Stress intensity factor of wood from crack-tip displacement fields obtained from digital image processing

Abstract

Thinning intensity and growth of mixed spruce-birch stands on drained peatlands in Finland

Abstract

Timing and intensity of precommercial thinning and their effects on the first commercial thinning in Scots pine stands

Abstract

Mobile robot localization using sonar ranging and wlan intensity maps

 Main goal of this thesis was to implement a localization system which uses sonars and WLAN intensity maps to localize an indoor mobile robot. A probabilistic localization method, Monte Carlo Localization is used in localization. Also the theory behind probabilistic localization is explained. Two main problems in mobile robotics, path tracking and global localization, are solved in this thesis. Implemented system can achieve acceptable performance in path tracking. Global localization using WLAN received signal strength information is shown to provide good results, which can be used to localize the robot accurately, but also some bad results, which are no use when trying to localize the robot to the correct place. Main goal of solving ambiguity in office like environment is achieved in many test cases.

Pain-evoked alterations on gingival blood flow and gingival crevicular fluid (GCF) neuropeptide SP and collagenase-2 (MMP-8) levels

Previous studies have demonstrated that clinical pulpal pain can induce the expression of pro-inflammatory neuropeptides in the adjacent gingival crevice fluid (GCF). Vasoactive agents such as substance P (SP) are known to contribute to the inflammatory type of pain and are associated with increased blood flow. More recent animal studies have shown that application of capsaicin on alveolar mucosa provokes pain and neurogenic vasodilatation in the adjacent gingiva. Pain-associated inflammatory reactions may initiate expression of several pro- and anti-inflammatory mediators. Collagenase-2 (MMP-8) has been considered to be the major destructive protease, especially in the periodontitis-affected gingival crevice fluid (GCF). MMP-8 originates mostly from neutrophil leukocytes, the first line of defence cells that exist abundantly in GCF, especially in inflammation. With this background, we wished to clarify the spatial extensions and differences between tooth-pain stimulation and capsaicin-induced neurogenic vasodilatation in human gingiva. Experiments were carried out to study whether tooth stimulation and capsaicin stimulation of alveolar mucosa would induce changes in GCF MMP-8 levels and whether tooth stimulation would release neuropeptide SP in GCF. The experiments were carried out on healthy human volunteers. During the experiments, moderate and high intensity painful tooth stimulation was performed by a constant current tooth stimulator. Moderate tooth stimulation activates A-delta fibres, while high stimulation also activates C-fibres. Painful stimulation of the gingiva was achieved by topical application of capsaicin-moistened filter paper on the mucosal surface. Capsaicin is known to activate selectively nociceptive C-fibres of stimulated tissue. Pain-evoked vasoactive changes in gingivomucosal tissues were mapped by laser Doppler imaging (LDI), which is a sophisticated and non-invasive method for studying e.g. spatial and temporal characteristics of pain- and inflammation-evoked blood flow changes in gingivomucosal tissues. Pain-evoked release of MMP-8 in GCF samples was studied by immunofluorometric assay (IFMA) and Western immunoblotting. The SP levels in GCF were analysed by Enzyme immunoassay (EIA). During the experiments, subjective stimulus-evoked pain responses were determined by a visual analogue pain scale. Unilateral stimulation of alveolar mucosa and attached gingiva by capsaicin evoked a distinct neurogenic vasodilatation in the ipsilateral gingiva, which attenuated rapidly at the midline. Capsaicin stimulation of alveolar mucosa provoked clear inflammatory reactions. In contrast to capsaicin stimuli, tooth stimulation produced symmetrical vasodilatations bilaterally in the gingiva. The ipsilateral responses were significantly smaller during tooth stimulation than during capsaicin stimuli. The current finding – that tooth stimulation evokes bilateral vasodilatation while capsaicin stimulation of the gingiva mainly produces unilateral vasodilatation – emphasises the usefulness of LDI in clarifying spatial features of neurogenic vasoactive changes in the intra-oral tissues. Capsaicin stimulation of the alveolar mucosa induced significant elevations in MMP-8 levels and activation in GCF of the adjacent teeth. During the experiments, no marked changes occurred in MMP-8 levels in the GCF of distantly located teeth. Painful stimulation of the upper incisor provoked elevations in GCF MMP-8 and SP levels of the stimulated tooth. The GCF MMP-8 and SP levels of the non-stimulated teeth were not changed. These results suggest that capsaicin-induced inflammatory reactions in gingivomucosal tissues do not cross the midline in the anterior maxilla. The enhanced reaction found during stimulation of alveolar mucosa indicates that alveolar mucosa is more sensitive to chemical irritants than the attached gingiva. Analysis of these data suggests that capsaicin-evoked neurogenic inflammation in the gingiva can trigger the expression and activation of MMP-8 in GCF of the adjacent teeth. In this study, it is concluded that experimental tooth pain at C-fibre intensity can induce local elevations in MMP-8 and SP levels in GCF. Depending on the role of MMP-8 in inflammation, in addition to surrogated tissue destruction, the elevated MMP-8 in GCF may also reflect accelerated local defensive and anti-inflammatory reactions.

