bluuebunny/crossref_metadata_2025 huggingface dataset:
Local sequence‐structure relationships in proteins
Authors: Škrbić Tatjana , Maritan Amos , Giacometti Achille , Banavar Jayanth R.
Published: January 2021

We seek to understand the interplay between amino acid sequence and local structure in proteins. Are some amino acids unique in their ability to fit harmoniously into certain local structures? What is the role of sequence in sculpting the putative native state folds from myriad possible conformations? In order to address these questions, we represent the local structure of each Cα atom of a protein by just two angles, θ and μ, and we analyze a set of more than 4,000 protein structures from the PDB. We use a hierarchical clustering scheme to divide the 20 amino acids into six distinct groups based on their similarity to each other in fitting local structural space. We present the results of a detailed analysis of patterns of amino acid specificity in adopting local structural conformations and show that the sequence‐structure correlation is not very strong compared with a random assignment of sequence to structure. Yet, our analysis may be useful to determine an effective scoring rubric for quantifying the match of an amino acid to its putative local structure.
Protective effect of glycyrrhizin on coronary microembolization‐induced myocardial dysfunction in rats
Authors: Yuan Yonggang , Li Bing , Peng Wanzhong , Xu Zesheng
Published: January 2021

Coronary microembolization (CME)‐induced inflammation and cardiomyocyte apoptosis are two key factors contributing to CME‐induced myocardial dysfunction. High‐mobility group box‐1 (HMGB1) plays essential role in progression of CME‐induced injury and inhibition of HMGB1 has been shown to be protective. In present study, the potential effects of glycyrrhizin, a HMGB1 inhibitor, on CME‐induced myocardial dysfunction are evaluated. Using a rat model of CME, we administrated glycyrrhizin in rats prior to CME induction. The level of HMGB1, TNF‐α, iNOS, IL‐6, IL‐1β, cleaved caspase‐3, Bax, and Bcl‐2 were measured. The serum level of cardiac troponin I, creatine kinase, was detected. The cardiac function and cardiomyocyte apoptosis were evaluated. The activation of TLR4/NF‐κB signaling pathway was analyzed. Glycyrrhizin prevented CME‐induced production of HMGB1, TNF‐α, iNOS, IL‐6, and IL‐1β. Glycyrrhizin inhibited CME‐induced cardiomyocyte apoptosis and the expression of cleaved caspase‐3 and Bax, while enhanced the expression of Bcl‐2. Glycyrrhizin decreased cardiac troponin I and creatine kinase levels and improved cardiac function. Glycyrrhizin prevented the activation of HMGB1/TLR4/NF‐κB signaling pathway. Glycyrrhizin ameliorated myocardial dysfunction in CME rats by preventing inflammation and apoptosis of cardiomyocytes.
Reactor rate modulation oscillation analysis with two detectors in Double Chooz
Authors:   The Double Chooz collaboration, Abrahão T. , Almazan H. , dos Anjos J. C. , Appel S. , Barriere J. C. , Bekman I. , Bezerra T. J. C. , Bezrukov L. , Blucher E. , Brugière T. , Buck C. , Busenitz J. , Cabrera A. , Cerrada M. , Chauveau E. , Chimenti P. , Corpace O. , Dawson J. V. , Djurcic Z. , Etenko A. , Furuta H. , Gil-Botella I. , Givaudan A. , Gomez H. , Gonzalez L. F. G. , Goodman M. C. , Hara T. , Haser J. , Hellwig D. , Hourlier A. , Ishitsuka M. , Jochum J. , Jollet C. , Kale K. , Kaneda M. , Karakac M. , Kawasaki T. , Kemp E. , de Kerret H. , Kryn D. , Kuze M. , Lachenmaier T. , Lane C. E. , Lasserre T. , Lastoria C. , Lhuillier D. , Lima H. P. , Lindner M. , López-Castaño J. M. , LoSecco J. M. , Lubsandorzhiev B. , Maeda J. , Mariani C. , Maricic J. , Martino J. , Matsubara T. , Mention G. , Meregaglia A. , Miletic T. , Milincic R. , Minotti A. , Navas-Nicolás D. , Novella P. , Oberauer L. , Obolensky M. , Onillon A. , Oralbaev A. , Palomares C. , Pepe I. M. , Pronost G. , Reichenbacher J. , Reinhold B. , Schönert S. , Schoppmann S. , Scola L. , Sharankova R. , Sibille V. , Sinev V. , Skorokhvatov M. , Soldin P. , Stahl A. , Stancu I. , Stokes L. F. F. , Suekane F. , Sukhotin S. , Sumiyoshi T. , Sun Y. , Veyssiere C. , Viaud B. , Vivier M. , Wagner S. , Wiebusch C. , Yang G. , Yermia F.
Published: January 2021

Abstract

A θ13 oscillation analysis based on the observed antineutrino rates at the Double Chooz far and near detectors for different reactor power conditions is presented. This approach provides a so far unique simultaneous determination of θ13 and the total background rates without relying on any assumptions on the specific background contributions. The analysis comprises 865 days of data collected in both detectors with at least one reactor in operation. The oscillation results are enhanced by the use of 24.06 days (12.74 days) of reactor-off data in the far (near) detector. The analysis considers the $$ {\overline{\nu}}_e $$

