Abstract
The dispersion measure (DM)–redshift relation of fast radio bursts (FRBs) has been proposed as a potential new tool for probing the intergalactic medium (IGM) and for studying cosmology. ...However, poor knowledge of the baryon fraction in the IGM (
f
IGM
) and its degeneracy with cosmological parameters impose restrictions on the cosmological applications of FRBs. Furthermore, DMs contributed by the IGM (DM
IGM
) and host galaxy (DM
host
), important cosmological quantities, cannot be exactly extracted from observations, which would bring uncontrolled systematic uncertainties in FRB cosmology. In this work, we use 17 localized FRBs to constrain
f
IGM
and its possible redshift evolution. Other cosmological probes such as type Ia supernovae, baryon acoustic oscillations, and cosmic microwave background radiation are combined to break parameter degeneracy. Taking into account the probability distributions of DM
IGM
and DM
host
derived from the IllustrisTNG simulation, we obtain a robust measurement of
f
IGM
= 0.927 ± 0.075, representing a precision of 8.0%. We find that there is no strong evidence for the redshift dependence of
f
IGM
at the current observational data level. The rapid progress in localizing FRBs will significantly improve the constraints on
f
IGM
.
In this paper, we propose an improved model-independent method to constrain the cosmic curvature by combining the most recent Hubble parameter H(z) and supernovae Ia (SNe Ia) data. Based on the H(z) ...data, we first use the model-independent smoothing technique, Gaussian processes, to construct a distance modulus H(z), which is susceptible to the cosmic curvature parameter k. In contrary to previous studies, the light-curve-fitting parameters, which account for the distance estimation of SN ( SN(z)), are set free to investigate whether k has a dependence on them. By comparing H(z) to SN(z), we put limits on k. Our results confirm that k is independent of the SN light-curve parameters. Moreover, we show that the measured k is in good agreement with zero cosmic curvature, implying that there is no significant deviation from a flat universe at the current observational data level. We also test the influence of different H(z) samples and different Hubble constant H0 values, finding that different H(z) samples do not have a significant impact on the constraints. However, different H0 priors can affect the constraints of k to some degree. The prior of H0 = 73.24 1.74 km s−1 Mpc−1 gives a value of k, a little bit above the 1 confidence level away from 0, but H0 = 69.6 0.7 km s−1 Mpc−1 gives it below 1 .
Dielectric polyimides (PIs) are ubiquitous as insulation in electrical power systems and electronic devices. Generally, dynamic polyimide is required to solve irreversible failure processes of ...electrical or mechanical damage, for example, under high temperature, pressure, and field strength. The challenge lies in the design of the molecular structure of rigid polyimide to achieve dynamic reversibility. Herein, a low‐molecular‐weight polyimide gene unit is designed to crosslink with polyimide ligase to prepare the smart film. Interestingly, due to the variability of gene unit and ligase combinations, the polyimide films combining hardness with softness are designed into three forms via a “Mimosa‐like” bionic strategy to adapt to different application scenarios. Meanwhile, the films have good degradation efficiency, excellent recyclability, and can be self‐healable, which makes them reuse. Clearly, the films can be used in the preparation of ultrafast sensors with a response time ≈0.15 s and the application of corona‐resistant films with 100% recovery. Furthermore, the construction of polyimide and carbon‐fiber‐reinforced composites (CFRCs) has been verified to apply to the worse environment. Nicely, the composites have the property of multiple cycles and the non‐destructive recycle rate of carbon fiber (CF) is as high as 100%. The design idea of preparing high‐strength dynamic polyimide by crosslinking simple polyimide gene unit with ligase could provide a good foundation and a clear case for the sustainable development of electrical and electronic polyimides, from the perspective of Mimosa bionics.
A dynamic polyimide (PI) film, which can transform among three molecular structures, is designed by imitating the behavior of the Mimosa plant. The PI film is a super‐corona‐resistant film, a matrix of high‐sensitivity humidity sensor and carbon‐fiber‐reinforced composites due to its excellent capabilities of degradation, self‐healable ability, and recyclability.
