We consider observational effects of a running effective Planck mass in the scalar-tensor gravity theory. At the background level, an increasing effective Planck mass allows a larger Hubble constant ...H sub(0), which is more compatible with the local direct measurements. At the perturbative level, for cosmic microwave background (CMB) anisotropies, an increasing effective Planck mass (i) suppresses the unlensed CMB power at scriptl< or =30 via the integrated Sachs-Wolfe effect and (ii) enhances CMB lensing power. Both effects slightly relax the tension between the current CMB data from the Planck satellite and the standard LambdaCDM model predictions. However, these impacts on the CMB secondary anisotropies are subdominant, and the overall constraints are driven by the background measurements. Combining CMB data from the Planck satellite and an H sub(0) prior from Riess et al., we find a ~2sigma hint of a positive running of the effective Planck mass. However, the hint goes away when we add other low-redshift observational data including type Ia supernovae, baryon acoustic oscillations, and an estimation of the age of the Universe using the old stars.
The fast industrialization process has led to global challenges in the energy crisis and environmental pollution, which might be solved with clean and renewable energy. Highly efficient ...electrochemical systems for clean‐energy collection require high‐performance electrocatalysts, including Au, Pt, Pd, Ru, etc. Graphene, a single‐layer 2D carbon nanosheet, possesses many intriguing properties, and has attracted tremendous research attention. Specifically, graphene and graphene derivatives have been utilized as templates for the synthesis of various noble‐metal nanocomposites, showing excellent performance in electrocatalytic‐energy‐conversion applications, such as the hydrogen evolution reaction and CO2 reduction. Herein, the recent progress in graphene‐based noble‐metal nanocomposites is summarized, focusing on their synthetic methods and electrocatalytic applications. Furthermore, some personal insights on the challenges and possible future work in this research field are proposed.
Recent progress in the study of graphene‐based noble‐metal nanocomposites is reviewed. Different strategies regarding the synthesis of noble‐metal nanostructures on graphene or its derivatives are presented. Their applications in electrocatalysis including the hydrogen evolution reaction, oxygen reduction reaction, alcohol oxidation reaction, and CO2 reduction reaction are discussed.
The Planck mission detected a positive correlation between the intensity (T) and B-mode polarization of the Galactic thermal dust emission. The TB correlation is a parity-odd signal, whose ...statistical mean vanishes in models with mirror symmetry. Recent work has shown, with strong evidence, that local handedness of the misalignment between the dust filaments and the sky-projected magnetic field produces TB signals. However, it remains unclear whether the observed global TB signal is caused by statistical fluctuations of magnetic misalignment angles or whether some parity-violating physics in the interstellar medium sets a preferred misalignment handedness. The present work aims to make a quantitative statement about how confidently the statistical fluctuation interpretation is ruled out by filament-based simulations of polarized dust emission. We use the publicly available DUSTFILAMENTS code to simulate the dust emission from filaments whose magnetic misalignment angles are symmetrically randomized and construct the probability density function of ξp, a weighted sum of the TB power spectrum. We find that the Planck data have a ≳10σ tension with the simulated ξp distribution. Our results strongly support the idea that the Galactic filament misalignment has a preferred handedness, whose physical origin is yet to be identified.
Change detection plays a crucial role in remote sensing by identifying surface modifications between two sets of temporal remote sensing images. Recent advancements in deep learning techniques have ...yielded significant achievements in this field. However, there are still some challenges: (1) Existing change feature fusion methods often introduce redundant information. (2) The complexity of network structures leads to a large number of parameters and difficulties in model training. To overcome these challenges, this paper proposes a Multi-Scale Feature Subtraction Fusion Network (MFSF-Net). It comprises two primary modules: the Multi-scale Feature Subtraction Fusion (MFSF) module and the Feature Deep Supervision (FDS) module. MFSF enhances change features and reduces redundant pseudo-change features. FDS provides additional supervision on different scales of change features in the decoder, improving the training efficiency performance of the network. Additionally, to address the problem of imbalanced samples, the Dice loss strategy is introduced as a means to mitigate this issue. Through comprehensive experiments, MFSF-Net achieves an F1 score of 91.15% and 95.64% on LEVIR-CD and CDD benchmark datasets, respectively, outperforming six state-of-the-art algorithms. Moreover, it attains an improved balance between model complexity and performance, showcasing the efficacy of the proposed approach.
Nanotubular Fe2O3 is a promising photoanode material, and producing morphologies that withstand high‐temperature calcination (HTC) is urgently needed to enhance the photoelectrochemical (PEC) ...performance. This work describes the design and fabrication of Fe2O3 nanotube arrays that survive HTC for the first time. By introducing a ZrO2 shell on hydrothermal FeOOH nanorods by atomic layer deposition, subsequent high‐temperature solid‐state reaction converts FeOOH‐ZrO2 nanorods to ZrO2‐induced Fe2O3 nanotubes (Zr‐Fe2O3 NTs). The structural evolution of the hematite nanotubes is systematically explored. As a result of the nanostructuring and shortened charge collection distance, the nanotube photoanode shows a greatly improved PEC water oxidation activity, exhibiting a photocurrent density of 1.5 mA cm−2 at 1.23 V (vs. reversible hydrogen electrode, RHE), which is the highest among hematite nanotube photoanodes without co‐catalysts. Furthermore, a Co‐Pi decorated Zr‐Fe2O3 NT photoanode reveals an enhanced onset potential of 0.65 V (vs. RHE) and a photocurrent of 1.87 mA cm−2 (at 1.23 V vs. RHE).
