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Sensitivity of the redshifted 21 cm signal from the Dark Ages to parameters of primordial magnetic fields
No full textWe analyse the impact of the decaying magnetic turbulence of primordial magnetic fields (PMFs) and ambipolar diffusion on the ionisation and thermal history of the Dark Ages Universe (30 ≤ z ≤ 300), and its imprint on the spectral profile of the global signal in the redshifted 21 cm hydrogen line. The heating function caused by decaying magnetic turbulence monotonically decreases after cosmological recombination; its amplitude strongly depends on the strength of the PMFs’ B0 and weakly depends on the spectral index of the initial power spectrum of the PMFs’ nB. The heating function caused by ambipolar diffusion, in contrast, noticeably depends on the spectral index in the range −3 ≲ nB ≲ 4 but is subdominant in the Dark Ages epoch for PMF models with B0 ≲ 0.5 nG. We computed the ionisation and thermal history of intergalactic gas from the cosmological recombination up to the end of the Dark Ages epoch for a range of PMF parameters, 0.05 ≲ B0 ≲ 0.5 nG, −2.9 ≲ nB ≲ 4, and show the essentially distinguished thermal evolution from one in the Lambda cold dark matter (ΛCDM) model. We also show that the profile of the redshifted 21 cm hydrogen line is very sensitive to the PMF parameters from this range and can be used for their constraints in conjunction with other observational data
PHANGS-JWST: The largest extragalactic molecular cloud catalog traced by polycyclic aromatic hydrocarbon emission
No full textHigh-resolution JWST images of nearby spiral galaxies reveal polycyclic aromatic hydrocarbon (PAH) structures that potentially trace molecular clouds, even CO-dark regions. For this paper, we identified ISM cloud structures in PHANGS-JWST 7.7 μm PAH emission maps for 66 galaxies, smoothed to a common physical resolution of 30 pc and at native resolution. We extracted 108 466 cloud structures in the 30 pc sample and 146 040 clouds in the native resolution sample. We then calculated their molecular properties following a linear conversion from PAH to CO. Given the tendency for clouds in galaxy centers to overlap in velocity space, we opted to flag these clouds and omit them from the analysis in this work. The remaining clouds correspond to giant molecular clouds, such as those detected in CO(2 − 1) emission by ALMA, or lower surface density clouds that either fall below the ALMA detection limits of existing maps or genuinely have no molecular counterpart. We specifically used the homogenized sample for our analysis. Upon cross-matching the PAH clouds to the ALMA CO clouds at a homogenized resolution of 90 pc in 27 galaxies, we find that 41% of the PAH clouds are associated with a CO counterpart. We also show that the converted molecular cloud properties of the PAH clouds do not differ much when compared in different galactic environments. However, outside the central environment, the highest molecular mass surface density clouds are preferentially found in spiral arms. We further apply a lognormal fit to the mass spectra to an unprecedented extragalactic completeness limit of 2 × 103 M⊙, and find that spiral arms contain the most massive clouds compared to other galactic environments. Our findings support the idea that spiral arm gravitational potentials foster the formation of high surface density clouds, and that lower surface density clouds form in the interarm regions. The cloud Σmol values show a decline of a factor of ∼1.5 − 2 toward the outer 2 − 3 Re. However, the trend largely varies in individual galaxies, with flat, decreasing, and even no trend as a function of Rgal. Factors such as large-scale processes, galaxy types, and morphologies might influence the observed trends. We note that combining homogenized molecular properties of individual galaxies leads to the loss of information about the physical processes that are driving deviations in trends of those properties across different galactic environments. We published two catalogs at the CDS, one at the common resolution of 30 pc and another at the native resolution. We expect them to have broad utility for future studies of PAH clouds, molecular clouds, and star formation
