1,225 research outputs found
Cervical Cancer in Cameroon: A Three Pronged Approach to Increase Awareness, Vaccination, Screening and Treatment
Problem: Cameroon has a disproportionately high burden of cervical cancer due to low awareness that the disease is preventable with prophylactic vaccines, lack of screening and treatment of pre-cancerous lesions, and high prevalence of human immunodeficiency virus (HIV). Between 2007-2013, the Cameroon Baptist Convention Health Services (CBCHS) devised three programs to: (1) increase awareness about cervical cancer; (2) immunize girls aged 9-13 years against human papilloma virus (HPV); and (3) conduct cervical cancer screening and treatment.
Approaches: In collaboration with clinicians and researchers at University of Massachusetts and Northeastern University, CBCHS conducted education programs about HPV vaccine and cervical cancer for parents, adolescents, health care workers, and community members. The HPV vaccination demonstration project was implemented in three settings: schools, healthcare facilities, and in communities. CBCHS conducted cervical cancer screening in six sites using a “see and treat approach”.
Findings: Following approval by the Ministry of Health, CBCHS nurses educated girls, parents, and communities about HPV, cervical cancer, and HPV vaccine through multimedia coverage. A total of 6,851, 6,517 and 5,876 girls were immunized with first, second and third doses, respectively. Achieving an 84.6% 3-dose completion rate. Since 2007, 30,617 women have been screened with visual inspection with acetic acid and digital cervicography. Women with precancerous lesions were treated with cryotherapy or loop electrical excision procedure. Lesions suspicious for cancer were biopsied for histology. Of those screened, 3,015 (10%) self reported HIV-positivity, 19,837 (64%) were HIV-negative, and the HIV status of the remaining women was unreported (25%). The percentage of HIV infected women diagnosed with cancer was consistently higher than the percentage of HIV uninfected women diagnosed with cancer.
Lessons Learned: The project demonstrated that, with adequate education of stakeholders, HPV vaccination and cervical cancer screening programs are acceptable and feasible methods to improve cervical cancer outcomes in Cameroon
Early-type stars observed in the ESO UVES Paranal Observatory Project - V. Time-variable interstellar absorption
The structure and properties of the diffuse interstellar medium (ISM) on
small scales, sub-au to 1 pc, are poorly understood. We compare interstellar
absorption-lines, observed towards a selection of O- and B-type stars at two or
more epochs, to search for variations over time caused by the transverse motion
of each star combined with changes in the structure in the foreground ISM. Two
sets of data were used: 83 VLT- UVES spectra with approximately 6 yr between
epochs and 21 McDonald observatory 2.7m telescope echelle spectra with 6 - 20
yr between epochs, over a range of scales from 0 - 360 au. The interstellar
absorption-lines observed at the two epochs were subtracted and searched for
any residuals due to changes in the foreground ISM. Of the 104 sightlines
investigated with typically five or more components in Na I D, possible
temporal variation was identified in five UVES spectra (six components), in Ca
II, Ca I and/or Na I absorption-lines. The variations detected range from 7\%
to a factor of 3.6 in column density. No variation was found in any other
interstellar species. Most sightlines show no variation, with 3{\sigma} upper
limits to changes of the order 0.1 - 0.3 dex in Ca II and Na I. These
variations observed imply that fine-scale structure is present in the ISM, but
at the resolution available in this study, is not very common at visible
wavelengths. A determination of the electron densities and lower limits to the
total number density of a sample of the sightlines implies that there is no
striking difference between these parameters in sightlines with, and sightlines
without, varying components.Comment: 19 pages, 11 figures, accepted for publication in MNRA
Observation of interstellar lithium in the low-metallicity Small Magellanic Cloud
The primordial abundances of light elements produced in the standard theory
of Big Bang nucleosynthesis (BBN) depend only on the cosmic ratio of baryons to
photons, a quantity inferred from observations of the microwave background. The
predicted primordial 7Li abundance is four times that measured in the
atmospheres of Galactic halo stars. This discrepancy could be caused by
modification of surface lithium abundances during the stars' lifetimes or by
physics beyond the Standard Model that affects early nucleosynthesis. The
lithium abundance of low-metallicity gas provides an alternative constraint on
the primordial abundance and cosmic evolution of lithium that is not
susceptible to the in situ modifications that may affect stellar atmospheres.
Here we report observations of interstellar 7Li in the low-metallicity gas of
the Small Magellanic Cloud, a nearby galaxy with a quarter the Sun's
metallicity. The present-day 7Li abundance of the Small Magellanic Cloud is
nearly equal to the BBN predictions, severely constraining the amount of
possible subsequent enrichment of the gas by stellar and cosmic-ray
nucleosynthesis. Our measurements can be reconciled with standard BBN with an
extremely fine-tuned depletion of stellar Li with metallicity. They are also
consistent with non-standard BBN.Comment: Published in Nature. Includes main text and Supplementary
Information. Replaced with final title and abstrac
Key signal contributions in photothermal deflection spectroscopy
We report on key signal contributions in photothermal deflection spectroscopy
(PDS) of semiconductors at photon energies below the bandgap energy and show
how to extract the actual absorption properties from the measurement data. To
this end, we establish a rigorous computation scheme for the deflection signal
including semi-analytic raytracing to analyze the underlying physical effects.
The computation takes into account linear and nonlinear absorption processes
affecting the refractive index and thus leading to a deflection of the probe
beam. We find that beside the linear mirage effect, nonlinear absorption
mechanisms make a substantial contribution to the signal for strongly focussed
pump beams and sample materials with high two-photon absorption coefficients.
