2,152 research outputs found

    Editorial: If the settler never came

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    If the settler never came and the (Australian) continent developed herself, what kinds of conversations would we consider? Perhaps, we would highlight the fact that the Country and Island landscape did not have an estimated number of languages but significantly more than the speculated 250 (or “over 300”, or “hundreds of”) Aboriginal and Torres Strait Islander languages across the island and continental landscape. It would be a given continuance that every year across the Country, and not just 2019 declared by the United Nations General assembly, as the year to celebrate the Indigenous languages. Perhaps the ways we define, discuss and distinguish these numerous, living languages would be very different from our current forensic approaches

    Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

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    The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3% for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table, submitted to European Physical Journal

    Implementation and Validation of a High Accuracy UAV-Photogrammetry Based Rail Track Inspection System

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    The regular inspection of the crane tracks of storage cranes at the Container Terminal Altenwerder (CTA), Hamburg requires high accuracy of measurements to determine its position. The allowed tolerances are in the range of 10 mm in the XY plane on a track length of 300 m. The traditional semi-automatic surveying methods are slow and require the interruption of the activities in the storage blocks. The research project AeroInspekt proposed a fully automatic measurement of the position of the tracks using UAV-based photogrammetry. In this paper, the results of the test campaign, carried out in June 2020, were presented where different cameras (150 mm and 80 mm telelens) and flight speeds (1.1 m/s and 1.9 m/s) at a 35 m flying height were performed. Furthermore, an automated rail delineation in the derived surface model was developed and evaluated with ground reference measurements. The results show that the required accuracy of the rail position with an RMSE of 3 mm in XY plane and 8 mm in altitude can be achieved with comparatively less disruption of regular block activities

    iOD907, the first genome-scale metabolic model for the milk yeast Kluyveromyces lactis

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    We describe here the first genome-scale metabolic model of Kluyveromyces lactis, iOD907. It is partially compartmentalized (4 compartments), composed of 1867 reactions and 1476 metabolites. The iOD907 model performed well when assessing the positive growth of K. lactis to Biolog experiments and to an online catalogue of strains that provides information on carbon sources in which K. lactis is able to grow. Chemostat experiments were used to adjust non-growth-associated energy requirements, and the model proved accurate when predicting the biomass, oxygen and carbon dioxide yields. In silico knockouts predicted in vivo phenotypes accurately when compared to published experiments. The iOD907 genome-scale metabolic model complies with the MIRIAM standards for the annotation of enzymes, transporters, metabolites and reactions. Moreover, it contains direct links to KEGG (for enzymes, metabolites and reactions) and to TCDB for transporters, allowing easy comparisons to other models. Furthermore, this model is provided in the well-established SBML format, which means that it can be used in most metabolic engineering platforms, such as OptFlux or Cobra. The model is able to predict the behavior of K. lactis under different environmental conditions and genetic perturbations. Furthermore, it can also be important in the design of minimal media and will allow insights on the milk yeast's metabolism, as well as identifying metabolic engineering targets for the improvement of the production of products of interest by performing simulations and optimizations.The authors thank strategic Project PEst-OE/EQB/LA0023/2013 and project "BioInd - Biotechnology and Bioengineering for improved Industrial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028" co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN, FEDER. The authors would also like to acknowledge Steve Sheridan for proof reading this manuscript