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No full textWe present a study of the galaxy merger and interaction activity within the Hyperion Proto-supercluster at z ∼ 2.5 in an effort to assess the occurrence of galaxy mergers and interactions in contrast to the coeval field and their impact on the buildup of stellar mass in high-density environments at higher redshifts. For this work, we utilized data from the Charting Cluster Construction with VUDS and ORELSE Survey (C3VO) along with extensive spectroscopic and photometric datasets available for the COSMOS field – including the HST-Hyperion Survey. To evaluate potential merger and interaction activity, we measured the fraction of galaxies with close kinematic companions (fckc) both within Hyperion and the coeval field by means of a Monte Carlo (MC) methodology developed in this work that probabilistically employs our entire combined spectroscopic and photometric dataset. We validated our fckc MC methodology on a simulated lightcone built from the GAlaxy Evolution and Assembly (GAEA) semi-analytic model, and we determined correction factors that account for the underlying spectroscopic sampling rate of our dataset. We find that galaxies in Hyperion have close kinematic companions ≳2.5× more than galaxies in the field and measure a corrected fckc = % for Hyperion and a corrected fckc = % for the surrounding field; a ≳3σ difference. The enhancement in fckc likely correlates to an enhancement in the merger and interaction activity within the high-density environment of Hyperion and matches the trend seen in other structures. The rate of merger and interactions within the field implied from our field fckc measurement is well aligned with values measured from other observations in similar redshift ranges. The enhanced fckc measured within Hyperion suggests that merger and interaction activity play an important role in the mass growth of galaxies in denser environments at higher redshifts
Retraction Notice: The Effect of Air Injection Flowrate on Nitrate Synthesis with The Addition of Fe2+ Ions Using Plasma Electrolysis
No full textWe take a zero tolerance to any situation where fraudulent research is published in our journals. As a result, this article has been retracted by the Publisher because it is suspected to be a nonsensical computer-generated publication with a number of tortured phrases and irrelevant references.
Additional measures have been implemented to prevent these issues from reoccurring.
EDP Sciences is extremely grateful to anonymous whistleblowers and the Problematic Paper Screene
Les dispositifs d’ancrage temporaires (DAT) - La révolution continue en matière d’ancrage orthodontique
No full textIntroduction : Les dispositifs d’ancrage temporaire (DAT), notamment les minivis orthodontiques, représentent une avancée majeure dans le domaine de l’orthodontie contemporaine. Offrant un ancrage squelettique indépendant de la dentition, ils permettent d’effectuer des mouvements dentaires complexes avec une grande précision, et ce sans dépendre de la coopération du patient. Matériels et méthodes : cet article passe en revue les types d’ancrage utilisés avant l’apparition des DAT, les différentes catégories de minivis, leurs indications cliniques, la technique de pose, les facteurs influençant leur succès ainsi que les complications éventuelles. Résultats : trois cas cliniques sont présentés pour montrer l’efficacité de l’utilisation de minivis comme ancrage dans différentes situations. Discussion : mise en évidence des limites actuelles et des perspectives d’évolution, notamment grâce à l’intégration des technologies 3D, des gabarits chirurgicaux personnalisés et des matériaux innovants
J-PAS: First identification, physical properties, and ionization efficiency of extreme emission line galaxies
No full textContext. Extreme emission line galaxies (EELGs) are believed to significantly contribute to the star formation activity and mass assembly in galaxies. EELGs likely also play a leading role in the cosmic re-ionization as their interstellar medium may allow a significant fraction of their ionizing photons to escape (> 5%). Finding low-redshift analogues of these high-z galaxies is therefore essential to characterizing the physical conditions in the interstellar medium of these galaxies and understanding the processes that re-ionized the Universe.
Aims. We aimed to develop a robust and efficient method for the photometric identification of EELGs using the J-PAS survey. J-PAS will cover approximately 8500 deg2 of the sky with 54 narrow-band filters in the optical range plus i-SDSS, enabling detailed studies of the physical properties of these galaxies. In this work we focused on an initial subset of the survey: a 30 square degree area with complete observations in all bands.
