1,090 research outputs found
Trash on Arctic beach: Coastal pollution along Calypsostranda, Bellsund, Svalbard
Beach pollution is one of the most common hazards in present-day anthropogenic environments. Even in the remote Svalbard Archipelago, pollution impacts the beach system and can pose environmental threats. The significant increase in human activity observed in Svalbard over the last 20–30 years has resulted in a visible change in the amount of coastal pollution. A 5 km long transect of modern beach developed along Calypsostranda (Recherchefjorden, Bellsund) was surveyed in the summer of 2015 in order to characterize the beach pollution. During the survey 296 pieces of trash were found on beach surface. 82% of found trash was plastic, followed by glass (8%), and metal (5%). The comparison with previous pollution survey showed the significant increase of plastic waste in local beach environment. Similar problem has been recently recorded in other parts of Svalbard suggesting an urgent need for coastal pollution monitoring
Glacial landscape evolution in the Uummannaq region, West Greenland
The Uummannaq region is a mosaic of glacial landsystems, consistent with hypothesised landscape distribution resulting from variations in subglacial thermal regime. The region is dominated by selective linear erosion which has spatially and altitudinally partitioned the landscape. Low altitude areas are dominated by glacial scour, with higher elevations are dominated by plateaux or mountain valley and cirque glaciers. The appearance and nature of each landscape type varies locally with altitude and latitude, as a function of bedrock geology and average glacial conditions. Selective linear erosion has been a primary control on landscape distribution throughout Uummannaq, leading to plateau formation and the growth of a coalescent fjord system in the Uummannaq region. This has allowed the development of the Uummannaq ice stream’s (UIS) onset zone during glacial periods. Fjord development has been enhanced by a down-stream change in geology to less-resistant lithologies, increasing erosional efficiency and allowing a single glacial channel to develop, encouraging glacier convergence and the initiation of ice streaming. The landscape has been affected by several periods of regional uplift from 33 Ma to present, and has been subject to subsequent fluvial and glacial erosion. Uplift has removed surfaces from the impact of widespread warm-based glaciation, leaving them as relict landsurfaces. The result of this is a regional altitude-dependant continuum of glacial modification, with extreme differences in erosion between high and low elevation surfaces. This study indicates that processes of long-term uplift, glacial erosion/protection, and spatial variability in erosion intensity have produced a highly partitioned landscape
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Aviation turbulence: dynamics, forecasting, and response to climate change
Atmospheric turbulence is a major hazard in the aviation industry and can cause injuries to passengers and crew. Understanding the physical and dynamical generation mechanisms of turbulence aids with the development of new forecasting algorithms and, therefore, reduces the impact that it has on the aviation industry. The scope of this paper is to review the dynamics of aviation turbulence, its response to climate change, and current forecasting methods at the cruising altitude of aircraft. Aviation-affecting turbulence comes from three main sources: vertical wind shear instabilities, convection, and mountain waves. Understanding these features helps researchers to develop better turbulence diagnostics. Recent research suggests that turbulence will increase in frequency and strength with climate change, and therefore, turbulence forecasting may become more important in the future. The current methods of forecasting are unable to predict every turbulence event, and research is ongoing to find the best solution to this problem by combining turbulence predictors and using ensemble forecasts to increase skill. The skill of operational turbulence forecasts has increased steadily over recent decades, mirroring improvements in our understanding. However, more work is needed—ideally in collaboration with the aviation industry—to improve observations and increase forecast skill, to help maintain and enhance aviation safety standards in the future
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The mechanisms leading to a stratospheric hydration by overshooting convection
