Summary The ocean is the primary source of seismic ambient noise. Therefore, seismic recordings at seafloor stations should reveal noise characteristics more directly than land stations. However, due to a lack of broadband seismic instrumentation, seafloor noise studies using seafloor stations have been inadequate compared to land-based instrumentation. In this study, we use seismic data collected at the South China Sea (SCS) seafloor by newly developed Ocean Bottom Seismographs (OBSs) to analyze the ambient noise features in this marginal sea. The broadband OBS, dubbed ‘Pankun’, has unique shielding to isolate its sensor from the influences of bottom currents. A side-by-side land test between the OBS sensor unit and a standalone seismometer showed that the self-noise caused by the gimbal and the pressure case is insignificant. The recordings on the SCS seafloor have distinct noise spectra. The Double Frequency Microseisms (DFMs) have a single instead of double peak like that seen for Pacific stations. The peak appears in a lower period range (1–5 s) than in the global noise model, indicating that the primary source region for the DFM is the SCS itself. The high-frequency content of the DFM is attenuated more as it propagates from its source region (seafloor) to land stations. The Single Frequency Microseism (SFM) peak on the spectrum is weak, reflecting that SFMs, generated in shallow water along the coast, have difficulties propagating back into the deep ocean due to the substantial increase in seafloor depth. A long-period Earth's hum signal is also identifiable on the vertical component at periods greater than 50 s, probably due to the anti-current design of the OBS. Although the seasonal sea state mainly affects the noise level, extreme events such as typhoons can produce short-term abnormally high DFMs in the basin. However, the DFM highs caused by such events exhibit complex patterns, depending on the wind speed, duration, and area covered by the events.

BackgroundSince 1998, China has gradually moved toward voluntary uncompensated blood donation. In some cities, the shortage of platelets has been noticeably severe. Mutual assistance that collects blood from one’s family and social networks is a potential solution. The measure, however, turned out problematic. There are donors who choose to donate platelets over whole blood without compensations, and donate platelets directly to blood banks instead of via the mutual assistance system. This study explores reasons behind their choices qualitatively.MethodsThis report is based on data conducted from January to February 2018; 25 uncompensated regular platelet donors were interviewed. The blood component donation service team in Guangzhou facilitated the data collection process and referred prospectively eligible blood donors to our research team. The interviews took about 30 min to two hours to complete. The qualitative data were analyzed by using the software ATLAS.ti 8.ResultsPlatelet donation takes a much long time than whole blood donation and requires complicated processes. It may also cause discomfort as the other blood components are returned to the body, causing physical and psychological distress due to worries about contamination. Thus, platelet donation tends to involve higher time and psychological costs than whole blood donation. Yet, it has short collection intervals that allows for more frequent donations, and urgency of a severer shortage than whole blood. Hence, regular platelet donors may feel higher significance in platelet donation than whole blood donation, with the belief that more lives would be saved. Some whole blood donors thus switched to become platelet donors. Mutual assistance blood donation was not chosen by the participants for platelet donation, because such donations may exert moral pressure to both the donors and recipients. Furthermore, “acquaintance” has been loosely defined; the system has sometimes been manipulated to become profit-making monetary transactions. It hence failed.ConclusionsThe practice of platelet donation reinforces the understanding that blood donation is a gift giving process performed among strangers. A safe and sustainable voluntary blood supply can only be secured in the absence of monetary transactions and moral pressure.

This article has been peer reviewed and published immediately upon acceptance.It is an open access article, which means that it can be downloaded, printed, and distributed freely, provided the work is properly cited. Articles in "Folia Morphologica" are listed in PubMed.

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Through anatomy, microscope, histopathology, and simulating needle knife operation on specimens, to accumulate the relevant parameters of the A1 pulley of thumb, and to provide an anatomical evidence for the needle knife therapy of stenosing flexor tenosynovitis. A total of 20 fingers were selected from 20 intact adult upper limb specimens, a small amount of emerald green waterproof dye was injected from the needle insertion point, dissected layer by layer, and the A1 pulley and neurovascular bundle were observed. Observe the loosening of the thumb A1 pulley after 5 and 10 times of simulated needle knife cutting on the specimen; observe the relationship between the needle knife entry point and the A1 pulley under the thumb extension and abduction, and the thumb extension neutral position respectively; further observe the histological characteristics, and the relationship between needle entry point and A1 pulley by microscope. ① In general observation, the A1 pulleys of each finger were transverse fibers perpendicular to the flexor tendon, tough in texture, connected with synovial fibers at the proximal end. It is difficult to distinguish, and connected with oblique fibers at the distal end. ② The release rate of the thumb A1 pulley after 5 and 10 times of simulated needle knife cutting on the specimen were (40.46 ± 2.22)% and (63.52 ± 4.49)%, respectively. ③ In the neutral position of the thumb straightening, the needle entry point is 3.06 ± 0.14 mm from the proximal side of the proximal edge of the A1 pulley, which overlaps with the needle entry point where the thumb is straight and abducted. ④ Observed under a microscope, the A1 pulley is a dense transverse fiber with a pale yellow dense connective tissue, both ends are continuous with the synovial fibers. It is thin and translucent, and loose connective tissue. The A1 pulley is a dense transverse fiber with a pale yellow dense connective tissue. The anatomical key points of the needle knife therapy lie in the extended and abducted position of the thumb. Currently, it is believed that cutting the proximal edge of the A1 pulley is sufficient, and there is no need to cut the entire A1 pulley.