259 research outputs found
Epidemiology of colorectal cancer.
Colorectal cancer is currently the third deadliest cancer in the United States and will claim an estimated 49,190 U.S. lives in 2016. The purpose of this review is to summarize our current understanding of this disease, based on nationally published statistics and information presented in peer-reviewed journal articles. Specifically, this review will cover the following topics: descriptive epidemiology (including time and disease trends both in the United States and abroad), risk factors (environmental, genetic, and gene-environment interactions), screening, prevention and control, and treatment. Landmark discoveries in colorectal cancer risk factor research will also be presented. Based on the information reviewed for this report, we suggest that future U.S. public health efforts aim to increase colorectal cancer screening among African American communities, and that future worldwide colorectal cancer epidemiology studies should focus on researching nutrient-gene interactions towards the goal of improving personalized treatment and prevention strategies
Asymmetric Dark Matter May Alter the Evolution of Low-mass Stars and Brown Dwarfs
We study energy transport by asymmetric dark matter in the interiors of very
low-mass stars and brown dwarfs. Our motivation is to explore astrophysical
signatures of asymmetric dark matter, which otherwise may not be amenable to
conventional indirect dark matter searches. In viable models, the additional
cooling of very-low mass stellar cores can alter stellar properties. Asymmetric
dark matter with mass 4 < Mx/GeV < 10 and a spin-dependent (spin-independent)
cross sections of sigma \sim 10^{-37} cm^2 (sigma \sim 10^{-40} cm^2) can
increase the minimum mass of main sequence hydrogen burning, partly determining
whether or not the object is a star at all. Similar dark matter candidates
reduce the luminosities of low-mass stars and accelerate the cooling of brown
dwarfs. Such light dark matter is of particular interest given results from the
DAMA, CoGeNT, and CRESST dark matter searches. We discuss possibilities for
observing dark matter effects in stars in the solar neighborhood, globular
clusters, and, of particular promise, local dwarf galaxies, among other
environments, as well as exploiting these effects to constrain dark matter
properties.Comment: 6 Pages, 4 Figures. Accepted for Publication in Phys. Rev. D Rapid
Communication
Intake of methyl-related nutrients and risk of pancreatic cancer in a population-based case-control study in Minnesota
BACKGROUND/OBJECTIVES:
Folate, vitamin B6, vitamin B12, and methionine are involved in DNA synthesis and methylation and thus may modulate pancreatic cancer risk. We investigated these associations in a population-based case-control study conducted in 1994-1998.
SUBJECTS/METHODS:
Cases (n = 150) were identified from all hospitals in the metropolitan areas of the Twin Cities and the Mayo Clinic, Minnesota. Controls (n = 459) were selected randomly from the general population and were frequency matched to cases by age, sex, and race. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for risk of pancreatic cancer in relation to intake of nutrients considered.
RESULTS:
Dietary intake of folate was associated with a reduced pancreatic cancer risk [OR (95% CI) for quartile (Q) 4 vs. Q1: 0.31 (0.12-0.78)]. A composite score (range from 2 to 8), reflecting combined dietary intake of folate and vitamin B6, was also inversely associated with pancreatic cancer risk [OR (95% CI) for Q4 vs. Q1: 0.24 (0.08-0.70)]. Null associations were found for intake of vitamin B12 and methionine.
