71 research outputs found
Wavelength calibration of the JWST-MIRI medium resolution spectrometer
We present the wavelength and spectral resolution characterisation of the
Integral Field Unit (IFU) Medium Resolution Spectrometer for the Mid-InfraRed
Instrument (MIRI), to fly onboard the James Webb Space Telescope in 2014. We
use data collected using the Verification Model of the instrument and develop
an empirical method to calibrate properties such as wavelength range and
resolving power in a portion of the spectrometer's full spectral range (5-28
microns). We test our results against optical models to verify the system
requirements and combine them with a study of the fringing pattern in the
instrument's detector to provide a more accurate calibration. We show that
MIRI's IFU spectrometer will be able to produce spectra with a resolving power
above R=2800 in the wavelength range 6.46-7.70 microns, and that the unresolved
spectral lines are well fitted by a Gaussian profile.Comment: 12 pages, submitted to SPIE Proceedings vol. 7731, Space Telescopes
and Instrumentation 2010: Optical, Infrared, and Millimeter Wav
Modeling the Infrared Bow Shock at delta Velorum: Implications for Studies of Debris Disks and lambda Bootis Stars
We have discovered a bow shock shaped mid-infrared excess region in front of
delta Velorum using 24 micron observations obtained with the Multiband Imaging
Photometer for Spitzer (MIPS). The excess has been classified as a debris disk
from previous infrared observations. Although the bow shock morphology was only
detected in the 24 micron observations, its excess was also resolved at 70
micron. We show that the stellar heating of an ambient interstellar medium
(ISM) cloud can produce the measured flux. Since delta Velorum was classified
as a debris disk star previously, our discovery may call into question the same
classification of other stars. We model the interaction of the star and ISM,
producing images that show the same geometry and surface brightness as is
observed. The modeled ISM is 15 times overdense relative to the average Local
Bubble value, which is surprising considering the close proximity (24 pc) of
delta Velorum.
The abundance anomalies of lambda Bootis stars have been previously explained
as arising from the same type of interaction of stars with the ISM. Low
resolution optical spectra of delta Velorum show that it does not belong to
this stellar class. The star therefore is an interesting testbed for the ISM
accretion theory of the lambda Bootis phenomenon.Comment: 11 pages, 1 table and 13 figures, emulateapj; Accepted for
publication in The Astrophysical Journa
First isolation of Histoplasma capsulatum from the urban bat Eumops bonariensis
Fil: Canteros, C. E. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Iachini, R. H. Instituto Municipal de Zoonosis Luis Pasteur; Argentina.Fil: Rivas, M. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Vaccaro, O. Museo Argentino de Ciencias Naturales Bernardino Rivadavia; Argentina.Fil: Madariaga, J. Instituto Municipal de Zoonosis Luis Pasteur; Argentina.Fil: Galarza, R. Instituto Municipal de Zoonosis Luis Pasteur; Argentina.Fil: Snaiderman, L. Instituto Municipal de Zoonosis Luis Pasteur; Argentina.Fil: Martínez, M. Instituto Municipal de Zoonosis Luis Pasteur; Argentina.Fil: Paladino, M. Instituto Municipal de Zoonosis Luis Pasteur; Argentina.Fil: Cicuttin, G. Instituto Municipal de Zoonosis Luis Pasteur; Argentina.Fil: Varela, E. Museo Argentino de Ciencias Naturales Bernardino Rivadavia; Argentina.Fil: Alcoba, E. Hospital Municipal de Oncología Marie Curie; Argentina.Fil: Zuiani, F. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Sahaza, J. H. UNAM. Departamento de Microbiología y Parasitología; México.Fil: Taylor, M. L. UNAM. Departamento de Microbiología y Parasitología; México.Fil: Davel, Graciela Odelsia. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Se comunica el primer aislamiento de Histoplasma capsulatum var. capsulatum de un murciélago macho de la especie Eumops bonariensis, capturado en la ciudad de Buenos Aires en 2003. Los aislamientos fueron recuperados de bazo e hígado e identificados fenotípicamente. Se los comparó por PCR, con 17 aislamientos clínicos, 12 de pacientes residentes en la ciudad de Buenos Aires y cinco de otros países de América, usando los iniciadores 1283, (GTG)5, (GACA)4 y M13. Con los cuatro iniciadores, los perfiles de los aislamientos de murciélago resultaron idénticos entre sí y más relacionados a los de pacientes de Buenos Aires que a los de otros países (porcentaje de similitud: 91-100% y 55- 87%, respectivamente). La alta relación genética entre los aislamientos obtenidos del murciélago y de los humanos residentes en Buenos Aires sugiere una fuente común de infección. Este es el primer registro de E. bonariensis infectado con H. capsulatum en el mundo, y el primer aislamiento del hongo en la población de quirópteros de la Argentina. Así como estos mamíferos actúan como reservorio y dispersan el hongo en la naturaleza, la infección en murciélagos urbanos podría asociarse al elevado número de casos de histoplasmosis entre pacientes inmunodeprimidos en la ciudad de Buenos Aires
