HYDRA-TPC Prototype - a Time Projection Chamber for Light Hypernuclei Study at R³B, GSI/FAIR

Hypernuclei offer a unique approach to investigating hyperon-nucleon interactions. However, their extremely short lifetimes, on the order of sub-nanoseconds, pose significant experimental challenges. The HYpernuclei Decay at R³B Apparatus (HYDRA) experiment, designed for operation within the R³B setup at GSI/FAIR, aims to perform heavy-ion collision experiments with the primary objective of performing high-precision invariant mass spectroscopy of light hypernuclei. This thesis presents the development of the HYDRA Time Projection Chamber (TPC) specifically designed for tracking π − produced from hypernuclear decays within the GLAD magnet of the R³B. The TPC incorporates a double-layer wired drift field cage with a drift distance of 300 mm and an active area of 256 × 88 mm2. A hybrid amplification stage was implemented, comprising a Gas Electron Multiplier (GEM) and a Micromegas detector. This configuration is expected to achieve an ion back-flow of less than 1%. The design of the field cage was optimized through two-dimensional simulations employing the finite element method and Monte Carlo techniques to ensure a homogeneous drift field. Electron drift displacement was determined to be less than 250 µm at the edge of the active region and less than 200 µm in the central region of the TPC. The gain performance of the TPC was characterized using an X-ray source. By adjusting the high voltage applied to the electrodes, the influence of varying high voltages in different regions on the overall effective gain of the TPC was quantified. The TPC was successfully commissioned with a front-end readout system incorporating multiplexing boards and digitizing readout electronics based on the GET system. Subsequently, its tracking performance was assessed through measurements of laser tracks generated by a 266-nm ultraviolet laser source and reflected into the drift volume by micromirror bundles, which were integrated within the TPC. A tracking algorithm was developed to reconstruct these laser tracks. Experimental results demonstrated a spatial resolution better than 3 mm in the drift direction, while the pad plane resolution did not meet the desired 200 µm requirement. Finally, the influence of magnetic fields on the drift electron trajectories was investigated within the GLAD magnet at magnetic field strengths ranging from 0 to 0.92 T

A Sliding Mode Control Based Stabilization Method for Directional Rotary Steering Tool-Face

When the directional rotary steering system works in the state of maintaining the tool face angle, the use of PID control mode will lead to a large swing angle of the tool face angle of the directional rotary steering system. In order to reduce the swing amplitude of the tool face angle, based on the PID position control and the angle position error sliding mode control strategy, the exponential synovial control function is established. The simulation results show that the fast and accurate tool face angle tracking is achieved through the closed-loop control of the angle position. The paper provides an implementation method for the research of directional rotary steering system

Method to evidence hypernuclear halos from a two-target interaction cross section measurement

We present a two-target measurement method to determine the interaction cross section of hypernuclei with a target nucleus. The method allows to extract from two independent measurements the production cross section of a given hypernucleus as well as its interaction cross section on a specific target. The latter is then further analyzed to deduce the matter radius of the hypernucleus. The sensitivity of the method has been investigated for the specific case of the lightest hyperhalo candidate hypertriton (Λ³H) produced from ¹²C+¹²C collisions at 1.9 GeV/nucleon. Furthermore, its feasibility is demonstrated by detailed simulations for realistic experimental conditions at GSI/FAIR, using a dedicated HYDRA (HYpernuclei Decay at R³B Apparatus) time-projection chamber prototype. A precision of 15% or better in the interaction cross section can be achieved, allowing an extraction of the unknown Λ³H matter radius and assessing its halo or non-halo character

RETRACTED: vB-ApyS-JF1, the First Trueperella pyogenes Phage, Shows Potential as an Alternative Treatment Strategy for Trueperella pyogenes Infections

Trueperella pyogenes (T. pyogenes) is an important opportunistic animal pathogen that causes huge economic losses to the animal husbandry industry. The emergence of bacterial resistance and the unsatisfactory effect of the vaccine have prompted investigators to explore alternative strategies for controlling T. pyogenes infection. Due to the ability of phages to kill multidrug-resistant bacteria, the use of phage therapy to combat multidrug-resistant bacterial infections has attracted attention. In this study, a T. pyogenes phage, vB-ApyS-JF1 (JF1), was isolated from sewage samples, and its whole genome and biological characteristics were elucidated. Moreover, the protective effect of phage JF1 on a mouse bacteremic model caused by T. pyogenes was studied. JF1 harbors a double-stranded DNA genome with a length of 90,130 bp (30.57% G + C). The genome of JF1 lacked bacterial virulence–, antibiotic resistance– and lysogenesis-related genes. Moreover, the genome sequence of JF1 exhibited low coverage (<6%) with all published phages in the NCBI database, and a phylogenetic analysis of the terminase large subunits and capsid indicated that JF1 was evolutionarily distinct from known phages. In addition, JF1 was stable over a wide range of pH values (3 to 11) and temperatures (4 to 50°C) and exhibited strong lytic activity against T. pyogenes in vitro. In murine experiments, a single intraperitoneal administration of JF1 30 min post-inoculation provided 100% protection for mice against T. pyogenes infection. Compared to the phosphate-buffered saline (PBS) treatment group, JF1 significantly (P < 0.01) reduced the bacterial load in the blood and tissues of infected mice. Meanwhile, treatment with phage JF1 relieved the pathological symptoms observed in each tissue. Furthermore, the levels of the inflammatory cytokines tumour necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin-6 (IL-6) in the blood of infected mice were significantly (P < 0.01) decreased in the phage-treated group. Taken together, these results indicate that phage JF1 demonstrated great potential as an alternative therapeutic treatment against T. pyogenes infection

