A hybrid quantum-classical approach for inference on restricted Boltzmann machines

Boltzmann machine is a powerful machine learning model with many real-world applications, for example by constructing deep belief networks. Statistical inference on a Boltzmann machine can be carried out by sampling from its posterior distribution. However, uniform sampling from such a model is not trivial due to an extremely multi-modal distribution. Quantum computers have the promise of solving some non-trivial problems in an efficient manner. We explored the application of a D-Wave quantum annealer to generate samples from a restricted Boltzmann machine. The samples are further improved by Markov chains in a hybrid quantum-classical setup. We demonstrated that quantum annealer samples can improve the performance of Gibbs sampling compared to random initialization. The hybrid setup is considerably more efficient than a pure classical sampling. We also investigated the impact of annealing parameters (temperature) to improve the quality of samples. By increasing the amount of classical processing (Gibbs updates) the benefit of quantum annealing vanishes, which may be justified by the limited performance of today's quantum computers compared to classical.Comment: 23 pages, 12 figure

Presence of Human Bocavirus 1 in Hospitalised Children with Acute Respiratory Tract Infections in Latvia and Lithuania

Funding Information: This study was supported by Republic of China (Taiwan)-Republic of Latvia-Republic of Lithuania scientific collaboration project, "Establishing of the framework to track molecular epidemiology of Parvoviruses and to correlate sequence variability with different clinical manifestations" (Research Council of Latvia Nr. gr. 6-25/2012/0026, Research Council of Lithuania TAPLLT02/201) and by project Nr. RSU ZP 17/2013 "Epidemiology, pathogenicity of human Bocavirus (HBoV) species and possible association with lower respiratory tract illnesses and acute gastroenteritis in children". We are grateful to Rita Nikitenkiene and Irina Maksimova for technical help. Publisher Copyright: © 2016 by Zaiga Nora-Krūkle. Copyright: Copyright 2016 Elsevier B.V., All rights reserved.Human bocavirus 1 (HBoV1) is a parvovirus recently found to be a possible aetiologic agent of acute respiratory disease in children. We conducted the first clinical and molecular study on this virus in Latvia (LV) and Lithuania (LT). The aim of the study was to determine the occurrence of HBoV1 in respiratory tract samples taken from hospitalised children with acute respiratory tract infections in LV and LT. In total 186 children with age one to 50 months, and who fulfilled criteria of acute respiratory tract infection, including lower respiratory tract infections, with or without fever, were included in this study. A nasopharyngeal aspirate was obtained from each patient on admission. DNA was isolated and polimerase chain reaction (PCR) performed targeting the HBoV1 NS1sequence. HBoV1 positive samples were sequenced and phylogenetic analysis was performed. HBoV1 sequence was detected in 42 (32%) of 130 LV and in 8 (14%) of 56 LT samples. In LV the majority of patients with HBoV1 infection were observed in February while in LT in October. The phylogenetic tree for HBoV1 indicated that isolates of HBoV1 cluster closely and include almost all of the isolates in this study. HBoV1 is common in Latvia and Lithuania and might be a significant pathogen that contributes to acute respiratory tract infections in children.Peer reviewe

The Use of Video Tutorials in Promoting Pupils’ Understanding of Mathematics

Šajā darbā ir izpētīta teorija par video kā mācību materiāla formātu, apzināta Latvijas un pasau- les pieredze, izmantojot mācību video, un apkopota un analizēta informācija par macibuvideo.lv pieejamo mācību video lietojumu un tā atbilstību labai praksei. Praktiskās daļas būtiskākais pie- nesums ir iepriekš nekur nepublicētu datu analīze par macibuvideo.lv apmeklējumu un detalizē- tāk – par šajā vietnē pieejamo mācību video – lietojumu. Galvenais secinājums – veids, kā tiek skatīti mācību video ir ļoti dažāds, tāpēc, veidojot mācību materiālus, mēs nevaram pieņemt, ka skolēni tos redzēs no sākuma līdz beigām. Apmeklējuma dati apstiprina, ka skola ir galvenais motivators skatīties mācību video.This thesis analyses the available theoretical basis for video as an instructional media, gathers information about the use of video tutorials in Latvia and internationally, as well as offers and analyses information on the use of video tutorials on macibuvideo.lv and its consistency with good practices. The main contribution of this thesis to the knowledge base is the analysis of previously unpublished data on macibuvideo.lv and the use of the videos available on this site. The main conclusion is that the ways the videos are viewed vary. Authors of learning resources cannot assume that the resources will be used from the beginning to the end. Data on macibu- video.lv visits supports the conclusion that the main motivator to view the videos on the site is schoolwork

