POGO Instabilities Suppression Evaluation

A dynamic (frequency response) analysis was made of a liquid oxygen feed system consisting of a low-speed inducer, a high-speed main pump and a positive displacement pulser utilized for simulating pogo induced pressure oscillations. Based on the results of the analysis, an active control system for suppression of pulser generated pressure oscillations was designed, fabricated and tested. The test results verified that the suppressor was effective in attenuating the generated pressure oscillations over the frequency range from 10 to 30 Hz

Linear force and moment equations for an annular smooth shaft seal perturbed both angularly and laterally

Coefficients are derived for equations expressing the lateral force and pitching moments associated with both planar translation and angular perturbations from a nominally centered rotating shaft with respect to a stationary seal. The coefficients for the lowest order and first derivative terms emerge as being significant and are of approximately the same order of magnitude as the fundamental coefficients derived by means of Black's equations. Second derivative, shear perturbation, and entrance coefficient variation effects are adjudged to be small

Globalising assessment: an ethnography of literacy assessment, camels and fast food in the Mongolian Gobi

What happens when standardised literacy assessments travel globally? The paper presents an ethnographic account of adult literacy assessment events in rural Mongolia. It examines the dynamics of literacy assessment in terms of the movement and re-contextualisation of test items as they travel globally and are received locally by Mongolian respondents. The analysis of literacy assessment events is informed by Goodwin’s ‘participation framework’ on language as embodied and situated interactive phenomena and by Actor Network Theory. Actor Network Theory (ANT) is applied to examine literacy assessment events as processes of translation shaped by an ‘assemblage’ of human and non-human actors (including the assessment texts)

Circle talks as situated experiential learning: Context, identity, and knowledgeability in \u27learning from reflection\u27

This article presents research that used ethnographic and sociolinguistic methods to study ways participants learn through reflection when carried out as a “circle talk.” The data indicate that participants in the event (a) invoked different contextual frames that (b) implicated them in various identity positions, which (c) affected how they could express their knowledge. These features worked together to generate socially shared meanings that enabled participants to jointly achieve conceptualization—the ideational role “reflection” is presumed to play in the experiential learning process. The analysis supports the claim that participants generate new knowledge in reflection, but challenges individualistic and cognitive assumptions regarding how this occurs. The article builds on situated views of experiential learning by showing how knowledge can be understood as socially shared and how learning and identity formation are mutually entailing processes

Catalysis by electrons and holes: formal potential scales and preparative organic electrochemistry

The present review surveys current chemical understanding of catalysis by addition and removal of an electron. As an overarching theme of this type of catalysis, we introduce the role of redox scales in oxidation and reduction reactions as a direct analogue of pK_a scales in acid/base catalysis. Each scale is helpful in determining the type of reactivity to be expected. In addition, we describe several means of generating electrons and holes via chemical reactions, plasmonic resonance, radiolytic, photochemical and electrochemical methods. We specifically draw parallels between the now well-established fields of photoredox catalysis and chemical opportunities made available by electrochemical methods. We highlight accessible potential ranges for a series of electrochemical solvents and provide a discussion on experimental design, pitfalls and some remaining challenges in preparative organic electrochemistry

Is the near-death experience only N-methyl-D-aspartate blocking?

ABSTRACT: Karl Jansen's interesting hypothesis that near-death experi ences (NDEs) result from blockade of the N-methyl-D-aspartate receptor has several weaknesses. Some NDEs occur to individuals who are neither near death nor experiencing any event likely to upset cerebral physiology as Jan sen proposed; thus his hypothesis applies only to a subset of NDEs that occur in catastrophic circumstances. For that subset, the clarity of NDEs and the clear memory for the experience afterward are inconsistent with compromised cerebral function. Jansen's analogy between NDEs and ketamine-induced hallucinations is weakened by the fact that most ketamine users do not believe the events they perceived really happened. 'Iemporal lobe seizures do not resemble NDEs as Jansen postulated; they are confu sional, rarely ecstatic, and never clear, as are NDEs, nor are they remem bered afterward. Jansen's hypothesis assumes the standard scientific view that brain processes are entirely responsible for subjective experience; how ever, NDEs suggest that that concept of the mind may be too limited, and that in fact personal experience may continue beyond death of the brain. Karl L. R. Jansen has proposed a hypothesis describing a mecha nism that makes a major contribution to the understanding of the near-death experience (NDE). He suggested that the NDE is the re sult of the blocking of the phencyclidine (PCP) site on the N-methyl D-aspartate (NMDA) receptor

Kirigami-Inspired Organic and Inorganic Film-Based Flexible Thermoelectric Devices with Built-In Heat Sink

