It is well known that silicon photomultipliers (SiPMs) are prone to radiation damage. With the increasing popularity of SiPMs among new spaceborne missions, especially on CubeSats, it is of paramount importance to characterize their performance in space environment. In this work, we report the in-orbit ageing of SiPM arrays, so-called multi-pixel photon counters (MPPCs), using measurements acquired by the GRBAlpha and VZLUSAT-2 CubeSats at low Earth orbit (LEO) spanning over three years, which in duration is unique. GRBAlpha is a 1U CubeSat launched on March 22, 2021, to a 550 km altitude sun-synchronous polar orbit (SSO) carrying on board a gamma-ray detector based on CsI(Tl) scintillator readout by eight MPPCs and regularly detecting gamma-ray transients such as gamma-ray bursts and solar flares in the energy range of ~30-900 keV. VZLUSAT-2 is a 3U CubeSat launched on January 13, 2022 also to a 550 km altitude SSO carrying on board, among other payloads, two gamma-ray detectors similar to the one on GRBAlpha. We have flight-proven the Hamamatsu MPPCs S13360-3050 PE and demonstrated that MPPCs, shielded by 2.5 mm of PbSb alloy, can be used in an LEO environment on a scientific mission lasting beyond three years. This manifests the potential of MPPCs being employed in future satellites.
The clinical features of rheumatoid arthritis (RA) patients with complete remission were studied retrospectively. One hundred ten patients with early RA who were treated for more than 3 years at our hospital were evaluated. Clinical remission according to Pinals' preliminary criteria was noted in 15 patients (14%) during the observation period. Age, joint number with pain or swelling, duration of morning stiffness, and laboratory data except rheumatoid factor at their first visit showed no significant difference between patients with remission and those without remission. Significant differences in clinical findings were observed 2 years after their first visit.
During a seven-year period, 63 total hip replacements were performed in osteoarthritis patients; Seven dislocations occurred. Three hips had one dislocation, while the remaining 4 dislocated more than once. Six dislocations were posterior and one, anterior. Open reduction was done in one, revision was required in 4.The angle and the height of the acetabular component of the roentgenograms were not significant between the control group and the dislocated group. The leg length (mean) in the surgery of the dislocated group was 9.5mm longer than that of the control group (p<0.01).
For the treatment of calcaneal fractures, evaluation of the posterior articular facet is very important. Intra-articular fracture of the calcaneus can be divided into three groups based on Crosby's classification using CAT. We treated type II and III fractures by open reduction through the lateral approach, and we evaluated clinical results and post-operative congruity of the posterior articular facet of the calcaneus using CAT.There were 11 type II fractures operated on, and no type III fractures. Five patients achieved an excellent result and 6 patients a very good result with minor complaints. The posterior articular facet was reduced anatomically in 9 patients. Two fractures retained their pre-operative congruity.Crosby reported that patients with type II or type III fractures were not satisfied with the results by conservative treatment. We recommend that displacement of the posterior articular facet of the calcaneus be evaluated using CAT and type II fractures be treated surgically, rather than conservatively.
Serial radionuclide ventriculography was performed using a newly developed "real-time" system, and left ventricular ejection fraction (LVEF), right ventricular ejection fraction (RVEF), stroke volume (SV), and cardiac output (CO) were measured during graded supine exercise in five patients with mitral stenosis (MS), in five patients with chronic obstructive pulmonary disease (COPD) and in five healthy subjects. Simultaneous pulmonary gas exchange analysis permitted determining the anaerobic threshold, which is the point during incremental exercise when lactate begins to accumulate in the blood. LVEF at the anaerobic threshold was not significantly changed in any patient groups and in healthy subjects, but RVEF at the anaerobic threshold was lower in COPD and MS patients as compared with healthy subjects. In MS, SV during exercise was reduced at the anaerobic threshold, but not in COPD or in healthy subjects. In conclusion, reduced working capacity is related to decreased RVEF in both COPD and MS, but the inhibited increase in CO during exercise is also important for the working capacity in MS.