Three Capsular Polysaccharide Synthesis-Related Glucosyltransferases, GT-1, GT-2 and WcaJ, Are Associated With Virulence and Phage Sensitivity of Klebsiella pneumoniae

Klebsiella pneumoniae (K. pneumoniae) spp. are important nosocomial and community-acquired opportunistic pathogens, which cause various infections. We observed that K. pneumoniae strain K7 abruptly mutates to rough-type phage-resistant phenotype upon treatment with phage GH-K3. In the present study, the rough-type phage-resistant mutant named K7RR showed much lower virulence than K7. Liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis indicated that WcaJ and two undefined glycosyltransferases (GTs)- named GT-1, GT-2- were found to be down-regulated drastically in K7RR as compared to K7 strain. GT-1, GT-2, and wcaJ are all located in the gene cluster of capsular polysaccharide (CPS). Upon deletion, even of single component, of GT-1, GT-2, and wcaJ resulted clearly in significant decline of CPS synthesis with concomitant development of GH-K3 resistance and decline of virulence of K. pneumoniae, indicating that all these three GTs are more likely involved in maintenance of phage sensitivity and bacterial virulence. Additionally, K7RR and GT-deficient strains were found sensitive to endocytosis of macrophages. Mitogen-activated protein kinase (MAPK) signaling pathway of macrophages was significantly activated by K7RR and GT-deficient strains comparing with that of K7. Interestingly, in the presence of macromolecular CPS residues (>250 KD), K7(ΔGT-1) and K7(ΔwcaJ) could still be bounded by GH-K3, though with a modest adsorption efficiency, and showed minor virulence, suggesting that the CPS residues accumulated upon deletion of GT-1 or wcaJ did retain phage binding sites as well maintain mild virulence. In brief, our study defines, for the first time, the potential roles of GT-1, GT-2, and WcaJ in K. pneumoniae in bacterial virulence and generation of rough-type mutation under the pressure of bacteriophage

A Sliding Mode Control Based Stabilization Method for Directional Rotary Steering Tool-Face

When the directional rotary steering system works in the state of maintaining the tool face angle, the use of PID control mode will lead to a large swing angle of the tool face angle of the directional rotary steering system. In order to reduce the swing amplitude of the tool face angle, based on the PID position control and the angle position error sliding mode control strategy, the exponential synovial control function is established. The simulation results show that the fast and accurate tool face angle tracking is achieved through the closed-loop control of the angle position. The paper provides an implementation method for the research of directional rotary steering system

Bfp net: balanced feature pyramid network for small apple detection in complex orchard environment

Despite of significant achievements made in the detection of target fruits, small fruit detection remains a great challenge, especially for immature small green fruits with a few pixels. The closeness of color between the fruit skin and the background greatly increases the difficulty of locating small target fruits in the natural orchard environment. In this paper, we propose a balanced feature pyramid network (BFP Net) for small apple detection. This network can balance information mapped to small apples from two perspectives: multiple-scale fruits on the different layers of FPN and a characteristic of a new extended feature from the output of ResNet50 conv1. Specifically, we design a weight-like feature fusion architecture on the lateral connection and top-down structure to alleviate the small-scale information imbalance on the different layers of FPN. Moreover, a new extended layer from ResNet50 conv1 is embedded into the lowest layer of standard FPN, and a decoupled-aggregated module is devised on this new extended layer of FPN to complement spatial location information and relieve the problem of locating small apple. In addition, a feature Kullback-Leibler distillation loss is introduced to transfer favorable knowledge from the teacher model to the student model. Experimental results show that of our method reaches 47.0%, 42.2%, and 35.6% on the benchmark of the GreenApple, MinneApple, and Pascal VOC, respectively. Overall, our method is not only slightly better than some state-of-the-art methods but also has a good generalization performance