1,721,109 research outputs found
Gestation-specific reference intervals for right and left ventricular ejection force from 12 to 40 weeks of gestation
No full textAim:? Ejection force of the fetal cardiac ventricles has previously been described from 18 weeks of gestation. We aimed to establish gestation-specific reference intervals for ventricular ejection force (VEF) from 12 to 40 weeks of pregnancy.Material and Methods:? In a cross-sectional observational study of singleton pregnancies, examinations were performed in 236 women evenly distributed across each week of pregnancy from 12 to 40 weeks. Each mother was scanned once. For the aortic and pulmonary valves, the time to peak velocity (TPV) and the average (TAV) and peak flow velocity in systole (PSV) was measured. For each we averaged values from three consecutive complexes. The outlet valve diameters were measured and the VEF on both the right and left sides were calculated using the formula VEF = (1.055 × valve area × time to peak velocity × TAV) × (PSV/TPV) where 1.055 represents the density of blood. Measurements were repeated in 40 women to assess intraobserver reproducibility and in 19 women for interobserver variability.Results:? We present reference intervals for right and left VEF. We demonstrated that the ventricular force on both right and left sides increases with advancing gestational age.Conclusion:? Fetal cardiac physiology can be studied and Doppler indices reliably measured as early as the late first trimester of pregnancy. Ventricular ejection force and its relationship with fetal growth could be explored in future studies and this may eventually provide better understanding of changes which may predispose to adult cardiac disease.<br/
Human interaction with an autonomous fault management system during simulated space flight operations
No full textDisplay Integration Enhances Information Sampling and Decision Making in Automated Fault Management in a Simulated Spaceflight Micro-World
No full textCognitive performance assessment in a complex space-system microworld: on the use of generalizability theory
No full textAutomated fault-management in a simulated spaceflight micro-world
No full textBackground: As human spaceflight missions extend in duration and distance from Earth, a self-sufficient crew will bear far greater onboard responsibility and authority for mission success. This will increase the need for automated fault management (FM). Human factors issues in the use of such systems include maintenance of cognitive skill, situational awareness (SA), trust in automation, and workload. This study examined the human performance consequences of operator use of intelligent FM support in interaction with an autonomous, space-related, atmospheric control system. Methods: An expert system representing a model-based reasoning agent supported operators at a low level of automation (LOA) by a computerized fault finding guide, at a medium LOA by an automated diagnosis and recovery advisory, and at a high LOA by automated diagnosis and recovery implementation, subject to operator approval or veto. Ten percent of the experimental trials involved complete failure of FM support. Results: Benefits of automation were reflected in more accurate diagnoses, shorter fault identification time, and reduced subjective operator workload. Unexpectedly, fault identification times deteriorated more at the medium than at the high LOA during automation failure. Analyses of information sampling behavior showed that offloading operators from recovery implementation during reliable automation enabled operators at high LOA to engage in fault assessment activities. Conclusions: The potential threat to SA imposed by high-level automation, in which decision advisories are automatically generated, need not inevitably be counteracted by choosing a lower LOA. Instead, freeing operator cognitive resources by automatic implementation of recovery plans at a higher LOA can promote better fault comprehension, so long as the automation interface is designed to support efficient information sampling
Consequences of shifting from one level of automation to another: main effects and their stability
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Examination of the proximity-compatibility principle in the design of displays in support of fault management in automated systems
No full textThe proximity-compatibility principle (PCP) proposed by Wickens and Carswell (1995) is examined on the basis of experimental results obtained with the process-control micro-world AUTO-CAMS. The PCP postulates a performance trade-off in display design that implies that display features that support information integration may degrade focused attention. In AUTO-CAMS information integration is required when operators, in case of system failures, have to engage in fault identification by mapping multiple anomaly symptoms to single root causes. Focused attention is demanded by one of the secondary tasks that require the operators to selectively read out gauge values while simultaneously ignoring other display elements. The AUTO-CAMS display was supplemented with an integrated display to support information integration implying the cost of deteriorating the focused attention task. In addition, two levels of automation of a model-based fault management reasoning agent were examined. In 70% of the trials this support was reliable. In the remaining trials, difficult double-faults occurred where the agents support became brittle in terms of identifying only one fault correctly, missing fault identification at all because of symptom masking, or giving a false fault identification. Only during brittle trials both PCP predictions could be confirmed: (1) The information integration task of fault identification was improved with the integrated display while the secondary focused attention task performance was deteriorated compared to the support with the non-integrated display. Means to cope with this trade-off problem are discussed
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