    CEERS: Diversity of Lyman-Alpha Emitters during the Epoch of Reionization

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    We analyze rest-frame ultraviolet to optical spectra of three z7.47z\simeq7.47 - 7.757.75 galaxies whose Lyα\alpha-emission lines were previously detected with Keck/MOSFIRE observations, using the JWST/NIRSpec observations from the Cosmic Evolution Early Release Science (CEERS) survey. From NIRSpec data, we confirm the systemic redshifts of these Lyα\alpha emitters, and emission-line ratio diagnostics indicate these galaxies were highly ionized and metal poor. We investigate Lyα\alpha line properties, including the line flux, velocity offset, and spatial extension. For the one galaxy where we have both NIRSpec and MOSFIRE measurements, we find a significant offset in their flux measurements (5×\sim5\times greater in MOSFIRE) and a marginal difference in the velocity shifts. The simplest interpretation is that the Lyα\alpha emission is extended and not entirely encompassed by the NIRSpec slit. The cross-dispersion profiles in NIRSpec reveal that Lyα\alpha in one galaxy is significantly more extended than the non-resonant emission lines. We also compute the expected sizes of ionized bubbles that can be generated by the Lyα\alpha sources, discussing viable scenarios for the creation of sizable ionized bubbles (>>1 physical Mpc). The source with the highest-ionization condition is possibly capable of ionizing its own bubble, while the other two do not appear to be capable of ionizing such a large region, requiring additional sources of ionizing photons. Therefore, the fact that we detect Lyα\alpha from these galaxies suggests diverse scenarios on escape of Lyα\alpha during the epoch of reionization. High spectral resolution spectra with JWST/NIRSpec will be extremely useful for constraining the physics of patchy reionization.Comment: Submitted to ApJ (18 pages, 7 figures, 2 tables

    CEERS Key Paper VII: Emission Line Ratios from NIRSpec and NIRCam Wide-Field Slitless Spectroscopy at z>2

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    We use James Webb Space Telescope Near-Infrared Camera Wide Field Slitless Spectroscopy (NIRCam WFSS) and Near-Infrared spectrograph (NIRSpec) in the Cosmic Evolution Early Release survey (CEERS) to measure rest-frame optical emission-line of 155 galaxies at z>2. The blind NIRCam grism observations include a sample of galaxies with bright emission lines that were not observed on the NIRSpec masks. We study the changes of the Ha, [OIII]/Hb, and [NeIII]/[OII] emission lines in terms of redshift by comparing to lower redshift SDSS and CLEAR samples. We find a significant (>3σ\sigma) correlation between [OIII]/Hb with redshift, while [NeIII]/[OII] has a marginal (2σ\sigma) correlation with redshift. We compare [OIII]/Hb and [NeIII]/[OII] to stellar mass and Hb SFR. We find that both emission-line ratios have a correlation with Hb SFR and an anti-correlation with stellar mass across the redshifts 0<z<9. Comparison with MAPPINGS~V models indicates that these trends are consistent with lower metallicity and higher ionization in low-mass and high-SFR galaxies. We additionally compare to IllustriousTNG predictions and find that they effectively describe the highest [OIII]/Hb ratios observed in our sample, without the need to invoke MAPPINGS models with significant shock ionizionation components.Comment: 16 pages, 11 figure

    CEERS Spectroscopic Confirmation of NIRCam-Selected z > 8 Galaxy Candidates with JWST/NIRSpec: Initial Characterization of their Properties

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    We present JWST NIRSpec spectroscopy for 11 galaxy candidates with photometric redshifts of z913z\simeq9-13 and MUV[21,18]M_{\rm\,UV} \in[-21,-18] newly identified in NIRCam images in the Cosmic Evolution Early Release Science (CEERS) Survey. We confirm emission line redshifts for 7 galaxies at z=7.7628.998z=7.762-8.998 using spectra at 15μ\sim1-5\mum either with the NIRSpec prism or its three medium resolution gratings. For z9z\simeq9 photometric candidates, we achieve a high confirmation rate of \simeq90\%, which validates the classical dropout selection from NIRCam photometry. No robust emission lines are identified in three galaxy candidates at z>10z>10, where the strong [OIII] and Hβ\beta lines would be redshifted beyond the wavelength range observed by NIRSpec, and the Lyman-α\alpha continuum break is not detected with the current sensitivity. Compared with HST-selected bright galaxies (MUV22M_{\rm\,UV}\simeq-22) that are similarly spectroscopically confirmed at z8z\gtrsim8, these NIRCam-selected galaxies are characterized by lower star formation rates (SFR4M\simeq4\,M_{\odot}~yr1^{-1}) and lower stellar masses (108M\simeq10^{8}\,M_{\odot}), but with higher [OIII]+Hβ\beta equivalent widths (\simeq1100A˚\r{A}), and elevated production efficiency of ionizing photons (log(ξion/Hzerg1)25.8\log(\xi_{\rm\,ion}/{\rm\,Hz\,erg}^{-1})\simeq25.8) induced by young stellar populations (<10<10~Myrs) accounting for 20%\simeq20\% of the galaxy mass, highlighting the key contribution of faint galaxies to cosmic reionization. Taking advantage of the homogeneous selection and sensitivity, we also investigate metallicity and ISM conditions with empirical calibrations using the [OIII]/Hβ\beta ratio. We find that galaxies at z89z\sim8-9 have higher SFRs and lower metallicities than galaxies at similar stellar masses at z26z\sim2-6, which is generally consistent with the current galaxy formation and evolution models.Comment: 21 pages, 11 figures, 2 tables. Submitted to ApJL Focus Issu

