Cumulative Costs of Caries Prevention and Treatment in Children - with Special Reference to Work Division and Cohort Effect

Lapsen karieshoidon kustannuskertymän muutokset ja karieshoidon toimintakäytäntöjen yhteys kustannuksiin Tutkimuksen tavoitteena oli mitata terveyskeskuksessa hoidettavien lasten karieshoidon kumulatiivisia kustannuksia ja verrata niitä kahden erilaisen toimintatavan välillä. Lisäksi tarkasteltiin lasten hampaiden terveyttä. Tutkimus tehtiin julkisen palvelutuottajan näkökulmasta. Tutkimusaineisto kerättiin Kemin ja Tornion terveyskeskusten suun terveydenhuollon potilaskertomuksista. Kemin kohortit 1980, 1983 ja 1986 (n = 600) ja Tornion kohortit 1980 ja 1992 (n = 400) edustivat perinteistä ja Kemin kohortit 1989, 1992 ja 1995 (n = 600) uutta toimintatapaa työnjaon ja ehkäisyn ajoituksen suhteen. Kohortteja ja kaupunkeja verrattiin hampaiden terveyden (dmft/DMFT = 0 ja dmft ja DMFT keskiarvot 5 ja 12 vuoden iässä) ja voimavarojen käytön suhteen. Panoskäyttö johdettiin käyntimäärien avulla laskennallisen työajan kautta. Kustannuskertymät muodostettiin käyttämällä henkilöstömenoista laskettuja suorittajakohtaisia yksikkökustannuksia. Panoskäytön ja yksikkökustannusten kautta muodostettiin kustannuskertymät. Kustannusten ja terveysvaikutusten suhteita arvioitiin kustannus-vaikuttavuusanalyysissä. Suuhygienistien työpanosta hyödyntävällä varhaisen ehkäisyn toimintamallilla saavutettiin vähäisemmin kustannuksin alle kouluiässä parempi ja kouluiässä yhtä hyvä hammasterveys kuin perinteisellä, enemmän hammaslääkärien työpanokseen perustuvalla tavalla. Karieksen hoitoon liittyvien käyntien määrä oli nuorimmissa syntymävuosikohorteissa pienempi kuin vanhimmissa kohorteissa. Käynnit hammaslääkärissä vähenivät eniten. Toimintatavalla oli merkittävä vaikutus lapsen karieshoidon kokonaiskustannuksiin. Herkkyysanalyysin mukaan karieshoidon kustannukset olivat työnjakoa hyödyntämällä kolmanneksen pienemmät, kuin jos hoidon suorittajana olisi ollut ainoastaan hammaslääkäri-hoitaja työpari. Lasten karieshoidon kustannusvaikuttavuus kohentui molemmissa terveyskeskuksissa nuoremmissa kohorteissa vanhempiin verrattuna. Suun terveydenhuollon potilaskertomuksia olisi hyödynnettävä toiminnan kehittämisessä. Varhaisen ehkäisyn avulla voitaisiin kaikkien suun terveydenhuollon ammattihenkilöiden työpanos kohdentaa kustannustehokkaasti.

Feature selection using Fuzzy Entropy measures with Yu's Similarity measure

In this study, feature selection in classification based problems is highlighted. The role of feature selection methods is to select important features by discarding redundant and irrelevant features in the data set, we investigated this case by using fuzzy entropy measures. We developed fuzzy entropy based feature selection method using Yu's similarity and test this using similarity classifier. As the similarity classifier we used Yu's similarity, we tested our similarity on the real world data set which is dermatological data set. By performing feature selection based on fuzzy entropy measures before classification on our data set the empirical results were very promising, the highest classification accuracy of 98.83% was achieved when testing our similarity measure to the data set. The achieved results were then compared with some other results previously obtained using different similarity classifiers, the obtained results show better accuracy than the one achieved before. The used methods helped to reduce the dimensionality of the used data set, to speed up the computation time of a learning algorithm and therefore have simplified the classification task

The Effects of Anesthetic Induced Loss of Consciousness on Quantitative Electroen Cephalogram, and Bispectral and Spectral Entropy Indices. Studies on Healthy Male

