Photometric Variability in the CSTAR Field: Results From the 2008 Data Set

The Chinese Small Telescope ARray (CSTAR) is the first telescope facility built at Dome A, Antarctica. During the 2008 observing season, the installation provided long-baseline and high-cadence photometric observations in the i-band for 18,145 targets within 20 deg2 CSTAR field around the South Celestial Pole for the purpose of monitoring the astronomical observing quality of Dome A and detecting various types of photometric variability. Using sensitive and robust detection methods, we discover 274 potential variables from this data set, 83 of which are new discoveries. We characterize most of them, providing the periods, amplitudes and classes of variability. The catalog of all these variables is presented along with the discussion of their statistical properties.Comment: 38 pages, 11 figures, 4 tables; Accepted for publication in ApJ

Photometry of Variable Stars from Dome A, Antarctica

Dome A on the Antarctic plateau is likely one of the best observing sites on Earth thanks to the excellent atmospheric conditions present at the site during the long polar winter night. We present high-cadence time-series aperture photometry of 10,000 stars with i<14.5 mag located in a 23 square-degree region centered on the south celestial pole. The photometry was obtained with one of the CSTAR telescopes during 128 days of the 2008 Antarctic winter. We used this photometric data set to derive site statistics for Dome A and to search for variable stars. Thanks to the nearly-uninterrupted synoptic coverage, we find 6 times as many variables as previous surveys with similar magnitude limits. We detected 157 variable stars, of which 55% are unclassified, 27% are likely binaries and 17% are likely pulsating stars. The latter category includes delta Scuti, gamma Doradus and RR Lyrae variables. One variable may be a transiting exoplanet.Comment: Accepted for publication in the Astronomical Journal. PDF version with high-resolution figures available at http://faculty.physics.tamu.edu/lmacri/papers/wang11.pd

Eclipsing Binaries From the CSTAR Project at Dome A, Antarctica

The Chinese Small Telescope ARray (CSTAR) has observed an area around the Celestial South Pole at Dome A since 2008. About $20,000$ light curves in the i band were obtained lasting from March to July, 2008. The photometric precision achieves about 4 mmag at i = 7.5 and 20 mmag at i = 12 within a 30 s exposure time. These light curves are analyzed using Lomb--Scargle, Phase Dispersion Minimization, and Box Least Squares methods to search for periodic signals. False positives may appear as a variable signature caused by contaminating stars and the observation mode of CSTAR. Therefore the period and position of each variable candidate are checked to eliminate false positives. Eclipsing binaries are removed by visual inspection, frequency spectrum analysis and locally linear embedding technique. We identify 53 eclipsing binaries in the field of view of CSTAR, containing 24 detached binaries, 8 semi-detached binaries, 18 contact binaries, and 3 ellipsoidal variables. To derive the parameters of these binaries, we use the Eclipsing Binaries via Artificial Intelligence (EBAI) method. The primary and the secondary eclipse timing variations (ETVs) for semi-detached and contact systems are analyzed. Correlated primary and secondary ETVs confirmed by false alarm tests may indicate an unseen perturbing companion. Through ETV analysis, we identify two triple systems (CSTAR J084612.64-883342.9 and CSTAR J220502.55-895206.7). The orbital parameters of the third body in CSTAR J220502.55-895206.7 are derived using a simple dynamical model.Comment: 41 pages, 12 figures; published online in ApJ

PHOTOMETRY OF VARIABLE STARS FROM DOME A, ANTARCTICA: RESULTS FROM THE 2010 OBSERVING SEASON

We present results from a season of observations with the Chinese Small Telescope ARray (CSTAR), obtained over 183 days of the 2010 Antarctic winter. We carried out high-cadence time-series aperture photometry of 20,000 stars with i<15.3 mag located in a 23 square-degree region centered on the south celestial pole. We identified 188 variable stars, including 67 new objects relative to our 2008 observations, thanks to broader synoptic coverage, a deeper magnitude limit and a larger field of view. We used the photometric data set to derive site statistics from Dome A. Based on two years of observations, we find that extinction due to clouds at this site is less than 0.1 and 0.4 mag during 45% and 75% of the dark time, respectively.Comment: Accepted for publication in the Astronomical Journal. Light curves and finding charts of all variable stars will be made available at http://casdc.china-vo.org/data/csta

Homozygous mutation in DNAAF4 causes primary ciliary dyskinesia in a Chinese family