    First Look at z &gt; 1 Bars in the Rest-frame Near-infrared with JWST Early CEERS Imaging

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    Stellar bars are key drivers of secular evolution in galaxies and can be effectively studied using rest-frame near-infrared (NIR) images, which trace the underlying stellar mass and are less impacted by dust and star formation than rest-frame UV or optical images. We leverage the power of JWST CEERS NIRCam images to present the first quantitative identification and characterization of stellar bars at z &gt; 1 based on rest-frame NIR F444W images of high resolution (∼1.3 kpc at z ∼ 1-3). We identify stellar bars in these images using quantitative criteria based on ellipse fits. For this pilot study, we present six examples of robustly identified bars at z &gt; 1 with spectroscopic redshifts, including the two highest-redshift bars at z ∼ 2.136 and 2.312 quantitatively identified and characterized to date. The stellar bars at z ∼ 1.1-2.3 presented in our study have projected semimajor axes of ∼2.9-4.3 kpc and projected ellipticities of ∼0.41-0.53 in the rest-frame NIR. The barred host galaxies have stellar masses ∼1 × 10 10 to 2 × 10 11 M ⊙ and star formation rates of ∼21-295 M ⊙ yr −1, and several have potential nearby companions. Our finding of bars at z ∼ 1.1-2.3 demonstrates the early onset of such instabilities and supports simulations where bars form early in massive dynamically cold disks. It also suggests that if these bars at lookback times of 8-11 Gyr survive out to present epochs, bar-driven secular processes may operate over a long time and have a significant impact on some galaxies by z ∼ 0.</p

    First Look at z > 1 Bars in the Rest-Frame Near-Infrared with JWST Early CEERS Imaging

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    Stellar bars are key drivers of secular evolution in galaxies and can be effectively studied using rest-frame near-infrared (NIR) images, which trace the underlying stellar mass and are less impacted by dust and star formation than rest-frame UV or optical images. We leverage the power of {\it{JWST}} CEERS NIRCam images to present the first quantitative identification and characterization of stellar bars at z>1z>1 based on rest-frame NIR F444W images of high resolution (~1.3 kpc at z ~ 1-3). We identify stellar bars in these images using quantitative criteria based on ellipse fits. For this pilot study, we present six examples of robustly identified bars at z>1z>1 with spectroscopic redshifts, including the two highest redshift bars at ~2.136 and 2.312 quantitatively identified and characterized to date. The stellar bars at zz ~ 1.1-2.3 presented in our study have projected semi-major axes of ~2.9-4.3 kpc and projected ellipticities of ~0.41-0.53 in the rest-frame NIR. The barred host galaxies have stellar masses ~ 1×1010 1 \times 10^{10} to 2×10112 \times 10^{11} MM_{\odot}, star formation rates of ~ 21-295 MM_{\odot} yr1^{-1}, and several have potential nearby companions. Our finding of bars at zz ~1.1-2.3 demonstrates the early onset of such instabilities and supports simulations where bars form early in massive dynamically cold disks. It also suggests that if these bars at lookback times of 8-10 Gyr survive out to present epochs, bar-driven secular processes may operate over a long time and have a significant impact on some galaxies by z ~ 0.Comment: 16 pages, 5 figures. Accepted for Publication in Astrophysical Journal Letter
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