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| 2. |
- Aalaei, Kataneh
(author)
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Processing and Storage stability of Skim Milk Powder : Monitoring Early and Advanced Stages of the Maillard Reaction
- 2017
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Doctoral thesis (other academic/artistic)abstract
- The non-enzymatic browning known as the Maillard reaction has been the subject of extensive investigation for decades. Studies have focused on areas such as changes in flavour, colour, texture, and the nutritional properties of food materials as a result of this reaction. However, this complex reaction between the amino acids in proteins and reducing sugars in carbohydrates, is still not fully understood, especially the reaction mechanisms and potential impacts on health.Skim milk powder (SMP), is a multi-functional and extremely popular ingredient in the food industry, and is used in infant formulas, reconstituted and fermented dairy products, frozen desserts, bakery products, coffee whiteners, and even processed meat products. Despite the apparent good stability of SMP, it is prone to the Maillard reaction and its consequences, due to its composition, as well as the application of various kinds of thermal processing, and subsequent prolonged shelf life.The aims of this work were thus to improve our understanding of the occurrence of the Maillard reaction in SMP after the application of different drying techniques, and during subsequent storage under realistic conditions, in order to be able to predict and to control the reaction. Previous studies have mainly been conducted on model food systems at the conditions applicable to processing, i.e. at temperatures above 40 ºC. In the present work, changes in two indicators of the early and advanced stages of the Maillard reaction, namely the available lysine and carboxymethyl lysine (CML), respectively, were monitored during storage.To obtain a better understanding of the impact of processing on the progression of the reaction, three different drying techniques were studied and compared on pilot scale: freeze-drying, spray-drying and drum-drying. The extent of the reaction during prolonged storage for 200 days was studied, considering three storage variables: temperature, relative humidity (RH) and time.The kinetics of the available lysine in a commercial, industrially produced SMP was subsequently established over 30 days (the maximum recommended period for the consumption of opened packages) under conditions normally encountered during domestic storage. Furthermore, theearly and advanced stages of the reaction were studied in selected infant formulas available on the Swedish market.The results of these studies showed that the drying technique had a significant impact on the initiation of the Maillard reaction. Furthermore, the storage variables (temperature, RH and time) were also crucial factors in the gradual progression of the reaction during storage. The pattern of the decrease in the available lysine content during 200 days of storage was similar, regardless of the type of SMP. After storage at 52% RH and 30 ºC, a 39.2 – 45.9% decrease in the available lysine content was seen after 200 days. The corresponding value following storage at 52% RH and 20 ºC was 21.2 – 31.8%, indicating the importance of the storage temperature. Storage at 33% RH and 30 ºC caused a 5.2 – 22.4% decrease in the available lysine content, while no significant decrease in the available lysine content was seen after storage at 33% RH and 20 ºC, thus it was considered to be the ideal storage conditions for SMP.Studies of the advanced phase of the Maillard reaction using CML revealed that twice as much CML was formed in the spray-dried powders, than in the freeze-dried samples, after 200 days. The corresponding value in the drum-dried samples was 1.6 times that in the freeze-dried samples.The findings of this work have practical implications for SMP and SMP-based products in the food industry, and can be used to predict and control the Maillard reaction during storage, in order to ensure the safety of these products on the market.
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| 3. |
- Aaltonen, Emil
(author)
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Prokaryotic Arsenic Resistance - Studies in Bacillus subtilis
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Arsenic is a toxic metalloid which is found all over the globe. Due to its toxicity and wide abundance, all living organisms have evolved intrinsic arsenic resistance systems. In this study, three proteins that provide arsenic resistance in the Gram-positive bacterium Bacillus subtilis have been investigated. Acr3 is a trans-membrane protein that extrudes arsenite to the cell exterior. It belongs to the ACR family of arsenite transporters. Experimental data on the topology of Acr3, the first ever for a member of the ACR family, is provided and show that Acr3 has 10 trans-membrane helices. Both the N- and C-terminal ends of Acr3 are located to the cytoplasm and the protein has unusually short loops connecting its helices. ArsR is an arsenite sensitive transcription regulator that controls the expression of genes encoding arsenic resistance proteins. Experiments show that the operator site for ArsR from B. subtilis consists of a 6-6-6 inverted repeat and that DNA binding by ArsR involves formation of higher order multimers of the protein. The ArsK (former YqcK) protein has an unknown function. The present study shows that the arsK gene contributes to resistance towards both arsenite and arsenate. The results indicate that the function of ArsK is important in an aerobic environment and that it decreases the inhibitory effect that arsenite has on the sporulation efficiency of B. subtilis. A function of ArsK that involves an enzymatic addition of low molecular weight thiols to arsenic is proposed.
