Risk factors, surgical outcome, and quality of life in patients with cranial or spinal meningioma

Meningiomas comprise approximately 30-38% of all cranial tumours and represent the largest group of primary intracranial and intraspinal tumours. Gliomas, of any grade, account for approximately 28% and glioblastomas 15% of the cranial tumours, as comparison. Roughly 2% of all meningiomas are spinal, constituting 25-45% of all spinal intradural tumours. Despite extensive research in this field, there is still no consensus on the best strategies for surgical resection, follow-up, and supplementary treatments. Risk factors for meningioma development and factors affecting health-related quality of life (HRQoL) and return to work for this heterogenous patient group are poorly understood. This thesis aimed to study population-based cohorts with cranial and spinal meningiomas to bring greater clarity to some of these questions. In study I, a 25-year follow-up of patients with parasagittal meningiomas was conducted, revealing that radical resection was of great importance to reduce recurrence, morbidity, and tumour mortality. Furthermore, more than 15 years of radiological follow-up was necessary to detect late recurrences. Study II evaluated the surgical results for meningiomas that engaged major venous sinuses, demonstrating that microscopic radicality was difficult to achieve and that supplementary stereotactic gamma knife radiosurgery was beneficial and should be considered as an adjuvant treatment directly after surgery. In study III, a large epidemiologic survey of a female Swedish population was conducted to understand a possible connection between sex hormones and risk of developing a meningioma during and after pregnancy. Contradictory to our hypothesis, there was no increased risk for diagnosing a meningioma during pregnancy or 1-year postpartum, thus indicating that pregnancy should not be seen as a risk factor for meningioma. Study IV on spinal meningiomas revealed that surgery was associated with a significant improvement in neurological function independently predicted by a shorter time from diagnosis to surgery and the degree of spinal cord compression. Elderly patients benefitted to same degree as non-elderly patients from surgical intervention without increased complications. Study V analysed the HRQoL and frequency of return to work among patients operated on for a spinal meningioma. Ninety-six percent of patients were satisfied with the surgical results. Despite a high median age at surgery, and unlike cranial meningiomas or lumbar spinal stenosis, the HRQoL at long-term follow-up was equivalent to a matched sample of the general population. All patients working before their operation returned to work postoperatively, most of them within three months. Study VI evaluated long-term follow-up and HRQoL for patients treated for cranial WHO grades 2 and 3 meningiomas. Despite dismal prognoses with 93% of the mortality attributed to meningiomas, a large subgroup comprising both grades 2 and 3 was alive at 10 years follow- up after one operation or operations supplemented with gamma knife radiosurgery, showing a longer overall survival compared to previous reports. In contrast, fractionated radiotherapy and chemotherapy had little benefit when introduced for recurrent or progressive disease. The surviving meningioma patients showed HRQoL measurements comparable to those of the general population, except for significantly more anxiety and depression. Despite suffering from a chronic disease and in contrast to previous reports, all patients who were working before surgery returned to work after surgery. In conclusion, based on the findings of this thesis, we recommend long-term radiological follow-up and supplementary gamma knife radiosurgery for tumour control of cranial meningiomas. The effects of sex hormones are multi-faceted and require further in-depth studies. Spinal meningiomas should be treated rapidly after diagnosis for all ages to promote excellent neurological outcomes and HRQoL measures. Despite the chronic nature of the disease, subgroups of WHO grades 2 and 3 meningiomas can yield long-term outcomes and HRQoL measures

A lower bound for the pigeonhole principle in tree-like Resolution by asymmetric Prover-Delayer games

In this note we show that the asymmetric Prover–Delayer game developed in Beyersdorff et al. (2010) [2] for Parameterized Resolution is also applicable to other tree-like proof systems. In particular, we use this asymmetric Prover–Delayer game to show a lower bound of the form 2Ω(nlogn) for the pigeonhole principle in tree-like Resolution. This gives a new and simpler proof of the same lower bound established by Iwama and Miyazaki (1999) [7] and Dantchev and Riis (2001) [5]

Biltrafikens påverkan på lavfloran

Många forskare har sett att luftens föroreningar ackumuleras i bålen hos epifytiska lavar och påverkar dem. Detta gör att utifrån vilka lavar som lever i ett område går det att dra slutsatser om hur påverkad miljön är av luftföroreningar. Utifrån detta faktum har busk- och bladlavar inventerats längs en sträcka av E4:an norr om Gävle. I undersökningen inventerades 36 tallar och 6 björkar längs med E4:an och 18 tallar och 4 björkar i ett referensområde några kilometer från E4:an. På dessa 64 träd och hittades 15 olika lavarter och en alg. Med de insamlade data som utgångspunkt räknas olika index fram för att jämföra undersökningsområdet med referensområdet. De index som använts i föreliggande rapport är medelkänslighetsvärde, kvävetal och skogsytans lavkvalitetsindex. Resultaten av studien visar på en signifikant skillnad i medelkänslighetsvärde och i skogsytans lavkvalitetesindex med högst värden i referensområdet. Däremot visar resultatet av kvävetal ingen signifikant skillnad mellan undersökningsområdet och referensområdet. Detta indikerar att lavfloran längs med E4:an är negativt påverkad av luftföroreningar orsakad av trafiken. Studien visar inte vilka föroreningar som ligger bakom skillnaderna.Many scientists have found that air pollutants have been accumulated in epiphytic lichens and affect them. This means that from which type of lichens that live in an area it is possible to draw conclusions about how the environment is influenced by air pollution. Based on these facts, the lichens have been inventoried along a stretch of highway E4 north of Gävle. The study includes 36 pines and 6 birches along the highway E4 and 18 pines and 4 birches in a reference area a few kilometers from the E4 that was inventoried for lichens. On these 64 trees 15 different lichens and one algae was found. With the collected data as a base various indexes were calculated to compare the survey area with the reference area. The indices used in this report are “medelkänslighetsvärde”, “kvävetal” och ”skogsytans lavkvalitetsindex”. The results of this study show a significant difference in “medelkänslighetsvärde” and “skogsytans lavkvalitetesindex” with maximum values in the reference area. However, the results of “kvävetal” show no significant difference between the survey area and the reference area. This indicates that lichens flora along the highway is negatively affected by air pollution caused by traffic. The study does not show that the pollution is the factor behind the differences

