Economics of Tourism and Transport: An Introduction

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Investigating potential icequakes at Llaima volcano, Chile

Glacially- and magmatically-derived seismic events have been noted to heavily overlap in their characteristics, thus there exists the potential for false-alarms or missed warnings at ice-covered volcanoes. Here we present the first study to specifically investigate icequakes at an ice-covered volcano in Southern Chile. Two months of broadband seismic data collected at Llaima volcano in 2015 were analyzed in order to quantify, characterize, and locate potential glacially-derived seismic events at one of the most active ice-covered volcanoes in the region. We find over 1,000 repeating seismic events across 11 families, the largest of which contains 397 events. Approximate locations and characteristics of the largest families lead us to conclude that these events were derived from persistent stick-slip motion along the ice-rock interface at the base of a glacier near the volcano summit. These results have implications for future seismic monitoring at Llaima volcano and other ice-covered active volcanoes in the region

Persistent shallow micro-seismicity at Llaima volcano, Chile, with implications for long-term monitoring

Identifying the source mechanisms of low-frequency earthquakes at ice-covered volcanoes can be challenging due to overlapping characteristics of glacially and magmatically derived seismicity. Here we present an analysis of two months of seismic data from Llaima volcano, Chile, recorded by the permanent monitoring network in 2019. We find over 2000 repeating low-frequency events split across 82 families, the largest of which contains over 200 events. Estimated locations for the largest families indicate shallow sources directly beneath or near the edge of glaciers around the summit vent. These low-frequency earthquakes are part of an annual cycle in activity at the volcano that is strongly correlated with variations in atmospheric temperature, leading us to conclude that meltwater from ice and snow strongly affects the seismic source mechanisms related to glacier dynamics and shallow volcanic processes. The results presented here should inform future assessments of eruptive potential at Llaima volcano, as well as other ice-covered volcanoes in Chile and worldwide

Electron energy loss and induced photon emission in photonic crystals

The interaction of a fast electron with a photonic crystal is investigated by solving the Maxwell equations exactly for the external field provided by the electron in the presence of the crystal. The energy loss is obtained from the retarding force exerted on the electron by the induced electric field. The features of the energy loss spectra are shown to be related to the photonic band structure of the crystal. Two different regimes are discussed: for small lattice constants $a$ relative to the wavelength of the associated electron excitations $\lambda$, an effective medium theory can be used to describe the material; however, for $a\sim\lambda$ the photonic band structure plays an important role. Special attention is paid to the frequency gap regions in the latter case.Comment: 12 pages, 7 figure

The Muonium Atom as a Probe of Physics beyond the Standard Model

The observed interactions between particles are not fully explained in the successful theoretical description of the standard model to date. Due to the close confinement of the bound state muonium ($M = \mu^+ e^-$) can be used as an ideal probe of quantum electrodynamics and weak interaction and also for a search for additional interactions between leptons. Of special interest is the lepton number violating process of sponteanous conversion of muonium to antimuonium.Comment: 15 pages,6 figure

Anti-tumour necrosis factor therapy for early-stage Dupuytren's disease (RIDD): a phase 2b, randomised, double-blind, placebo-controlled trial