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| 4. |
- Aaltonen, H Laura
(author)
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Measuring distal airspace dimensions with nanoparticles. Initial development of a diagnostic method.
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Chronic obstructive pulmonary disease (COPD) consists of emphysema and bronchial disease. The pulmonary function tests currently used to diagnose COPD have poor sensitivity for early disease. This may delay diagnosis and lead to a poorer prognosis compared to establishing the diagnosis at an earlier stage.The aim of this thesis was to investigate a new nanoparticle-based method, termed Airspace Dimension Assessment (AiDA), to chart distal airspace morphology, and to examine the technique as a possible diagnostic biomarker foremphysema. In AiDA, inhaled nanoparticles’ deposition behavior is utilized to characterize distal airspace properties.Nanoparticles, as opposed to larger particles, are able to penetrate into the distal lung, where they deposit almost exclusively by diffusion. The particles’ likelihood to deposit is dependent on the diffusion distance. The thesis isbased on the hypothesis that in persons with enlarged, emphysematous airspaces, fewer particles will deposit, as opposed to healthy persons with narrower airspaces.In paper I, significant nanoparticle deposition differences between 19 COPD-patients with mainly moderate-to advanced emphysema and 19 healthy controls were found. The deposition correlated to disease severity as measured by computed tomography (CT) densitometry and diffusion capacity for carbon monoxide (DL,CO). In paper II, nanoparticle deposition was used to calculate distal airspace radius in 19 healthy volunteers. The radius correlated to lung density as measured by magnetic resonance imaging (MRI). In paper III, the average radius in 403 individuals without previous pulmonary disease or respiratory symptoms was found to be 293 ± 36 μm. The radius and its variation in population was found to be approximately comparative to other methods. It was noted that the radius was on average 13 μm larger in male ever-smokers compared to never-smokers, which may reflect early smoking-related changes. In paper IV, we concluded that in a population sample of 618 individuals, the persons with computed tomography evidence of emphysema (N = 47) had significantly larger distal airspace radii compared to persons without emphysema. We also showed that comorbidities did not significantly affect the results.In conclusion, we suggest the AiDA radius is a promising biomarker candidate for emphysema. Further validating studies, including a diagnostic study in a population seeking health care attention with symptoms and historyindicative of COPD, are warranted.
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| 5. |
- Aaltonen, Kristina
(author)
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Mating system evolution and self-incompatibility in the wild plant species Brassica cretica
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Compared to animals like ourselves, plants have a very flexible sexual life. Most plants are, for example, hermaphrodites with the potential capacity for reproduction by self-fertilization (or selfing). While selfing can provide several definite advantages for the individual plant, there is a downside; mainly the severe reduction in fitness due to inbreeding depression. To avoid the negative consequences of selfing, many hermaphrodite plant species have evolved an intricate self-recognition – or self-incompatibility (SI) – system that prevents fertilization by cognate pollen. SI is in the majority of cases genetically controlled by a narrowly delimited region of the genome, called the S locus. The S locus contains several tightly linked genes, two of which – SRK and SCR – determine the pistil (female) and pollen (male) SI recognition type. One of the best-characterized SI systems is found in the Brassicaceae family, which includes the model plant Arabidopsis thaliana and a number of economically important crop species of the Brassica genus, e.g. rape seed, cabbage, and turnip. For evolutionary biologists, SI have long been a prominent and fascinating example of Darwinian natural selection acting in a frequency-dependent manner, i.e. the rarer a genetic variant becomes, the more favoured by natural selection it is. For the S locus, this means that a very large number of variants – or haplotypes – are expected to be maintained in a population and that the DNA sequences of different haplotypes will be very divergent. However, until recently there has been a shortage of empirical studies from natural plant populations to test these, and other, theoretical predictions of S locus evolutionary dynamics. In this thesis, I have produced the largest SRK and SCR DNA sequence data set from a wild Brassica species available to date. These data have allowed me to explore, in more detail than previously possible, the population genetic properties and the evolutionary history of the Brassica S locus. Moreover, accompanying studies of the pattern of inheritance of S locus variants and the occurrence of self-fertilization in natural B. cretica population have added novel information of great value to the understanding of how plants produce offspring in nature.
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| 6. |
- Aardal Lönnerfors, Celine
(author)
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Robot-assisted laparoscopy for benign uterine disease. Feasibility, outcome and hospital cost.
