Learned Legendre Predictive State Estimator for Control

This thesis introduces a novel method for system model identification, specifically for state estimation. The method uses a 2 or 3 layer neural network developed and trained with the methods of the Neural Engineering Framework (NEF). Using the NEF allows for direct control of what the different layers represent with white-box modelling of the layers. NEF networks also have the added benefit of being compilable onto neuromorphic hardware, which can run on an order of magnitude or more less power than conventional computing hardware. The first layer of the network is optional and uses a Legendre Delay Network (LDN). The LDN implements a linear operation that performs a mathematically optimal compression of a time series of data, which in this context is the input signal to the network. This allows for temporal information to be encoded and passed into the network. The LDN frames the problem of memory as delaying a signal by some length θ seconds. Using the linear transfer function for a continuous-time delay, F(s) = e−θs, the LDN compression is considered optimal as it uses Pad´e approximants to represent the delay, which has been proven optimal for this purpose. The LDN has been shown to outperform other memory cells, such as long short-term memory (LSTM) and gated recurrent units (GRU), by several orders of magnitude, and is capable of representing over 1,000,000 timesteps of data. The LDN forms a polynomial representation of a sliding window of length θ, allowing for a continuous representation of the time series. The second layer uses the Learned Legendre Predictor (LLP) to make predictions of how a subset of the input signal to this layer will evolve over a future window of time. In the case of model estimation, using the system states and control signal (at minimum), the LLP layer predicts how the system states will evolve over a continuous window into the future. The LLP uses a similar time series compression as the LDN, but of the representation of the layer prediction into the future. The weights for the LLP layer can be trained online or offline. The third layer of the network performs the transformation out of the Legendre domain into the units of the input signal to be predicted. Since the second layer outputs a polynomial representation of the state prediction, the state at any time in the prediction window can be extracted with a linear operation. Combined, the three layer network is referred to as the Learned Legendre Predictive State Estimator (LLPSE). The 2 layer version, without LDN context encoding, is tested online on a single link inverted pendulum and is able to predict the angle of the arm 30 timesteps into the future while learning the system dynamics online. The 3 layer LLPSE is trained offline to predict the future position of a simulated quadrotor over a continuous window of 1 second in length. The training, validation, and test data is generated in AirSim with Unreal Engine 4. The LLPSE is able to predict the future second of a simulated quadrotor’s position with an average RMSE of 0.0067 on the network’s normalized representation space of position (normalized from a 30x30x15 meter volume). Future work is discussed, with initial steps provided for using the LLPSE for model predictive control (MPC). A controller, the Learned Legendre Predictive Controller (LLPC), is designed and tested for state estimation across the control space. The design and future steps of the LLPC are discussed in the final chapter. A preliminary LLPC is designed and was integrated into the test suite, and is available along with all of the code for simulator interfacing, controllers, path planning, the LLP systems, and various utility functions at https://github.com/p3jawors/masters thesis

25(OH)D Concentration in Neonates, Infants, and Toddlers From Poland—Evaluation of Trends During Years 1981–2011