ν
¯

e

interactions up to a visible energy of 8.5 MeV, using the events at higher energies to build a cosmogenic background model considering fast-neutrons interactions and 9Li decays. The background-model-independent determination of the mixing angle yields sin2(2θ13) = 0.094 ± 0.017, being the best-fit total background rates fully consistent with the cosmogenic background model. A second oscillation analysis is also performed constraining the total background rates to the cosmogenic background estimates. While the central value is not significantly modified due to the consistency between the reactor-off data and the background estimates, the addition of the background model reduces the uncertainty on θ13 to 0.015. Along with the oscillation results, the normalization of the anti-neutrino rate is measured with a precision of 0.86%, reducing the 1.43% uncertainty associated to the expectation.
Does methotrexate cause progressive fibrotic interstitial lung disease? A systematic review
Authors: Dawson Julie K. , Quah Edmond , Earnshaw Ben , Amoasii Constanta , Mudawi Tareg , Spencer Lisa G.
Published: January 2021

The aim is to evaluate the published evidence on whether methotrexate (MTX) use causes progressive fibrotic interstitial lung disease (fILD). This PRISMA-compliant systematic review has been registered electronically with PROSPERO 2018 ID CRD42018087838, Centre of review and dissemination at the University of York. A total of 29 articles met the inclusion criteria. Thirteen articles were found to support the claim that MTX causes fILD. They all had a low Downs and Black quality score (< 6/27). Their ‘risk of bias’ assessment scores indicated serious to critical risk of bias. The 16 articles rejecting the claim that MTX causes fILD were of higher quality as indicated by their Downs and Black score. Their ‘risk of bias’ assessment scores suggested only a low to moderate risk of bias. This systematic literature review supports the finding that MTX does not cause fILD in humans. Three studies suggest that MTX treatment may actually improve outcomes in patients with rheumatoid arthritis (RA) associated fILD by slowing down ILD progression.
No secret hiding place? Absence of SARS-CoV-2 on the ocular surface of 1145 hospitalized patients in a pandemic area
Authors: Rokohl Alexander C. , Grajewski Rafael S. , Wawer Matos Philomena A. , Koch Hannah-Leah , Dewald Felix , Klein Florian , Fätkenheuer Gerd , Lehmann Clara , Cursiefen Claus , Heindl Ludwig M.
Published: January 2021

Objectives

The aims of this study were to evaluate the isolated prevalence of real-time reverse transcriptase-polymerase chain reaction (RT-PCR)–confirmed SARS-CoV-2 on the ocular surface without systemic infection in hospitalized asymptomatic patients and to determine the risk for ophthalmologists and medical staff to be infected by prescreened asymptomatic patients in a tertiary eye care center.

Methods

In this prospective, observational study, bilateral swaps of the conjunctiva in the lower fornices as well as nasopharyngeal swaps were collected in 1145 hospitalized asymptomatic patients of a tertiary eye care center. Real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was performed for each swap to evaluate the prevalence of SARS-CoV-2. Demographic data and potential risk factors for an isolated infection of the ocular surface were noted.

Results

Two thousand two hundred eighty-eight (99.9%) of all 2290 tested eyes had negative results in the RT-PCR analysis of the conjunctival swabs. One patient had bilateral false-positive results in the conjunctival swabs. None of the 1145 patients had any positive RT-PCR-confirmed result in the nasopharyngeal swabs.

Conclusions

The risk for an isolated conjunctival viral activity in patients with a negative nasopharyngeal swab-based RT-PCR seems to be absent or extremely low, suggesting no need to perform additional conjunctival swabs in patients with negative nasopharyngeal swabs. Furthermore, the risk of a work-related SARS-CoV-2 infection due to direct contact with preselected asymptomatic patients in an eye care center is very low, especially when additional hygiene standards and safe distances are respected carefully. This might reassure medical staff and reduce the fear of SARS-CoV-2 infection.
Antibody response in patients admitted to the hospital with suspected SARS-CoV-2 infection: results from a multicenter study across Spain
Authors: Fuentes Ana , Serrano-Conde Esther , Roldán Carolina , Benito-Ruesca Rafael , Mejías Gregoria , Sampedro Antonio , March-Roselló Gabriel , Fernández-Natal Isabel , Esperalba Juliana , Rodríguez Mario José , Martínez de Aguirre Paula , Salas Carlos , Roc María Lourdes , Soria Luis Miguel , Parra-Grande Mónica , Montero María Dolores , Fernández-Roblas Ricardo , Franco-Álvarez de Luna Francisco , Lozano Carmen , García Federico
Published: January 2021

Aim

To evaluate the serological response against SARS-CoV-2 in a multicenter study representative of the Spanish COVID pandemic.

Methods

IgG and IgM + IgA responses were measured on 1466 samples from 1236 Spanish COVID-19 patients admitted to the hospital, two commercial ELISA kits (Vircell SL, Spain) based on the detection of antibodies against the viral spike protein and nucleoprotein, were used.

Results

Approximately half of the patients presented antibodies (56.8% were IgM + IgA positive and 43.0% were IgG positive) as soon as 2 days after the first positive PCR result. Serological test positivity increased with time from the PCR test, and 10 days after the first PCR result, 91.5% and 88.0% of the patients presented IgM + IgA and IgG antibodies, respectively.

