440 research outputs found

    Long-term photometric behaviour of XZ Dra Binarity or magnetic cycle of a Blazhko type RRab star

    Full text link
    The extended photometry available for XZ Dra, a Blazhko type RR Lyrae star, makes it possible to study its long-term behavior. It is shown that its pulsation period exhibit cyclic, but not strictly regular variations with approx. 7200 d period. The Blazhko period (approx. 76 d) seems to follow the observed period changes of the fundamental mode pulsation with dP_B/dP_0=7.7 x 10^4 gradient. Binary model cannot explain this order of period change of the Blazhko modulation, nevertheless it can be brought into agreement with the O-C data of the pulsation. The possibility of occurrence of magnetic cycle is raised.Comment: 13 pages, 11 figures (submitted to A&A

    Factors influencing the quality of life of empty nesters: Empirical evidence from Southwest China

    Get PDF
    Quality of life is a widely accepted concept based on the notion that people’s lives have been subject to rapid development and industrialization. This study aims to explore the impact of different factors on the quality of life of empty nesters in Southwest China. The main factors explored are resilience and social supports (SS), highlighted here from different perspectives. Moreover, the correlations between other variables and quality of life are shown here. This study experimented with a hierarchical multiple regression model from survey data with 3583 valid responses. It argued that both resilience and social supports, including family members and friends, are significantly correlated with the Chinese empty nesters’ quality of life. Family support and friend support play a significant mediating role in the association between resilience and quality of life. However, neither government nor nongovernmental support significantly influences the quality of life. Therefore, the hypothetical recommendations of this study have been partially confirmed. The findings of this study provide a more comprehensive understanding of the overall mental and physical health of Chinese empty nesters

    Social Pre-treatment Modulates Attention Allocation to Transient and Stable Object Properties

    Get PDF
    Increasing evidence suggests that ostensive-communicative signals in social learning situations enable observers to focus their attention on the intrinsic features of an object (e.g., color) at the expense of ignoring transient object properties (e.g., location). Here we investigated whether off-line social cues, presented as social primes, have the same power to modulate attention allocation to stable and transient object properties as on-line ostensive-communicative cues. The first part of the experiment consisted of a pre-treatment phase, where adult male participants either received intensive social stimulation or were asked to perform non-social actions. Then, they participated in a change detection test, where they watched pairs of pictures depicting an array of five objects. On the second picture, a change occurred compared to the first picture. One object changed either its location (moving forward or backward) or was replaced by another object, and participants were required to indicate where the change had happened. We found that participants detected the change more successfully if it had happened in the location of the object; however, this difference was reduced following a socially intense pre-treatment phase. The results are discussed in relation to the claims of the natural pedagogy theory

    Investigating magnetic activity in very stable stellar magnetic fields: long-term photometric and spectroscopic study of the fully convective M4 dwarf V374 Peg

    Get PDF
    The ultrafast-rotating (Prot0.44dP_\mathrm{rot}\approx0.44 d) fully convective single M4 dwarf V374 Peg is a well-known laboratory for studying intense stellar activity in a stable magnetic topology. As an observable proxy for the stellar magnetic field, we study the stability of the light curve, and thus the spot configuration. We also measure the occurrence rate of flares and coronal mass ejections (CMEs). We analyse spectroscopic observations, BV(RI)CBV(RI)_C photometry covering 5 years, and additional RCR_C photometry that expands the temporal base over 16 years. The light curve suggests an almost rigid-body rotation, and a spot configuration that is stable over about 16 years, confirming the previous indications of a very stable magnetic field. We observed small changes on a nightly timescale, and frequent flaring, including a possible sympathetic flare. The strongest flares seem to be more concentrated around the phase where the light curve indicates a smaller active region. Spectral data suggest a complex CME with falling-back and re-ejected material, with a maximal projected velocity of \approx675km/s. We observed a CME rate much lower than expected from extrapolations of the solar flare-CME relation to active stars.Comment: 15 figures, 4 tables, accepted for publication in A&

    Az ipari körzettől az innovációs körzetig – az innovációs földrajz első évszázada = From Industrial District to Innovation System – The First Century of the Geography of Innovation

    Get PDF
    A regionális reziliencia egyik meghatározó tényezőjét a helyi innovációs potenciál és aktivitás adja, amelynek területi alapú vizsgálata szorosan kapcsolódik a földrajztudományhoz, az innovációföldrajzhoz. Az innovációföldrajz új tudományterület, amelynek keretében alapfeltevéseiben is különböző elméletek születtek az innováció megértésére. Kutatási célunk, hogy feltárjuk és egyes dimenzióiban számszerűsítsük az innováció kérdéskörének elmélettörténeti dinamikáját, rámutatva a paradigmák változásaira, az elmúlt két évtized elméleteire. Bemutatjuk a neoklasszikus elméleti modellek tökéletesen informált és racionális, optimalizáló vállalatait, a helyelméleteket, az ipari körzetek helyhez kötött elméleteit és a háború utáni keynesiánus területi tervezési politikához kapcsolódó növekedési pólusok teóriáját. Elemzésünk kiterjed továbbá a tanuló régiók, a hálózatok, valamint az innovációs rendszerek kérdéskörére is, e szempontok szintén kapcsolódnak az innovációs geográfia vizsgálati horizontjához. E megközelítések tanulságai, valamint a földrajz kapcsolódó területeinek történeti és big data alapú elemzése hasznos lehet a területi tervezéssel foglalkozó szakemberek számára

