The archaeology of a landslide: Unravelling the Azores earthquake disaster of 1522 and its consequences

The multidisciplinary research described here shows how archaeologists can help reconstruct past seismic episodes and understand the subsequent relief operation, rehabilitation, and reconstruction processes. In October 1522, a major earthquake and landslide struck the then capital of the Azores, Vila Franca do Campo, 1500 km from the European mainland. Damage was extensive, destroying key monuments, affecting most of the inhabited area, and leaving few survivors among the early colonists. The results from twenty-six archaeological trenches, geological and geoarchaeological investigations, and documentary analysis are reviewed here. Distinctive archaeological deposits are identified and explained, using the high density of artefacts and the erosional contact between the landslide and the pre-1522 palaeosol to reconstruct the episode in detail

A novel Bayesian approach for decomposing the radio emission of quasars: I. Modelling the radio excess in red quasars

© 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/Studies show that both radio jets from the active galactic nuclei (AGNs) and the star formation (SF) activity in quasar host galaxies contribute to the quasar radio emission; yet their relative contributions across the population remain unclear. Here, we present an improved parametric model that allows us to statistically separate the SF and AGN components in observed quasar radio flux density distributions, and investigate how their relative contributions evolve with AGN bolometric luminosity (\L\mathrm\bol\\) and redshift (z) using a fully Bayesian method. Based on the newest data from LOw-Frequency ARray Two-metre Sky Survey data release 2, our model gives robust fitting results out to \z\\, showing a quasar host galaxy SF rate (SFR) evolution that increases with bolometric luminosity and with redshift out to \z\\. This differs from the global cosmic SFR density, perhaps due to the importance of galaxy mergers. The prevalence of radio AGN emissions increases with quasar luminosity, but has little dependence on redshift. Furthermore, our new methodology and large sample size allow us to subdivide our data set to investigate the role of other parameters. Specifically, in this paper, we explore quasar colour and demonstrate that the radio excess in red quasars is due to an enhancement in AGN-related emission, since the host galaxy SF contribution to the total radio emission is independent of quasar colour. We also find evidence that this radio enhancement occurs mostly in quasars with weak or intermediate radio power.Peer reviewe

An acoustic emission landslide early warning system for communities in low-income and middle-income countries

This is an Open Access Article. It is published by Springer under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/Early warning systems for slope instability are needed to alert users of accelerating slope deformation behaviour, enable evacuation of vulnerable people, and conduct timely repair and maintenance of critical infrastructure. Communities exposed to landslide risk in low- and middle-income countries seldom currently instrument and monitor slopes to provide a warning of instability because existing techniques are complex and prohibitively expensive. Research and field trials have demonstrated conclusively that acoustic emission (AE) monitoring can be an effective approach to detect accelerating slope movements and to subsequently communicate warnings to users. The objective of this study was to develop and assess a simple, robust, low-cost AE monitoring system to warn of incipient landslides, which can be widely deployed and operated by communities globally to help protect vulnerable people. This paper describes a novel AE measurement sensor that has been designed and developed with the cost constrained to a few hundred dollars (US). Results are presented from physical model experiments that demonstrate performance of the AE system in measuring accelerating deformation behaviour, with quantifiable relationships between AE and displacement rates. Exceedance of a pre-determined trigger level of AE can be used to communicate an alarm to users in order to alert them of a slope failure. Use of this EWS approach by communities worldwide would reduce the number of fatalities caused by landslides

How does the radio enhancement of broad absorption line quasars relate to colour and accretion rate?

