926 research outputs found

    Supersaturated dispersions of rod-like viruses with added attraction

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    The kinetics of isotropic-nematic (I-N) and nematic-isotropic (N-I) phase transitions in dispersions of rod-like {\it fd}-viruses are studied. Concentration quenches were applied using pressure jumps in combination with polarization microscopy, birefringence and turbidity measurements. The full biphasic region could be accessed, resulting in the construction of a first experimental analogue of the bifurcation diagram. The N-I spinodal points for dispersions of rods with varying concentrations of depletion agents (dextran) were obtained from orientation quenches, using cessation of shear flow in combination with small angle light scattering. We found that the location of the N-I spinodal point is independent of the attraction, which was confirmed by theoretical calculations. Surprisingly, the experiments showed that also the absolute induction time, the critical nucleus and the growth rate are insensitive of the attraction, when the concentration is scaled to the distance to the phase boundaries.Comment: 13 pages, 14 figures. accepted in Phsical Review

    Transport and magnetization dynamics in a superconductor/single-molecule magnet/superconductor junction

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    We study dc-transport and magnetization dynamics in a junction of arbitrary transparency consisting of two spin-singlet superconducting leads connected via a single classical spin precessing at the frequency Ω\Omega. The presence of the spin in the junction provides different transmission amplitudes for spin-up and spin-down quasiparticles as well as a time-dependent spin-flip transmission term. For a phase biased junction, we show that a steady-state superconducting charge current flows through the junction and that an out-of-equilibrium circularly polarized spin current, of frequency Ω\Omega, is emitted in the leads. Detailed understanding of the charge and spin currents is obtained in the entire parameter range. In the adiabatic regime, Ω2Δ\hbar \Omega \ll 2\Delta where Δ\Delta is the superconducting gap, and for high transparencies of the junction, a strong suppression of the current takes place around \vp \approx 0 due to an abrupt change in the occupation of the Andreev bound-states. At higher values of the phase and/or precession frequency, extended (quasi-particle like) states compete with the bound-states in order to carry the current. Well below the superconducting transition, these results are shown to be weakly affected by the back-action of the spin current on the dynamics of the precessing spin. Indeed, we show that the Gilbert damping due to the quasi-particle spin current is strongly suppressed at low-temperatures, which goes along with a shift of the precession frequency due to the condensate. The results obtained may be of interest for on-going experiments in the field of molecular spintronics.Comment: 19 pages, 13 figures (v3) Minor modifications per referee's comments. No change in results. (v2) 2 authors added, 1 reference added (Ref. 25), no change in the text and result

    Exploring the nature of visual fixations on other pedestrians

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    How we look at other people may affect conclusions drawn about the effect of changes in lighting when this task needs to be done after dark. This paper reports further analysis of the distance and duration of fixation on other pedestrians, updating a previous review by considering a greater number of fixations and by examining the influence on these of other characteristics such as the relative direction of travel. This analysis provides further support for a tendency to fixate others at a distance of 15 m and for a duration of 500 ms

    Alpha-Synuclein Expression in the Oligodendrocyte Lineage: an In Vitro and In Vivo Study Using Rodent and Human Models.

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    In this study, we sought evidence for alpha-synuclein (ASYN) expression in oligodendrocytes, as a possible endogenous source of ASYN to explain its presence in glial inclusions found in multiple system atrophy (MSA) and Parkinson's disease (PD). We identified ASYN in oligodendrocyte lineage progenitors isolated from the rodent brain, in oligodendrocytes generated from embryonic stem cells, and in induced pluripotent stem cells produced from fibroblasts of a healthy individual and patients diagnosed with MSA or PD, in cultures in vitro. Notably, we observed a significant decrease in ΑSYN during oligodendrocyte maturation. Additionally, we show the presence of transcripts in PDGFRΑ/CD140a(+) cells and SOX10(+) oligodendrocyte lineage nuclei isolated by FACS from rodent and human healthy and diseased brains, respectively. Our work identifies ASYN in oligodendrocyte lineage cells, and it offers additional in vitro cellular models that should provide significant insights of the functional implication of ASYN during oligodendrocyte development and disease

    Gaze direction when driving after dark on main and residential roads: Where is the dominant location?

