Toward a direct measurement of the cosmic acceleration: The first observation of HI 21cm absorption line at FAST

In this work, we report the first result from the investgation of Neutral atomic hydrogen(HI) 21cm absorption line in spectrum of PKS1413+135 as a associated type at redshift $z\approx 0.24670041$ observed by FAST using the observing time of 10 minutes for the absorber and the spectral resolution of the raw data was setted to 10 Hz. The full spectral profile is analysed by fitting the absorption line with single Gaussian function as the resolution of 10kHz in 2MHz bandwidth, eventually intending to illustrate the latest cosmic acceleration by the direct measurement of time evolution of the redshift of HI 21cm absorption line with Hubble flow toward a same background Quasar in the time interval of more than a decade or many years as a detectable signal that produced by the accelerated expansion of the Universe in the era of FAST at low redshift space,namely redshift drift $\dot{z}$ or SL effect. The obtained HI gas column density $\rm N_{HI} \approx 2.2867\times 10^{22}/cm^2$ of this DLA system, much equivalent to the originally observed value $\rm N_{HI} \approx 1.3\times 10^{19}\times(T_s/f)/cm^2$ within the uncertainties of the spin temperature of a spiral host galaxy, and the signal to noise ratio SNR highly reaching 57.4357 for the resolution of 10kHz evidently validates the opportunities of the HI 21cm absorption lines of DLA systems to enforce the awareness of the physical motivation of dark energy by the probe of $\rm\dot{z}$ with the enhancement of accuracy in the level of $\sim 10^{-10}$ per decade.Comment: 26 pages,8 figures, 3 tables, submitted to JCA

Detection of dark matter Skewness in the VIRMOS-DESCART survey: Implications for \Omega_0

Weak gravitational lensing provides a direct statistical measure of the dark matter distribution. The variance is easiest to measure, which constrains the degenerate product \sigma_8\Omega^0.6. The degeneracy is broken by measuring the skewness arising from the fact that densities must remain positive, which is not possible when the initially symmetric perturbations become non-linear. Skewness measures the non-linear mass scale, which in combination with the variance measures \Omega directly. We present the first detection of dark matter skewness from the Virmos-Decart survey. We have measured the full three point function, and its projections onto windowed skewness. We separate the lensing mode and the B mode. The lensing skewness is detected for a compensated Gaussian on scales of 5.37 arc minutes to be \kappa^3=1.06+/-0.06x10^-6. The B-modes are consistent with zero at this scale. The variance for the same window function is \kappa^2= 5.32+/-0.62+/-0.98x10^-5, resulting in S_3=375^{+342}_{-124}. Comparing to N-body simulations, we find \Omega_0<0.5 at 90% confidence. The Canada-France-Hawaii-Telescope legacy survey and newer simulations should be able to improve significantly on the constraint.Comment: 26 pages 8 figures, accepted by ApJ, minor revisions, corrected eqn (21

Enhancement of Innate Immune Function in Mice by Bifidobacterium bifidum FL-228.1

In this study, eight potential functional strains were selected to interfered with RAW264.7 murine macrophages and human peripheral blood mononuclear cells (PBMCs). Then, changes in phagocytic activity of RAW264.7 cells and natural killer (NK) cell activity were detected and the screened potential probiotics were further intervened in BALB/c mice to explore their immunomodulatory efficacy in vivo. In cell experiments, the results showed that the intervention of different strains significantly increased the phagocytic activity of RAW264.7 cells (P0.05). In conclusion, Bifidobacterium bifidum FL-228.1 can improve innate immune function and have a more comprehensive effect on the immune system by regulating immune cell activity, cytokine expression and mRNA levels of immune molecules related to antimicrobial peptides

OP9-Lhx2 stromal cells facilitate derivation of hematopoietic progenitors both in vitro and in vivo

AbstractGenerating engraftable hematopoietic stem cells (HSCs) from pluripotent stem cells (PSCs) is an ideal approach for obtaining induced HSCs for cell therapy. However, the path from PSCs to robustly induced HSCs (iHSCs) in vitro remains elusive. We hypothesize that the modification of hematopoietic niche cells by transcription factors facilitates the derivation of induced HSCs from PSCs. The Lhx2 transcription factor is expressed in fetal liver stromal cells but not in fetal blood cells. Knocking out Lhx2 leads to a fetal hematopoietic defect in a cell non-autonomous role. In this study, we demonstrate that the ectopic expression of Lhx2 in OP9 cells (OP9-Lhx2) accelerates the hematopoietic differentiation of PSCs. OP9-Lhx2 significantly increased the yields of hematopoietic progenitor cells via co-culture with PSCs in vitro. Interestingly, the co-injection of OP9-Lhx2 and PSCs into immune deficient mice also increased the proportion of hematopoietic progenitors via the formation of teratomas. The transplantation of phenotypic HSCs from OP9-Lhx2 teratomas but not from the OP9 control supported a transient repopulating capability. The upregulation of Apln gene by Lhx2 is correlated to the hematopoietic commitment property of OP9-Lhx2. Furthermore, the enforced expression of Apln in OP9 cells significantly increased the hematopoietic differentiation of PSCs. These results indicate that OP9-Lhx2 is a good cell line for regeneration of hematopoietic progenitors both in vitro and in vivo

