52 research outputs found

    Observational constraints on cosmic neutrinos and dark energy revisited

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    Using several cosmological observations, i.e. the cosmic microwave background anisotropies (WMAP), the weak gravitational lensing (CFHTLS), the measurements of baryon acoustic oscillations (SDSS+WiggleZ), the most recent observational Hubble parameter data, the Union2.1 compilation of type Ia supernovae, and the HST prior, we impose constraints on the sum of neutrino masses (\mnu), the effective number of neutrino species (\neff) and dark energy equation of state (ww), individually and collectively. We find that a tight upper limit on \mnu can be extracted from the full data combination, if \neff and ww are fixed. However this upper bound is severely weakened if \neff and ww are allowed to vary. This result naturally raises questions on the robustness of previous strict upper bounds on \mnu, ever reported in the literature. The best-fit values from our most generalized constraint read \mnu=0.556^{+0.231}_{-0.288}\rm eV, \neff=3.839\pm0.452, and w=−1.058±0.088w=-1.058\pm0.088 at 68% confidence level, which shows a firm lower limit on total neutrino mass, favors an extra light degree of freedom, and supports the cosmological constant model. The current weak lensing data are already helpful in constraining cosmological model parameters for fixed ww. The dataset of Hubble parameter gains numerous advantages over supernovae when w=−1w=-1, particularly its illuminating power in constraining \neff. As long as ww is included as a free parameter, it is still the standardizable candles of type Ia supernovae that play the most dominant role in the parameter constraints.Comment: 39 pages, 15 figures, 7 tables, accepted to JCA

    Void Lensing in Cubic Galileon Gravity

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    Weak lensing studies via cosmic voids are a promising probe of Modified Gravity (MG). Excess surface mass density (ESD) is widely used as a lensing statistic in weak lensing research. In this paper, we use the ray-tracing method to study the ESD around voids in simulations based on Cubic Galileon (CG) gravity. With the compilation of N-body simulation and ray-tracing method, changes in structure formation and deflection angle resulting from MG can both be considered, making the extraction of lensing signals more realistic. We find good agreements between the measurement and theoretical prediction of ESD for CG gravity. Meanwhile, the lensing signals are much less affected by the change of the deflection angle than the change of the structure formation, indicating a good approximation of regarding ESD (statistics) as the projection of 3D dark matter density field. Finally, we demonstrate that it is impossible to distinguish CG and General Relativity in our simulation, however, in the next-generation survey, thanks to the large survey area and the increased galaxy number density, detecting the differences between these two models is possible. The methodology employed in this paper that combines N-body simulation and ray-tracing method can be a robust way to measure the lensing signals from simulations based on the MGs, and especially on that which significantly modifies the deflection angle.Comment: 14 pages, 9 figure

    Assessing mass-loss and stellar-to-halo mass ratio of satellite galaxies: a galaxy–galaxy lensing approach utilizing DECaLS DR8 data

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    The galaxy–galaxy lensing technique allows us to measure the subhalo mass of satellite galaxies, studying their mass-loss and evolution within galaxy clusters and providing direct observational validation for theories of galaxy formation. In this study, we use the weak gravitational lensing observations from Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys DR8, in combination with the redMaPPer galaxy cluster catalogue from Sloan Digital Sky Survey (SDSS) DR8 to accurately measure the dark matter halo mass of satellite galaxies. We confirm a significant increase in the stellar-to-halo mass ratio of satellite galaxies with their halo-centric radius, indicating clear evidence of mass-loss due to tidal stripping. Additionally, we find that this mass-loss is strongly dependent on the mass of the satellite galaxies, with satellite galaxies above experiencing more pronounced mass-loss compared to lower mass satellites, reaching 86 per cent at projected halo-centric radius 0.5R200c. The average mass-loss rate, when not considering halo-centric radius, displays a U-shaped variation with stellar mass, with galaxies of approximately exhibiting the least mass-loss, around 60 per cent. We compare our results with state-of-the-art hydrodynamical numerical simulations and find that the satellite galaxy stellar-to-halo mass ratio in the outskirts of galaxy clusters is higher compared to the predictions of the Illustris-TNG project about factor 5. Furthermore, the Illustris-TNG project’s numerical simulations did not predict the observed dependence of satellite galaxy mass-loss rate on satellite galaxy mass

    Demographic and net primary productivity dynamics of primary and secondary tropical forests in Southwest China under a changing climate

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    Tropical forests are major carbon sinks on the Earth's land surface. However, our understanding of how the demographic rate and carbon sink capacities of tropical forests respond to climate change remains limited. In this study, we investigated the impacts of environmental drivers on forest growth, mortality, recruitment, and stem net primary productivity (NPPstem) over 16 years at five tropical forest plots in Xishuangbanna, Southwest China. These plots are along a successional gradient spanning three tropical secondary forests (tropical secondary forest‐1 [TSF‐1], tropical secondary forest‐2 [TSF‐2], and tropical secondary forest‐3 [TSF‐3]) and two primary forests (tropical rainforest [TRF] and tropical karst forest [TKF]). Our results showed that early successional secondary forests (TSF‐2 and TSF‐3) had higher diameter growth rates and relative mortality rates. An extreme drought event during 2009–2010 reduced the growth rate, relative recruitment rate, and NPPstem for most plots while increasing mortality in early successional forest plots. We observed significant negative effects of maximum temperature (Tmax) on NPPstem and diameter growth rate across all plots. Additionally, we found that precipitation had significant positive effects on diameter growth rate across all plots. Furthermore, tree mortality increased with rising Tmax, whereas precipitation significantly enhanced tree recruitment. Our findings highlight the vulnerability of tree growth, mortality, recruitment, and productivity in tropical forests to extreme drought events in Southwest China. Continued climate warming and more frequent droughts will induce higher mortality rates and impede growth, thus reducing the carbon sink capacity of tropical forests, especially in early successional stage tropical secondary forests

