49 research outputs found

    Effects of Spatial Food Distribution on Search Behavior in Rats (Rattus norvegicus)

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    To analyze how search strategies are adapted according to the geometric distribution of food sources, the authors submitted rats to a search task in which they had to explore 9 food trays in an open field and avoid visiting already-depleted trays. Trays were spatially arranged in 4 independent configurations: a cross, a 3 × 3 matrix, 3 clusters of 3 trays each, and a random configuration. Rats exhibited differential search efficiency as a specific effect of the susceptibility of the configurations to being explored in a principled way: Crosses were first, matrices or clusters were in the middle, and random configurations were last. Although no exhaustive searches or highly principled patterns were observed in any of the configurations, performances improved as the sessions went by. Thus, structural affordances of the environment influence the construction not only of search strategies but also of information linked to where the reward is. © 2007 American Psychological Association

    Postpartum hemorrhage management, the importance of timing.

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    Postpartum hemorrhage is defined as a blood loss equal to or greater than 500 ml, which can occur from 24 hours to six weeks after delivery. It is a critical event with a rapid and devastating evolution, which can quickly lead to maternal shock and death. Many efforts have been made to create international and multisectoral guidelines that allow to face an event that represents the cause of about one quarter of maternal deaths. It is crucial to create a team able to act promptly in accordance with shared protocols. The availability of shared guidelines and protocols and the organization of periodic simulations and teamwork training are part of the fundamental initiatives that can promote the safety of perinatal care. The purpose of this document is to give clinicians the tools to minimize the risks associated with inadequate management of hemorrhagic emergency, avoiding the risk of “too little or too late” and giving patients maximum safety

    Coronary microvascular resistance: methods for its quantification in humans

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    Coronary microvascular dysfunction is a topic that has recently gained considerable interest in the medical community owing to the growing awareness that microvascular dysfunction occurs in a number of myocardial disease states and has important prognostic implications. With this growing awareness, comes the desire to accurately assess the functional capacity of the coronary microcirculation for diagnostic purposes as well as to monitor the effects of therapeutic interventions that are targeted at reversing the extent of coronary microvascular dysfunction. Measurements of coronary microvascular resistance play a pivotal role in achieving that goal and several invasive and noninvasive methods have been developed for its quantification. This review is intended to provide an update pertaining to the methodology of these different imaging techniques, including the discussion of their strengths and weaknesses

    Intraperitoneal drain placement and outcomes after elective colorectal surgery: international matched, prospective, cohort study

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    Despite current guidelines, intraperitoneal drain placement after elective colorectal surgery remains widespread. Drains were not associated with earlier detection of intraperitoneal collections, but were associated with prolonged hospital stay and increased risk of surgical-site infections.Background Many surgeons routinely place intraperitoneal drains after elective colorectal surgery. However, enhanced recovery after surgery guidelines recommend against their routine use owing to a lack of clear clinical benefit. This study aimed to describe international variation in intraperitoneal drain placement and the safety of this practice. Methods COMPASS (COMPlicAted intra-abdominal collectionS after colorectal Surgery) was a prospective, international, cohort study which enrolled consecutive adults undergoing elective colorectal surgery (February to March 2020). The primary outcome was the rate of intraperitoneal drain placement. Secondary outcomes included: rate and time to diagnosis of postoperative intraperitoneal collections; rate of surgical site infections (SSIs); time to discharge; and 30-day major postoperative complications (Clavien-Dindo grade at least III). After propensity score matching, multivariable logistic regression and Cox proportional hazards regression were used to estimate the independent association of the secondary outcomes with drain placement. Results Overall, 1805 patients from 22 countries were included (798 women, 44.2 per cent; median age 67.0 years). The drain insertion rate was 51.9 per cent (937 patients). After matching, drains were not associated with reduced rates (odds ratio (OR) 1.33, 95 per cent c.i. 0.79 to 2.23; P = 0.287) or earlier detection (hazard ratio (HR) 0.87, 0.33 to 2.31; P = 0.780) of collections. Although not associated with worse major postoperative complications (OR 1.09, 0.68 to 1.75; P = 0.709), drains were associated with delayed hospital discharge (HR 0.58, 0.52 to 0.66; P < 0.001) and an increased risk of SSIs (OR 2.47, 1.50 to 4.05; P < 0.001). Conclusion Intraperitoneal drain placement after elective colorectal surgery is not associated with earlier detection of postoperative collections, but prolongs hospital stay and increases SSI risk

    Coupled uRANS and FW- H Analysis of Installed Pusher Propeller Aircraft Configurations

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    In this paper the aeroacoustic phenomena characteristic of a pusher-propeller cofiguration and their aerodynamic causes are discussed and analyzed. The work was done in the frame of the European-funded project CESAR (Cost Effective Small AiRcraft). The configuration under study is an industrially relevant design with a wing-mounted pusher propeller, which features a close coupling of the turboshaft engines exhaust nozzles and a five bladed propeller. An established numerical analysis approach is applied in this study, which couples a high-fidelity unsteady aerodynamic simulation using the DLR TAU-Code with the DLR APSIM Code for a subsequent aeroacoustic evaluation. APSIM computes the sound propagation into the fareld based on the Ffowcs-Williams/Hawkings (FW-H) equations. A detailed analysis of the contributions of various components of the installation as well as flight condition specific parameters toward the overall noise generation by the propeller is presented. Furthermore, the possible scattering effect of the wing and nacelle is discussed. A detailed analysis of specific aspects of the numerical approach for the aeroacoustic analysis is made through a comparison between the results achieved using both a FW-H impermeable and permeable formulation. The numerical error due to both jet exhaust and propeller wake impingement on the FW-H permeable surface as well as the impact of cutting a hole in this permeable surface to avoid possible issues of these effects are discussed

    Digital twin of a combustion furnace operating in flameless conditions: Reduced-order model development from CFD simulations

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    The present paper presents the first-of-its-kind digital twin for a furnace operating in flameless combustion conditions. A methodology combining data compression, by means of Proper Orthogonal Decomposition (POD), and interpolation, using Kriging, was developed to design physics-based, reduced-order models (ROMs) for the prediction of combustion data at unexplored operating conditions. Three-dimensional simulations with detailed chemistry were carried out, spanning a wide range of operating conditions in terms of fuel composition (methane-hydrogen mixtures from pure methane to pure hydrogen), equivalence ratio (from 0.7 to 1) and air injector diameter (to adjust the air jet entrainment). Based on the available simulations, a ROM was developed, to predict both spatial fields, local and integral values of thermochemical variables at working conditions not included in the ROM development. Results showed that the developed ROM could reliably predict the temperature and main chemical species distribution in the furnace with an overall error below 10%, proving the effectiveness of the approach for the development of digital twins of combustion systems. A remarkable accuracy was observed for the prediction of specific quantities, including wall temperatures, OH decay length, OH peak value and location and exhaust gas composition, including pollutants, with prediction errors always below 5%, showing the potential of the approach to develop soft sensors.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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