Human respiratory syncytial virus subgroups A and B outbreak in a kindergarten in Zhejiang Province, China, 2023

BackgroundIn May–June 2023, an unprecedented outbreak of human respiratory syncytial virus (HRSV) infections occurred in a kindergarten, Zhejiang Province, China. National, provincial, and local public health officials investigated the cause of the outbreak and instituted actions to control its spread.MethodsWe interviewed patients with the respiratory symptoms by questionnaire. Respiratory samples were screened for six respiratory pathogens by real-time quantitative polymerase chain reaction (RT-PCR). The confirmed cases were further sequenced of G gene to confirm the HRSV genotype. A phylogenetic tree was reconstructed by maximum likelihood method.ResultsOf the 103 children in the kindergarten, 45 were classified as suspected cases, and 25 cases were confirmed by RT-PCR. All confirmed cases were identified from half of classes. 36% (9/25) were admitted to hospital, none died. The attack rate was 53.19%. The median ages of suspected and confirmed cases were 32.7 months and 35.8 months, respectively. Nine of 27 confirmed cases lived in one community. Only two-family clusters among 88 household contacts were HRSV positive. A total of 18 of the G gene were obtained from the confirmed cases. Phylogenetic analyses revealed that 16 of the sequences belonged to the HRSV B/BA9 genotype, and the other 2 sequences belonged to the HRSV A/ON1 genotype. The school were closed on June 9 and the outbreak ended on June 15.ConclusionThese findings suggest the need for an increased awareness of HRSV coinfections outbreak in the kindergarten, when HRSV resurges in the community after COVID-19 pandemic

Security Issues in Cognitive Radio Networks

Cognitive radio is an emerging trend to solve the problem of scarce spectrum resources in the prosperous area of wireless communication. By dynamically utilizing unoccupied spectrums of primary (licensed) users, secondary (unlicensed) users can meet their own communication requirements. While traditional security attacks on wireless networks still exist, the cognitive radio technologies bring unique security challenges. Current literature on solving these problems assume a central authority, which, for example, assumes the role of a fusion centre. Dynamic wireless environments are composed of users from different competing wireless operators, and assuming the existence of a central authority is a major restriction. We propose approaches that do not rely on these centralized assumptions, and are thus more applicable to practical cognitive radio networks. Cooperative sensing is an effective solution to improve sensing accuracy and robustness in the presence of fading and shadowing that make individual sensing less reliable. However, when an adversary can corrupt some nodes in the network, the effectiveness of cooperative sensing may degrade dramatically. We design the first fully distributed security scheme, ReDiSen, to defend such attacks in cooperative sensing. We apply reputation generated from exchanged sensing results as an aid to restrict the impact of malicious behaviours. Both theoretical analysis and simulation results indicate that ReDiSen provides an effective countermeasure against security attacks by enabling secondary users to obtain more accurate cooperative sensing results in an adversarial environment. ReDiSen does not rely on a central authority, and is therefore more applicable in dynamic cognitive radio networks. In a cognitive radio network, selfish secondary users may not voluntarily contribute to the desired cooperative sensing process. We design the first fully distributed scheme to incentivize node participation in cooperative sensing, by connecting sensing and spectrum allocation, and offering incentive from the latter to the former. Secondary users who are more active and report more accurate sensing values are given higher reputation values, which in turn lead to lower prices in the spectrum allocation phase. Theoretical analysis and simulation results indicate that the proposed method effectively incentivizes sensing participation, and rewards truthful and accurate reporting. Our proposed system is fully distributed and does not rely on a central authority, and so is more applicable in dynamic cognitive radio networks in practice. We also show how to improve the robustness of reputation when malicious nodes report spurious reputation. VCG (Vickrey-Clarke-Groves) spectrum auctions represent a classic type of truthful spectrum allocation method in cognitive radio networks. While security and privacy issues recently start to draw attention in such spectrum auctions, there exists little work that examines the scenario where the auctioneer is not fully trustworthy. We present the first verifiable VCG spectrum auction that allows verification of the winner determination and pricing phases of the VCG auction. We use maximal independent set enumeration and secure multiparty computation to solve the verification problem, while protecting privacy of wireless users. We propose different methods in different steps of the verification scheme, and analyze the effectiveness, information leakage, and efficiency. Our scheme does not rely on a third party, does not alter the auction process, and by using an offline verification process, does not introduce extra delay to the auction process

Chemical Recycling of Poly(ethylene terephthalate): Effects of Mechanical Stress and Radiation Damage on Hydrolysis

