Numerical Study of Wave Slamming on an Oscillating Flap

Bottom hinged Oscillating Wave Surge Converters (OWSCs) are efficient devices for extracting power from ocean waves. There is limited knowledge about wave slamming on such devices. This paper deals with numerical studies of wave slamming on an oscillating flap to investigate the mechanism of slamming events. In our model, the Navier–Stokes equations are discretized using the Finite Volume method with the Volume of Fluid (VOF) approach for interface capturing. Waves are generated by a flaptype wave maker in the numerical wave tank, and the dynamic mesh method is applied to model the motion of the oscillating flap. Basic mesh and time step refinement studies are performed. The flow characteristics in a slamming event are analysed based on numerical results. Various simulations with different flap densities, water depths and wave amplitudes are performed for a better understanding of the slamming.

Skin-reducing mastectomy and one-stage implant reconstruction with a myodermal flap: A safe and effective technique in risk-reducing and therapeutic mastectomy

Introduction: Immediate reconstruction following mastectomy for breast cancer has been shown to be oncologically safe and associated with improved psychosocial outcomes for patients. Bostwick described a technique for one-stage implant based reconstruction, combining skin-sparing mastectomy with concurrent reduction of the skin envelope. This report reviews the experience of a single centre using skin-reducing mastectomy and one-stage implant reconstruction in both early stage breast cancer and risk-reducing mastectomy, with specific reference to frequency of complications, implant loss and oncological outcomes.

Methods and results: A retrospective review was undertaken to identify women who had undergone skin-reducing mastectomy and one-stage implant reconstruction using a de-epithelialised dermal flap, between October 2008 and October 2012. One hundred and four consecutive mastectomies, with reconstruction, were performed by two surgeons on 64 patients. No complications were seen in 43.8% of patients. At three months, four implants were lost (3.8% of breast reconstructions, 6.3% of patients), due to either peri-implant infection or mastectomy skin flap necrosis. One patient required unplanned return to theatre for evacuation of a haematoma. Minor mastectomy skin flap necrosis was seen in 10 breasts (9.6% of reconstructed breasts) and superficial wound infection in 8 breasts (7.7% of reconstructed breasts). All of these complications were managed conservatively and none required operative intervention. At a median follow up of 35 months (4-53 months) there had been one episode of ipsilateral axillary nodal recurrence.

Conclusion: One-stage implant reconstruction using a myo-dermal flap technique following skin-reducing mastectomy is safe and should be considered in selected patients. Most complications are minor and will resolve with conservative management. Major complications such as implant failure or immediate reoperation, were relatively uncommon (6.3% patients, 3.8% of reconstructed breasts). Early follow-up suggests that oncological outcomes are satisfactory, but longer follow-up is required to substantiate this. (C) 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Wave loads on the foundation of a bottom-hinged modular flap structure

Large loads result in expensive foundations which are a substantial proportion of the capital cost of flap-type Wave Energy Converters (WECs). Devices such as Oyster 800, currently deployed at the European Marine Energy Centre (EMEC), comprise a single flap for the full width of the machine. Splitting a flap-type device into smaller vertical flap modules, to make a ‘modular-flap’, might reduce the total foundation loads, whilst still providing acceptable performance in terms of energy conversion.
This paper investigates the foundation loads of an undamped modular-flap device, comparing them to those for a rigid flap of an equivalent width. Physical modelling in a wave tank is used, with loads recorded using a six degree of freedom (DoF) load cell. Both fatigue and extreme loading analysis was conducted. The rotations of the flaps were also recorded, using a motion-tracking system.

High-precision ultra-distal Holocene tephrochronology in North America

Far-travelled volcanic ashes (tephras) from Holocene eruptions in Alaska and the Pacific northwest have been traced to the easternmost extent of North America, providing the basis for a new high-precision geochronological framework throughout the continent through tephrochronology (the dating and correlation of tephra isochrons in sedimentary records). The reported isochrons are geochemically distinct, with seven correlated to documented sources in Alaska and the Cascades, including the Mazama ash from Oregon (w7600 years old) and the eastern lobe of the White River Ash from Alaska (~1150 years old). These findings mark the beginning of a tephrochronological framework of enhanced precision across North America, with applications in palaeoclimate, surface process and archaeological studies. The particle travel distances involved (up tow7000 km) also demonstrate the potential for continent-wide or trans-Atlantic socio-economic disruption from similar future eruptions.

