We study the redshift distribution of two samples of early-type gravitational lenses, extracted from a larger collection of 122 systems, to constrain the cosmological constant in the LambdaCDM model ...and the parameters of a set of alternative dark energy models (XCDM, Dvali-Gabadadze-Porrati, and Ricci dark energy models), in a spatially flat universe. The likelihood is maximized for ohm sub(Lambda) = 0.70 + or - 0.09 when considering the sample excluding the Sloan Lens ACS systems (known to be biased toward large image-separation lenses) and no-evolution, and ohm sub(Lambda) = 0.81 + or - 0.05 when limiting to gravitational lenses with image separation Delta theta > 2" and no-evolution. In both cases, results accounting for galaxy evolution are consistent within 1sigma. The present test supports the accelerated expansion, by excluding the null hypothesis (i.e., ohm sub(Lambda) = 0) at more than 4sigma, regardless of the chosen sample and assumptions on the galaxy evolution. A comparison between competitive world models is performed by means of the Bayesian information criterion. This shows that the simplest cosmological constant model-that has only one free parameter-is still preferred by the available data on the redshift distribution of gravitational lenses. We perform an analysis of the possible systematic effects, finding that the systematic errors due to sample incompleteness, galaxy evolution, and model uncertainties approximately equal the statistical errors, with present-day data. We find that the largest sources of systemic errors are the dynamical normalization and the high-velocity cutoff factor, followed by the faint-end slope of the velocity dispersion function.
In this paper, we carry out an assessment of cosmic distance duality relation (CDDR) based on the latest observations of HII galaxies acting as standard candles and ultra-compact structure in radio ...quasars acting as standard rulers. Particularly, two machine learning reconstruction methods Gaussian Process (GP) and Artificial Neural Network (ANN) are applied to reconstruct the Hubble diagrams from observational data. We show that both approaches are capable of reconstructing the current constraints on possible deviations from the CDDR in the redshift range
z
∼
2.3
. Considering four different parametric methods of CDDR, which quantify deviations from the CDDR and the standard cosmological model, we compare the results of the two different machine learning approaches. It is observed that the validity of CDDR is in well agreement with the current observational data within
1
σ
based on the reconstructed distances through GP in the overlapping redshift domain. Moreover, we find that ultra-compact radio quasars could provide
10
-
3
-level constraints on the violation parameter at high redshifts, when combined with the observations of HII galaxies. In the framework of ANN, one could derive robust constraints on the violation parameter at a precision of
10
-
2
, with the validity of such distance duality relation within
2
σ
confidence level.
Fluorescence imaging technology has been extensively applied in chemical and biological research profiting from its high sensitivity and specificity. Much attention has been devoted to breaking the ...light diffraction–limited spatial resolution. However, it remains a great challenge to improve the axial resolution in a way that is accessible in general laboratories. Surface plasmon–coupled emission (SPCE), generated by the interactions between surface plasmons and excited fluorophores in close vicinity of the thin metal film, offers an opportunity for optical imaging with potential application in analysis of molecular and biological systems. Benefiting from the highly directional and distance-dependent properties, SPCE imaging (SPCEi) has displayed excellent performance in bioimaging with improved sensitivity and axial confinement. Herein, we give a brief overview of the development of SPCEi. We describe the unique optical characteristics and constructions of SPCEi systems and highlight recent advances in the use of SPCEi for biological applications. We hope this review provides readers with both the insights and future prospects of SPCEi as a new promising imaging platform for potentially widespread applications in biological research and medical diagnostics.
