767 research outputs found

    Magnetospheric multiprobes: Investigations and instrumentation

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    The multiprobe scientific objectives are to: (1) determine the spatial structure of plasma phenomena such as the aurora, convection reversals, and ion troughs; (2) separate spatial and temporal variations in these phenomena; (3) determine field aligned current densities; (4) perform multiple point analysis of particle beams, wave fields, and plasma clouds that are injected into the ionosphere and magnetosphere by Spacelab active experiment facilities. Trade studies described include: instrument accommodations, power, attitude determination, electric field antennas, storage and ejection, thermal control, tracking communications, command and data management, payload and mission specialist support, functional objectives, and orbital analysis

    Wavelets and graph C∗C^*-algebras

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    Here we give an overview on the connection between wavelet theory and representation theory for graph C∗C^{\ast}-algebras, including the higher-rank graph C∗C^*-algebras of A. Kumjian and D. Pask. Many authors have studied different aspects of this connection over the last 20 years, and we begin this paper with a survey of the known results. We then discuss several new ways to generalize these results and obtain wavelets associated to representations of higher-rank graphs. In \cite{FGKP}, we introduced the "cubical wavelets" associated to a higher-rank graph. Here, we generalize this construction to build wavelets of arbitrary shapes. We also present a different but related construction of wavelets associated to a higher-rank graph, which we anticipate will have applications to traffic analysis on networks. Finally, we generalize the spectral graph wavelets of \cite{hammond} to higher-rank graphs, giving a third family of wavelets associated to higher-rank graphs

    A quantitative polymerase chain reaction-enzyme immunoassay for accurate measurements of human papillomavirus type 16 DNA levels in cervical scrapings

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    A quantitative polymerase chain reaction-enzyme immunoassay (Q-PCR-EIA) was developed to measure the amount of human papillomavirus (HPV) 16 DNA per genome equivalent in cervical scrapings. The quantitative approach was based on a combined competitive PCR for both HPV 16, using the general primer GP5+/6+ PCR, and β-globin DNA. The two competitive PCRs involve co-amplification of target sequences and exogenously added DNA constructs carrying a rearranged 30 bp sequence in the probe-binding region. The accuracy of quantification by combining the two competitive PCR assays was validated on mixtures of HPV 16 containing cervical cancer cells of CaSki and SiHa cell lines. Comparison of this fully quantitative PCR assay with two semi-quantitative HPV PCR assays on a series of crude cell suspensions from HPV 16 containing cervical scrapings revealed remarkable differences in the calculated relative HPV load between samples. We found evidence that correction for both intertube variations in PCR efficiency and number of input cells/integrity of DNA significantly influence the outcome of studies on viral DNA load in crude cell suspensions of cervical scrapings. Therefore, accurate measurements on viral DNA load in cervical scrapings require corrections for these phenomena, which can be achieved by application of this fully quantitative approach. © 1999 Cancer Research Campaig

    A qualitative study on the effects of psychoactive substance use upon artistic creativity

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    Background: Psychoactive substance use has often been claimed to help generate and facilitate the artistic creative process. Aims: The present study explored the role of artists’ substance use in their creative processes and their efforts to balance between enhancement and relaxation. Methods: Semi-structured interviews concerning the artistic creative process and the role of psychoactive substance use were recorded with 72 artists and analyzed using content analysis. The participants were classified according to their substance use in three groups (Cannabis Group, Alcohol Group, and Control Group). Results: Results show that both alcohol and cannabis were used to facilitate creativity and the emotional states that are necessary for the artistic creative process. Participants in the Control group reported that listening to music might function as a mind-altering tool. It was also found that for some artists, substance use is not only characteristic to creation, but it is also part of their everyday lives. Conclusion: Artists are aware of the balancing phenomenon during the artistic creative process. Whether psychoactive substance(s) or other environmental stimuli (such as music) are used to reach the required effect appears to depend upon the individual

    Different expressions of the same mode: a recent dialogue between archaeological and contemporary drawing practices

