329 research outputs found

    Centrifugal acceleration in the magnetotail lobes

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    Combined Cluster EFW and EDI measurements have shown that cold ion outflow in the magnetospheric lobes dominates the hydrogen ion outflow from the Earth's atmosphere. The ions have too low kinetic energy to be measurable with particle instruments, at least for the typical spacecraft potential of a sunlit spacecraft in the tenuous lobe plasmas outside a few <I>R</I><sub>E</sub>. The measurement technique yields both density and bulk velocity, which can be combined with magnetic field measurements to estimate the centrifugal acceleration experienced by these particles. We present a quantitative estimate of the centrifugal acceleration, and the velocity change with distance which we would expect due to centrifugal acceleration. It is found that the centrifugal acceleration is on average outward with an average value of about of 5 m s<sup>−2</sup>. This is small, but acting during long transport times and over long distances the cumulative effect is significant, while still consistent with the relatively low velocities estimated using the combination of EFW and EDI data. The centrifugal acceleration should accelerate any oxygen ions in the lobes to energies observable by particle spectrometers. The data set also put constraints on the effectiveness of any other acceleration mechanisms acting in the lobes, where the total velocity increase between 5 and 19 <I>R</I><sub>E</sub> geocentric distance is less than 5 km s<sup>−1</sup>

    Longitudinal phase space manipulation in energy recovering linac-driven free-electron lasers

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    Energy recovering an electron beam after it has participated in a free-electron laser (FEL) interaction can be quite challenging because of the substantial FEL-induced energy spread and the energy anti-damping that occurs during deceleration. In the Jefferson Lab infrared FEL driver-accelerator, such an energy recovery scheme was implemented by properly matching the longitudinal phase space throughout the recirculation transport by employing the so-called energy compression scheme. In the present paper,after presenting a single-particle dynamics approach of the method used to energy-recover the electron beam, we report on experimental validation of the method obtained by measurements of the so-called "compression efficiency" and "momentum compaction" lattice transfer maps at different locations in the recirculation transport line. We also compare these measurements with numerical tracking simulations.Comment: 31 pages, 13 figures, submitted to Phys. Rev. Special Topics A&

    Design Thinking: Project Portfolio Management and Simulation – A Creative Mix for Research

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    This paper takes de Bono’s explanation of ‘design thinking’ as the starting point for a report on a doctoral research project that began with a conventional ‘why?’ question, and then, instead of looking for an ‘explanation’, chose to look forward in time to establish an understanding of ‘how to’ think differently about a recurring problem. The catalyst for this work was observation of otherwise competent managers making desperately wrong decisions when good decision making was crucial to their company’s future. The initial choice to ‘look forward’ when designing the research strategy was made well before there was a clear understanding of what was being observed. Given that trajectory, this paper explores the process by which a simulation was created and then used in conjunction with a comparatively new approach to data collection (Explanation looks backwards and design looks forward [1].)

    Prenatal Metal Exposure Alters the Placental Proteome in a Sex-Dependent Manner in Extremely Low Gestational Age Newborns: Links to Gestational Age

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    Prenatal exposure to toxic metals is associated with altered placental function and adverse infant and child health outcomes. Adverse outcomes include those that are observed at the time of birth, such as low birthweight, as well as those that arise later in life, such as neurological impairment. It is often the case that these adverse outcomes show sex-specific responses in relation to toxicant exposures. While the precise molecular mechanisms linking in utero toxic metal exposures with later-in-life health are unknown, placental inflammation is posited to play a critical role. Here, we sought to understand whether in utero metal exposure is associated with alterations in the expression of the placental proteome by identifying metal associated proteins (MAPs). Within the Extremely Low Gestational Age Newborns (ELGAN) cohort (n = 230), placental and umbilical cord tissue samples were collected at birth. Arsenic (As), cadmium (Cd), lead (Pb), selenium (Se), and manganese (Mn) concentrations were measured in umbilical cord tissue samples via ICP-MS/MS. Protein expression was examined in placental samples using an LC-MS/MS-based, global, untargeted proteomics analysis measuring more than 3400 proteins. MAPs were then evaluated for associations with pregnancy and neonatal outcomes, including placental weight and gestational age. We hypothesized that metal levels would be positively associated with the altered expression of inflammation/immune-associated pathways and that sex-specific patterns of metal-associated placental protein expression would be observed. Sex-specific analyses identified 89 unique MAPs expressed in female placentas and 41 unique MAPs expressed in male placentas. Notably, many of the female-associated MAPs are known to be involved in immune-related processes, while the male-associated MAPs are associated with intracellular transport and cell localization. Further, several MAPs were significantly associated with gestational age in males and females and placental weight in males. These data highlight the linkage between prenatal metal exposure and an altered placental proteome, with implications for altering the trajectory of fetal development

