Measurement Strategies for Geoelectrical Tomography: Specialized Techniques for Multichannel Instruments

How to select which measurements to make during a geoelectrical resistivity survey has been an active field of research for decades. Despite this techniques for optimizing the measurement sequences so as to take full advantage of the multichannel capabilities of modern state of the art equipment are scarce. In this thesis special attention is directed towards full usage of the measuring system's multichannel capabilities. The thesis also aims to be an introduction to the field of geoelectrical tomography for the unfamiliar reader, in particular the concept of the sensitivity of a measurement is fully derived. The methods presented in this article are all relying on sampling the sensitivity function and from these samples design a set of measurements. The methods discussed will largely rely on selecting measurements that are as 'different' from each other as possible - where the difference is measured in either the correlation of the sensitivities or the distance of the sensitivities' mass centers. These new methods are later adapted for multichannel use, after a presentation of how the multichannel system works. The resulting sets of measurements are tested on a simple model consisting of resistive prisms buried in otherwise homogeneous ground. The simulated measurements and the inversion of these measurements are done with the third party programs res2dmod and res2dinv respectively. From these simulation it is concluded that the methods optimized for multichannel successfully schedules close to the maximum number of measurements per current injection without losing much performance compared to their single channel counterpart. Field measurements with a multichannel-optimized protocol is also presented and compared with a reference protocol

Aesthetic international political economy

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The Gentle Art of Retroduction: Critical Realism, Cultural Political Economy and Critical Grounded Theory

This article, first, proposes critical grounded theory (CGT) as a way to develop systematically an array of methods and theoretical propositions into a coherent critical methodology for organization studies (and beyond). Second, it demonstrates CGT’s usefulness through a case study of competing recovery projects from the Icelandic financial crisis. CGT is developed in engagement with the emerging paradigm of cultural political economy (CPE) and its preferred method of critical discourse analysis (CDA). CPE analyses the evolution of ‘economic imaginaries’ in both their structural/material and semiotic/discursive dimensions. This requires a critical realist, multi-dimensional research strategy which emphasizes ethnographic methods and substantial theoretical and historical work. The proposed methodology of CGT enables a retroductive research process that combines deductive theoretical deskwork with inductive fieldwork enabled by grounded theory tools to analyse organizational process, stability and change

Self-sufficiency of fuels for tractive power in small-scale organic agriculture

Small-scale organic agriculture, with integrated crop and animal production has the potential of producing significant amounts of food. Self-sufficiency of fuel for farm work has been investigated closer in this study, based on a set of prerequisites that were identified as important for future sustainability. An implication of the study is that low-tech solutions are more likely to be renewable in the production. Fuel production for farm work at the farm also facilitates nutrient recycling. Draught horse power turned out to be comparable with other biofuels, and in a system perspective even more efficient in some cases. For ensuring a sustained food production social solutions for cleaning and recycling human excreta must be developed. Low-input small-scale agriculture may in theory contribute to solving several environmental challenges. The real challenges are social: how to distribute food and how to have enough labour in agriculture to manage cropping systems that gives a diverse production

Local treatment of a bone graft by soaking in zoledronic acid inhibits bone resorption and bone formation. A bone chamber study in rats.

ABSTRACT: BACKGROUND: Bone grafts are frequently used in orthopaedic surgery. Graft remodelling is advantageous but can occur too quickly, and premature bone resorption might lead to decreased mechanical integrity of the graft. Bisphosphonates delay osteoclastic bone resorption but may also impair formation of new bone. We hypothesize that these effects are dose dependent. In the present study we evaluate different ways of applying bisphosphonates locally to the graft in a bone chamber model, and compare that with systemic treatment. METHODS: Cancellous bone grafts were placed in titanium chambers and implanted in the tibia of 50 male rats, randomly divided into five groups. The first group served as negative control and the grafts were rinsed in saline before implantation. In the second and third groups, the grafts were soaked in a zoledronic acid solution (0.5 mg/ml) for 5 seconds and 10 minutes respectively before being rinsed in saline. In the fourth group, 8 μL of zoledronic acid solution (0.5 mg/ml) was pipetted onto the freeze-dried grafts without rinsing. The fifth group served as positive control and the rats were given zoledronic acid (0.1 mg/kg) systemically as a single injection two weeks after surgery. The grafts were harvested at 6 weeks and analysed with histomorphometry, evaluating the ingrowth distance of new bone into the graft as an equivalent to the anabolic osteoblast effect and the amount (bone volume/total volume; BV/TV) of remaining bone in the remodelled graft as equivalent to the catabolic osteoclast effect. RESULTS: In all chambers, almost the entire graft had been revascularized but only partly remodelled at harvest. The ingrowth distance of new bone into the graft was lower in grafts soaked in zoledronic acid for 10 minutes compared to control (p = 0.007). In all groups receiving zoledronic acid, the BV/TV was higher compared to control. CONCLUSIONS: This study found a strong inhibitory effect on bone resorption by bisphosphonates but also a limited inhibition of the ingrowth of new bone. Local treatment at surgery resulted in stronger inhibition of both resorption and bone formation compared to systemic treatment

ACUTE PANCREATITIS in HELSINKI in 2016-2018 : INCIDENCE, ETIOLOGY and RISK FACTORS-analysis of 1378 acute pancreatitis episodes in a Finnish normal population

Objectives Updated population-based studies on acute pancreatitis (AP) in Finland are lacking. Our aim was to evaluate the current data for AP in Helsinki. Materials and methods We performed an electronic health care records (EHRs) search on AP patients treated at Helsinki University Hospital between the years 2016 - 2018. Incidence was calculated, etiological and potential risk factors, as well as severity of AP were documented and analyzed. Results Between 2016 and 2018 we found 1378 AP episodes on 1084 patients, 35% of the patients had several AP episodes, i.e., recurrent AP (RAP). The domicile-adjusted incidence was 42.2/100 000. 47% of the patients had alcohol etiology (59% men, 27% women) and 23% had biliary etiology, 21% were idiopathic and 2.9% were post-ERCP pancreatitis. 13.1% of the patients had passed at the end of September 2021. 45% of the patients were currently smoking, 11% were ex-smokers, and the highest percentage of smokers was in the group of alcohol-caused AP with 74% ever-smokers. Biliary AP had the highest amount of overweight patients. 24% of the patients used anticoagulation (AC) medication, and the percentage was significantly higher with idiopathic AP (48%). RAP, female sex and normal BMI associated with a mild form of AP. Conclusions Incidence of AP and the percentage of alcohol etiology are lower than earlier reported for Finland although still higher than in other Nordic countries. Smoking and the use of AC medication associate with AP.Peer reviewe

Intermodulated optogalvanic spectroscopy - a comparison with other high-resolution techniques

A comparison of intermodulated fluorescence spectroscopy, intermodulated optogalvanic spectroscopy, POLINEX (POLarization INtermodulated EXcitation) spectroscopy and polarization spectroscopy used in Doppler-free spectroscopy on hollow cathode discharges is made, mainly based on experiments performed on the 2p53s 3P2 - 2p53p 3P1 transition in Ne at λ=5882 Å and the 4d55s 5S2 - 4d55p 5P3 transition in Mo at λ=5506 Å. Some general aspects regarding the hollow cathode as a tool in high-resolution laser spectroscopy are also briefly discussed