An accurate and flexible analog emulation of AdEx neuron dynamics in silicon

Analog neuromorphic hardware promises fast brain emulation on the one hand and an efficient implementation of novel, brain-inspired computing paradigms on the other. Bridging this spectrum requires flexibly configurable circuits with reliable and reproducible dynamics fostered by an accurate implementation of the targeted neuron and synapse models. This manuscript presents the analog neuron circuits of the mixed-signal accelerated neuromorphic system BrainScaleS-2. They are capable of flexibly and accurately emulating the adaptive exponential leaky integrate-and-fire model equations in combination with both current- and conductance-based synapses, as demonstrated by precisely replicating a wide range of complex neuronal dynamics and firing patterns.Comment: Accepted for ICECS 202

Aufwachzeiten und Pharmakoelimination im Sedierungsfenster im Rahmen der Studie : Desfluran versus Isofluran zur inhalativen Sedierung kritisch kranker Patienten

1.1 Deutsche Zusammenfassung Einleitung: Kritisch kranke Patienten auf Intensivstation können intravenös oder inhalativ mittels volatiler Anästhetika sediert werden. Das Mirus™-System (TIM GmbH, Andernach, Deutschland) kann neben Isofluran und Sevofluran auch Desfluran applizieren. Die Fragestellung war, ob Desfluran gegenüber Isofluran nach etwa vierundzwanzigstündiger Sedierung im Konzentrationsbereich um 0,2-0,6 MAC (Minimale Alveoläre Konzentration, altersadjustiert) kürzere Auswasch- (Dekrement-) und Aufwachzeiten zeigt. Zusätzlich wurde der Anästhetikaverbrauch evaluiert. Registriert wurde die Studie im Deutschen Register Klinischer Studien (DRKS00011403). Methode: Zwanzig kritisch kranke Patienten wurden nach positivem Ethikvotum und Einwilligung der bevollmächtigten Betreuer in einer prospektiven, kontrollierten Studie alternierend mit Desfluran oder Isofluran sediert. In einem Sedierungsfenster wurden die Aufwachzeiten sowie die endtidalen Konzentrationen mittels Vamos-Gasmonitor (Drägerwerk AG & Co. KGaA, Lübeck, Deutschland) gemessen. Der Verbrauch wurde anhand der Mirus™-Log-Dateien berechnet. Ergebnisse: Nach (Mittelwert±Standardabweichung) 19,6±1,4 Sedierungs–stunden bei 0,45±0,14 MAC fiel die Desflurankonzentration nach 4:05 Min. auf 20%±6% der Ausgangskonzentration und erreichte nach 22:25 Min. 10%±4%. Die Isoflurankonzentration fiel nach 20,6±2,5 Sedierungsstunden bei 0,37±0,17 MAC nach 5:05 Min. auf 40%±19% der Ausgangskonzentration, verharrte dann aber für eine etwa eine Stunde zwischen 40% und 30%. Bereits die 50%-Dekrementzeit war signifikant kürzer nach Desfluran als nach Isofluran (0,3±0,1 Min. vs. 10,2±19,8 Min, p=0,002 Log-Rang-Test). Die Zeit bis Richmond Agitation-Sedation Scale -2 betrug 5,9±3,4 Min vs. 31,3±20,3 Min (p=0,004), bis Augenöffnen 3,3±3,1 Min. vs. 10,0±8,1 Min. (p=0,072), bis zum Befolgen von Aufforderungen (Bewegen aller Extremitäten) 6,4±4,4 Min. vs. 22,7±21,5 Min. (p=0,037). Der Anästhetikaverbrauch pro Stunde betrug 28,6±11,9 ml Desfluran und 4,3±2,6 ml Isofluran und korrelierte mit der Konzentration und dem Atemminutenvolumen (p<0,001). Handhabungs- oder andere Probleme während der Sedierungsphase traten nicht auf. Schlussfolgerung: Es konnte gezeigt werden, dass die etwa 20-stündige inhalative Sedierung kritisch kranker Patienten mit Desfluran mit kürzeren Dekrement- und Aufwachzeiten gegenüber der inhalativen Sedierung mit Isofluran einhergeht. Die Verbrauchswerte sind abhängig von Konzentration und Atemminutenvolumen. Zudem konnte sowohl Isofluran als auch Desfluran sicher angewendet werden.1.2 Abstract Awakening times and pharmacoelimination in line with the study: desflurane versus isoflurane for inhalation sedation of critically ill patients Objectives: Critically ill patients in intensive care unit can be sedated with either intravenous sedatives or by inhalation of volatile anaesthetics. Besides isoflurane and sevoflurane, the Mirus™ system (TIM GmbH, Andernach, Germany) can also administer desflurane. The issue was whether desflurane would show faster wash-out (decrement) times and shorter awakening times compared to isoflurane when used at sedative concentrations (0.2 to 0.6 of MAC = minimal alveolar concentration, age adjusted) over 24 hours. Additionally, the consumption of anaesthetics was evaluated. The study was registered in the German Registry of Clinical Studies (DRKS00011403). Methods: After ethical approval and informed consent of the legal representative, twenty critically ill patients were sedated alternately with desflurane or isoflurane in a prospective, controlled study. In a sedation window awakening was monitored and end-tidal concentrations were measured by the Vamos gas monitor (Drägerwerk AG & Co. KGaA, Lübeck, Germany). Consumption was analyzed on the basis of the Mirus™ log files. Results: After (mean±SD) 19.6±1.4 hours of sedation at 0.45±0.14 MAC, desflurane concentrations decreased to 20%±6% of the initial concentration after 4:05 minutes and continued to decrease, falling to 10%±4% after 22:25 min. After 20.6±2.5 hours at 0.37±0.17 MAC, isoflurane concentrations decreased to 40%±19% of the initial concentration after 5:05 minutes, but remained between 40% and 30% during the following hour. Already the 50% decrement times were significantly shorter with desflurane than with isoflurane (0.3±0.1 min vs. 10.2±19.8 min, p=0.002 Log-Rank Test). Time to Richmond Agitation-Sedation Scale -2 was 5.9±3.4 min vs. 31.3±20.3 min (p=0.004), time to eye-opening 3.3±3.1 min vs. 10.0±8.1 min (p=0.072), time to obeying commands (all extremities moved) 6.4±4.4 min vs. 22.7±21.5 min (p=0.037). Anaesthetic consumption per hour was 28.6±11,9 ml desflurane and 4,3±2,6 ml isoflurane, correlating with anaesthetic concentration and respiratory minute volume (p<0.001). There were no issues in handling or other problems during inhalation sedation. Conclusions: It could be shown that inhalation sedation of critically ill patients over about twenty hours with desflurane stands out by shorter decrement times and faster awakening compared to inhalation sedation with isoflurane. Consumption depends on concentration and respiratory minute volume. Furthermore, it can be stated that sedation with isoflurane and desflurane could be performed safely