- 2015
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Doctoral thesis (other academic/artistic)abstract
- The introduction of the laparoscope was a milestone within gynecologic surgery. Despite evidence of better perioperative outcome compared to laparotomy, laparoscopy is mostly performed for less advanced surgical procedures and the uptake of laparoscopic hysterectomy has been slow. An effort to preserve the clinical benefits of laparoscopic surgery and facilitate the performance of more advanced surgery has led to the development of robot-assisted laparoscopic surgery. Technical progress has been advantageous for the patient from a historical point of view, but this cannot be assumed without proper evaluation. As for all surgical approaches, it is important to recognize the possible applications of robotic surgery as well as proper patient selection both from a clinical and economical point of view. The overall aim of this thesis was to investigate the possible applications, clinical outcome and hospital cost of robot-assisted laparoscopic surgery for benign uterine disease at a single institution following the introduction of robotic surgery. Study I: Evaluating the first 1000 robotic surgeries performed showed that a surgical robot provides the possibility to offer minimally invasive surgery to a larger patient population with low rates of conversions and intraoperative complications. Study II: 31 women with symptomatic, deep intramural myomas and either otherwise unexplained infertility or myomas with a possible effect on conception had a pregnancy rate following robotic myomectomy of 68%. Study III: All women (n=114) with a BMI ≥ 30 kg/m2 who underwent a simple hysterectomy by robotics or laparotomy during the study period were included. Robot-assisted laparoscopic hysterectomy in obese women was associated with shorter hospital stay, less bleeding, and fewer complications and longer operative time compared to laparotomy although the operative times for morbidly obese women were similar between robotics and laparotomy. Study IV: 122 women planned for minimally invasive hysterectomy for benign disease were randomly allocated to either robot-assisted- or traditional, minimally invasive hysterectomy in a 1:1 proportion with vaginal hysterectomy as a primary choice in the latter. From the perspective of hospital costs, robotic-assisted hysterectomy is not advantageous for treating non-complex benign conditions when a vaginal approach is feasible in a high proportion of patients. A similar hospital cost is attainable for laparoscopy and robotics when the robot is a preexisting investment. Study V: Complication rates in 949 women planned for robotic hysterectomy for malignant (75%) and benign (25%) gynecological disease over an 8-year period with special awareness of complications possibly related to robot specific risk factors. Intraoperative- and postoperative complications and complications possibly related to the robotic approach diminish with training, experience and refinement of practice. Study VI: All women (n=483) undergoing hysterectomy for benign disease during 2013 and 2014. Vaginal hysterectomy was associated with the lowest hospital cost and robotic hysterectomy with the lowest rate of perioperative complications. Procedure-specific proficiency influences outcome. Robotic hysterectomy for benign disease is clinically advantageous and economically feasible in complex cases, when performed by high volume surgeons.
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| 7. |
- Abaravicius, Juozas
(author)
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Demand Side Activities for Electric Load Reduction
- 2007
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Doctoral thesis (other academic/artistic)abstract
- The research described in this thesis, focuses on some activities on the demand side that could reduce peak load in electricity system by using consumer flexibility i.e. by increasing the demand side response to signals coming from the energy market. The major objective is to test and analyse different strategies to reduce peak load at the demand side considering their techno-economic, environmental and behavioural aspects. Both quantitative and qualitative research methods were used, including the detailed energy use data evaluation, direct and indirect load control experiments and interviews with residential and commercial consumers and utilities. One general conclusion of this research process is that there's a lack of knowledge and information on load demand variation and its consequences both on the consumer side and the utility side. New automated interval metering technologies enable 'visibility' of electricity use, however this potentially valuable information is rarely analysed and used. Modern metering and communication systems enable utilities to perform direct load control measures and to automate demand response. As the experiments with direct load control at residential consumers show, these measures could be implemented without significant comfort losses for the consumers. However, the value of this kind of demand side actions needs to be clearly expressed or quantified both for consumers and the supplier. Indirect load control with the help of various types of pricing is possible, but needs to have more significant financial motivation for the consumers than the present offers give. The results of the analysed examples of a tariff with a load demand component indicate that consumers' electrical expenses have to be more considerably reduced if they are to significantly 'improve' the consumption patterns. Utilities, for example one of those analysed in our case studies, may not assess indirect load control as a reliable resource. Therefore the integration of direct and indirect load control measures could be an attractive solution for them. Load reduction strategies at the demand side could influence the environmental performance of an energy system by decreasing emissions and preventing the distortion of territories. Nevertheless, it should be emphasized that the environmental effects depend on the prevalent generation and transmission system and could be different on different levels - regional, national and local - as the analysis example of the Swedish case, described in this thesis, shows. Load management and demand response could be considered as a socially responsible behaviour rather than only a solution to techno-economic problems of an energy market. The results of this research showed interesting examples proving that certain residential and commercial consumers are willing to participate in demand response programs from a corporate social responsibility point of view.
