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The aim of the study was to verify a hypothesis that critical flicker fusion frequency (CFFF) is season-related because of changes in the intensity and duration of sunlight. CFFF has a wide application in different fields, generally as an indicator of human workload. Therefore, confirmation of previous observations that CFFF is subject to a seasonal rhythm could make theoretical as well as practical sense. The analysis was based on data obtained from 23 male participants, aged 28-60 years. The study lasted 12 months. CFFF was measured with the flicker test. The results of statistical analysis indicate that CFFF changes over time. There are two forms of those changes: a linear trend and oscillations around the trend. Moreover, individual differences in the longitudinal course of CFFF (in trends as well as in oscillations) are observed. The conclusion is that CFFF is subject to longitudinal changes, whose pattern depends on individual differences. Additionally, the individual character of the CFFF changes over time allow the assumption that sunlight is probably not as significant a factor as expected, one that can modify the hypothetical pattern of season-related CFFF fluctuation. The obtained results are important for the methodology of experiments with CFFF and for the interpretation of the results of the flicker test.

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BackgroundCranial cruciate ligament rupture is the most frequent orthopedic disorder in human and animals. An array of surgical techniques have been described to stabilize the stifle joint in dogs, including intraarticular stabilization, extraarticular stabilization, and tibial osteotomy techniques. Tibial plateau leveling osteotomy and tibial tuberosity advancement with a lot of modifications are the most common. In this study we report the possibility of fixing the novel titanium implant for tibial tuberosity advancement with two screws in a craniocaudal direction. The aim of our study was to improve the clinical benefit of the tibial tuberosity advancement surgical technique where an attempt was made to reduce the number of screws and obtain a strong implant fixation with minimal bone traumatization. This way of attachment allows to distribute the forces evenly on medial and lateral side of osteotomy gap.ResultsTibial tuberosity advancement with cranial implant fixation was performed in four sheep. Complete radiographic and clinical follow up was recorded. All four sheep had a complete osteotomy line healing at a mean of 10 weeks postoperative (range 8–12 weeks). None of the animals had osteotomy gap healing grades of poor. Minor complication included the minimally cracked Maquet hole on the postoperative radiographs, without displacement of the tibial crest which occurred in 2 sheep. Major complication grade 1, major complication grade 2 and catastrophic were not found.ConclusionsThe novel surgical technique for tibial tuberosity advancement with cranial implant fixation is technically comparable to the recent trend in tuberosity advancement techniques, where partial osteotomy of the cranial tibial tuberosity crest is performed. A cranial implant fixation allows to distribute the forces evenly on medial and lateral side of osteotomy gap, which may result in less number of major complications in dogs. A novel titanium implant decreases the tibial traumatisation by reducing the number of screws.

This article aims to present the physical adaptation capabilities of a human, seen as a response to extreme hot and dry or hot and humid conditions. Adaptation capabilities are expressed as safe exposure time in two variants: at rest and during physical activity. The study shows the results of calculations of the variability over time of the core temperature and skin temperature as well as heat balance. Calculations were made according to Standard No. EN ISO 7933:2005 on the basis of assumed and actual meteorological data. The results of the calculations show that in these conditions a hot but dry environment enables a human (although to a limited extent) to stay and perform low physical activity, provided access to drinking water is ensured. In contrast, a hot but humid environment causes more serious problems, due to the inability to reduce skin temperature by evaporation of sweat from the skin surface.