955 research outputs found
Spectroscopy using the Hadamard Transform V2
The IRMOS (infrared multiobject spectrometer) is an imaging dispersive spectrometer, with a micromirror array to select desired objects. In standard operation, the mirrors are "opened" in patterns such that the resulting spectra do not overlap on the detector. The IRMOS can also be operated in a Hadamard mode, in which the spectra are allowed to overlap, but are modulated by opening the mirrors in many combinations. This mode enables the entire field of view to be observed with the same sensitivity as in the standard mode if the uncertainty is dominated by the detector read noise. We explain the concept and discuss the benefits with an example observation of the Orion Trapezium using the 2.1 m telescope at Kitt Peak National Observatory
The Neon Nova. III. The Infrared Light Curves of Nova QU Vulpeculae (Nova Vul 1984 #2)
We report 1.25 to 19.5 µm broadband infrared (IR) photometric measurements acquired during an eight
year period on the prototypical ONeMg “neon nova” QU Vulpeculae (Nova Vul 1984 #2). The energy distribution of the ejecta evolved through several phases. An early free-free emission phase was followed by an IR coronal phase characterized by the appearance of strong emission lines from forbidden atomic transitions. The lines of [Ne Vi] at 7.6 /xm, and [Ne il] at 12.8 µm were especially strong during the coronal phase. A small amount of silicate dust condensed in the ejecta after about a year. The evidence provided by our IR observations for high abundances of metals in the ejecta of QU Vul is reviewed. We present the IR light curves of QU Vul, and show that the temporal development of its persistent IR coronal emission phase
was evident in the broadband K (2.3 µm) and L (3.6 µm) photometry. Using data from our previous studies of classical novae, we suggest that K and L photometry can distinguish between the slower ONeMg novae with persistent IR coronal activity and CO novae that produce copious quantities of circumstellar dust. The most striking signature is produced in the L band, which contains emission from [Mg Vlll] at 3.02 µm, [A1 Vi] at 3.66 µm, and [Si ix] at 3.92 µm. We comment on the peculiar tendency of the IR light curves of novae to decay exponentially
Biosignatures of Exposure/Transmission and Immunity.
A blood test that captures cumulative exposure over time and assesses levels of naturally acquired immunity (NAI) would provide a critical tool to monitor the impact of interventions to reduce malaria transmission and broaden our understanding of how NAI develops around the world as a function of age and exposure. This article describes a collaborative effort in multiple International Centers of Excellence in Malaria Research (ICEMRs) to develop such tests using malaria-specific antibody responses as biosignatures of transmission and immunity. The focus is on the use of Plasmodium falciparum and Plasmodium vivax protein microarrays to identify a panel of the most informative antibody responses in diverse malaria-endemic settings representing an unparalleled spectrum of malaria transmission and malaria species mixes before and after interventions to reduce malaria transmission
Follow-Up Near-infrared Spectroscopy of Ultraluminous Infrared Galaxies observed by ISO
We present low resolution near-infrared spectroscopy of an unbiased sample of
24 ultraluminous infrared galaxies (ULIRGs), selected from samples previously
observed spectroscopically in the mid-infrared with the Infrared Space
Observatory (ISO). Qualitatively, the near-infrared spectra resemble those of
starbursts. Only in one ULIRG, IRAS 04114-5117E, do we find spectroscopic
evidence for AGN activity. The spectroscopic classification in the
near-infrared is in very good agreement with the mid-infrared one. For a subset
of our sample for which extinction corrections can be derived from Pa-alpha and
Br-gamma, we find rather high Pa-alpha luminosities, in accordance with the
powering source of these galaxies being star formation.[Fe] emission is strong
in ULIRGs and may be linked to starburst and superwind activity. Additionally,
our sample includes two unusual objects. The first, IRAS F00183-7111, exhibits
extreme [Fe] emission and the second, IRAS F23578-5307, is according to our
knowledge one of the most luminous infrared galaxies in H2 rotation-vibration
emission.Comment: Accepted for publication in A&A (12 pages, 4 figures). See