Background Dupuytren's disease is a common fibrotic condition that causes the fingers to flex irreversibly into the palm. Treatments for late-stage disease all have limitations, and there is no approved treatment for early-stage disease. We identified tumour necrosis factor as a therapeutic target in Dupuytren's disease, and in a dose ranging trial found 40 mg adalimumab in 0·4 mL to be most efficacious. Here we aimed to assess the effects of intranodular injection of adalimumab in early-stage disease. Methods In this phase 2b, randomised, double-blind, placebo-controlled trial adults with early-stage Dupuytren's disease and an established clinically distinct nodule with a clear history of progression in the preceding 6 months were recruited from two clinical centres in the UK and were randomly assigned 1:1 to receive four injections of adalimumab or saline every 3 months. Participants and assessors were masked. The primary outcome was nodule hardness measured with a durometer at 12 months. Data were analysed by linear mixed effects regression models in the intention-to-treat population with multiple imputation for missing primary outcome data. The trial is registered at the ISRCTN registry, ISRCTN 27786905 and is complete. Findings Between Feb 17, 2017, and Jan 11, 2019, 284 participants were screened in the UK and 140 were enrolled. 47 (34%) participants were female and 93 (66%) were male. Mean age of participants was 59·7 years (SD 10·0). Primary outcome data were available from 113 participants. Nodule hardness was lower (−4·6 AU [95% CI −7·1 to −2·2], p=0·0002) in the adalimumab compared with the saline group at 12 months. There were no related serious adverse events; the most common adverse events were minor injection site reactions. Interpretation Intranodular injections of adalimumab in participants with early-stage Dupuytren's disease resulted in softening and reduction in size of the nodules. Longer follow-up would be required to assess the effect of tumour necrosis factor inhibition on disease progression, extension deficit and hand function. Funding Health Innovation Challenge Fund (Wellcome Trust, Department of Health) and 180 Life Sciences

Demystifying an unidentified EGRET source by VHE gamma-ray observations

In a novel approach in observational high-energy gamma-ray astronomy, observations carried out by imaging atmospheric Cherenkov telescopes provide necessary templates to pinpoint the nature of intriguing, yet unidentified EGRET gamma-ray sources. Using GeV-photons detected by CGRO EGRET and taking advantage of high spatial resolution images from H.E.S.S. observations, we were able to shed new light on the EGRET observed gamma-ray emission in the Kookaburra complex, whose previous coverage in the literature is somewhat contradictory. 3EGJ1420-6038 very likely accounts for two GeV gamma-ray sources (E>1 GeV), both in positional coincidence with the recently reported pulsar wind nebulae (PWN) by HESS in the Kookaburra/Rabbit complex. PWN associations at VHE energies, supported by accumulating evidence from observations in the radio and X-ray band, are indicative for the PSR/plerionic origin of spatially coincident, but still unidentified Galactic gamma-ray sources from EGRET. This not only supports the already suggested connection between variable, but unidentified low-latitude gamma-ray sources with pulsar wind nebulae (3EGJ1420-6038 has been suggested as PWN candidate previoulsy), it also documents the ability of resolving apparently confused EGRET sources by connecting the GeV emission as measured from a large-aperture space-based gamma-ray instrument with narrow field-of-view but superior spatial resolution observations by ground-based atmospheric Cherenkov telescopes, a very promising identification technique for achieving convincing individual source identifications in the era of GLAST-LAT.Comment: 4 pages, 5 figures, Accepted for publication in Astrophysics and Space Science, Proc. of "The Multi-Messenger Approach to High-Energy Gamma-ray Sources (Third Workshop on the Nature of Unidentified High-Energy Sources)", Barcelona, July 4-7, 2006, one typo correcte

Transverse Momentum Dependent Parton Distribution/Fragmentation Functions at an Electron-Ion Collider

We present a summary of a recent workshop held at Duke University on Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions. The transverse momentum dependent parton distribution functions (TMDs), parton-to-hadron fragmentation functions, and multi-parton correlation functions, were discussed extensively at the Duke workshop. In this paper, we summarize first the theoretical issues concerning the study of partonic structure of hadrons at a future electron-ion collider (EIC) with emphasis on the TMDs. We then present simulation results on experimental studies of TMDs through measurements of single spin asymmetries (SSA) from semi-inclusive deep-inelastic scattering (SIDIS) processes with an EIC, and discuss the requirement of the detector for SIDIS measurements. The dynamics of parton correlations in the nucleon is further explored via a study of SSA in D (`D) production at large transverse momenta with the aim of accessing the unexplored tri-gluon correlation functions. The workshop participants identified the SSA measurements in SIDIS as a golden program to study TMDs in both the sea and valence quark regions and to study the role of gluons, with the Sivers asymmetry measurements as examples. Such measurements will lead to major advancement in our understanding of TMDs in the valence quark region, and more importantly also allow for the investigation of TMDs in the sea quark region along with a study of their evolution.Comment: 44 pages 23 figures, summary of Duke EIC workshop on TMDs accepted by EPJ