Introduction: The numerous evidence showing spectrum of vitamin D effects on human health resulted in both updates of vitamin D supplementation guidelines for general population and concerns on potential risk of hypercalcaemia. The aim of this study was to analyse trends in serum 25-hydroxyvitamin D concentration (25(OH)D) change over the 30 years of operation of a single pediatric diagnostic unit.Materials and methods: Calcium-phosphate metabolism markers and 25(OH)D concentrations were analyzed in a group that consisted of newborns and infants commissioned for diagnostics due to suspected calcium-phosphate metabolic disturbances (n = 3,163; mean age 8.0 ± 3.0 months).Results: 25(OH)D < 10 ng/ml was noted in 4.5% of patients (n = 163), 10–20 ng/ml in 14.7% (n = 465), 20–30 ng/ml in 23.9% (n = 756) and 30–50 ng/ml in 35.9% (n = 1,136). The mean 25(OH)D concentration in analyzed group was 37.5 ± 24.5 ng/ml. In patients with 25(OH)D concentration < 10 ng/ml a normal calcaemia (2.25–2.65 mmol/l) was noted in 83.4% cases (n = 136). Eighty one patients had 25(OH)D concentrations above 100 ng/ml with co-existing calcaemia in range of 2.6–4.38 mmol/l (mean Ca = 2.69 mmol/l). Hypocalcaemia (Ca < 2.25 mmol/l) was observed in 0.54%, (n = 17). 13.8% patients revealed calcium levels >2.65 mmol/l (n = 435). In general, the mean calcium-phosphate markers values were within the reference range for age. The highest mean 25(OH)D concentration of 51.8 ng/ml ± 38.8 was noted in years 1981–1999 (n = 305). The lowest mean 25(OH)D value was observed in years 2010–2011 (29.0 ng/ml ± 13.6; n = 412). The trend of decreasing 25(OH)D concentration during analyzed time period was significant (r = −0.29, p < 0.0001).Conclusions: Eighty percentage of children aged 0–36 months had 25(OH)D concentration >20 ng/ml, however, during 3 decades a mean 25(OH)D concentrations trended significantly to decrease. A direct relationship between low 25(OH)D concentration and hypocalcaemia was not observed nor between high 25(OH)D concentration and hypercalcemia

Structure and Function of the Campylobacter jejuni Chromosome Replication Origin

Campylobacter jejuni is the leading bacterial cause of foodborne infections worldwide. However, our understanding of its cell cycle is poor. We identified the probable C. jejuni origin of replication (oriC) – a key element for initiation of chromosome replication, which is also important for chromosome structure, maintenance and dynamics. The herein characterized C. jejuni oriC is monopartite and contains (i) the DnaA box cluster, (ii) the DnaA-dependent DNA unwinding element (DUE) and (iii) binding sites for regulatory proteins. The cluster of five DnaA boxes and the DUE were found in the dnaA-dnaN intergenic region. Binding of DnaA to this cluster of DnaA-boxes enabled unwinding of the DUE in vitro. However, it was not sufficient to sustain replication of minichromosomes, unless the cluster was extended by additional DnaA boxes located in the 3′ end of dnaA. This suggests, that C. jejuni oriC requires these boxes to initiate or to regulate replication of its chromosome. However, further detailed mutagenesis is required to confirm the role of these two boxes in initiation of C. jejuni chromosome replication and thus to confirm partial localization of C. jejuni oriC within a coding region, which has not been reported thus far for any bacterial oriC. In vitro DUE unwinding by DnaA was inhibited by Cj1509, an orphan response regulator and a homolog of HP1021, that has been previously shown to inhibit replication in Helicobacter pylori. Thus, Cj1509 might play a similar role as a regulator of C. jejuni chromosome replication. This is the first systematic analysis of chromosome replication initiation in C. jejuni, and we expect that these studies will provide a basis for future research examining the structure and dynamics of the C. jejuni chromosome, which will be crucial for understanding the pathogens’ life cycle and virulence

Genetic determinants of heel bone properties: genome-wide association meta-analysis and replication in the GEFOS/GENOMOS consortium