http://www.mpia-hd.mpg.de/homes/dannerb/ for a version with higher quality
figure
Breakthrough capability for the NASA Astrophysics Explorer Program: Reaching the darkest sky
We describe a mission architecture designed to substantially increase the
science capability of the NASA Science Mission Directorate (SMD) Astrophysics
Explorer Program for all AO proposers working within the near-UV to
far-infrared spectrum. We have demonstrated that augmentation of Falcon 9
Explorer launch services with a 13 kW Solar Electric Propulsion (SEP) stage can
deliver a 700 kg science observatory payload to extra-Zodiacal orbit. This new
capability enables up to ~13X increased photometric sensitivity and ~160X
increased observing speed relative to a Sun-Earth L2, Earth-trailing, or Earth
orbit with no increase in telescope aperture. All enabling SEP stage
technologies for this launch service augmentation have reached sufficient
readiness (TRL-6) for Explorer Program application in conjunction with the
Falcon 9. We demonstrate that enabling Astrophysics Explorers to reach
extra-zodiacal orbit will allow this small payload program to rival the science
performance of much larger long development time systems; thus, providing a
means to realize major science objectives while increasing the SMD Astrophysics
portfolio diversity and resiliency to external budget pressure. The SEP
technology employed in this study has strong applicability to SMD Planetary
Science community-proposed missions. SEP is a stated flight demonstration
priority for NASA's Office of the Chief Technologist (OCT). This new mission
architecture for astrophysics Explorers enables an attractive realization of
joint goals for OCT and SMD with wide applicability across SMD science
disciplines.Comment: Submitted to proceedings of the SPIE Astronomical Telescopes and
Instrumentation conference, Amsterdam, The Netherlands, July 201
Epidemiology of Subpatent Plasmodium Falciparum Infection: Implications for Detection of Hotspots with Imperfect Diagnostics.
At the local level, malaria transmission clusters in hotspots, which may be a group of households that experience higher than average exposure to infectious mosquitoes. Active case detection often relying on rapid diagnostic tests for mass screen and treat campaigns has been proposed as a method to detect and treat individuals in hotspots. Data from a cross-sectional survey conducted in north-western Tanzania were used to examine the spatial distribution of Plasmodium falciparum and the relationship between household exposure and parasite density. Dried blood spots were collected from consenting individuals from four villages during a survey conducted in 2010. These were analysed by PCR for the presence of P. falciparum, with the parasite density of positive samples being estimated by quantitative PCR. Household exposure was estimated using the distance-weighted PCR prevalence of infection. Parasite density simulations were used to estimate the proportion of infections that would be treated using a screen and treat approach with rapid diagnostic tests (RDT) compared to targeted mass drug administration (tMDA) and Mass Drug Administration (MDA). Polymerase chain reaction PCR analysis revealed that of the 3,057 blood samples analysed, 1,078 were positive. Mean distance-weighted PCR prevalence per household was 34.5%. Parasite density was negatively associated with transmission intensity with the odds of an infection being subpatent increasing with household exposure (OR 1.09 per 1% increase in exposure). Parasite density was also related to age, being highest in children five to ten years old and lowest in those > 40 years. Simulations of different tMDA strategies showed that treating all individuals in households where RDT prevalence was above 20% increased the number of infections that would have been treated from 43 to 55%. However, even with this strategy, 45% of infections remained untreated. The negative relationship between household exposure and parasite density suggests that DNA-based detection of parasites is needed to provide adequate sensitivity in hotspots. Targeting MDA only to households with RDT-positive individuals may allow a larger fraction of infections to be treated. These results suggest that community-wide MDA, instead of screen and treat strategies, may be needed to successfully treat the asymptomatic, subpatent parasite reservoir and reduce transmission in similar settings
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