Pyroclastic density currents (PDC) of the 16-17 August 2006 eruptions of Tungurahua volcano, Ecuador: Geophysical registry and characteristics

Tungurahua, located in the Eastern Cordillera of the Ecuadorian Andes, is a 5023 m-high active volcano, notable for its extreme relief (3200 m), steep sides, and frequent eruptive cycles. From 1999 until 2006 Tungurahua experienced short periods of low to moderate strombolian activity, characterized by fire fountaining, explosions, frequent ash falls and debris flows, and no PDC events. Without warning, Tungurahua initiated PDC activity on 15–16 July 2006, which became more intense on the night of 16–17 August 2006, which is the focus of this study. Continuous monitoring of Tungurahua has employed seismic (both short period and broadband (BB) instruments), SO2 gas emission (COSPEC and DOAS), and geodetic methods (EDM, tilt meters, and GPS), in addition to thermal imagery (airborne and ground-based). Acoustic flow monitors (AFM) installed to monitor lahar activity were important for detecting PDC events. Acoustic signals were monitored at Riobamba, 40 km to the SW, as well as by infrasound sensors at Tungurahua's BB seismic stations. Based on geophysical parameters, visual observations, and PDC deposit characteristics, four phases of distinct eruptive activity are recognized during the 16–17 August episode. Phase I (08H37 to 21H13 of 16 Aug.) (local time) experienced low to moderate strombolian activity with occasional high energy impulsive bursts and small PDC. Phase II (21H13-16 Aug. to 00H12-17 Aug.) was characterized by a number of discrete events with high amplitude seismo-acoustic signals, followed by the generation of larger PDC that overran monitoring stations and had velocities of 30–33 m/s. After midnight, Phase III (00H12 to 01H14) saw an intense period of unrelenting eruptive activity corresponding to the episode's greatest energy release. It was characterized by subplinian activity accompanied by a series of high energy outbursts and constant low frequency jetting that together formed a continuous plume. It was during this phase that the largest PDC were produced, reaching the surrounding river valleys. Phase IV (after 01H14) followed the cessation of the paroxysmal eruption, but witnessed many granular PDC generated by degassed lava spill outs from the crater that developed lobe and channel morphology on the cone's lower flanks. Hours later a blocky lava flow issued from the crater. During these episodes, more than 30 PDC events were detected, the majority being small flows that remained high on the cone. The two largest PDC occurred after midnight, probably generated by fountain collapse. Their descent down the cone's upper steep flanks (~ 28°) and 2.4 km in length favored air entrainment, resulting in PDC with greater fluidity. These flows had volumes of 9 to 17 × 106 m3 and produced widespread, but relatively thin (1–2 m thick) normally-graded deposits at their distal ends. The character and evolution of the PDC activity apparently reflect decreasing volatile contents of the magma and a diminishing magma supply

The retrieval of fingerprint friction ridge detail from elephant ivory using reduced-scale magnetic and non-magnetic powdering materials

An evaluation of reduced-size particle powdering methods for the recovery of usable fingermark ridge detail from elephant ivory is presented herein for the first time as a practical and cost-effective tool in forensic analysis. Of two reduced-size powder material types tested, powders with particle sizes≤40μm offered better chances of recovering ridge detail from unpolished ivory in comparison to a conventional powder material. The quality of developed ridge detail of these powders was also assessed for comparison and automated search suitability. Powder materials and the enhanced ridge detail on ivory were analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy and interactions between their constituents and the ivory discussed. The effect of ageing on the quality of ridge detail recovered showed that the best quality was obtained within 1week. However, some ridge detail could still be developed up to 28days after deposition. Cyanoacrylate and fluorescently-labelled cyanoacrylate fuming of ridge detail on ivory was explored and was less effective than reduced-scale powdering in general. This research contributes to the understanding and potential application of smaller scale powdering materials for the development of ridge detail on hard, semi-porous biological material typically seized in wildlife-related crimes

Aquatic community response to volcanic eruptions on the Ecuadorian Andean flank: evidence from the palaeoecological record

