The adolescent pattern of sleep spindle development revealed by HD-EEG polisomnography

Sleep spindles are developmentally relevant cortical oscillatory patterns; however, they have mostly been studied by considering the entire spindle frequency range (11 to 15 Hz) without a distinction between the functionally and topographically different slow and fast spindles, using relatively few electrodes and analysing wide age-ranges. Here, we employ HD-EEG polysomnography in three age-groups between 12 to 20 years of age, with an equal distribution between the two genders, and analyse the adolescent developmental pattern of the four major parameters of slow and fast sleep spindles. Most of our findings corroborate those very few previous studies that also make a distinction between slow and fast spindles in their developmental analysis. We find spindle frequency increasing with age, although spindle density change is not obvious in our study. We confirm the declining tendencies for amplitude and duration, although within narrower, more specific age-windows than previously. Spindle frequency seems to be higher in females in the oldest age-group. Based on the pattern of our findings, we suggest that HD-EEG, specifically targeting slow and fast spindle ranges and relatively narrow age-ranges would advance the understanding of both adolescent development and the functional relevance of sleep spindles in general.

Development of Smart Tooling Concepts Applied to Ultraprecision Machining

This paper presents smart tooling concepts applied to ultraprecision machining, particularly through the development of smart tool holders, two types of smart cutting tools, and a smart spindle for high-speed drilling and precision turning purposes, respectively. The smart cutting tools presented are force-based devices, which allow measuring the cutting force in real-time. By monitoring the cutting force, a suitable sensor feedback signal can be captured, which can then be applied for the smart machining. Furthermore, an overview of recent research projects on smart spindle development is provided, demonstrating that signal feedback is very closely correlated to the drilling through a multilayer composite board. Implementation aspects on the proposed smart cutting tool are also explored in the application of hybrid dissimilar material machining.

Development of Smart Tooling Concepts Applied to Ultra-Precision and High Speed Machining

This paper presents smart tooling concepts applied to ultra-precision and high speed machining, particularly through the development of smart tool holders, two types of smart cutting tools and a smart spindle for high speed drilling and precision turning purposes respectively. The smart cutting tools presented are force-based devices, which allow measuring the cutting force in real time. By monitoring the cutting force a suitable sensor feedback signal can be captured, which can then be applied for the smart machining. Furthermore, an overview of recent research projects on smart spindle development is provided, demonstrating that signal feedback is very closely correlated to the drilling through a multilayer composite board. Implementation aspects on the proposed smart cutting tool are also explored in the application of hybrid dissimilar material machining.

Time course of meiotic spindle development in MII oocytes

SummaryThe aim of this study was to examine changes in meiotic spindle morphology over time to potentially optimize timing for ICSI. Using polarized light microscopy, images of MII oocytes were captured after retrieval of oocytes in stimulated cycles at six time intervals in culture: 36–36.5 h, 36.5–37.0 h, 38–38.5 h, 39–39.5 h, 40–40.5 h and 40.5–41 h post hCG. Captured images were analysed for spindle presence and their retardance. Results showed that spindles were detected in 58% (45/78) of oocytes at 36–36.5 h. This percentage rose to a peak (96% vs. 58%, p < 0.001) at 39–39.5 h and stabilized between 39–40.5 h post trigger then significantly declined at 40.5–41 h post hCG (96% vs. 77%, p < 0.001). Average spindle retardance increased from 36–36.5 h (1.8 ± 0.7 nm) until it peaked at 39–40.5 h (3.8 ± 0.8 nm, p < 0.0001) and then declined significantly after 40.5–41 h (3.2 ± 0.9 nm, p = 0.0001). These results show that the meiotic spindle appearance is time dependent with the majority of oocytes having detectable spindles and highest retardance between 39–40.5 h post hCG under currently used stimulation protocol after which they start to disaggregate. 39–40.5 h post hCG may be the optimal time for ICSI.