Alzheimer's disease research: a network science approach

A limit number of studies have applied bibliometric visualisation to explore the network structure of Alzheimer’s Disease (AD). This paper uses CiteSpace, Carrot and VOSviewer to analyse and visualise the intellectual structure of AD, characterizing, quantitatively and qualitatively, the global scientific outputs, and identifying their trends. The 9,753 articles obtained from the science citation index expanded database (SCI-E), from Web-of-Science, were analysed. The publication data is analysed computationally to identify publication patterns, a rate of growth of publications, types of authorship collaboration, the most productive authors, countries, institutions, journals, keywords, the citation and keyword patterns, the hotspots and the areas of research on the AD. The paper presents a detailed analytical mapping of AD research and charts the progress of discipline with various useful parameters. The authors expect to contribute to the theory, supplying researchers with new tools and enabling practitioners to improve their knowledge about the AD evolution and trends.info:eu-repo/semantics/acceptedVersio

SuzakuSuzaku X-ray study of the double radio relic galaxy cluster CIZA J2242.8+5301

Content: We present the results from $Suzaku$ observations of the merging cluster of galaxies CIZA J2242.8+5301 at $z$=0.192. Aims. To study the physics of gas heating and particle acceleration in cluster mergers, we investigated the X-ray emission from CIZA J2242.8+5301, which hosts two giant radio relics in the northern/southern part of the cluster. Methods. We analyzed data from three-pointed Suzaku observations of CIZA J2242.8+5301 to derive the temperature distribution in four different directions. Results: The Intra-Cluster Medium (ICM) temperature shows a remarkable drop from 8.5$_{-0.6}^{+0.8}$ keV to 2.7$_{-0.4}^{+0.7}$ keV across the northern radio relic. The temperature drop is consistent with a Mach number ${\cal M}_n=2.7^{+0.7}_{-0.4}$ and a shock velocity $v_{shock:n}=2300_{-400}^{+700}\rm\,km\,s^{-1}$. We also confirm the temperature drop across the southern radio relic. However, the ICM temperature beyond this relic is much higher than beyond the northern one, which gives a Mach number ${\cal M}_s=1.7^{+0.4}_{-0.3}$ and shock velocity $v_{shock:s}=2040_{-410}^{+550}\rm \,km\,s^{-1}$. These results agree with other systems showing a relationship between the radio relics and shock fronts which are induced by merging activity. We compare the X-ray derived Mach numbers with the radio derived Mach numbers from the radio spectral index under the assumption of diffusive shock acceleration in the linear test particle regime. For the northern radio relic, the Mach numbers derived from X-ray and radio observations agree with each other. Based on the shock velocities, we estimate that CIZA J2242.8+5301 is observed approximately 0.6 Gyr after core passage. The magnetic field pressure at the northern relic is estimated to be 9% of the thermal pressure.Comment: 12 pages, 10 figures, A&A accepte

Evidence for the evolutionary steps leading to mecA-mediated ß-lactam resistance in staphylococci

The epidemiologically most important mechanism of antibiotic resistance in Staphylococcus aureus is associated with mecA–an acquired gene encoding an extra penicillin-binding protein (PBP2a) with low affinity to virtually all β-lactams. The introduction of mecA into the S. aureus chromosome has led to the emergence of methicillin-resistant S. aureus (MRSA) pandemics, responsible for high rates of mortality worldwide. Nonetheless, little is known regarding the origin and evolution of mecA. Different mecA homologues have been identified in species belonging to the Staphylococcus sciuri group representing the most primitive staphylococci. In this study we aimed to identify evolutionary steps linking these mecA precursors to the β-lactam resistance gene mecA and the resistance phenotype. We sequenced genomes of 106 S. sciuri, S. vitulinus and S. fleurettii strains and determined their oxacillin susceptibility profiles. Single-nucleotide polymorphism (SNP) analysis of the core genome was performed to assess the genetic relatedness of the isolates. Phylogenetic analysis of the mecA gene homologues and promoters was achieved through nucleotide/amino acid sequence alignments and mutation rates were estimated using a Bayesian analysis. Furthermore, the predicted structure of mecA homologue-encoded PBPs of oxacillin-susceptible and -resistant strains were compared. We showed for the first time that oxacillin resistance in the S. sciuri group has emerged multiple times and by a variety of different mechanisms. Development of resistance occurred through several steps including structural diversification of the non-binding domain of native PBPs; changes in the promoters of mecA homologues; acquisition of SCCmec and adaptation of the bacterial genetic background. Moreover, our results suggest that it was exposure to β-lactams in human-created environments that has driven evolution of native PBPs towards a resistance determinant. The evolution of β-lactam resistance in staphylococci highlights the numerous resources available to bacteria to adapt to the selective pressure of antibiotics

Desenvolvimento e precocidade de produção de coqueiros híbridos, consorciados com Gliricidia sepium.

ODS 2

VHF radar observations of the dip equatorial E-region during sunset in the Brazilian sector

Using the RESCO 50 MHz backscatter radar (2.33° S, 44.2° W, DIP: –0.5), at São Luís, Brazil, we obtained Range Time Intensity (RTI) maps covering the equatorial electrojet heights during daytime and evening. These maps revealed a scattering region at an altitude of about 108 km during the sunset period. The type of 3-m irregularity region we present here has not been reported before in the literature, to our knowledge. It was mainly observed around the Southern Hemisphere summer-solstice period, under quiet magnetic activity condition. The occurrence of this echo region coincides in local time with the maximum intensity of an evening pre-reversal eastward electric field of the ionospheric <i>F</i>-region. A tentative explanation is proposed here in terms of the theory of the divergence of the equatorial electrojet (EEJ) current in the evening ionosphere presented by Haerendel and Eccles (1992), to explain the partial contribution of the divergence to the development of the pre-reversal electric field. The theory predicts an enhanced zonal electric field and hence a vertical electric field below 300 km as a consequence of the EEJ divergence in the evening. The experimental results of the enhanced echoes from the higher heights of the EEJ region seem to provide evidence that the divergence of the EEJ current can indeed be the driver of the observed scattering region

Adubação verde com gliricidia sepium como fonte permanente de nitrogênio na cultura do coqueiro.

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