CONCLUSIONS:
Dietary folate intake was associated with a reduced pancreatic cancer risk, and this association became stronger when dietary intake of folate and vitamin B6 was combined in analysis
Exploratory Pollen Analysis of the Ditch of the 1665 Turf Fort, Jamestown, Virginia
Pollen analysis of subsoil, slopewash, episodic fill, plowzone, and archaeological backdirt deposits in a core from a ditch associated with the 1665 Turf (earthwork) Fort at Jamestown, Virginia, record bare, slightly weedy local conditions around 17th-century artisan dwellings on the Jamestown waterfront and register the Virginia forest in the background before construction of the fort. Goosefoot dominated the earthwork slope; close relatives of the goldenrods were initially the most prominent plants in the open-ditch period. Pollen percolation rates adjusted for plowing and applied to ragweed-type (Ambrosia-type) percentages suggest that cultivation over the ditch began ca. 1729. Cultural matrix depostition, slopewash, and pollen percolation were crticial to the preservation of this record, and serve to emphasize the importance of evaluating pollen record formation processes in cultural landscape studies
L-dwarf variability: I-band observations
We report on the results of an I-band photometric variability survey of
eighteen L dwarfs. We find that seven exhibit statistically significant
variations above the 95.4% confidence level with root-mean-square scatter
(including photometric errors) between 0.010 and 0.083 mag. Another five
targets have variability probabilities ~80%, suggesting that these are likely
variable objects. Three of the variable objects display significant peaks in a
CLEAN periodogram that are several times higher than the noise. The period for
2MASS 0345+25 is clearly not intrinsic to the object and can be dismissed. The
periods found for 2MASS 0746+20AB and 2MASS 1300+19 are unique but longer than
those periods likely from rotation velocity measurements and they do not
represent periodic behavior in the light curve that persists through the entire
data set. These observations suggest that we are not observing the rotation
modulation of a long-lived albedo feature. Instead, rapid evolution of
atmospheric features is likely causing the non-periodic variability. The
remaining variable objects show no prominent features in their light curves,
suggesting even more rapid evolution of atmospheric features. We argue against
the existence of magnetic spots in these atmospheres and favor the idea that
non-uniform condensate coverage is responsible for these variations. The
magnetic Reynolds number in the atmosphere of L dwarfs is too small to support
the formation of magnetic spots. In contrast, silicate and iron clouds are
expected to form in the photospheres of L dwarfs. Inhomogeneities in such cloud
decks and the evolution of the inhomogeneities can plausibly produce the
observed photometric variations.Comment: 42 pages, 14 figures, minor corrections for typos and Figure 12, to
appear in ApJ, v577, September 20, 200
An L Band Spectrum of the Coldest Brown Dwarf
The coldest brown dwarf, WISE 0855, is the closest known planetary-mass,
free-floating object and has a temperature nearly as cold as the solar system
gas giants. Like Jupiter, it is predicted to have an atmosphere rich in
methane, water, and ammonia, with clouds of volatile ices. WISE 0855 is faint
at near-infrared wavelengths and emits almost all its energy in the
mid-infrared. Skemer et al. 2016 presented a spectrum of WISE 0855 from 4.5-5.1
micron (M band), revealing water vapor features. Here, we present a spectrum of
WISE 0855 in L band, from 3.4-4.14 micron. We present a set of atmosphere
models that include a range of compositions (metallicities and C/O ratios) and
water ice clouds. Methane absorption is clearly present in the spectrum. The
mid-infrared color can be better matched with a methane abundance that is
depleted relative to solar abundance. We find that there is evidence for water
ice clouds in the M band spectrum, and we find a lack of phosphine spectral
features in both the L and M band spectra. We suggest that a deep continuum
opacity source may be obscuring the near-infrared flux, possibly a deep
phosphorous-bearing cloud, ammonium dihyrogen phosphate. Observations of WISE
0855 provide critical constraints for cold planetary atmospheres, bridging the
temperature range between the long-studied solar system planets and accessible
exoplanets. JWST will soon revolutionize our understanding of cold brown dwarfs
with high-precision spectroscopy across the infrared, allowing us to study
their compositions and cloud properties, and to infer their atmospheric
dynamics and formation processes.Comment: 19 pages, 21 figures. Accepted for publication in Ap
Precipitating Condensation Clouds in Substellar Atmospheres
We present a method to calculate vertical profiles of particle size
distributions in condensation clouds of giant planets and brown dwarfs. The
method assumes a balance between turbulent diffusion and sedimentation in
horizontally uniform cloud decks. Calculations for the Jovian ammonia cloud are
compared with results from previous methods. An adjustable parameter describing
the efficiency of sedimentation allows the new model to span the range of
predictions made by previous models. Calculations for the Jovian ammonia cloud
are consistent with observations. Example calculations are provided for water,
silicate, and iron clouds on brown dwarfs and on a cool extrasolar giant
planet. We find that precipitating cloud decks naturally account for the
characteristic trends seen in the spectra and colors of L- and T-type ultracool
dwarfs.Comment: 33 pages including 7 figures; AASTex; Accepted for publication in
Astrophysical Journal, tentatively scheduled for v556 n1 July 20, 2001 .