Distal Deposition of Tephra from the Eyjafjallajökull 2010 Summit Eruption

The 2010 Eyjafjallajökull lasted 39 days and had 4 different phases, of which the first and third (14–18 April and 5–6 May) were most intense. Most of this period was dominated by winds with a northerly component that carried tephra toward Europe, where it was deposited in a number of locations and was sampled by rain gauges or buckets, surface swabs, sticky-tape samples and air filtering. In the UK, tephra was collected from each of the Phases 1–3 with a combined range of latitudes spanning the length of the country. The modal grain size of tephra in the rain gauge samples was 25 um, but the largest grains were 100 um in diameter and highly vesicular. The mass loading was equivalent to 8–218 shards cm2, which is comparable to tephra layers from much larger past eruptions. Falling tephra was collected on sticky tape in the English Midlands on 19, 20 and 21st April (Phase 2), and was dominated by aggregate clasts (mean diameter 85 um, component grains <10 um). SEM-EDS spectra for aggregate grains contained an extra peak for sulphur, when compared to control samples from the volcano, indicating that they were cemented by sulphur-rich minerals e.g. gypsum (CaSO4⋅H2O). Air quality monitoring stations did not record fluctuations in hourly PM10 concentrations outside the normal range of variability during the eruption, but there was a small increase in 24-hour running mean concentration from 21–24 April (Phase 2). Deposition of tephra from Phase 2 in the UK indicates that transport of tephra from Iceland is possible even for small eruption plumes given suitable wind conditions. The presence of relatively coarse grains adds uncertainty to concentration estimates from air quality sensors, which are most sensitive to grain sizes <10 um. Elsewhere, tephra was collected from roofs and vehicles in the Faroe Islands (mean grain size 40 um, but 100 um common), from rainwater in Bergen in Norway (23–91 um) and in air filters in Budapest, Hungary (2–6 um). A map is presented summarizing these and other recently published examples of distal tephra deposition from the Eyjafjallajökull eruption. It demonstrates that most tephra deposited on mainland Europe was produced in the highly explosive Phase 1 and was carried there in 2–3 days.

The taphonomy of Last Glacial–Interglacial Transition (LGIT) distal volcanic ash in small Scottish lakes

An extensive micro-tephrostratigraphic survey of three small lakes in the Scottish Inner Hebrides was conducted encompassing the Last Glacial–Interglacial Transition (LGIT). The lakes are highly contrasting in terms of lake area to catchment ratio, the presence or absence of stream inlets draining the catchment, and in the complexity of the catchment drainage network. A suite of distal Icelandic volcanic ashes was consistently detected in all three lakes, with three, namely Penifiler Tephra, Vedde Ash and Ashik Tephra, being common to all the lakes. These ashes were chosen to examine the taphonomic intercomparability of ash location and concentration among the lakes. Findings reveal that the part played by catchment inlets in determining ash concentration and within-basin location applies to microtephra layers as much as it does in studies of macrotephra layer thickness. The position of ash concentration maxima is also shown to vary significantly for different LGIT periods and may be a consequence of lake-level changes, especially during the early Holocene. High-resolution stratigraphic analysis through the Vedde Ash visible macrotephra at Loch Ashik reveals a high degree of complexity in taphonomic behaviour between the different geochemical components, with possible implications for the correct interpretation of the isochron position. The detection of multiple intact ash isochrons and the taphonomic processes responsible for their deposition should prove useful in future tephrostratigraphic surveys, as well as having applications within other palaeolimnological disciplines.

Distal volcanic ash layers in the Lateglacial Interstadial (GI-1): problems of stratigraphic discrimination

A new Icelandic ash layer has been detected in mid-Interstadial sediments in a number of Scottish Lateglacial sequences and has been named the Penifiler Tephra. It is rhyolitic in composition and possesses a chemistry, which is similar to the Borrobol Tephra of early Lateglacial Interstadial age, which also occurs in a number of these same sequences. Where the Borrobol Tephra has been identified in these sequences it consistently exhibits a diffuse distribution accompanied in some cases by stratigraphic bimodality. A number of sedimentological and taphonomic factors are considered in order to account for this distribution. One possibility is that these distributions are produced by taphonomic factors. Another possibility is that the Borrobol Tephra may not be the product of a single Icelandic eruption, but of two events closely spaced in time. In at least two of the sequences investigated in this study, basaltic shards were found in association with the Penifiler and Borrobol tephras, suggesting either a basaltic phase associated with these eruptions, or coincident eruptions from a separate basaltic volcanic centre. The discovery of the new Penifiler Tephra makes a contribution to the regional tephrostratigraphic framework, and provides an additional isochron for assessing the synchroneity of palaeoenvironmental changes during the Interstadial. The true stratigraphic nature and age of the Borrobol Tephra, however, remains unresolved and, therefore, its use as an isochron is more problematic. The possible occurrence of basaltic populations may strengthen correlations with basaltic tephras recently detected in the NGRIP ice-core.