The origin of radio emission in different populations of radio-quiet quasars is relatively unknown, but recent work has uncovered various drivers of increased radio-detection fraction. In this work, we pull together three known factors: optical colour (g - i), C IV distance (a proxy for L/LEdd), and whether or not the quasar contains broad absorption lines (BALQSOs) which signify an outflow. We use SDSS (Sloan Digital Sky Survey) DR14 spectra along with the LOFAR Two Metre Sky Survey Data Release 2 and find that each of these properties have an independent effect. BALQSOs are marginally more likely to be radio-detected than non-BALQSOs at similar colours and L/LEdd, moderate reddening significantly increases the radio-detection fraction and the radio detection increases with L/LEdd above a threshold for all populations. We test a widely used simple model for radio wind shock emission and calculate energetic efficiencies that would be required to reproduce the observed radio properties. We discuss interpretations of these results concerning radio-quiet quasars more generally. We suggest that radio emission in BALQSOs is connected to a different physical origin than the general quasar population since they show different radio properties independent of colour and C IV distance

Exploring the radio-loudness of SDSS quasars with spectral stacking

© 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/We use new 144 MHz observations over 5634 deg 2 from the LOFAR (Low Frequency Array) Two-metre Sky Survey (LoTSS) to compile the largest sample of uniformly selected, spectroscopically confirmed quasars from the 14th data release of the Sloan Digital Sky Survey (SDSS-DR14). Using the classical definition of radio loudness, R = log (L 1.4GHz/L i), we identify 3697 radio-loud (RL) and 111 132 radio-quiet (RQ) sources at 0.6 < z < 3.4. To study their properties, we develop a new rest-frame spectral stacking algorithm, designed with forthcoming massively multiplexed spectroscopic surveys in mind, and use it to create high signal-to-noise composite spectra of each class, matched in redshift and absolute i-band magnitude. We show that RL quasars have redder continuum and enhanced [O II] emission than their RQ counterparts. These results persist when additionally matching in black hole mass, suggesting that this parameter is not the defining factor in making a quasi-stellar object (QSO) RL. We find that these features are not gradually varying as a function of radio loudness, but are maintained even when probing deeper into the RQ population, indicating that a clear-cut division in radio loudness is not apparent. Upon examining the star formation rates (SFRs) inferred from the [O II] emission line, with the contribution from active galactic nucleus removed using the [Ne V] line, we find that RL quasars have a significant excess of star formation relative to RQ quasars out to z = 1.9 at least. Given our findings, we suggest that RL sources either preferably reside in gas-rich systems with rapidly spinning black holes, or represent an earlier obscured phase of QSO evolution.Peer reviewe

Volume Characteristics of Landslides Triggered by the MW 7.8 2016 Kaikōura Earthquake, New Zealand, Derived From Digital Surface Difference Modeling

We use a mapped landslide inventory coupled with a 2‐m resolution vertical difference model covering an area of 6,875 km2 to accurately constrain landslide volume‐area relationships. We use the difference model to calculate the source volumes for landslides triggered by the MW 7.8 Kaikōura, New Zealand, earthquake of 14 November 2016. Of the 29,519 mapped landslides in the inventory, 28,394 are within the analysis area, and of these, we have calculated the volume of 17,256 source areas that are ≥90% free of debris. Of the 28,394 landslides, about 80% are classified as soil or rock avalanches and the remainder as mainly translational slides. Our results show that both the soil avalanches and the rock avalanches, ignoring their source geology, have area to volume power‐law scaling exponents (γ) of 0.921 to 1.060 and 1.040 to 1.138, respectively. These are lower than the γ values of 1.1–1.3 (for soil) and 1.3–1.6 (for rock) reported in the literature for undifferentiated landslide types. They are, however, similar to those γ values estimated from other coseismic landslide inventories. In contrast, for 50 selected rotational, translational (planar slide surfaces), or compound slides, where much of the debris remains in the source area, we found γ values range between 1.46 and 1.47, indicating that their slide surfaces were considerably deeper than those landslides classified as avalanches. This study, like previous studies on coseismic landslides, shows that soil and rock avalanches (disrupted landslides) are the dominant landslide type triggered by earthquakes and that they tend to be shallow.Key PointsWe use a 2‐m resolution vertical difference model to estimate source volumes for 17,256 landslides with sources ≥90% free of debris triggered by the MW7.8 2016 Kaikōura EarthquakeThe model was derived by subtracting a tectonically adjusted pre‐EQ surface model from a post‐EQ model, covering an area of 6,875 km2Landslide trigger mechanism, type/failure mode, and source material are critical for accurate estimation of landslide volumes from source‐area geometriesPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/156166/2/jgrf21176.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/156166/1/jgrf21176_am.pd