Survival training: Hematite nanotube arrays (Fe2O3‐NTs) surviving high‐temperature calcination were prepared by a solid‐state reaction between an FeOOH nanorod core and a ZrO2 shell. Their greatly improved photoelectrochemical water oxidation performance originates from their nanostructured morphology and shortened charge collection distance (see picture; W=depletion layer width).
Heterostructured, including heterophase, noble-metal nanomaterials have attracted much interest due to their promising applications in diverse fields. However, great challenges still remain in the ...rational synthesis of well-defined noble-metal heterophase nanostructures. Herein, we report the preparation of Pd nanoparticles with an unconventional hexagonal close-packed (2H type) phase, referred to as 2H-Pd nanoparticles, via a controlled phase transformation of amorphous Pd nanoparticles. Impressively, by using the 2H-Pd nanoparticles as seeds, Au nanomaterials with different crystal phases epitaxially grow on the specific exposed facets of the 2H-Pd, i.e., face-centered cubic (fcc) Au (fcc-Au) on the (002)h facets of 2H-Pd while 2H-Au on the other exposed facets, to achieve well-defined fcc-2H-fcc heterophase Pd@Au core–shell nanorods. Moreover, through such unique facet-directed crystal-phase-selective epitaxial growth, a series of unconventional fcc-2H-fcc heterophase core–shell nanostructures, including Pd@Ag, Pd@Pt, Pd@PtNi, and Pd@PtCo, have also been prepared. Impressively, the fcc-2H-fcc heterophase Pd@Au nanorods show excellent performance toward the electrochemical carbon dioxide reduction reaction (CO2RR) for production of carbon monoxide with Faradaic efficiencies of over 90% in an exceptionally wide applied potential window from −0.9 to −0.4 V (versus the reversible hydrogen electrode), which is among the best reported CO2RR catalysts in H-type electrochemical cells.
Multimodal bio-signals acquisition based on wearable devices and using virtual reality (VR) as stimulus source are promising techniques in emotion recognition research field. Numerous studies have ...shown that emotional states can be better evoked through Immersive Virtual Environments (IVE). The main goal of this paper is to provide researchers with a system for emotion recognition in VR environments. In this paper, we present a wearable forehead bio-signals acquisition pad which is attached to Head-Mounted Displays (HMD), termed HMD Bio Pad. This system can simultaneously record emotion-related two-channel electroencephalography (EEG), one-channel electrodermal activity (EDA), photoplethysmograph (PPG) and skin temperature (SKT) signals. In addition, we develop a human-computer interaction (HCI) interface which researchers can carry out emotion recognition research using VR HMD as stimulus presentation device. To evaluate the performance of the proposed system, we conducted different experiments to validate the multimodal bio-signals quality, respectively. To validate EEG signal, we have assessed the performance in terms of EEG eyes-blink task and eyes-open and eyes-closed task. The EEG eyes-blink task indicates that the proposed system can achieve comparable EEG signal quality in comparison to the dedicated bio-signals measuring device. The eyes-open and eyes-closed task proves that the proposed system can efficiently record alpha rhythm. Then we used signal-to-noise ratio (SNR) and Skin Conductance Reaction (SCR) signal to validate the performance for EDA acquisition system. A filtered EDA signal, with a high mean SNR of 28.52 dB, is plotted on HCI interface. Moreover, the SCR signal related to stimulus response can be correctly extracted from EDA signal. The SKT acquisition system has been validated effectively by the temperature change experiment when subjects are in unpleasant emotion. The pulse rate (PR) estimated from PPG signal achieved the low mean average absolute error (AAE), which is 1.12 beats per minute (BPM) over 8 recordings. In summary, the proposed HMD Bio Pad offers a portable, comfortable and easy-to-wear device for recording bio-signals. The proposed system could contribute to emotion recognition research in VR environments.
The inconsistent Hubble constant values derived from cosmic microwave background (CMB) observations and from local distance-ladder measurements may suggest new physics beyond the standard ACDM ...paradigm. It has been found in earlier studies that, at least phenomenologically, non-standard recombination histories can reduce the ≳ 4δ Hubble tension to ∼ 2δ. Following this path, we vary physical and phenomenological parameters in RECFAST, the standard code to compute ionization history of the universe, to explore possible physics beyond standard recombination. We find that the CMB constraint on the Hubble constant is sensitive to the hydrogen ionization energy and 2
s
→ 1
s
two-photon decay rate, both of which are atomic constants, and is insensitive to other details of recombination. Thus, the Hubble tension is very robust against perturbations of recombination history, unless exotic physics modifies the atomic constants during the recombination epoch.
We compute the cosmic microwave background temperature bispectrum generated by nonlinearities at recombination on all scales. We use CosmoLib2nd, a numerical Boltzmann code at second order to compute ...cosmic microwave background bispectra on the full sky. We consistently include all effects except gravitational lensing, which can be added to our result using standard methods. The bispectrum is peaked on squeezed triangles and agrees with the analytic approximation in the squeezed limit at the few percent level for all the scales where this is applicable. On smaller scales, we recover previous results on perturbed recombination. For cosmic-variance limited data to l(max)=2000, its signal-to-noise ratio is S/N=0.47, corresponding to f(NL)(eff)=-2.79, and will bias a local signal by f(NL)(loc) ~/= 0.82.
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