Laser-induced plasmas in air for pulsed broadband cavity-enhanced absorption spectroscopy

A pulsed laser-induced plasma (LIP) was generated in ambient air inside a high-finesse near-concentric optical cavity. The broadband optical plasma emission was successfully sustained within the cavity and the light leaking from the cavity was used to measure broadband absorption spectra of gaseous azulene through (i) time-dependent cavity ring-down (CRDS), and (ii) intensity-dependent incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) methodologies. Based on the broadband ring-down time of light within the cavity, cavity mirror reflectivities may be calibrated in situ, thus facilitating measurements of absolute absorption coefficients with the intensity-dependent (IBBCEAS) approach. Each of the two spectroscopic approaches are compared in terms of their overall performance and suitability to the experimental requirements. The IBBCEAS approach was found to possess numerous advantages over the CRDS approach in terms of measurement speed, and achievable signal-to-noise ratios and minimum detectable absorption coefficients. However, the IBBCEAS approach is limited by the presence of an artificial offset in the measured absorption that arises due to the absorption of light occurring between LIP formation and the commencement of data collection. This delay prior to data collection is necessitated by the non-Lambert-Beer conditions during plasma equilibration. For the given experimental conditions, the cavity output typically takes ~ 1.5 μs to begin mono-exponential decay. The time-dependence of the cavity output intensity was also investigated. Light propagating within the cavity is subject to direct absorption by the intra-cavity LIP, and a lensing effect (f ≈ −3.1 cm) by the LIP as a result of a localised nonlinear refractive index change induced by the high temperatures and strong electric fields associated with the LIP. This time-dependence was observed to be dependent on both the mirror separation and the pulse duration of the LIP formation laser. These dependencies come about as a consequence of the LIP lensing temporarily affecting both the cavity stability and the imaging of the light that is output from the cavity, with both of these aspects being dependent on the cavity geometry. In the case of fs-lasers, the increased pulse power density expectedly yields a more significant lensing effect when compared to LIP formation with ns-pulsed lasers

Time- and intensity-dependent broadband cavity-enhanced absorption spectroscopy with pulsed intra-cavity laser-induced plasmas

A pulsed laser-induced plasma (LIP) was generated in ambient air inside a high-finesse (F ≈ 5200) near-concentric optical cavity. The optical plasma emission was successfully trapped and sustained by the cavity, manifested by ring-down times in excess of 4 μs indicating effective mirror reflectivities of ∼0.9994. The light leaking from the cavity was used to measure broadband absorption spectra of gaseous azulene under ambient air conditions between 580 and 645 nm, employing (i) intensity-dependent cavity-enhanced, and (ii) time-dependent cavity-ring down methodologies. Minimum detectable absorption coefficients of 4.7 × 10−8 cm−1 and 7.4 × 10−8 cm−1 were achieved for the respective approaches. The two approaches were compared and implications of pulsed excitation for gated intensity-dependent measurements were discussed

Fluctuating magnetic moments in liquid metals

We re-analyze literature data on neutron scattering by liquid metals to show that non-magnetic liquid metals possess a magnetic moment that fluctuates on a picosecond time scale. This time scale follows the motion of the cage-diffusion process in which an ion rattles around in the cage formed by its neighbors. We find that these fluctuating magnetic moments are present in liquid Hg, Al, Ga and Pb, and possibly also in the alkali metals.Comment: 17 pages, 5 figures, submitted to PR

Using Online Role-playing Games for Entrepreneurship Training

This edited collection of chapters explores the application, potential and challenges of game-based learning and gamification across multiple disciplines and sectors, including psychology, education, business, history, languages and the ..

