644 research outputs found
SPITZER SAGE Observations of Large Magellanic Cloud Planetary Nebulae
We present IRAC and MIPS images and photometry of a sample of previously
known planetary nebulae (PNe) from the SAGE survey of the Large Magellanic
Cloud (LMC) performed with the Spitzer Space Telescope. Of the 233 known PNe in
the survey field, 185 objects were detected in at least two of the IRAC bands,
and 161 detected in the MIPS 24 micron images. Color-color and color-magnitude
diagrams are presented using several combinations of IRAC, MIPS, and 2MASS
magnitudes. The location of an individual PN in the color-color diagrams is
seen to depend on the relative contributions of the spectral components which
include molecular hydrogen, polycyclic aromatic hydrocarbons (PAHs), infrared
forbidden line emission from the ionized gas, warm dust continuum, and emission
directly from the central star. The sample of LMC PNe is compared to a number
of Galactic PNe and found to not significantly differ in their position in
color-color space. We also explore the potential value of IR PNe luminosity
functions (LFs) in the LMC. IRAC LFs appear to follow the same functional form
as the well-established [O III] LFs although there are several PNe with
observed IR magnitudes brighter than the cut-offs in these LFs.Comment: 18 pages, 10 figures, 3 tables, to be published in the Astronomical
Journal. Additional online data available at
http://www.cfa.harvard.edu/irac/publications
The active living gender's gap challenge: 2013-2017 Eurobarometers physical inactivity data show constant higher prevalence in women with no progress towards global reduction goals
BACKGROUND: The World Health Organization (WHO) considers physical inactivity (PIA) as a critical noncommunicable factor for disease and mortality, affecting more women than men. In 2013, the WHO set a 10% reduction of the PIA prevalence, with the goal to be reached by 2025. Changes in the 2013-2017 period of physical inactivity prevalence in the 28 European Union (EU) countries were evaluated to track the progress in achieving WHO 2025 target. METHODS: In 2013 and 2017 EU Special Eurobarometers, the physical activity levels reported by the International Physical Activity Questionnaire of 53,607 adults were analyzed. Data were considered as a whole sample and country-by-country. A χ2 test was used to analyze the physical inactivity prevalence (%) between countries, analyzing women and men together and separately. Additionally, PIA prevalence was analyzed between years (2013-2017) for the overall EU sample and within-country using a Z-Score for two population proportions. RESULTS: The PIA prevalence increased between 2013 and 2017 for the overall EU sample (p < 0.001), and for women (p = 0.04) and men (p < 0.001) separately. Data showed a higher PIA prevalence in women versus men during both years (p < 0.001). When separately considering changes in PIA by gender, only Belgium's women and Luxembourg's men showed a reduction in PIA prevalence. Increases in PIA prevalence over time were observed in women from Austria, Croatia, Germany, Lithuania, Malta, Portugal, Romania, and Slovakia and in men from Bulgaria, Croatia, Czechia, Germany, Italy, Lithuania, Portugal, Romania, Slovakia, and Spain. CONCLUSIONS: PIA prevalence showed an overall increase across the EU and for both women and men between 2013 and 2017, with higher rates of PIA reported for women versus men during both years. PIA prevalence was reduced in only Belgium's women and Luxembourg's men. Our data indicate a limited gender-sensible approach while tacking PIA prevalence with no progress reaching global voluntary reductions of PIA for 2025
An Essential Difference between the Flavonoids MonoHER and Quercetin in Their Interplay with the Endogenous Antioxidant Network
Antioxidants can scavenge highly reactive radicals. As a result the antioxidants are converted into oxidation products that might cause damage to vital cellular components. To prevent this damage, the human body possesses an intricate network of antioxidants that pass over the reactivity from one antioxidant to another in a controlled way. The aim of the present study was to investigate how the semi-synthetic flavonoid 7-mono-O-(β-hydroxyethyl)-rutoside (monoHER), a potential protective agent against doxorubicin-induced cardiotoxicity, fits into this antioxidant network. This position was compared with that of the well-known flavonoid quercetin. The present study shows that the oxidation products of both monoHER and quercetin are reactive towards thiol groups of both GSH and proteins. However, in human blood plasma, oxidized quercetin easily reacts with protein thiols, whereas oxidized monoHER does not react with plasma protein thiols. Our results indicate that this can be explained by the presence of ascorbate in plasma; ascorbate is able to reduce oxidized monoHER to the parent compound monoHER before oxidized monoHER can react with thiols. This is a major difference with oxidized quercetin that preferentially reacts with thiols rather than ascorbate. The difference in selectivity between monoHER and quercetin originates from an intrinsic difference in the chemical nature of their oxidation products, which was corroborated by molecular quantum chemical calculations. These findings point towards an essential difference between structurally closely related flavonoids in their interplay with the endogenous antioxidant network. The advantage of monoHER is that it can safely channel the reactivity of radicals into the antioxidant network where the reactivity is completely neutralized
