Vaihe- ja amplitudikorrelaatiot vastasyntyneen EEG:ssa

In this thesis, the aim was to study the phase and amplitude correlations within neonatal electroencephalography (EEG) measurements. Premature birth can cause hindrances and changes in the functional connectivity of the brain, which can lead to serious neurological disorders later in life. The dataset consists of measurements from 113 babies: 67 born fullterm and 46 born preterm. The EEG measurements were done at the term-equivalent age in order to compare the phase and amplitude correlations between the two groups. Three different synchrony features were calculated from the data, in order to represent the different types of phase and amplitude correlations within the newborn brain. The main focus of this thesis is on the differences in functional connectivity between the two groups, but it is also studied how functional connectivity is located in the brain within the groups, and how the synchrony features are correlated with conceptional age, with each other and with the neurological scores C1 and C2. The neurological scores evaluate the motor and sensory development of a baby at birth. As a result of all these tests there are clear differences between the two groups, which show that the connections in the brain do not all develop at the same time and the development in the preterms might be slightly delayed. The results of this thesis also show that synchrony features might have some predictive value in regards to cognitive outcome.Tässä diplomityössä tutkittiin vastasyntyneen elektroenkefalogrammin (EEG) vaihe- ja amplitudikorrelaatioita. Ennenaikainen syntymä voi aiheuttaa komplikaatioita ja muutoksia aivojen funktionaalisessa konnektiivisuudessa, mikä voi johtaa vakaviin neurologisiin häiriöihin myöhemmin elämässä. Tutkimuksessa käytetty aineisto koostuu 113:n vauvan EEG-mittauksista: 67 täysiaikaisena syntynyttä ja 46 ennenaikaisesti syntynyttä. EEG-mittaukset suoritettiin täysiaikaisuutta vastaavassa iässä, jotta vaihe- ja amplitudikorrelaatiot ovat vertailukelpoisia ryhmien välillä. Aineistosta laskettiin kolme erilaista synkroniamittaria, jotka kuvaavat vastasyntyneen aivoissa esiintyviä erilaisia vaihe- ja amplitudikorrelaatioita. Diplomityön ensisijaisena tavoitteena oli tutkia edellä mainittujen kahden ryhmän välisiä eroja aivojen funktionaalisessa konnektiivisuudessa. Työssä tutkitaan myös, kuinka funktionaalinen konnektiivisuus on jakautunut aivoissa ryhmien sisäisesti sekä kuinka synkroniamittarit ovat korreloituneet iän kanssa, keskenään sekä neurologisten mittarien C1 ja C2 kanssa. Mittarit C1 ja C2 arvioivat vauvan motorista ja sensorista kehitystä syntymän hetkellä. Kaikki nämä tutkimukset osoittavat, että ryhmien välillä on selkeitä eroja, mistä havaitaan, että yhteydet aivoissa eivät kehity kaikkialla samaan aikaan ja että keskosina syntyneiden aivojen kehitys on mahdollisesti hieman myöhästynyt. Tuloksista havaitaan myös, että synkroniamittareista saattaa olla hyötyä vauvan kognitiivisen kehityksen ennustamisessa

Sources of variability in expiratory flow profiles during sleep in healthy young children

Standard lung function tests are not feasible in young children, but recent studies show that the variability of expiratory tidal breathing flow-volume (TBFV) curves during sleep is a potential indirect marker of lower airway obstruction. However, the neurophysiological sources of the TBFV variability in normal subjects has not been established. We investigated sleep stages and body position changes as potential sources for the TBFV curve variability. Simultaneous impedance pneumography (IP), polysomnography (PSG) and video recordings were done in 20 children aged 1.4-6.9 years without significant respiratory disorders during sleep. The early part of expiratory TBFV curves are less variable between cycles of REM than NREM sleep. However, within individual sleep cycles, TBFV curves during N3 are the least variable. The differences in TBFV curve shapes between sleep stages are the main source of overnight variability in TBFV curves and the changes in body position have a lesser impact.Peer reviewe

Expiratory variability index is associated with asthma risk, wheeze and lung function in infants with recurrent respiratory symptoms

Non peer reviewe

60Co in Cast Steel Matrix: a European Interlaboratory Comparison for the Characterisation of New Activity Standards for Calibration of Gamma-ray Spectrometers in Metallurgy

International audience; Two series of activity standards of Co-60 in cast steel matrix, developed for the calibration of gamma-ray spectrometry systems in the metallurgical sector, were characterised using a European interlaboratory comparison among twelve National Metrology Institutes and one international organisation. The first standard, consisting of 14 disc shaped samples, was cast from steel contaminated during production ("originally"), and the second, consisting of 15 similar discs, from artificially-contaminated ("spiked") steel. The reference activity concentrations of Co-60 in the cast steel standards were (1.077 +/- 0.019) Bq g(-1) on 1 January 2013 12h00 UT and (1.483 +/- 0.022) Bq g(-1) on 1 June 2013 12h00 UT, respectively

Development of alkali activated cements and concrete mixture design with high volumes of red mud

Dedicated cement compositions were formulated to enable the incorporation of large volume fractions of red mud in alkali activated cements, taking into account the role of the aluminosilicate phase in the processes of hydration and hardening. High volume red mud alkali activated cements were synthesized using a proper combination of red mud, low basic aluminosilicate compounds with a glass phase (blast-furnace slag) and additives selected from high-basic Ca-containing cements with a crystalline structure (Portland cement). Compressive strength of the cements under study is 30-60 MPa (tested in mortar). The microstructure of the hardened cement paste and the role of red mud in the structure formation process were investigated. In addition to the use of red mud in cement, its use as an aggregate in concrete was studied to enable the use of larger quantities in the final concrete. In concrete road bases, the use of red mud can reach even 90 % by mass. Since enhanced concentrations of naturally occurring radionuclides can be present in red mud this aspect was investigated to make sure that these materials are safe to use from a radiological point of view.JRC.G.2-Standards for Nuclear Safety, Security and Safeguard