Reconnaissance Survey of the Irish Continental Shelf/Shelf Edge - Atlantic Irish Regional Survey (AIRS) 1996: A GLORIA Survey of the Irish Continental Margin

The Atlantic Irish Regional Survey (AIRS96) sidescan sonar survey was carried out in August 1996. Covering an area of 200,000 sq.km it represented the largest reconnaissance seabed survey of the Irish Continental Shelf region. It covered both margins, together with much of the basin floor, of the Irish sector of the Rockall Trough and extended into the northern part of the Porcupine Seabight. The objectives of this project were two fold: 1. Strategic: •to undertake, for the first time a preliminary reconnaissance survey of the Irish Continental Shelf/Shelf Edge, •to establish a strategic database on Shelf/Slope Edge conditions, •to provide training and experience to Irish researchers in state of the art marine surveying equipment (GLORIA) and data processing. 2. Scientific: •to document slope stability and mass wasting features on the margins of the Rockall Trough, •to map, where possible, occurrences of deep water carbonate mounds, •to investigate the sediment erosional, transport and depositional mechanisms that have shaped the present morphology of the region. The survey revealed a range of sedimentary features across the steep (i.e. >6º slope) margins and the basin floor in the Rockall Trough. Four classes of sedimentary feature are recognised: (1) mass failure, (2) canyon systems, (3) sediment fans, and (4) sediment drifts. The western margin is characterised by large-scale downslope mass movement features. The western and central parts of the basin floor in the Rockall Trough contain the Feni Sediment Ridge, a large Miocene-Recent contourite sediment accumulation draped by large sediment waves trending sub-parallel to the dominant modern current pattern. A large-scale downslope mass failure feature is recognised across 14,000 sq.km of the northeastern margin of the Rockall Trough. Smaller slides and slumps occur along the eastern margin in association with more prevalent canyon, channel and fan systems. A cluster of carbonate mounds was imaged in the northern part of the Porcupine Seabight. These represent part of one of the most extensive suites of deep-water carbonate mounds in the Atlantic Margin and are currently the subject of a number of new EU-funded research projects. Strong northward-directed bottom currents along the eastern margin are suggested to erode, circulate and re-deposit sediment on the basin floor and on the western margin of the Rockall Trough. The main terrigenous sedimentary input was from the Irish Mainland Shelf. A broad interplay of alongslope and downslope sediment transport processes shaped the morphology of the Rockall Trough, while tectonically-driven basin subsidence, Quaternary glaciations and glacio-eustatic sea-level fluctuations also influenced the overall sedimentation pattern in the Rockall Trough.Funder: Marine Institut

An approach to evaluating the user experience of serious games

The use of serious games to support learning continues to expand across a range of educational and training settings. Hence, a need exists to understand more fully how users experience such games. This study seeks to describe and assess an approach to the evaluation of user-experience applied within the context of a specific serious game developed to address the training needs of people working in social enterprises. Drawing on an extensive literature review, the development of a survey instrument to capture the multi-dimensional nature of user-experience is explained as is the evaluation process employed. Findings from surveys of individuals working in social enterprises are analysed and discussed. The results demonstrate the value of the proposed method of user-experience evaluation. Recommendations for practice and further research are outlined, identifying in particular the importance of qualitative insights in the evaluation process and the need for greater understanding of the inter-relationships between the various dimensions and attributes of user-experience in serious games

