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The surface accuracy of the reflector antenna directly affects the antenna efficiency, and is one of the key performance indicators of the telescopes. Near-field radio holography, which features the advantages of high measurement accuracy and convenience, is one of the most commonly used surface alignment methods for millimeter and submillimeter wave radio telescopes. Near-field radio holography under Cassegrain mode can measure the overall deformation error in the optical path of the telescope. The slant-axis mount is more adaptable to the extreme site environment of terahertz telescopes, and can provide better thermal protection and control for the overall telescope. However, the unique rotation characteristics of the slant-axis antennas will introduce additional error factors during the holography measurements, and devoted study on the near-field holography of slant-axis terahertz under Cassegrain mode has not been reported. In this paper, the influence of the reference receiver position and diffraction of the secondary mirror has been analyzed. The near-field holography measurements have been conducted on a 1.2 m slant-axis terahertz antenna. The repeatability of the experimental system has been evaluated to be better than 2.0 μ m RMS (Root Mean Square), and the comparison between near-field holography and photography has been performed to verify the correctness of the error analyses and corrections. [ABSTRACT FROM AUTHOR]

Purpose: Chemotherapy has been the primary treatment for patients with B-cell acute lymphoblastic leukemia (B-ALL). However, there are still patients who are not sensitive to chemotherapy, including those with refractory/relapse (R/R) disease and those experiencing minimal residual disease (MRD) re-emergence. Chimeric antigen receptor-T lymphocytes (CAR-T) therapy may provide a new treatment option for these patients. Materials and Methods: Our institution conducted a single-arm prospective clinical trial (ChiCTR-OPN-17013507) using CAR-T-19 to treat R/R B-ALL and MRD re-emergent patients. One hundred and fifteen patients, aged 1-25 years (median age, 8 years), were enrolled, including 67 R/R and 48 MRD re-emergent CD19-positive B-ALL patients. Results: All patients achieved morphologic complete remission (CR), and within 1 month after infusion, 111 out of 115 (96.5%) patients achieved MRD-negative CR. With a median follow-up time of 48.4 months, the estimated 4-year leukemia-free survival (LFS) rate and overall survival (OS) rate were 68.7%±4.5% and 70.7%±4.3%, respectively. There were no significant differences in longterm efficacy observed among patients with different disease statuses before infusion (4-year OS: MRD re-emergence vs. R/R B-ALL, 70.6%±6.6% vs. 66.5%±6.1%, p=0.755; 4-year LFS: MRD re-emergence vs. R/R B-ALL, 67.3%±7.0% vs. 63.8%±6.2%, p=0.704). R/R B-ALL patients bridging to transplantation after CAR-T treatment had a superior OS and LFS compared to those who did not. However, for MRD re-emergent patients, there was no significant difference in OS and LFS, regardless of whether they underwent hematopoietic stem cell transplantation or not. Conclusion CD19 CAR-T therapy effectively and safely cures both R/R B-ALL and MRD re-emergent patients. [ABSTRACT FROM AUTHOR]

Abstract Pointing calibration and sub-reflector focusing are an important task of antenna measurement, which significantly contributes to the observational performance of a radio telescope. According to the requirements on the pointing accuracy and defocusing gain loss of the 5 m Dome A Terahertz Explorer (DATE5), this paper has derived the requirements of signal-to-noise ratio for the pointing and sub-reflector focusing calibration observations, and selected several astronomical radio sources suitable for the pointing and focusing calibrations at the terahertz waveband in Antarctica, which include planets and ultra-compact HII regions. The effects of the atmospheric absorption and the source angular diameter on the accuracy of calibration measurements are analyzed. Simulations show that when the telescope operates in Antarctica, these sources can provide sufficient flux densities for verifying the pre-established pointing model and focusing model. [ABSTRACT FROM AUTHOR]

The slant-axis telescope has a novel structure, and its unique structural design is more suitable for extreme environment such as the South Pole. However, there is a lack of research on the dynamic modeling and the controller design of slant-axis telescopes at home and abroad. This paper proposes a dynamic modeling and robust control method for slant-axis telescope. Firstly, the dynamical analysis of the slant-axis telescope is carried out. The 2-degree-of-freedom rigid body model of the telescope is established by the Lagrange method. Next, combining the flexibility of the driver system and disturbance, a mathematical model of the rigid-flexible coupling system of the slant-axis telescope is completed. Then, according to the established mathematical model, a sliding mode controller based on the disturbance observer is designed to suppress the disturbance, and realize the robust control of the slant-axis telescope. Finally, the simulation results show that the disturbance observer based sliding mode controller gets better dynamic performance and anti-disturbance characteristics than the traditional Proportion-Integration-Differentiation (PID) controller in the case of considering nonlinear external interference of the model. [ABSTRACT FROM AUTHOR]

