DAISIM: A Computational Simulator for the MakerDAO Stablecoin

We present a computational simulation of the single-collateral DAI stablecoin launched by the MakerDAO project in 2017. At the core of the simulation is a model of cryptocurrency investors acting as rational Markowitz mean-variance portfolio optimizers, with heterogeneous risk tolerance. The simulator, called DAISIM, incorporates automated order matching and price update mechanisms to determine the DAI price. We use the simulator to evaluate how the single-collateral DAI price, as well as portfolio allocations, vary for a given population of investors as a function of exogenous parameters such as the price of ETH and various system parameters including stability rate and transaction fee. DAISIM is being made available as open-source and may be useful in evaluating other similar projects

Effect of Adapting to Human Preferences on Trust in Human-Robot Teaming

We present the effect of adapting to human preferences on trust in a human-robot teaming task. The team performs a task in which the robot acts as an action recommender to the human. It is assumed that the behavior of the human and the robot is based on some reward function they try to optimize. We use a new human trust-behavior model that enables the robot to learn and adapt to the human's preferences in real-time during their interaction using Bayesian Inverse Reinforcement Learning. We present three strategies for the robot to interact with a human: a non-learner strategy, in which the robot assumes that the human's reward function is the same as the robot's, a non-adaptive learner strategy that learns the human's reward function for performance estimation, but still optimizes its own reward function, and an adaptive-learner strategy that learns the human's reward function for performance estimation and also optimizes this learned reward function. Results show that adapting to the human's reward function results in the highest trust in the robot.Comment: 6 pages, 6 figures, AAAI Fall Symposium on Agent Teaming in Mixed-Motive Situation

Evaluating the Impact of Personalized Value Alignment in Human-Robot Interaction: Insights into Trust and Team Performance Outcomes

This paper examines the effect of real-time, personalized alignment of a robot's reward function to the human's values on trust and team performance. We present and compare three distinct robot interaction strategies: a non-learner strategy where the robot presumes the human's reward function mirrors its own, a non-adaptive-learner strategy in which the robot learns the human's reward function for trust estimation and human behavior modeling, but still optimizes its own reward function, and an adaptive-learner strategy in which the robot learns the human's reward function and adopts it as its own. Two human-subject experiments with a total number of 54 participants were conducted. In both experiments, the human-robot team searches for potential threats in a town. The team sequentially goes through search sites to look for threats. We model the interaction between the human and the robot as a trust-aware Markov Decision Process (trust-aware MDP) and use Bayesian Inverse Reinforcement Learning (IRL) to estimate the reward weights of the human as they interact with the robot. In Experiment 1, we start our learning algorithm with an informed prior of the human's values/goals. In Experiment 2, we start the learning algorithm with an uninformed prior. Results indicate that when starting with a good informed prior, personalized value alignment does not seem to benefit trust or team performance. On the other hand, when an informed prior is unavailable, alignment to the human's values leads to high trust and higher perceived performance while maintaining the same objective team performance.Comment: 10 pages, 9 figures, to be published in ACM/IEEE International Conference on Human Robot Interaction. arXiv admin note: text overlap with arXiv:2309.0517

Salinity (Conductivity) Sensor Based on Parallel Plate Capacitors

This work is aimed at developing a high sensitivity salinity (conductivity) sensor for marine applications. The principle of sensing involves the use of parallel plate capacitors, which minimizes the proximity effects associated with inductive measurement techniques. The barrier properties of two different materials, AZ5214 and Honeywell\u27s ACCUFLO T3027, were investigated for use as the insulation layer for the sensor. Impedance analysis performed on the two coatings using Agilent\u27s 4924A Precision Impedance Analyzer served to prove that ACCUFLO was a better dielectric material for this application when compared to AZ5214.Two separate detection circuits have been proposed for the salinity sensor. In the Twin-T filter method, a variation in capacitance tends to shift the resonant frequency of a Twin-T oscillator, comprising the sensor. Simulations of the oscillator circuit were performed using Pspice. Experiments were performed on calibrated ocean water samples of 34.996 psu and a shift of 410 Hz/psu was obtained. To avoid the problems associated with the frequency drift in the oscillator, an alternate detection scheme is proposed which employs frequency-to-voltage converters. The sensitivity of this detection scheme was observed to be 10 mV/psu