Aquatic ecosystems in the tropical Andes are under increasing pressure from human modification of the landscape (deforestation and dams) and climatic change (increase of extreme events and 1.5 °C on average temperatures are projected for AD 2100). However, the resilience of these ecosystems to perturbations is poorly understood. Here we use a multi-proxy palaeoecological approach to assess the response of aquatic ecosystems to a major mechanism for natural disturbance, volcanic ash deposition. Specifically, we present data from two Neotropical lakes located on the eastern Andean flank of Ecuador. Laguna Pindo (1°27.132′S–78°04.847′W) is a tectonically formed closed basin surrounded by a dense mid-elevation forest, whereas Laguna Baños (0°19.328′S–78°09.175′W) is a glacially formed lake with an inflow and outflow in high Andean Páramo grasslands. In each lake we examined the dynamics of chironomids and other aquatic and semi-aquatic organisms to explore the effect of thick (> 5 cm) volcanic deposits on the aquatic communities in these two systems with different catchment features. In both lakes past volcanic ash deposition was evident from four large tephras dated to c.850 cal year BP (Pindo), and 4600, 3600 and 1500 cal year BP (Baños). Examination of the chironomid and aquatic assemblages before and after the ash depositions revealed no shift in composition at Pindo, but a major change at Baños occurred after the last event around 1500 cal year BP. Chironomids at Baños changed from an assemblage dominated by Pseudochironomus and Polypedilum nubifer-type to Cricotopus/Paratrichocladius type-II, and such a dominance lasted for approximately 380 years. We suggest that, despite potential changes in the water chemistry, the major effect on the chironomid community resulted from the thickness of the tephra being deposited, which acted to shallow the water body beyond a depth threshold. Changes in the aquatic flora and fauna at the base of the trophic chain can promote cascade effects that may deteriorate the ecosystem, especially when already influenced by human activities, such as deforestation and dams, which is frequent in the high Andes

Using technology to deliver cancer follow-up : a systematic review

Peer reviewedPublisher PD

Minsky machines and algorithmic problems

This is a survey of using Minsky machines to study algorithmic problems in semigroups, groups and other algebraic systems.Comment: 19 page

Challenges to conducting research with older people living in nursing homes

<p>Abstract</p> <p>Background</p> <p>Although older people are increasingly cared for in nursing homes towards the end of life, there is a dearth of research exploring the views of residents. There are however, a number of challenges and methodological issues involved in doing this. The aim of this paper is to discuss some of these, along with residents' views on taking part in a study of the perceptions of dignity of older people in care homes and make recommendations for future research in these settings.</p> <p>Methods</p> <p>Qualitative interviews were used to obtain the views on maintaining dignity of 18 people aged 75 years and over, living in two private nursing homes in South East London. Detailed field notes on experiences of recruiting and interviewing participants were kept.</p> <p>Results</p> <p>Challenges included taking informed consent (completing reply slips and having a 'reasonable' understanding of their participation); finding opportunities to conduct interviews; involvement of care home staff and residents' families and trying to maintain privacy during the interviews. Most residents were positive about their participation in the study, however, five had concerns either before or during their interviews. Although 15 residents seemed to feel free to air their views, three seemed reluctant to express their opinions on their care in the home.</p> <p>Conclusion</p> <p>Although we experienced many challenges to conducting this study, they were not insurmountable, and once overcome, allowed this often unheard vulnerable group to express their views, with potential long-term benefits for future delivery of care.</p

Social Roles and Baseline Proxemic Preferences for a Domestic Service Robot

© The Author(s) 2014. This article is published with open access at Springerlink.com. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. The work described in this paper was conducted within the EU Integrated Projects LIREC (LIving with Robots and intEractive Companions, funded by the European Commission under contract numbers FP7 215554, and partly funded by the ACCOMPANY project, a part of the European Union’s Seventh Framework Programme (FP7/2007–2013) under grant agreement n287624The goal of our research is to develop socially acceptable behavior for domestic robots in a setting where a user and the robot are sharing the same physical space and interact with each other in close proximity. Specifically, our research focuses on approach distances and directions in the context of a robot handing over an object to a userPeer reviewe