Ultra-compact X-ray binaries (UCXBs) are low-mass X-ray binaries with ultra-short orbital periods (usually less than 1 hr) and hydrogen-poor donor stars, which are proposed to be potential Laser ...Interferometer Space Antenna (LISA) sources. In this work, we first employ the Modules for Experiments in Stellar Astrophysics code to examine the parameter space of the progenitors of UCXBs that LISA will detect. Our simulations indicate that the initial binaries with a neutron star and a companion star, in an orbit of initial orbital period smaller than the bifurcation period, could evolve into UCXBs, some of which will emit gravitational wave signals that can be detectable by LISA. However, the initial orbital periods of the binaries that will evolve into UCXB-LISA sources in a distance of 10 kpc are located in a very narrow range, i.e., the formation of these LISA source requires an extreme fine-tuning of initial parameter. According to the characteristic strains and the derived maximum detectable distances, four sources among eight UCXBs with the observed distances are expected to be detected by LISA. Based on the parameter space given by the detailed binary evolution models and the rapid binary star evolution code, the birthrate of UCXBs appearing as LISA sources in the Galaxy is estimated to be . Considering the contribution of UCXBs in globular clusters, the number of UCXB-LISA sources can reach 240-320. Although the formation condition is severe, the detectability of UCXBs by LISA is still significant because it provides an opportunity to pursue full multi-messenger investigations.
The scientific aim of the space gravitational-wave (GW) detector Laser Interferometer Space Antenna (LISA) that was scheduled to launch in the early 2030s is to detect the low-frequency GW signals in ...the Galaxy. Its main candidate GW sources are compact binaries of white dwarfs and neutron stars. In this work, we examine whether compact intermediate-mass black hole (IMBH) X-ray binaries could be potential LISA sources. Our simulations indicate that an IMBH binary with a 1000 M IMBH and a 3 M donor star in an initial orbital period near the so-called bifurcation period of 0.77 day could evolve into an ultra-compact X-ray binary, which will emit GW signals with a maximum frequency of 2.5 mHz. According to the evolutionary tracks of characteristic strain, IMBH X-ray binaries with the initial donor-star masses of 1-3 M and the initial orbital periods slightly less than the bifurcation periods will be detectable by the LISA in a distance of 15 kpc. Assuming each of 60 Galactic globular clusters hosts a 1000 M IMBH, the maximum number of compact IMBH X-ray binaries that LISA will detect in the Galaxy should be less than ten. Therefore, the detectability of compact IMBH X-ray binaries by the LISA is not optimistic.
In 2010, a panel of Chinese pathologists reported the first expert consensus for the pathological diagnosis of primary liver cancers to address the many contradictions and inconsistencies in the ...pathological characteristics and diagnostic criteria for PLC. Since then considerable clinicopathological studies have been conducted globally, prompting us to update the practice guidelines for the pathological diagnosis of PLC. In April 18, 2014, a Guideline Committee consisting of 40 specialists from seven Chinese Societies(including Chinese Society of Liver Cancer, Chinese Anti-Cancer Association; Liver Cancer Study Group, Chinese Society of Hepatology, Chinese Medical Association; Chinese Society of Pathology, Chinese Anti-Cancer Association; Digestive Disease Group, Chinese Society of Pathology, Chinese Medical Association; Chinese Society of Surgery, Chinese Medical Association; Chinese Society of Clinical Oncology, Chinese Anti-Cancer Association; Pathological Group of Hepatobiliary Tumor and Liver Transplantation, Chinese Society of Pathology, Chinese Medical Association) was created for the formulation of the first guidelines for the standardization of the pathological diagnosis of PLC, mainly focusing on the following topics: gross specimen sampling, concepts and diagnostic criteria of small hepatocellular carcinoma(SHCC), microvascular invasion(MVI), satellite nodules,and immunohistochemical and molecular diagnosis. The present updated guidelines are reflective of current clinicopathological studies, and include a novel 7-point baseline sampling protocol, which stipulate that at least four tissue specimens should be sampled at the junction of the tumor and adjacent liver tissues in a 1:1 ratio at the 12, 3, 6 and 9 o’clock reference positions. For the purposes of molecular pathological examination, at least one specimen should be sampled at the intratumoral zone, but more specimens should be sampled for tumors harboring different textures or colors. Specimens should be sampled at both adjacent and distant peritumoral liver tissues or the tumor margin in order to observe MVI, satellite nodules and dysplastic foci/nodules distributed throughout the background liver tissues. Complete sampling of whole SHCC ≤ 3 cm should be performed to assess its biological behavior, and in clinical practice, therapeutic borders should be also preserved, even in SHCC. The diagnostic criteria of MVI and satellite nodules, immunohistochemical panels, as well as molecular diagnostic principles, such as clonal typing, for recurrent HCC and multinodule HCC were also proposed and recommended. The standardized process of pathological examination is aimed at ensuring the accuracy of pathological PLC diagnoses as well as providing a valuable frame of reference for the clinical assessment of tumor invasive potential, the risk of postoperative recurrence, long-term survival, and the development of individualized treatment regimens. The updated guidelines could ensure the accuracy of pathological diagnoses of PLC, and provide a valuable frame of reference for its clinical assessment.