Conclusion

The high values of sensitivity attained in the present study from a relatively early period of time after hospitalization support the use of the evaluated serological assays as supplementary diagnostic tests for the clinical management of COVID-19.
MALINTZIN AS A CONQUISTADORA AND WARRIOR WOMAN IN THE LIENZO DE TLAXCALA (c. 1552)
Authors: ROGERS CLAUDIA J.
Published: January 2021

This article foregrounds a new interpretation of the Lienzo de Tlaxcala, an indigenous-authored source depicting the Tlaxcalteca's role in the conquest of Mexico, from 1519 to 1521. It analyses this document's unique visual portrayal of Malintzin, an indigenous woman who acted as Hernando Cortés's translator during the conquest, amid the battle for the Aztec capital of Tenochtitlan. Challenging the traditional perception of Malintzin as a peaceful mediator, the Lienzo demonstrates that its Tlaxcalan authors saw her as a powerful warrior or conquistadora, who was intricately connected with violent acts of conquest. By contextualizing depictions of Malintzin as a warrior within the wider entanglement of female figures with violence and warfare, this article underscores indigenous perceptions of the conquest and contributes to the wider, critical deconstruction of triumphalist, Eurocentric narratives. With a particular focus on indigenous associations of Malintzin with the Virgin Mary, this article explores the significance ascribed to these two figures by the Lienzo's authors and their city.
Survival and function following pharyngo-laryngo-oesophagectomy in Wales: a twelve-year case series
Authors: Edwards D R , Pope L , Berry S
Published: January 2021

Objective

Treatment of locally advanced hypopharyngeal cancer can cause significant morbidity and late toxicity. Pharyngo-laryngo-oesophagectomy can achieve adequate surgical margins, but data on survival and functional outcome are limited, especially in Wales. This study aimed to describe mortality, morbidity and functional outcome following pharyngo-laryngo-oesophagectomy in a Welsh population.

Method

This study was a retrospective case note review of pharyngo-laryngo-oesophagectomy cases in Wales over 12 years.

Results

Fifteen patients underwent pharyngo-laryngo-oesophagectomy; all but one underwent gastric pull-up. Median survival and disease-free survival were 17 months (range, 2–53 months) and 14 months. Censored 3-month, 1-year and 3-year survival was 93, 71 and 50 per cent, respectively. Common Terminology Criteria for Adverse Events grading of long-term dysphagia was 1 in 58 per cent, 2 in 33 per cent and 3 in 8 per cent, and 87.5 per cent achieved a ‘moderate’ or ‘good’ voice rehabilitation.

Conclusion

These results demonstrate favourable survival and reasonable functional outcome following pharyngo-laryngo-oesophagectomy, suggesting pharyngo-laryngo-oesophagectomy should be considered in all appropriate surgical candidates.
The Problem of Expressive Action
Authors: Bennett Christopher
Published: January 2021

Rational explanation of action out of emotion faces a number of challenges. The Wrong Explanation Challenge says that explaining action out of emotion by reference to a purpose rather than an emotion gets it wrong. The Redundancy Challenge says that if explanation of an action by reference to emotion is sufficient then rational explanation is redundant. And the No Further Justification Challenge says that there is no more to say, at the level of rational explanation, about why people act as they do out of a particular emotion. Furthermore, even if these challenges can be addressed, there is a Problem of Expressive Action, since many actions out of emotion seem unpromising candidates for being guided by normative practical reasons of the prudential, instrumental, deontic or consequentialist sort. In response, I argue that many actions out of emotions should be understood as expressive actions guided by the agent's conception of normative practical reasons: specifically, their conception of expressive reasons.
Comparative characterisation of human and ovine non-aureus staphylococci isolated in Sardinia (Italy) for antimicrobial susceptibility profiles and resistance genes
Authors: Longheu C. M. , Azara E. , Attene S. , Sanna S. , Sale M. , Addis M. F. , Tola S.
Published: January 2021

We present the comparative characterisation of 195 non-aureus staphylococci (NAS) isolates obtained from sheep (n = 125) and humans (n = 70) in Sardinia, Italy, identified at the species level by gap gene polymerase chain reaction (PCR) followed by restriction fragment length polymorphism analysis with AluI. Isolates were tested phenotypically with a disc diffusion method and genotypically by PCR, for resistance to 11 antimicrobial agents including cationic antiseptic agents. Among the ovine isolates, Staphylococcus epidermidis (n = 57), S. chromogenes (n = 29), S. haemolyticus (n = 17), S. simulans (n = 8) and S. caprae (n = 6) were the most prevalent species, while among human isolates, S. haemolyticus (n = 28) and S. epidermidis (n = 26) were predominant, followed by S. lugdunensis and S. hominis (n = 4). Of the 125 ovine isolates, 79 (63.2%) did not carry any of the resistance genes tested, while the remainder carried resistance genes for at least one antibiotic. The highest resistance rates among ovine isolates were recorded against tetracycline (20.8%), and penicillin (15.2%); none was resistant to methicillin and two exhibited multidrug resistance (MDR); one of which was positive for the antiseptic resistance smr gene. By contrast, most human isolates (59/70, 84.3%) were resistant to ⩾1 antimicrobials, and 41 (58.6%) were MDR. All 52 (74.3%) penicillin-resistant isolates possessed the blaZ gene, and 33 of 70 (47.1%) harboured the mec gene; of these, seven were characterised by the Staphylococcal Chromosomal Cassette (SCCmec) type IV, 6 the type V, 5 of type III and one representative each of type I and type II. The majority (57.1%) was erythromycin-resistant and 17 isolates carried only the efflux msrA gene, 11 the methylase ermC gene and an equal number harboured both of the latter genes. Moreover, 23 (32.8%) were tetracycline-resistant and all but one possessed only the efflux tetK gene. qacA/B and smr genes were detected in 27 (38.6%) and 18 (25.7%) human NAS, respectively. These results underline a marked difference in species distribution and antimicrobial resistance between ovine and human-derived NAS.
Multiwavelength surveys for Active Galactic Nuclei
Authors: Brandt William Nielsen
Published: January 2021