AbstractOvershoots are convective air parcels that rise beyond their level of neutral buoyancy. A giga-large-eddy simulation (100-m cubic resolution) of “Hector the Convector,” a deep convective system that regularly forms in northern Australia, is analyzed to identify overshoots and quantify the effect of hydration of the stratosphere. In the simulation, 1507 individual overshoots were identified, and 46 of them were tracked over more than 10 min. Hydration of the stratosphere occurs through a sequence of mechanisms: overshoot penetration into the stratosphere, followed by entrainment of stratospheric air and then by efficient turbulent mixing between the air in the overshoot and the entrained warmer air, leaving the subsequent mixed air at about the maximum overshooting altitude. The time scale of these mechanisms is about 1 min. Two categories of overshoots are distinguished: those that significantly hydrate the stratosphere and those that have little direct hydration effect. The former reach higher altitudes and hence entrain and mix with air that has higher potential temperatures. The resulting mixed air has higher temperatures and higher saturation mixing ratios. Therefore, a greater amount of the hydrometeors carried by the original overshoot sublimates to form a persistent vapor-enriched layer. This makes the maximum overshooting altitude the key prognostic for the parameterization of deep convection to represent the correct overshoot transport. One common convection parameterization is tested, and the results suggest that the overshoot downward acceleration due to negative buoyancy is too large relative to that predicted by the numerical simulations and needs to be reduced.This research was supported by the StratoClim project funded by the European Union Seventh Framework Programme under Grant Agree- ment 603557 and the Idex Teasao project. Todd Lane is supported by the Australian Research Council’s Centres of Excellence scheme (CE170100023). Computer re- sources were allocated by GENCI through Projects 90569 and 100231 (Grand Challenge Turing)
The composition and oxidative stability of vegetarian omega-3 algal oil nanoemulsions suitable for functional food enrichment
This is the peer reviewed version of the following article: Lane, K. E., Zhou, Q., Robinson, S., & Li, W. (2019). The composition and oxidative stability of vegetarian omega‐3 algal oil nanoemulsions suitable for functional food enrichment. Journal of the Science of Food and Agriculture, which has been published in final form at https://doi.org/10.1002/jsfa.10069. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.Abstract
Background: Long chain omega-3 polyunsaturated fatty acid (LCn3PUFA) nanoemulsion enriched foods offer potential to address habitually low oily fish intakes. Nanoemulsions increase LCn3PUFA bioavailability, but may cause lipid oxidation. This study examined oxidative stability of LCn3PUFA algal oil-in-water nanoemulsions created by ultrasound using natural and synthetic emulsifiers during 5-weeks of storage at 4, 20 and 40°C. Fatty acid composition, droplet size ranges and volatile compounds were analysed.
Results: No significant differences were found for fatty acid composition at various temperatures and storage times. Lecithin nanoemulsions had significantly larger droplet size ranges at baseline and during storage regardless of temperatures. While combined Tween 40 and lecithin nanoemulsions had low initial droplet size ranges, there were significant increases at 40°C after 5-weeks storage. Gas chromatograms identified hexanal and propanal as predominant volatile compounds, along with 2-ethylfuran; propan-3-ol; valeraldehyde. The Tween 40 only nanoemulsion sample showed formation of lower concentrations of volatiles compared to lecithin samples. Formation of hexanal and propanal remained stable at lower temperatures although higher concentrations were found in nanoemulsions than bulk oil. The lecithin only sample had formation of higher concentrations of volatiles at increased temperatures despite having significantly larger droplet size ranges than the other samples.
Conclusions: Propanal and hexanal were the most prevalent of five volatile compounds detected in bulk oil and lecithin and/or Tween 40 nanoemulsions. Oxidation compounds remained more stable at lower temperatures indicating suitability for enrichment of refrigerated foods. Further research to evaluate the oxidation stability of these systems 35 within food matrices is warranted
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
Assessment of rotatory laxity in anterior cruciate ligament-deficient knees using magnetic resonance imaging with Porto-knee testing device
Purpose Objective evaluation of both antero-posterior
translation and rotatory laxity of the knee remains a target
to be accomplished. This is true for both preoperative
planning and postoperative assessment of different ACL
reconstruction emerging techniques. The ideal measurement tool should be simple, accurate and reproducible,
while enabling to assess both ‘‘anatomy’’ and ‘‘function’’
during the same examination. The purpose of this study is
to evaluate the clinical effectiveness of a new in-housedeveloped testing device, the so-called Porto-knee testing
device (PKTD). The PKTD is aimed to be used on the
evaluation of both antero-posterior and rotatory laxity of
the knee during MRI exams.