Malayan pangolin SARS-CoV-2-related coronavirus (SARSr-CoV-2) is closely related to SARS-CoV-2. However, little is known about its pathogenicity in pangolins. Using CT scans we show that SARSr-CoV-2 ...positive Malayan pangolins are characterized by bilateral ground-glass opacities in lungs in a similar manner to COVID-19 patients. Histological examination and blood gas tests are indicative of dyspnea. SARSr-CoV-2 infected multiple organs in pangolins, with the lungs the major target, and histological expression data revealed that ACE2 and TMPRSS2 were co-expressed with viral RNA. Transcriptome analysis indicated that virus-positive pangolins were likely to have inadequate interferon responses, with relative greater cytokine and chemokine activity in the lung and spleen. Notably, both viral RNA and viral proteins were detected in three pangolin fetuses, providing initial evidence for vertical virus transmission. In sum, our study outlines the biological framework of SARSr-CoV-2 in pangolins, revealing striking similarities to COVID-19 in humans.
Nitrogen‐doped polycyclic aromatic hydrocarbons (aza‐PAHs) have found broad applications in material sciences. Herein, a modular electrochemical synthesis of aza‐PAHs was developed via a ...rhodium‐catalyzed cascade C−H activation and alkyne annulation. A multifunctional O‐methylamidoxime enabled the high chemo‐ and regioselectivity. The isolation of two key rhodacyclic intermediates made it possible to delineate the exact order of three C−H activation steps. In addition, the metalla‐electrocatalyzed multiple C−H transformation is characterized by unique functional group tolerance, including highly reactive iodo and azido groups.
Electrochemical access to aza‐polycyclic aromatic hydrocarbons (aza‐PAHs) was achieved via rhoda‐electrocatalyzed domino C−H functionalization. A multifunctional O‐methylamidoxime facilitates the high chemo‐ and regioselectivity. The obtained aza‐PAHs and their derivatives have potential applications in catalysis, optoelectronics, and energy storage.
Low‐dimensional lead halide perovskite materials recently have drawn much attention owing to the intriguing broadband emissions; however, the toxicity of lead will hinder their future development. ...Now, a lead‐free (C4H14N2)2In2Br10 single crystal with a unique zero‐dimensional (0D) structure constituted by InBr63− octahedral and InBr4− tetrahedral units is described. The single crystal exhibits broadband photoluminescence (PL) that spans almost the whole visible spectrum with a lifetime of 3.2 μs. Computational and experimental studies unveil that an excited‐state structural distortion in InBr63− octahedral units enables the formation of intrinsic self‐trapped excitons (STEs) and thus contributing the broad emission. Furthermore, femtosecond transient absorption (fs‐TA) measurement reveals that the ultrafast STEs formation together with an efficient intersystem crossing has made a significant contribution to the long‐lived and broad STE‐based emission behavior.
A lead‐free indium‐based (C4H14N2)2In2Br10 single crystal was synthesized and characterized; it has a unique 0D crystal structure. An intrinsic self‐trapped exciton‐based ultra‐broad photoluminescence has been observed as a result of an excited‐state structural distortion in InBr63− octahedrons.