Thermoelectric (TE) devices can convert heat to electricity directly, which offers a unique opportunity to realize waste heat recovery. However, conventional TE devices inevitably use heat sinks, which are bulky, rigid and heavy, limiting practical applications. Herein, we propose a fully integrated film-based TE device with intrinsically built-in fins as heat sink in a hexagonal honeycomb device structure, that simultaneously achieves high TE performance and conformability, as confirmed by experiments and modelling. A flexible Kapton substrate with copper electrodes, integrating either carbon nanotube (CNT) veils or bismuth telluride (Bi2Te3) TE ‘legs’, both of n- and p-type, achieved a remarkable specific power of 185.4 nW K−2 for a Bi2Te3-based device and 53.1 nW K−2 for a CNT-based device, thanks to the heat dissipation effect granted by the built-in fins. Besides, the addition of oriented polymer films interconnects, contracting when above their glass transition temperature, allowed a single substrate two-dimensional (2D) TE device to self-fold into a three-dimensional (3D) hexagonal honeycomb structure, with built-in fins, contactlessly and autonomously. The demonstrated shape-programmed kirigami-inspired scalable TE device paves the way for realising self-powered applications comprising hundreds of TE legs with both inorganic (e.g., Bi2Te3) and organic (e.g. CNT veils) TE materials and integrated heat sinks

Influence of energy balance on the somatotrophic axis and matrix metalloproteinase expression in the endometrium of the postpartum dairy cow

Postpartum dairy cows enter a period of negative energy balance (NEB) associated with low circulating IGF1, during which the uterus must undergo extensive repair following calving. This study investigated the effects of NEB on expression of IGF family members and related genes in the involuting uterus. Cows were allocated to two treatments using differential feeding and milking regimes to produce mild NEB or severe NEB (SNEB). Uterine endometrial samples collected 2 weeks post partum were analysed by quantitative PCR. The expression of IGF-binding protein 4 (IGFBP4) mRNA increased in the endometrium of SNEB cows, with trends towards increased IGFBP1 and reduced IGFBP6 expression. There were no significant differences between treatments in mRNA expression of IGF1, IGF2 or of any hormone receptor studied, but significant correlations across all cows in the expression levels of groups of receptors suggested common regulatory mechanisms: type 1 IGF receptor (IGF1R), IGF2R and insulin receptor (INSR); GHR with ESR1; and ESR2 with NR3C1. The expression of IGF1R and INSR also positively correlated with the circulating urea concentration. Matrix metalloproteinases (MMPs) are important in tissue remodelling and can affect IGF signalling via interaction with IGFBPs. The expression levels of MMP1, MMP3, MMP9 and MMP13 mRNAs all showed major upregulation in the endometrium of cows in SNEB and all except MMP9 were highly correlated with expression of IGFBP4. Alpha(2)-HS-glycoprotein (AHSG) and PDK4, two genes implicated in insulin resistance, were also highly expressed in SNEB. These results suggest that cows in SNEB experience alterations to the IGF and insulin signalling pathways in the postpartum endometrium. This may affect the rate of tissue repair with a possible negative impact on subsequent fertility

Survey of Canadian Animal-Based Researchers' Views on the Three Rs: Replacement, Reduction and Refinement

The ‘Three Rs’ tenet (replacement, reduction, refinement) is a widely accepted cornerstone of Canadian and international policies on animal-based science. The Canadian Council on Animal Care (CCAC) initiated this web-based survey to obtain greater understanding of ‘principal investigators’ and ‘other researchers’ (i.e. graduate students, post-doctoral researchers etc.) views on the Three Rs, and to identify obstacles and opportunities for continued implementation of the Three Rs in Canada. Responses from 414 participants indicate that researchers currently do not view the goal of replacement as achievable. Researchers prefer to use enough animals to ensure quality data is obtained rather than using the minimum and potentially waste those animals if a problem occurs during the study. Many feel that they already reduce animal numbers as much as possible and have concerns that further reduction may compromise research. Most participants were ambivalent about re-use, but expressed concern that the practice could compromise experimental outcomes. In considering refinement, many researchers feel there are situations where animals should not receive pain relieving drugs because it may compromise scientific outcomes, although there was strong support for the Three Rs strategy of conducting animal welfare-related pilot studies, which were viewed as useful for both animal welfare and experimental design. Participants were not opposed to being offered “assistance” to implement the Three Rs, so long as the input is provided in a collegial manner, and from individuals who are perceived as experts. It may be useful for animal use policymakers to consider what steps are needed to make replacement a more feasible goal. In addition, initiatives that offer researchers greater practical and logistical support with Three Rs implementation may be useful. Encouragement and financial support for Three Rs initiatives may result in valuable contributions to Three Rs knowledge and improve welfare for animals used in science

Four Butterflies: End of Life Stories of Transition and Transformation

In this article, the author discusses her experiences as an Artist In Residence in the Department of Palliative Care and Rehabilitation Medicine at the University of Texas M. D. Anderson Cancer Center. Emphasis is placed on the ways in which end of life images and narratives often unfold in the fragile yet powerful space where conceptions of aesthetics and spirituality intersect with critical issues in the medical humanities. Drawing on four vivid case studies, the author examines the ways in which end of life narratives shed valuable light on conceptions of the subtlety of human embodiment; issues of violation, sorrow, and forgiveness; the mystical dimensions of traditional cultural beliefs; and the capacity for perceiving the natural world as a living symbol of grace. In so doing, she explores how the themes of transition and transformation become invested with meaningful existential and symbolic dimensions in artworks that give voice and presence to some of the most vulnerable, and often invisible, members of our societyﾗpeople at the end of life