Binary millisecond pulsars (MSPs) are detached systems consisting of a MSP and a He white dwarf. If the initial orbital periods of binary MSPs are shorter than 0.3 day, they would evolve toward ...ultracompact binary pulsars due to the rapid orbital shrinkage by the gravitational wave (GW) radiation. During the orbital decay, the MSP with an ellipticity would spin down due to GW radiation and magnetic dipole radiation. Our calculations indicate that the angular momentum loss is dominated by the GW radiation when the ellipticities of the neutron stars (NSs) are in the range of ( 1 – 50 ) × 10−7, and the frequencies of high-frequency GW signals from the rotating NSs are 10–100 Hz when the binary pulsars can be visible as low-frequency GW sources. These high-frequency GW signals are possible to be detected by aLIGO and the third-generation GW detectors such as Einstein Telescope, depending on the frequencies and the distances. Therefore, ultracompact binary pulsars have an opportunity to become intriguing dual-line GW sources. By detecting low-frequency GW signals, the NS mass can be accurately derived. A dual-line detection of two band GW signals could provide a constraint on the moment of inertia and the ellipticity of the NS. Thus dual-line GW sources can be potentially applied to constrain the equation of state of NSs.
Abstract
In the Galaxy, close binaries with compact objects are important low-frequency gravitational wave (GW) sources. As potential low-frequency GW sources, neutron star/white dwarf (WD) ...ultracompact X-ray binaries (UCXBs) have been investigated extensively. Using the Modules for Experiments in Stellar Astrophysics code, we systematically explored the evolution of black hole (BH)-main-sequence star (MS) binaries to determine whether their descendants can be detected by space-borne GW detectors. Our simulations showed that BH-MS binaries with an initial orbital period less than the bifurcation period can evolve into BH UCXBs that can be detected by LISA. Such an evolutionary channel would form compact mass-transferring BH-WD systems rather than detached BH-WD systems. The calculated X-ray luminosities of BH UCXBs that can be detected by LISA at a distance
d
= 1 kpc are ∼10
33
–10
35
erg s
−1
(∼10
34
–10
35
erg s
−1
for
d
= 10 kpc); hence, it is possible to detect their electromagnetic counterparts. It is worth emphasizing that only some BH-MS systems with an initial orbital period very close to the bifurcation period can evolve toward low-frequency GW sources whose chirp masses can be measured. The maximum GW frequency of BH UCXBs forming via the BH-MS pathway is about 3 mHz, which is smaller than the minimum GW frequency (6.4 mHz) of mass-transferring BH-WDs originating from a dynamic process. Furthermore, we obtain an initial parameter space (donor-star masses and orbital periods) of progenitors of BH UCXB-GW sources, which can be applied to future population synthesis simulations. By a rough estimation, we predict that LISA would only be able to detect a few BH UCXB-GW sources formed by the BH-MS channel.
A spinning neutron star (NS) that is asymmetric with respect to its spin axis can emit continuous gravitational wave (GW) signals. The spin frequencies and their distribution of radio millisecond ...pulsars (MSPs) and accreting MSPs provide some evidences of GW radiation, and MSPs are ideal probes detecting high frequency GW signals. It is generally thought that MSPs originate from the recycled process, in which the NS accretes the material and angular momentum from the donor star. The accreted matter would be confined at the polar cap zone by an equatorial belt of compressed magnetic field fixed in the deep crust of the NS, and yields "magnetic mountain." Based on an assumption that the spin-down rates of three transitional MSPs including PSR J 1023 + 0038 are the combinational contribution of the accretion torque, the propeller torque, and the GW radiation torque, in this work we attempt to constrain the ellipticities of MSPs with observed spin-down rates. Assuming some canonical parameters of NSs, the ellipticities of three transitional MSPs and ten redbacks are estimated to be ε = (0.9 − 23.4) × 10−9. The electrical resistivities of three transitional MSPs are also derived to be in the range η = (1.2 − 15.3) × 10−31 s, which display an ideal power law relation with the accretion rate. The characteristic strains (hc = (0.6 − 2.5 ) × 10−27) of GW signals emitting by these sources are obviously beyond the sensitivity scope of the aLIGO. We expect that the third-generation GW detectors like the Einstein Telescope can seize the GW signals from these sources in the future.
Abstract Recently, two ultralong-period radio transients, GLEAM-X J162759.5-523504.3 (J1627) and GPM J1839-10 (J1839), were discovered with spin periods longer than 1000 s. The origin of these two ...ultralong-period radio transients is intriguing in understanding the spin evolution of neutron stars (NSs). In this work, we examine whether the interaction between strong magnetized NSs and fallback disks can spin NSs down to the observed ultralong period. Our simulations found that the magnetar + fallback disk model can account for the observed period, period derivative, and X-ray luminosity of J1627 in the quasi-spin-equilibrium stage. To evolve to the current state of J1627, the initial mass-accretion rate of the fallback disk and the magnetic field of the NS are in the range of (1.1–30) × 10 24 g s −1 and (2–5) × 10 14 G, respectively. In the active lifetime of the fallback disk, it is impossible for J1839 to achieve the observed upper limit of the period derivative. Therefore, we propose that J1839 may be in the second ejector phase after the fallback disk becomes inactive. Those NSs with a magnetic field of (2–6) × 10 14 G and a fallback disk with an initial mass-accretion rate of ∼10 24 –10 26 g s −1 are possible progenitors of J1839.