Influence of flow containment and substrate entrainment upon sandy hybrid event beds containing a co-genetic mud-clast-rich division

Individual sandstone beds containing a co-genetic mud-clast-rich (MCR) division are being increasingly described from the distal reaches of many deep-water fan systems. These deposits, termed hybrid event beds, are considered to record a flow whose composition and rheology changed significantly to become increasingly more argillaceous (clay-rich), MCR and turbulence-suppressed during the deposition of a single event bed. Studies of confined systems, in which gravity flows were affected by confining sea-floor topography, have documented similar deposits recording turbulence suppression in proximity to confining sea-floor topography (e.g., basin margins). In new research from a confined, contained system from the Castagnola Basin of NW Italy, lateral transects of individual sandstone beds 5 km in extent show that individual sandstone beds contain a co-genetic MCR division which is often; 1) extensive across the basin rather than localised adjacent to confining topography; 2) exhibits rapid, significant and repeated variation in depositional character over short length scales (tens to hundreds of metres), specifically in terms of the thickness of co-genetic MCR divisions and the size and abundance of clasts contained within them; and 3) exhibits variation in depositional character over larger length scales (> 1 km) which is non-systematic in relation to palaeoflow direction or increasing proximity towards the counter slope of the downstream confining northern basin margin. A suite of factors within the Castagnola Basin is thought to have resulted in the deposition of these co-genetic MCR divisions whose thickness and distribution are less predictable in relation to confining sea-floor topography than those described from other confined uncontained settings. Specific factors include; 1) recent and voluminous entrainment of muddy substrate at seemingly random locations across the basin floor and their support and transport within a high sediment concentration gravity flow; and 2) containment (ponding) of gravity flows within a confined basin, which is thought to have established extensive and complex three dimensional flow dynamics across the basin following flow interaction with multiple basin margins. This research highlights the role of entrainment of muddy substrate and subsequent transport processes of muddy substrate for developing co-genetic MCR divisions, as well as the importance of understanding the degree of containment depositional systems experienced when considering the spatial distribution of depositional facies, and thus reservoir quality, in topographically complex settings

Can occupational therapist-led home environmental assessment prevent falls in older people? A modified cohort randomised controlled trial protocol

INTRODUCTION: Falls and fall-related injuries are a serious cause of morbidity and cost to society. Environmental hazards are implicated as a major contributor to falls among older people. A recent Cochrane review found an environmental assessment, undertaken by an occupational therapist, to be an effective approach to reducing falls. However, none of the trials included a cost-effectiveness evaluation in the UK setting. This protocol describes a large multicentre trial investigating the clinical and cost-effectiveness of environmental assessment and modification within the home with the aim of preventing falls in older people. METHODS AND ANALYSIS: A two-arm, modified cohort randomised controlled trial, conducted within England, with 1299 community-dwelling participants aged 65 years and above, who are at an increased risk of falls. Participants will be randomised 2:1 to receive either usual care or home assessment and modification. The primary outcome is rate of falls (falls/person/time) over 12 months assessed by monthly patient self-report falls calendars. Secondary self-reported outcome measures include: the proportion of single and multiple fallers, time to first fall over a 12-month period, quality of life (EuroQoL EQ-5D-5L) and health service utilisation at 4, 8 and 12 months. A nested qualitative study will examine the feasibility of providing the intervention and explore barriers, facilitators, workload implications and readiness to employ these interventions into routine practice. An economic evaluation will assess value for money in terms of cost per fall averted. ETHICS AND DISSEMINATION: This study protocol (including the original application and subsequent amendments) received a favourable ethical opinion from National Health Service West of Scotland REC 3. The trial results will be published in peer-reviewed journals and at conference presentations. A summary of the findings will be sent to participants. TRIAL REGISTRATION NUMBER: ISRCTN22202133; Pre-results