Development of Cal Poly\u27s Shock Table

Shock is one of the environmental tests that a spacecraft must pass before being cleared for launch. Shock testing poses a challenging data acquisition issue and careful selection of equipment is crucial to creating a successful shock test facility. Cal Poly’s CubeSat programs can currently perform all environmental testing other than shock themselves, so a quality shock table would be useful. Previous groups of students had developed a shock table, and this paper details the improvement and characterization of that shock table’s behavior. Several adjustable parameters were tested and documented to discover trends in the shock table’s response to an impact from a pendulum hammer. Then a test meant to mimic an actual shock test was performed. The CubeSat program provided a component to be tested and a requirement to be met. The nominal requirement is proprietary and cannot be given here, and additional stipulations included the test data being within a given tolerance band and at least 50% of the test data having a larger magnitude than the nominal requirement. The requirement needed to be met in all three of the component’s axes. The component was mounted to the shock table and acceleration data was collected and analyzed. A successful test was conducted in one axis, which was the result of impacting the large face of the aluminum shock table plate. The tests in the other two axes, conducted with impacts to the side of the aluminum plate, failed to meet the requirement. A finite element model of the table was developed and correlated to the test data. A new way of attaching the test component to the table was developed that would allow for testing in all three axes to be performed with impacts to the large face of the aluminum plate. A dynamic finite element analysis was performed, and the results indicate that this new attachment method should allow the requirement to be met in all three axes. The shock table is currently fully operational and can be used for testing and teaching purposes. With the implementation of the new attachment method, it is believed that the CubeSat program’s requirements can be met as well

The Elements of Making: a Social Practice Perspective for Everyday Creators

In contrast to behavioural approaches that attempt to explain creativity, social practice theories commonly emphasize aspects of the material world that shape and reproduce how people engage with them. How might social practice theory clarify how making affects millions of hobbyist creators – and what makes making matter to them? This article examines the theoretical work tying creativity to social practice. It then reports on a project in which small groups of everyday creators in the United Kingdom (n = 95) gathered in workshops to discuss their experiences and opinions regarding the materials, meanings, and competences of making. A model-making research method instigated peer discussion revealing both individual and shared accounts of practice. The data indicated that participants, regardless of practice, experienced creating as an ongoing performance providing many benefits that promote personal and societal transformation. With our graphic iteration of the elements of making, we assert that the meanings these makers attached to their various do-it-yourself practices were underscored by the materials they worked with and the competences they built in creating

Development of X-43A Mach 10 Leading Edges

The nose leading edge of the Hyper-X Mach 10 vehicle was orginally anticipated to reach temperatures near 4000 F at the leading-edge stagnation line. A SiC coated carbon/carbon (C/C) leading-edge material will not survive that extreme temperature for even a short duration single flight. To identify a suitable leading edge for the Mach 10 vehicle, arc-jet testing was performed on thirteen leading-edge segments fabricated from different material systems to evaluate their performance in a simulated flight environment. Hf, Zr, Si, and Ir based materials, in most cases as a coating on C/C, were included in the evaluation. Afterwards, MER, Tucson, AZ was selected as the supplier of the flight vehicle leading edges. The nose and the vertical and horizontal tail leading edges were fabricated out of a 3:1 biased high thermal conductivity C/C. The leading edges were coated with a three layer coating comprised of a SiC conversion of the top surface of the C/C, followed by a chemical vapor deposited layer of SiC, followed by a thin chemical vapor deposited layer of HfC. This paper will describe the fabrication of the Mach 10 C/C leading edges and the testing performed to validate performance

Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate

Role of Oxygen in Laser Induced Contamination at Diamond-Vacuum Interfaces

Many modern-day quantum science experiments rely on high-fidelity measurement of fluorescent signals emitted by the quantum system under study. A pernicious issue encountered when such experiments are conducted near a material interface in vacuum is "laser-induced contamination" (LIC): the gradual accretion of fluorescent contaminants on the surface where a laser is focused. Fluorescence from these contaminants can entirely drown out any signal from e.g. optically-probed color centers in the solid-state. Crucially, while LIC appears often in this context, it has not been systematically studied. In this work, we probe the onset and growth rate of LIC for a diamond nitrogen-vacancy center experiment in vacuum, and we correlate the contamination-induced fluorescence intensities to micron-scale physical build-up of contaminant on the diamond surface. Drawing upon similar phenomena previously studied in the space optics community, we use photo-catalyzed oxidation of contaminants as a mitigation strategy. We vary the residual oxygen pressure over 9 orders of magnitude and find that LIC growth is inhibited at near-atmospheric oxygen partial pressures, but the growth rate at lower oxygen pressure is non-monotonic. Finally, we discuss a model for the observed dependence of LIC growth rate on oxygen content and propose methods to extend in situ mitigation of LIC to a wider range of operating pressures.Comment: 22 pages, 10 figure

Tunnel vision, false memories, and intrusive memories following exposure to the Trier Social Stress Test

