4,036 research outputs found
A comprehensive, multi-process box-model approach to glacial-interglacial carbon cycling
The canonical question of which physical, chemical or biological mechanisms were responsible for oceanic uptake of atmospheric CO2 during the last glacial is yet unanswered. Insight from paleo proxies has led to a multitude of hypotheses but none so far have been convincingly supported in three dimensional numerical modelling experiments. The processes that influence the CO2 uptake and export production are inter-related and too complex to solve conceptually while complex numerical models are time consuming and expensive to run which severely limits the combinations of mechanisms that can be explored. Instead, an intermediate inverse box model approach is used here in which the whole parameter space is explored. The glacial circulation and biological production states are derived from these using proxies of glacial export production and the need to draw down CO2 into the ocean. We find that circulation patterns which explain glacial observations include reduced Antarctic Bottom Water formation and high latitude mixing and to a lesser extent reduced equatorial upwelling. The proposed mechanism of CO2 uptake by an increase of eddies in the Southern Ocean, leading to a reduced residual circulation, is not supported. Regarding biological mechanisms, an increase in the nutrient utilization in either the equatorial regions or the northern polar latitudes can reduce atmospheric CO2 and satisfy proxies of glacial export production. Consistent with previous studies, CO2 is drawn down more easily through increased productivity in the Antarctic region than the sub-Antarctic, but that violates observations of lower export production there
Bullying and Victimization among Children Raised by Grandparents
Increasing numbers of school-age children are being raised by their grandparents. Yet, a dearth of research investigates the children in these families. The few studies suggest the children experience higher levels of academic, behavioral, and emotional difficulties than their peers. These behaviors are often associated with involvement in bullying, but no empirical research investigates bullying among children raised by their grandparents. This current study helps to fill the noted lack of research in this area and the gap in the literature by investigating the intersection of these two important phenomena â bullying and children raised by their grandparents. This study uses a nationally representative U.S. sample of 3,347 participants from the large-scale 2009-2010 âHealth Behavior in School-aged Childrenâ survey. The results indicate children raised by their grandparents bully more frequently, but are not victims of bullying more frequently than children living in other head of household family care arrangements. The children and their grandparents as well as their teachers will likely benefit from specific prevention and intervention strategies to ameliorate risk of bullying behavior
Smart Cities and M<sup>3</sup>: Rapid Research, Meaningful Metrics and Co-Design
The research described in this paper is undertaken under the banner of the smart city, a concept that captures the way urban spaces are re-made by the incursion of new technology. Much of smart is centred on converting everyday activities into data, and using this data to generate knowledge mediated by technology. Ordinary citizens, those that may have their lives impacted by the technology, usually are not properly involved in the âsmartificationâ process. Their perceptions, concerns and expectations should inform the conception and development of smart technologies at the same extent. How to engage general public with smart cities research is the central challenge for the Making Metrics Meaningful (MMM) project. Applying a rapid participatory method, âImagineâ over a five-month period (March â July) the research sought to gain insights from the general public into novel forms of information system innovation. This brief paper describes the nature of the accelerated research undertaken and explores some of the themes which emerged in the analysis. Generic themes, beyond the remit of an explicit transport focus, are developed and pointers towards further research directions are discussed. Participatory methods, including engaging with self- selected transport users actively through both picture creation and programmatically specific musical âsignaturesâ as well as group discussion, were found to be effective in eliciting usersâ own concerns, needs and ideas for novel information systems
Acquired neuromyotonia following upper respiratory tract infection: a case report
We present a 37-year-old male subject who presented with burning sensations in his hands and feet with generalised twitching of his limbs, trunk and face. His symptoms developed 2 weeks after an upper respiratory tract infection. There was associated facial flushing and disturbed night sleep but no memory impairment or generalised sweating. Examination showed generalised myokymia and fasciculations and electromyography revealed widespread continuous semi-rhythmic doublets and triplets of low frequency with interspersed silent periods. Anti voltage gated potassium channel antibodies, antinuclear antibodies, anti-acetylcholine receptor antibodies and the anti-neuronal antibodies anti Hu, anti Yo and anti Ri were all negative. His symptoms improved slightly on lamotrigine and amitriptyline
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Controls on the spatial distribution of oceanic <i>δ</i><sup>13</sup>C<sub>DIC</sub>
