An investigation of thin film magnetic recording media

Mechanical, physical and chemical changes in the surface of commercial thin film metal evaporated magnetic recording media have been correlated to recording error and signal degradation measurements. Modified and adapted commercial Hi-8 video recorders have been used for sample generation whilst analytical techniques such as SXPS,IMS and SEM have been employed in the surface characterisation. The durability of the media was assessed through stop motion (still frame) and cycling tests, where error growth and signal degradation were measured as a function of running time. The tests were performed under ambient (22°C, 40% RH) and high humidity (22°C, 80% RH) conditions. Characterisation of the lubricant layer on each tape was performed through models based on XPS and angle resolved XPS. The lubricant thickness can significantly affect the durability and signal output level of a thin film tape and thus it is important that reliable quantification can be achieved. Various models were considered for determining the lubricant thickness although ultimately, the most suitable technique was deemed to be a model that assumed a uniform layer structure. In addition to thin film metal evaporated media, equivalent durability tests and surface analysis experiments were performed using a commercial metal particle tape in order that comparisons could be made between the two types of recording media. The signal performance of the thin film metal evaporated media was found to be quite different from that for the metal particle tape since dropout errors and signal degradation increased at a much earlier stage. Extensive surface analyses enabled the mechanisms responsible for media failure and error growth to be identified in the ME and MP tapes and these were found to result from cyclic stressing and fatigue on the immediate substrate of the media

Trophoblast organoids as a model for maternal-fetal interactions during human placentation.

The placenta is the extraembryonic organ that supports the fetus during intrauterine life. Although placental dysfunction results in major disorders of pregnancy with immediate and lifelong consequences for the mother and child, our knowledge of the human placenta is limited owing to a lack of functional experimental models1. After implantation, the trophectoderm of the blastocyst rapidly proliferates and generates the trophoblast, the unique cell type of the placenta. In vivo, proliferative villous cytotrophoblast cells differentiate into two main sub-populations: syncytiotrophoblast, the multinucleated epithelium of the villi responsible for nutrient exchange and hormone production, and extravillous trophoblast cells, which anchor the placenta to the maternal decidua and transform the maternal spiral arteries2. Here we describe the generation of long-term, genetically stable organoid cultures of trophoblast that can differentiate into both syncytiotrophoblast and extravillous trophoblast. We used human leukocyte antigen (HLA) typing to confirm that the organoids were derived from the fetus, and verified their identities against four trophoblast-specific criteria3. The cultures organize into villous-like structures, and we detected the secretion of placental-specific peptides and hormones, including human chorionic gonadotropin (hCG), growth differentiation factor 15 (GDF15) and pregnancy-specific glycoprotein (PSG) by mass spectrometry. The organoids also differentiate into HLA-G+ extravillous trophoblast cells, which vigorously invade in three-dimensional cultures. Analysis of the methylome reveals that the organoids closely resemble normal first trimester placentas. This organoid model will be transformative for studying human placental development and for investigating trophoblast interactions with the local and systemic maternal environment.Centre for Trophoblast Reearch Royal Society Dorothy Hodgkin Fellowship Marie Curie Intra-European Fellowshi

The effects of sound level and vibration magnitude on the relative discomfort of noise and vibration

The relative discomfort caused by noise and vibration, how this depends on the level of noise and the magnitude of vibration, and whether the noise and vibration are presented simultaneously or sequentially has been investigated in a laboratory study with 20 subjects. Noise and vertical vibration were reproduced with all 49 combinations of 7 levels of noise and 7 magnitudes of vibration to allow the discomfort caused by one of the stimuli to be judged relative to the other stimulus using magnitude estimation. In four sessions, subjects judged noise relative to vibration and vibration relative to noise, with both simultaneous and sequential presentations of the stimuli. The equivalence of noise and vibration was not greatly dependent on whether the stimuli were simultaneous or sequential, but highly dependent on whether noise was judged relative to vibration or vibration was judged relative to noise. When judging noise, higher magnitude vibrations appeared to mask the discomfort caused by low levels of noise. When judging vibration, higher level noises appeared to mask the discomfort caused by low magnitudes of vibration. The judgment of vibration discomfort was more influenced by noise than the judgment of noise discomfort was influenced by vibration