Size-resolved aerosol fluxes above a temperate broadleaf forest

Aerosol fluxes were measured by eddy-correlation for 8 weeks of the summer and fall of 2011 above a temperate broadleaf forest in central Ontario, Canada. These size-resolved measurements apply to particles with optical diameters between 50 and 500 nm and are the first ones reported above a temperate deciduous forest. The particle spectrometer was located on top of the flux tower in order to reduce signal dampening in the tube and thus maximize measurement efficiency. The 8-week data set extends into autumn, capturing leaf senescence and loss, offering a rare opportunity to investigate the influence of leaf area index on particle transfer. A distinct pattern of emission and deposition that depends on the particle size is highlighted: while the smallest particles (dp  100 nm) are preferentially deposited (62% of the time). For the size bins with detection efficiency above 50% (68–292 nm), the median transfer velocity for each bin varies between +1.34 and −2.69 mm s−1 and is equal to −0.21 mm s−1 for the total particle count. The occurrence of the upward fluxes shows a marked diurnal pattern. Possible explanations for these upward fluxes are proposed. The measurements, and their comparison with an existing model, highlight some of the key drivers of the particle transfer onto a broadleaf forest: particle size, friction velocity, leaf area index and atmospheric stability.We are grateful to the Haliburton forest staff and owner for their support, as well as Ting Zheng and Jing Ming Chen (Dept of Geography, Univ. of Toronto) for sharing the TRAC instrument LAI data. The UHSAS and SMPS instruments were contributed by the Canadian Aerosol Research Network, funded by the Canada Foundation for Innovation. (Canada Foundation for Innovation)First author draf

Genetic variation among lambs in peripheral IgE activity against the larval stages of <i>Teladorsagia circumcincta</i>

IgA and IgE activity against Teladorsagia circumcincta was investigated in a flock of Texel lambs following natural, mixed nematode infection among lambs. The distribution of IgA activity was similar to a gamma distribution whereas IgE activity was different. Box-Cox analysis demonstrated that X0.25 was a suitable transformation to normalise IgE responses. The transformed IgE activity was under moderate to strong genetic control. Nine different allergens were identified by proteomic analysis. Tropomyosin was selected for further analysis. IgE activity against tropomyosin was moderately heritable and associated with decreased egg counts and with reduced body weight at the time of sampling

Are subjectively scored linear type traits suitable predictors of the genetic merit for feed intake in grazing Holstein-Friesian dairy cows?

peer-reviewedMeasuring dry matter intake (DMI) in grazing dairy cows using currently available techniques is invasive, time consuming, and expensive. An alternative to directly measuring DMI for use in genetic evaluations is to identify a set of readily available animal features that can be used in a multitrait genetic evaluation for DMI. The objectives of the present study were thus to estimate the genetic correlations between readily available body-related linear type traits and DMI in grazing lactating Holstein-Friesian cows, but importantly also estimate the partial genetic correlations between these linear traits and DMI, after adjusting for differences in genetic merit for body weight. Also of interest was whether the predictive ability derived from the estimated genetic correlations materialized upon validation. After edits, a total of 8,055 test-day records of DMI, body weight, and milk yield from 1,331 Holstein-Friesian cows were available, as were chest width, body depth, and stature from 47,141 first lactation Holstein-Friesian cows. In addition to considering the routinely recorded linear type traits individually, novel composite traits were defined as the product of the linear type traits as an approximation of rumen volume. All linear type traits were moderately heritable, with heritability estimates ranging from 0.27 (standard error = 0.14) to 0.49 (standard error = 0.15); furthermore, all linear type traits were genetically correlated (0.29 to 0.63, standard error 0.14 to 0.12) with DMI. The genetic correlations between the individual linear type traits and DMI, when adjusted for genetic differences in body weight, varied from −0.51 (stature) to 0.48 (chest width). These genetic correlations between DMI and linear type traits suggest linear type traits may be useful predictors of DMI, even when body weight information is available. Nonetheless, estimated genetic merit of DMI derived from a multitrait genetic evaluation of linear type traits did not correlate strongly with actual DMI in a set of validation animals; the benefit was even less if body weight data were also available

