236 research outputs found

    Integration of Autonomous UAVs into Multi-agent Simulation

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    In recent years, Unmanned Aerial Vehicles (UAVs) have attracted much attention both in the research field and in the field of commercial deployment. Researchers recently started to study problems and opportunities connected with the usage, deployment and operation of teams of multiple autonomous UAVs. These multi-UAV scenarios are by their nature well suited to be modelled and simulated as multi-agent systems. In this paper we present solutions to the problems that we had to deal with in the process of integrating two hardware UAVs into an existing multi-agent simulation system with additional virtual UAVs, resulting in a mixed reality system where hardware UAVs and virtual UAVs can co-exist, coordinate their flight and cooperate on common tasks. Hardware UAVs are capable of on-board planning and reasoning, and can cooperate and coordinate their movement with one another, and also with virtual UAVs

    Extreme non-linear response of ultra-narrow optical transitions in cavity QED for laser stabilization

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    We explore the potential of direct spectroscopy of ultra-narrow optical transitions of atoms localized in an optical cavity. In contrast to stabilization against a reference cavity, which is the approach currently used for the most highly stabilized lasers, stabilization against an atomic transition does not suffer from Brownian thermal noise. Spectroscopy of ultra-narrow optical transitions in a cavity operates in a very highly saturated regime in which non-linear effects such as bistability play an important role. From the universal behavior of the Jaynes-Cummings model with dissipation, we derive the fundamental limits for laser stabilization using direct spectroscopy of ultra-narrow atomic lines. We find that with current lattice clock experiments, laser linewidths of about 1 mHz can be achieved in principle, and the ultimate limitations of this technique are at the 1 μ\mu Hz level.Comment: 5 pages, 4 figure

    Increased Respiratory Drive after Prolonged Isoflurane Sedation : A Retrospective Cohort Study

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    Low-dose isoflurane stimulates spontaneous breathing. We, therefore, tested the hypothesis that isoflurane compared to propofol sedation for at least 48 h is associated with increased respiratory drive in intensive care patients after sedation stop. All patients in our intensive care unit receiving at least 48 h of isoflurane or propofol sedation in 2019 were included. The primary outcome was increased respiratory drive over 72 h after sedation stop, defined as an arterial carbon dioxide pressure below 35 mmHg and a base excess more than −2 mmol/L. Secondary outcomes were acid–base balance and ventilatory parameters. We analyzed 64 patients, 23 patients sedated with isoflurane and 41 patients sedated with propofol. Patients sedated with isoflurane were about three times as likely to show increased respiratory drive after sedation stop than those sedated with propofol: adjusted risk ratio [95% confidence interval]: 2.9 [1.3, 6.5], p = 0.010. After sedation stop, tidal volumes were significantly greater and arterial carbon dioxide partial pressures were significantly lower, while respiratory rates did not differ in isoflurane versus propofol-sedated patients. In conclusion, prolonged isoflurane use in intensive care patients is associated with increased respiratory drive after sedation stop. Beneficial effects of isoflurane sedation on respiratory drive may, thus, extend beyond the actual period of sedation

    Washout and Awakening Times after Inhaled Sedation of Critically Ill Patients: Desflurane Versus Isoflurane

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    In recent years, inhaled sedation has been increasingly used in the intensive care unit (ICU). The aim of this prospective, controlled trial was to compare washout and awakening times after long term sedation with desflurane and isoflurane both administered with the MIRUS™ system (TIM GmbH, Koblenz, Germany). Twenty-one consecutive critically ill patients were alternately allocated to the two study groups, obtaining inhaled sedation with either desflurane or isoflurane. After 24 h study sedation, anesthetic washout curves were recorded, and a standardized wake-up test was performed. The primary outcome measure was the time required to decrease the endtidal concentration to 50% (T50%). Secondary outcome measures were T80% and awakening times (all extremities moved, RASS −2). Decrement times (min) (desflurane versus isoflurane, median (1st quartile—3rd quartile)) (T50%: 0.3 (0.3–0.4) vs. 1.3 (0.4–2.3), log-rank test P = 0.002; P80%: 2.5 (2–5.9) vs. 12.1 (5.1–20.2), P = 0.022) and awakening times (to RASS −2: 7.5 (5.5–8.8) vs. 41.0 (24.5–43.0), P = 0.007; all extremities moved: 5.0 (4.0–8.5) vs. 13.0 (8.0–41.25), P = 0.037) were significantly shorter after desflurane compared to isoflurane. The use of desflurane with the MIRUS™ system significantly shortens the washout times and leads to faster awakening after sedation of critically ill patients

    Ventilatory Effects of Isoflurane Sedation via the Sedaconda ACD-S versus ACD-L : A Substudy of a Randomized Trial

