Abstract
A hierarchical Bayesian model is applied to the Cosmicflows-3 catalogue of galaxy distances in order to derive the peculiar velocity field and distribution of matter within z ∼ 0.054. The ...model assumes the ΛCDM model within the linear regime and includes the fit of the galaxy distances together with the underlying density field. By forward modelling the data, the method is able to mitigate biases inherent to peculiar velocity analyses, such as the Homogeneous Malmquist bias or the lognormal distribution of peculiar velocities. The statistical uncertainty on the recovered velocity field is about 150 km s−1 depending on the location, and we study systematics coming from the selection function and calibration of distance indicators. The resulting velocity field and related density fields recover the cosmography of the Local Universe which is presented in an unprecedented volume of our Universe 10 times larger than previously reached. This methodology opens the doors to reconstruction of initial conditions for larger and more accurate constrained cosmological simulations. This work is also preparatory to larger peculiar velocity data sets coming from Wallaby, TAIPAN, or LSST.
The current study focuses on the association between social anxiety (e.g. fear of social interactions or negative judgment by others) and intimate loneliness (lacking meaningful relationships, i.e. ...having low quantity/quality of intimate companionship) in older and younger adults. We assessed whether social anxiety, a factor which hampers intimacy, may be associated with intimate loneliness to a greater extent in older adults versus younger adults.
Measures of loneliness (Revised UCLA loneliness scale) and social anxiety (Leibowitz social anxiety scale) were obtained from 342 participants (220 younger adults, age = 19-40, and 122 older adults, age = 61-89).
Age differences were evident for non-intimate types of loneliness but not for intimate loneliness. Further, older adults were less socially anxious. Critically, the strength of the social anxiety-intimate loneliness link was more robust among older adults. Effects remained significant after controlling for demographic and computer/social media variables.
Older adults with high levels of social anxiety displayed greater intimate loneliness relative to younger adults. On a theoretical level, the results reveal that the pruning mechanism of investing more in closer and more rewarding relationships among older adults may be challenged under high social anxiety. The results suggest that older adults with higher intimate loneliness may benefit from interventions aimed at decreasing their social anxiety.
We use a cosmological simulation of the formation of the Local Group to explore the origin of age and metallicity gradients in dwarf spheroidal galaxies. We find that a number of simulated dwarfs ...form ‘outside-in’, with an old, metal-poor population that surrounds a younger, more concentrated metal-rich component, reminiscent of dwarf spheroidals like Sculptor or Sextans. We focus on a few examples where stars form in two populations distinct in age in order to elucidate the origin of these gradients. The spatial distributions of the two components reflect their diverse origin; the old stellar component is assembled through mergers, but the young population forms largely in situ. The older component results from a first episode of star formation that begins early but is quickly shut off by the combined effects of stellar feedback and reionization. The younger component forms when a late accretion event adds gas and reignites star formation. The effect of mergers is to disperse the old stellar population, increasing their radius and decreasing their central density relative to the young population. We argue that dwarf–dwarf mergers offer a plausible scenario for the formation of systems with multiple distinct populations and, more generally, for the origin of age and metallicity gradients in dwarf spheroidals.
We contend that a single power-law halo mass distribution is appropriate for direct matching to the stellar masses of observed Local Group dwarf galaxies, allowing the determination of the slope of ...the stellar mass-halo mass relation for low-mass galaxies. Errors in halo masses are well defined as the Poisson noise of simulated Local Group realizations, which we determine using local volume simulations. For the stellar mass range 10 super(7) M sub(middot in circle) < Mlow * < 10 super(8) M sub(middot in circle), for which we likely have a complete census of observed galaxies, we find that the stellar mass-halo mass relation follows a power law with slope of 3.1, significantly steeper than most values in the literature. This steep relation between stellar and halo masses would indicate that Local Group dwarf galaxies are hosted by dark matter halos with a small range of mass. Our methodology is robust down to the stellar mass to which the census of observed Local Group galaxies is complete, but the significant uncertainty in the currently measured slope of the stellar-to-halo mass relation will decrease dramatically if the Local Group completeness limit was 10 super(6.5) M sub(middot in circle) or below, highlighting the importance of pushing such limit to lower masses and larger volumes.