Salinity (Conductivity) Sensor Based on Parallel Plate Capacitors

This work is aimed at developing a high sensitivity salinity (conductivity) sensor for marine applications. The principle of sensing involves the use of parallel plate capacitors, which minimizes the proximity effects associated with inductive measurement techniques. The barrier properties of two different materials, AZ5214 and Honeywell\u27s ACCUFLO T3027, were investigated for use as the insulation layer for the sensor. Impedance analysis performed on the two coatings using Agilent\u27s 4924A Precision Impedance Analyzer served to prove that ACCUFLO was a better dielectric material for this application when compared to AZ5214.Two separate detection circuits have been proposed for the salinity sensor. In the Twin-T filter method, a variation in capacitance tends to shift the resonant frequency of a Twin-T oscillator, comprising the sensor. Simulations of the oscillator circuit were performed using Pspice. Experiments were performed on calibrated ocean water samples of 34.996 psu and a shift of 410 Hz/psu was obtained. To avoid the problems associated with the frequency drift in the oscillator, an alternate detection scheme is proposed which employs frequency-to-voltage converters. The sensitivity of this detection scheme was observed to be 10 mV/psu

An analysis of the action of partial releasers on the conformational cycle of the serotonin transporter

Die Wiederaufnahme der Neurotransmitter Serotonin, Dopamin and Norepinephrin wird durch die entsprechenden Transporter (SERT, DAT, NET) vermittelt. Daher beenden sie einerseits die neuronale Signalübertragung und ermöglichen andererseits die Befüllung der synaptischen Vesikel mit Neurotransmittern, die für nachfolgende Signalübertragung wieder zur Verfügung stehen. Punktmutationen von SERT und DAT können zur Fehlfaltung der Transporter führen. Diese faltungsdefizienten Transporter werden im endoplasmatischen Retikulum (ER) zurückgehalten, weil die Qualitätskontrolle durch zytosolische Proteine und durch Proteine im Lumen des ER die Transporter verhindert, dass die mutierten Proteine in den sekretorischen Weg eingeschleust werden. Daher erreichen sie nicht die Zelloberfläche und stehen auch nicht für ihre Funktion, den Transport von Neurotransmittern, zur Verfügung. Faltungsdefiziente Mutationen von DAT sind klinisch relevant, weil sie zu einem Syndrom von Dystonie and Parkinsonismus führen. Dieses Dopamintransporter-Defizienz-Syndrom (DTDS) kann sich je nach der Art der Mutation zu unterschiedlichen Zeitpunkten manifestieren: Wenn der Faltungsdefekt gravierend ist, treten Symptome bereits bei Säuglingen auf. Mutationen, die mit einer residualen Transporteraktivität verbunden sind, führen zu einer juvenilen Form der Erkrankung. Einige dieser klinisch relevanten DAT-Mutanten können durch derzeit verfügbare Pharmakochaperone wie Noribogain und Bupropion korrigiert werden. Diese kleinen Moleküle binden an Faltungsintermediate der Transporter und korrigieren den Faltungsdefekt, indem sie die Energiebarrieren herabsetzen, die durch die Mutation im Faltungstrajektorium erzeugt werden. Dieser Effekt führt zur Wiederherstellung der Expression von Transportern an der Zelloberfläche und damit der Wiederaufnahme von Dopamin. Allerdings kann die Funktion bei der überwiegenden Zahl der DTDS-assoziierten DAT-Mutanten durch Noribogain oder Bupropion nicht wieder hergestellt werden. Daher besteht ein Bedarf an weiteren Pharmakochaperonen. Die vorliegende Arbeit stellt einen rationalen Zugang vor, wie potentielle Pharmakochaperone identifiziert werden können. Die Arbeitshypothese postuliert, dass Liganden als Pharmakochaperone wirken, wenn sie atypisch an SERT (und DAT) binden, d.h. in Konformationen einfrieren, die sich von denjenigen unterscheiden, in denen die Transporter in Gegenwart von typischen Inhibitoren und Substrates akkumulieren. Diese Annahme wurde experimentell überprüft: 1) Zunächst wurde der Wirkungsmechanismus von drei Amphetamin-ähnlichen Naphthylpropanaminen geklärt; PAL-1045, eines dieser Analoga, wirkt als partieller Freisetzer, der im Vergleich zum vollen Freisetzer p-Chloroamphetamin nur eingeschränkt Serotonin durch Transportumkehr aus Zellen freisetzt. 2) Die partielle Freisetzung wurde darauf zurückgeführt, dass PAL-1045 SERT in konformationellen Intermediaten einfriert. Folgerichtig wirkte PAL-1045 auch als Pharmakochaperon: Die Faltung der Mutante SERT-601PG602-AA wurde durch PAL-1045 teilweise korrigiert. 3) Mit PAL-1045 konnte die Rolle der Binding von Na+ und K+ im Transportzyklus von SERT untersucht werden. Mit diesen Beobachtungen konnte ein kinetisches Modell formuliert werden, in der die Bindung von Substrat und Cosubstrat-Ionen (Na+ und Cl-) in zufälliger Reihenfolge aber kooperativ stattfindet. Dieses Modell liefert nicht nur eine korrekte mechanistische Beschreibung des physiologischen Transportzyklus von SERT sondern auch der Transmitterfreisetzung durch Amphetamine und seine Analoga.Transporters for the monoamines serotonin (SERT), dopamine (DAT) and norepinephrine (NET) are integral membrane proteins, which function in reuptake and homeostatic recycling of extra-neuronal monoamines into synaptic vesicles. Hence, their actions effectively terminate neuronal signalling and provide for retrieved neurotransmitters to be reused for subsequent rounds of neurotransmission. Point mutations in SERT and DAT can cause misfolding of the transporters. Misfolded transporters are retained within the endoplasmic reticulum (ER) by a rigorous quality control machinery that employs cytosolic and ER luminal proteins. As a consequence, protein trafficking to the plasma membrane is impaired leading to loss of transporter function. Such mutations in DAT have clinical implications, because they result in a syndrome of dystonia and Parkinsonism in the affected individuals. The age of onset of this dopamine transporter deficiency syndrome (DTDS) depends on the nature of the mutation(s): severe folding deficiency results in an infantile onset. Mutations, which allow for some residual transport activity, lead to the juvenile form. A limited number of clinically relevant DAT mutants can be rescued by currently available pharmacochaperones like noribogaine and bupropion. These small molecules bind to mutant transporters and assist in correcting folding deficits by lowering energy barriers imposed by mutations within the protein folding trajectory. This restores surface expression and transporter function. However, the majority of DTDS-associated DAT mutants cannot be rescued with noribogaine or bupropion. This unmet medical need justifies the search for additional pharmacochaperones. The current thesis proposes a rational approach to screen for new ligands as potential pharmacochaperones. The underlying hypothesis posits that ligands can act as pharmacochaperones, if they exhibit atypical binding profiles to SERT (and DAT) and trap transporters in unique conformational states. The present work provides a proof of concept supporting this hypothesis: 1) The investigations focused on exploring the mechanism of action of naphthyl-propan-amines; one of the analogues PAL-1045, acts as a partial releaser, when compared to the full releaser p-chloroamphetamine. 2) This was linked to the ability of PAL-1045 to trap SERT in conformational intermediates, a property, which also conferred a pharmacochaperoning action to PAL-1045: folding of the ER-retained SERT-601PG602-AA mutant was restored in part by PAL-1045. 3) PAL-1045 allowed for interrogating the role of Na+ and K+ binding in the transport cycle of SERT: a kinetic model was proposed based on random, but cooperative, binding of substrates and co-substrate ions. This model provides for a mechanistic framework that explains not only the physiological transport cycle of SERT but also the releasing action of amphetamines.Abweichender Titel laut Übersetzung der Verfasserin/des VerfassersArbeit an der Bibliothek noch nicht eingelangt - Daten nicht geprüftMedizinische Universität Wien, Diss., 2018(VLID)306412