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    CIE JTC-1 has requested data regarding the size and shape of the distribution of drivers’ eye movement in order to characterise their visual adaptation. This article reports the eye movement of drivers along two routes in Berlin after dark, a main road and a residential street, captured using eye tracking. It was found that viewing behaviour differed between the two types of road. On the main road eye movement was clustered within a circle of approximately 10° diameter, centred at the horizon of the lane. On the residential street eye movement is clustered slightly (3.8°) towards the near side; eye movements were best captured with either an ellipse of approximate axes 10° vertical and 20° horizontal, centred on the lane ahead, or a 10° circle centred 3.8° towards the near side. These distributions reflect a driver’s tendency to look towards locations of anticipated hazards

    Non-equilibrium effects in a Josephson junction coupled to a precessing spin

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    We present a theoretical study of a Josephson junction consisting of two s-wave superconducting leads coupled over a classical spin. When an external magnetic field is applied, the classical spin will precess with the Larmor frequency. This magnetically active interface results in a time-dependent boundary condition with different tunneling amplitudes for spin-up and spin-down quasiparticles and where the precession produces spin-flip scattering processes. We show that as a result, the Andreev states develop sidebands and a non-equilibrium population which depend on the precession frequency and the angle between the classical spin and the external magnetic field. The Andreev states lead to a steady-state Josephson current whose current-phase relation could be used for characterizing the precessing spin. In addition to the charge transport, a magnetization current is also generated.This spin current is time-dependent and its polarization axis rotates with the same precession frequency as the classical spin.Comment: 20 pages, 26 figure

    A novel long non-coding natural antisense RNA is a negative regulator of Nos1 gene expression

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    Long non-coding natural antisense transcripts (NATs) are widespread in eukaryotic species. Although recent studies indicate that long NATs are engaged in the regulation of gene expression, the precise functional roles of the vast majority of them are unknown. Here we report that a long NAT (Mm-antiNos1 RNA) complementary to mRNA encoding the neuronal isoform of nitric oxide synthase (Nos1) is expressed in the mouse brain and is transcribed from the non-template strand of the Nos1 locus. Nos1 produces nitric oxide (NO), a major signaling molecule in the CNS implicated in many important functions including neuronal differentiation and memory formation. We show that the newly discovered NAT negatively regulates Nos1 gene expression. Moreover, our quantitative studies of the temporal expression profiles of Mm-antiNos1 RNA in the mouse brain during embryonic development and postnatal life indicate that it may be involved in the regulation of NO-dependent neurogenesis

    Hyperthyroidism as a late effect in childhood cancer survivors-an Adult Life after Childhood Cancer in Scandinavia (ALiCCS) study

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    Background: Hyperthyroidism is a rare disorder which may negatively affect health and quality of life. Its occurrence in childhood cancer survivors has not previously been investigated in detail. Material and methods: In the hospital registers of the five Nordic countries, 32,944 childhood cancer survivors and 212,675 population comparisons were followed for the diagnosis of hyperthyroidism. Hospitalisation rates, standardised hospitalisation rate ratios and absolute excess risks were calculated with 95% confidence intervals (CI). Results: Hyperthyroidism was diagnosed in 131 childhood cancer survivors, yielding an overall relative risk of 1.6 (95% CI: 1.3-1.9) compared with population comparisons. The risk was greatest 1-5 years after the diagnosis of cancer and in survivors of thyroid cancers, neuroblastomas, acute lymphoblastic leukaemia and Hodgkin lymphoma. Sixty-seven percent of survivors with hyperthyroidism had tumours located in the head, neck or upper body and half of survivors with hyperthyroidism were irradiated with 77% of them in the head and neck area. Conclusion: Childhood cancer survivors are at an increased risk of hyperthyroidism, potentially resulting in non-endocrine morbidity.Peer reviewe
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