363 research outputs found

    Active decoupling of RF coils using a transmit array system

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    Objective: Implementation of a decoupling method for isolation of transmit and receive radio frequency (RF) coils for concurrent excitation and acquisition (CEA) MRI in samples with ultra-short T2*. Materials and methods: The new phase and amplitude (PA) decoupling method is implemented in a clinical 3T-MRI system equipped with a parallel transmit array system. For RF excitation, two transmit coils are used in combination with a single receive coil. The transmit coil is geometrically decoupled from the receive coil, and the remaining B1-induced voltages in the receive coil during CEA are minimized by the second transmit coil using a careful adjustment of the phase and amplitude settings in this coil. Isolation of the decoupling scheme and transmit noise behavior are analyzed for different loading conditions, and a CEA MRI experiment is performed in a rubber phantom with sub-millisecond T2* and in an ex vivo animal. Results: Geometrical (20 dB) and PA decoupling (50 dB) provided a total isolation of 70 dB between the transmit and receive coils. Integration of a low-noise RF amplifier was necessary to minimize RF transmit noise. CEA MR images could be reconstructed from a rubber phantom and an ex vivo animal. Conclusion: CEA MRI can be implemented in clinical MRI systems using active decoupling with parallel transmit array capabilities with minor hardware modifications. © 2015, ESMRMB

    Retrospective analysis of injury trends in recreational skiers and snowboarders in Erciyes Ski Centre

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    Purpose: The purpose of this study is to investigate the important differences in overall rates and frequency of injury cases and injury characteristics between the recreational alpine skiers and snowboarders in Erciyes Ski Centre. Methods: The data for this research was obtained from the Erciyes Ski Centre Injury Surveillance System. A total of 834 injury cases that ski patrols registered injury cases caused by recreational alpine skiing and snowboarding during the 2002 to 2017 winter seasons were respectively examined. The injury cases were grouped according to the skiing disciplines. All data were analysed using SPSS software. Results: Injury cases were 690 skiers (82.7%) and 144 snowboarders (17.3%). 397 (57.5%) male and 293 (42.5%) female were skiers and 91 (63.2%) male and 53 (36.8%) female were snowboarders. There was no statistically significant difference between the gender ratios in skiers and snowboarders (p > .05). Data analysis indicated that there were statistically significant differences in the ratios of lower and upper extremity injuries between skiers and snowboarders ( p < .05 ). Skiers suffered more lower extremity injuries while snowboarders suffered more upper extremity injuries ( p < .05 ). Contusion was the most common injuries type in both skiers and snowboarders ( p < .05) . Conclusions: The lower extremity injuries in skiers and the upper extremity injuries in snowboarders were more common with respect to body location of injuries. For both the recreational activities, contusion was the most common injury type

    The effects of a sleep/recovery supplement: 'Night Time Recharge' on sleep parameters in young adults.

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    BACKGROUND: Concentrated cherry juice reportedly contains melatonin which, in turn, has been highlighted as an important regulator in initiating sleep. AIM: The present investigation aims to clarify whether Night Time Recharge (NTR), a marketed sleep aid containing cherry extract, improves key sleep parameters in young, active adults with mildly poor sleep. METHODS: A double-blind, randomized, placebo-controlled, cross-over study design was employed. Twenty participants (nine female) consumed either NTR or a placebo for seven days. Accelerometers were used to assess sleep quality and physical activity levels. Urinary levels of 6-sulphatoxymelatonin (6-SMT), a marker of melatonin synthesis, was assessed via enzyme-linked immunosorbent assay. RESULTS: 6-SMT levels increased following NTR treatment (28.95 ng/ml) compared with placebo (4.0 ng/ml) (p < 0.001). There was also a significant difference (p = 0.047) in dietary tryptophan consumption during the NTR treatment (1236 mg) versus placebo (1149 mg). No trace of melatonin was detected from our analysis of the supplement. NTR had no significant effect on any sleep parameters with the exception of sleep latency (p = 0.001). CONCLUSIONS: As chemical analysis of NTR by liquid-chromatography mass-spectrometry identified no detectable melatonin, the tryptophan content of the supplement is a likely reason for improvement in sleep latency. These results are in contrast to previous studies which have found a positive effect on sleep following cherry supplementation. Future work should focus on sleep latency and investigating whether cherry juice is effective in participants with problems in initiating sleep

    Cooperation Between Multiple Newsvendors with Warehouses

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