Effect of bio-ethanol on the performance and emission of a biodiesel fueled compression ignition engine

In the present study investigates the effect of bio-ethanol on the performance and emissions of a biodiesel blend fueled compression ignition engine. The experiments are conducted using pongamia biodiesel blend B20 (20% pongamia biodiesel +80% diesel) with 5, 7.5 and 10% (v/v) of bio-ethanol on a four stroke single cylinder diesel engine. The tests are conducted at different load conditions. Performance and emissions characteristics are investigated for different bio-ethanol compositions. The results show that the brake thermal efficiency is maximum for B20E7.5 blend with a minimum brake specific fuel consumption. Carbon monoxide emission is minimum for B20E7.5 blend and NOx emission decreases as the bio-ethanol percentage is increased from 5 to 7.5%. The study reveals that 7.5% bio-ethanol with B20 pongamia biodiesel blend results better performance and emission characteristics

Reinforced piezoresistive pressure sensor

A MEMS-based silicon pressure sensor for the ocean environment is presented. The invention is a multiple diaphragm piezoresistive pressure sensor for measuring the pressure of a liquid, comprising an inner deformable diaphragm formed on a silicon substrate, the inner deformable diaphragm having a first thickness an outer deformable diaphragm formed on the silicon substrate, the outer deformable diaphragm having a second thickness which is greater than the first thickness, positioned below the inner deformable diaphragm to support the inner deformable diaphragm, a first piezoresistive bridge embedded in the inner deformable diaphragm, a second piezoresistive bridge embedded in the outer deformable diaphragm and possibly a third piezoresistive bridge embedded in the silicon substrate to compensate for temperature variations