2,416 research outputs found
Grain-size trend analysis for the determination of non-biogenic sediment transport pathways on the Kwinte Bank (southern North Sea), in relation to sand dredging
Grain-size trend analysis is applied to the determination of sediment transport pathways over the Kwinte Bank, southern North Sea; which had been subjected to intensive dredging, within the context of the environmental impact of dredging activities. On the basis of the results of grain-size trend analysis, focused mainly upon the transportation of the non-biogenic sedimentary material (<2 mm), it appears that: (i) there is a main sediment pathway over the western (bank crest) and central (dredged area) part of the bank directed toward the NE; whilst a secondary pathway is established over its eastern gently-sloping flank, having a SE direction. Further, the present analysis shows that the area of the central (dredged) depression acts more as a ‘by-passing’ zone rather than as a depo-centre for the nonbiogenic sediments. Comparison undertaken with the results of an earlier investigation, for a non-dredged area at the northern end of the same bank, reveals that the depression due to dredging modifies significantly the sediment transport pathways; this may be attributed to a change in the seabed morphology which, in turn, modifies the nearbed hydrodynamics (related to tide and/or storm events)
The value of preventing malaria in Tembien, Ethiopia
The authors measure the monetary value households place on preventing malaria in Tembien, Tigray Region, Ethiopia. They estimate a household demand function for a hypothetical malaria vaccine and compute the value of preventing malaria as the household's maximum willingness to pay to provide vaccines for all family members. They contrast willingness to pay with the traditional costs of illness (medical costs and time lost because of malaria). Their results indicate that the value of preventing malaria with vaccines is about US6 a bed net), only a third of the population of a 200-person village would sleep under bed nets.Early Child and Children's Health,Public Health Promotion,Disease Control&Prevention,Health Monitoring&Evaluation,Economic Theory&Research,Health Monitoring&Evaluation,Economic Theory&Research,Climate Change,Environmental Economics&Policies,Early Child and Children's Health
European marine aggregates resources: Origins, usage, prospecting and dredging techniques
Marine aggregates (sand and gravel) are important mineral resources and traded commodities. Their significance is bound to increase further, due to increasing coastal zone development, stricter environmental regulation concerning land-won aggregates and increasing demand for beach replenishment material. Marine aggregate (MA) deposits can be differentiated into relict and modern deposits. The former consist of sedimentary material deposited in the past and under different environmental and sedimentary regimes than those existing presently (e.g. the gravel/ sand deposits of the Pleistocene buried river valleys of the northwestern European shelves). The latter are deposits, which have been formed and controlled by the modern hydro-and sediment dynamic conditions (e.g. the linear sand banks of the southern North Sea). The present contribution reviews the current state of affairs in 9 representative European Member States concerning the prospecting and extraction (dredging) techniques as well as the levels of production and usage. The review has shown a mixed record as, in some of the studied States, marine aggregate production is an important and streamlined activity, whereas other States have not yet developed efficient marine aggregate policies and industries. It has also shown that although attempts have been lately made to coordinate the field, the industry still faces problems, which hinder its sustainable development. These include (amongst others): lack of standardisation of the relevant information, difficulties in the access to information, non-coherent regulatory regimes and limited collaboration/coordination between the marine scientific research establishments and the marine aggregate industry. These issues should be addressed as quickly as possible in order to exploit effectively this important mineral resource
Microfluidic SAXS study of lamellar and multilamellar vesicle phases of linear sodium alkylbenzenesulfonate surfactant with intrinsic isomeric distribution
The structure and flow behaviour of a concentrated aqueous solution (45 w.t. %) of the ubiquitous linear sodium alkylbenzene sulfonate (NaLAS) surfactant is investigated by microfluidic small-angle X-ray scatterong (SAXS) at 70 ⁰C. NaLAS is an intrinsically complex mixture of over 20 surfactant molecules, presenting coexisting micellar (L1) and lamellar (Lα) phases. Novel microfluidic devices were fabricated to ensure pressure and thermal resistance, ability to handle viscous fluids, and low SAXS background. Polarized light optical microscopy showed that the NaLAS solution exhibits wall slip in microchannels, with velocity profiles approaching plug flow. Microfluidic SAXS demonstrated the structural spatial heterogeneity of the system with a characteristic lengthscale of 50 nL. Using a statistical flow-SAXS analysis we identified the micellar phase and multiple coexisting lamellar phases with a continuous distribution of d spacings between 37.5 Å - 39.5 Å. Additionally, we showed that the orientation of NaLAS lamellar phases is strongly affected by a single microfluidic constriction. The bilayers align parallel to the velocity field upon entering a constriction and perpendicular to it upon exiting. On the other hand, multi-lamellar vesicle phases are not affected under the same flow conditions. Our results demonstrate that, despite the compositional complexity inherent to NaLAS, microfluidic SAXS can rigorously elucidate its structure and flow response
