Browsing by Subject "CONNECTION"

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  • SECRETO Study Grp; Martinez-Majander, Nicolas; Artto, Ville; Ylikotila, Pauli; von Sarnowski, Bettina; Huhtakangas, Juha; Numminen, Heikki; Jäkälä, Pekka; Putaala, Jukka (2021)
    Objective To assess the association between migraine and cryptogenic ischemic stroke (CIS) in young adults, with subgroup analyses stratified by sex and presence of patent foramen ovale (PFO). Methods We prospectively enrolled 347 consecutive patients aged 18 to 49 years with a recent CIS and 347 age- and sex-matched (+/- 5 years) stroke-free controls. Any migraine and migraine with (MA) and migraine without aura (MO) were identified by a screener, which we validated against a headache neurologist. We used conditional logistic regression adjusting for age, education, hypertension, diabetes, waist-to-hip ratio, physical inactivity, current smoking, heavy drinking, and oral estrogen use to assess independent association between migraine and CIS. The effect of PFO on the association between migraine and CIS was analyzed with logistic regression in a subgroup investigated with transcranial Doppler bubble screen. Results The screener performance was excellent (Cohen kappa > 0.75) in patients and controls. Compared with nonmigraineurs, any migraine (odds ratio [OR] = 2.48, 95% confidence interval [CI] = 1.63-3.76) and MA (OR = 3.50, 95% CI = 2.19-5.61) were associated with CIS, whereas MO was not. The association emerged in both women (OR = 2.97 for any migraine, 95% CI = 1.61-5.47; OR = 4.32 for MA, 95% CI = 2.16-8.65) and men (OR = 2.47 for any migraine, 95% CI = 1.32-4.61; OR = 3.61 for MA, 95% CI = 1.75-7.45). Specifically for MA, the association with CIS remained significant irrespective of PFO. MA prevalence increased with increasing magnitude of the right-to-left shunt in patients with PFO. Interpretation MA has a strong association with CIS in young patients, independent of vascular risk factors and presence of PFO. ANN NEUROL 2020
  • Sanchez-Diaz, E.; Rouillard, A. P.; Lavraud, B.; Kilpua, E.; Davies, J. A. (2019)
    The release of density structures at the tip of the coronal helmet streamers, likely as a consequence of magnetic reconnection, contributes to the mass flux of the slow solar wind (SSW). In situ measurements in the vicinity of the heliospheric plasma sheet of the magnetic field, protons, and suprathermal electrons reveal details of the processes at play during the formation of density structures near the Sun. In a previous article, we exploited remote-sensing observations to derive a 3D picture of the dynamic evolution of a streamer. We found evidence of the recurrent and continual release of dense blobs from the tip of the streamers. In the present paper, we interpret in situ measurements of the SSW during solar maximum. Through both case and statistical analysis, we show that in situ signatures (magnetic field magnitude, smoothness and rotation, proton density, and suprathermal electrons, in the first place) are consistent with the helmet streamers producing, in alternation, high-density regions (mostly disconnected) separated by magnetic flux ropes (mostly connected to the Sun). This sequence of emission of dense blobs and flux ropes also seems repeated at smaller scales inside each of the high-density regions. These properties are further confirmed with in situ measurements much closer to the Sun using Helios observations. We conclude on a model for the formation of dense blobs and flux ropes that explains both the in situ measurements and the remote-sensing observations presented in our previous studies.
