| 1. |
- Bernal, Ximena E., et al.
(författare)
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Empowering Latina scientists
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 363:6429, s. 825-826
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Bedell, Megan, et al.
(författare)
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Kepler-11 is a Solar Twin : Revising the Masses and Radii of Benchmark Planets via Precise Stellar Characterization
- 2017
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 839:2
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Tidskriftsartikel (refereegranskat)abstract
- The six planets of the Kepler-11 system are the archetypal example of a population of surprisingly low-density transiting planets revealed by the Kepler mission. We have determined the fundamental parameters and chemical composition of the Kepler-11 host star to unprecedented precision using an extremely high-quality spectrum from Keck-HIRES (R ≃ 67,000, S/N per pixel at 600 nm). Contrary to previously published results, our spectroscopic constraints indicate that Kepler-11 is a young main-sequence solar twin. The revised stellar parameters and new analysis raise the densities of the Kepler-11 planets by between 20% and 95% per planet, making them more typical of the emerging class of "puffy" close-in exoplanets. We obtain photospheric abundances of 22 elements and find that Kepler-11 has an abundance pattern similar to that of the Sun with a slightly higher overall metallicity. We additionally analyze the Kepler light curves using a photodynamical model and discuss the tension between spectroscopic and transit/TTV-based estimates of stellar density.
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| 3. |
- Fomalont, E. B., et al.
(författare)
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THE 2014 ALMA LONG BASELINE CAMPAIGN: AN OVERVIEW
- 2015
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 808:1
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Tidskriftsartikel (refereegranskat)abstract
- A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA) is to make accurate images with resolutions of tens of milliarcseconds, which at submillimeter (submm) wavelengths requires baselines up to similar to 15 km. To develop and test this capability, a Long Baseline Campaign (LBC) was carried out from 2014 September to late November, culminating in end-to-end observations, calibrations, and imaging of selected Science Verification (SV) targets. This paper presents an overview of the campaign and its main results, including an investigation of the short-term coherence properties and systematic phase errors over the long baselines at the ALMA site, a summary of the SV targets and observations, and recommendations for science observing strategies at long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz are also compared to VLA 43 GHz results, demonstrating an agreement at a level of a few percent. As a result of the extensive program of LBC testing, the highly successful SV imaging at long baselines achieved angular resolutions as fine as 19 mas at similar to 350 GHz. Observing with ALMA on baselines of up to 15 km is now possible, and opens up new parameter space for submm astronomy.
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| 4. |
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| 5. |
- Holguín-Veras, J., et al.
(författare)
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The New York city off-hour delivery program: A business and community-friendly sustainability program
- 2018
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Ingår i: Interfaces. - : Institute for Operations Research and the Management Sciences (INFORMS). - 0092-2102 .- 1526-551X. ; 48:1, s. 70-86
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Tidskriftsartikel (refereegranskat)abstract
- The New York City Off-Hour Delivery (NYC OHD) program is the work of a private-public-academic partnership - A collaborative effort of leading private-sector groups and companies, public-sector agencies led by the New York City Department of Transportation, and research partners led by Rensselaer Polytechnic Institute. The efforts of this partnership have induced more than 400 commercial establishments in NYC to accept OHD without supervision. The economic benefits are considerable: The carriers have reduced operational costs and parking fines by 45 percent; the receivers enjoy more reliable deliveries, enabling them to reduce inventory levels; the truck drivers have less stress, shorter work hours, and easier deliveries and parking; the delivery trucks produce 55-67 percent less emissions than they would during regular-hour deliveries, for a net reduction of 2.5 million tons of CO2 per year; and citizens' quality of life increases as a result of reduced conflicts between delivery trucks, cars, bicycles, and pedestrians, and through the use of low-noise delivery practices and technologies that minimize the impacts of noise. The total economic benefits exceed $20 million per year. The success of the OHD program is due largely to the policy design at its core, made possible with the behavioral microsimulation. This unique optimization-simulation system incorporates the research conducted into an operations research/management science tool that assesses the effectiveness of alternative policy designs. This enabled the successful implementation of the project within the most complex urban environment in the United States.
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| 6. |
- Mattila, S., et al.
(författare)
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A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger
- 2018
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 361:6401, s. 482-485
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Tidskriftsartikel (refereegranskat)abstract
- Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the gravitational field of a supermassive black hole (SMBH). We have observed a transient source in the western nucleus of the merging galaxy pair Arp 299 that radiated >1.5 × 1052erg at infrared and radio wavelengths but was not luminous at optical or x-ray wavelengths. We interpret this as a TDE with much of its emission reradiated at infrared wavelengths by dust. Efficient reprocessing by dense gas and dust may explain the difference between theoretical predictions and observed luminosities of TDEs. The radio observations resolve an expanding and decelerating jet, probing the jet formation and evolution around a SMBH.
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| 7. |
- Ramirez-Olivencia, Naim, et al.