Quantum algorithm implementation on a physical quantum computer

Darbā aprakstītas kvantu programmēšanas vides IBM Quantum Experience un Rigetti fiziskajiem kvantu datoriem — to iespējas un ierobežojumi, salīdzinājumā ar teorētisko kvantu algoritmu izstrādi. Apskatīti vairāki kvantu galīgā automāta realizācijas risinājumi, to efektivitāte un ierobežojumi darbībā fiziskā kvantu ierīcē un simulatorā. Lai gan pilnībā kvantu galīgo automātu publiski pieejamajos kvantu datoros šobrīd nevar realizēt, atsevišķus tā aspektus var. Realizācijas kvalitāti būtiski ietekmē divu kubitu loģisko elementu skaits un darbībai izvēlēto fizisko kubitu kvalitāte — dekoherences laiks un loģisko elementu izpildes kļūdas.This thesis reviews programming environments for IBM Quantum Experience and Rigetti physical quantum computers. Functionality and limitations compared to theoretical quantum algorithm development are described. Several implementations of a quantum finite automaton are presented, and their efficiency and effectiveness on the physical devices and a simulator for a physical device are analysed. Although it is not possible to fully implement a quantum finite automaton on a physical device, some of its aspects can be implemented. The efficiency depends substantially on the number of two-qubit gates and the quality of the physical qubits used

Optimisation of Widefield Fluorescence Fret System for Studying Separate Molecule Interactions

The Förster Resonance Energy Transfer (FRET) method has wide application in modern science for studying protein–protein interactions and conformational changes. FRET allows to assess molecular interactions by measuring energy transfer between acceptor and donor fluorophores coupled to the molecule(s) of interest. The method demands high precision in experimental design, experimental settings and correct data interpretation. Therefore, we tested several parameters to estimate FRET measurement accuracy in our Nikon wide-field fluorescence FRET system. The experiments were performed in a HEK-293 cell line transfected with DNA constructs expressing Calcium Release-Activated Channel (CRAC) subunits STIM1 and ORAI1 coupled to donor fluorophore Cyan Fluorescent Protein (CFP) and acceptor fluorophore Yellow Fluorescent Protein (YFP), respectively. Exposure time and approach of data analysis varied throughout experiments in order to optimise FRET data quality. Dependence of FRETeff values on measurement quality and donor/acceptor fluorophore ratio in the cells was estimated. We demonstrated that, using the wide-field fluorescence FRET system, minimising the exposure of fluorophores before measurement using neutral density (ND) filters considerably minimises undesirable photo-bleaching of the fluorophores. There was a strong correlation between the CFP/YFP ratio in the cells and the observed FRET level, suggesting that only cells with certain donor/acceptor ratio might be comparable. We also showed impact of FRET measurement quality, defined as accordance of FRET pixels to Gaussian distribution, on FRET artefacts. Knowledge obtained during our experiments may be important for approbating similar wide-field fluorescence FRET systems to study two separate molecule interactions and for understanding the correct setup of the experiments and data interpretation

Characterisation and In Vivo Safety of Canine Adipose-Derived Stem Cells

The study characterises canine adipose-derived stem cells (cASCs) in comparison to human ASCs (hASCs) and tests their safety in a canine model after intravenous administration. cASCs from two dogs were cultured under hypoxic conditions in a medium supplemented with autologous serum. They were plastic adherent, spindle-shaped cells that expressed CD73, CD90, and CD44 but lacked CD45, CD14, HLA-DR, and CD34. cASCs differentiated toward adipogenic, osteogenic, and chondrogenic lineages, although adipogenic differentiation capacity was low. Blast transformation reaction demonstrated that these cells significantly suppress T-cell proliferation, and this ability is dose-dependent. Intravenous administration of a cell freezing medium, therapeutic dose of cASCs (2 × 106 live cells/kg), and five times higher dose of cASCs showed no significant side effects in two dogs. Microscopic tissue lesions were limited to only mild, non-specific changes. There were no signs of malignancy. The results of the study indicate that cASCs are similar to hASCs and are safe for therapeutic applications in a canine model. The proposed methodology for ASC preparation on a non-routine basis, which includes individually optimised cell culture conditions and offers risk-adapted treatment, could be used for future personalised off-the-shelf therapies, for example, in myocardial infarction or stroke