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    Devices used to deliver inhaled sedation increase dead space ventilation. We therefore compared ventilatory effects among isoflurane sedation via the Sedaconda ACD-S (internal volume: 50 mL), isoflurane sedation via the Sedaconda ACD-L (100 mL), and propofol sedation with standard mechanical ventilation with heat and moisture exchangers (HME). This is a substudy of a randomized trial that compared inhaled isoflurane sedation via the ACD-S or ACD-L to intravenous propofol sedation in 301 intensive care patients. Data from the first 24 h after study inclusion were analyzed using linear mixed models. Primary outcome was minute ventilation. Secondary outcomes were tidal volume, respiratory rate, arterial carbon dioxide pressure, and isoflurane consumption. In total, 151 patients were randomized to propofol and 150 to isoflurane sedation; 64 patients received isoflurane via the ACD-S and 86 patients via the ACD-L. While use of the ACD-L was associated with higher minute ventilation (average difference (95% confidence interval): 1.3 (0.7, 1.8) L/min, p < 0.001), higher tidal volumes (44 (16, 72) mL, p = 0.002), higher respiratory rates (1.2 (0.1, 2.2) breaths/min, p = 0.025), and higher arterial carbon dioxide pressures (3.4 (1.2, 5.6) mmHg, p = 0.002), use of the ACD-S did not significantly affect ventilation compared to standard mechanical ventilation and sedation. Isoflurane consumption was slightly less with the ACD-L compared to the ACD-S (−0.7 (−1.3, 0.1) mL/h, p = 0.022). The Sedaconda ACD-S compared to the ACD-L is associated with reduced minute ventilation and does not significantly affect ventilation compared to a standard mechanical ventilation and sedation setting. The smaller ACD-S is therefore the device of choice to minimize impact on ventilation, especially in patients with a limited ability to compensate (e.g., COPD patients). Volatile anesthetic consumption is slightly higher with the ACD-S compared to the ACD-L

    Dynamin function is important for chemokine receptor-induced cell migration.

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    The HIV viral entry co-receptors CCR5 and CXCR4 function physiologically as typical chemokine receptors. Activation leads to cytosolic signal transduction that results in a variety of cellular responses such as cytoskeletal rearrangement and chemotaxis (CTX). Our aim was to investigate the signalling pathways involved in CC and CXC receptor-mediated cell migration. Inhibition of dynamin I and II GTPase with dynasore completely inhibited CCL3-stimulated CTX in THP-1 cells, whereas the dynasore analogue Dyngo-4a, which is a more potent inhibitor, showed reduced ability to inhibit CC chemokine-induced CTX. In contrast, dynasore was not able to block cell migration via CXCR4. The same activation/inhibition pattern was verified in activated T lymphocytes for different CC and CXC chemokines. Cell migration induced by CC and CXC receptors does not rely on active internalization processes driven by dynamin because the blockade of internalization does not affect migration, but it might rely on dynamin interaction with the cytoskeleton. We identify here a functional difference in how CC and CXC receptor migration is controlled, suggesting that specific signalling networks are being employed for different receptor classes and potentially specific therapeutic targets to prevent receptor migration can be identified. Copyright © 2015 John Wiley & Sons, Ltd

    Benefit in liver transplantation: a survey among medical staff, patients, medical students and non-medical university staff and students

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    Background: The allocation of any scarce health care resource, especially a lifesaving resource, can create profound ethical and legal challenges. Liver transplant allocation currently is based upon urgency, a sickest-first approach, and does not utilize capacity to benefit. While urgency can be described reasonably well with the MELD system, benefit encompasses multiple dimensions of patients' well-being. Currently, the balance between both principles is ill-defined. Methods: This survey with 502 participants examines how urgency and benefit are weighted by different stakeholders (medical staff, patients on the liver transplant list or already transplanted, medical students and non-medical university staff and students). Results: Liver transplant patients favored the sickest-first allocation, although all other groups tended to favor benefit. Criteria of a successful transplantation were a minimum survival of at least 1 year and recovery of functional status to being ambulatory and capable of all self-care (ECOG 2). An individual delisting decision was accepted when the 1-year survival probability would fall below 50%. Benefit was found to be a critical variable that may also trigger the willingness to donate organs. Conclusions: The strong interest of stakeholder for successful liver transplants is inadequately translated into current allocation rules

    Hybrid Mechanical Systems

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    We discuss hybrid systems in which a mechanical oscillator is coupled to another (microscopic) quantum system, such as trapped atoms or ions, solid-state spin qubits, or superconducting devices. We summarize and compare different coupling schemes and describe first experimental implementations. Hybrid mechanical systems enable new approaches to quantum control of mechanical objects, precision sensing, and quantum information processing.Comment: To cite this review, please refer to the published book chapter (see Journal-ref and DOI). This v2 corresponds to the published versio

    Clients’ psychosocial communication and midwives’ verbal and nonverbal communication during prenatal counseling for anomaly screening

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    Objectives: This study focuses on facilitation of clients’ psychosocial communication during prenatal counseling for fetal anomaly screening. We assessed how psychosocial communication by clients is related to midwives’ psychosocial and affective communication, client-directed gaze and counseling duration. Methods: During 184 videotaped prenatal counseling consultations with 20 Dutch midwives, verbal psychosocial and affective behavior was measured by the Roter Interaction Analysis System (RIAS). We rated the duration of client-directed gaze. We performed multilevel analyses to assess the relation between clients’ psychosocial communication and midwives’ psychosocial and affective communication, client-directed gaze and counseling duration. Results: Clients’ psychosocial communication was higher if midwives’ asked more psychosocial questions and showed more affective behavior (b = 0.90; CI: 0.45–1.35; p < 0.00 and b = 1.32; CI: 0.18–2.47; p = 0.025, respectively). Clients “psychosocial communication was not related to midwives” clientdirected gaze. Additionally, psychosocial communication by clients was directly, positively related to the counseling duration (b = 0.59; CI: 0.20–099; p = 0.004). Conclusions: In contrast with our expectations, midwives’ client-directed gaze was not related with psychosocial communication of clients. Practice implications: In addition to asking psychosocial questions, our study shows that midwives’ affective behavior and counseling duration is likely to encourage client’s psychosocial communication, known to be especially important for facilitating decision-making
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