People with posttraumatic stress disorder (PTSD) may have cognitive decline, a risk which can be particularly threatening at old age. However, it is yet unclear whether initial cognitive decline ...renders one more susceptible to subsequent PTSD following exposure to traumatic events, whether initial PTSD precedes cognitive decline or whether the effects are reciprocal.
This study examined the bidirectional longitudinal associations between cognitive function and PTSD symptoms and whether this association is mediated by depressive symptoms.
The study used data from two waves of the Israeli component of the Survey of Health, Ageing, and Retirement in Europe (SHARE), collected in 2013 and 2015. This study focused on adults aged 50 years and above (N = 567, mean age = 65.9 years). Each wave used three measures of cognition (recall, fluency, and numeracy) and PTSD symptoms following exposure to war-related events. Data were analyzed using mediation analysis with path analysis.
Initial PTSD symptoms predicted cognitive decline in recall and fluency two years later, while baseline cognitive function did not impact subsequent PTSD symptoms. Partial mediation showed that older adults with more PTSD symptoms had higher depressive symptoms, which in turn were linked to subsequent cognitive decline across all three measures.
This study reveals that PTSD symptoms are linked with subsequent cognitive decline, supporting approaches addressing this direction. It further indicates that part of this effect can be explained by increased depressive symptoms. Thus, treatment for depressive symptoms may help reduce cognitive decline due to PTSD.
Abstract
Motivated by the ${\sim }7{{\ \rm per\ cent}}$ dipole anisotropy in the distribution of ultra-high-energy cosmic rays (UHECRs) above 8 EeV, we explore the anisotropy induced by the ...large-scale structure (LSS), using constrained simulations of the local Universe and taking into account the effect of magnetic fields. The value of the intergalactic magnetic field (IGMF) is critical as it determines the UHECR cosmic horizon. We calculate the UHECR sky maps for different values of the IGMF variance and show the effect of the UHECR horizon on the observed anisotropy. The footprint of the local (≲ 350 Mpc) Universe on the UHECR background, a small angular scale enhancement in the Northern hemisphere, is seen. At 11.5 EeV (the median value of the energy bin at which the dipole has been reported), the LSS-induced dipole amplitude is $A_1\sim 10{{\ \rm per\ cent}}$, for IGMF in the range 0.3–3 nG for protons, helium and nitrogen, compatible with the rms value derived from the cosmic power spectrum. However at these energies, the UHECRs are also influenced by the Galactic magnetic field and we discuss its effect on the LSS-induced anisotropy.
The p53 pathway is pivotal in tumor suppression. Cellular p53 activity is subject to tight regulation, in which the two related proteins Mdm2 and Mdm4 have major roles. The delicate interplay between ...the levels of Mdm2, Mdm4 and p53 is crucial for maintaining proper cellular homeostasis. microRNAs (miRNAs) are short non-coding RNAs that downregulate the level and translatability of specific target mRNAs. We report that miR-661, a primate-specific miRNA, can target both Mdm2 and Mdm4 mRNA in a cell type-dependent manner. miR-661 interacts with Mdm2 and Mdm4 RNA within living cells. The inhibitory effect of miR-661 is more prevalent on Mdm2 than on Mdm4. Interestingly, the predicted miR-661 targets in both mRNAs reside mainly within Alu elements, suggesting a primate-specific mechanism for regulatory diversification during evolution. Downregulation of Mdm2 and Mdm4 by miR-661 augments p53 activity and inhibits cell cycle progression in p53-proficient cells. Correspondingly, low miR-661 expression correlates with bad outcome in breast cancers that typically express wild-type p53. In contrast, the miR-661 locus tends to be amplified in tumors harboring p53 mutations, and miR-661 promotes migration of cells derived from such tumors. Thus, miR-661 may either suppress or promote cancer aggressiveness, depending on p53 status.