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| 8. |
- Abariute, Laura
(author)
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Engineered nanomaterials in in vivo and in vitro models
- 2018
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Doctoral thesis (other academic/artistic)abstract
- Nanotechnology and engineered nanomaterials (ENM) empower existing technologies. One of the great examples are III-V semiconductor nanowires (NW), which have a broad application range. The occupational safety and hazard organizations draw attention to ENM, as their physical and chemical characteristics differ from the ones of bulk materials. Additionally, the NW high aspect ratio geometry is of great concern, since it resembles the morphology of asbestos. Moreover, due to their small size, ENM materials are hard to detect and identify using conventional methods. During ENM technology development and large-scale production, the highest risk of human exposure is via inhalation. Therefore, we need to study how NW affect lung tissue using experimental exposure models. The work in this thesis aimed at filling the knowledge gap in ENM detection and identification, as well as understanding III-V semiconductor NW effects in in vitro and in vitro models.We have used enhanced darkfield microscopy – hyperspectral imaging method to detect and identify ceria nanoparticles in three differently prepared samples, and compared different combinations of data analysis methods. The remaining part of the thesis was devoted to the study of the III-V semiconductor NW effects on cells and tissue in vitro and in vivo. We have exposed two types of cell cultures (primary human lung (SAE) and human lung adenocarcinoma cell line (A549)) to gallium phosphide (GaP) NW. We observed that both type of cells are capable to engulf NW after 2 days, and that NW do not have any effect on the SAE and A549 cell morphology after 7 and 5 days, respectively. The NW concentrations used in this work are not toxic to A549 cells, since we did not see a change in cell mobility, viability or changes in ROS levels. After inhibiting specific endocytosis pathways in A549 cells, we showed that NW are actively taken up via phagocytosis and/or macropinocytosis.Additionally, we have performed in vivo mice exposure to GaP NW via intratracheal instillation. We have observed that NW induce an inflammation and allergic reaction of similar levels as the ones observed after exposure to carcinogenic multiwall carbon nanotubes. Additionally, we show that NW are capable to cross tissue barriers and reach distant organs after 28 days, however without introducing changes to the organ tissues. Lastly, we have performed a pilot study, where we investigated the effect of NW photodiodes on A549 cells. We observed that the presence of light inhibits cell proliferation. Furthermore, we show that the chemical make-up of the photodiodes is important, since some photodiodes dissolve in water based cell culturing media and release toxic compounds.
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| 9. |
- Abbas, Taimoor
(author)
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Measurement Based Channel Characterization and Modeling for Vehicle-to-Vehicle Communications
- 2014
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Doctoral thesis (other academic/artistic)abstract
- Vehicle-to-Vehicle (V2V) communication is a challenging but fast growing technology that has potential to enhance traffic safety and efficiency. It can also provide environmental benefits in terms of reduced fuel consumption. The effectiveness and reliability of these applications highly depends on the quality of the V2V communication link, which rely upon the properties of the propagation channel. Therefore, understanding the properties of the propagation channel becomes extremely important. This thesis aims to fill some gaps of knowledge in V2V channel research by addressing four different topics. The first topic is channel characterization of some important safety critical scenarios (papers I and II). Second, is the accuracy or validation study of existing channel models for these safety critical scenarios (papers III and IV). Third, is about channel modeling (paper V) and, the fourth topic is the impact of antenna placement on vehicles and the possible diversity gains. This thesis consists of an introduction and six papers: Paper I presents a double directional analysis of vehicular channels based on channel measurement data. Using SAGE, a high-resolution algorithm for parameter estimation, we estimate channel parameters to identify underlying propagation mechanisms. It is found that, single-bounce reflections from static objects are dominating propagation mechanisms in the absence of line-of-sight (LOS). Directional spread is observed to be high, which encourages the use of diversity-based methods. Paper II presents results for V2V channel characterization based on channel measurements conducted for merging lanes on highway, and four-way street intersection scenarios. It is found that the merging lane scenario has the worst propagation condition due to lack of scatterers. Signal reception is possible only with the present LOS component given that the antenna has a good gain in the direction of LOS. Thus designing an antenna that has an omni-directional gain, or using multiple antennas that radiate towards different directions become more important for such safety critical scenarios. Paper III presents the results of an accuracy study of a deterministic ray tracing channel model for vehicle-to-vehicle (V2V) communication, that is compared against channel measurement data. It is found that the results from measurement and simulation show a good agreement especially in LOS situations where as in NLOS situations the simulations are accurate as far as existing physical phenomena of wave propagation are captured by the implemented algorithm. Paper IV presents the results of a validation study of a stochastic NLOS pathloss and fading model named VirtualSource11p for V2V communication in urban street intersections. The reference model is validated with the help of independent channel measurement data. It is found that the model is flexible