387 research outputs found
Near-surface profiles of aerosol number concentration and temperature over the Arctic Ocean
Temperature and particle number concentration profiles were measured at small height intervals above open and frozen leads and snow surfaces in the central Arctic. The device used was a gradient pole designed to investigate potential particle sources over the central Arctic Ocean. The collected data were fitted according to basic logarithmic flux-profile relationships to calculate the sensible heat flux and particle deposition velocity. Independent measurements by the eddy covariance technique were conducted at the same location. General agreement was observed between the two methods when logarithmic profiles could be fitted to the gradient pole data. In general, snow surfaces behaved as weak particle sinks with a maximum deposition velocity <i>v</i><sub>d</sub> = 1.3 mm s<sup>&minus;1</sup> measured with the gradient pole. The lead surface behaved as a weak particle source before freeze-up with an upward flux <i>F</i><sub>c</sub> = 5.7 &times; 10<sup>4</sup> particles m<sup>&minus;2</sup> s<sup>&minus;1</sup>, and as a relatively strong heat source after freeze-up, with an upward maximum sensible heat flux <i>H</i> = 13.1 W m<sup>&minus;2</sup>. Over the frozen lead, however, we were unable to resolve any significant aerosol profiles
Near-surface profiles of aerosol number concentration and temperature over the Arctic Ocean
Temperature and particle number concentration profiles were measured at small height intervals above open and frozen leads and snow surfaces in the central Arctic. The device used was a gradient pole designed to investigate potential particle sources over the central Arctic Ocean. The collected data were fitted according to basic logarithmic flux-profile relationships to calculate the sensible heat flux and particle deposition velocity. Independent measurements by the eddy covariance technique were conducted at the same location. General agreement was observed between the two methods when logarithmic profiles could be fitted to the gradient pole data. In general, snow surfaces behaved as weak particle sinks with a maximum deposition velocity vd = 1.3 mm sâ1 measured with the gradient pole. The lead surface behaved as a weak particle source before freeze-up with an upward flux Fc = 5.7 Ă 104 particles mâ2 sâ1, and as a relatively strong heat source after freeze-up, with an upward maximum sensible heat flux H = 13.1 W mâ2. Over the frozen lead, however, we were unable to resolve any significant aerosol profiles
Florivory Shapes both Leaf and Floral Interactions
Florivory, or the consumption of flowers, is a ubiquitous interaction that can reduce plant reproduction directly by damaging reproductive tissues and indirectly by deterring pollinators. However, we know surprisingly little about how florivory alters plant traits or the larger community of species interactions. Although leaf damage is known to affect floral traits and interactions in many systems, the consequences of floral damage for leaf traits and interactions are unknown. We manipulated floral damage in Impatiens capensisand measured effects on floral attractive traits and secondary chemicals, leaf secondary chemicals, floral interactions, leaf herbivory, and plant reproduction. We also examined relationships between early season floral traits and floral interactions, to explore which traits structure floral interactions. Moderate but not high florivory significantly increased relative selfed reproduction, leading to a shift in mating system away from outcrossing. Florivory increased leaf secondary compounds and decreased leaf herbivory, although mechanisms other than leaf chemistry may be responsible for some of the reduced leaf damage. Florivory altered four of seven measured interactions, including increased subsequent florivory and reduced flower spiders, although only leaf damage effects were significant after correcting for multiple tests. Pretreatment concentrations of floral anthocyanins and condensed tannins were associated with reduced levels of many floral antagonisms, including florivory, nectar larceny, and flower spider abundance, suggesting these traits play a role in floral resistance. Overall, our results indicate a broad range of community and potential evolutionary consequences of florivory through structuring subsequent floral interactions, altering leaf secondary chemicals, and shaping leaf herbivory
Parenting Stress Undermines Mother-Child Brain-to-Brain Synchrony: A Hyperscanning Study
Synchrony refers to the coordinated interplay of behavioural and physiological signals that reflect the bi-directional attunement of one partner to the other's psychophysiological, cognitive, emotional, and behavioral state. In mother-child relationships, a synchronous pattern of interaction indicates parental sensitivity. Parenting stress has been shown to undermine mother-child behavioural synchrony. However, it has yet to be discerned whether parenting stress affects brain-to-brain synchrony during everyday joint activities. Here, we show that greater parenting stress is associated with less brain-to-brain synchrony in the medial left cluster of the prefrontal cortex when mother and child engage in a typical dyadic task of watching animation videos together. This brain region overlaps with the inferior frontal gyrus, the frontal eye field, and the dorsolateral prefrontal cortex, which are implicated in inference of mental states and social cognition. Our result demonstrates the adverse effect of parenting stress on mother-child attunement that is evident at a brain-to-brain level. Mother-child brain-to-brain asynchrony may underlie the robust association between parenting stress and poor dyadic co-regulation. We anticipate our study to form the foundation for future investigations into mechanisms by which parenting stress impairs the mother-child relationship