The velocity shear tensor: tracer of halo alignment Libeskind, Noam I; Hoffman, Yehuda; Forero-Romero, Jaime ...
Monthly Notices of the Royal Astronomical Society,
01/2013, Letnik:
428, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The alignment of dark matter (DM) haloes and the surrounding large-scale structure (LSS) is examined in the context of the cosmic web. Halo spin, shape and the orbital angular momentum of subhaloes ...are investigated relative to the LSS using the eigenvectors of the velocity shear tensor evaluated on a grid with a scale of 1 Mpc h
−1, deep within the non-linear regime. Knots, filaments, sheets and voids are associated with regions that are collapsing along 3, 2, 1 or 0 principal directions simultaneously. Each halo is tagged with a web classification (i.e. knot halo, filament halo, etc.) according to the nature of the collapse at the halo position. The full distribution of shear eigenvalues is found to be substantially different from that tagged to haloes, indicating that the observed velocity shear is significantly biased. We find that larger mass haloes live in regions where the shear is more isotropic, namely the expansion or collapse is more spherical. A correlation is found between the halo shape and the eigenvectors of the shear tensor, with the longest (shortest) axis of the halo shape being aligned with the slowest (fastest) collapsing eigenvector. This correlation is web independent, suggesting that the velocity shear is a fundamental tracer of the halo alignment. A similar result is found for the alignment of halo spin with the cosmic web. It has been shown that high-mass haloes exhibit a spin flip with respect to the LSS: we find that the mass at which this spin flip occurs is web dependent and not universal as suggested previously. Although weaker than haloes, subhalo orbits too exhibit an alignment with the LSS, providing a possible insight into the highly correlated corotation of the Milky Way's satellite system. The present study suggests that the velocity shear tensor constitutes the natural framework for studying the directional properties of the non-linear LSS and those of haloes and galaxies.
We revise the mass estimate of the Local Group (LG) when dark energy (in the form of the cosmological constant) is incorporated into the timing argument (TA) mass estimator for the LG. Assuming the ...age of the Universe and the cosmological constant according to the recent values from the Planck cosmic microwave background experiment, we find the mass of the LG to be M
TAΛ = (4.73 ± 1.03) × 1012 M which is 13 per cent higher than the classical TA mass estimate. This partly explains the discrepancy between earlier results from Lambda cold dark matter simulations and the classical TA. When a similar analysis is performed on 16 LG-like galaxy pairs from the Constrained Local Universe Simulations, we find that the scatter in the ratio of the virial to the TA estimated mass is given by M
vir/M
TAΛ = 1.04 ± 0.16. Applying it to the LG mass estimation we find a calibrated M
vir = (4.92 ± 1.08(obs.) ± 0.79(sys.)) × 1012 M.
Identification of human satellite cells that fulfill muscle stem cell criteria is an unmet need in regenerative medicine. This hurdle limits understanding how closely muscle stem cell properties are ...conserved among mice and humans and hampers translational efforts in muscle regeneration. Here, we report that PAX7 satellite cells exist at a consistent frequency of 2–4 cells/mm of fiber in muscles of the human trunk, limbs, and head. Xenotransplantation into mice of 50–70 fiber-associated, or 1,000–5,000 FACS-enriched CD56+/CD29+ human satellite cells led to stable engraftment and formation of human-derived myofibers. Human cells with characteristic PAX7, CD56, and CD29 expression patterns populated the satellite cell niche beneath the basal lamina on the periphery of regenerated fibers. After additional injury, transplanted satellite cells robustly regenerated to form hundreds of human-derived fibers. Together, these findings conclusively delineate a source of bona-fide endogenous human muscle stem cells that will aid development of clinical applications.
•CD56 and CD29 mark PAX7 satellite cells in diverse human muscles•Transplanted human satellite cells engraft, self-renew, and regenerate•Human adult muscle stem cells reside within the CD56+/CD29+ satellite cell pool
In this article Pomerantz and colleagues demonstrate that human skeletal muscle stem cells reside within the satellite cell pool at similar frequencies in diverse adult muscles and engraft, populate the stem cell niche, and regenerate after transplantation.
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