Barnmorskors upplevelser, inställningar och tankar kring valet av förlossningsställningar.

Syftet med studien var att belysa barnmorskors upplevelser, inställningar och tankar kring olika förlossningsställningar. Totalt utfördes 16 individuella öppna intervjuer med förlossningsbarnmorskor. Innehållsanalys genomfördes. Tre huvudkategorier kunde urskiljas i resultatet: Lyhördhet för att tillgodose kvinnans önskemål och autonomi, Barnmorskans val av förlossningsställning samt Formandet av barnmorskan som individ. Fram till krystskedet har barnmorskorna liknande resonemang. Vikt läggs vid att möta kvinnans önskemål. I krystskedet skiljer sig barnmorskornas upplevelser åt. Åsikterna går isär om vad som kan leda till bristningar. Stort fokus ligger på att förhindra bristningar genom fullgott perinealskydd. Olika erfarenhet har betydelse för barnmorskans inställning. Forskningen är oenig inom området förlossningsställningar. Detta kan leda till att barnmorskorna tolkar studierna olika, vilket påverkar deras resonemang i deras arbete med kvinnan. Mer forskning behövs för att barnmorskorna ska arbeta enligt bästa evidens

Verifying proofs in constant depth

In this paper we initiate the study of proof systems where verification of proofs proceeds by NC circuits. We investigate the question which languages admit proof systems in this very restricted model. Formulated alternatively, we ask which languages can be enumerated by NC functions. Our results show that the answer to this problem is not determined by the complexity of the language. On the one hand, we construct NC proof systems for a variety of languages ranging from regular to NP-complete. On the other hand, we show by combinatorial methods that even easy regular languages such as Exact-OR do not admit NC proof systems. We also present a general construction of proof systems for regular languages with strongly connected NFA's

Revival of wind-powered shipping: Comparing the early-stage innovation process of an incumbent and a newcomer firm

Despite the urgency of decarbonising, the shipping sector has demonstrated a slow-paced response to climate change challenges. Some frontrunner firms are engaged in sustainability-oriented innovation processes. However, there is limited knowledge of how such processes emerge and contribute to societal sustainability transitions and what the role of technology is in companies' (re)orientation towards sustainable business models. This study contributes to filling these gaps through a comparative case study of the ongoing innovation process within an incumbent and a newcomer firm developing wind-powered energy solutions for deep-sea transportation. The study's findings bear implications for theory and practice. This paper's combination of a dynamic capabilities approach and a multi-level perspective from sustainability transitions research is a conceptual novelty, enabling an understanding of the activities involved in the (re)orientation process towards sustainable business from a company's perspective, as well as broader societal and sustainability needs.</p

Parameterized complexity of DPLL search procedures

We study the performance of DPLL algorithms on parameterized problems. In particular, we investigate how difficult it is to decide whether small solutions exist for satisfiability and other combinatorial problems. For this purpose we develop a Prover-Delayer game which models the running time of DPLL procedures and we establish an information-theoretic method to obtain lower bounds to the running time of parameterized DPLL procedures. We illustrate this technique by showing lower bounds to the parameterized pigeonhole principle and to the ordering principle. As our main application we study the DPLL procedure for the problem of deciding whether a graph has a small clique. We show that proving the absence of a k-clique requires n steps for a non-trivial distribution of graphs close to the critical threshold. For the restricted case of tree-like Parameterized Resolution, this result answers a question asked in [11] of understanding the Resolution complexity of this family of formulas

Computational design of accelerated life testing applied to frozen green beans

Three different accelerated life tests (ALT) were designed by computer simulation to investigate their practical applicability to quantify kinetics of quality loss in frozen stored foods. Heat transfer and quality degradation inside a green bean were simulated, using a spectral finite element method (SFEM), to develop pseudo-experimental data. Temperature fluctuations inside a refrigerator were simulated, by a piecewise linear stochastic differential equation, and integrated into the SFEM program. Thereafter, the simulated data was treated by non-linear regression analysis to estimate the kinetic parameters. The different ALT tests were then compared in terms of precision and accuracy. This study shows that temperature fluctuations, inside a refrigerator, influence the accuracy of the kinetic estimates, and if the temperature spectrum is used to derive kinetic estimates, it is possible to apply accurately ALT methodologies to frozen foods