(författare)
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Sub-arcsecond imaging of Arp 299-A at 150 MHz with LOFAR: Evidence for a starburst-driven outflow
- 2018
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 610
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first sub-arcsecond (0.44 × 0.41 arcsec 2 ) angular resolution image at 150 MHz of the A-nucleus in the luminous infrared galaxy Arp 299, from International Low Frequency Array (LOFAR) Telescope observations. The most remarkable finding is that of an intriguing two-sided, filamentary structure emanating from the A-nucleus, which we interpret as an outflow that extends up to at least 14 arcsec from the A-nucleus in the N-S direction (≈5 kpc deprojected size) and accounts for almost 40% of the extended emission of the entire galaxy system. We also discuss HST/NICMOS [FeII] 1.64 μm and H 2 2.12 μm images of Arp 299-A, which show similar features to those unveiled by our 150 MHz LOFAR observations, providing strong morphological support for the outflow scenario. Finally, we discuss unpublished Na I D spectra that confirm the outflow nature of this structure. From energetic arguments, we rule out the low-luminosity active galactic nucleus in Arp 299-A as a driver for the outflow. On the contrary, the powerful, compact starburst in the central regions of Arp 299-A provides plenty of mechanical energy to sustain an outflow, and we conclude that the intense supernova (SN) activity in the nuclear region of Arp 299-A is driving the observed outflow. We estimate that the starburst wind can support a mass-outflow rate in the range (11-63 M ⊙ yr -1 ) at speeds of up to 370-890 km s -1 , and is relatively young, with an estimated kinematic age of 3-7 Myr. Those results open an avenue to the use of low-frequency (150 MHz), sub-arcsecond imaging with LOFAR to detect outflows in the central regions of local luminous infrared galaxies.
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| 8. |
- Ramírez Sepúlveda, Jorge Iván
(författare)
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Molecular and clinical sexual dimorphism in systemic autoimmunity
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Biological differences between the sexes of a species, also known as sexual dimorphism, can be found throughout developmental, physiological and pathological processes. In human disease, sexual dimorphism can explain marked differences in disease susceptibility. Rheumatic diseases, such as systemic lupus erythematosus (SLE) and primary Sjögren’s syndrome (pSS), are chronic systemic autoimmune disorders that predominantly affect more women than men. Although many mechanisms have been put forward in order to explain this sex bias, the molecular underpinnings and their translation into disease phenotype are still not fully understood. Therefore, the aim of this thesis was to explore potential sex differences in genetic aspects that contribute to disease development, as well as to characterize clinical features that might exhibit a sexually dimorphic pattern. In Paper I, we studied the expression of genes associated with pSS at basal state in splenic immune cells from wild type mice. The analysis revealed minor differences between female and male murine cells. Similar findings were obtained when human B cells and monocytes were investigated. Although these results suggested potential intrinsic differences, the extent of the sexual dimorphism observed in gene expression of risk loci could not entirely explain the marked sex skew in disease susceptibility. To instead address differences in gene regulation rather than expression, in Paper II we examined whether single nucleotide polymorphisms (SNPs) associated with SLE and pSS could affect the gene expression in a sex-specific manner. The analysis resulted in identification of sex-specific expression quantitative loci (eQTLs) in human B cells. The study of sex-influenced eQTLs in other cell subtypes and in whole blood highlighted the context-dependent effect of these eQTLs. Since variation in gene regulation of risk loci among the sexes can lead to a heterogeneous disease phenotype, in Paper III, Paper IV and Paper V we aimed to identify relevant sex differences in the clinical presentation of incident pSS, prevalent pSS and prevalent SLE, respectively. Our analyses showed that, despite being less prone to systemic autoimmune disorders, men have a more severe disease phenotype, characterized by more organ manifestations, an enhanced serological profile and more critical long-term complications when compared to their female counterparts. In summary, our present work demonstrates the importance of sexual dimorphism in disease susceptibility and phenotype; also, it sheds light on possible molecular mechanisms that orchestrate the immune regulation of these complex disorders. Our results should raise awareness of relevant clinical sex differences that can aid in providing a tailored treatment to these patients. n summary, our present work demonstrates the importance of sexual dimorphism in disease susceptibility and phenotype; also, it sheds light on possible molecular mechanisms that orchestrate the immune regulation of these complex disorders. Our results should raise awareness of relevant clinical sex differences that can aid in providing a tailored treatment to these patients.
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| 9. |
- Varenius, Eskil, 1986, et al.
(författare)
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Subarcsecond international LOFAR radio images of Arp 220 at 150 MHz: A kpc-scale star forming disk surrounding nuclei with shocked outflows
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 593, s. A86-
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Tidskriftsartikel (refereegranskat)abstract
- Context. Arp 220 is the prototypical ultra luminous infrared galaxy (ULIRG). Despite extensive studies, the structure at MHz-frequencies has remained unknown because of limits in spatial resolution.Aims: This work aims to constrain the flux and shape of radio emission from Arp 220 at MHz frequencies.Methods: We analyse new observations with the International Low Frequency Array (LOFAR) telescope, and archival data from the Multi-Element Radio Linked Interferometer Network (MERLIN) and the Karl G. Jansky Very Large Array (VLA). We model the spatially resolved radio spectrum of Arp 220 from 150 MHz to 33 GHz.Results: We present an image of Arp 220 at 150 MHz with resolution 0.̋65 × 0.̋35, sensitivity 0.15 mJy beam-1, and integrated flux density 394 ± 59 mJy. More than 80% of the detected flux comes from extended (6''≈ 2.2 kpc) steep spectrum (α = -0.7) emission, likely from star formation in the molecular disk surrounding the two nuclei. We find elongated features extending 0.3'' (110 pc) and 0.9'' (330 pc) from the eastern and western nucleus respectively, which we interpret as evidence for outflows. The extent of radio emission requires acceleration of cosmic rays far outside the nuclei. We find that a simple three component model can explain most of the observed radio spectrum of the galaxy. When accounting for absorption at 1.4 GHz, Arp 220 follows the FIR/radio correlation with q = 2.36, and we estimate a star formation rate of 220 M⊙ yr-1. We derive thermal fractions at 1 GHz of less than 1% for the nuclei, which indicates that a major part of the UV-photons are absorbed by dust.Conclusions: International LOFAR observations shows great promise to detect steep spectrum outflows and probe regions of thermal absorption. However, in LIRGs the emission detected at 150 MHz does not necessarily come from the main regions of star formation. This implies that high spatial resolution is crucial for accurate estimates of star formation rates for such galaxies at 150 MHz.
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| 10. |
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