| 1. |
- Beale, M. A., et al.
(författare)
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Global phylogeny of Treponema pallidum lineages reveals recent expansion and spread of contemporary syphilis
- 2021
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Ingår i: Nature Microbiology. - : Springer Science and Business Media LLC. - 2058-5276. ; 6:12, s. 1549-
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Tidskriftsartikel (refereegranskat)abstract
- Syphilis, which is caused by the sexually transmitted bacterium Treponema pallidum subsp. pallidum, has an estimated 6.3 million cases worldwide per annum. In the past ten years, the incidence of syphilis has increased by more than 150% in some high-income countries, but the evolution and epidemiology of the epidemic are poorly understood. To characterize the global population structure of T. pallidum, we assembled a geographically and temporally diverse collection of 726 genomes from 626 clinical and 100 laboratory samples collected in 23 countries. We applied phylogenetic analyses and clustering, and found that the global syphilis population comprises just two deeply branching lineages, Nichols and SS14. Both lineages are currently circulating in 12 of the 23 countries sampled. We subdivided T. p.pallidum into 17 distinct sublineages to provide further phylodynamic resolution. Importantly, two Nichols sublineages have expanded clonally across 9 countries contemporaneously with SS14. Moreover, pairwise genome analyses revealed examples of isolates collected within the last 20 years from 14 different countries that had genetically identical core genomes, which might indicate frequent exchange through international transmission. It is striking that most samples collected before 1983 are phylogenetically distinct from more recently isolated sublineages. Using Bayesian temporal analysis, we detected a population bottleneck occurring during the late 1990s, followed by rapid population expansion in the 2000s that was driven by the dominant T. pallidum sublineages circulating today. This expansion may be linked to changing epidemiology, immune evasion or fitness under antimicrobial selection pressure, since many of the contemporary syphilis lineages we have characterized are resistant to macrolides. Global syphilis prevalence has been increasing. Sequencing and analysis of a global collection of 726 Treponema pallidum samples reveal globally circulating lineages linked to a rapid expansion occurring since the end of the twentieth century.
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| 2. |
- Stroganova, T. A., et al.
(författare)
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High-frequency oscillatory response to illusory contour in typically developing boys and boys with autism spectrum disorders
- 2012
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Ingår i: Cortex. - : Elsevier BV. - 0010-9452. ; 48:6, s. 701-717
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Tidskriftsartikel (refereegranskat)abstract
- Illusory contour (IC) perception, a fruitful model for studying the automatic contextual integration of local image features, can be used to investigate the putative impairment of such integration in children with autism spectrum disorders (ASD). We used the illusory Kanizsa square to test how the phase-locked (PL) gamma and beta electroencephalogram (EEG) responses of typically developing (TD) children aged 3-7 years and those with ASD were modulated by the presence of IC in the image. The PL beta and gamma activity strongly differentiated between IC and control figures in both groups of children (IC effect). However, the timing, topography, and direction of the IC effect differed in TD and ASD children. Between 40 msec and 120 msec after stimulus onset, both groups demonstrated lower power of gamma oscillations at occipital areas in response to IC than in response to the control figure. In TD children, this relative gamma suppression was followed by relatively higher parieto-occipital gamma and beta responses to IC within 120-270 msec after stimulus onset. This second stage of IC processing was absent in children with ASD. Instead, their response to IC was characterized by protracted (40-270 msec) relative reduction of gamma and beta oscillations at occipital areas. We hypothesize that children with ASD rely more heavily on lower-order processing in the primary visual areas and have atypical later stage related to higher-order processes of contour integration. (C) 2011 Elsevier Srl. All rights reserved.
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| 3. |
- Stroganova, Tatiana A, et al.
(författare)
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Inverted event-related potentials response to illusory contour in boys with autism.
- 2007
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Ingår i: Neuroreport. - 0959-4965. ; 18:9, s. 931-5
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Tidskriftsartikel (refereegranskat)abstract
- We examined the hypothesis of lower-level processing abnormalities related to perceptual grouping in boys with autism aged 3-6 years. We investigated event-related potentials response to visual elements that either formed perceptually coherent illusory contour or were arranged in a noncoherent way. The results showed that in healthy boys the illusory contour as compared with control stimulus elicited enhanced negativity of N1 peak (C effect), which has been previously found in adults. Autistic boys demonstrated the reliable inverted illusory contour effect, that is, more positive N1 amplitude to illusory contour. We hypothesized that boys with autism were sensitive to difference between illusory contour and control figures basing on collinearity processing mechanisms implemented in neural circuitry of primary visual cortex.
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| 4. |
- Danilchenko, Boris A, et al.
(författare)
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Self-heating of metallic carbon nanotube bundles in the regime of the Luttinger-liquid conductivity
- 2011
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Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 37:8, s. 710-717
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Tidskriftsartikel (refereegranskat)abstract
- The conductivity of bundles of carbon single-walled nanotubes with metallic conductivity (metallic nanotubes) is investigated over the wide temperature range 4.2-330 K and electrical fields up to 50 V. The usage of short electrical pulses of the duration of 10 ns allowed to avoid an influence of a self-heating of the investigated structures on current-voltage characteristics. It is shown that the temperature dependence of conductivity is described by the power function G proportional to T(alpha). At helium temperatures the asymptotic dependence of current on applied voltage is close to J proportional to V(1+alpha) with alpha = 0.45. From comparison of the obtained results of measurements with calculations, it is shown that the conductivity of nanotube bundles is well described within the theory of the Luttinger-liquid conductivity for one-dimensional conductors. The self-heating of the carbon nanotube bundles was observed in the case of measurements in the regime of dc current. A method for determination of the self-heating temperature of nanotube bundles as a function of an applied electrical field is proposed. The power dependence of the self-heating temperature on voltage T proportional to V(p) with the exponent p = 2.1 was observed above some threshold voltage in the temperature range 4.2-200 K. Above 200 K the exponent decreased down to p = 1.35. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3662331]
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