Due to its unique rotation mechanism, a slant-axis mount provides a better adaptability for the extreme site conditions, such as those in Antarctica, compared to traditional equatorial and altazimuth mounts. However, the study devoted to the motion characteristics of slant-axis mount has not been reported yet. In this paper, the advantages and disadvantages of the slant-axis mount are first discussed. The transformation relations between the slant-axis coordinate system and the horizontal and equatorial coordinate systems are then derived, based on this the motion characteristics of slant-axis mount during a normal sidereal tracking are studied, and compared with those of altazimuth mounts. The image rotation behavior of slant-axis mount is also studied, and its influence on the reflector holographic measurement is analyzed. Finally, a pointing model including seven error terms and suitable for slant-axis telescopes is derived. [ABSTRACT FROM AUTHOR]

In view of the scarcity of terahertz astronomical point source targets, this paper studies the method of using a small optical telescope coaxial with terahertz antenna to assist the pointing measurement of terahertz telescope and establish the pointing error correction model. Based on the 1.2 m oblique axis terahertz antenna of Purple Mountain Observatory, the experiment of optical aided pointing measurement is carried out. A 100 mm aperture refractive optical telescope mounted on the antenna back frame is used to obtain the pointing measurement accuracy better than 2 ″. In addition, by analyzing the structure of the slant axis antenna and the error sources of atmospheric refraction and local star time deviation, a slant axis optical pointing correction model with 23 error terms is established, and the fitting accuracy of about 3 ″ is achieved. Finally, with the help of high-precision digital photogrammetry, the photoelectric axis consistency is calibrated, and its influence on the pointing model accuracy is discussed. The research results of this paper will provide technical reference for the 5 m Dome A Terahertz Explorer (DATE5) and other terahertz telescopes in pointing measurement and correction. [ABSTRACT FROM AUTHOR]

Delingha 13.7 m telescope is one of the most important radio telescopes in China. Since installing the superconducting spectroscopic array receiver (SSAR) and adopting the On The Fly (OTF) observation mode, the telescope has operated for nearly 10 years. During this period, a large number of astronomical observation projects have been carried out and completed, a large amount of astronomical data have been accumulated, and a series of important scientific results have been achieved. This paper introduces the operating status of SSAR in astronomical observations, the problems in operations, as well as the fault phenomena and solutions. The performance test and performance analysis of SSAR are described in detail, including the receiver noise temperature and telescope system noise temperature, image rejection ratio (IRR), receiver stability, beam performance and so on. The updating and development of SSAR are listed, including the automatic adjustment of LO (Local Oscillator) power, the updating of pre-amplification circuits of the sideband separation superconducting mixer, and the optimization of control program, etc. This paper summarizes the experiences and rules, and connects the past with the future, for applying the experiences of the maintenance and operation of SSAR to the next-generation large-scale receiver system. [ABSTRACT FROM AUTHOR]

The Superconducting Superconductor-Insulator-Superconductor (SIS) receivers have become the preferred method for (sub)millimeter-wave radio astronomical observations due to the extremely low receiver noise temperature. The coupling noise of the local oscillator (LO) system is also a part of the receiver noise. In many years of astronomical observations, it is found that the LO-coupled noise cannot be completely ignored, which has a certain impact on the sensitivity of astronomical observations. The noise temperature of the superconducting SIS receiver was tested using two different kinds of signal generators as the primary signal source of the LO system. It is found that the base noise output by the signal generator can be coupled into the receiver to increase the receiver noise. By adding a narrow band filter to the output of the signal generator, the base noise of the signal generator can be filtered out, and this part noise of the receiver can be eliminated, the overall noise of the receiver is reduced, and the sensitivity of the telescope is improved. [ABSTRACT FROM AUTHOR]

In astronomical observations, the radio frequency interference (RFI) will cause pseudo spectra and reduce the reliability and validity of observational data. The RFI mitigation, which includes many technical innovations of devices and the method studies of data processing, aims at reducing the influence of RFI on the radio astronomical observation. Various efforts were made to improve the anti-RFI capability of the multi-beam receiver (Superconducting Spectroscopic Array Receiver, SSAR) of the Delingha 13.7 m telescope. The interference transmission path was analyzed. The concepts of the device RFI direct coupling coefficient and the device RFI system coupling coefficient were proposed. The proportions of interference introduced in the receiver system by the different devices were quantified, and the interference-susceptible devices in the system were located. After the anti-RFI treatment of the interference-susceptible devices, the anti-RFI capability of the receiver system is improved by 30 dB in average, and the astronomical observation efficiency of the telescope is increased by more than 10%. [ABSTRACT FROM AUTHOR]

Limited by the working temperature of the test equipment, most of high-precision surface figure measurement techniques cannot be put into application under a cryogenic environment. This paper reports the first attempt to measure the surface figure of a high-precision terahertz reflector panel under low temperatures based on photogrammetry. The measurement employs a high-resolution industrial camera sitting on the automatic testing platform which enables photos been taken in an automatic fashion inside a climate chamber. A repeatable accuracy of 2.1 μ m (rms) is achieved under the cryogenic environment. Furthermore, the surface figure measured by a three-coordinate measuring machine under the room temperature is used to calibrate the thickness differences of the targets. By this technique, the surface figure of an aluminum prototype panel of the 5 meter Dome A Terahertz Telescope (DATE5) is measured from room temperature down to −55°C to obtain the rule of variation of surface deformation of the panel under low temperatures. [ABSTRACT FROM AUTHOR]