Most of what we know about active galactic nuclei (AGNs) has been driven, or at least strongly shaped, by our methods for finding them, and multiwavelength AGN surveys have achieved remarkable successes in recent decades. I will present a broad, and thus necessarily shallow, review of such multiwavelength AGN surveys. I will first present some brief introductory points on, e.g., general survey approaches, AGN luminosities, host galaxies, and anisotropic emission/obscuration. I will then review many of the key current surveys and their results, separating these into ground-based and space-based surveys. Finally, I will discuss some future prospects including essential remaining questions and “discovery space” considerations.
Unveiling the physical processes that regulate galaxy evolution with SPICA observations
Authors: Spinoglio Luigi , Fernández-Ontiveros Juan A. , Mordini Sabrina
Published: January 2021

To study the dust obscured phase of the galaxy evolution during the peak of the Star Formation Rate (SFR) and the Black Hole Accretion Rate (BHAR) density functions (z = 1–4), rest frame mid-to-far infrared (IR) spectroscopy is needed. At these frequencies, dust extinction is at its minimum and a variety of atomic and molecular transitions, tracing most astrophysical domains, occur. The future IR space telescope mission, SPICA, fully redesigned with its 2.5m mirror cooled down to T < 8K, will be able to perform such observations. With SPICA, we will: 1) obtain a direct spectroscopic measurement of the SFR and of the BHAR histories, 2) measure the evolution of metals and dust to establish the matter cycle in galaxies, 3) uncover the feedback and feeding mechanisms in large samples of distant galaxies, either AGN- or starburst-dominated, reaching lookback times of nearly 12 Gyr. SPICA large-area deep surveys will provide low-resolution, mid-IR spectra and continuum fluxes for unbiased samples of tens of thousands of galaxies, and even the potential to uncover the youngest, most luminous galaxies in the first few hundred million years. In this paper a brief review of the scientific preparatory work that has been done in extragalactic astronomy by the SPICA Consortium will be given.
A uniformly selected, all-sky, optical AGN catalogue
Authors: Zaw Ingyin
Published: January 2021

We have constructed an all-sky AGN catalogue, based on optical spectroscopy, from the parent sample of galaxies in the 2MASS Redshift Survey (2MRS), a near-complete census of the nearby (z < 0.09) universe. In addition to identifying the 8491 AGNs and providing line measurements for all the emission line galaxies so that the users can customise the selection criteria, we assess the affects of spectral quality on AGN identification. We find that spectral signal-to-noise and resolution affect not only the overall AGN detection rates but also the broad-line to narrow-line AGN ratios. These systematic effects must be taken into account when using any optical AGN catalogue and in comparing the results from different catalogues. We develop a way to account for the inhomogeneities by parametrizing the AGN detection rates as a function of the spectral signal-to-noise, making our catalogue suitable for statistical analyses. We will also present cross-correlation studies between this catalogue and all-sky catalogs at other wavelengths to better understand the different physical processes which lead to the emission at different wavelengths.
Spectroscopic properties of radio-loud and radio-quiet quasars
Authors: Chakraborty Avinanda , Bhattacharjee Anirban
Published: January 2021

Surveys have shown radio-loud (RL) quasars constitute 10%-15% of the total quasar population and rest are radio-quiet (RQ). However, it is unknown if this radio-loud fraction (RLF) remains consistent among different parameter spaces. This study shows that RLF increases for increasing full width half maximum (FWHM) velocity of the Hβ broad emission line (z < 0.75). To analyse the reason, we compared bolometric luminosity of RL and RQ quasars sample which have FWHM of Hβ broad emission line greater than 15000km/s (High Broad Line or HBL) with which have FWHM of Hβ emission line less than 2500km/s (Low Broad Line or LBL). From the distributions we can conclude for the HBL, RQ and RL quasars are peaking separately and RL quasars are having higher values whereas for the LBL the peaks are almost indistinguishable. We predicted selection effects could be the possible reason but to conclude anything more analysis is needed. Then we compared our result with Wills & Brotherton (1995) and have shown that some objects from our sample do not follow the pattern of the logR vs FWHM plot where R is the ratio of 5 GHz radio core flux density with the extended radio lobe flux density.
The properties of the dusty inner regions of nearby QSOs
Authors: Aretxaga Itziar
Published: January 2021

We present MIR spectroscopy and photometry obtained with CanariCam on the 10.4 m Gran Telescopio CANARIAS for a sample of 20 nearby, MIR bright and X-ray luminous quasi-stellar objects (QSOs). We find that for the majority of QSOs the MIR emission is unresolved at angular scales ∼0.3 arcsec. We derive the properties of the dusti tori that surround the nucleus based on these observations and find significant differences in the parameters compared with a sample of Seyfert 1 and 2 nuclei. We also find evidence for polycyclic aromatic hydrocarbon (PAH) features in the spectra, indicative of star formation, more centrally peaked (on scales of a few hundred pc) than previously believed.
A status report on AGN variability
Authors: Lira Paulina
Published: January 2021