Why did I not prepare for this? The politics of negotiating fieldwork access, identity, and methodology in researching microfinance institutions
It has been increasingly recognized that undertaking qualitative research can pose many challenges for researchers. However, scanty literature focuses directly on the experiences of doctoral research students from developing countries studying in Western Europe and other similar geographic regions, and the challenges of doing fieldwork when they return “back home”. In this article, I use my experiences in the process of undertaking PhD fieldwork on two donor-funded microfinance institutions located in Zambia to demonstrate that doctoral students from specific regions (Africa in particular) undertaking research in their native countries can struggle to manage and make sense of the challenges and identity issues raised in their “familiar” environments. I also present a detailed discussion of how various gatekeepers and participants facilitated access, identity alteration, and the impact of insider–outsider positionality on collected data. It is concluded that organizational “politics” and local context can have significant bearing on power relationships, identities of researchers, and methodological preferences
Mass signature of supernova and neutrinos in SuperKamiokande
The and neutrinos (and their antiparticles) from a
Galactic core-collapse supernova can be observed in a water-\v{C}erenkov
detector by the neutral-current excitation of O. The number of events
expected is several times greater than from neutral-current scattering on
electrons. The observation of this signal would be a strong test that these
neutrinos are produced in core-collapse supernovae, and with the right
characteristics. In this paper, this signal is used as the basis for a
technique of neutrino mass determination from a future Galactic supernova. The
masses of the and neutrinos can either be measured or
limited by their delay relative to the neutrinos. By comparing to
the high-statistics data instead of the theoretical expectation,
much of the model dependence is canceled. Numerical results are presented for a
future supernova at 10 kpc as seen in the SuperKamiokande detector. Under
reasonable assumptions, and in the presence of the expected counting
statistics, and masses down to about 50 eV can be simply
and robustly determined. The signal used here is more sensitive to small
neutrino masses than the signal based on neutrino-electron scattering.Comment: 13 pages including 5 figures, to appear in Phys. Rev. D; second
version has minor corrections and is in two-column for
Chemical Abundances and Dust in Planetary Nebulae in the Galactic Bulge
We present mid-infrared Spitzer spectra of eleven planetary nebulae in the
Galactic Bulge. We derive argon, neon, sulfur, and oxygen abundances for them
using mainly infrared line fluxes combined with some optical line fluxes from
the literature. Due to the high extinction toward the Bulge, the infrared
spectra allow us to determine abundances for certain elements more accurately
that previously possible with optical data alone. Abundances of argon and
sulfur (and in most cases neon and oxygen) in planetary nebulae in the Bulge
give the abundances of the interstellar medium at the time their progenitor
stars formed; thus these abundances give information about the formation and
evolution of the Bulge. The abundances of Bulge planetary nebulae tend to be
slightly higher than those in the Disk on average, but they do not follow the
trend of the Disk planetary nebulae, thus confirming the difference between
Bulge and Disk evolution. Additionally, the Bulge planetary nebulae show
peculiar dust properties compared to the Disk nebulae. Oxygen-rich dust feature
(crystalline silicates) dominate the spectra of all of the Bulge planetary
nebulae; such features are more scarce in Disk nebulae. Additionally,
carbon-rich dust features (polycyclic aromatic hydrocarbons) appear in roughly
half of the Bulge planetary nebulae in our sample, which is interesting in
light of the fact that this dual chemistry is comparatively rare in the Milky
Way as a whole.Comment: 16 pages, 5 figures, accepted to Ap