Plotting error in Fig 5 corrected; slight modification to Fig 5 dicussion in
tex
Directly Imaged L-T Transition Exoplanets in the Mid-Infrared
Gas-giant planets emit a large fraction of their light in the mid-infrared
(3m), where photometry and spectroscopy are critical to our
understanding of the bulk properties of extrasolar planets. Of particular
importance are the L and M-band atmospheric windows (3-5m), which are the
longest wavelengths currently accessible to ground-based, high-contrast
imagers. We present binocular LBT AO images of the HR 8799 planetary system in
six narrow-band filters from 3-4m, and a Magellan AO image of the 2M1207
planetary system in a broader 3.3m band. These systems encompass the five
known exoplanets with luminosities consistent with LT transition
brown dwarfs. Our results show that the exoplanets are brighter and have
shallower spectral slopes than equivalent temperature brown dwarfs in a
wavelength range that contains the methane fundamental absorption feature
(spanned by the narrowband filters and encompassed by the broader 3.3m
filter). For 2M1207 b, we find that thick clouds and non-equilibrium chemistry
caused by vertical mixing can explain the object's appearance. For the HR 8799
planets, we present new models that suggest the atmospheres must have patchy
clouds, along with non-equilibrium chemistry. Together, the presence of a
heterogeneous surface and vertical mixing presents a picture of dynamic
planetary atmospheres in which both horizontal and vertical motions influence
the chemical and condensate profiles.Comment: Accepted to Ap
The Relationship between Mammography and a Multi-factor Behavioral Index
Objective: In this study, we sought to determine whether a multi-factor behavioral index predicts mammography screening in US women. Methods: Women aged 50-75 years were enrolled in an intervention study and provided their vegetable intake, physical activity (PA), smoking, body mass index (BMI), and alcohol intake. Each factor was scored from 0 (least healthy) to 4 (most healthy) then summed to form a multi-factor behavioral index (ranging from 0-20). Selfreport and medical records were used to determine mammography screening 6-months postintervention. Logistic regression was used to estimate multivariable-adjusted odds ratios (OR) and 95% confidence intervals (CI) for the association with 6-month mammography. Results: The mean score for the multi-factor index was 11.8. An increased index score marginally predicted mammography adherence [OR = 1.05 (0.99-1.11)], with a stronger association among women receiving a doctor’s recommendation for mammography [OR = 1.12 (1.04-1.20)]. Of the independent behavioral factors, high PA [OR = 1.13 (0.99-1.30), p = .075] and low BMI [OR = 1.25 (1.04-1.51), p = .017] were marginal and significant predictors of mammography, respectively. Conclusion: Women who engaged in a healthier behavioral lifestyle were more likely to utilize mammography screening, especially if they received a physician recommendation. Physicians should encourage mammography screening as part of a healthy behavioral lifestyle
Realistic expectations for the treatment of FMGP residuals by chemical oxidants
The final publication is available at Elsevier via https://dx.doi.org/10.1016/j.jconhyd.2018.08.007 © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license https://creativecommons.org/licenses/by-nc-nd/4.0/Methods to remediate soil and groundwater contamination at former manufactured gas plant (FMGP) sites are scarce. The objective of this study was to investigate the ability of two chemical oxidants (persulfate and permanganate) to degrade FMGP residuals in a dynamic system representative of in situ conditions. A series of physical model trials supported by aqueous and slurry batch experiments using impacted sediments collected from a FMGP site were conducted. To explore treatment expectations a screening model constrained by the experimental data was employed. The results from the aqueous experiments showed that dissolved components (except for benzene) were readily degraded by persulfate or permanganate. In the well-mixed slurry systems, when contact with the oxidant was achieved, 95%, 45% and 30% of the initial mass quantified was degraded by permanganate, unactivated persulfate, and alkaline activated persulfate, respectively. In stark contrast, the total mass removed in the physical model trials was negligible for both permanganate and persulfate irrespective of the bleb or lense architecture used. Hence the net benefit of flushing 6 pore volumes of permanganate or persulfate at a concentration of 30 g/L under the physical model operating conditions was minimal. To achieve a substantial degradation of mass within the treatment system (>40%), results from the screening model indicated that the hydraulic resident time would need to be >10 days and the average lumped mass transfer coefficient increased by two orders-of-magnitude. Results from long-term (5 years) simulations showed that the dissolved concentrations of organic compounds are reduced temporarily as a result of the presence of permanganate but then rebound to a profile that is essentially coincident with a no-treatment scenario following exposure to permanganate. Neither a lower velocity nor higher permanganate dosing affected the long-term behavior of the dissolved phase concentrations; however, increasing the mass transfer rate coefficient had an impact. The findings from this investigation indicate that the efficiency of permanganate or persulfate to treat for FMGP residuals is mass transfer limited.TECO Peoples Gas, Tampa FLNatural Sciences and Engineering Research Council (NSERC) of Canada Collaborative Research and Development Gran
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