4,089 research outputs found
Gating of memory encoding of time-delayed cross-frequency MEG networks revealed by graph filtration based on persistent homology
To explain gating of memory encoding, magnetoencephalography (MEG) was analyzed over multi-regional network of negative correlations between alpha band power during cue (cue-alpha) and gamma band power during item presentation (item-gamma) in Remember (R) and No-remember (NR) condition. Persistent homology with graph filtration on alpha-gamma correlation disclosed topological invariants to explain memory gating. Instruction compliance (R-hits minus NR-hits) was significantly related to negative coupling between the left superior occipital (cue-alpha) and the left dorsolateral superior frontal gyri (item-gamma) on permutation test, where the coupling was stronger in R than NR. In good memory performers (R-hits minus false alarm), the coupling was stronger in R than NR between the right posterior cingulate (cue-alpha) and the left fusiform gyri (item-gamma). Gating of memory encoding was dictated by inter-regional negative alpha-gamma coupling. Our graph filtration over MEG network revealed these inter-regional time-delayed cross-frequency connectivity serve gating of memory encoding
Large-scale filamentary structures around the Virgo cluster revisited
We revisit the filamentary structures of galaxies around the Virgo cluster,
exploiting a larger dataset based on the HyperLeda database than previous
studies. In particular, this includes a large number of low-luminosity
galaxies, resulting in better sampled individual structures. We confirm seven
known structures in the distance range 4~~Mpc~ SGY~ 16~
Mpc, now identified as filaments, where SGY is the axis of the supergalactic
coordinate system roughly along the line of sight. The Hubble diagram of the
filament galaxies suggests they are infalling toward the main-body of the Virgo
cluster. We propose that the collinear distribution of giant elliptical
galaxies along the fundamental axis of the Virgo cluster is smoothly connected
to two of these filaments (Leo~II~A and B). Behind the Virgo cluster
(16~~Mpc~ SGY~ 27~~Mpc), we also identify a new filament
elongated toward the NGC 5353/4 group ("NGC 5353/4 filament") and confirm a
sheet that includes galaxies from the W and M clouds of the Virgo cluster ("W-M
sheet"). In the Hubble diagram, the NGC 5353/4 filament galaxies show infall
toward the NGC 5353/4 group, whereas the W-M sheet galaxies do not show hints
of gravitational influence from the Virgo cluster. The filamentary structures
identified can now be used to better understand the generic role of filaments
in the build-up of galaxy clusters at z~~0.Comment: 8 pages, 4 figures, accepted for publication in Ap
The discovery of blue-cored dwarf early-type galaxies in isolated environments
The presence of blue-cored dwarf early-type galaxies (dE(bc)s) in
high-density environments supports the scenario of the transformation of
infalling late-type galaxies into quiescent dwarf early-type galaxies by
environmental effects. While low-density environments lacking environmental
processes could not be relevant to the formation of dE(bc)s, we discovered a
large sample of rare dE(bc)s in isolated environments at z < 0.01 using the
NASA-Sloan Atlas catalog. Thirty-two isolated dE(bc)s were identified by visual
inspection of the Sloan Digital Sky Survey images and g - r color profiles. We
found that (1) isolated dE(bc)s exhibit similar structural parameters to
dE(bc)s in the Virgo cluster; (2) based on the ultraviolet-r color-magnitude
relation, color gradients, and optical emission lines of dE(bc)s, isolated
dE(bc)s show more vigorous, centrally concentrated SF compared to their
counterparts in the Virgo cluster; (3) at a given stellar mass, isolated
dE(bc)s tend to have a larger fraction of gas mass than their Virgo
counterparts. We discuss a scenario of episodic SF sustained by gas accretion,
suggested by Sanchez Almeida et al., in which the star-bursting blue compact
dwarf galaxy (BCD)-quiescent BCD (QBCD) cycle can be repeated during the Hubble
time. We suggest that, in this cadence, isolated dE(bc)s might be QBCDs at pre-
or post-BCD stages. Our results imply that dE(bc)s comprise a mixture of
objects with two types of origins, nature or nurture, depending on their
environment.Comment: 8 pages, 5 figures, accepted for publication in Astrophysical Journa
Nutrigenomic Functions of PPARs in Obesogenic Environments
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors that mediate the effects of several nutrients or drugs through transcriptional regulation of their target genes in obesogenic environments.This review consists of three parts. First, we summarize current knowledge regarding the role of PPARs in governing the development of white and brown/beige adipocytes from uncommitted progenitor cells. Next, we discuss the interactions of dietary bioactive molecules, such as fatty acids and phytochemicals, with PPARs for the modulation of PPAR-dependent transcriptional activities and metabolic consequences. Lastly, the effects of PPAR polymorphism on obesity and metabolic outcomes are discussed. In this review, we aim to highlight the critical role of PPARs in the modulation of adiposity and subsequent metabolic adaptation in response to dietary challenges and genetic modifications. Understanding the changes in obesogenic environments as a consequence of PPARs/nutrient interactions may help expand the field of individualized nutrition to prevent obesity and obesity-associated metabolic comorbidities
- …