Graphical abstract
Against the background of global climate change and anthropogenic interference, studying the spatial and temporal heterogeneity of ecosystem services in important ecological function regions and ...rationally dividing the functional zones will help to promote the construction of the natural protected areas system dominated by national parks. The Shennongjia Region is an important candidate for China's national parks and one of the key pilots. Integrating the InVEST model, Getis-Ord Gi* index, hotspot analysis, GeoDetector and K-means clustering algorithm, we measured five ecosystem services interactions and delineate the functional zones. The results show that the spatial and temporal evolution of various ecosystem services in the Shennongjia Region between 2000 and 2020 was significant. All ecosystem services showed a decreasing and then increasing trend, except for carbon storage, which slowly declined. The ecological status of the region is in the process of polarization, with the local environment showed a trend of continuous deterioration. Water yield-habitat quality and carbon storage-water purification showed synergistic relationships; soil conservation showed trade-offs with water yield, carbon storage and water purification over a wide spatial range. The interaction between land surface temperature and vegetation cover was the most significant dominant factor. Hot spots for the comprehensive ecosystem services index were mainly located in the central and southern parts of the Shennongjia region and four types of ecosystem service functional zones were identified accordingly. This study is of great significance for maximizing the benefits of ecosystem service functions, the efficient allocation of environmental resources and the rational formulation of management policies in natural protected areas.
The assumptions of large-scale homogeneity and isotropy underly the familiar Friedmann-Lemaître-Robertson-Walker (FLRW) metric that appears to be an accurate description of our Universe. In this ...paper, we propose a new strategy of testing the validity of the FLRW metric, based on the galactic-scale lensing systems where strongly lensed gravitational waves and their electromagnetic counterparts can be simultaneously detected. Each strong lensing system creates opportunity to infer the curvature parameter of the Universe. Consequently, combined analysis of many such systems will provide a model-independent tool to test the validity of the FLRW metric. Our study demonstrates that the third-generation ground based GW detectors, like the Einstein Telescope (ET) and space-based detectors, like the Big Bang Observer (BBO), are promising concerning determination of the curvature parameter or possible detection of deviation from the FLRW metric. Such accurate measurements of the FLRW metric can become a milestone in precision GW cosmology.
Shennongjia is one of the most important ecological function areas and ecologically vulnerable zones in the world. With the rapid development of social economies, especially tourism, the ecological ...environment of Shennongjia has experienced profound changes. Exploring the characteristics and changing trends of ecological environment in Shennongjia will help to analyze the causes of the damage to the ecological environment, and build a vulnerability analysis framework with multi-scale, multi-element, multi-flow, and multi-circulation characteristics, which provides an effective research paradigm and analysis tool for the study of regional ecological vulnerability. With the support of RS and GIS technology, this study uses spatial principal component analysis (SPCA) and the vulnerability scoring diagram (VSD) model to comprehensively and quantitatively analyze the spatial and temporal evolution characteristics and driving forces of ecological vulnerability in Shennongjia from 1996 to 2018. The VSD model was selected to decompose the vulnerability into three components of "exposure-sensitivity-adaptation", and 16 indicators were selected to construct an ecological vulnerability evaluation system in Shennongjia, and the evaluation data were organized in a progressive and detailed way. (1) During the study period, the overall ecological vulnerability of Shennongjia is in a mild vulnerability level, exhibiting differentiation characteristics of high in the northeast and low in the southwest. High vulnerability zones are mainly distributed in the main towns and roads. (2) The risk of ecological vulnerability of the entire region presents the characteristics of continuous decline. (3) Land-use types, population density, and vegetation coverage are the main factors driving the evolution of ecological vulnerability. (4) A high level of coupling coordination exists between ecological vulnerability and landscape patterns. Analyses of the ecological vulnerability of Shennongjia shows that the entire region is in a mild vulnerability level. The extreme vulnerability risk of the ecological environment shows polarization. The evolution of ecological environment in Shennongjia is the result of the interaction between human activities and natural environment. This study offers an effective way to assess ecological vulnerability and provides some strategies and guidance for improving ecological security.