Uncertain pasts and risk-sensitive futures in sub-Saharan urban transformation
This chapter explores the status and the scope for transition of risk- sensitive and transformative urban development in diverse cities of sub-Saharan Africa. Sub-Saharan Africa is important because of its large proportions of urban populations with high vulnerability and growing exposure to risks. High rates of urban growth pose increasing risks as we go into the future, yet there is also opportunity to reduce risk through integrating risk management into development. However, this opportunity space is often constrained by limited capacities to plan and manage the rapid urbanisation process, particularly in informal settlements. Limited capacities to prevent processes of risk accumulation pose threats to poverty reduction and sustainable development. In this context, there is an increasingly urgent need for squarely recognising and addressing the underlying vulnerabilities of urban populations and their root causes. Transitioning towards such sustainable urban pathways will require the strengthening of capacities and accountability of city authorities and broader governance systems, both formal and informal
Revising the hygroscopicity of inorganic sea salt particles
This is the final version of the article. Available from Springer Nature via the DOI in this record.Sea spray is one of the largest natural aerosol sources and plays an important role in the Earth's radiative budget. These particles are inherently hygroscopic, that is, they take-up moisture from the air, which affects the extent to which they interact with solar radiation. We demonstrate that the hygroscopic growth of inorganic sea salt is 8-15% lower than pure sodium chloride, most likely due to the presence of hydrates. We observe an increase in hygroscopic growth with decreasing particle size (for particle diameters <150ânm) that is independent of the particle generation method. We vary the hygroscopic growth of the inorganic sea salt within a general circulation model and show that a reduced hygroscopicity leads to a reduction in aerosol-radiation interactions, manifested by a latitudinal-dependent reduction of the aerosol optical depth by up to 15%, while cloud-related parameters are unaffected. We propose that a value of Îșs=1.1 (at RH=90%) is used to represent the hygroscopicity of inorganic sea salt particles in numerical models.P.Z. was partially financed by an Advanced Postdoc.Mobility fellowship of the Swiss National Science Foundation (grant no. P300P2_147776). M.E.S., C.L. and I.R. were financed by the Nordic Center of Excellence on Cryosphere-Atmosphere-Cloud-Climate-Interactions (NCoE CRAICC) and the Swedish Research Council (Vetenskapsradet). O.V. and A.V. were supported by the Academy of Finland Centre of Excellence (grant no. 272041) and The Doctoral School of the University of Eastern Finland. J.C.C. and M.G. received financial support from the European Research Commission via the ERC grant ERC-CoG 615922-BLACARAT. A.N. acknowledges support from a Georgia Power Scholar chair and a Cullen-Peck faculty fellowship. S.B. and M.M.-F. acknowledge funding by the Swiss National Science Foundation (grant no. 200020_146760/1). I. Tegen (TROPOS, Germany) is acknowledged for providing help with the sea spray source functions. We thank D. Eklöf and Z. Bacsik from the Department of Materials and Environmental Chemistry at Stockholm University for their assistance in the pycnometre and Fourier transform infrared spectrometer measurements. The ECHAM-HAMMOZ model is developed by a consortium composed of ETH Zurich, Max Planck Institut fĂŒr Meteorologie, Forschungszentrum JĂŒlich, University of Oxford, the Finnish Meteorological Institute and the Leibniz Institute for Tropospheric Research, and managed by the Center for Climate Systems Modeling (C2SM) at ETH Zurich
Variation in plasma oxidative status and testosterone level in relation to egg-eviction effort and age of brood-parasitic common cuckoo nestlings
To avoid competition for parental care, brood-parasitic Common Cuckoo (Cuculus canorus) nestlings evict all of the host's eggs and nestlings within a few days after hatching. Little is known about the physiological effects of eviction behavior on the cuckoo nestling's oxidative balance or about age-related variation in plasma oxidative status and testosterone level of developing birds. We examined whether the cuckoo nestling's plasma oxidative status was related to prior effort in eviction and quantified variation in the level of reactive oxygen metabolites, of nonenzymatic antioxidant capacity, and of testosterone concentration in plasma at various phases of the cuckoo's development. Levels of both reactive oxygen metabolites and antioxidant capacity were greater in older than in younger nestlings, suggesting that younger nestlings effectively counterbalance their increased production of free radicals, whereas, near fledging, levels of reactive oxygen metabolites increase despite improved antioxidant capacity. Possibly, overall energy expenditure increases with age and elevates the production of reactive oxygen species to a rate higher than what the antioxidant system could eliminate. Plasma testosterone level was the highest at nestlings' intermediate phase of growth. High levels of testosterone may be required during the period of fastest growth, and when the growth rate levels off near fledging, testosterone levels may also decline. Cuckoo chicks that evicted more host eggs from steeper nests had higher plasma levels of reactive oxygen metabolites shortly after the eviction period, suggesting that eviction is costly in terms of an increased level of oxidative stress. Para evitar la competencia por el cuidado parental, los polluelos parĂĄsitos de nidada de