A panchromatic view of infrared quasars: excess star formation and radio emission in the most heavily obscured systems

To understand the active galactic nuclei (AGNs) phenomenon and their impact on the evolution of galaxies, a complete AGN census is required; however, finding heavily obscured AGNs is observationally challenging. Here we use the deep and extensive multiwavelength data in the COSMOS field to select a complete sample of 578 infrared (IR) quasars (LAGN,IR > 1045 erg s−1) at z < 3, with minimal obscuration bias, using detailed UV-to-far-IR spectral energy distribution (SED) fitting. We complement our SED constraints with X-ray and radio observations to further investigate the properties of the sample. Overall, 322 of the IR quasars are detected by Chandra and have individual X-ray spectral constraints. From a combination of X-ray stacking and L2−10 kev – L6 μm analyses, we show that the majority of the X-ray faint and undetected quasars are heavily obscured (many are likely Compton thick), highlighting the effectiveness of the mid-IR band to find obscured AGNs. We find that 355 (≈61 per cent) IR quasars are obscured (NH > 1022 cm−2) and identify differences in the average properties between the obscured and unobscured quasars: (1) obscured quasars have star formation rates ≈3 times higher than unobscured systems for no significant difference in stellar mass and (2) obscured quasars have stronger radio emission than unobscured systems, with a radio-loudness parameter ≈ 0.2 dex higher. These results are inconsistent with a simple orientation model but in general agreement with either extreme host-galaxy obscuration towards the obscured quasars or a scenario where obscured quasars are an early phase in the evolution of quasars

Induction of insulin-like growth factor 2 expression in a mesenchymal cell line co-cultured with an ameloblast cell line

Various growth factors have been implicated in the regulation of cell proliferation and differentiation during tooth development. It has been unclear if insulin-like growth factors (IGFs) participate in the epithelium–mesenchyme interactions of tooth development. We previously produced three-dimensional sandwich co-culture systems (SW) containing a collagen membrane that induce the differentiation of epithelial cells. In the present study, we used the SW system to analyze the expression of IGFs and IGFRs. We demonstrate that IGF2 expression in mesenchymal cells was increased by SW. IGF1R transduces a signal; however, IGF2R does not transduce a signal. Recombinant IGF2 induces IGF1R and IGF2R expression in epithelial cells. IGF1R expression is increased by SW; however, IGF2R expression did not increase by SW. Thus, IGF2 signaling works effectively in SW. These results suggest that IGF signaling acts through the collagen membrane on the interaction between the epithelium and mesenchyme. In SW, other cytokines may be suppressed to induce IGF2R induction. Our results suggest that IGF2 may play a role in tooth differentiation

Rethinking cultural diversity in the UK film sector:practices in community filmmaking

© The Author(s) 2017. Academic, policy and industry debates have tended to focus on the mainstream film sector when discussing cultural diversity. One of the persistent challenges for the sector has been how to diversify cultural representation and participation. This article suggests that participatory modes of community filmmaking make an important contribution to cultural diversity. Drawing on an evidence base derived from qualitative research conducted in three English regions, the article shifts the spotlight away from the mainstream and onto the margins of the film sector in order to explore more ‘bottom-up’ approaches to cultural diversity. It examines how community filmmakers interpret and engage with questions of cultural diversity and how this connects to the participatory and business practices that they adopt. The findings highlight the significance of processes of practice in how mediated cultural diversity manifests itself and the value of community filmmaking in contributing to wider cultural diversity debates and practices.The authors thank the Arts and Humanities Research Council (UK) for funding the ‘Community Filmmaking and Cultural Diversity: Practice, Innovation and Policy project’ (2013–2014)