5,159 research outputs found
Testing use of mitochondrial COI sequences for the identification and phylogenetic analysis of New Zealand caddisflies (Trichoptera)
We tested the hypothesis that cytochrome c oxidase subunit 1 (COI) sequences would successfully discriminate recognised species of New Zealand caddisflies. We further examined whether phylogenetic analyses, based on the COI locus, could recover currently recognised superfamilies and suborders. COI sequences were obtained from 105 individuals representing 61 species and all 16 families of Trichoptera known from New Zealand. No sequence sharing was observed between members of different species, and congeneric species showed from 2.3 to 19.5% divergence. Sequence divergence among members of a species was typically low (mean = 0.7%; range 0.0â8.5%), but two species showed intraspecific divergences in excess of 2%. Phylogenetic reconstructions based on COI were largely congruent with previous conclusions based on morphology, although the sequence data did not support placement of the purse-cased caddisflies (Hydroptilidae) within the uncased caddisflies, and, in particular, the Rhyacophiloidea. We conclude that sequence variation in the COI gene locus is an effective tool for the identification of New Zealand caddisfly species, and can provide preliminary phylogenetic inferences. Further research is needed to ascertain the significance of the few instances of high intra-specific divergence and to determine if any instances of sequence sharing will be detected with larger sample sizes
Injection of hydrogen and vacancy-type defects during dissolution of aluminum
Formation of interfacial nanoscale voids in Al during room-temperature caustic corrosion was characterized by positron annihilation spectroscopy (PAS) and compared with measurements of deuterium absorption using secondary ion mass spectrometry (SIMS). The hypothesis was investigated that voids are created from vacancy-hydrogen (Vac-H) defects introduced during corrosion. Evidence for both mobile and immobile forms of absorbed hydrogen was obtained, the latter present within distances of 50 nm from the metal-oxide interface, where voids were also found. During corrosion, the immobile hydrogen was found only during discrete 1-2 min intervals of time separated by periods of 1-2 min when it was not present. Model calculations suggested that this transient behavior is consistent with repeated nucleation and dissolution of clusters of Vac-H defects. Only some aspects of the time-dependence of the void concentration from PAS corresponded with that of absorbed hydrogen; the former is believed to be influenced by metallic impurities
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Bilingualism Is Associated with a Delayed Onset of Dementia but Not with a Lower Risk of Developing it: a Systematic Review with Meta-Analyses.
Some studies have linked bilingualism with a later onset of dementia, Alzheimer's disease (AD), and mild cognitive impairment (MCI). Not all studies have observed such relationships, however. Differences in study outcomes may be due to methodological limitations and the presence of confounding factors within studies such as immigration status and level of education. We conducted the first systematic review with meta-analysis combining cross-sectional studies to explore if bilingualism might delay symptom onset and diagnosis of dementia, AD, and MCI. Primary outcomes included the age of symptom onset, the age at diagnosis of MCI or dementia, and the risk of developing MCI or dementia. A secondary outcome included the degree of disease severity at dementia diagnosis. There was no difference in the age of MCI diagnosis between monolinguals and bilinguals [mean difference: 3.2; 95% confidence intervals (CI): -3.4, 9.7]. Bilinguals vs. monolinguals reported experiencing AD symptoms 4.7Â years (95% CI: 3.3, 6.1) later. Bilinguals vs. monolinguals were diagnosed with dementia 3.3Â years (95% CI: 1.7, 4.9) later. Here, 95% prediction intervals showed a large dispersion of effect sizes (-1.9 to 8.5). We investigated this dispersion with a subgroup meta-analysis comparing studies that had recruited participants with dementia to studies that had recruited participants with AD on the age of dementia and AD diagnosis between mono- and bilinguals. Results showed that bilinguals vs. monolinguals were 1.9Â years (95% CI: -0.9, 4.7) and 4.2 (95% CI: 2.0, 6.4) older than monolinguals at the time of dementia and AD diagnosis, respectively. The mean difference between the two subgroups was not significant. There was no significant risk reduction (odds ratio: 0.89; 95% CI: 0.68-1.16) in developing dementia among bilinguals vs. monolinguals. Also, there was no significant difference (Hedges' gâ=â0.05; 95% CI: -0.13, 0.24) in disease severity at dementia diagnosis between bilinguals and monolinguals, despite bilinguals being significantly older. The majority of studies had adjusted for level of education suggesting that education might not have played a role in the observed delay in dementia among bilinguals vs. monolinguals. Although findings indicated that bilingualism was on average related to a delayed onset of dementia, the magnitude of this relationship varied across different settings. This variation may be due to unexplained heterogeneity and different sources of bias in the included studies. Registration: PROSPERO CRD42015019100
On the relevance of large scale pulsed-laser deposition: Evidence of structural heterogeneities in ZnO thin films
Pulsed-laser deposition is known as a well-suited method for growing thin films of oxide compounds presenting a wide range of functional properties. A limitation of this method for industrial process is the very anisotropic expansion dynamics of the plasma plume, which induces difficulties to grow on large scale films with homogeneous thickness and composition. The specific aspect of the crystalline or orientation uniformity has not been investigated, despite its important role on oxide films properties. In this work, the crystalline parameters and the texture of zinc oxide films are studied as a function of position with respect to the central axis of the plasma plume. We demonstrate the existence of large non-uniformities in the films. The stoichiometry, the lattice parameter, and the distribution of crystallites orientations drastically depend on the position with respect to the plume axis, i.e., on the oblique incidence of the ablated species. The origin of these non-uniformities, in particular, the unexpected tilted orientation of the ZnO c-axis may be attributed to the combined effects of the oblique incidence and of the ratio between oxygen and zinc fluxes reaching the surface of the growing film