Methods. We combine equivalent width (EW) measurements from J-PAS narrow-band photometry with artificial intelligence techniques to identify galaxies with emission lines exceeding 300 Å. We validated our selection using spectroscopic data from DESI DR1 and characterized the selected sample through spectral energy distribution fitting with CIGAL
Complex Permittivity Measurements with Quasioptical Fabry-Pérot Resonators
No full textAs millimeter instrumentalists push the precision and mapping speed of their instruments ever-higher to make ever-deeper measurements, the need for a precise understanding of the complex permittivity of the dielectrics used in these instruments at their operating temperature heightens. To address this need, we have developed high quality factor quasioptical Fabry-Pérot open resonators spanning 75 GHz-330 GHz, optimized for rapid use in a quick-turnaround 4K cryostat. These hemispherical resonators enable precise metrology of low-loss bulk and thin dielectrics. We present the design and characterization of, and some complex permittivity measurements from, a W-band open resonator
Strong defensive alliances on graph operators
No full textIf is a simple connected graph with vertex set and edge set , we say that a subset is a \emph{strong defensive alliance} if for every vertex the condition holds. The \emph{strong defensive alliance number} is defined as the minimum cardinality among all the strong defensive alliances. A \emph{unitary operator} of graphs assigns to each graph a graph . A few examples of unitary operators of graphs are: Subdivision , , Middle , Total , and Central \C{G}. In this paper we determine the exact values of and . We also characterize the graphs for which the number of strong defensive alliances is , or in and . We also we give tight bounds for , , , , and \alpha(\C{G})
Hybrid gene selection and classification of cancer microarray data using an improved binary firefly algorithm
No full textCancer microarray datasets are distinguished by their high dimensionality and a relatively small sample sizes, which presents significant challenges for accurate cancer classification. Gene selection therefore becomes essential to eliminate irrelevant genes and improve classification accuracy. This paper presents a hybrid approach combining filter and wrapper techniques for gene selection, integrating an improved binary firefly algorithm and the support vector machine classifier. The objective is to select the most cancer-related genes to decrease computation time and enhance classification model performance. Three filter methods (Information Gain Ratio, ReliefF, and Correlation-based Feature Selection) are used in ensemble with the enhanced binary firefly algorithm. The firefly algorithm’s exploration and exploitation capabilities are improved through opposition-based learning during initialization and movement of the fireflies. Additionally, a mutation step is added to improve the diversification of fireflies. To validate our approach, we conducted an experimental study on eight public benchmark datasets and compared it to several recent gene selection methods used for cancer gene expression data classification. The results reveal that the suggested methodology enhances classifier performance while reducing data volume by finding a limited group of genes with strong predictive power for cancer classification
A multi-viewpoint comparison of the velocity field of propagating coronal disturbances
No full textSmall-scale propagating disturbances (PDs) are ubiquitous in the solar corona. The method called time-normalised optical flow (TNOF) was developed for mapping PDs velocity fields in time series of extreme-ultraviolet (EUV) images. We show PDs velocity fields of a quiet-Sun (QS) region containing a small coronal hole (CH) and filament channel (FC) that were jointly observed by Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter and Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). The QS observations acquired on 28 October 2023 in the 174 Å channel of High Resolution EUV Imager (HRIEUV) of EUI and 171 Å channel of AIA were used. During the time of the observations, the separation angle between Solar Orbiter and SDO was approximately 26°. A novel image-alignment analysis shows that the dominant formation heights are 11.4 Mm for HRIEUV and 4 Mm for AIA. Despite this height difference, the PDs velocity fields obtained from the observations from the two instruments agree well throughout the region. In the QS, the median PDs speed is about 6.7 and 7.4 kms−1 for HRIEUV and AIA, respectively, with maximum speeds of about 40 kms−1. The small equatorial CH region is dominated by a low temperature of ≈0.8 MK and is host to high PDs speeds, with a median speed of 17 kms−1. The velocity field bridges coherently across the CH from neighbouring QS regions from east to west, and the CH must therefore be overlaid by a system of long, low-lying closed magnetic loops. This unexpected configuration is supported by a potential field (PF) magnetic model and might be caused by the longevity of the CH, which allows time for interchange reconnection with neighbouring closed-field regions. The FC is observed to be multi-thermal, with a narrow central high-emission strip at low (0.8 MK) and high (2.5 MK) temperatures and low emission at a warm (1.2 MK) temperature. Despite this distinct temperature profile, the PDs speeds in the FC are similar to those of the QS. The TNOF velocity field shows that PDs tend to flow into the FC from neighbouring regions before they align along the FC in a coherent direction. This means that PDs within filaments are driven by external sources. The vector field is consistent with a highly non-potential barbs-and-spine tubular magnetic field; the PF model fails to replicate this configuration. We conclude that longer magnetic loops are required for higher PDs speeds, as observed for CH here, and that the smaller loop systems of the QS and FC generally lead to lower speeds. These multi-instrument results show that the TNOF method can confidently be used as a diagnostic tool for the kinematics of PDs, and it highlights its potential for probing the coronal magnetic field orientation, particularly in highly non-potential regions, where extrapolation models may fail