Quasinormal modes of black holes in f(T) gravity

We calculate the quasinormal modes (QNM) frequencies of a test massless scalar field and an electromagnetic field around static black holes in $f(T)$ gravity. Focusing on quadratic $f(T)$ modifications, which is a good approximation for every realistic $f(T)$ theory, we first extract the spherically symmetric solutions using the perturbative method, imposing two ans$\ddot{\text{a}}$tze for the metric functions, which suitably quantify the deviation from the Schwarzschild solution. Moreover, we extract the effective potential, and then calculate the QNM frequency of the obtained solutions. Firstly, we numerically solve the Schr$\ddot{\text{o}}$dinger-like equation using the discretization method, and we extract the frequency and the time evolution of the dominant mode applying the function fit method. Secondly, we perform a semi-analytical calculation by applying the WKB method with the Pade approximation. We show that the results for $f(T)$ gravity are different compared to General Relativity, and in particular we obtain a different slope and period of the field decay behavior for different model parameter values. Hence, under the light of gravitational-wave observations of increasing accuracy from binary systems, the whole analysis could be used as an additional tool to test General Relativity and examine whether torsional gravitational modifications are possible.Comment: 22 pages, 7 figure

Hepatitis C Seroprevalence and Associated Risk Factors, Anyang, China

Hepatitis C virus screening was conducted among 8,226 residents 25–65 years of age in 4 counties of China; virus prevalence was 0.9%. A subsequent case–control study indicated blood transfusion (odds ratio [OR] 4.55), esophageal balloon examination (OR 3.78), and intravenous injection (OR 5.83) were associated with infection

The effective field theory approach to the strong coupling issue in f(T)f(T) gravity

We investigate the scalar perturbations and the possible strong coupling issues of $f(T)$ around a cosmological background, applying the effective field theory (EFT) approach. We revisit the generalized EFT framework of modified teleparallel gravity and apply it by considering both linear and second-order perturbations for $f(T)$ theory. No new scalar mode is present in linear and second-order perturbations in $f(T)$ gravity, which suggests a strong coupling problem. However, based on the ratio of cubic to quadratic Lagrangians, we provide a simple estimation of the strong coupling scale, a result which shows that the strong coupling problem can be avoided at least for some modes. In conclusion, perturbation behaviors that at first appear problematic may not inevitably lead to a strong coupling problem, as long as the relevant scale is comparable with the cutoff scale $M$ of the applicability of the theory.Comment: 18 page

Research Progress on the Relationship between Polymorphism and SLE of Vitamin D Metabolic Pathway Related Gene

Vitamin D is a class of hormones necessary to maintain normalphysiological activities of the body. A large number of studies have shownthat vitamin D, as a fat-soluble vitamin, is not only related to calcium andphosphorus metabolism, but also closely related to immune regulation,humoral regulation, cell cycle and so on. Systemic Lupus erythema-Tosus(SLE) is a specific autoimmune diffuse connective tissue disease thatcauses tissue and organ damage under the joint action of multiple factorssuch as environment and heredity. Among many factors, the vitamin Dmetabolism pathway gene is particularly important for its influence. Someliterature has shown that the genetic polymorphism of vitamin D metabolicpathway genes is correlated with SLE. Therefore, by referring to relevantliterature, this paper summarized the progress in the research on themechanism of genetic polymorphism of vitamin metabolism pathway genesand the development of SLE

Extending the wavelength tunability from 2.01 to 2.1 μm and simultaneous dual-wavelength operation at 2.05 and 2.3 μm in diode-pumped Tm:YLF lasers

Abstract(#br)We report on wavelength extension of diode-pumped Tm:YLF crystal lasers. Using specifically coated end-face mirrors, we have achieved a simulataneous dual-wavelength laser at 2.05 and 2.3 μm with a maximum output power up to 1.33 W and slope efficiency of about 9.7% in continuous-wave regime, for the first time to the best of our knowledge. Moreover, using an un-doped YAG etalon for wavelength tuning, the 2.05 μm lasing wavelength can be shifted to as far as 2.1 μm. We believe that it is the first time that a Tm:YLF laser has been wavelength extended to that far. Using a Cr:ZnSe saturable absorber, a passively Q-switched Tm:YLF laser at 2.05 μm has also attained with a maximum average output power of 0.66 W. The shortest pulse width is 91.7 ns at pulse repetition rate of 8.47 kHz. This work has extended the operating wavelengths of Tm 3+ lasers to that in general for Ho 3+ lasers, which could be practically meaningful for various applications

