Investigation of vacuum tubes as four terminal networks

This thesis was undertaken with the aim of consolidating the most important work that has been done in the field of equivalent vacuum tube circuits which has been found to be highly disassociated. The author of this thesis feels that this thesis is the most complete consolidation of information on equivalent vacuum tube circuits --Introduction, page 3

Nanoparticle-based electrochemical sensors for the detection of lactate and hydrogen peroxide

In the present study, electrochemical sensors for the detection of lactate and hydrogen peroxide were constructed by exploiting the physicochemical properties of metal ad metal oxide nanoparticles. This study can be divided into two main sections. While chapter 2, 3, and 4 report on the construction of electrochemical lactate biosensors using CeO2 and CeO2-based mixed metal oxide nanoparticles, chapter 5 and 6 show the development of electrochemical hydrogen peroxide sensors by the decoration of the electrode surface with palladium-based nanoparticles. First generation oxidase enzyme-based sensors suffer from oxygen dependency which results in errors in the response current of the sensors in O2-lean environments. To address this challenge, the surface of the sensors must be modified with oxygen rich materials. In this regard, we developed a novel electrochemical lactate biosensor design by exploiting the oxygen storage capacity of CeO2 and CeO 2-CuO nanoparticles. By the introduction of CeO2 nanoparticles into the enzyme layer of the sensors, negative interference effect of ascorbate which resulted from the formation of oxygen-lean regions was eliminated successfully. When CeO2-based design was exposed to higher degree of O2 -depleted environments, however, the response current of the biosensors experienced an almost 21 % decrease, showing that the OSC of CeO2 was not high enough to sustain the enzymatic reactions. When CeO2-CuO nanoparticles, which have 5 times higher OSC than pristine CeO2, were used as an oxygen supply in the enzyme layer, the biosensors did not show any drop in the performance when moving from oxygen-rich to oxygen-lean conditions. In the second part of the study, PdCu/SPCE and PdAg/rGO-based electrochemical H2O2 sensors were designed and their performances were evaluated to determine their sensitivity, linear range, detection limit, and storage stability. In addition, practical applicability of the sensors was studied in human serum. The chronoamperometry results showed that the PdCu/SPCE sensors yielded a high sensitivity (396.7 µA mM -1 cm-2), a wide linear range (0.5 -11 mM), and a low limit of detection (0.7 µM) at the applied potential of -0.3 V. For PdAg/rGO sensors, a high sensitivity of 247.6 ± 2.7 µA˙mM -1˙cm-2 was obtained towards H2O 2 in a linear range of 0.05 mM to 28 mM

Understanding Ad Blockers

This project aims to provide useful information for users and researchers who would like to learn more about ad blocking. Three main research areas are explored in this project. The first research area provides general information about ad blocking tools and aims to explore ad blockers from a user’s perspective. The second research area provides analyses regarding third-party sites that appear on popular first-party sites in order to explore the behavior of third-parties. Finally, the third research area provides analyses regarding filter lists, which are sets of ad filtering rules used by ad blocking tools. The third research area aims to convey the differences and similarities between individual filter lists as well as sets of filter lists that form the defaults of ad blocking tools

A comparison of different irrigation systems and gravitational effect on final extrusion of the irrigant

Background: The aim of this study was to compare manual needle irrigation (MNI), RinsEndo (RE), and passive ultrasonic irrigation (PUI), and assess the effect of gravity on extrusion from the apex in vitro. Material and Methods: The distobuccal roots of molars were used and the canals were instrumented up to F2. Teeth were mounted on models, which permitted visualization and manipulation of the apices for necessary procedures. The models were placed in articulator to simulate the jaw. Six groups (G) were formed as: G1, G2 and G3 represented mandibular positioning of teeth and were irrigated with MNI, RE, and PUI, respectively, while G4, G5, and G6 represented maxillary positioning of teeth and were also irrigated in same sequence. Prior to the final irrigation, 72 cube-shaped foam pieces covered with aluminum foil were weighed and the values were recorded as the initial weights. The cubes were then placed on the apical part of each sample. Final irrigation was performed with distilled water and the cubes were weighed again to determine their final weights. Data were analyzed using Kruskal-Wallis and Mann-Whitney U post-hoc test ( p <0.05). Results: Irrespective of the irrigation technique used, the amount of irrigant extruded from the apex showed a statistically significant difference related to the effect of gravity ( p <0.05). There was no statistically significant difference between irrigation methods ( p >0.05). When the irrigation systems were compared to examine the effect of gravity, the significant difference was found between G2 and G5 ( p <0.05). Conclusions: Within the limitations of this study, MNI and PUI were found to be reliable irrigation systems. Caution should be exercised when using RinsEndo