Australian Sphingidae â DNA Barcodes Challenge Current Species Boundaries and Distributions
© 2014 Rougerie et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article
High levels of intraspecific genetic divergences revealed for Antarctic springtails: evidence for small-scale isolation during Pleistocene glaciation
We examined levels of genetic variability within and among populations of three Antarctic springtail species (Arthropoda: Collembola) and tested the hypothesis that genetic divergences occur among glacially-isolated habitats. The study was conducted in southern Victoria Land, Ross Dependency, Antarctica, and samples were collected from locations in the vicinity of the Mackay Glacier. We analyzed mtDNA (cytochrome c oxidase subunit I; COI) sequence variability for 97 individuals representing three species (Gomphiocephalus hodgsoni, N = 67; Cryptopygus nivicolus, N = 20; and Antarcticinella monoculata, N = 8). Haplotype diversity and genetic divergences were calculated and used to indicate population variability and also to infer divergence times of isolated populations using molecular clock estimates. Two of the three species showed high levels of genetic divergence. Gomphiocephalus hodgsoni, a widespread and common species, showed 7.6% sequence divergence on opposite sides of the Mackay Glacier. The more range restricted C. nivicolus showed 4.0% divergence among populations. The third species, A. monoculata, was found in only one location. Molecular clock estimates based on sequence divergences suggest that populations separated within the last 4 Mya. We conclude that habitat fragmentation resulting from Pliocene (5 Mya) and Pleistocene (2 Mya to 10 Kya) glaciations has promoted and maintained high levels of diversity among isolated springtail populations on relatively small spatial scales. The region surrounding the Mackay Glacier is likely to have provided refugia for springtail populations during glacial maxima and remains an area of high genetic and species diversity for Collembola within the Ross Sea region
Association between inflammatory potential of diet and risk of depression in middle-aged women: the Australian longitudinal study on women's health
Dietary factors and inflammation markers have been shown to play a role in the development of depression. However, there are very few studies that have explored the association between inflammatory potential of diet and risk of depression. In this study, we examined the association between the dietary inflammatory index (DII), which was developed specifically to measure the inflammatory potential of diet, and risk of depression in the middle-aged cohort of the Australian Longitudinal Study on Women's Health. A total of 6438 women with a mean age of 52·0 (sd 1·4) years at baseline were followed-up at five surveys over 12 years (2001-2013). Depression was defined as a score of â„10 on the Center for Epidemiologic Studies Depression-10 scale. The DII score, a literature-derived, population-based dietary index that has been validated against several inflammatory markers, was computed on the basis of dietary intake assessed using a validated FFQ. Generalised estimating equations were used to estimate relative risk (RR) of depression according to DII score. Models were adjusted for energy intake, highest education completed, marital status, menopause status and symptoms, personal illness or injury, smoking status, physical activity, BMI and depression diagnosis or treatment. In total, 1156 women (18 %) had scoresâ„10 on the CESD scale over the course of 9 years. Women with the most anti-inflammatory diet had an approximately 20 % lower risk of developing depression compared with women with the most pro-inflammatory diet (RRDII quartile 1 v. 4: 0·81; 95 % CI 0·69, 0·96; P trend=0·03). These results suggest that an anti-inflammatory diet is associated with lower risk of depression in middle-aged Australian women
Selective substitution in orbital domains of a low doped manganite : an investigation from Griffiths phenomenon and modification of glassy features
An effort is made to study the contrast in magnetic behavior resulting from
minimal disorder introduced by substitution of 2.5% Ga or Al in Mn-site of
LaSrMnO. It is considered that Ga or Al selectively
creates disorder within the orbital domains or on its walls, causing
enhancement of Griffiths phase (GP) singularity for the former and
disappearance of it in the later case. It is shown that Ga replaces Mn
which is considered to be concentrated within the domains, whereas Al replaces
Mn which is segregated on the hole-rich walls, without causing any
significant effect on structure or ferromagnetic transition temperatures. Thus,
it is presumed that the effect of disorder created by Ga extend across the bulk
of the domain having correlation over similar length-scale resulting in
enhancement of GP phenomenon. On the contrary, effect of disorder created by Al
remains restricted to the walls resulting in the modification of the dynamics
arising from the domain walls and suppresses the GP. Moreover contrasting
features are observed in the low temperature region of the compounds; a
re-entrant spin glass like behavior is observed in the Ga doped sample, while
the observed characteristics for the Al doped sample is ascribed only to
modified domain wall dynamics with the absence of any glassy phase. Distinctive
features in third order susceptibility measurements reveals that the magnetic
ground state of the entire series comprises of orbital domain states. These
observations bring out the role of the nature of disorder on GP phenomenon and
also reconfirms the character of self-organization in low-doped manganites
Total Hydrocarbon Content (THC) Testing in Liquid Oxygen (LOX)
The measured Total Hydrocarbon Content (THC) levels in liquid oxygen (LOX) systems at Stennis Space Center (SSC) have shown wide variations. Examples of these variations include the following: 1) differences between vendor-supplied THC values and those obtained using standard SSC analysis procedures; and 2) increasing THC values over time at an active SSC test stand in both storage and run vessels. A detailed analysis of LOX sampling techniques, analytical instrumentation, and sampling procedures will be presented. Additional data obtained on LOX system operations and LOX delivery trailer THC values during the past 12-24 months will also be discussed. Field test results showing THC levels and the distribution of the THC's in the test stand run tank, modified for THC analysis via dip tubes, will be presented
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