Testing the ALP-photon coupling with polarization measurements of Sagittarius A*

Ultra-light bosons such as axions or axion-like particles (ALPs), are promising candidates to solve the dark matter problem. A unique way to detect such ALPs is to search for the periodic oscillation feature of the position angles of linearly polarized photons emitted from the regions where ALP dark matter forms a solitonic core. In this work, we use the high-resolution polarimetric measurements of the radiation near the super-massive black hole (SMBH) in the center of the Milky Way, i.e., Sagittarius A$^\star$ (Sgr A$^\star$), by a sub-array of the Event Horizon Telescope to search for the ultra-light ALPs. We derive upper limits on the ALP-photon coupling of $\sim 10^{-12}{\rm GeV^{-1}}$ for ALP masses of $m\sim (10^{-19}-10^{-18})$eV. Our results are stronger than that derived from the observations of SN1987A and a population of supernovae in the mass window of ($10^{-19}-10^{-17}$)eV. Improved polarimetric measurements with the full Event Horizon Telescope can further strengthen the constraints.Comment: Accepted for publication in JCAP. 13 pages, 2 figure

The Anyang Esophageal Cancer Cohort Study: Study Design, Implementation of Fieldwork, and Use of Computer-Aided Survey System

Background: Human papillomavirus (HPV) has been observed repeatedly in esophageal squamous cell carcinoma (ESCC) tissues. However, the causal relationship between HPV infection and the onset of ESCC remains unknown. A large cohort study focusing on this topic is being carried out in rural Anyang, China. Methodology/Principal Findings: The Anyang Esophageal Cancer Cohort Study (AECCS) is a population-based prospective endoscopic cohort study designed to investigate the association of HPV infection and ESCC. This paper provides information regarding the design and implementation of this study. In particular we describe the recruitment strategies and quality control procedures which have been put into place, and the custom designed computer-aided survey system (CASS) used for this project. This system integrates barcode technology and unique identification numbers, and has been developed to facilitate real-time data management throughout the workflow using a wireless local area network. A total of 8,112 (75.3%) of invited subjects participated in the baseline endoscopic examination; of those invited two years later to take part in the first cycle of follow-up, 91.9 % have complied. Conclusions/Significance: The AECCS study has high potential for evaluating the causal relationship between HPV infection and the occurrence of ESCC. The experience in setting up the AECCS may be beneficial for others planning to initiate simila

Patient-derived organoids as a platform for drug screening in metastatic colorectal cancer

Introduction: Most advanced colorectal cancers are aggressive, and there is a lack of effective methods for selecting appropriate anticancer regimens. Patient-derived organoids (PDOs) have emerged as preclinical platforms for modeling clinical responses to cancer therapy.Methods: In this study, we successfully constructed a living biobank with 42 organoids derived from primary and metastatic lesions of metastatic colorectal cancer patients. Tumor tissue was obtained from patients undergoing surgical resection of the primary or metastatic lesion and then used to establish PDOs. Immunohistochemistry (IHC) and drug sensitivity assays were performed to analyze the properties of these organoids.Results: The mCRC organoids were successfully established with an 80% success rate. The PDOs maintained the genetic and phenotypic heterogeneity of their parental tumors. The IC50 values of5-fluorouracil (5-FU), oxaliplatin, and irinotecan (CPT11) were determined for mCRC organoids using drug sensitivity assays. The in vitro chemosensitivity data revealed the potential value of PDOs for clinical applications in predicting chemotherapy response and clinical outcomes in mCRC patients.Discussion: In summary, the PDO model is an effective platform for in vitro assessment of patient-specific drug sensitivity, which can guide personalized treatment decisions for patients with end-stage CRC

Non-enzymatic oxalic acid sensor using platinum nanoparticles modified on graphene nanosheets

Japan Society for the Promotion of Science (JSPS); National Natural Science Foundation of China (NSFC) [21175112]; Science and Technology Planning Project of Fujian Province, China [2012Y0052]An enzyme-free oxalic acid (OA) electrochemical sensor was assembled using a platinum nanoparticle-loaded graphene nanosheets (PtNPGNs)-modified electrode. The PtNPGNs, with a high yield of PtNPs dispersed on the graphene nanosheets, were successfully achieved by a green, rapid, one-step and template-free method. The resulting PtNPGNs were characterized by transmission electron microscopy (TEM), high-resolution TEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and an X-ray diffraction technique. Electrochemical oxidation of OA on the PtNPGNs-modified electrode was investigated by cyclic voltammetry and differential pulse voltammetry methods. Based on the results, the modified electrode exhibited high electrochemical activity with well-defined peaks of OA oxidation and a notably decreased overpotential compared to the bare or even the GNs-modified electrode. Under optimized conditions, a good linear response was observed for the concentration of OA and its current response was in the range of 0.1-15 mM and 15-50 mM with a detection limit (S/N = 3) of 10 mM. Furthermore, the electrochemical sensor presented good characteristics in terms of stability and reproducibility, promising the applicability of the sensor in practical analysis