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The focal plane camera is the core component of the Wide Field-of-view Cherenkov/fluorescence Telescope Array (WFCTA) of the Large High-Altitude Air Shower Observatory (LHAASO). Because of the capability of working under moonlight without aging, silicon photomultipliers (SiPM) have been proven to be not only an alternative but also an improvement to conventional photomultiplier tubes (PMT) in this application. Eighteen SiPM-based cameras with square light funnels have been built for WFCTA. The telescopes have collected more than 100 million cosmic ray events and preliminary results indicate that these cameras are capable of working under moonlight. The characteristics of the light funnels and SiPMs pose challenges (e.g. dynamic range, dark count rate, assembly techniques). In this paper, we present the design features, manufacturing techniques and performances of these cameras. Finally, the test facilities, the test methods and results of SiPMs in the cameras are reported here., Comment: 45 pages, 21 figures, article

The LHAASO-WFCTA experiment, which aims to observe cosmic rays in the sub-EeV range using the fluorescence technique, uses a new generation of high-performance telescopes. To ensure that the experiment has excellent detection capability associated with the measurement of the energy spectrum, the primary composition of cosmic rays, and so on, an accurate geometrical reconstruction of air-shower events is fundamental. This paper describes the development and testing of geometrical reconstruction for stereo viewed events using the WFCTA (Wide Field of view Cherenkov/Fluorescence Telescope Array) detectors. Two approaches, which take full advantage of the WFCTA detectors, are investigated. One is the stereo-angular method, which uses the pointing of triggered SiPMs in the shower trajectory, and the other is the stereo-timing method, which uses the triggering time of the fired SiPMs. The results show that both methods have good geometrical resolution; the resolution of the stereo-timing method is slightly better than the stereo-angular method because the resolution of the latter is slightly limited by the shower track length.

This study compared the efficacy between external fixator combined with palmar T-plate internal fixation and simple plate internal fixation for the treatment of comminuted distal radius fractures. A total of 61 patients classified as type C according to the AO/ASIF classification underwent surgery for comminuted distal radius fractures. There were 54 and 7 cases of closed and open fractures, respectively. Moreover, 19 patients received an external fixator combined with T-plate internal fixation, and 42 received simple plate internal fixation. All patients were treated successfully during 12-month postoperative follow-up. The follow-up results show that the palmar flexion and dorsiflexion of the wrist, radial height, and palmar angle were significantly better in those treated with the external fixator combined with T-plate compared to those treated with the simple plate only (P0.05); however, there were no significant differences in radial-ulnar deviation, wrist range of motion, or wrist function score between groups (P0.05). Hence, the effectiveness of external fixator combined with T-plate internal fixation for the treatment of comminuted distal radius fractures was satisfactory. Patients sufficiently recovered wrist, forearm, and hand function. In conclusion, compared to the simple T-plate, the external fixator combined with T-plate internal fixation can reduce the possibility of the postoperative re-shifting of broken bones and keep the distraction of fractures to maintain radial height and prevent radial shortening.

Introduction Open reduction and internal fixation of distal radius fractures often necessitates release of the brachioradialis from the radial styloid. However, whether this common procedure makes the reduction and fixation easier and affects the elbow function has not been fully understood. Hypothesis Brachioradialis (BR) release during volar plate fixation for type C distal radius fractures makes internal reduction and fixation easier, and it does not adversely affect wrist or elbow function. Material and methods A total of 74 patients treated with 2.4 mm volar locking compression column plate (VCP) were analyzed for type C distal radius fractures prospectively. The patients were divided into two groups, group A with BR release and group B without BR release. The two groups were compared in terms of “internal reduction and fixation time” during the operation, wrist and elbow function including the scores of Gartland and Werley (G-W), Patient-Related Wrist Evaluation Score (PRWE), Mayo Elbow Performance Score (MEPS), the Disabilities of the Arm, Shoulder, and Hand (DASH) and a visual analogue scale (VAS) for pain at 6 and 12 months postoperatively. The radial inclination angle, palmar tilt angle and ulnar variance were also measured from the radiographs. Results According to the follow-up of the 74 patients, no significant differences were observed between the two groups on MEPS, DASH, G-W, PRWE, VAS and radiological outcomes at 6 and 12 months postoperatively. Mean time of reduction and internal fixation was significantly shorter in group A than that in group B. Conclusion Release of the BR for type C distal radius fractures facilitated the surgical procedure and did not adversely affect elbow and wrist function. Level of evidence II, prospective comparative study.

Being a kind of framework material, framework interstice concrete is composed of single-grade or gap-grade aggregate which are bonded by cement or bitumen, whose structural characteristic is “bonding crunode + aggregate + space”. This paper develops a kind of micromechanical model, carrying out numerical simulation of flexual performance of the framework interstice concrete. The calculating results basically conform to the experimental result gained in the laboratory. The method discussed in the paper can be developed to apply in calculating analysis on all kinds of framework interstice concrete materials.