Concentration Inequalities in the Wild: Case Studies in Blockchain & Reinforcement Learning

Concentration inequalities (CIs) are a powerful tool that provide probability bounds on how a random variable deviates from its expectation. In this dissertation, first I describe a blockchain protocol that I have developed, called Graphene, which uses CIs to provide probabilistic guarantees on performance. Second, I analyze the extent to which CIs are robust when the assumptions they require are violated, using Reinforcement Learning (RL) as the domain. Graphene is a method for interactive set reconciliation among peers in blockchains and related distributed systems. Through the novel combination of a Bloom filter and an Invertible Bloom Lookup Table, Graphene uses a fraction of the network bandwidth used by deployed work for one- and two-way synchronization. It is a fast and implementation-independent algorithm that uses CIs for parameterizing an IBLT so that it is optimal in size for a given desired decode rate. I characterize performance improvements through analysis, detailed simulation, and deployment results for Bitcoin Cash, a prominent cryptocurrency. Implementations of Graphene, IBLTs, and the IBLT optimization algorithm are all open-source code. Second, I analyze the extent to which existing methods rely on accurate training data for a specific class of RL algorithms, known as Safe and Seldonian RL. Several Seldonian RL algorithms have a component called the safety test, which uses CIs to lower bound the performance of a new policy with training data collected from another policy. I introduce a new measure of security to quantify the susceptibility to corruptions in training data, and show that a couple of Seldonian RL methods are extremely sensitive to even a few data corruptions, completely breaking the probability bounds guaranteed by CIs. I then introduce a new algorithm, called Panacea, that is more robust against data corruptions, and demonstrate its usage in practice on some RL problems, including a grid-world and diabetes treatment simulation

Radial lip seals, thermal aspects

In this paper the influence of temperature on tne seal-snarc contact is studied, using coupled temperature-stress FEH analysis. A thermal network model is used to calculate the seal-shaft contact temperature for steady-state and transient conditions. Contact temperatures were measured under the seal lip, employing different measurement techniques. The experimental and numerical results show good correspondence. This study demonstrates that the thermal network theory provides a useful tool to predict the seal-shaft contact temperature

The effects of tags on the evolution of honest signaling

In the study described here we examine the importance of social tags in the emergence and maintenance of signaling, using the Sir Philip Sydney Game. We use tags in the calcu-lation of inclusive fitness for members in a finite population, and analyze their evolution under different population distri-butions. We support the claim that inclusive fitness theory may not be sufficient to explain the evolution of cooperation. While cooperativity through honest signaling is sometimes achieved with tag-based relatedness, we suggest that the im-portance of tag-based mechanisms may not simply be due to their role in kin selection

Clinical case seminar - Hypogonadotropic hypogonadism as a presenting feature of late-onset X-linked adrenal hypoplasia congenita

Mutations in the orphan nuclear receptor DAX-1 cause X-linked adrenal hypoplasia congenita. Affected boys usually present with primary adrenal failure in early infancy or childhood. Impaired sexual development because of hypogonadotropic hypogonadism becomes apparent at the time of puberty. We report adult-onset adrenal hypoplasia congenita in a patient who presented with hypogonadism at 28 yr of age. Although he had no clinical evidence of adrenal dysfunction, compensated primary adrenal failure was diagnosed by biochemical testing. Semen analysis showed azoospermia, and he did not achieve fertility after 8 months of treatment with gonadotropins. A novel Y380D DAX-1 missense mutation, which causes partial loss of function in transient gene expression assays, was found in this patient. This case demonstrates that partial loss-of-function mutations in DAX1 can present with hypogonadotropic hypogonadism and covert adrenal failure in adulthood. Further, an important role for DAX-1 in spermatogenesis in humans is confirmed, supporting findings in the Dax1 (Ahch) knockout mouse

Mechanical, electronic and optical properties of Bi2S3 and Bi2Se3 compounds: first principle investigations

Cataloged from PDF version of article.The structural, mechanical, electronic, and optical properties of orthorhombic Bi2S3 and Bi2Se3 compounds have been investigated by means of first principles calculations. The calculated lattice parameters and internal coordinates are in very good agreement with the experimental findings. The elastic constants are obtained, then the secondary results such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, anisotropy factor, and Debye temperature of polycrystalline aggregates are derived, and the relevant mechanical properties are also discussed. Furthermore, the band structures and optical properties such as real and imaginary parts of dielectric functions, energy-loss function, the effective number of valance electrons, and the effective optical dielectric constant have been computed. We also calculated some non-linearities for Bi2S3 and Bi2Se3 (tensors of elasto-optical coefficients) under pressur

Design of a New Telescope Control System for Use in Astronomical Transient Events

Robotic autonomous telescopes provide highlevel control by selecting astronomical targets for observation, and they usually run under the control of a scheduler. TalonVIEW is a newly designed robotic autonomous telescope control system (TCS) for 16 inches telescope mount for use in astronomical transient events. The telescope control algorithm was implemented in PXI chassis written in GProgramming (LabVIEW) on realtime operating system(PharLab) from scratch. A new TCP/IP library was also implemented in Talon software to communicate with Pharlab in PXI chassis. Initial setup without any permanent pier and polar alignment showed that the pointing error of the telescope has been obtained as 2.22 arcminutes (132 arcseconds) in RA axis (horizontal axis of the image) and 25 arcseconds in Dec axis (vertical axis of the image), and tracking error has been observed as 4.8 arcseconds per second

Simultaneous localization and mapping with limited sensing using Extended Kalman Filter and Hough transform

Problem robota da izradi kartu nepoznatog okruženja uz ispravljanje vlastitog položaja na temelju iste karte i podataka senzora naziva se problem simultanog lokaliziranja i kartiranja (mapiranja). Budući da je točnost i preciznost senzora od velike važnosti u rješavanju tog problema, većina predloženih sustava uključuje primjenu skupih laserskih senzora daljine te relativno novije i jeftinije RGB-D kamere. Laserski senzori daljine su preskupi za neke primjene, a RGB-D kamere imaju veliku snagu, CPU ili sve što je potrebno za obradu podataka direktno ili na PC-u. Za izradu jeftinog robota bolje je primijeniti senzore niske cijene (poput infracrvenih ili sonarnih). Cilj je ovoga rada izraditi kartu nepoznatog okruženja uz primjenu jeftinog robota, produljenog Kalman filtra i linearnih obilježja, kao što su zidovi i namještaj. Ovdje se također predlaže pristup zatvaranja petlje. Eksperimenti su provedeni u okruženju Webots simulacije.The problem of a robot to create a map of an unknown environment while correcting its own position based on the same map and sensor data is called Simultaneous Localization and Mapping problem. As the accuracy and precision of the sensors have an important role in this problem, most of the proposed systems include the usage of high cost laser range sensors, and relatively newer and cheaper RGB-D cameras. Laser range sensors are too expensive for some implementations, and RGB-D cameras bring high power, CPU or communication requirements to process data on-board or on a PC. In order to build a low-cost robot it is more appropriate to use low-cost sensors (like infrared and sonar). In this study it is aimed to create a map of an unknown environment using a low cost robot, Extended Kalman Filter and linear features like walls and furniture. A loop closing approach is also proposed here. Experiments are performed in Webots simulation environment