Carbon nanotube based bolometer

The contacts of single carbon nanotubes and bundles of carbon nanotubes with superconducting and metallic electrodes are investigated in order to create bolometers and electron coolers. Tunneling contacts of the carbon nanotubes with aluminum electrodes are obtained. The current-voltage characteristics of junctions are analyzed for temperatures from room temperature to 300 mK. The resistance of individual nanotubes is primarily determined by defects and is too large for applications. The use of the bundles of carbon nanotubes makes it possible to considerably reduce the resistance of the bolometer, which is determined by a small number of conducting tubes with good tunneling contacts with the electrodes. The energy gap is equal to hundreds and tens of millivolt in the former and latter cases, respectively. Structures containing bundles of carbon nanotubes can be described in a model with a Schottky barrier. The samples with bundles of carbon nanotubes exhibit the bolometric response to external high-frequency radiation at a frequency of 110 GHz with an amplitude up to 100 &#956;V and a temperature voltage response to 0.4 mV/K

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

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

Demonstrating Analog Inference on the BrainScaleS-2 Mobile System

We present the BrainScaleS-2 mobile system as a compact analog inference engine based on the BrainScaleS-2 ASIC and demonstrate its capabilities at classifying a medical electrocardiogram dataset. The analog network core of the ASIC is utilized to perform the multiply-accumulate operations of a convolutional deep neural network. At a system power consumption of 5.6W, we measure a total energy consumption of 192uJ for the ASIC and achieve a classification time of 276us per electrocardiographic patient sample. Patients with atrial fibrillation are correctly identified with a detection rate of (93.7${\pm}$0.7)% at (14.0${\pm}$1.0)% false positives. The system is directly applicable to edge inference applications due to its small size, power envelope, and flexible I/O capabilities. It has enabled the BrainScaleS-2 ASIC to be operated reliably outside a specialized lab setting. In future applications, the system allows for a combination of conventional machine learning layers with online learning in spiking neural networks on a single neuromorphic platform