Three new distal tephras in sediments spanning the Last Glacial-Interglacial Transition in Scotland

Three new microtephras are reported from a number of lake sites from the Inner Hebrides and Scottish mainland. One occurs stratigrapically in the middle of Greenland Interstadial 1 (GI-1) and has been named the Penifiler Tephra. It is rhyolitic and possesses a geochemical signature that is very similar to that of the Borrobol Tephra, which also occurs in three of the sequences reported here, but which lies close to the lower boundary of GI-1. The second occurs stratigraphically in the early Holocene below the Saksunarvatn Ash and is named the Ashik Tephra. This tephra is geochemically bimodal, with a rhyolitic component comparable to the An Druim Tephra that occurs later in the Holocene, and a basaltic component which is similar to the Saksunarvatn Ash. A third tephra occurs stratigraphically above the Saksunarvatn Ash and is provisionally named the Breakish Tephra. The consistent inter-site correlation demonstrated for these new tephras at several sites enhances the regional tephrostratigraphic framework, and increases the potential for correlating palaeoenvironmental events during GI-1 and the early Holocene. However, the occurrence of multiple tephras with similar geochemistry in close stratigraphic and temporal proximity has implications for the rigour with which tephrostratigraphic investigations must be performed.

A new and less destructive laboratory procedure for the physical separation of distal glass tephra shards from sediments

Tephrochronology, a key tool in the correlation of Quaternary sequences, relies on the extraction of tephra shards from sediments for visual identification and high-precision geochemical comparison. A prerequisite for the reliable correlation of tephra layers is that the geochemical composition of glass shards remains unaltered by natural processes (e.g. chemical exchange in the sedimentary environment) and/or by laboratory analytical procedures. However, natural glasses, particularly when in the form of small shards with a high surface to volume ratio, are prone to chemical alteration in both acidic and basic environments. Current techniques for the extraction of distal tephra from sediments involve the ‘cleaning’ of samples in precisely such environments and at elevated temperatures. The acid phase of the ‘cleaning’ process risks alteration of the geochemical signature of the shards, while the basic phase leads to considerable sample loss through dissolution of the silica network. Here, we illustrate the degree of alteration and loss to which distal tephras may be prone, and introduce a less destructive procedure for their extraction. This method is based on stepped heavy liquid flotation and which results in samples of sufficient quality for analysis while preserving their geochemical integrity. In trials, this method out-performed chemical extraction procedures in terms of the number of shards recovered and has resulted in the detection of new tephra layers with low shard concentrations. The implications of this study are highly significant because (i) the current database of distal tephra records and their corresponding geochemical signatures may require refinement and (ii) the record of distal tephras may be incomplete due to sample loss induced by corrosive laboratory procedures. It is therefore vital that less corrosive laboratory procedures are developed to make the detection and classification of distal glass tephra more secure.

Detection of Lateglacial distal tephra layers in the Netherlands

Three distal tephra layers or cryptotephras have been detected within a sedimentary sequence from the Netherlands that spans the last glacial-interglacial transition. Geochemical analyses identify one as the Vedde Ash, which represents the southernmost discovery of this mid-Younger Dryas tephra so far. This tephra was found as a distinct horizon in three different cores sampled within the basin. The remaining two tephras have not been geochemically ‘fingerprinted’, partly due to low concentrations and uneven distributions of shards within the sequences sampled. Nevertheless, there is the potential for tracing these tephra layers throughout the Netherlands and into other parts of continental Europe. Accordingly, the possibilities for precise correlation of Dutch palaeoenvironmental records with other continental, marine and ice-core records from the North Atlantic region are highlighted.

Distal tephrochronology in volcanic regions: Challenges and insights from Kamchatkan lake sediments

Kamchatka is one of the world’s most active volcanic regions and has hosted many explosive eruptions during the Holocene. These eruptions had the potential to disperse tephra over wide areas, forming time-synchronous markers wherever those tephras are found. Recent research in Kamchatka has begun to focus on the geochemical analysis of individual glass shards in order to characterise tephra layers. We have applied this approach to the study of visible tephras from three lakes – one in central and two in northern Kamchatka – with the aim of identifying key tephras and potential issues in the application of distal (>100 km from an active volcano) tephra in volcanically complex regions. In total, 23 tephras from 22 tephra beds have been geochemically analysed, representing products from at least four volcanic systems in Kamchatka. We demonstrate that distal lake sediments in the region can yield reliable tephrostratigraphies, capturing tephra from eruptions that have the greatest potential to disperse volcanic ash beyond the region. We draw attention to issues relating to correlating and distinguishing key marker horizons from the highly active Shiveluch Volcano, namely the need to ensure inter-lab comparability of geochemical data and good chronological control of the proximal and distal tephras. Importantly, we have also extended the known distribution of two key tephra isochrons from the Ksudach volcano. Our work contributes valuable glass geochemical on data several key marker beds that will facilitate future tephra and palaeoenvironmental research within and beyond Kamchatka.