Caspase-dependent and -independent suppression of apoptosis by monoHER in Doxorubicin treated cells
Doxorubicin (DOX) is an antitumour agent for different types of cancer, but the dose-related cardiotoxicity limits its clinical use. To prevent this side effect we have developed the flavonoid monohydroxyethylrutoside (monoHER), a promising protective agent, which did not interfere with the antitumour activity of DOX. To obtain more insight in the mechanism underlying the selective protective effects of monoHER, we investigated whether monoHER (1 mM) affects DOX-induced apoptosis in neonatal rat cardiac myocytes (NeRCaMs), human endothelial cells (HUVECs) and the ovarian cancer cell lines A2780 and OVCAR-3. DOX-induced cell death was effectively reduced by monoHER in heart, endothelial and A2780 cells. OVCAR-3 cells were highly resistant to DOX-induced apoptosis. Experiments with the caspase-inhibitor zVAD-fmk showed that DOX-induced apoptosis was caspase-dependent in HUVECs and A2780 cells, whereas caspase-independent mechanisms seem to be important in NeRCaMs. MonoHER suppressed DOX-dependent activation of the mitochondrial apoptotic pathway in normal and A2780 cells as illustrated by p53 accumulation and activation of caspase-9 and -3 cleavage. Thus, monoHER acts by suppressing the activation of molecular mechanisms that mediate either caspase-dependent or -independent cell death. In light of the current work and our previous studies, the use of clinically achievable concentrations of monoHER has no influence on the antitumour activity of DOX whereas higher concentrations as used in the present study could influence the antitumour activity of DOX
Investigating potential planetary nebula/cluster pairs
Fundamental parameters characterizing the end-state of intermediate-mass
stars may be constrained by discovering planetary nebulae (PNe) in open
clusters (OCs). Cluster membership may be exploited to establish the distance,
luminosity, age, and physical size for PNe, and the intrinsic luminosity and
mass of its central star. Four potential PN-OC associations were investigated,
to assess the cluster membership for the PNe. Radial velocities were measured
from intermediate-resolution optical spectra, complemented with previous
estimates in the literature. When the radial velocity study supported the PN/OC
association, we analyzed if other parameters (e.g., age, distance, reddening,
central star brightness) were consistent with this conclusion. Our measurements
imply that the PNe VBe3 and HeFa1 are not members of the OCs NGC5999 and
NGC6067, respectively, and likely belong to the background bulge population.
Conversely, consistent radial velocities indicate that NGC2452/NGC2453 could be
associated, but our results are not conclusive and additional observations are
warranted. Finally, we demonstrate that all the available information point to
He2-86 being a young, highly internally obscured PN member of NGC4463. New
near-infrared photometry acquired via the Vista Variables in the Via Lactea ESO
public survey was used in tandem with existing UBV photometry to measure the
distance, reddening, and age of NGC4463, finding d=1.55+-0.10 kpc,
E(B-V)=0.41+-0.02, and tau=65+-10 Myr, respectively. The same values should be
adopted for the PN if the proposed cluster membership will be confirmed.Comment: Accepted for publication in A&
Mass signature of supernova and neutrinos in the Sudbury Neutrino Observatory
Core-collapse supernovae emit of order neutrinos and antineutrinos
of all flavors over several seconds, with average energies of 10--25 MeV. In
the Sudbury Neutrino Observatory (SNO), which begins operations this year,
neutrinos and antineutrinos of all flavors can be detected by reactions which
break up the deuteron. For a future Galactic supernova at a distance of 10 kpc,
several hundred events will be observed in SNO. The and
neutrinos and antineutrinos are of particular interest, as a test of the
supernova mechanism. In addition, it is possible to measure or limit their
masses by their delay (determined from neutral-current events) relative to the
neutrinos (determined from charged-current events). Numerical
results are presented for such a future supernova as seen in SNO. Under
reasonable assumptions, and in the presence of the expected counting
statistics, a or mass down to about 30 eV can be simply
and robustly determined. If zero delay is measured, then the mass limit is
independent of the distance . At present, this seems to be the best
possibility for direct determination of a or mass within
the cosmologically interesting range. We also show how to separately study the
supernova and neutrino physics, and how changes in the assumed supernova
parameters would affect the mass sensitivity.Comment: 12 pages including 4 figures, submitted to Phys. Rev.
About Attitudes and Perceptions: Finding the Proper Way to Consider Latent Variables in Discrete Choice Models
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