Increasing the Discovery Space in Astrophysics - A Collation of Six Submitted White Papers
We write in response to the call from the 2020 Decadal Survey to submit white
papers illustrating the most pressing scientific questions in astrophysics for
the coming decade. We propose exploration as the central question for the
Decadal Committee's discussions.The history of astronomy shows that paradigm
changing discoveries are not driven by well formulated scientific questions,
based on the knowledge of the time. They were instead the result of the
increase in discovery space fostered by new telescopes and instruments. An
additional tool for increasing the discovery space is provided by the analysis
and mining of the increasingly larger amount of archival data available to
astronomers. Revolutionary observing facilities, and the state of the art
astronomy archives needed to support these facilities, will open up the
universe to new discovery. Here we focus on exploration for compact objects and
multi messenger science. This white paper includes science examples of the
power of the discovery approach, encompassing all the areas of astrophysics
covered by the 2020 Decadal Survey
Constraints on the Physical Properties of GW190814 through Simulations Based on DECam Follow-up Observations by the Dark Energy Survey
On 2019 August 14, the LIGO and Virgo Collaborations detected gravitational waves from a black hole and a 2.6 solar mass compact object, possibly the first neutron star-black hole merger. In search of an optical counterpart, the Dark Energy Survey (DES) obtained deep imaging of the entire 90% confidence level localization area with Blanco/DECam 0, 1, 2, 3, 6, and 16 nights after the merger. Objects with varying brightness were detected by the DES Pipeline, and we systematically reduced the candidate counterparts through catalog matching, light-curve properties, host-galaxy photometric redshifts, Southern Astrophysical Research spectroscopic follow-up observations, and machine-learning-based photometric classification. All candidates were rejected as counterparts to the merger. To quantify the sensitivity of our search, we applied our selection criteria to full light-curve simulations of supernovae and kilonovae as they would appear in the DECam observations. Because the source class of the merger was uncertain, we utilized an agnostic, three-component kilonova model based on tidally disrupted neutron star (NS) ejecta properties to quantify our detection efficiency of a counterpart if the merger included an NS. We find that, if a kilonova occurred during this merger, configurations where the ejected matter is greater than 0.07 solar masses, has lanthanide abundance less than 10-8.56, and has a velocity between 0.18c and 0.21c are disfavored at the 2\u3c3 level. Furthermore, we estimate that our background reduction methods are capable of associating gravitational wave signals with a detected electromagnetic counterpart at the 4\u3c3 level in 95% of future follow-up observations
Whole genome SNP-associated signatures of local adaptation in honeybees of the Iberian Peninsula
The availability of powerful high-throughput genomic tools, combined with genome scans, has helped identifying genes and genetic changes responsible for environmental adaptation in many organisms, including the honeybee. Here, we resequenced 87 whole genomes of the honeybee native to Iberia and used conceptually different selection methods (Samβada, LFMM, PCAdapt, iHs) together with in sillico protein modelling to search for selection footprints along environmental gradients. We found 670 outlier SNPs, most of which associated with precipitation, longitude and latitude. Over 88.7% SNPs laid outside exons and there was a significant enrichment in regions adjacent to exons and UTRs. Enrichment was also detected in exonic