99 research outputs found
Star Formation and Chemical Enrichment in Protoclusters
We examine star formation and chemical enrichment in protoclusters (PCs)
using cosmological zoom-in hydrodynamic simulations. We find that the total
star formation rate (SFR) in all PC (M) reaches
at , equivalent to the observed
PCs. The SFR in the Core region accounts for about of the total star
formation in the PC at , suggesting the importance of the outer
regions to reveal the evolution of galaxy clusters. We find that the total SFR
of PC is dominated by galaxies with
, while more massive
galaxies dominate the SFR in the Core. For the chemical abundance evolution, we
find that the higher-density region has a higher metallicity and faster
evolution. We show that the [O/Fe] vs. [Fe/H] relation turns down in the Core
at due to the enrichment of Fe by Type Ia supernovae. We find no
environmental effects for the mass--metallicity relations (MZR) or (N/O)
vs. (O/H) for galaxies. We find that the chemical enrichment in galaxy
clusters proceeds faster in the high redshift Universe (). Our work will
benefit future tomographic observations, particularly using PCs as unique
probes of accelerated structure formation and evolution in high-density regions
of the universe.Comment: 19 pages, 18 figures, 2 tables, 2 appendices, Accepted for
publication in MNRA
Detection Prospects for Majorana Fermion WIMPless Dark Matter
We consider both velocity-dependent and velocity-independent contributions to
spin-dependent (SD) and spin-independent (SI) nuclear scattering (including
one-loop corrections) of WIMPless dark matter, in the case where the dark
matter candidate is a Majorana fermion. We find that spin-independent
scattering arises only from the mixing of exotic squarks, or from
velocity-dependent terms. Nevertheless (and contrary to the case of MSSM
neutralino WIMPs), we find a class of models which cannot be detected through
SI scattering, but can be detected at IceCube/DeepCore through SD scattering.
We study the detection prospects for both SI and SD detection strategies for a
large range of Majorana fermion WIMPless model parameters.Comment: 14 pages, 3 figures. v2: updated to match published versio
Denoising using deep-learning-based reconstruction for whole-heart coronary MRA with sub-millimeter isotropic resolution at 3 T: a volunteer study
PURPOSEThe aim of this study was to assess the usefulness of denoising deep-learning-based reconstruction (dDLR) to improve image quality and vessel delineation in noncontrast 3-T wholeheart coronary magnetic resonance angiography (WHCMRA) with sub-millimeter isotropic resolution (Sub-mm) compared with a standard resolution without dDLR (Standard).METHODSFor 10 healthy volunteers, we acquired the WHCMRA with Sub-mm with and without dDLR and Standard to quantify signal- (SNR) and contrast-to-noise ratio (CNR) and vessel edge signal response (VESR) in all the 3 image types. Two independent readers subjectively graded vessel sharpness and signal homogeneity of 8 coronary segments in each patient. We used Kruskal– Wallis test with Bonferroni correction to compare SNR, CNR, VESR, and the subjective evaluation scores among the 3 image types and weighted kappa test to evaluate inter-reader agreement on the scores.RESULTSSNR was significantly higher with Sub-mm with dDLR (P .05); the subjective signal homogeneity was significantly improved from Sub-mm without dDLR to Standard to Sub-mm with dDLR (P < .001). The inter-reader agreement was excellent (kappa=0.84).CONCLUSIONApplication of dDLR is useful for improving image quality and vessel delineation in the WHCMRA with Sub-mm compared with Standard
Microscopic distribution of alkaloids in freeze-fixed stems of Phellodendron amurense
IntroductionPhellodendron amurense Rupr. contains rich alkaloids, which have been extensively applied in clinical treatments for their various biological activities. However, detailed microscopic distribution and roles of such alkaloids in P. amurense stem still need to be clarified.MethodsIn this study, the distribution of eight alkaloids in the transverse surface of freeze-fixed P. amurense stems in fall and summer has been visualized by cryo-time-of-flight secondary ion mass spectrometry and scanning electron microscopy (cryo-TOF-SIMS/SEM), which was found in living tissues with relative contents of different alkaloids varying with the position. In addition, the contents of these alkaloids quantified by high-performance liquid chromatography (HPLC) analysis suggested the seasonal variation from fall to the following summer.Results and discussionDistribution of eight alkaloids in the freeze-fixed stems of P. amurense from fall and summer seasons has been visualized and assigned into specific living tissues, with relative contents varying in different positions with seasons, which suggested their possible roles in the physiological processes of the plant itself or plant responding to changes in the surrounding conditions.ConclusionThis study provided a significant basis for further discussion of the genes or enzymes involved in these processes, which will contribute to investigating biosynthetic pathways and specific in planta roles of alkaloids
- …