Mott Transition in Degenerate Hubbard Models: Application to Doped Fullerenes

The Mott-Hubbard transition is studied for a Hubbard model with orbital degeneracy N, using a diffusion Monte-Carlo method. Based on general arguments, we conjecture that the Mott-Hubbard transition takes place for U/W \propto \sqrt{N}, where U is the Coulomb interaction and W is the band width. This is supported by exact diagonalization and Monte-Carlo calculations. Realistic parameters for the doped fullerenes lead to the conclusion that stoichiometric A_3 C_60 (A=K, Rb) are near the Mott-Hubbard transition, in a correlated metallic state.Comment: 4 pages, revtex, 1 eps figure included, to be published in Phys.Rev.B Rapid Com

Cortical Structure and Cognition in Infants and Toddlers

Cortical structure has been consistently related to cognitive abilities in children and adults, yet we know little about how the cortex develops to support emergent cognition in infancy and toddlerhood when cortical thickness (CT) and surface area (SA) are maturing rapidly. In this report, we assessed how regional and global measures of CT and SA in a sample (N = 487) of healthy neonates, 1-year-olds, and 2-year-olds related to motor, language, visual reception, and general cognitive ability. We report novel findings that thicker cortices at ages 1 and 2 and larger SA at birth, age 1, and age 2 confer a cognitive advantage in infancy and toddlerhood. While several expected brain-cognition relationships were observed, overlapping cortical regions were also implicated across cognitive domains, suggesting that infancy marks a period of plasticity and refinement in cortical structure to support burgeoning motor, language, and cognitive abilities. CT may be a particularly important morphological indicator of ability, but its impact on cognition is relatively weak when compared with gestational age and maternal education. Findings suggest that prenatal and early postnatal cortical developments are important for cognition in infants and toddlers but should be considered in relation to other child and demographic factors

Long‐Chain Polyunsaturated Fatty Acids and Lipid Peroxidation Products in Donor Human Milk in the United Kingdom: Results From the LIMIT 2‐Centre Cross‐Sectional Study

Background: Donor human milk is increasingly used as alternative to mother’s own milk to feed preterm infants, however, it may provide less long-chain polyunsaturated fatty acid (LCPUFA), and more oxidised lipids, which may be detrimental for preterm infant health and development. Levels have not been reported for donor human milk in the U.K. Methods: Donor human milk (n=19) from two neonatal units, milk from preterm mothers from a neonatal unit (n=10), and term mothers from the community (n=11) were analysed for fatty acid, malondialdehyde, 4-hydroxy-2-nonenal, and hexanal content. Study registration: NCT03573531 Results: Donor human milk had significantly lower absolute LCPUFA content compared to term milk (P<0.001) and significantly lower omega-3 PUFAs than preterm milk (P<0.05), although relative LCPUFA composition did not differ. Exclusive donor human milk feeding leads to significantly lower fat (3.7 vs. 6.7 g/d) and LCPUFA (DHA: 10.6 vs. 16.8 mg/d; ARA: 17.4 vs. 25.2 mg/d) intake than recommended by ESPGHAN, and provides only 17.3% and 43.1% of the in utero accreted ARA and DHA. Donor human milk also had the highest proportion of lipid peroxidation. Conclusions: This study confirms that donor human milk in the U.K. has insufficient levels of LCPUFAs for preterm infants. It demonstrates for the first time that donor human milk has the highest level of lipid peroxidation, compared to preterm or term milk. This has important implications for preterm infant nutrition, as exclusive donor human milk feeding might not be suitable long-term, and may contribute to the development of major preterm neonatal morbidities

Dysfunctional Dopaminergic Neurones in Mouse Models of Huntington's Disease: A Role for SK3 Channels