  • Riechers, Maraja; Loos, Jacqueline; Balazsi, Agnes; Garcia-Llorente, Marina; Bieling, Claudia; Burgos-Ayala, Aracely; Chakroun, Leila; Mattijssen, Thomas J. M.; Muhr, Maximilian M.; Perez-Ramirez, Irene; Raatikainen, Kaisa J.; Rana, Sakshi; Richardson, Miles; Rosengren, Linda; West, Simon (2021)
    This perspective paper synthesises the special issue 'Human-nature connectedness as a leverage point for sustainability transformation'. Based on the articles in this special issue, we aim to foster the operationalisation of the leverage points perspective to shape human-nature relations to enable sustainability transformations. Specifically, we draw on four key advantages of the leverage points perspective: (i) the explicit recognition of deep leverage points; (ii) the ability to examine the interactions between shallow and deep system changes; (iii) the combination of causal and teleological modes of research; and (iv) the ability to function as a methodological boundary object. The contributions to this special issue revealed three deep leverage points addressing paradigm shifts in research and beyond: relational thinking and values, stewardship philosophy and shifting the economic growth paradigm to focus on human well-being. We highlight interlinkages between leverage points to further strengthen the transformative potential of interventions that aim at triggering shifts in our understanding about human-nature relations. Further, we show a way to bridge causal and teleological approaches by envisioning desired futures. Lastly, we emphasise the potential of arts-based methodologies, including participatory, transdisciplinary research to foster sustainability transformation and how this can be combined within the leverage points perspective.
  • Sanchez-Diaz, E.; Rouillard, A. P.; Davies, J. A.; Lavraud, B.; Sheeley, N. R.; Pinto, R. F.; Kilpua, E.; Plotnikov, I.; Genot, V. (2017)
    The origin of the slow solar wind is still a topic of much debate. The continual emergence of small transient structures from helmet streamers is thought to constitute one of the main sources of the slow wind. Determining the height at which these transients are released is an important factor in determining the conditions under which the slow solar wind forms. To this end, we have carried out a multipoint analysis of small transient structures released from a north-south tilted helmet streamer into the slow solar wind over a broad range of position angles during Carrington Rotation 2137. Combining the remote-sensing observations taken by the Solar-TErrestrial RElations Observatory (STEREO) mission with coronagraphic observations from the SOlar and Heliospheric Observatory (SOHO) spacecraft, we show that the release of such small transient structures (often called blobs), which subsequently move away from the Sun, is associated with the concomitant formation of transient structures collapsing back toward the Sun; the latter have been referred to by previous authors as "raining inflows." This is the first direct association between outflowing blobs and raining inflows, which locates the formation of blobs above the helmet streamers and gives strong support that the blobs are released by magnetic reconnection.
  • Erfanianfar, G.; Finoguenov, A.; Furnell, K.; Popesso, P.; Biviano, A.; Wuyts, S.; Collins, C. A.; Mirkazemi, M.; Comparat, J.; Khosroshahi, H.; Nandra, K.; Capasso, R.; Rykoff, E.; Wilman, D.; Merloni, A.; Clerc, N.; Salvato, M.; Chitham, J. I.; Kelvin, L. S.; Gozaliasl, G.; Weijmans, A.; Brownstein, J.; Egami, E.; Pereira, M. J.; Schneider, D. P.; Kirkpatrick, C.; Damsted, S.; Kukkola, A. (2019)
    We present the brightest cluster galaxies (BCGs) catalog for SPectroscoic IDentification of eROSITA Sources (SPIDERS) DR14 cluster program value-added catalog. We list the 416 BCGs identified as part of this process, along with their stellar mass, star formation rates (SFRs), and morphological properties. We identified the BCGs based on the available spectroscopic data from SPIDERS and photometric data from SDSS. We computed stellar masses and SFRs of the BCGs on the basis of SDSS, WISE, and GALEX photometry using spectral energy distribution fitting. Morphological properties for all BCGs were derived by Sersic profile fitting using the software package SIGMA in different optical bands (g,r,i). We combined this catalog with the BCGs of galaxy groups and clusters extracted from the deeper AEGIS, CDFS, COSMOS, XMM-CFHTLS, and XMM-XXL surveys to study the stellar mass-halo mass relation using the largest sample of X-ray groups and clusters known to date. This result suggests that the mass growth of the central galaxy is controlled by the hierarchical mass growth of the host halo. We find a strong correlation between the stellar mass of BCGs and the mass of their host halos. This relation shows no evolution since z similar to 0.65. We measure a mean scatter of 0.21 and 0.25 for the stellar mass of BCGs in a given halo mass at low (0.1 <z <0.3) and high (0.3 <z <0.65) redshifts, respectively. We further demonstrate that the BCG mass is covariant with the richness of the host halos in the very X-ray luminous systems. We also find evidence that part of the scatter between X-ray luminosity and richness can be reduced by considering stellar mass as an additional variable.