Active Galactic Nuclei (AGN) are ubiquitous variable sources. This trademark property allows the study of many aspects of AGN physics which are not possible by other means. In this review I summarize what has been learnt by the close monitoring of AGN flux variations with special emphasis in studies conducted in optical and near-infrared domain. I also highlight what knowledge is still missing from our picture of AGN phenomena, as well as possible developments expected in this new era of time-domain astronomy.
The study of variability of 8 blazar candidates among the Fermi-LAT unidentified gamma-ray sources
Authors: Nkundabakura Pheneas , Kamanzi Jean D’amour , Mbarubucyeye Jean D. , Mutabazi Tom
Published: January 2021

We discuss the time-series behavior of 8 extragalactic 3FGL sources away from the Galactic plane (i.e., |b|⩾10°) whose uncertainty ellipse contains a single X-ray and one radio source. The analysis was done using the standard Fermi ScienceTools, package of version v10r0p5. The results show that sources in the study sample display a slight indication of flux variability in γ-ray on monthly timescale. Furthermore, based on the object location on the variability index versus spectral index diagram, the positions of 4 objects in the sample were found to fall in the region of the already known BL Lac positions.
Role of environment on AGN activity
Authors: Amiri Amirnezam
Published: January 2021

Motivated by the apparently conflicting results reported in the literature on the effect of environment on nuclear activity, we have carried out a new analysis by comparing the fraction of galaxies hosting active galactic nuclei (AGNs) in the most overdense regions (rich galaxy clusters) and the most underdense ones (voids) in the local universe. Exploiting the classical BPT diagnostics, we have extracted volume limited samples of star forming and AGN galaxies. We find that, at variance with star-forming galaxies, AGN galaxies have similar distributions of specific star formation rates and of galactic ages (as indicated by the Dn4000 parameter) both in clusters and in voids. In both environments galaxies hosting AGNs are generally old, with low star formation activity. The AGN fraction increases faster with stellar mass in clusters than in voids, especially above 1010.2 M⊙. Our results indicate that, in the local universe, the nuclear activity correlates with stellar mass and galaxy morphology and is weakly, if at all, affected by the local galaxy density.
Dirt-cheap gas scaling relations: Using dust attenuation and galaxy radius to predict gas masses for large samples of AGNs
Authors: Yesuf Hassen
Published: January 2021

We analyze the molecular and atomic gas data from the GALEX Arecibo SDSS Survey (xGASS) and the extended CO Legacy Database (xCOLD GASS) IRAM survey using novel survival analysis techniques to identify a small number of stellar properties that best correlate with the gas mass. We find that the dust absorption, AV, and the stellar half-light radius, R50, are likely the two best secondary parameters than improve the Kennicutt - Schmidt type relation between the gas mass and the star formation rate, SFR. We fit multiple regression, taking into account gas mass upper limits, to summarize the median, mean, and the 0.15/0.85 quantile multivariate relationships between the gas mass (atomic or molecular hydrogen), SFR, AV and/or R50. In particular, we find that the AV of both the stellar continuum and nebular gas emission shows a significant partial correlation with the molecular hydrogen after controlling for the effect of SFR. The partial correlation between the AV and the atomic gas, however, is weak and their zero-order correlation may be explained by SFR. This is expected since in poorly dust-shielded regions molecular hydrogen is dissociated by the far ultraviolet photons and HI is the dominant phase. Similarly, R50 shows significant partial correlations with both atomic and molecular gas masses. This hints at the importance of environment (e.g., galacto-centric distance) on the gas contents galaxies and on the interplay between gas and star formation rate. We apply the gas scaling relations we found to a large sample of type 2 and type 1 AGNs and infer that the gas mass correlates with AGN luminosity. This correlation is inconsistent with the prediction of AGN feedback models that strong AGNs remove or heat cold gas in their host galaxies.
AGN fueling and feedback
Authors: Combes Francoise
Published: January 2021

Dynamical mechanisms are essential to exchange angular momentum in galaxies, drive the gas to the center, and fuel the central super-massive black holes. While at 100pc scale, the gas is sometimes stalled in nuclear rings, recent observations reaching ∼10pc scale have revealed, within the sphere of influence of the black hole, smoking gun evidence of fueling. Observations of AGN feedback are described, together with the suspected responsible mechanisms. Molecular outflows are frequently detected in active galaxies with ALMA and NOEMA, with loading factors between 1 and 5. When driven by AGN with escape velocity, these outflows are therefore a clear way to moderate or suppress star formation. Molecular disks, or tori, are detected at 10pc-scale, kinematically decoupled from their host disk, with random orientation. They can be used to measure the black hole mass.
Radiative feedback of low-Lbol/LEdd AGNs
Authors: Xie Fu-Guo
Published: January 2021

