We apply Gaussian processes and Hubble function data in f(T) cosmology to reconstruct for the first time the f(T) form in a model-independent way. In particular, using H(z) data sets coming from ...cosmic chronometers as well as from the method of radial baryon acoustic oscillations, alongside the latest released local value of H0 = 73.52 1.62 km s−1 Mpc−1, we reconstruct H(z) and its derivatives, resulting eventually in a reconstructed region for f(T), without any assumption. Although the cosmological constant lies in the central part of the reconstructed region, the obtained mean curve follows a quadratic function. Inspired by this we propose a new f(T) parameterization, i.e., f(T) = −2Λ + T2, with the sole free parameter that quantifies the deviation from ΛCDM cosmology. Additionally, we confront three viable one-parameter f(T) models from the literature, which are the power-law, the square-root exponential, and the exponential models, with the reconstructed f(T) region, and then we extract significantly improved constraints for their model parameters, comparing to the constraints that arise from the usual observational analysis. Finally, we argue that since we are using the direct Hubble measurements and the local value for H0 in our analysis, the H0 tension can be efficiently alleviated with the above reconstruction of f(T).
From recent observational data two significant directions have been made in the field of theoretical cosmology recently. First, we are now able to make use of present observations, such as the Planck ...and BICEP2 data, to examine theoretical predictions from the standard inflationary ACDM which were made decades of years ago. Second, we can search for new cosmological signatures as a way to explore physics beyond the standard cosmic paradigm. In particular, a subset of early universe models admit a nonsingular bouncing solution that attempts to address the issue of the big bang singularity. These models have achieved a series of considerable developments in recent years, in particular in their perturbative frameworks, which made brand-new predictions of cosmological signatures that could be visible in current and forthcoming observations. Herein we present two representative paradigms of early universe physics. The first is the reputed new matter （or matter-ekpyrotic） bounce scenario in which the universe starts with a matter-dominated contraction phase and transitions into an ekpyrotic phase. In the setting of this paradigm, we have proposed some possible mechanisms of generating a red tilt for primordial curvature perturbations and confront the general predictions with recent cosmological observations. The second is the matter-bounce inflation scenario which can be viewed as an extension of inflationary cosmology with a matter contraction before inflation. We present a class of possible model constructions and review the implications on the current CMB experiments. Lastly a review of significant achievements of these paradigms beyond the inflationary ACDM model is made, which is expected to shed new light on the future direction of observational cosmology.
Colloidal noble metal nanoparticles (NPs) are composed of metal cores and organic or inorganic ligand shells. These NPs support size‐ and shape‐dependent plasmonic resonances. They can be assembled ...from dispersions into artificial metamolecules which have collective plasmonic resonances originating from coupled bright and dark optical electric and magnetic modes that form depending on the size and shape of the constituent NPs and their number, arrangement, and interparticle distance. NPs can also be assembled into extended 2D and 3D metamaterials that are glassy thin films or ordered thin films or crystals, also known as superlattices and supercrystals. The metamaterials have tunable optical properties that depend on the size, shape, and composition of the NPs, and on the number of NP layers and their interparticle distance. Interestingly, strong light‐matter interactions in superlattices form plasmon polaritons. Tunable interparticle distances allow designer materials with dielectric functions tailorable from that characteristic of an insulator to that of a metal, and serve as strong optical absorbers or scatterers, respectively. In combination with lithography techniques, these extended assemblies can be patterned to create subwavelength NP superstructures and form large‐area 2D and 3D metamaterials that manipulate the amplitude, phase, and polarization of transmitted or reflected light.
Noble metal nanoparticles (NPs) serve as building blocks in the assembly of artificial metamolecules and large‐area metamaterials. These metastructures have exotic optical properties that depend on the NP number, arrangement, and interparticle spacing, and on the geometry of their patterned 2D and 3D superstructures. Their strong light‐matter interactions are harnessed to manipulate the amplitude, phase, and polarization of light.
Abstract
N6-methyladenosine (m
6
A) is one of the most common RNA modifications in eukaryotes, mainly in messenger RNA (mRNA). Increasing evidence shows that m
6
A methylation modification acts an ...essential role in various physiological and pathological bioprocesses. Noncoding RNAs (ncRNAs), including miRNAs, lncRNAs and circRNAs, are known to participate in regulating cell differentiation, angiogenesis, immune response, inflammatory response and carcinogenesis. m
6
A regulators, such as METTL3, ALKBH5 and IGF2BP1 have been reported to execute a m
6
A-dependent modification of ncRNAs involved in carcinogenesis. Meanwhile, ncRNAs can target or modulate m
6
A regulators to influence cancer development. In this review, we provide an insight into the interplay between m
6
A modification and ncRNAs in cancer.
In our previous work, the concept of critical region in a generalized Aubry–André model (Ganeshan–Pixley–Das Sarma’s model) has been established. In this work, we find that the critical region can be ...realized in a one-dimensional flat band lattice with a quasi-periodic potential. It is found that the above flat band lattice model can be reduced to an effective Ganeshan–Pixley–Das Sarma’s model. Depending on various parameter ranges, the effective quasi-periodic potential may be bounded or unbounded. In these two cases, the Lyapunov exponent, mobility edge, and critical indices of localized length are obtained exactly. In this flat band model, the localized-extended, localized-critical and critical-extended transitions can coexist. Furthermore, we find that near the transitions between the bound and unbounded cases, the derivative of Lyapunov exponent of localized states with respect to energy is discontinuous. At the end, the localized states in bounded and unbounded cases can be distinguished from each other by Avila’s acceleration.
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