Abstract
The preparation of quantum systems and the execution of quantum information tasks between distant users are always affected by gravitational and relativistic effects. In this work, we ...quantitatively analyze how the curved space-time background of the Earth affects the classical and quantum correlations between photon pairs that are initially prepared in a two-mode squeezed state. More specifically, considering the rotation of the Earth, the space-time around the Earth is described by the Kerr metric. Our results show that these state correlations, which initially increase for a specific range of satellite’s orbital altitude, will gradually approach a finite value with increasing height of satellite’s orbit (when the special relativistic effects become relevant). More importantly, our analysis demonstrates that the changes of correlations generated by the total gravitational frequency shift could reach the level of
$$<0.5\%$$
<
0.5
%
within the satellite’s height at geostationary Earth orbits.
The cosmic curvature ( k) is a fundamental parameter for cosmology. In this paper, we propose an improved model-independent method to constrain the cosmic curvature, which is geometrically related to ...the Hubble parameter H(z) and luminosity distance DL(z). Using the currently largest H(z) sample from the well-known cosmic chronometers, as well as the luminosity distance DL(z) from the relation between the UV and X-ray luminosities of 1598 quasars and the newly compiled Pantheon sample including 1048 SNe Ia, 31 independent measurements of the cosmic curvature k(z) can be expected covering the redshift range of 0.07 < z < 2. Our estimation of k(z) is fully compatible with flat universe at the current level of observational precision. Meanwhile, we find that, for the Hubble diagram of 1598 quasars as a new type of standard candle, the spatial curvature is constrained to be k = 0.08 0.31. For the latest Pantheon sample of SNe Ia observations, we obtain k = − 0.02 0.14. Compared to other approaches aiming for model-independent estimations of spatial curvature, our analysis also achieves constraints with competitive precision. More interestingly, it is suggested that the reconstructed curvature k is negative in the high-redshift region, which is also consistent with the results from the model-dependent constraints in the literature. Such findings are confirmed by our reconstructed evolution of k(z), in the framework of a model-independent method of Gaussian processes (GP) without assuming a specific form.
It is well known that de Sitter(dS) black holes generally have a black hole horizon and a cosmological horizon, both of which have Hawking radiation. But the radiation temperature of the two horizons ...is generally different, so dS black holes do not meet the requirements of thermal equilibrium stability, which brings certain difficulties to the study of the thermodynamic characteristics of black holes. In this paper, dS black hole is regarded as a thermodynamic system, and the effective thermodynamic quantities of the system are obtained. The influence of various state parameters on the effective thermodynamic quantities in the massive gravity space-time is discussed. The condition of the phase transition of the de Sitter black hole in massive gravity space-time is given. We consider that the total entropy of the dS black hole is the sum of the corresponding entropy of the two horizons plus an extra term from the correlation of the two horizons. By comparing the entropic force of interaction between black hole horizon and the cosmological horizon with Lennard-Jones force between two particles, we find that the change rule of entropic force between the two system is surprisingly the same. The research will help us to explore the real reason of accelerating expansion of the universe.
ABSTRACT
In this paper, we present a model-independent approach to calibrate the largest quasar sample. Calibrating quasar samples is essentially constraining the parameters of the linear relation ...between the log of the ultraviolet (UV) and X-ray luminosities. This calibration allows quasars to be used as standardized candles. There is a strong correlation between the parameters characterizing the quasar luminosity relation and the cosmological distances inferred from using quasars as standardized candles. We break this degeneracy by using Gaussian process regression to model-independently reconstruct the expansion history of the Universe from the latest type Ia supernova observations. Using the calibrated quasar data set, we further reconstruct the expansion history up to redshift of z ∼ 7.5. Finally, we test the consistency between the calibrated quasar sample and the standard Lambda cold dark matter ($\rm {\Lambda }CDM$) model based on the posterior probability distribution of the GP hyperparameters. Our results show that the quasar sample is in good agreement with the standard $\rm {\Lambda }CDM$ model in the redshift range of the supernova, despite the 2−3σ significant deviations taking place at higher redshifts. Fitting the standard $\rm {\Lambda }CDM$ model to the calibrated quasar sample, we obtain a high value of the matter density parameter $\Omega _m = 0.382^{+0.045}_{-0.042}$, which is marginally consistent with the constraints from other cosmological observations.
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