Primary ciliary dyskinesia (PCD) is a rare autosomal recessive disorder that affects the structure and function of motile cilia, leading to classic clinical phenotypes, such as situs inversus, chronic sinusitis, bronchiectasis, repeated pneumonia and infertility. In this study, we diagnosed a female patient with PCD who was born in a consanguineous family through classic clinical manifestations, transmission electron microscopy and immunofluorescence staining. A novel DNAAF4 variant NM_130810: c.1118G&gt;A (p. G373E) was filtered through Whole-exome sequencing. Subsequently, we explored the effect of the mutation on DNAAF4 protein from three aspects: protein expression, stability and interaction with downstream DNAAF2 protein through a series of experiments, such as transfection of plasmids and Co-immunoprecipitation. Finally, we confirmed that the mutation of DNAAF4 lead to PCD by reducing the stability of DNAAF4 protein, but the expression and function of DNAAF4 protein were not affected

A Novel Free‐hand Technique of Pedicle Screw Placement in the Lumbar Spine: Accuracy Evaluation and Preliminary Clinical Results

Objective Pedicle screw implantation is the most common technique to achieve stability during spinal surgeries. Current methods for locating the entry point do not have a quantified criteria and highly rely on the surgeons' experience. Therefore, we aim to propose a quantified pedicle screw placement technique in the lumbar spine and to investigate its accuracy and safety in clinical practice. Methods We conducted a retrospective study involving 110 patients who received spinal surgery in our hospital from August 2018 to August 2021. All patients included had herniation of a single lumbar disc and were consistently treated with posterior discectomy, inter‐body fusion, and transpedicular internal fixation. For 54 patients in the observation group, the pedicle screws were placed with our technique, which is located at 4 mm below the superior edge of the transverse process in line with the lateral margin of the superior articular process. For 56 patients in the control group, pedicle screws were placed according to the traditional crista lambdoidalis method. Comparisons were made in terms of the operation time, blood loss, time for exposure, the accuracy of placement, and postoperative complications. Furthermore, we applied our method to 64 patients with indistinguishable crista lambdoidalis and evaluated the accuracy of screw placement and clinical outcomes according to the visual analogue scale (VAS) and the Japanese Orthopaedic Association (JOA) score. Results There was no significant difference in intraoperative bleeding, accuracy of placement, and postoperative complications between our technique and the traditional crista lambdoidalis method (P > 0.05). However, the exposure time before screw placement (12.8 ± 0.3 vs. 17.4 ± 0.3, P = 0.001) and the total surgery time (97.2 ± 1.9 vs 102.3 ± 0.9, P = 0.020) were significantly shortened with our method. Additionally, in cases with indistinguishable crista lambdoidalis, our technique showed satisfying accuracy, with 97.6% screws placed in appropriate trajectory on the first attempt and all screws eventually positioned in the safe zone according to the Gertzbein–Robbins grading. All patients experienced steady improvement after surgery. Conclusion Placing pedicle screws at 4 mm below the superior edge of the transverse process in line with the lateral margin of the superior articular process is a viable pedicle screw placement method. With this method, we observed a higher success rate and shorter operation time. In addition, this method can be applied in cases with indistinguishable crista lambdoidalis, and have satisfied success rate and clinical outcome

Rotation Speed Control of the Rotary Valve in MWD Tools Based on Speed Feedforward Compensation

The rotary valve speed control, seriously affected by the nonlinear characteristic of rotary valve load torque, affects the generation of drilling fluid pressure phase shift keying (PSK) signal and its quality. The calculation model feedforward of the load torque acts on the speed control system and enables the motor voltage to change according to the law of calculation model, and the linearization correction of the speed system is performed. Additionally, the flow measurement is introduced into the calculation model of the load torque to track the load torque change with the flow, suppressing the influence of large changes in flow rate on open-loop control of rotary valve speed. The closed-loop proportional-integral-derivative (PID) control is formed by negative feedback of speed, and the PID parameter value rule is established based on the rapid decay control of transient component in the rotary valve speed step response, which speeds up the tracking of the rotary valve speed following the control voltage pulse and reduces the distortion of the drilling fluid pressure PSK signal, increasing the frequency of the drilling fluid pressure carrier and improving the transmission rate of downhole information. Simulink simulation indicates that the closed-loop PID control of rotary valve speed can track the change of control voltage pulse quickly and strongly suppress the interference influences from flow measurement error and load torque calculation model deviation