37 research outputs found
ELM of ELM-WD: An extremely low mass hot donor star discovered in LAMOST survey
The Extremely Low Mass White Dwarfs (ELM WDs) and pre-ELM WDs are helium core
white dwarfs with mass . They are formed in close binaries
and have lost over half of their initial masses via Common Envelope (CE)
ejection or stable Roche Lobe Over Flow (RLOF). Both evolution simulations and
observations show that a lower mass limit for ELM WDs exists at
. Here we report the discovery of an extremely low mass
ELM WD, ID70904216 in LAMOST survey, that may be lower than the ELM WD mass
limit. Based on LAMOST and P200 spectroscopic observations, ID70904216 shows
orbital period 0.219658 days and radial velocity semi-amplitude
, which gives the mass function of 0.73, indicating
the companion is a compact star. The low resolution spectra shows a F type star
with without emission features. The temperature is
consistent with that derived from SED fitting() and multi-color light
curve solution(). The optical light curves, in ZTF g, r and i bands and
Catalina V band, show ellipsoidal variability with amplitudes ,
suggesting that the visible companion is heavily tidal distorted. Combining
with the distance from Gaia survey, the WD code modeling estimates that the
mass of the visible star is , and the mass of
the invisible star is . The radius of the
visible donor is . The inclination angle is constrained
between 60 and 90. The observations indicate the system is
a pre-ELM WD + WD/NS binary system with an extremely low mass hot donor below
the theoretical limit.Comment: 16 pages, 10 figure
Orbital parameters for an ELM white dwarf with a white dwarf companion: LAMOST J033847.06+413424.2
Double white dwarf systems are of great astrophysical importance in the field
of gravitational wave and Type Ia supernova. While the binary fraction of CO
core white dwarf is about a few percents, the extremely low mass white dwarfs
are all thought to be within binary systems. In this work, we report the
orbital solution of a double degenerate system: J033847.06+413424.24, an
extremely low mass He core white dwarf orbiting a CO core white dwarf. With
LAMOST and P200, time domain spectroscopic observations have been made and
spectral atmosphere parameters are estimated to be K and
log dex. Combining Gaia parallax, 3D extinction, and evolution
tracks, we estimate a radius of and a mass of
. With the 37 single exposure spectra, the radial velocities are
measured and the orbital parameters are estimated to be days,
km/s and km/s. The radial velocity based system
ephemeris is also provided. The light curves from several photometric surveys
show no orbital modulation. The orbital solution suggests that the invisible
companion has a minimum mass of about 0.60 and is
for an inclination of , indicating most probably a CO
core white dwarf. The system is expected to merge in about 1 Gyr. With present
period and distance ( pc) it can not irradiate strong enough
gravitational wave for LISA. More double degenerate systems are expected to be
discovered and parameterized as the LAMOST survey goes on.Comment: 12 pages, 11 figure
PRDM12 Is Required for Initiation of the Nociceptive Neuron Lineage during Neurogenesis
Summary: The sensation of pain is essential for the preservation of the functional integrity of the body. However, the key molecular regulators necessary for the initiation of the development of pain-sensing neurons have remained largely unknown. Here, we report that, in mice, inactivation of the transcriptional regulator PRDM12, which is essential for pain perception in humans, results in a complete absence of the nociceptive lineage, while proprioceptive and touch-sensitive neurons remain. Mechanistically, our data reveal that PRDM12 is required for initiation of neurogenesis and activation of a cascade of downstream pro-neuronal transcription factors, including NEUROD1, BRN3A, and ISL1, in the nociceptive lineage while it represses alternative fates other than nociceptors in progenitor cells. Our results thus demonstrate that PRDM12 is necessary for the generation of the entire lineage of pain-initiating neurons. : The sensation of pain, temperature, and itch by neurons of the nociceptive lineage is essential for animal survival. Bartesaghi et al. report that the transcriptional regulator PRDM12 is indispensable in neural crest cells (NCCs) for the initiation of the sensory neuronal differentiation program that generates the entire nociceptive lineage. Keywords: neurogenesis, pain, nociceptive neurons, Prdm12, neural crest cell
Single-cell atlas reveals different immune environments between stable and vulnerable atherosclerotic plaques
IntroductionRegardless of the degree of stenosis, vulnerable plaque is an important cause of ischemic stroke and thrombotic complications. The changes of the immune microenvironment within plaques seem to be an important factor affecting the characteristics of the plaque. However, the differences of immune microenvironment between stable and vulnerable plaques were remained unknown.MethodsIn this study, RNA-sequencing was performed on superficial temporal arteries from 5 traumatic patients and plaques from 3 atherosclerotic patients to preliminary identify the key immune response processes in plaques. Mass cytometry (CyTOF) technology was used to explore differences in immune composition between 9 vulnerable plaques and 12 stable plaques. Finally, immunofluorescence technique was used to validate our findings in the previous analysis.ResultsOur results showed that more CD86+CD68+ M1 pro-inflammatory macrophages were found in vulnerable plaques, while CD4+T memory cells were mainly found in stable plaques. In addition, a CD11c+ subset of CD4+T cells with higher IFN-r secretion was found within the vulnerable plaque. In two subsets of B cells, CD19+CD20-B cells in vulnerable plaques secreted more TNF-a and IL-6, while CD19-CD20+B cells expressed more PD-1 molecules.ConclusionIn conclusion, our study suggested that M1-like macrophages are the major cell subset affecting plaque stability, while functional B cells may also contribute to plaque stability