101,608 research outputs found
Time series observations with the mid-infrared instrument (MIRI) on JWST
No full textTime-variable phenomena such as transiting exoplanets will be a major science theme for the James Webb Space Telescope (JWST). For Guaranteed Time and Early Release Science Observations, over 500 hours of JWST time have been allocated to time series observations (TSOs) of transiting exoplanets. Several dedicated observing modes are available in the instrument suite, whose operations are specifically tailored to these challenging observations. MIRI, the only JWST instrument covering the wavelength range longwards of 5 mu m on JWST, will offer TSOs in two of its modes: the low resolution spectrometer, and the imager. In this paper we will describe these modes for MIRI, and discuss how they differ operationally from regular (non-TSO) observations. We will show performance estimates based on ground testing and modeling, discuss the most relevant detector effects for high precision (spectro-)photometry, and provide some guidelines for planning MIRI TSOs.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
Letter, [Author unclear] to Paulina T. Merritt
No full textHandwritten letter to Paulina Merritt from an unknown author, October 1, 1876.
EPOCHS Paper - VIII. An insight into MIRI-selected galaxies in SMACS-0723 and the benefits of deep MIRI photometry in revealing AGN and the dusty universe
Full text linkWe present the analysis of the stellar population and star formation history of 181 MIRI selected galaxies at z = 0 - 3.5 in the massive galaxy cluster field SMACS J0723.3-7327, commonly referred to as SMACS0723, using the JWST Mid-Infrared Instrument (MIRI). We combine the data with the JWST Near Infrared Camera (NIRCam) catalogue, in conjunction with the Hubble Space Telescope (HST) WFC3/IR and ACS imaging. We find that the MIRI bands capture PAH features and dust emission, significantly enhancing the accuracy of photometric redshift and measurements of the physical properties of these galaxies. The median photo-z's of galaxies with MIRI data are found to have a small 0.1 per cent difference from spectroscopic redshifts and reducing the error by 20 per cent. With MIRI data included in SED fits, we find that the measured stellar masses are unchanged, while the star formation rate is slightly lower by 0.1 dex. We also fit the median SED of active galactic nuclei (AGNs) and star-forming galaxies (SFG) separately. MIRI data provides tighter constraints on the AGN contribution, reducing the typical AGN contributions by ∼15 per cent. In addition, we also compare the median SED obtained with and without MIRI, and we find that including MIRI data yields steeper optical and UV slopes, indicating bluer colours, lower dust attenuation, and younger stellar populations. In the future, MIRI/MRS will enhance our understanding by providing more detailed spectral information and allowing for the study of specific emission features and diagnostics associated with AGN
High-precision cryogenic wheel mechanisms of the JWST/MIRI instrument: performance of the flight models
No full textThe Mid Infrared Instrument (MIRI) aboard JWST is equipped with one filter wheel and two dichroic-grating wheel mechanisms to reconfigure the instrument between observing modes such as broad/narrow-band imaging, coronagraphy and low/medium resolution spectroscopy. Key requirements for the three mechanisms with up to 18 optical elements on the wheel include: (1) reliable operation at T = 7 K, (2) high positional accuracy of 4 arcsec, (3) low power dissipation, (4) high vibration capability, (5) functionality at 7 K < T < 300 K and (6) long lifetime (5-10 years). To meet these requirements a space-proven wheel concept consisting of a central MoS2-lubricated integrated ball bearing, a central torque motor for actuation, a ratchet system with monolithic CuBe flexural pivots for precise and powerless positioning and a magnetoresistive position sensor has been implemented. We report here the final performance and lessons-learnt from the successful acceptance test program of the MIRI wheel mechanism flight models. The mechanisms have been meanwhile integrated into the flight model of the MIRI instrument, ready for launch in 2014 by an Ariane 5 rocket
Peningkatan Kinerja Guru di SMKN 1 Miri Kabupaten Sragen
Full text linkTujuan dari penelitian ini adalah untuk memastikan pengaruh variabel-variabel berikut; supervisi, integritas, budaya organisasi, dan etos kerja pada kinerja guru di SMK N 1 Miri kabupaten Sragen baik secara bersamaan maupun sebagian. Peneliti menggunakan metode deskriptif kuantitatif. Populasi penelitian ini adalah guru SMK N 1 Miri kabupaten Sragen yang terdiri dari 90 guru. Teknik pengambilan sampel menggunakan teknik sampling jenuh/sensus yang meliputi 90 guru. Peneliti menggunakan kuesioner untuk mengumpulkan data. Sedangkan metode analisis data menggunakan analisis statistik linier berganda uji regresi, uji F, uji T, dan koefisien determinasi. Hasil penelitian menunjukkan bahwa supervisi, integritas, budaya organisasi, dan etos kerja semuanya memiliki pengaruh sebesar 47,9 %. terhadap kinerja guru. Sebagai perbandingan, 52,1% dipengaruhi oleh variabel lain seperti kemampuan kerja, disiplin kerja, pendidikan dan lain-lai
Handwritten biographical information on Paulina T. McClung Merritt
No full textA handwritten biography of Paulina T. McClung Merritt by an unknown author, 1892.
