age. Using a cDNA macroarray, genes associated with xenobiotic metabolism were significantly upregulated in the livers of female mice at 6 months of age (2 months supplementation). At 22 months of age (18 months supplementation) this response had largely abated, but various genes linked to the p21 signaling pathway were upregulated at this time. We suggest that α-tocopherol may initially be metabolized as a xenobiotic, potentially explaining why previous studies observe a life span extension generally when lifelong supplementation is initiated early in life. The absence of any significant effect on oxidative damage suggests that the life span extension observed was not mediated via any antioxidant properties of α-tocopherol. We propose that the life span extension observed following α-tocopherol supplementation may be mediated via upregulation of cytochrome p450 genes after 2 months of supplementation and/or upregulation of p21 signaling genes after 18 months of supplementation. However, these signaling pathways now require further investigation to establish their exact role in life span extension following α-tocopherol supplementation
SiO Outflow Signatures Toward Massive Young Stellar Objects with Linearly Distributed Methanol Masers
Methanol masers are often found in linear distributions, and it has been
hypothesized that these masers are tracing circumstellar accretion disks around
young massive stars. However, recent observations in H2 emission have shown
what appear to be outflows at similar angles to the maser distribution angles,
not perpendicular as expected in the maser-disk scenario. The main motivation
behind the observations presented here is to determine from the presence and
morphology of an independent outflow tracer, namely SiO, if there are indeed
outflows present in these regions and if they are consistent or inconsistent
with the maser-disk hypothesis. For ten sources with H2 emission we obtained
JCMT single dish SiO (6-5) observations to search for the presence of this
outflow indicator. We followed up those observations with ATCA interferometric
mapping of the SiO emission in the (2-1) line in six sources. The JCMT
observations yielded a detection in the SiO (6-5) line in nine of the ten
sources. All of the sources with bright SiO lines display broad line wings
indicative of outflow. A subset of the sources observed with the JCMT have
methanol maser velocities significantly offset from their parent cloud
velocities, supporting the idea that the masers in these sources are likely not
associated with circumstellar disks. The ATCA maps of the SiO emission show
five of the six sources do indeed have SiO outflows. The spatial orientations
of the outflows are not consistent with the methanol masers delineating disk
orientations. Overall, the observations presented here seem to provide further
evidence against the hypothesis that linearly distributed methanol masers
generally trace the orientations of circumstellar disks around massive young
stars.Comment: Accepted for publication in A&A; 36 pages, 8 figures; a version with
higher quality figures can be found at http://www.jim-debuizer.net/researc
Direct Observations of the Ionizing Star in the UC HII Region G29.96-0.02: A Strong Constraint on the Stellar Birth Line for Massive Stars
We have observed the ultracompact HII region G29.96-0.02 in the near infrared
J, H, and K bands and in the Br-gamma line. By comparison with radio
observations, we determine that the extinction to the nebula is AK = 2.14 with
a 3 sigma uncertainty of 0.25. We identify the ionizing star and determine its
intrinsic K magnitude. The star does not have an infrared excess and so appears
to be no longer accreting. The K magnitude and the bolometric luminosity allow
us to place limits on the location of the ionizing star in the HR diagram. The
3 sigma upper limit on the effective temperature of the ionizing star is 42500
K. We favor a luminosity appropriate for star with a mass in excess of about 60
solar masses. The limit on the temperature and luminosity exclude stars on the
ZAMS and stars within 10^6 yr of the ZAMS. Since the age of the UC HII region
is estimated to be only about 10^5 yr, we suggest that this is direct evidence
that the stellar birth line for massive stars at twice solar metallicity must
be significantly redder than the ZAMS.Comment: 42 pages; LaTex; 11 Postscript figures; accepted for publication in
Ap
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