101 research outputs found
Determining the proximity effect-induced magnetic moment in graphene by polarized neutron reflectivity and x-ray magnetic circular dichroism
We report the magnitude of the induced magnetic moment in CVD-grown epitaxial and rotated-domain graphene in proximity with a ferromagnetic Ni film, using polarized neutron reflectivity (PNR) and X-ray magnetic circular dichroism (XMCD). The XMCD spectra at the C K-edge confirm the presence of a magnetic signal in the graphene layer, and the sum rules give a magnetic moment of up to ∼0.47 μB/C atom induced in the graphene layer. For a more precise estimation, we conducted PNR measurements. The PNR results indicate an induced magnetic moment of ∼0.41 μB/C atom at 10 K for epitaxial and rotated-domain graphene. Additional PNR measurements on graphene grown on a nonmagnetic Ni9Mo1 substrate, where no magnetic moment in graphene is measured, suggest that the origin of the induced magnetic moment is due to the opening of the graphene’s Dirac cone as a result of the strong C pz-Ni 3d hybridization
The Complete Genome Sequence of Fibrobacter succinogenes S85 Reveals a Cellulolytic and Metabolic Specialist
Fibrobacter succinogenes is an important member of the rumen
microbial community that converts plant biomass into nutrients usable by its
host. This bacterium, which is also one of only two cultivated species in its
phylum, is an efficient and prolific degrader of cellulose. Specifically, it has
a particularly high activity against crystalline cellulose that requires close
physical contact with this substrate. However, unlike other known cellulolytic
microbes, it does not degrade cellulose using a cellulosome or by producing high
extracellular titers of cellulase enzymes. To better understand the biology of
F. succinogenes, we sequenced the genome of the type strain
S85 to completion. A total of 3,085 open reading frames were predicted from its
3.84 Mbp genome. Analysis of sequences predicted to encode for
carbohydrate-degrading enzymes revealed an unusually high number of genes that
were classified into 49 different families of glycoside hydrolases, carbohydrate
binding modules (CBMs), carbohydrate esterases, and polysaccharide lyases. Of
the 31 identified cellulases, none contain CBMs in families 1, 2, and 3,
typically associated with crystalline cellulose degradation. Polysaccharide
hydrolysis and utilization assays showed that F. succinogenes
was able to hydrolyze a number of polysaccharides, but could only utilize the
hydrolytic products of cellulose. This suggests that F.
succinogenes uses its array of hemicellulose-degrading enzymes to
remove hemicelluloses to gain access to cellulose. This is reflected in its
genome, as F. succinogenes lacks many of the genes necessary to
transport and metabolize the hydrolytic products of non-cellulose
polysaccharides. The F. succinogenes genome reveals a bacterium
that specializes in cellulose as its sole energy source, and provides insight
into a novel strategy for cellulose degradation
Glucose-6-Phosphate Dehydrogenase Deficiency in an Endemic Area for Malaria in Manaus: A Cross-Sectional Survey in the Brazilian Amazon
BACKGROUND: There is a paucity of information regarding glucose-6-phosphate dehydrogenase (G6PD) deficiency in endemic areas for malaria in Latin America. METHODOLOGY/PRINCIPAL FINDINGS: This study determined the prevalence of the G6PD deficiency in 200 male non-consanguineous individuals residing in the Ismail Aziz Community, on the outskirts of Manaus (Brazilian Amazon). Six individuals (3%) were deficient using the qualitative Brewer's test. Gel electrophoresis showed that five of these patients were G6PD A(-). The deficiency was not associated with the ethnic origin (P = 0.571). In a multivariate logistic regression analysis, G6PD deficiency protected against three or more episodes of malaria (P = 0.049), independently of the age, and was associated with a history of jaundice (P = 0.020) and need of blood transfusion (P = 0.045) during previous treatment for malarial infection, independently of the age and the previous malarial exposure. CONCLUSIONS/SIGNIFICANCE: The frequency of G6PD deficiency was similar to other studies performed in Brazil and the finding of a predominant G6PD A(-) variant will help the clinical management of patients with drug-induced haemolysis. The history of jaundice and blood transfusion during previous malarial infection may trigger the screening of patients for G6PD deficiency. The apparent protection against multiple malarial infections in an area primarily endemic for Plasmodium vivax needs further investigation
Adherence to 24-Hour Movement Guidelines for the Early Years and associations with social-cognitive development among Australian preschool children
Background: The new Australian 24-Hour Movement Guidelines for the Early Years recommend that, for preschoolers, a healthy 24-h includes: i) ≥180 min of physical activity, including ≥60 min of energetic play, ii) ≤1 h of sedentary screen time, and iii) 10–13 h of good quality sleep. Using an Australian sample, this study reports the proportion of preschool children meeting these guidelines and investigates associations with social-cognitive development.
Methods: Data from 248 preschool children (mean age = 4.2 ± 0.6 years, 57% boys) participating in the PATH-ABC study were analyzed. Children completed direct assessments of physical activity (accelerometry) and social cognition (the Test of Emotional Comprehension (TEC) and Theory of Mind (ToM)). Parents reported on children’s screen time and sleep. Children were categorised as meeting/not meeting: i) individual guidelines, ii) combinations of two guidelines, or iii) all three guidelines. Associations were examined using linear regression adjusting for child age, sex, vocabulary, area level socio-economic status and childcare level clustering.