Heterogeneous and tissue-specific regulation of effector T cell responses by IFN-gamma during Plasmodium berghei ANKA infection.
Full text linkIFN-γ and T cells are both required for the development of experimental cerebral malaria during Plasmodium berghei ANKA infection. Surprisingly, however, the role of IFN-γ in shaping the effector CD4(+) and CD8(+) T cell response during this infection has not been examined in detail. To address this, we have compared the effector T cell responses in wild-type and IFN-γ(-/-) mice during P. berghei ANKA infection. The expansion of splenic CD4(+) and CD8(+) T cells during P. berghei ANKA infection was unaffected by the absence of IFN-γ, but the contraction phase of the T cell response was significantly attenuated. Splenic T cell activation and effector function were essentially normal in IFN-γ(-/-) mice; however, the migration to, and accumulation of, effector CD4(+) and CD8(+) T cells in the lung, liver, and brain was altered in IFN-γ(-/-) mice. Interestingly, activation and accumulation of T cells in various nonlymphoid organs was differently affected by lack of IFN-γ, suggesting that IFN-γ influences T cell effector function to varying levels in different anatomical locations. Importantly, control of splenic T cell numbers during P. berghei ANKA infection depended on active IFN-γ-dependent environmental signals--leading to T cell apoptosis--rather than upon intrinsic alterations in T cell programming. To our knowledge, this is the first study to fully investigate the role of IFN-γ in modulating T cell function during P. berghei ANKA infection and reveals that IFN-γ is required for efficient contraction of the pool of activated T cells
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Petroleum geology-related sites in and around Miri, Sarawak, Malaysia: potential geotourism resources
No full textThis paper discusses the petroleum geology-related sites in and around Miri, in the state of Sarawak, Malaysia and their potentials as geotourism resources. Desk study was conducted by reviewing some literatures related to the topic and the study area. A field visit was conducted in May 2014 to observe the recent situation of all sites in details. There are some geological/natural and man-made features in and around the city which are closely related to petroleum geology. The Canada hill (anticline), a unique tectonic feature which emerged from the surrounding coastal plain, is a petroleum trap and used to be the location of many oil wells. On top of this hill is the location of the first oil well (called "the Grand Old Lady") and Miri Petroleum Museum. The deltaic sandstone outcrops of Miri Formation (such as the Airport Road outcrop and other outcrops around Miri) are very ideal outcrops of sandstone reservoirs. Oil seeps, mud volcanoes, and oil sands are some evidences of petroleum occurrences in and around the city. Niah Caves can be seen as an analogue of carbonate reservoirs. All these sites and features can attract people to visit the city, not only geologists and geology students who want to study the petroleum geology of Miri area, but also the common people who are interested in such a field
Investigating aerosols as a way to reconcile K2-18 b JWST MIRI and NIRISS/NIRSpec observations
No full textInternational audienceRecent JWST observations of the temperate sub-Neptune K2-18 b with NIRISS SOSS/NIRSpec G395H and MIRI LRS have yielded apparently inconsistent results: the MIRI spectra exhibit spectral features nearly twice as large as those seen at shorter wavelengths, challenging the high-metallicity, CH4-rich nonequilibrium model that fits the NIRISS/NIRSpec data. We performed a suite of atmospheric retrievals on both datasets, including free-chemistry, nonequilibrium, and aerosol models, using laboratory-derived complex refractive indices for a variety of photochemical haze analogs. Free retrievals systematically output lower metallicities than inferred by self-consistent chemical disequilibrium models, and the inclusion of absorbing aerosols, especially CH4-dominated, nitrogen-poor tholins, can further reduce the inferred metallicity by over an order of magnitude. These hazes reproduce the observed NIRISS slope through scattering and match MIRI features via C–H bending absorption near 7 μm, while yielding particle properties consistent with photochemical production in H2-rich atmospheres. Although their inclusion improves the joint fit and reduces tension between datasets, it also significantly lowers the retrieved CH4 abundance, highlighting degeneracies between metallicity, composition, and aerosol properties. Our results underscore the importance of aerosol absorption in interpreting temperate sub-Neptune spectra and motivate future JWST observations and laboratory work to break these degeneracies
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