and fits well to most of the measurements with a few exceptions, and we propose minor modifications to the model for increased accuracy. Paper V presents a shadow fading model targeting system simulations based on channel measurements. The model parameters are extracted from measurement data, which is separated into three categories; line-of-sight (LOS), LOS obstructed by vehicles (OLOS), and LOS blocked by buildings (NLOS), with the help of video information recorded during the measurements. It is found that vehicles obstructing the LOS induce an additional attenuation in the received signal power. The results from system level vehicular ad hoc network (VANET) simulations are also presented, showing that the LOS obstruction affects the packet reception probability and this can not be ignored. Paper VI investigates the impact of antenna placement based on channel measurements performed with four omni-directional antennas mounted on the roof, bumper, windscreen and left-side mirror of the transmitter and receiver cars. We use diversity combining methods to evaluate the performance differences for all possible single-input single-output (SIMO), multiple-input single-output (MISO) and multiple-input multiple-output (MIMO) link combinations. This investigation suggests that a pair of antennas with complementary properties, e.g., a roof mounted antenna together with a bumper antenna is a good solution for obtaining the best reception performance, in most of the propagation environments. In summary, this thesis describes the channel behavior for safety-critical scenarios by statistical means and models it so that the system performance can be assessed in a realistic manner. In addition to that the influence of different antenna arrangements has also been studied to exploit the spatial diversity and to mitigate the shadowing effects. The presented work can thus enable more efficient design of future V2V communication systems.
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| 10. |
- Abbasi, Maisam
(author)
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Exploring Themes and Challenges in Developing Sustainable Supply Chains - A Complexity Theory Perspective
- 2014
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Doctoral thesis (other academic/artistic)abstract
- To develop sustainable supply chains in a way that their negative environmental and social effects are minimized, shortand long-term targets should be set. The transformation of supply chains towards these targets calls for the development of innovative strategies and the need to continuously identify, classify, and tackle the challenges that can hinder the execution of such strategies. To develop innovative strategies, the patterns of current trends and themes need to be learned and the missing ones need to be identified. The purpose of this research was to explore themes and challenges in developing sustainable supply chain activities from theoretical and empirical perspectives. Six research studies (RS) were designed and carried out. Two explored the patterns of the themes and challenges in making supply chains environmentally and socially sustainable in general (RS1, RS2). One explored freight transport (RS3), one, urban freight distribution (RS4), and one, logistical services (RS5) in particular. RS6 explored a complexity theory perspective (CTP) on managing, governing, and developing sustainable supply chains activities. A CTP was chosen because of its applicability and ability to provide an understanding of the complex phenomena that sustainable development and supply chains represent. During and after the design of each research study, data were collected from a variety of sources and then analyzed by different researchers on some occasions and by different methods. Thus, the research design, data collection, and data analysis were mixed and overlapping, because they were not completely sequentially carried out. The aim of the analysis was to generate knowledge by (re)organizing and categorizing the data collected, by exploring the meaning of the data (i.e., generating information), and identifying their patterns of associations. After assessing the quality of the synthesized knowledge, the results were communicated to several target groups through several communication channels. In RS1, five major themes and challenges were identified in making supply chains environmentally sustainable. RS5 led to a deeper understanding of the insights of logistics service providers (LSPs) about the challenges identified in RS1. RS2 led to the identification of five major themes and eight major challenges in making supply chains socially sustainable. In the context of freight transport in RS3, fifteen major themes and five major challenges emerged. In the context of urban freight distribution in RS4, these numbers were eight major themes and seven major challenges. However, the results (i.e., the generated knowledge) about the themes and challenges were subjective: They were influenced by my interpretation of what had been said, observed, or scientifically written. The results were also relative (related to what had been said, observed, or scientifically written), and influenced by the different methods for collection and analysis of data. By combining the thirty-three identified themes in the research studies and classifying them based on their similarities and overlap, four central themes in making supply chains sustainable emerged out: sustainability in goods and services, sustainability in resources, sustainability in corporation, and sustainability in management and/or governance. Similarly, by combining the twenty-four identified challenges in the research studies and classifying them based on their similarities and overlap, five central challenges in making supply chains sustainable emerged out: shifting the values, difficulties of operationalization, dealing with complexity, difficulties of corporate governance, and SMEs difficulties. Taking a CTP was beneficial in understanding the complexity involved in the central themes of making supply chains sustainable. It also led to further propositions for tackling the challenges.
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