We describe the design and evaluation of a large ensemble of coupled climateâcarbon cycle simulations with the Earth system model of intermediate complexity GENIE. This ensemble has been designed for application to a range of carbon cycle questions, including the causes of late- Quaternary fluctuations in atmospheric CO2. Here we evaluate the ensemble by applying it to a transient experiment over the recent industrial era (1858 to 2008 AD). We employ singular vector decomposition and principal component emulation to investigate the spatial modes of ensemble variability of oceanic dissolved inorganic carbon (DIC) δ13C, considering both the spun-up pre-industrial state and the transient change. These analyses allow us to separate the natural (preindustrial) and anthropogenic controls on the δ13CDIC distribution. We apply the same dimensionally reduced emulation techniques to consider the drivers of the spatial uncertainty in anthropogenic DIC. We show that the sources of uncertainty related to the uptake of anthropogenic δ13CDIC and DIC are quite distinct. Uncertainty in anthropogenic δ13C uptake is controlled by airâsea gas exchange, which explains 63% of modelled variance. This mode of variability is largely absent from the ensemble variability in CO2 uptake, which is rather driven by uncertainties in thermocline ventilation rates. Although the need to account for airâsea gas exchange is well known, these results suggest that, to leading order, uncertainties in the ocean uptake of anthropogenic 13C and CO2 are governed by very different processes. This illustrates the difficulties in reconstructing one from the other, and furthermore highlights the need for careful targeting of both δ13CDIC and DIC observations to better constrain the ocean sink of anthropogenic CO2
Cathodoluminescence hyperspectral imaging of trench-like defects in InGaN/GaN quantum well structures
Optoelectronic devices based on the III-nitride system exhibit remarkably good optical efficiencies despite suffering from a large density of defects. In this work we use cathodoluminescence (CL) hyperspectral imaging to study InGaN/GaN multiple quantum well (MQW) structures. Different types of trench defects with varying trench width, namely wide or narrow trenches forming closed loops and open loops, are investigated in the same hyperspectral CL measurement. A strong redshift (90Â meV) and intensity increase of the MQW emission is demonstrated for regions enclosed by wide trenches, whereas those within narrower trenches only exhibit a small redshift (10Â meV) and a slight reduction of intensity compared with the defect-free surrounding area. Transmission electron microscopy (TEM) showed that some trench defects consist of a raised central area, which is caused by an increase of about 40% in the thickness of the InGaN wells. The causes of the changes in luminescences are also discussed in relation to TEM results identifying the underlying structure of the defect. Understanding these defects and their emission characteristics is important for further enhancement and development of light-emitting diodes
Stable Speckle Patterns for Nano-scale Strain Mapping up to 700 °C
The digital image correlation (DIC) of speckle patterns obtained by vapour-assisted gold remodelling at 200 â 350 °C has already been used to map plastic strains with submicron resolution. However, it has not so far proved possible to use such patterns for testing at high temperatures. Here we demonstrate how a gold speckle pattern can be made that is stable at 700 °C, to study deformation in a commercial TiAl alloy (Ti-45Al-2Nb- 2Mn(at%)-0.8 vol% TiB). The pattern is made up of a uniformly sized random array of Au islands as small as 15 nm in diameter, depending on reconstruction parameters, with a sufficiently small spacing to be suitable for nano-scale, nDIC, strain mapping at a subset size of 60 Ă 60 nm . It can be used at temperatures up to 700 °C for many hours, for high cycle fatigue testing for instance. There is good particle attachment to the substrate. It can withstand ultra-sound cleaning, is thermally stable and has a high atomic number contrast for topography-free backscatter electron imaging.EPSRC / Rolls-Royce Strategic Partnership (EP/M005607/1
Stress Hormones: A Link between Maternal Condition and SexâBiased Reproductive Investment
Abstract: In species where offspring fitness is sexâspecifically influenced by maternal reproductive condition, sex allocation theory predicts that poorâquality mothers should invest in the evolutionarily less expensive sex. Despite an accumulation of evidence that mothers can sexâspecifically modulate investment in offspring in relation to maternal quality, few mechanisms have been proposed as to how this is achieved. We explored a hormonal mechanism for sexâbiased maternal investment by measuring and experimentally manipulating baseline levels of the stress hormone corticosterone in laying wild female European starlings (Sturnus vulgaris) and examining effects on sex ratio and sexâspecific offspring phenotype adjustment. Here we show that baseline plasma corticosterone is negatively correlated with energetic body condition in laying starlings, and subsequent experimental elevation of maternal baseline plasma corticosterone increased yolk corticosterone without altering maternal condition or egg quality per se. Hormonal elevation resulted in the following: femaleâbiased hatching sex ratios (caused by elevated male embryonic mortality), lighter male offspring at hatching (which subsequently grew more slowly during postnatal development), and lower cellâmediated immune (phytohemagglutinin) responses in males compared with controlâborn males; female offspring were unaffected by the manipulation in both years of the study. Elevated maternal corticosterone therefore resulted in a sexâbiased adjustment of offspring quality favorable to female offspring via both a sex ratio bias and a modulation of male phenotype at hatching. In birds, deposition of yolk corticosterone may benefit mothers by acting as a betâhedging strategy in stochastic environments where the correlation between environmental cues at laying (and therefore potentially maternal condition) and conditions during chickârearing might be low and unpredictable. Together with recent studies in other vertebrate taxa, these results suggest that maternal stress hormones provide a mechanistic link between maternal quality and sexâbiased maternal investment in offspring
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