    Ultrasound and dynamic functional imaging in vascular cognitive impairment and Alzheimer's disease

    Get PDF
    The vascular contributions to neurodegeneration and neuroinflammation may be assessed by magnetic resonance imaging (MRI) and ultrasonography (US). This review summarises the methodology for these widely available, safe and relatively low cost tools and analyses recent work highlighting their potential utility as biomarkers for differentiating subtypes of cognitive impairment and dementia, tracking disease progression and evaluating response to treatment in various neurocognitive disorders. METHODS: At the 9th International Congress on Vascular Dementia (Ljubljana, Slovenia, October 2015) a writing group of experts was formed to review the evidence on the utility of US and arterial spin labelling (ASL) as neurophysiological markers of normal ageing, vascular cognitive impairment (VCI) and Alzheimer's disease (AD). Original articles, systematic literature reviews, guidelines and expert opinions published until September 2016 were critically analysed to summarise existing evidence, indicate gaps in current knowledge and, when appropriate, suggest standards of use for the most widely used US and ASL applications. RESULTS: Cerebral hypoperfusion has been linked to cognitive decline either as a risk or an aggravating factor. Hypoperfusion as a consequence of microangiopathy, macroangiopathy or cardiac dysfunction can promote or accelerate neurodegeneration, blood-brain barrier disruption and neuroinflammation. US can evaluate the cerebrovascular tree for pathological structure and functional changes contributing to cerebral hypoperfusion. Microvascular pathology and hypoperfusion at the level of capillaries and small arterioles can also be assessed by ASL, an MRI signal. Despite increasing evidence supporting the utility of these methods in detection of microvascular pathology, cerebral hypoperfusion, neurovascular unit dysfunction and, most importantly, disease progression, incomplete standardisation and missing validated cut-off values limit their use in daily routine. CONCLUSIONS: US and ASL are promising tools with excellent temporal resolution, which will have a significant impact on our understanding of the vascular contributions to VCI and AD and may also be relevant for assessing future prevention and therapeutic strategies for these conditions. Our work provides recommendations regarding the use of non-invasive imaging techniques to investigate the functional consequences of vascular burden in dementia

    Selective Sirt2 inhibition by ligand-induced rearrangement of the active site.

    Get PDF
    Sirtuins are a highly conserved class of NAD(+)-dependent lysine deacylases. The human isotype Sirt2 has been implicated in the pathogenesis of cancer, inflammation and neurodegeneration, which makes the modulation of Sirt2 activity a promising strategy for pharmaceutical intervention. A rational basis for the development of optimized Sirt2 inhibitors is lacking so far. Here we present high-resolution structures of human Sirt2 in complex with highly selective drug-like inhibitors that show a unique inhibitory mechanism. Potency and the unprecedented Sirt2 selectivity are based on a ligand-induced structural rearrangement of the active site unveiling a yet-unexploited binding pocket. Application of the most potent Sirtuin-rearranging ligand, termed SirReal2, leads to tubulin hyperacetylation in HeLa cells and induces destabilization of the checkpoint protein BubR1, consistent with Sirt2 inhibition in vivo. Our structural insights into this unique mechanism of selective sirtuin inhibition provide the basis for further inhibitor development and selective tools for sirtuin biology

    EI Eridani: a star under the influence -- The effect of magnetic activity in the short and long term

    Get PDF
    We use our photometric time series of more than forty years to analyze the long-term behaviour of EI Eri. Flare activity is investigated using space-borne photometric data obtained with TESS. The MUSICOS campaign aimed to achieve high-resolution spectroscopic observations from many sites around the globe, so that uninterrupted phase coverage of EI Eri became available. We use these data to reconstruct successive surface temperature maps of the star in order to study the changes of starspots on a very short timescale. We use long-term, seasonal period analysis of our photometric time series to study changes in the rotational period. Short-term Fourier-transform is also applied to look for activity cycle-like changes. We also study the phase and frequency distribution of hand-selected flares. We apply our multi-line Doppler imaging code to reconstruct four consecutive Doppler images. These images are also used to measure surface differential rotation by our cross-correlation technique. In addition, we carry out tests to demonstrate how Doppler imaging is affected by the fact that the data came from several different instruments with different spectral resolutions. Seasonal period analysis of the light curve reveals a smooth, significant change in period, possibly indicating the evolution of active latitudes. Temperature curves from BVB-V and VIV-I show slight differences, indicating the activity of EI Eri is spot dominated. Short-term Fourier transform reveals smoothly changing cycles between 4.5--5.5 and 8.9--11.6 years. The time-resolved spotted surface of EI Eri from Doppler imaging enabled us to follow the evolution of the different surface features. Cross-correlating the consecutive Doppler maps reveal surface shear of α=0.036±0.007\alpha=0.036\pm0.007. Our tests validate our approach and show that the surface temperature distribution is adequately reconstructed by our method.Comment: 14 pages, 13 figures, A&A accepte
    corecore