AGN feedback, through either radiation or kinematics by expelled medium, plays a crucial role in the coevolution of supermassive black hole (SMBH) and its host galaxy. The nuclei spend most of their time as low-luminosity AGNs (LLAGNs), whose spectra are distinctive to bright AGNs, and the feedback is the hot mode (also named kinetic mode). We thus investigate the radiative heating in the hot mode. We calculate the value of “Compton temperature” Tc, which defines the heating capability of the radiation at given flux, and find that Tc∼(5−15)×107 K, depending on the spectrum of individual LLAGNs. This work provides a cheap way to include the radiative heating of LLAGNs in the study of AGN feedback.
Do AGN really suppress star formation?
Authors: Harrison Chris M. , Alexander David M. , Rosario Dalton J. , Scholtz Jan , Stanley Flora
Published: January 2021

Active galactic nuclei (AGN) are believed to regulate star formation inside their host galaxies through “AGN feedback”. We summarise our on-going study of luminous AGN (z ∼ 0.2−3; LAGN,bol 1043 erg s−1), which is designed to search for observational signatures of feedback by combining observed star-formation rate (SFR) measurements from statistical samples with cosmological model predictions. Using the EAGLE hydrodynamical cosmological simulations, in combination with our Herschel + ALMA surveys, we show that – even in the presence of AGN feedback – we do not necessarily expect to see any relationships between average galaxy-wide SFRs and instantaneous AGN luminosities. We caution that the correlation with stellar mass for both SFR and AGN luminosity can contribute to apparent observed positive trends between these two quantities. On the other hand, the EAGLE simulations, which reproduce our observations, predict that a signature of AGN feedback can be seen in the wide specific SFR distributions of all massive galaxies (not just AGN hosts). Overall, whilst we can not rule out that AGN have an immediate small-scale impact on in-situ star-formation, all of our results are consistent with a feedback model where galaxy-wide in-situ star formation is not rapidly suppressed by AGN, but where the feedback likely acts over a longer timescale than a single AGN episode.
Ionized AGN outflows are less powerful than assumed: A multi-wavelength census of outflows in type II AGN
Authors: Baron Dalya
Published: January 2021

In this talk I will show that multi-wavelength observations can provide novel constraints on the properties of ionized gas outflows in AGN. I will present evidence that the infrared emission in active galaxies includes a contribution from dust which is mixed with the outflow and is heated by the AGN. We detect this infrared component in thousands of AGN for the first time, and use it to constrain the outflow location. By combining this with optical emission lines, we constrain the mass outflow rates and energetics in a sample of 234 type II AGN, the largest such sample to date. The key ingredient of our new outflow measurements is a novel method to estimate the electron density using the ionization parameter and location of the flow. The inferred electron densities, ∼104.5 cm−3, are two orders of magnitude larger than found in most other cases of ionized outflows. We argue that the discrepancy is due to the fact that the commonly-used [SII]-based method underestimates the true density by a large factor. As a result, the inferred mass outflow rates and kinetic coupling efficiencies are 1–2 orders of magnitude lower than previous estimates, and 3–4 orders of magnitude lower than the typical requirement in hydrodynamic cosmological simulations. These results have significant implications for the relative importance of ionized outflows feedback in this population.
Feedback from quasars: The prevalence and impact of radio jets
Authors: Jarvis Miranda
Published: January 2021

I will present our ongoing multi-wavelength study on the prevalence and impact of radio jets in a sample of z < 0.2 type 2 ‘obscured’ quasars who’s high bolometric luminosities make them ideal local analogues of distant, more common, quasars. Despite being classified as ‘radio quiet’ (log L[1.4GHz] = 23.3 - 24.4 W/Hz), our high spatial resolution (∼0.25”) radio observations (VLA and eMERLIN) reveal jet like structures on 1–25kpc scales in ∼80% of the sample. Our integral field spectroscopy reveals jet-ISM interaction and outflows in all cases. Our work suggests that radio jets are an important feedback mechanism even during a typical ‘quasar’ phase. Using ALMA and APEX we are now investigating the impact of these jets and outflows on the molecular, star forming, gas; looking for signs of depletion and excitation. Preliminary results suggest a depleted molecular gas supply in these sources. I will present all of these results, focused on our pilot study of 10 targets and then introduce our on-going work on an expanded sample of 42 low-redshift quasars. Our latest results come from MUSE/AO and ALMA from which we are carefully characterising the properties of the ionised and molecular outflows at sub-kpc resolution.
Observing AGN sources with the Event Horizon Telescope
Authors: Wielgus Maciek
Published: January 2021

In April 2017 Event Horizon Telescope (EHT) has delivered first resolved images of a shadow of a supermassive black hole. Apart from black hole sources in M87 and in the Galactic Center, observed with resolution comparable to the Schwarzschild radius scale, EHT observed multiple AGN sources during the 2017 campaign. These include 3C279, Centaurus A, OJ287 and more. For most of the considered sources EHT 2017 data set should allow to reconstruct images with highest angular resolution in the history of their observations, approaching 20 uas. While the analysis of these data is still ongoing, I will talk about the scientific opportunities related to observing AGN sources with the extreme resolution of the EHT as well as about the astrophysical questions that these observations may help answering.
AGN astrometry: A powerful tool for galaxy kinematic studies
Authors: Kimani Naftali , Brunthaler Andreas , Menten Karl M.
Published: January 2021