regions. Furthermore, in silico protein modelling suggests that several non-synonymous SNPs are likely direct targets of selection, as they lead to amino acid replacements in functionally important sites of proteins. We identified genomic signatures of local adaptation in 140 genes, many of which are putatively implicated in fitness-related functions such as reproduction, immunity, olfaction, lipid biosynthesis and circadian clock. Our genome scan suggests that local adaptation in the Iberian honeybee involves variations in regions that might alter patterns of gene expression and in protein-coding genes, which are promising candidates to underpin adaptive change in the honeybee.John C. Patton, Phillip San Miguel, Paul Parker, Rick Westerman, University of Purdue, resequenced the 87 whole genomes of IHBs. Jose Rufino provided computational resources at IPB. Analyses were performed using the computational resources at the Uppsala Multidisciplinary Center for Advanced Computational Science (UPPMAX), Uppsala University. DH was supported by a PhD scholarship (SFRH/BD/84195/2012) from the Portuguese Science Foundation (FCT). MAP is a member of and receives support from the COST Action FA1307 (SUPER-B). This work was supported by FCT through the programs COMPETE/QREN/EU (PTDC/BIA-BEC/099640/2008) and the 2013-2014 BiodivERsA/FACCE-JPI (joint call for research proposals, with the national funders FCT, Portugal, CNRS, France, and MEC, Spain) to MAP
HD 54272, a classical λ Bootis star and γ Doradus pulsator
We detect the second known λ Bootis star (HD 54272) which exhibits γ Doradus-type pul- sations. The star was formerly misidentified as a RR Lyrae variable. The λ Bootis stars are a small group (only 2 per cent) of late B to early F-type, Population I stars which show moderate to extreme (up to a factor 100) surface underabundances of most Fe-peak elements and solar abundances of lighter elements (C, N, O, and S). The photometric data from the Wide Angle Search for Planets (WASP) and All Sky Automated Survey (ASAS) projects were analysed. They have an overlapping time base of 1566 d and 2545 d, respectively. Six statistically sig-
nificant peaks were identified (f1 = 1.410 116 d−1, f2 = 1.283 986 d−1, f3 = 1.293 210 d−1, f4 = 1.536 662 d−1, f5 = 1.157 22 d−1 and f6 = 0.226 57 d−1). The spacing between f1 and f2, f1 and f4, f5 and f2 is almost identical. Since the daily aliasing is very strong, the interpretation of
frequency spectra is somewhat ambiguous. From spectroscopic data, we deduce a high rota- tional velocity (250 ± 25 km s−1) and a metal deficiency of about −0.8 to −1.1 dex compared to the Sun. A comparison with the similar star, HR 8799, results in analogous pulsational
characteristics but widely different astrophysical parameters. Since both are λ Bootis-type stars, the main mechanism of this phenomenon, selective accretion, may severely influence γ Doradus-type pulsations
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Cause of Death and Predictors of All-Cause Mortality in Anticoagulated Patients With Nonvalvular Atrial Fibrillation : Data From ROCKET AF
M. Kaste on työryhmän ROCKET AF Steering Comm jäsen.Background-Atrial fibrillation is associated with higher mortality. Identification of causes of death and contemporary risk factors for all-cause mortality may guide interventions. Methods and Results-In the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET AF) study, patients with nonvalvular atrial fibrillation were randomized to rivaroxaban or dose-adjusted warfarin. Cox proportional hazards regression with backward elimination identified factors at randomization that were independently associated with all-cause mortality in the 14 171 participants in the intention-to-treat population. The median age was 73 years, and the mean CHADS(2) score was 3.5. Over 1.9 years of median follow-up, 1214 (8.6%) patients died. Kaplan-Meier mortality rates were 4.2% at 1 year and 8.9% at 2 years. The majority of classified deaths (1081) were cardiovascular (72%), whereas only 6% were nonhemorrhagic stroke or systemic embolism. No significant difference in all-cause mortality was observed between the rivaroxaban and warfarin arms (P=0.15). Heart failure (hazard ratio 1.51, 95% CI 1.33-1.70, P= 75 years (hazard ratio 1.69, 95% CI 1.51-1.90, P Conclusions-In a large population of patients anticoagulated for nonvalvular atrial fibrillation, approximate to 7 in 10 deaths were cardiovascular, whereasPeer reviewe
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