Active Hydrothermal Features as Tourist Attractions

Tourists are looking increasingly for adventurous experiences by exploring unusual and interesting landscapes. Active volcanic and hydrothermal landscapes and their remarkable manifestations of geysers, fumaroles and boiling mud ponds are some of the surface features that fascinate visitors of National Parks, Geoparks and World Heritage areas worldwide. The uniqueness of hydrothermal activity based on volcanism has provided popular tourist attractions in many countries for several thousand years. The Romans for example have used hydrothermal springs on the Italian island Ischia and visited the Campi Flegrei for recreational purposes. In Iceland the original Geysir already attracted international visitors over 150 years ago, who came to observe this spectacular hydrothermal phenomenon. In Greece and Turkey volcanic hot springs have historically provided attractive destinations, as well as in New Zealand, Japan and the Americas. The fact that locations with hydrothermal activity based on active volcanism have acquired various forms of protected site status, adds a further dimension to their attraction and demonstrates a significant contribution to sustainable and nature based tourism. Countries such as Iceland, New Zealand and Japan have a long tradition of using hydrothermal activity in its various forms to offer tourists a unique natural experience. These environments however are also known for their unpredictable and potentially hostile nature, as the use of hydrothermal features as a natural resource for tourism does harbour certain risks with the potential to affect human health and safety. Hydrothermal systems have erupted in the past, thereby causing the destruction of their immediate environment. Depending on the level of magnitude explosions of super heated water and steam mixed with fractured rocks and hot mud can be violent enough to create craters varying in size from a few metres to several hundred metres in diameter. Apart from unexpected eruptions of hydrothermal vents with the potential to cause thermal burns, further risk factors include seismic activity such as earthquakes, lethal gas emissions of hydrogen sulphide (H2S) as well as ground instability through hydrothermal alteration. While it is essential to prevent injuries to tourists the management of hydrothermal hazards remains problematic. Precursory signs are not well understood by the general public and the communication of imminent danger is frequently unachievable. As a consequence serious thought needs to be given to the risk factors and the potential danger of areas in the proximity of active hydrothermal manifestations such as extreme hot springs and geysers. To improve the safety standards in hydrothermal landscapes that are used as main features in tourism, strategic guidelines for best practice management must cover ALL active volcanic and hydrothermal areas. This chapter looks at management issues at hydrothermal destinations with special consideration of areas where these unique features are integrated as tourist attractions. Examples from destinations traditionally based on active volcanic and hydrothermal phenomena are presented as case studies to highlight the risk management processes in individual countries. Potential hazards in volcanic and hydrothermal areas are assessed with a focus on the prevention of accidents and injuries to tourists

Elderly with Autism: Executive Functions and Memory

Cognitive autism research is mainly focusing on children and young adults even though we know that autism is a life-long disorder and that healthy aging already has a strong impact on cognitive functioning. We compared the neuropsychological profile of 23 individuals with autism and 23 healthy controls (age range 51–83 years). Deficits were observed in attention, working memory, and fluency. Aging had a smaller impact on fluency in the high functioning autism (HFA) group than in the control group, while aging had a more profound effect on visual memory performance in the HFA group. Hence, we provide novel evidence that elderly with HFA have subtle neuropsychological deficits and that the developmental trajectories differ between elderly with and without HFA in particular cognitive domains

Оптимизация конструкции захвата для детали «Барабан»

Грузозахватные приспособления обычно применяются при производстве работ по подъему и перемещению грузов с применением грузоподъемных машин. Использование приспособлений позволяет реализовать максимальное удобство и безопасность производственного процесса. Грузозахватные приспособления конструируются для определенного этапа технологического процесса, для конкретного изделия. При проектировании таких приспособлений необходимо учитывать основные показатели оптимальности конструкции: прочность, надежность, простота, удобство и безопасность при эксплуатации, эргономичность. Кроме того, нужно стремиться к наименьшей массе и, соответственно, металлоемкости захвата. Конструкция грузозахватного приспособления, в основном, будет зависеть от назначенных технологом поверхностей, за которые можно крепиться и от максимальной высоты подъема крюка крана. В статье описана задача по конструированию захвата для детали «Барабан¬ в новом технологическом процессе. Рассмотрена конструкция существующего захвата, взятого за прототип. Приведен анализ различных вариантов конструктивных решений, созданных в процессе проектирования. Выбран вариант конструкции захвата, который в наибольшей степени соответствует требованиям технического задания. Конструкция этого модернизированного приспособления представляет собой захват с тремя лапами, удерживающими деталь, и подвес в виде траверсы. Разработанная конструкторская документация утверждена производством и отделом промышленной безопасности