Cuculus canorus desalojan todos los huevos y los polluelos del hospedador a los pocos dĂas despuĂ©s de la eclosiĂłn. Se sabe poco sobre los efectos fisiolĂłgicos del comportamiento de desalojo en el balance oxidativo de los polluelos de C. canorus o sobre la variaciĂłn en el estatus oxidativo del plasma y el nivel de testosterona relacionado con la edad de las aves en desarrollo. Examinamos si el estatus oxidativo del plasma de los polluelos de C. canorus se relacionaba con un esfuerzo previo de desalojo y cuantificamos la variaciĂłn en el nivel de metabolitos reactivos de oxĂgeno, la capacidad antioxidante no enzimĂĄtica y la concentraciĂłn de testosterona en el plasma en varias fases del desarrollo de C. canorus. Tanto los niveles de metabolitos reactivos de oxĂgeno como la capacidad antioxidante fueron superiores en los polluelos de mayor edad que en los mĂĄs jĂłvenes, lo que sugiere que los polluelos de menor edad contrarrestan eficazmente el aumento de la producciĂłn de radicales libres, mientras que, cuando se aprĂłximan al abandono del nido, los niveles de metabolitos reactivos de oxĂgeno aumentan a pesar de una mejora en la capacidad antioxidante. Posiblemente, el gasto total de energĂa se incrementa con la edad, elevĂĄndose la producciĂłn de formas reactivas de oxĂgeno a una tasa mayor de la que el sistema antioxidante puede eliminar. El nivel de testosterona en el plasma fue mĂĄximo en la fase intermedia del crecimiento de los polluelos. Pueden requerirse altos niveles de testosterona durante el perĂodo de mayor crecimiento y, cuando la tasa de crecimiento se estabiliza cerca del abandono del nido, los niveles de testosterona tambiĂ©n podriĂĄn disminuir. Los polluelos de C. canorus que desalojaron mĂĄs huevos del hospedador en nidos con una estructura mĂĄs empinada tuvieron niveles de plasma de metabolitos reactivos de oxĂgeno en plasma mĂĄs altos poco despuĂ©s del perĂodo de desalojo, sugiriendo que el desalojo es costoso en tĂ©rminos de un incremento en el nivel de estrĂ©s oxidativo
Opacities of Singly and Doubly Ionised Neodymium and Uranium for Kilonova Emission Modeling
Even though the electromagnetic counterpart AT2017gfo to the binary neutron
star merger GW170817 is powered by the radioactive decay of r-process nuclei,
only few tentative identifications of light r-process elements have been made
so far. One of the major limitations for the identification of heavy nuclei is
incomplete or missing atomic data. While substantial progress has been made on
lanthanide atomic data over the last few years, for actinides there has been
less emphasis, with the first complete set of opacity data only recently
published. We perform atomic structure calculations of neodymium as
well as the corresponding actinide uranium . Using two different codes
(FAC and HFR) for the calculation of the atomic data, we investigate the
accuracy of the calculated data (energy levels and electric dipole transitions)
and their effect on kilonova opacities. For the FAC calculations, we optimise
the local central potential and the number of included configurations and use a
dedicated calibration technique to improve the agreement between theoretical
and available experimental atomic energy levels (AELs). For ions with vast
amounts of experimental data available, the presented opacities agree quite
well with previous estimations. On the other hand, the optimisation and
calibration method cannot be used for ions with only few available AELs. For
these cases, where no experimental nor benchmarked calculations are available,
a large spread in the opacities estimated from the atomic data obtained with
the various atomic structure codes is observed.We find that the opacity of
uranium is almost double the neodymium opacity.Comment: 20 pages, 13 figures. Accepted by MNRA
Prospective Prediction of Body Mass Index Trajectories using Multi-task Gaussian Processes
Clinicians often investigate the body mass index (BMI) trajectories of
children to assess their growth with respect to their peers, as well as to
anticipate future growth and disease risk. While retrospective modelling of BMI
trajectories has been an active area of research, prospective prediction of
continuous BMI trajectories from historical growth data has not been well
investigated. Using weight and height measurements from birth to age 10 years
from a longitudinal mother-offspring cohort, we leveraged a multi-task Gaussian
processes model, called MagmaClust, to derive probabilistic predictions for BMI
trajectories over various forecasting periods. Experiments were conducted to
evaluate the accuracy, sensitivity to missing values, and number of clusters.
The results were compared with cubic B-spline regression and a parametric
Jenss-Bayley mixed effects model. A downstream tool computing individual
overweight probabilities was also proposed and evaluated. In all experiments,
MagmaClust outperformed conventional models in prediction accuracy while
correctly calibrating uncertainty regardless of the missing data amount (up to
90\% missing) or the forecasting period (from 2 to 8 years in the future).
Moreover, the overweight probabilities computed from MagmaClust's uncertainty
quantification exhibited high specificity ( to ) and accuracy
( to ) in predicting the 10-year overweight status even from age 2
years. MagmaClust provides a probabilistic non-parametric framework to
prospectively predict BMI trajectories, which is robust to missing values and
outperforms conventional BMI trajectory modelling approaches. It also clusters
individuals to identify typical BMI patterns (early peak, adiposity rebounds)
during childhood. Overall, we demonstrated its potential to anticipate BMI
evolution throughout childhood, allowing clinicians to implement prevention
strategies.Comment: 17 pages, 9 figures, 5 table
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