Most research examining the impact of stress on learning and memory has exposed participants to a stressor and measured how it affects learning and memory for unrelated material (e.g., list of words). Such work has been helpful, but it has not been the most translational to the human condition. When considering phenomena such as intrusive memories in post-traumatic stress disorder (PTSD) or an eyewitness\u27s memory for a crime, it is most useful to know what an individual remembers about the stress experience itself, not unrelated information. In prior work, investigators used a modified version of the Trier Social Stress Test (TSST) to quantify participant memory for the stressor. We aimed to replicate this work by examining participant memory for the TSST and extend on it by quantifying false and intrusive memories that result from TSST exposure. Forty-six undergraduate students from Ohio Northern University were exposed to the TSST or the friendly-TSST (f-TSST). The TSST required participants to deliver a ten-minute speech in front of two lab panel members as part of a mock job interview; the f-TSST required participants to casually converse with the panel members about their interests and hobbies. In both conditions, the panel members interacted with (central) or did not interact with (peripheral) several objects sitting on a desk in front of them. Participants’ anxiety levels were assessed before and after the TSST or f-TSST, and saliva samples were collected to assay for cortisol. The next day, participants’ memory for the objects that were present on Day 1 was assessed with recall and recognition tests. We also quantified participants’ intrusive memories for each task by having them complete an intrusive memory questionnaire on Days 2, 4, 6, and 8. Participants exposed to the TSST exhibited greater recall of central objects than participants exposed to the f-TSST. There were no differences observed for the recall of peripheral objects or for recognition memory. Interestingly, TSST exposure increased false recall in males, but reduced it in females. Females exposed to the TSST also showed greater evidence of intrusive memories than males exposed to the TSST. Consistent with prior work, these findings show that stress enhances memory for the central details of a stressful experience. They also extend on prior work by showing that stressful experiences sex-dependently impact the manifestation of false and intrusive memories. This is the first study of which we are aware to quantify intrusive memory formation with the TSST; the modified TSST paradigm may be useful in understanding differential susceptibility to intrusive memory formation and the development of PTSD

Young people doing dance doing gender: relational analysis and thinking intersectionally

Scraton (1992) asserts in her conclusion to ‘Shaping up to Womanhood’ that feminist analysis of PE (and sport and leisure more broadly) needs to engage more directly with masculinity as a means to understanding the ‘dynamics of gender’. Focusing on young people’s involvement in recreational dance, this paper demonstrates how some of those dynamics of gender are played out, reproduced and resisted by both boys and girls who participate at community based dance organisations. Selective data in the form of research frames are incorporated to illustrate how gender is constructed, enacted and embodied by young people engaged in recreational dance. Masculine and feminine hegemonies are highlighted and demonstrate that gender is both relational and intersectional. This contributes to ongoing analysis of masculinities and femininities as practices and processes imbued with complex power relations for young people

Divergent Roles of Clock Genes in Retinal and Suprachiasmatic Nucleus Circadian Oscillators

The retina is both a sensory organ and a self-sustained circadian clock. Gene targeting studies have revealed that mammalian circadian clocks generate molecular circadian rhythms through coupled transcription/translation feedback loops which involve 6 core clock genes, namely Period (Per) 1 and 2, Cryptochrome (Cry) 1 and 2, Clock, and Bmal1 and that the roles of individual clock genes in rhythms generation are tissue-specific. However, the mechanisms of molecular circadian rhythms in the mammalian retina are incompletely understood and the extent to which retinal neural clocks share mechanisms with the suprachiasmatic nucleus (SCN), the central neural clock, is unclear. In the present study, we examined the rhythmic amplitude and period of real-time bioluminescence rhythms in explants of retina from Per1-, Per2-, Per3-, Cry1-, Cry2-, and Clock-deficient mice that carried transgenic PERIOD2::LUCIFERASE (PER2::LUC) or Period1::luciferase (Per1::luc) circadian reporters. Per1-, Cry1- and Clock-deficient retinal and SCN explants showed weakened or disrupted rhythms, with stronger effects in retina compared to SCN. Per2, Per3, and Cry2 were individually dispensable for sustained rhythms in both tissues. Retinal and SCN explants from double knockouts of Cry1 and Cry2 were arrhythmic. Gene effects on period were divergent with reduction in the number of Per1 alleles shortening circadian period in retina, but lengthening it in SCN, and knockout of Per3 substantially shortening retinal clock period, but leaving SCN unaffected. Thus, the retinal neural clock has a unique pattern of clock gene dependence at the tissue level that it is similar in pattern, but more severe in degree, than the SCN neural clock, with divergent clock gene regulation of rhythmic period

Endocannabinoid Regulation of Acute and Protracted Nicotine Withdrawal: Effect of FAAH Inhibition

Evidence shows that the endocannabinoid system modulates the addictive properties of nicotine. In the present study, we hypothesized that spontaneous withdrawal resulting from removal of chronically implanted transdermal nicotine patches is regulated by the endocannabinoid system. A 7-day nicotine dependence procedure (5.2 mg/rat/day) elicited occurrence of reliable nicotine abstinence symptoms in Wistar rats. Somatic and affective withdrawal signs were observed at 16 and 34 hours following removal of nicotine patches, respectively. Further behavioral manifestations including decrease in locomotor activity and increased weight gain also occurred during withdrawal. Expression of spontaneous nicotine withdrawal was accompanied by fluctuation in levels of the endocannabinoid anandamide (AEA) in several brain structures including the amygdala, the hippocampus, the hypothalamus and the prefrontal cortex. Conversely, levels of 2-arachidonoyl-sn-glycerol were not significantly altered. Pharmacological inhibition of fatty acid amide hydrolase (FAAH), the enzyme responsible for the intracellular degradation of AEA, by URB597 (0.1 and 0.3 mg/kg, i.p.), reduced withdrawal-induced anxiety as assessed by the elevated plus maze test and the shock-probe defensive burying paradigm, but did not prevent the occurrence of somatic signs. Together, the results indicate that pharmacological strategies aimed at enhancing endocannabinoid signaling may offer therapeutic advantages to treat the negative affective state produced by nicotine withdrawal, which is critical for the maintenance of tobacco use