This article highlights the successes of the high resolution astrometric VLBI observations used for measuring proper motion of galaxies in the Local group. The required, high accuracies, often in the μ as yr−1 regime, are only attainable through the use of the phase-referencing technique. These require either a compact radio source (AGN) or strong maser emission in the target galaxy and, additionally, some compact extra-galactic radio sources (quasars) to serve as ideal background reference source. The derived proper motions can lead to lower limits on the orbital lower estimates to the mass of the host galaxy, promise a new handle on dynamical models of interacting galaxy systems and offer insights on the spatial distribution of dark matter in the near universe.
Luminosity functions and quasar lifetimes in a sample of mid-IR selected quasars
Authors: Ridgway Susan E.
Published: January 2021

We have made a spectroscopic survey of luminous AGNs and quasars selected in the mid-infrared from Spitzer IRAC surveys. Mid-infrared selection is less affected by dust obscuration, and we find more high redshift quasars than are found in optical or hard X-ray surveys. We have derived luminosity functions for obscured and unobscured quasar populations, and we use these and spectral energy distribution fits to place constraints on host galaxy properties and quasar lifetimes.
Dichotomy of radio loud and radio quiet quasars in four dimensional eigenvector one (4DE1) parameter space
Authors: Terefe Shimeles , del Olmo Ascensión , Marziani Paola , Pović Mirjana
Published: January 2021

Recent work has shown that it is possible to systematize quasars (QSOs) spectral diversity in 4DE1 parameter space. The spectra contained in most of the surveys have low signal to noise ratio which fed the impression that all QSOâ€™s are spectroscopically similar. Exploration of 4DE1 parameter space gave rise to the concept of two populations of QSOs that present important spectroscopic differences. We aim to quantify broad emission line differences between radio quiet and radio loud sources by exploiting more complete samples of QSO with spectral coverage in Hβ, MgII and CIV emission lines. We used a high redshift sample (0.35 < z < 1) of strong radio emitter QSOs observations from Calar Alto Observatory in Spain.
Determination of K4000 of potential blazar candidates among EGRET unidentified gamma-ray sources
Authors: Uwitonze Emmanuel , Nkundabakura Pheneas , Mutabazi Tom
Published: January 2021

Blazars are radio-loud Active Galactic Nuclei (AGN) with relativistic jets oriented towards the observer’s line-of-sight. Based on their optical spectra, blazars may be classified as flat-spectrum radio quasars (FSRQs) or BL Lacs. FSRQs are more luminous blazars with both narrow and broad emission and absorption lines, while BL Lacs are less luminous and featureless. Recent studies show that blazars dominate (˜93%) the already-identified EGRET sources (142), suggesting that among the unidentified sources (129) there could still be faint blazars. Due to the presence of a strong non-thermal component inside their jets, blazars are found to display a weaker depression at ˜4000 Å (K 4000 ≤ 0.4). In this study, we aimed at determining the K 4000 break for a selected sample among the potential blazar candidates from unidentified EGRET sources to confirm their blazar nature. We used two blazar candidates, 3EG J1800-0146 and 3EG J1709-0817 associated with radio counterparts, J1802-0207 and J1713-0817, respectively. Their optical counterparts were obtained through spectroscopic observations using Robert Stobie spectrograph (RSS) at the Southern African Large Telescope (SALT) in South Africa. The observed Ca II H & K lines depression at ˜4000 Å in spectra of these sources show a shallow depression, K 4000 = 0.35 ± 0.02 and 0.24 ± 0.01, respectively, suggesting that these sources are blazar candidates. Moreover, the redshifts z = 0.165 and 0.26 measured in their spectra confirm the extragalactic nature of these sources.
Peering into the heart of darkness: Radio VLBI survey of the NEP deep field
Authors: Gelfand Joseph
Published: January 2021

Active Galactic Nuclei (AGN), accreting supermassive black holes at the centers of galaxies, are believed to produce powerful outflows – often observed as radio jets – which significantly influence the evolution of the surrounding galaxy and inter-galactic medium. However, how these jets – which are produced in the central parsecs of the AGN – impact gas on scales thousands to millions times larger is poorly understood. Doing so requires measuring the properties on all the relevant size scales. In this talk I will present initial results from the deepest-ever radio VLBI survey of an extragalactic field, whose milli-arcsecond angular resolution allows us to probe the central parsecs around these AGN. By comparing the radio properties of the detected radio jets with the multi-wavelength properties of their host galaxies, we are better to understand what galaxies generate powerful radio jets, and how do these outflows affect their host galaxies.
Stellar populations and ages of ultra-hard X-ray AGN in the BASS survey
Authors: Pović Mirjana
Published: January 2021

Connection between star formation and AGN activity has been studied widely over the past years, which shown to be very important for understanding better the role of AGN in galaxy evolution. In this context, what are the stellar ages and average stellar populations of AGN host galaxies, and if there are any differences depending on AGN type, are still open questions that brought many inconsistencies, very often due to different selection criteria used. The AGN sample detected in the ultra-hard X-rays (14–195 keV) by the Swift BAT telescope is not affected by obscuration nor is it contaminated by stellar emission, and presents some of the most unbiased samples. In this talk we will present the results obtained on AGN stellar populations and ages through spectral fittings by using the Swift-BAT AGN Spectroscopic Survey (BASS) which gives us an unique opportunity to understand better the connection between AGN and their host galaxies.
Adaptive optics imaging and spectroscopy of the radio galaxy 3C294
Authors: Quirrenbach Andreas
Published: January 2021