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    In this article we explore what we perceive as pertinent features of shared experience at the excavations of an Iron Age Hillfort at Bodfari, North Wales, referencing artist, archaeologist and examples of seminal art works and archaeological records resulting through inter-disciplinary collaboration. We explore ways along which archaeological and artistic practices of improvisation become entangled and productive through their different modes of mark-making. We contend that marks and memories of artist and archaeologist alike emerge interactively, through the mutually constituting effects of the object of study, the tools of exploration, and the practitioners themselves, when they are enmeshed in the cross-modally bound activities. These include, but are not limited to, remote sensing, surveying, mattocking, trowelling, drawing, photographing, videoing and sound recording. These marks represent the co-signatories: the gesture of the often anonymous practitioners, the voice of the deposits, as well as the imprint of the tools, and their interplay creates a multi-threaded narrative documenting their modes of intra-action, in short our practices. They occupy the conceptual space of paradata, and in the process of saturating the interstices of digital cognitive prosthetics they lend probity to their translations in both art form and archive

    Maximal-effort cytoreductive surgery for ovarian cancer patients with a high tumor burden: variations in practice and impact on outcome

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    Background This study aimed to compare the outcomes of two distinct patient populations treated within two neighboring UK cancer centers (A and B) for advanced epithelial ovarian cancer (EOC). Methods A retrospective analysis of all new stages 3 and 4 EOC patients treated between January 2013 and December 2014 was performed. The Mayo Clinic surgical complexity score (SCS) was applied. Cox regression analysis identified the impact of treatment methods on survival. Results The study identified 249 patients (127 at center A and 122 in centre B) without significant differences in International Federation of Gynecology and Obstetrics (FIGO) stage (FIGO 4, 29.7% at centers A and B), Eastern Cooperative Oncology Group (ECOG) performance status (ECOG < 2, 89.9% at centers A and B), or histology (serous type in 84.1% at centers A and B). The patients at center A were more likely to undergo surgery (87% vs 59.8%; p < 0.001). The types of chemotherapy and the patients receiving palliative treatment alone were equivalent between the two centers (3.6%). The median SCS was significantly higher at center A (9 vs 2; p < 0.001) with greater tumor burden (9 vs 6 abdominal fields involved; p < 0.001), longer median operation times (285 vs 155 min; p < 0.001), and longer hospital stays (9 vs 6 days; p < 0.001), but surgical morbidity and mortality were equivalent. The independent predictors of reduced overall survival (OS) were non-serous histology (hazard ratio [HR], 1.6; 95% confidence interval [CI] 1.04–2.61), ECOG higher than 2 (HR, 1.9; 95% CI 1.15–3.13), and palliation alone (HR, 3.43; 95% CI 1.51–7.81). Cytoreduction, of any timing, had an independent protective impact on OS compared with chemotherapy alone (HR, 0.31 for interval surgery and 0.39 for primary surgery), even after adjustment for other prognostic factors. Conclusions Incorporating surgery into the initial EOC management, even for those patients with a greater tumor burden and more disseminated disease, may require more complex procedures and more resources in terms of theater time and hospital stay, but seems to be associated with a significant prolongation of the patients overall survival compared with chemotherapy alone. Maximal-effort cytoreductive surgery aimed at total macroscopic tumor clearance combined with platinum-based chemotherapy and targeted agents is the cornerstone of modern primary epithelial ovarian cancer (EOC) management.1 Although findings have shown high tumor burden to be associated with a less favorable overall outcome than more advantageous tumor dissemination patterns with less disease,2 multiple prospective and retrospective series have long demonstrated a strong positive association between total macroscopic tumor clearance rates and survival, not only on an individual basis but also at the level of large patient cohorts, in which individual tumor biology-related factors are less likely to skew collective survival data.1,3, 4, 5, 6, 7, 8 The team of Chi et al. recently presented the survival data for all advanced EOC patients treated at Memorial Sloan Kettering categorized by year of primary debulking surgery based on the implementation of surgical changes in their approach to ovarian cancer debulking. Their study demonstrated that complete gross resection rates, progression-free survival (PFS) and overall survival (OS) increased during the 13-year evaluation period despite operating on higher-stage disease and patients with a greater tumor burden. This was assumed to be largely attributable to the surgical paradigm shifts implemented specifically to achieve more complete surgical cytoreduction, even for patients with a less favorable disease profile.4 Nevertheless, as with all medical and surgical advances, their broader implementation varies greatly nationally and internationally, not just due to differences in the available resources, but also because of long-established local practice and broad disparities in overall philosophy as well as in individual and infrastructural expertise.3,6,8,9 Especially for patients with a high tumor burden, in which therapeutic effort often is challenged, not only by the disease itself but also by the impact that this advanced disease has on the actual patient, both personal and infrastructural resources and expertise often are stretched, and hence reasonable doubt arises about the limitations and limits of optimal treatment.2,3,6 The current analysis aimed to demonstrate how differences in local practice may influence the patient’s outcome by evaluating not only the surgical patients, but also the entire EOC cohort treated at one of two large UK cancer centers in an attempt to exclude a selection bias of seemingly more favorable and operable patients7,10,11 and have all ovarian cancer patients in the denominator, including those women with more adverse tumor profiles and higher tumor load