The Role of Metal Oxide Layers in the Sensitivity of Lactate Biosensors Subjected to Oxygen-Limited Conditions

Amperometric lactate biosensors are used to detect lactate concentration in blood and tissues, which is integral in identifying cyanide poisoning, septic shock, and athletic condition. The construction of lactate biosensors with high sensitivity, selectivity, and stability is imperative to diagnose and determine these medical conditions. Lactate detection is currently limited to oxygen-rich environments due to the fact that oxygen is a limiting factor in the lactate reaction. To circumvent this problem, researchers have developed mediators or alternate, oxygen-free enzymes to improve sensitivity. In our study, ceria (CeO2) with high oxygen storage capacity (OSC) was introduced to the enzyme layer to eliminate the effects of oxygen depletion. Fluctuation in oxygen concentration was combatted by use of ceria metal oxide nanopowders, which absorb and release oxygen under oxygen rich and lean conditions respectively. These nanopowders were deposited on the electrode surface in a polyelectrolyte solution. The lactate biosensors were then constructed using layer-by-layer assembly to take advantage of electrostatic interaction between the positively charged polyelectrolyte and negatively charged lactate oxidase (LOx). Polyethylenimine (PEI), a positively charged polymer, was used to immobilize the enzymes on the Pt surface via alternating electrostatic adsorption. It was observed that the introduction of ceria in the enzyme layer reduced oxygen dependency. The results showed that lactate biosensors with high selectivity, sensitivity, and wide detection limit were constructed

FPGA Implementation of a Frame Synchronization Algorithm for Powerline Communications

This paper presents an FPGA implementation of a pilot–based time synchronization scheme employing orthogonal frequency division multiplexing for powerline communication channels. The functionality of the algorithm is analyzed and tested over a real powerline residential network. For this purpose, an appropriate transmitter circuit, implemented by an FPGA, and suitable coupling circuits are constructed. The system has been developed using VHDL language on Nallatech XtremeDSP development kits. The communication system operates in the baseband up to 30 MHz. Measurements of the algorithm's good performance in terms of the number of detected frames and timing offset error are taken and compared to simulations of existing algorithms

Assigning Course Schedules: About Preference Elicitation, Fairness, and Truthfulness

Most organizations face distributed scheduling problems where private preferences of individuals mat­ter. Course assignment is a widespread example arising in educational institutions and beyond. Often students have preferences for course schedules over the week. First­Come­First­Served (FCFS) is the most widely used assignment rule in practice, but it is inefficient and unfair. Recent work on randomized match­ing suggests an alternative with attractive properties – Bundled Probabilistic Serial (BPS). A major chal­lenge in BPS is that the mechanism requires the participants’ preferences for exponentially many schedules. We describe a way to elicit preferences reducing the number of required parameters to a manageable set. We report results from field experiments, which allow us to analyze important empirical metrics of the as­ signments compared to FCFS. These metrics were central for the adoption of BPS at a major university. The overall system design yields an effective approach to solve daunting distributed scheduling tasks in organizations

Matching with Bundle Preferences: Tradeoff between Fairness and Truthfulness

Course assignment is a widespread problem in education. Often students have preferences for course schedules over the week. First-Come First-Served (FCFS) is the most widely used rule to assign students to courses in practice, but recent research led to alternatives with attractive properties. Bundled Probabilistic Serial (BPS) is a randomized mechanism satisfying ordinal efficiency, envy-freeness, weak strategy-proofness, and polynomial runtime. We report a first application of BPS in a large-scale course assignment application and discuss advantages over FCFS comparing a number of metrics such as the size, the average rank, the profile, and the popularity of the assignments. The exponential number of possible course schedules is a central problem in the implementation of combinatorial assignment mechanisms. We propose a new way to elicit preferences, which limits the number of parameters a student needs to provide. This yields a computationally very effective tool to solve course assignment problems with thousands of students in practice