    Upconversion NaYF 4

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    Upconversion nanoparticles (UCNPs) based on NaYF4 nanocrystals with strong upconversion luminescence are synthesized by the solvothermal method. The emission color of these NaYF4 upconversion nanoparticles can be easily modulated by the doping. These NaYF4 upconversion nanocrystals can be employed as fluorescence donors to pump fluorescent organic molecules. For example, the efficient luminescence resonant energy transfer (LRET) can be achieved by controlling the distance between NaYF4:Yb3+/Er3+ UCNPs and Rhodamine B (RB). NaYF4:Yb3+/Er3+ UCNPs can emit green light at the wavelength of ~540 nm while RB can efficiently absorb the green light of ~540 nm to emit red light of 610 nm. The LRET efficiency is highly dependent on the concentration of NaYF4 upconversion fluorescent donors. For the fixed concentration of 3.2 ”g/mL RB, the optimal concentration of NaYF4:Yb3+/Er3+ UCNPs is equal to 4 mg/mL which generates the highest LRET signal ratio. In addition, it is addressed that the upconversion nanoparticles with diameter of 200 nm are suitable for imaging the cells larger than 10 ”m with clear differentiation between cell walls and cytoplasm

    Validity of patients' online reviews at direct-to-consumer teleconsultation platforms:a protocol for a cross-sectional study using unannounced standardised patients

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    Introduction As direct-to-consumer teleconsultation (hereafter referred to as ‘teleconsultation’) has gained popularity, an increasing number of patients have been leaving online reviews of their teleconsultation experiences. These reviews can help guide patients in identifying doctors for teleconsultation. However, few studies have examined the validity of online reviews in assessing the quality of teleconsultation against a gold standard. Therefore, we aim to use unannounced standardised patients (USPs) to validate online reviews in assessing both the technical and patient-centred quality of teleconsultations. We hypothesise that online review results will be more consistent with the patient-centred quality, rather than the technical quality, as assessed by the USPs.Methods and analysis In this cross-sectional study, USPs representing 11 common primary care conditions will randomly visit 253 physicians via the three largest teleconsultation platforms in China. Each physician will receive a text-based and a voice/video-based USP visit, resulting in a total of 506 USP visits. The USP will complete a quality checklist to assess the proportion of clinical practice guideline-recommended items during teleconsultation. After each visit, the USP will also complete the Patient Perception of Patient-Centeredness Rating. The USP-assessed results will be compared with online review results using the intraclass correlation coefficient (ICC). If ICC >0.4 (p<0.05), we will assume reasonable concordance between the USP-assessed quality and online reviews. Furthermore, we will use correlation analysis, Lin’s Coordinated Correlation Coefficient and Kappa as supplementary analyses.Ethics and dissemination This study has received approval from the Institutional Review Board of Southern Medical University (#Southern Medical Audit (2022) No. 013). Results will be actively disseminated through print and social media, and USP tools will be made available for other researchers.Trial registration The study has been registered at the China Clinical Trials Registry (ChiCTR2200062975)

    Inflation and Dark Energy from spectroscopy at z > 2

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    Cosmological Synergies Enabled by Joint Analysis of Multi-probe data from WFIRST, Euclid, and LSST

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    WFIRST, Euclid, and LSST are all missions designed to perform dedicated cosmology surveys that offer unprecedented statistical constraining power and control of systematic uncertainties. There is a growing realization that these missions will be significantly more powerful when the data are processed and analyzed in unison

    Effects of Acupuncture on Hospitalized Patients with Urinary Retention

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    Objective. The aim of this study was to investigate the effects of acupuncture on urinary retention and provide treatment suggestions. Methods. A total of 113 hospitalized patients with urinary retention were included in this study. The GV20, CV6, CV4, CV3, ST28, SP6, and SP9 points were selected as the main acupoints. Acupuncture therapy was conducted for 30 minutes per session. The total number of treatment sessions was determined by the symptoms and the length of hospital stay. Bladder postvoid residual urine volume (PVR) was measured pretreatment and posttreatment by ultrasonic. Efficacy defined as spontaneous urination and a residual urine volume <50 mL was measured. Results. The median number of acupuncture treatment sessions was 3 (range, 1–12 times). Acupuncture treatment significantly reduced the PVR (545.1 ± 23.9 mL vs 67.4 ± 10.7 mL; p<0.001). Among the 113 patients, 99 (87.6%) patients were cured and 8 (7.1%) patients were improved of their urinary retention. The remaining 6 (5.3%) patients’ urinary retention did not improve. The effective rate was 94.7%. There was significant difference in the efficacy rate between patients with one urinary catheterization and with two or more. Acupuncture treatment was not associated with side effects. Conclusion. Acupuncture is an effective and safe treatment option for urinary retention. Early application of acupuncture treatment should be considered in clinic, and repeated urinary catheter insertion and removal should be avoided. Our study suggests that a randomized controlled study with a large sample size to verify the efficacy of acupuncture for the treatment of urinary retention is warranted
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