Quantitative ultrasound of the heel captures heel bone properties that independently predict fracture risk and, with bone mineral density (BMD) assessed by X-ray (DXA), may be convenient alternatives for evaluating osteoporosis and fracture risk. We performed a meta-analysis of genome-wide association (GWA) studies to assess the genetic determinants of heel broadband ultrasound attenuation (BUA; n = 14 260), velocity of sound (VOS; n = 15 514) and BMD (n = 4566) in 13 discovery cohorts. Independent replication involved seven cohorts with GWA data (in silico n = 11 452) and new genotyping in 15 cohorts (de novo n = 24 902). In combined random effects, meta-analysis of the discovery and replication cohorts, nine single nucleotide polymorphisms (SNPs) had genome-wide significant (P < 5 × 10(-8)) associations with heel bone properties. Alongside SNPs within or near previously identified osteoporosis susceptibility genes including ESR1 (6q25.1: rs4869739, rs3020331, rs2982552), SPTBN1 (2p16.2: rs11898505), RSPO3 (6q22.33: rs7741021), WNT16 (7q31.31: rs2908007), DKK1 (10q21.1: rs7902708) and GPATCH1 (19q13.11: rs10416265), we identified a new locus on chromosome 11q14.2 (rs597319 close to TMEM135, a gene recently linked to osteoblastogenesis and longevity) significantly associated with both BUA and VOS (P < 8.23 × 10(-14)). In meta-analyses involving 25 cohorts with up to 14 985 fracture cases, six of 10 SNPs associated with heel bone properties at P < 5 × 10(-6) also had the expected direction of association with any fracture (P < 0.05), including three SNPs with P < 0.005: 6q22.33 (rs7741021), 7q31.31 (rs2908007) and 10q21.1 (rs7902708). In conclusion, this GWA study reveals the effect of several genes common to central DXA-derived BMD and heel ultrasound/DXA measures and points to a new genetic locus with potential implications for better understanding of osteoporosis pathophysiology

Solidaritet och diplomati : Svenskt fackligt och diplomatiskt stöd till Polens demokratisering under 1980-talet

Polens förvandling från kommunistisk enpartistat till liberalt folkstyre var först och främst ett verk av landets demokratiska opposition och i synnerhet av den oberoende fackliga rörelsen Solidaritet. Men länderna i väst spelade också en roll genom sitt stöd till oppositionen. I det stödet tog Sverige en aktiv del. Den svenska fackföreningsrörelsen var tidigt närvarande i det polska dramat och lämnade under 1980-talet materiellt och moraliskt stöd, ofta i samarbete med polska aktivister i Sverige. Svensk diplomati odlade samtidigt livliga kontakter med den polska oppositionen och arbetade för att regimen skulle välja samförståndets och dialogens väg. Den ”svenska modellen” uppmärksammades både inom regimen och oppositionen och bidrog till att göra svenskarna till intressanta samtalspartners. Den svenska fackföreningsrörelsens och diplomatins insatser under 1980-talet har föga uppmärksammats i den historiska forskningen. Mycket skedde i det fördolda.Paweł Jaworskis forskning finansierades av Svenska Institutet och polska Narodowe Centrum Nauki (UMO-2011/2011/01/B/HS3/00714).</p

Comparison of the Effectiveness of Selected Vibration Signal Analysis Methods in the Rotor Unbalance Detection of PMSM Drive System

Mechanical unbalance is a phenomenon that concerns rotating elements, including rotors in electrical machines. An unbalanced rotor generates vibration, which is transferred to the machine body. The vibration contributes to reducing drive system reliability and, as a consequence, leads to frequent downtime. Therefore, from an economic point of view, monitoring the unbalance of rotating elements is justified. In this paper, the rotor unbalance of a drive system with a permanent magnet synchronous motor (PMSM) was physically modelled using a specially developed shield, with five test masses fixed at the motor shaft. The analysed diagnostic signal was mechanical vibration. Unbalance was detected using selected signal analysis methods, such as frequency-domain methods (classical spectrum analysis FFT and a higher-order bispectrum method) and two methods applied in technical diagnostics (order analysis and orbit method). The efficiency of unbalance symptom detection using these four methods was compared for the frequency controlled PMSM. The properties of the analysed diagnostic methods were assessed and compared in terms of their usefulness in rotor unbalance diagnosis, and the basic features characterizing the usefulness of these methods were determined depending on the operating conditions of the drive. This work could have a significant impact on the process of designing diagnostic systems for PMSM drives