Results: High proportions of children met the physical activity (93.1%) and sleep (88.7%) guidelines, whereas fewer met the screen time guideline (17.3%). Overall, 14.9% of children met all three guidelines. Children meeting the sleep guideline performed better on TEC than those who did not (mean difference [MD] = 1.41; 95% confidence interval (CI) = 0.36, 2.47). Children meeting the sleep and physical activity or sleep and screen time guidelines also performed better on TEC (MD = 1.36; 95% CI = 0.31, 2.41) and ToM (MD = 0.25; 95% CI = −0.002, 0.50; p = 0.05), respectively, than those who did not. Meeting all three guidelines was associated with better ToM performance (MD = 0.28; 95% CI = −0.002, 0.48, p = 0.05), while meeting a larger number of guidelines was associated with better TEC (3 or 2 vs. 1/none, p < 0.02) and ToM performance (3 vs. 2, p = 0.03).
Conclusions: Strategies to promote adherence to the 24-Hour Movement Behaviour Guidelines for the Early Years among preschool children are warranted. Supporting preschool children to meet all guidelines or more guidelines, particularly the sleep and screen time guidelines, may be beneficial for their social-cognitive development
Acquisition of uropygial gland microbiome by hoopoe nestlings
Mutualistic symbioses between animals and bacteria depend on acquisition of appropriate symbionts while avoiding exploitation by non-beneficial microbes. The mode of acquisition of symbionts would determine, not only the probability of encountering but also evolutionary outcomes of mutualistic counterparts. The microbiome inhabiting the uropygial gland of the European hoopoe (Upupa epops) includes a variety of bacterial strains, some of them providing antimicrobial benefits. Here, the mode of acquisition and stability of this microbiome is analyzed by means of Automated rRNA Intergenic Spacer Analysis and two different experiments. The first experiment impeded mothers’ access to their glands, thus avoiding direct transmission of microorganisms from female to offspring secretions. The second experiment explored the stability of the microbiomes by inoculating glands with secretions from alien nests. The first experiment provoked a reduction in similarity of microbiomes of mother and nestlings. Interestingly, some bacterial strains were more often detected when females had not access to their glands, suggesting antagonistic effects among bacteria from different sources. The second experiment caused an increase in richness of the microbiome of receivers in terms of prevalence of Operational Taxonomic Units (OTUs) that reduced differences in microbiomes of donors and receivers. That occurred because OTUs that were present in donors but not in receivers incorporated to the microbiome of the latter, which provoked that cross-inoculated nestlings got similar final microbiomes that included the most prevalent OTUs. The results are therefore consistent with a central role of vertical transmission in bacterial acquisition by nestling hoopoes and support the idea that the typical composition of the hoopoe gland microbiome is reached by the incorporation of some bacteria during the nestling period. This scenario suggests the existence of a coevolved core microbiome composed by a mix of specialized vertically transmitted strains and facultative symbionts able to coexist with them. The implications of this mixed mode of transmission for the evolution of the mutualism are discussedMinisterio de Ciencia e Innovación (España)Junta de Andalucí
Early intervention in Alzheimer’s disease: a health economic study of the effects of diagnostic timing
Structural Characteristics and Stellar Composition of Low Surface Brightness Disk Galaxies
We present UBVI surface photometry of a sample of low surface brightness
(LSB) disk galaxies. LSB disk galaxies are fairly well described as exponential
disks with no preferred value for either scale length, central surface
brightness, or rotational velocity. Indeed, the distribution of scale lengths
is indistinguishable from that of high surface brightness spirals, indicating
that dynamically similar galaxies (e.g., those with comparable Rv^2) exist over
a large range in surface density.
These LSB galaxies are strikingly blue. The complete lack of correlation
between central surface brightness and color rules out any fading scenario.
Similarly, the oxygen abundances inferred from HII region spectra are
uncorrelated with color so the low metallicities are not the primary cause of
the blue colors. While these are difficult to interpret in the absence of
significant star formation, the most plausible scenario is a stellar population
with a young mean age stemming from late formation and subsequent slow
evolution.
These properties suggest that LSB disks formed from low initial overdensities
with correspondingly late collapse times.Comment: Astronomical Journal, in press 45 pages uuencoded postscript (368K)
including 9 multipart figures also available by anonymous ftp @
ftp.ast.cam.ac.uk /pub/ssm/phot.uu CAP-30-210442962983742937
G6PD deficiency in Latin America: systematic review on prevalence and variants
Plasmodium vivax radical cure requires the use of primaquine (PQ), a drug that induces haemolysis in glucose-6-phosphate dehydrogenase deficient (G6PDd) individuals, which further hampers malaria control efforts. The aim of this work was to study the G6PDd prevalence and variants in Latin America (LA) and the Caribbean region. A systematic search of the published literature was undertaken in August 2013. Bibliographies of manuscripts were also searched and additional references were identified. Low prevalence rates of G6PDd were documented in Argentina, Bolivia, Mexico, Peru and Uruguay, but studies from Curaçao, Ecuador, Jamaica, Saint Lucia, Suriname and Trinidad, as well as some surveys carried out in areas of Brazil, Colombia and Cuba, have shown a high prevalence (> 10%) of G6PDd. The G6PD A-202A mutation was the variant most broadly distributed across LA and was identified in 81.1% of the deficient individuals surveyed. G6PDd is a frequent phenomenon in LA, although certain Amerindian populations may not be affected, suggesting that PQ could be safely used in these specific populations. Population-wide use of PQ as part of malaria elimination strategies in LA cannot be supported unless a rapid, accurate and field-deployable G6PDd diagnostic test is made available
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