The HemQ coprohaem decarboxylase generates reactive oxygen species: implications for the evolution of classical haem biosynthesis
Bacteria require a haem biosynthetic pathway for the assembly of a variety of protein complexes including cytochromes, peroxidases, globins, and catalase. Haem is synthesised via a series of tetrapyrrole intermediates including non-metallated porphyrins such as protoporphyrin IX, which is well-known to generate reactive oxygen species (ROS) in the presence of light and oxygen. Staphylococcus aureus has an ancient haem biosynthetic pathway that proceeds via the formation of coproporphyrin III, a less reactive porphyrin. Herein, we demonstrate for the first time that HemY of S. aureus is able to generate both protoporphyrin IX and coproporphyrin III, and that the terminal enzyme of this pathway, HemQ, can stimulate the generation of protoporphyrin IX (but not coproporphyrin III). Assays with hydrogen peroxide, horseradish peroxidase, superoxide dismutase, and catalase confirm that this stimulatory effect is mediated by superoxide. Structural modelling reveals that HemQ enzymes do not possess the structural attributes that are common to peroxidases that form compound I [FeIV=O]+, which taken together with the superoxide data leaves Fenton chemistry as a likely route for the superoxide-mediated stimulation of protoporphyrinogen IX oxidase activity of HemY. This generation of toxic free radicals could explain why HemQ enzymes have not been identified in organisms that synthesise haem via the classical protoporphyrin IX pathway. This work has implications for the divergent evolution of haem biosynthesis in ancestral microorganisms and provides new structural and mechanistic insights into a recently discovered oxidative decarboxylase reaction
Practical mammography
‘Digital health’ is an overarching concept that currently lacks theoretical definition and common terminology. For instance, this broad and emerging field includes all of the following terms within its lexicon: mHealth, Wireless Health, Health 2.0, eHealth, e-Patient(s), Healthcare IT/Health IT, Big Data, Health Data, Cloud Computing, Quantified Self, Wearable Computing, Gamification, and Telehealth/Telemedicine [1]. However, whilst a definition is difficult to provide, in this overview it is considered that digital health is the use of digital media to transform the way healthcare provision is conceived and delivered. We consider it does this through three basic features
Alien Registration- Poulos, Paul A. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/32138/thumbnail.jp
Coca, Capitalism and Decolonization: State Violence in Bolivia through Coca Policy
I approach Bolivian coca policy under Evo Morales, Bolivia’s first indigenous President, as a site to examine the broader issue of decolonization. My paper argues that the new General Law of Coca, passed in March 2017, is part of a larger systemic pattern of violence towards historically disenfranchised communities in Bolivia, despite Morales’ indigenous Aymara identity and pro-coca activism. Drawing on interviews I conducted and a postcolonial theoretical framework, I analyze how although Morales has rhetorically advocated for indigenous communities and decolonizing Bolivia, colonial legacies supplanted in the subjectivity of Bolivians and institutions of its government have persisted. I suggest that it is not possible for any postcolonial state to decolonize if it embraces the forces of global capitalism — the same forces that drove the violence of colonialism. I use international relations theory and social movement theory to aid in the imagining of a path towards decolonization
Revisiting the Local Scaling Hypothesis in Stably Stratified Atmospheric Boundary Layer Turbulence: an Integration of Field and Laboratory Measurements with Large-eddy Simulations
The `local scaling' hypothesis, first introduced by Nieuwstadt two decades
ago, describes the turbulence structure of stable boundary layers in a very
succinct way and is an integral part of numerous local closure-based numerical
weather prediction models. However, the validity of this hypothesis under very
stable conditions is a subject of on-going debate. In this work, we attempt to
address this controversial issue by performing extensive analyses of turbulence
data from several field campaigns, wind-tunnel experiments and large-eddy
simulations. Wide range of stabilities, diverse field conditions and a
comprehensive set of turbulence statistics make this study distinct
Finding Our Fathers
We never considered how hard it was for our fathers to go to work every day, toiling away at a job they didn’t like. And even worse, seemingly having no other choices because their families were depending on them for their very existence. Growing up, our fathers did not have time for family; spending time with us was something remote from their daily life, making them a stranger in each of their perspective homes. Worse still, We were too young to understand why our fathers were not present. This essay reveals how we have attempted to make sense of the experience this distance between us and our fathers has caused in order to detoxify our individual images of our fathers. Detoxifying the image of father means recognizing that our fathers’ have been wounded as well.</p
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