For example, the measured quadratic absorption contribution exceeds 5% at a
pump beam intensity of about in Si and at
in GaAs. In addition, our method also
includes thermal expansion effects as well as spatial gradients of the
attenuation properties. We demonstrate that these effects result in an
additional deflection contribution which substantially depends on the distance
of the photodetector from the readout point. This distance dependent
contribution enhances the surface related PDS signal up to two orders of
magnitude and may be misinterpreted as surface absorption if not corrected in
the analysis of the measurement data. We verify these findings by PDS
measurements on crystalline silicon at a wavelength of 1550 nm and provide
guidelines how to extract the actual attenuation coefficient from the PDS
signal.Comment: 10 pages, 16 figures, submitted to Journal of Applied Physiv
Abundances and Physical Conditions in the Interstellar Gas toward HD 192 639
We present a study of the abundances and physical conditions in the
interstellar gas toward the heavily reddened star HD 192639 [E_(B-V) = 0.64],
based on analysis of FUSE and HST/STIS spectra covering the range from 912 to
1361 A. This work constitutes a survey of the analyses that can be performed to
study the interstellar gas when combining data from different instruments.
Low-velocity (-18 to -8 km/s) components are seen primarily for various neutral
and singly ionized species such as C I, O I, S I, Mg II, Cl I, Cl II, Mn II, Fe
II and Cu II. Numerous lines of H2 are present in the FUSE spectra, with a
kinetic temperature for the lowest rotational levels T_(01) = (90 +/- 10) K.
Analysis of the C I fine-structure excitation implies an average local density
of hydrogen n_H = (16 +/- 3) cm^-3. The average electron density, derived from
five neutral/first ion pairs under the assumption of photoionization
equilibrium, is n_e = (0.11 +/- 0.02) cm^-3. The relatively complex component
structure seen in high-resolution spectra of K I and Na I, the relatively low
average density, and the measured depletions all suggest that the line of sight
contains a number of diffuse clouds, rather than a single dense, translucent
cloud. Comparisons of the fractions of Cl in Cl I and of hydrogen in molecular
form suggest a higher molecular fraction, in the region(s) where H2 is present,
than that derived considering the average line of sight. In general, such
comparisons may allow the identification and characterization of translucent
portions of such complex lines of sight. The combined data also show
high-velocity components near -80 km/s for various species which appear to be
predominantly ionized, and may be due to a radiative shock. A brief overview of
the conditions in this gas will be given.Comment: 37 pages, accepted for publication in Ap
Diffuse Atomic and Molecular Gas near IC443
We present an analysis of results on absorption from Ca II, Ca I, K I, and
the molecules CH+, CH, C2, and CN that probes gas interacting with the
supernova remnant IC443. The eleven directions sample material across the
visible nebula and beyond its eastern edge. Most of the neutral material,
including the diatomic molecules, is associated with the ambient cloud detected
via H I and CO emission. Analysis of excitation and chemistry yields gas
densities that are typical of diffuse molecular gas. The low density gas probed
by Ca II extends over a large range in velocities, from -120 to +80 km/s in the
most extreme cases. This gas is distributed among several velocity components,
unlike the situation for the shocked molecular clumps, whose emission occurs
over much the same range but as very broad features. The extent of the
high-velocity absorption suggests a shock velocity of 100 km/s for the
expanding nebula.Comment: To be published in Ap
The Evolution of Damped Lyman-alpha Absorbers: Metallicities and Star Formation Rates
The damped Lyman-alpha (DLA) and sub-DLA quasar absorption lines provide
powerful probes of the evolution of metals, gas, and stars in galaxies. One
major obstacle in trying to understand the evolution of DLAs and sub-DLAs has
been the small number of metallicity measurements at z < 1.5, an epoch spanning
\~70 % of the cosmic history. In recent surveys with the Hubble Space Telescope
and Multiple Mirror Telescope, we have doubled the DLA Zn sample at z < 1.5.
Combining our results with those at higher redshifts from the literature, we
find that the global mean metallicity of DLAs does not rise to the solar value
at low redshifts. These surprising results appear to contradict the near-solar
mean metallicity observed for nearby (z ~ 0) galaxies and the predictions of
cosmic chemical evolution models based on the global star formation history.
Finally, we discuss direct constraints on the star formation rates (SFRs) in
the absorber galaxies from our deep Fabry-Perot Ly-alpha imaging study and
other emission-line studies in the literature. A large fraction of the observed
heavy-element quasar absorbers at 0 < z < 3.4 appear to have SFRs substantially
below the global mean SFR, consistent with the low metallicities observed in
the spectroscopic studies.Comment: 6 pages,3 figures, To appear in "Probing Galaxies through Quasar
Absorption Lines", Proceedings IAU Colloquium 199, 2005, Eds. P. R. Williams,
C. Shu, and B. Menar
Manipulating Wild and Tamed Phytobiomes: Challenges and Opportunities
This white paper presents a series of perspectives on current and future phytobiome management, discussed at the Wild and Tamed Phytobiomes Symposium in University Park, PA, USA, in June 2018. To enhance plant productivity and health, and to translate lab- and greenhouse-based phytobiome research to field applications, the academic community and end-users need to address a variety of scientific, practical, and social challenges. Prior discussion of phytobiomes has focused heavily on plant-associated bacterial and fungal assemblages, but the phytobiomes concept covers all factors that influence plant function. Here we discuss various management considerations, including abiotic conditions (e.g. soil, nutrient applications), microorganisms (e.g. bacterial and fungal assemblages, bacterial and fungal inoculants, viruses), macroorganisms (e.g. arthropods, plant genetics), and societal factors (e.g. communication approaches, technology diffusion). An important near-term goal for this field should be to estimate the potential relative contribution of different components of the phytobiome to plant health, as well as the potential and risk of modifying each in the near-future
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