Background: Huntington's disease (HD) is a late-onset fatal neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the gene coding for the protein huntingtin and is characterised by progressive motor, psychiatric and cognitive decline. We previously demonstrated that normal synaptic function in HD could be restored by application of dopamine receptor agonists, suggesting that changes in the release or bioavailability of dopamine may be a contributing factor to the disease process. Objective: In the present study, we examined the properties of midbrain dopaminergic neurones and dopamine release in presymptomatic and symptomatic transgenic HD mice. Methods and Results:Using intracellular sharp recordings and immunohistochemistry, we found that neuronal excitability was increased due to a loss of slow afterhyperpolarisation and that these changes were related to an apparent functional loss and abnormal distribution of SK3 channels (KCa2.3 encoded by the KCNN3 gene), a class of small-conductance calcium-activated potassium channels. Electrochemical detection of dopamine showed that this observation was associated with an enhanced dopamine release in presymptomatic transgenic mice and a drastic reduction in symptomatic animals. These changes occurred in the context of a progressive expansion in the CAG repeat number and nuclear localisation of mutant protein within the substantia nigra pars compacta. Conclusions: Dopaminergic neuronal dysfunction is a key early event in HD disease progression. The initial increase in dopamine release appears to be related to a loss of SK3 channel function, a protein containing a polyglutamine tract. Implications for polyglutamine-mediated sequestration of SK3 channels, dopamine-associated DNA damage and CAG expansion are discussed in the context of HD.</br

Electromagnetic characteristics of bilayer quantum Hall systems in the presence of interlayer coherence and tunneling

The electromagnetic characteristics of bilayer quantum Hall systems in the presence of interlayer coherence and tunneling are studied by means of a pseudospin-texture effective theory and an algebraic framework of the single-mode approximation, with emphasis on clarifying the nature of the low-lying neutral collective mode responsible for interlayer tunneling phenomena. A long-wavelength effective theory, consisting of the collective mode as well as the cyclotron modes, is constructed. It is seen explicitly from the electromagnetic response that gauge invariance is kept exact, this implying, in particular, the absence of the Meissner effect in bilayer systems. Special emphasis is placed on exploring the advantage of looking into quantum Hall systems through their response; in particular, subtleties inherent to the standard Chern-Simons theories are critically examined.Comment: 9 pages, Revtex, to appear in Phys. Rev.

Genetic influences on neonatal cortical thickness and surface area

Genetic and environmental influences on cortical thickness (CT) and surface area (SA) are thought to vary in a complex and dynamic way across the lifespan. It has been established that CT and SA are genetically distinct in older children, adolescents, and adults, and that heritability varies across cortical regions. Very little, however, is known about how genetic and environmental factors influence infant CT and SA. Using structural MRI, we performed the first assessment of genetic and environmental influences on normal variation of SA and CT in 360 twin neonates. We observed strong and significant additive genetic influences on total SA (a2 = 0.78) and small and nonsignificant genetic influences on average CT (a2 = 0.29). Moreover, we found significant genetic overlap (genetic correlation = 0.65) between these global cortical measures. Regionally, there were minimal genetic influences across the cortex for both CT and SA measures and no distinct patterns of genetic regionalization. Overall, outcomes from this study suggest a dynamic relationship between CT and SA during the neonatal period and provide novel insights into how genetic influences shape cortical structure during early development

Hydrogen accommodation in Zr second phase particles: Implications for H pick-up and hydriding of Zircaloy-2 and Zircaloy-4

Ab-initio computer simulations have been used to predict the energies associated with the accommodation of H atoms at interstitial sites in {\alpha}, {\beta}-Zr and Zr.M intermetallics formed with common alloying additions (M = Cr, Fe, Ni). Intermetallics that relate to the Zr2(Ni,Fe) second phase particles (SPPs) found in Zircaloy-2 exhibit favourable solution enthalpies for H. The intermetallic phases that relate to the Zr(Cr,Fe)2 SPPs, found predominantly in Zircaloy-4, do not offer favourable sites for interstitial H. It is proposed that Zr(Cr,Fe)2 particles may act as bridges for the migration of H through the oxide layer, whilst the Zr2(Ni,Fe)-type particles will trap the migrating H until these are dissolved or fully oxidised