Methods Between 2008 and 2010, 33 patients with ACLdeficient knees were enrolled for the purpose of this study.
All patients were evaluated in the office and under
anesthesia with Lachman test, lateral pivot-shift test and
anterior drawer test. All cases were studied preoperatively
with KT-1000 and MRI with PKTD, and examinations
performed by independent observers blinded for clinical
evaluation. During MRI, we have used a PKTD that applies
antero-posterior translation and permits free tibial rotation
through a standardized pressure (46.7 kPa) in the proximal
posterior region of the leg. Measurements were taken for
both knees and comparing side-to-side. Five patients with
partial ruptures were excluded from the group of 33.
Results For the 28 remaining patients, 3 women and 25
men, with mean age of 33.4 ± 9.4 years, 13 left and 15 right
knees were tested. No significant correlation was noticed for
Lachman test and PKTD results (n.s.). Pivot-shift had a
strong positive correlation with the difference in anterior
translation registered in lateral and medial tibia plateaus of
injured knees (cor. coefficient = 0.80; p\0.05), and with
the difference in this parameter as compared to side-to-side
(cor. coefficient = 0.83; p\0.05).
Considering the KT-1000 difference between injured and
healthy knees, a very strong positive correlation was found
for side-to-side difference in medial (cor. coeffi-
cient = 0.73; p\0.05) and lateral (cor. coefficient = 0.5;
p\0.05) tibial plateau displacement using PKTD.
Conclusion The PKTD proved to be a reliable tool in
assessment of antero-posterior translation (comparing with
KT-1000) and rotatory laxity (compared with lateral pivotshift under anesthesia) of the ACL-deficient knee during
MRI examinatio
What we talk about when we talk about "global mindset": managerial cognition in multinational corporations
Recent developments in the global economy and in multinational corporations have placed significant emphasis on the cognitive orientations of managers, giving rise to a number of concepts such as “global mindset” that are presumed to be associated with the effective management of multinational corporations (MNCs). This paper reviews the literature on global mindset and clarifies some of the conceptual confusion surrounding the construct. We identify common themes across writers, suggesting that the majority of studies fall into one of three research perspectives: cultural, strategic, and multidimensional. We also identify two constructs from the social sciences that underlie the perspectives found in the literature: cosmopolitanism and cognitive complexity and use these two constructs to develop an integrative theoretical framework of global mindset. We then provide a critical assessment of the field of global mindset and suggest directions for future theoretical and empirical research
Identifying key controls on storm formation over the Lake Victoria Basin
The Lake Victoria region in East Africa is a hotspot for intense convective storms that are responsible for the deaths of thousands of fisherman each year. The processes responsible for the initiation, development and propagation of the storms are poorly understood and forecast skill is limited. Key processes for the lifecycle of two storms are investigated using Met Office Unified Model convection-permitting simulations with 1.5 km horizontal gridspacing. The two cases are analysed alongside a simulation of a period with no storms to assess the roles of the lake–land breeze, downslope mountain winds, prevailing large-scale winds and moisture availability. Whilst seasonal changes in large-scale moisture availability play a key role in storm development, the lake–land breeze circulation is a major control on the initiation location, timing and propagation of convection. In the dry season, opposing offshore winds form a bulge of moist air above the lake surface overnight that extends from the surface to ~1.5 km and may trigger storms in high CAPE/low CIN environments. Such a feature has not been explicitly observed or modelled in previous literature. Storms over land on the preceding day are shown to alter the local atmospheric moisture and circulation to promote storm formation over the lake. The variety of initiation processes and differing characteristics of just two storms analysed here show that the mean diurnal cycle over Lake Victoria alone is inadequate to fully understand storm formation. Knowledge of daily changes in local-scale moisture variability and circulations are key for skilful forecasts over the lake
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