Changes in the electroencephalography (EEG) signal have been used to study the effects of anesthetic agents on the brain function. Several commercial EEG based anesthesia depth monitors have been developed to measure the level of the hypnotic component of anesthesia. Specific anesthetic related changes can be seen in the EEG, but still it remains difficult to determine whether the subject is consciousness or not during anesthesia. EEG reactivity to external stimuli may be seen in unconsciousness subjects, in anesthesia or even in coma. Changes in regional cerebral blood flow, which can be measured with positron emission tomography (PET), can be used as a surrogate for changes in neuronal activity. The aim of this study was to investigate the effects of dexmedetomidine, propofol, sevoflurane and xenon on the EEG and the behavior of two commercial anesthesia depth monitors, Bispectral Index (BIS) and Entropy. Slowly escalating drug concentrations were used with dexmedetomidine, propofol and sevoflurane. EEG reactivity at clinically determined similar level of consciousness was studied and the performance of BIS and Entropy in differentiating consciousness form unconsciousness was evaluated. Changes in brain activity during emergence from dexmedetomidine and propofol induced unconsciousness were studied using PET imaging. Additionally, the effects of normobaric hyperoxia, induced during denitrogenation prior to xenon anesthesia induction, on the EEG were studied. Dexmedetomidine and propofol caused increases in the low frequency, high amplitude (delta 0.5-4 Hz and theta 4.1-8 Hz) EEG activity during stepwise increased drug concentrations from the awake state to unconsciousness. With sevoflurane, an increase in delta activity was also seen, and an increase in alpha- slow beta (8.1-15 Hz) band power was seen in both propofol and sevoflurane. EEG reactivity to a verbal command in the unconsciousness state was best retained with propofol, and almost disappeared with sevoflurane. The ability of BIS and Entropy to differentiate consciousness from unconsciousness was poor. At the emergence from dexmedetomidine and propofol induced unconsciousness, activation was detected in deep brain structures, but not within the cortex. In xenon anesthesia, EEG band powers increased in delta, theta and alpha (8-12Hz) frequencies. In steady state xenon anesthesia, BIS and Entropy indices were low and these monitors seemed to work well in xenon anesthesia. Normobaric hyperoxia alone did not cause changes in the EEG. All of these results are based on studies in healthy volunteers and their application to clinical practice should be considered carefully.

Modeling of residual stresses and distortion due to welding in fillet welds

Welding has a growing role in modern world manufacturing. Welding joints are extensively used from pipes to aerospace industries. Prediction of welding residual stresses and distortions is necessary for accurate evaluation of fillet welds in relation to design and safety conditions. Residual stresses may be beneficial or detrimental, depending whether they are tensile or compressive and the loading. They directly affect the fatigue life of the weld by impacting crack growth rate. Beside theoretical background of residual stresses this study calculates residual stresses and deformations due to localized heating by welding process and subsequent rapid cooling in fillet welds. Validated methods are required for this purpose due to complexity of process, localized heating, temperature dependence of material properties and heat source. In this research both empirical and simulation methods were used for the analysis of welded joints. Finite element simulation has become a popular tool of prediction of welding residual stresses and distortion. Three different cases with and without preload have been modeled during this study. Thermal heat load set is used by calculating heat flux from the given heat input energy. First the linear and then nonlinear material behavior model is modeled for calculation of residual stresses. Experimental work is done to calculate the stresses empirically. The results from both the methods are compared to check their reliability. Residual stresses can have a significant effect on fatigue performance of the welded joints made of high strength steel. Both initial residual stress state and subsequent residual stress relaxation need to be considered for accurate description of fatigue behavior. Tensile residual stresses are detrimental and will reduce the fatigue life and compressive residual stresses will increase it. The residual stresses follow the yield strength of base or filler material and the components made of high strength steel are typically thin, where the role of distortion is emphasizing.

On-line determination of residual collector concentration in flotation process

Valuable minerals can be recovered by using froth flotation. This is a widely used separation technique in mineral processing. In a flotation cell hydrophobic particles attach on air bubbles dispersed in the slurry and rise on the top of the cell. Valuable particles are made hydrophobic by adding collector chemicals in the slurry. With the help of a frother reagent a stable froth forms on the top of the cell and the froth with valuable minerals, i.e. the concentrate, can be removed for further processing. Normally the collector is dosed on the basis of the feed rate of the flotation circuit and the head grade of the valuable metal. However, also the mineral composition of the ore affects the consumption of the collector, i.e. how much is adsorbed on the mineral surfaces. Therefore it is worth monitoring the residual collector concentration in the flotation tailings. Excess usage of collector causes unnecessary costs and may even disturb the process. In the literature part of the Master’s thesis the basics of flotation process and collector chemicals are introduced. Capillary electrophoresis (CE), an analytical technique suitable for detecting collector chemicals, is also reviewed. In the experimental part of the thesis the development of an on-line CE method for monitoring the concentration of collector chemicals in a flotation process and the results of a measurement campaign are presented. It was possible to determine the quality and quantity of collector chemicals in nickel flotation tailings at a concentrator plant with the developed on-line CE method. Sodium ethyl xanthate and sodium isopropyl xanthate residuals were found in the tailings and slight correlation between the measured concentrations and the dosage amounts could be seen.