Hypoxia-associated biomarkers in rectal cancer treated by preoperative radiotherapy or chemoradiotherapy

Hypoksiaan liittyvät biologiset merkkiaineet leikkausta edeltävällä sädehoidolla tai kemosädehoidolla hoidetussa peräsuolisyövässä Peräsuolensyöpä on yleinen pahanlaatuinen kasvain. Leikkausta edeltävä sädehoito annetaan yleensä T3-T4-kasvaimille. Tutkimuksella pyrittiin selvittämään, voidaanko kasvaimen hapenpuutteeseen liittyvillä biologisilla merkkiaineilla arvioida peräsuolisyövän ennustetta leikkausta edeltävän sädehoidon tai kemosädehoidon jälkeen. Tällaisia merkkiaineita ovat hapenpuutteen vaikutuksesta aktivoituva HIF-1alfa hiilihappoanhydraasi IX (CA IX), sokerin kuljetukseen solussa osallistuva GLUT-1 sekä solun tukirankaproteiini ezrin. Tutkimukseen otettiin 178 potilasta, jotka olivat saaneet ennen leikkausta lyhyen (n=77) tai pitkän sädehoidon (n=10), pitkän sädehoidon ja solunsalpaajahoidon (n=37) tai ei mitään hoitoa (n=54). Lisäksi osalta leikkausta edeltävää sädehoitoa saaneelta potilaalta tutkittiin hoitoja edeltävät, diagnostiset näytteet (n=80). Tutkimuksessa käytettiin immunehistokemiallisia värjäysmenetelmiä. Kasvaimen regressiota (TRG) arvioitiin pitkän sädehoidon jälkeisistä näytteistä. Leikkausnäytteissä negatiivinen/heikko CA IX intensiteetti liittyi sekä pidempään tautispesifiseen (p=0.034) että tautivapaaseen elinaikaan (p=0.003) ja pitkän sädehoidon jälkeen HIF-1alfa-negatiivisuus pidempään tautispesifiseen (p=0.001) sekä negatiivinen/heikko GLUT-1 pidempään tautivapaaseen elinaikaan (p=0.066). Voimakas ezrin-ilmentymä diagnostisissa näytteissä liittyi lyhyempään tautivapaaseen ja tautispesifiseen (p=0.027 ja p=0.002) ennusteeseen. Monimuuttuja-analyysissä vahva CA IX intensiteetti leikkausnäytteissä ennusti itsenäisesti huonompaa tautivapaata ja tautispesifistä selviytymistä. Erinomainen TRG liittyi negatiiviseen/heikkoon CA IX- (p=0.057), ezrin- (p=0.012) ja GLUT-1 -ilmentymään (p=0.013) leikkausnäytteissä. Kun kaikki neljä merkkiainetta analysoitiin yhdessä monimuuttuja-analyysissä, CA IX intensiteetti leikkausnäytteissä ennusti itsenäisesti tautispesifistä elinaikaa. Voimakas CA IX-ilmentymä leikkausnäytteissä ja positiivinen HIF-1alfa- ja vahva GLUT-1-ilmentymä pitkän sädehoidon jälkeisissä leikkausnäytteissä sekä vahva ezrin-ilmentymä diagnostisissa näytteissä liittyivät epäsuotuisaan ennusteeseen. Monimuuttujaanalyysissä kohtalainen/voimakas CA IX intensiteetti leikkausnäytteissä ennusti itsenäisesti huonompaa tautivapaata ja tautispesifistä elinaikaa. CA IX on vahva biologinen merkkiaine peräsuolisyövässä.

The Possibilities and Dosimetric Limitations of MLC-Based Intensity-Modulated Radiotherapy Delivery and Optimization Techniques

The use of intensity-modulated radiotherapy (IMRT) has increased extensively in the modern radiotherapy (RT) treatments over the past two decades. Radiation dose distributions can be delivered with higher conformality with IMRT when compared to the conventional 3D-conformal radiotherapy (3D-CRT). Higher conformality and target coverage increases the probability of tumour control and decreases the normal tissue complications. The primary goal of this work is to improve and evaluate the accuracy, efficiency and delivery techniques of RT treatments by using IMRT. This study evaluated the dosimetric limitations and possibilities of IMRT in small (treatments of head-and-neck, prostate and lung cancer) and large volumes (primitive neuroectodermal tumours). The dose coverage of target volumes and the sparing of critical organs were increased with IMRT when compared to 3D-CRT. The developed split field IMRT technique was found to be safe and accurate method in craniospinal irradiations. By using IMRT in simultaneous integrated boosting of biologically defined target volumes of localized prostate cancer high doses were achievable with only small increase in the treatment complexity. Biological plan optimization increased the probability of uncomplicated control on average by 28% when compared to standard IMRT delivery. Unfortunately IMRT carries also some drawbacks. In IMRT the beam modulation is realized by splitting a large radiation field to small apertures. The smaller the beam apertures are the larger the rebuild-up and rebuild-down effects are at the tissue interfaces. The limitations to use IMRT with small apertures in the treatments of small lung tumours were investigated with dosimetric film measurements. The results confirmed that the peripheral doses of the small lung tumours were decreased as the effective field size was decreased. The studied calculation algorithms were not able to model the dose deficiency of the tumours accurately. The use of small sliding window apertures of 2 mm and 4 mm decreased the tumour peripheral dose by 6% when compared to 3D-CRT treatment plan. A direct aperture based optimization (DABO) technique was examined as a solution to decrease the treatment complexity. The DABO IMRT technique was able to achieve treatment plans equivalent with the conventional IMRT fluence based optimization techniques in the concave head-and-neck target volumes. With DABO the effective field sizes were increased and the number of MUs was reduced with a factor of two. The optimality of a treatment plan and the therapeutic ratio can be further enhanced by using dose painting based on regional radiosensitivities imaged with functional imaging methods.