3C 294 is a powerful FR II type radio galaxy at z = 1.786. Due to its proximity of a bright star, it has been subject to several adaptive optics supported imaging studies. The system shows a clumpy structure indicative of a merging system. There is even tentative evidence that 3C 294 hosts a dual AGN. In order to distinguish between the various scenarios for 3C 294 we performed deep high-resolution adaptive optics imaging and optical spectroscopy of 3C 294 with the Large Binocular Telescope. We resolve the 3C 294 system in three distinct components separated by a few tenths of an arcsecond. One of them is compact, the other two are extended. The nature of the latter is unclear. They could be a single galaxy with an internal dust absorption feature, a galaxy merger, or two galaxies at different redshifts. We can now uniquely associate the radio source of 3c 294 with one of the extended components. Based on our spectroscopy, we determine a slightly different redshift of z = 1.784. We find, however, in addition a single emission line at a wavelength of 6745 AA, which might be identified with Lyα at z = 4.56. It thus appears unlikely that 3C294 hosts a dual AGN; it might rather be a pair of AGNs with very small projected separation.
The circum-nuclear environment and jets of active galaxies at z ∼ 0: Recent results from a multi-frequency investigation
Authors: Shastri Prajval
Published: January 2021

We report results from a multi-frequency investigation of very nearby accreting supermassive black holes. We seek to test the hypothesis that imprints of AGN feedback are present at z ˜ 0. Our sample contains about 130 AGN which were chosen to have redshifts less than 0.02, so our optical imaging typically has several spatial resolution elements across the host galaxy. In addition to optical IFU measurements for all the 130 objects, we have GMRT and archival VLA imaging for subsets of the sample, and also ATCA, ASTROSAT and Chandra observations for select objects. We present our most recent results based on the multi-frequency data, for the systematics of the sample as a whole and on individual objects, that includes a binary black hole precursor.
An accreting < 105M⊙ black hole at the center of dwarf galaxy IC750
Authors: Zaw Ingyin
Published: January 2021

Nuclear black holes in dwarf galaxies are important for understanding the low end of the supermassive black hole mass distribution and the black hole-host galaxy scaling relations. IC 750 is a rare system which hosts an AGN, found in ˜0.5% of dwarf galaxies, with circumnuclear 22 GHz water maser emission, found in ˜3–5% of Type 2 AGNs. Water masers, the only known tracer of warm, dense gas in the center parsec of AGNs resolvable in position and velocity, provide the most precise and accurate mass measurements of SMBHs outside the local group. We have mapped the maser emission in IC 750 and find that it traces a nearly edge-on warped disk, 0.2 pc in diameter. The central black hole has an upper limit mass of ˜1 × 105 M⊙ and a best fit mass of ˜8 × 104 M⊙, one to two orders of magnitude below what is expected from black hole-galaxy scaling relations. This has implications for models of black hole seed formation in the early universe, the growth of black holes, and their co-evolution with their host galaxies.
Testing stellar evolution models
Authors: Negu Seblu H. , Tessema Solomon Belay
Published: January 2021

In this study, we have investigated the stellar evolution models using the open-source software instrument Modules for Experiments in Stellar Astrophysics. We examine the evolution of angular momentum and the stability of mass transfer in the evolution of Algol-type binaries through the inner Lagrangian point via the Roche lobe overflow. Also, we have determined the ongoing challenge of chemical mixing and exhibit improvements that make easier the simulation of Algol-type binaries evolution.
Accelerating universe in modified teleparallel gravity theory
Authors: Sahlu Shambel , Ntahompagaze Joseph , Abebe Amare , Mota David F.
Published: January 2021

This paper studies the cosmology of accelerating expansion of the universe in modified teleparallel gravity theory. We discuss the cosmology of f(T, B) gravity theory and its implication to the new general form of the equation of state parameter wTB for explaining the late-time accelerating expansion of the universe without the need for the cosmological constant scenario. We examine the numerical value of wTB in different paradigmatic f(T, B) gravity models. In those models, the numerical result of wTB is favored with observations in the presence of the torsion scalar T associated with a boundary term B and shows the accelerating expansion of the universe.
The study of short orbital period of delta scuti pulsating variable stars
Authors: Mohammed Abduselam
Published: January 2021

As a pulsating star moves in its binary orbit, the path length of the light between us and the star varies, leading to the periodic variation in the arrival time of the signal from the star to us (earth). With the consideration of pulsators light arrival time delay effects several new methods which allows using Kepler photometric data (light curves) alone to find binary stars have been recently developed. Among these modern techniques we used binarogram method and we identified that several δSct pulsating stars have companions. The application of these method on detecting long periods(i.e. longer than about 50 d) δSct pulsating stars is not new, but the uniqueness of this study is we verified that it is also applicable to detect and determine the orbital elements of short periods (i.e short orbital period) δSct pulsating stars. With this investigation, we identified the possible way to overcome effects of fictious peaks, even, on the maximum peaks helpful to verify weather the star has companion or not depend up on the existence of the time-delay. Then, we applied the technique on known binary stars and their orbital elements are previously published. Finally, we identified some new short orbital period δSct pulsating stars and obtained their orbital frequency and period with the same procedures. Because of with our attempts we succeeded and verified the applicability of the method (the Binarogram method) on these stars (i.e short orbital period) for the first time, we expect that our present study will play a great role for similar study and to improve our binary statistics.