  • Viitanen, A.; Allevato, V.; Finoguenov, A.; Bongiorno, A.; Cappelluti, N.; Gilli, R.; Miyaji, T.; Salvato, M. (2019)
    Aims. We study the spatial clustering of 632 (1130) XMM-COSMOS active galactic nuclei (AGNs) with known spectroscopic or photometric redshifts in the range z = [0.1-2.5] in order to measure the AGN bias and estimate the typical mass of the hosting dark matter (DM) halo as a function of AGN host galaxy properties. Methods. We created AGN subsamples in terms of stellar mass, M-*, and specific black hole accretion rate, L-X/M-*, to study how AGN environment depends on these quantities. Further, we derived the M-*-M-halo relation for our sample of XMM-COSMOS AGNs and compared it to results in literature for normal non-active galaxies. We measured the projected two-point correlation function w(p)(r(p)) using both the classic and the generalized clustering estimator, based on photometric redshifts, as probability distribution functions in addition to any available spectroscopic redshifts. We measured the large-scale (r(p) greater than or similar to 1h(-1) Mpc) linear bias b by comparing the clustering signal to that expected of the underlying DM distribution. The bias was then related to the typical mass of the hosting halo M-halo of our AGN subsamples. Since M-* and L-X/M-* are correlated, we matched the distribution in terms of one quantity and we split the distribution in the other. Results. For the full spectroscopic AGN sample, we measured a typical DM halo mass of log(M-halo/h(-1)M(circle dot)) = 12.79(-0.43)(+0.26), similar to galaxy group environments and in line with previous studies for moderate-luminosity X-ray selected AGN. We find no significant dependence on specific accretion rate L-X/M-* with log(M-halo/h(-1)M(circle dot)) = 13.06(-0.38)(+0.23) and log(M-halo/h(-1)M(circle dot)) = 12.97(-1.26)(+0.39) for low and high Lx/M, subsamples, respectively. We also find no difference in the hosting halos in terms of M, with log(M-halo/h(-1)M(circle dot)) = 12.93(-0.62)(+0.31) (low) and log(M-halo/h(-1)M(circle dot)) = 12.90(-0.62)(+0.30) (high). By comparing the M-*-M-halo relation derived for XMM-COSMOS AGN subsamples with what is expected for normal non-active galaxies by abundance matching and clustering results, we find that the typical DM halo mass of our high M-* AGN subsample is similar to that of non-active galaxies. However, AGNs in our low M-* subsample are found in more massive halos than non-active galaxies. By excluding AGNs in galaxy groups from the clustering analysis, we find evidence that the result for low M-* may be due to larger fraction of AGNs as satellites in massive halos.
  • Wagner, Andreas; Asvestari, Eleanna; Temmer, Manuela; Heinemann, S. G.; Pomoell, Jens (2022)
    Context. In this paper, we present a validation scheme to investigate the quality of coronal magnetic field models, which is based on comparisons with observational data from multiple sources. Aims. Many of these coronal models may use a range of initial parameters that produce a large number of physically reasonable field configurations. However, that does not mean that these results are reliable and comply with the observations. With an appropriate validation scheme, which is the aim of this work, the quality of a coronal model can be assessed. Methods. The validation scheme was developed with the example of the EUropean Heliospheric FORecasting Information Asset (EUHFORIA) coronal model. For observational comparison, we used extreme ultraviolet and white-light data to detect coronal features on the surface (open magnetic field areas) and off-limb (streamer and loop) structures from multiple perspectives (Earth view and the Solar Terrestrial Relations Observatory - STEREO). The validation scheme can be applied to any coronal model that produces magnetic field line topology. Results. We show its applicability by using the validation scheme on a large set of model configurations, which can be efficiently reduced to an ideal set of parameters that matches best with observational data. Conclusions. We conclude that by using a combined empirical visual classification with a mathematical scheme of topology metrics, a very efficient and objective quality assessment for coronal models can be performed.