Abstract
We use the dispersion measure (DM) and redshift measurements of 24 localized fast radio bursts (FRBs) to compare cosmological models and investigate the Hubble tension. Setting a flat prior ...on the DM contribution from the Milky Way’s halo,
DM
halo
MW
∈
5
,
80
pc
cm
−
3
, the best fit for flat ΛCDM is obtained with a Hubble constant
H
0
=
95.8
−
9.2
+
7.8
km
s
−
1
Mpc
−
1
and a median matter density Ω
m
≈ 0.66. The best fit for the
R
h
=
ct
universe is realized with
H
0
=
94.2
−
6.2
+
5.6
km
s
−
1
Mpc
−
1
. We emphasize that the
H
0
measurement depends sensitively on the
DM
halo
MW
prior. Since flat ΛCDM has one more free parameter,
R
h
=
ct
is favored by the Bayesian Information Criterion (BIC) with a likelihood of ∼73% versus ∼27%. Through simulations, we find that if the real cosmology is ΛCDM, a sample of ∼1150 FRBs in the redshift range 0 <
z
< 3 would be sufficient to rule out
R
h
=
ct
at a 3
σ
confidence level, while ∼550 FRBs would be necessary to rule out ΛCDM if the real cosmology is instead
R
h
=
ct
. The required sample sizes are different, reflecting the fact that the BIC imposes a severe penalty on the model with more free parameters. We further adopt a straightforward method of deriving an upper limit to
H
0
, without needing to consider the poorly known probability distribution of the DM contributed by the host galaxy. The theoretical DM contribution from the intergalactic medium (DM
IGM
) at any
z
is proportional to
H
0
. Thus, requiring the extragalactic DM
ext
to be larger than DM
IGM
delimits
H
0
to the upside. Assuming flat ΛCDM, we have
H
0
< 89.0 km s
−1
Mpc
−1
at a 95% confidence level.
Classifier fusion is an efficient strategy to improve the classification performance for the complex pattern recognition problem. In practice, the multiple classifiers to combine can have different ...reliabilities and the proper reliability evaluation plays an important role in the fusion process for getting the best classification performance. We propose a new method for classifier fusion with contextual reliability evaluation (CF-CRE) based on inner reliability and relative reliability concepts. The inner reliability, represented by a matrix, characterizes the probability of the object belonging to one class when it is classified to another class. The elements of this matrix are estimated from the <inline-formula> <tex-math notation="LaTeX">K </tex-math></inline-formula>-nearest neighbors of the object. A cautious discounting rule is developed under belief functions framework to revise the classification result according to the inner reliability. The relative reliability is evaluated based on a new incompatibility measure which allows to reduce the level of conflict between the classifiers by applying the classical evidence discounting rule to each classifier before their combination. The inner reliability and relative reliability capture different aspects of the classification reliability. The discounted classification results are combined with Dempster-Shafer's rule for the final class decision making support. The performance of CF-CRE have been evaluated and compared with those of main classical fusion methods using real data sets. The experimental results show that CF-CRE can produce substantially higher accuracy than other fusion methods in general. Moreover, CF-CRE is robust to the changes of the number of nearest neighbors chosen for estimating the reliability matrix, which is appealing for the applications.
The emerging role of miR‐375 in cancer Yan, Jun‐Wei; Lin, Ju‐Sheng; He, Xing‐Xing
International journal of cancer,
01 September 2014, Volume:
135, Issue:
5
Journal Article
Peer reviewed
Open access
MicroRNAs (miRNAs) are evolutionarily conserved, small noncoding RNAs that are believed to play fundamental roles in various biological processes through regulation of gene expression at the level of ...posttranscription. MiR‐375 was first identified as a pancreatic islet‐specific miRNA regulating insulin secretion. However, further study revealed that miR‐375 is a multifunctional miRNA participating in pancreatic islet development, glucose homeostasis, mucosal immunity, lung surfactant secretion and more importantly, tumorigenesis. Recently, miR‐375 has been found significantly downregulated in multiple types of cancer, and suppresses core hallmarks of cancer by targeting several important oncogenes like AEG‐1, YAP1, IGF1R and PDK1. The alteration of miR‐375 in cancer is caused by a variety of mechanisms, including the dysregulation of transcription factors, aberrant promoter methylation and so on. Reduced expression of miR‐375 in tissue or circulation may indicate the presence of neoplasia as well as a poor prognosis of many malignant cancers. Moreover, miR‐375 stands for a promising direction for developing targeted therapies due to its capacity to inhibit tumor cell growth in vitro and in vivo. Here, we summarize the present understanding of the tumor suppressive role of miR‐375 in cancer progression; the mechanisms underlying the dysregulation of miR‐375; the potential use of miR‐375 in prognosis and diagnosis and the therapeutic prospects of miR‐375 in cancer.
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