4,947 research outputs found
The discovery of lymphatic system as a turning point in medical knowledge: Aselli, Pecquet and the end of hepatocentrism
In this paper, I would like to analyse the impact of the discovery of lymphatic system on the development of the modern conception of human body. The discovery of lymphatics, as that of blood circulation, has in fact questioned important tenets of Galen's anatomo-physiology. Galen defended a 'dualistic conception' of the blood: he distinguished two different systems, the hepatic-venous system and the cardio-arterial one. The liver played a pivotal role because it was believed to transform the chyle received by the portal vein into venous blood. The discovery of lymphatics challenged this view: 17th-century anatomical dissections and experiments, starting with the discovery of milky veins by Gaspare Aselli (1581-1625) and the studies on thoracic duct by Jean Pecquet (1622-1674), irrefutably showed that the chyle does not pour out in the liver and that, consequently, the liver does not produce blood
Skylab experimental performance evaluation manual. Appendix Q: Experiment T-013 crew/vehicle disturbances (MSFC/LaRC)
A series of analyses to be used for evaluating the performance of the Skylab corollary experiments under preflight, inflight, and postflight conditions is given. Experiment contingency plan workaround procedure and malfunction analyses are presented in order to assist in making the experiment operationally successful
Limits on the Network Sensitivity Function for Multi-Agent Systems on a Graph
This report explores the tradeoffs and limits of performance in feedback control of interconnected multi-agent systems, focused on the network sensitivity functions. We consider the interaction topology described by a directed graph and we prove that the sensitivity transfer functions between every pair of agents, arbitrarily connected, can be derived using a version of the Mason's Direct Rule. Explicit forms for special types of graphs are presented. An analysis of the role of cycles points out that these structures influence and limit considerably the performance of the system. The more the cycles are equally distributed among the formation, the better performance the system can achieve, but they are always worse than the single agent case. We also prove the networked version of Bode's integral formula, showing that it still holds for multi-agent systems
Santorini, Giovanni Domenico
Voce biografica sul medico e anatomista veneziano Giovanni Domenico Santorini (1681-1737)
Selection of the key earth observation sensors and platforms focusing on applications for Polar Regions in the scope of Copernicus system 2020-2030
An optimal payload selection conducted in the frame of the H2020 ONION project (id 687490) is presented based on the ability to cover the observation needs of the Copernicus system in the time period 2020–2030. Payload selection is constrained by the variables that can be measured, the power consumption, and weight of the instrument, and the required accuracy and spatial resolution (horizontal or vertical). It involved 20 measurements with observation gaps according to the user requirements that were detected in the top 10 use cases in the scope of Copernicus space infrastructure, 9 potential applied technologies, and 39 available commercial platforms. Additional Earth Observation (EO) infrastructures are proposed to reduce measurements gaps, based on a weighting system that assigned high relevance for measurements associated to Marine for Weather Forecast over Polar Regions. This study concludes with a rank and mapping of the potential technologies and the suitable commercial platforms to cover most of the requirements of the top ten use cases, analyzing the Marine for Weather Forecast, Sea Ice Monitoring, Fishing Pressure, and Agriculture and Forestry: Hydric stress as the priority use cases.Peer ReviewedPostprint (published version
Conception of a simulator for a TEL system in orthopaedic surgery.
Within a research project whose aim is to promote the learning of percutaneous operation in orthopedic surgery, we investigate some representation models of empirical, deductive, and perceptivo-gestural knowledge. From these models, we design an TEL system (Tecnological Enhaced Learning) This project belongs to a multidisciplinary field including computer, orthopedic surgery, medical imaging, didactic and cognitive sciences. The article presents the design principles of TEL with a particular interest in the development of a simulator. This simulator allows a virtual exercise interacting with the learner in visual, temporal and haptic dimension
Coconut shells as filling material for anaerobic filters
In rural areas of developing countries, there is a lack of sanitation services and the installation of such infrastructure is hampered by the high investment costs for initial implementation and by the limited availability of qualified personnel. An alternative to traditional sanitation services include an anaerobic filter, but the high cost of appropriate filling material can be an obstacle to its wide-spread implementation. To decrease this construction cost, the objective of this work was to study the use of coconut shells as filling material for anaerobic filters. Anaerobic filters were built and filled with the studied material and operated with up flow and hydraulic retention time of 9 hours. The reactors provided a removal of 79 ± 16% in BOD terms, indicating that the coconut shell filling had efficiency consistent with the literature data. In addition, the husks were found to retain their tensile strength following use in the reactors. Coconut husks have more empty bed volume than other low cost materials, such as crushed stone, nearing properties of traditional materials. The results of this study indicate that coconut husks may prove to be a low cost alternative to traditional fillers for anaerobic treatment in rural communities
Melanin fate in the human epidermis: a re-assessment of how best to detect and analyze histologically
YesMelanin is the predominant pigment responsible for skin colour, and is synthesized by the
melanocyte in the basal layer of the epidermis and then transferred to surrounding keratinocytes.
Despite its optical properties, melanin is barely detectable in unstained sections of human skin.
However, identification and localization of melanin is of importance for the study of skin
pigmentation in health and disease. Current methods for the histologic quantification of melanin are
suboptimal, and are associated with significant risk of misinterpretation. The aim of this study was
to re-assess the existing literature, and to develop a more effective histological method of melanin
quantification in human skin.
Moreover, we confirm that Warthin-Starry (WS) stain provides a much more sensitive and more
specific melanin detection method than the common-place Fontana-Masson (FM) stain. For
example, WS staining sensitivity allowed the visualization of melanin even in very pale Caucasian
skin that was missed by FM or Von Kossa (VK) stains. From our re-assessment of the histologyrelated
literature we conclude that so-called ‘melanin dust’ is most likely an artefact of discoloration
due to non-specific silver deposition in the stratum corneum. Unlike FM and VK, WS was not
associated with this non-specific stratum corneum darkening, misinterpreted previously as
‘degraded’ or so-called ‘dust’ melanin. Finally, WS melanin particle counts were largely similar to
manual counts by transmission electron microscopy, in contrast to both FM and VK. Together these
findings allow us to propose a new histology/Image J-informed method for the accurate and precise
quantification of epidermal melanin in skin
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