HD 49798/RX J0648.0C4418 is a peculiar binary including a hot subdwarf of O spectral type and a compact companion in a 1.55 day orbit. Based on the steady spin period derivative
Ṗ
= (−2.17 ± 0.01) × ...10
−15
s s
−1
, the compact object was thought to be a contracting young white dwarf (WD). However, the X-ray luminosity produced by the wind accretion of the massive WD is one order of magnitude smaller than the observed value. In this work, we propose an alternative model to account for the observed X-ray luminosity. If the WD were surrounded by a debris disk, the accretion from the debris disk could produce the observed X-ray luminosity and X-ray pulses. Based on the time-varying accretion rate model, the current mass of the debris disk is constrained to 3.9 × 10
−6
M
⊙
. The accretion torque exerted by such a debris disk can only influence the spin evolution of the WD in the early stages, and its affect is obviously smaller than that caused by the contraction of the WD in the current stage. According to accretion theory, the magnetic field of the WD is constrained to ∼(0.7−7) × 10
4
G. The calculated conventional polar cap radius of the WD is larger than the observed emitting-zone radius, which probably originates from the existence of strong and small-scale local magnetic field in the polar cap surface. We expect that further multiband observations of this source could help us to confirm or rule out the existence of a debris disk.
Magnetic relaxation switching (MRS) sensors have shown great potential in food safety monitoring due to their high signal‐to‐noise ratio and simplicity, but they often suffer from insufficient ...sensitivity and stability due to the lack of excellent magnetic nanoprobes. Herein, dumbbell‐like Au–Fe3O4 nanoparticles are designed as magnetic nanoprobes for developing an aflatoxin B1‐MRS immunosensor. The Fe3O4 portion in the Au–Fe3O4 nanoparticles functions as the magnetic probe to provide transverse relaxation signals, while the Au segments serve as a bridge to grow Ag shell and assemble the Au–Fe3O4 nanoparticles, thus modulating transverse relaxation time of surrounding water molecular. The formation of Ag@Au–Fe3O4 is triggered by hydrogen peroxide. After degraded by horseradish peroxidase, hydrogen peroxide reduces Ag+ to Ag nanoparticles which assemble dispersed Au–Fe3O4 to aggregated Ag@Au–Fe3O4, thus dramatically improving the sensitivity of traditional MRS sensor. Combined with competitive immunoreaction, this Ag@Au–Fe3O4–MRS immunosensor can detect aflatoxin B1 with a high sensitivity (3.81 pg mL−1), which improved about 21 folds and 9 folds than those of enzyme‐linked immunosorbent assay and high‐performance liquid chromatography (HPLC), respectively. The good consistency with HPLC in real samples detection indicates the good accuracy of this immunosensor. This Ag@Au–Fe3O4–MRS immunosensor offers an attractive tool for detection of harmful substances.
Dumbbell‐like Au–Fe3O4 nanoparticles are designed as magnetic nanoprobes to participate in the hydrogen peroxide‐mediated assembly of Ag@Au–Fe3O4 for magnetic biosensing. Compared with enzyme‐linked immunosorbent assay, this Ag@Au–Fe3O4–MRS immunosensor not only improves the sensitivity (21‐fold enhancement) but also enhances the stability in the detection of aflatoxin B1, which greatly broaden the applications of magnetic relaxation switching biosensors.
Recent interest in the control of bone metabolism has focused on a specialized subset of CD31
endomucin
vessels, which are reported to couple angiogenesis with osteogenesis. However, the underlying ...mechanisms that link these processes together remain largely undefined. Here we show that the zinc-finger transcription factor ZEB1 is predominantly expressed in CD31
endomucin
endothelium in human and mouse bone. Endothelial cell-specific deletion of ZEB1 in mice impairs CD31
endomucin
vessel formation in the bone, resulting in reduced osteogenesis. Mechanistically, ZEB1 deletion reduces histone acetylation on Dll4 and Notch1 promoters, thereby epigenetically suppressing Notch signaling, a critical pathway that controls bone angiogenesis and osteogenesis. ZEB1 expression in skeletal endothelium declines in osteoporotic mice and humans. Administration of Zeb1-packaged liposomes in osteoporotic mice restores impaired Notch activity in skeletal endothelium, thereby promoting angiogenesis-dependent osteogenesis and ameliorating bone loss. Pharmacological reversal of the low ZEB1/Notch signaling may exert therapeutic benefit in osteoporotic patients by promoting angiogenesis-dependent bone formation.
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