    Feasibility study of the National Autistic Society EarlyBird parent support programme

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    The EarlyBird programme is a group-based psychoeducation intervention for parents of young children with autism. Although it is widely used in the United Kingdom, the evidence base for the programme is very limited. Using a mixed method, non-randomised research design, we aimed to test (1) the acceptability of the research procedures (recruitment, retention, suitability of measures), (2) the parental acceptability of EarlyBird (attendance, views of the programme, perceived changes) and (3) the facilitator acceptability of EarlyBird (fidelity, views of the programme, perceived changes). Seventeen families with a 2- to 5-year-old autistic child and 10 EarlyBird facilitators took part. Pre- and post-intervention assessment included measures of the child’s autism characteristics, cognitive ability, adaptive behaviour, emotional and behavioural problems and parent-reported autism knowledge, parenting competence, stress and wellbeing. Semi-structured interviews were completed at post-intervention with parents and facilitators. For those involved in the study, the research procedures were generally acceptable, retention rates were high and the research protocol was administered as planned. Generally, positive views of the intervention were expressed by parents and facilitators. Although the uncontrolled, within-participant design does not allow us to test for efficacy, change in several outcome measures from pre- to post-intervention was in the expected direction. Difficulties were encountered with recruitment (opt-in to the groups was ~56% and opt-in to the research was 63%), and strategies to enhance recruitment need to be built into any future trial. These findings should be used to inform protocols for pragmatic, controlled trials of EarlyBird and other group-based interventions for parents with young autistic children

    Inactivation of promoter 1B of APC causes partial gene silencing: evidence for a significant role of the promoter in regulation and causative of familial adenomatous polyposis

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    Familial adenomatous polyposis (FAP) is caused by germline mutations in the adenomatous polyposis coli (APC) gene. Two promoters, 1A and 1B, have been recognized in APC, and 1B is thought to have a minor role in the regulation of the gene. We have identified a novel deletion encompassing half of this promoter in the largest family (Family 1) of the Swedish Polyposis Registry. The mutation leads to an imbalance in allele-specific expression of APC, and transcription from promoter 1B was highly impaired in both normal colorectal mucosa and blood from mutation carriers. To establish the significance of promoter 1B in normal colorectal mucosa (from controls), expression levels of specific transcripts from each of the promoters, 1A and 1B, were examined, and the expression from 1B was significantly higher compared with 1A. Significant amounts of transcripts generated from promoter 1B were also determined in a panel of 20 various normal tissues examined. In FAP-related tumors, the APC germline mutation is proposed to dictate the second hit. Mutations leaving two or three out of seven 20-amino-acid repeats in the central domain of APC intact seem to be required for tumorigenesis. We examined adenomas from mutation carriers in Family 1 for second hits in the entire gene without any findings, however, loss of the residual expression of the deleterious allele was observed. Three major conclusions of significant importance in relation to the function of APC can be drawn from this study; (i) germline inactivation of promoter 1B is disease causing in FAP; (ii) expression of transcripts from promoter 1B is generated at considerable higher levels compared with 1A, demonstrating a hitherto unknown importance of 1B; (iii) adenoma formation in FAP, caused by impaired function of promoter 1B, does not require homozygous inactivation of APC allowing for alternative genetic models as basis for adenoma formation

    Understanding the rift, the (still) uneasy bedfellows of History and Organization Studies

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    Although the use of History has become increasingly discussed and more widely applied within Organization Studies (OS), its relevance for OS still remains far from centrally accepted. This article historicizes the relationship between Sociology and History as a means of better understanding the tensions, perceived and real, that exist between History and Organization Studies. In particular we analyse three differences of epistemological standpoint (method, objectivity and usefulness) that are commonly seen as the foundation stones to incompatibility. Perhaps surprisingly for an analysis of apparent disciplinary differences, we find that these distinctions in terms of approach, once closely examined, are rarely clear-cut and historians and OS scholars are frequently closer in intention and method than they are distant. However, despite their large intersection of interests, we argue that important distinctions between the two fields should be acknowledged. Our contribution to the debates over the need for more historical approaches within OS therefore centrally rests on abandoning aspirations for fully integrative models of working together, in favour of cooperative modes that concede the fields’ differences. This subtle shift of emphasis will, we believe, greatly benefit OS scholars who hope to include historical perspectives in their work
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