    Assessing young people's political engagement: a critical and systematic literature review of the instruments used to measure political engagement

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    Over the past few decades, there has been an increasing interest in understanding youth political engagement. However, it has been argued that the instruments used to assess the concept often lack adequate validation, and this is important as this practice may result in biased statistical conclusions. Consequently, the main aim of the present study was to systematically review, summarize, and critique the extant research evidence on the development of psychometric instruments that assess young people’s political engagement. Following a systematic review of the literature, seven instruments were identified that were both valid and reliable, but none explicitly assessed young people’s political engagement. Instead, they considered broad concepts and/or dimensions related to political engagement. Emphasising the lack of statistically robust standardised measurement tools that empirically assess young people’s political engagement, the available evidence confirms the pressing need to adopt a robust psychometric approach to assess political engagement in youth

    First Evaluation of [11C]R116301 as an In Vivo Tracer of NK1 Receptors in Man

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    PURPOSE: NK1 receptors have been implicated in various neuropsychiatric and other disorders. R116301 is a selective NK1 receptor antagonist. In this pilot study, [(11)C]R116301 was evaluated as a potential positron emission tomography (PET) ligand for the NK1 receptor. PROCEDURES: Two dynamic PET studies were performed in three normal volunteers before and after a blocking dose of aprepitant. Data were analyzed using striatum to cerebellum standardized uptake value (SUV) ratios. RESULTS: Baseline SUV ratios at 60-90 min after injection ranged from 1.22 to 1.70. Following aprepitant administration, this specific signal was completely blocked. Aprepitant administration did not significantly affect uptake in cerebellum, confirming the absence of NK1 receptors in cerebellum. CONCLUSION: These preliminary results indicate that [(11)C]R116301 has potential as a radioligand for in vivo assessment of NK1 receptors in the human brai

    Influence of Oscillating Flow on LDL Transport and Wall Shear Stress in the Normal Aortic Arch

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    Lipid accumulation in the aortic wall is an important factor in the development of atherosclerosis. The Low Density Lipoprotein (LDL) at the surface of the endothelium in relation to Wall Shear Stress (WSS) in the normal human aortic arch under unsteady, normal flow and mass conditions was computationally analysed. Concave sides of the aortic arch exhibit, relatively to the convex ones, elevated LDL levels at the surface of the endothelium for all time steps. At the peak systolic velocity, the LDL level reaches a value 23.0% higher than that at entrance in the ascending-descending aorta region. The corresponding LDL levels at the surface of the endothelium for the near minimum entrance velocity instant reaches 26.0%. During the cardiac cycle, the highest area averaged normalized LDL taken up as compared to the lowest one is 0.69%. WSS plays an important role in the lipid accumulation. Low WSS regions are exposed to high LDL levels at the surface of the endothelium. Regions of elevated LDL levels do not necessarily co-locate to the sites of lowest WSS. The near wall paths of the velocities might be the most important factor for the elevated LDL levels at the surface of the endothelium
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