Exceptionally Long Distance Transport of Volcanic Ash: Implications for Stratigraphy, Hazards and the Sourcing of Distal Tephra Deposits

Cryptotephras (tephra not visible to the naked eye) form the foundation of the tephrostratigraphic frameworks used in Europe to date and correlate widely distributed geologic, paleoenvironmental and archaeological records. Pyne-O'Donnell et al. (2012) established the potential for developing a similar crypto-tephrostratigraphy across eastern North America by identifying multiple tephra, including the White River Ash (east; WRAe), St. Helens We and East Lake, in a peat core located in Newfoundland. Following on from this work, several ongoing projects have examined additional peat cores from Michigan, New York State, Maine, Nova Scotia and Newfoundland to build a tephrostratigraphic framework for this region. Using the precedent set by recent research by Jensen et al.(in press) that correlated the Alaskan WRAe to the European cryptotephra AD860B, unknown tephras identified in this work were not necessarily assumed to be from "expected" source areas (e.g. the Cascades). Here we present several examples of the preservation of tephra layers with an intercontinental distribution (i.e. WRAe and Ksudach 1), from relatively small magnitude events (i.e. St. Helens layer T, Mono Crater), and the first example of a Mexican ash in the NE (Volcan Ceboruco, Jala pumice). There are several implications of the identification of these units. These far-travelled ashes: (1) highlight the need to consider "ultra" distal source volcanoes for unknown cryptotephra deposits,. (2) present an opportunity for physical volcanologists to examine why some eruptions have an exceptional distribution of ash that is not necessarily controlled by the magnitude of the event. (3) complicate the idea of using tephrostratigraphic frameworks to understand the frequency of eruptions towards aiding hazard planning and prediction (e.g. Swindles et al., 2011). (4) show that there is a real potential to link tropical and mid to high-latitude paleoenvironmental records. Jensen et al. (in press) Transatlantic correlation of the Alaskan White River Ash. Geology. Pyne-O'Donnell et al. (2012). High-precision ultra-distal Holocene tephrochronology in North America. Quaternary Science Reviews, 52, 6-11. Swindles et al. (2011). A 7000 yr perspective on volcanic ash clouds affecting northern Europe. Geology, 39, 887-890.

Bursaphelenchus antoniae sp. n. (Nematoda: Parasitaphelenchidae) associated with Hylobius sp. from Pinus pinaster in Portugal

Bursaphelenchus antoniae sp. n. is described and illustrated. Dauer juveniles were isolated from the body of the large pine weevil, Hylobius sp., collected from maritime pine (Pinus pinaster) stumps, in Portugal. Bursaphelenchus antoniae sp. n. was reared and maintained in P. pinaster wood segments and on Petri dish cultures of the fungi Botrytis cinerea and Monilinia fructicola. The new species is characterised by a relatively small body length of ca 583 μm (females) and 578 μm (males), a lateral field with two incisures, presence of a small vulval flap and a conoid female tail with a rounded or pointed terminus. Males have stout spicules with a disc-like cucullus and seven caudal papillae arranged as a single midventral precloacal papilla, one precloacal pair and two postcloacal pairs. In the character of the lateral field, B. antoniae sp. n. comes close to B. abietinus, B. rainulfi and B. hylobianum, whilst spicule characters place it within the piniperdae-group sensu Ryss et al. Morphologically, B. antoniae sp. n. is closest to B. hylobianum; the spicules of these two species having flattened, wing-like, alae on the distal third of the lamina. Bursaphelenchus antoniae sp. n. is distinguished from B. hylobianum on the arrangement of the caudal papillae (two vs three pairs). ITS-RFLP profiles and the failure to hybridise support the separation of the two species. Phylogenetic analysis of the new species, based on the 18S rDNA sequence, supports the inclusion of this new species in the B. hylobianum-group sensu Braasch. Sequence analysis of the 28S rDNA D2/D3 domain did not place the new species in a definite group.

The importance of the pelagic larval phase of the wedge shell Donax trunculus (L.): implications for the management of the fishery

The wedge shell, Donax trunculus, inhabits high energy environment of exposed sandy beaches from the Atlantic coast of France to Senegal. Like all Donacidae, it is relative small, flat-shaped with elongated solid shells. It is a highly demanded and valuable species mainly in Algarve, with the dredge fleet increasing the pressure on species stocks. In 1986 the Portuguese Institute for the Ocean and Atmosphere (IPMA) initiated a bivalve survey program to evaluate the stock status of species with economical valuable but always on the adult population. Since then, several managing measures were implemented to guarantee bivalves’ sustainable exploitation. Despite the available information on the abundance and distribution of the wedge shell along the Algarve coast, no information on the larval planktonic phase is available. To fill in this gap, the present study aimed at obtaining, for the first time information on the broodstock condition and on the pelagic phase of the wedge shell in the Algarve coast.