Finding an effective recycling process for oceanic plastic waste is increasingly important to address environmental pollution. Plastic waste is a bountiful and sustainable resource for energy production and chemical recycling. Polyethylene terephthalate (PET), one of the most common commercialized polymers, is promising to be recycled by hydrolysis. The objective of this work was to study the effects of mechanical stress and radiation damage on PET structure and hydrolysis reactivity. Ball-milling and photo-damaging pretreatments were carried out to imitate the environmental degradation in the ocean environment. An evident decrease in crystallinity with increasing ball-milling time was observed. This decrease in crystallinity caused by fractures of chemical bonds induced by photoaging and ball-milling treatments were investigated. PET was hydrolyzed into ethylene glycol (EG) and terephthalic acid (TPA) at 200°C in tube hydrolysis reactors without catalysts. EG and TPA were recovered after PET depolymerization. Thermogravimetric analysis and Fourier-transform infrared spectroscopy indicated that the recovered TPA was purified. Qualitative and quantitative analysis of TPA and EG were performed by using UV-Visible spectrophotometer and High-Performance Liquid Chromatograph (HPLC) separately. At 200 ℃, the conversion rate of fresh and ball-milled PET samples was improved from 16-18% with a one-hour reaction time compared to 87-91% with a two-hour reaction time. This depolymerization behavior supported that the conversion rate of PET was increased with increasing reaction time at the same temperature. The experiment results, however, showed PET conversion, TPA yield, and EG yield did not improve after ball-milling and photo-damaging treatment. After retention time of 1 hour, PET conversions, yields of TPA, yields of EG of various PET samples were 16.5±1.5%, 11.5±1.5% and 0.70 ± 0.20%, respectively. Mechanical treatment and radiation damage did not affect PET reactivity significantly in this experiment. Two main reasons were discussed to explain this result. The effect of radiation damage and mechanical stress was obscured by the more dominant reaction condition, temperature. The pretreatments in this experiment were not strong enough to affect PET reactivity. Based on the current results, recommendations for the hydrolysis temperature, potential catalysts, and more robust pretreatment methods were provided for further outlook of studying environmental effects on PET hydrolysis

Studies on the airborne bacterial communities and antimicrobial resistance genes in duck houses based on metagenome and PCR analysis

ABSTRACT: The threat of antimicrobial resistance (AMR) is on the rise globally, especially with the development of animal husbandry and the increased demand for antibiotics. Livestock and poultry farms, as key sites for prevalence of antibiotic-resistant bacteria (ARB), can spread antimicrobial resistance genes (ARGs) through microbial aerosols and affect public health. In this study, total suspended particulate matter (TSP) and airborne culturable microorganisms were collected from duck houses in Tai'an, Shandong Province, and the bacterial communities and airborne ARGs were analyzed using metagenomics and PCR methods. The results showed that the bacterial communities in the air of duck houses were mainly Actinobacteria, Firmicutes, Proteobactria, Chlamydia, and Bcateroidetes at the phylum level. At the genus level, the air was dominated by Corynebacterium, Jeotgalicoccus, Staphylococcus, Brevibacterium, and Megacoccus, and contained some pathogenic bacteria such as Staphylococcus aureus, Corynebacterium diphtheriae, Klebsiella oxytoca, Acinetobacter baumannii, and Pseudomonas aeruginosa, which were also potential hosts for ARGs. The airborne ARGs were mainly macrolides (10.97%), penicillins (10.73%), cephalosporins (8.91%), streptozotocin (8.91%), and aminoglycosides (8.02%). PCR detected 27 ARGs in airborne culturable microorganisms, and comparative analysis between PCR and the metagenomic data revealed that a total of 9 ARGs were found to the same, including macrolides ErmA, ErmF, tetracyclines tetG, tetX, methicarbamazepines dfrA12, dfrA15, aminoglycosides APH3-VI, ANT2-Ⅰ, and sulfonamides sul2. Moreover, inhalation exposure modeling showed that the workers in duck houses inhaled higher concentrations of ARB, human pathogenic bacteria (HPB) and human pathogenic antibiotic-resistant bacteria (HPARB) than hospital workers. These results provide new insights into airborne microorganisms and ARGs in animal farms and lay the foundation for further study

A RAPD based study revealing a previously unreported wide range of mesophilic and thermophilic spore formers associated with milk powders in China

Aerobic spore forming bacteria are potential milk powder contaminants and are viewed as indicators of poor quality. A total of 738 bacteria, including both mesophilic and thermophilic, isolated from twenty-five powdered milk samples representative of three types of milk powders in China were analyzed based on the random amplified polymorphic DNA (RAPD) protocol to provide insight into species diversity. Bacillus licheniformis was found to be the most prevalent bacterium with greatest diversity (~ 43% of the total isolates) followed by Geobacillus stearothermophilus (~ 21% of the total isolates). Anoxybacillus flavithermus represented only 8.5% of the total profiles. Interestingly, actinomycetes represented a major group of the isolates with the predominance of Laceyella sacchari followed by Thermoactinomyces vulgaris, altogether comprising of 7.3% of the total isolates. Out of the nineteen separate bacterial species (except five unidentified groups) recovered and identified from milk powders, twelve proved to belong to novel or previously unreported species in milk powders. Assessment and characterization of the harmful effects caused by this particular micro-flora on the quality and safety of milk powders will be worth doing in the future