| 1. |
- Holmbom, Martin, 1984-
(författare)
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Clinical Impact of Bloodstream Infections – Characterization, Risk factors and Outcome
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Bloodstream infection (blood poisoning) and antibiotic resistance are increasing worldwide, and already cause the loss of millions of human lives each year. According to the World Health Organisation (WHO), bloodstream infections (BSIs) represent 20% of global mortality on a par with cardiac infarct, stroke, and major trauma. BSI may occur when bacteria from a focus of infection gain access to the circulation (bacteraemia). BSIs are usually divided into two subclasses: community- and hospital-onset infections, since disease this involves different patient groups, types of bacteria, and reasons for infection. Compared to other countries, Sweden has been fortunate in having a relatively low death rate from BSI and low antibiotic resistance. However, as our lifestyle changes, the age of the population increases with more disease as a result, and as the healthcare system responds, death from infection and antibiotic resistance are on the increase. It is important that we recognise ”warning symptoms” if we are to manage BSIs correctly and initiate effective treatment. It is difficult to design individualised empirical treatment, so it is very important to be aware of risk factors for BSI and local resistance patterns, and to have an effective management programme. Bacterial resistance to antibiotics is an increasing problem, especially in bowel organisms that can cause infections that are very difficult to treat. In short, antibiotic resistance arises as a result of evolutionary processes where bacteria protect themselves by developing resistance genes. These genes can be exchanged between similar organisms or transmitted to others that in turn cause resistant infection. The use of antibiotics leads to an evolutionary/selection process leading to resistance in bacteria, both normal and pathogenic, enabling resistant organisms to survive, thrive, and go on to cause infection. Antibiotic resistance is a threat to global health. This thesis aims to increase our awareness of a large group of patients who suffer bloodstream infection. BSIs are increasing globally, and the death toll is high. Antibiotic resistance is an increasing threat to the health of the population, and we are inundated by alarming reports of resistance getting out of control. What is the situation in Sweden, and can we identify risk factors for BSI and mortality? In Study I, our aim was to study the incidence and mortality of BSI in Östergötland. To be able to do this, a large patient population stretching over several years was required. The study design was thus population-based in the form of an observational cohort study where all blood culture results from 2000 to 2013 were analysed, and evaluated from clinical data. A total of 109,938 results were analysed resulting in 11,480 BSIs. We saw that the incidence of BSI increased by 64% (mostly community-onset BSIs). We also saw that mortality increased by 45%. These results illustrate the importance of nationwide cooperation to combat the increasing problem of BSI and its mortality, and the establishment of a nationwide BSI register. The aim of Study II was to assess resistance development in Östergötland and its relationship to mortality. A total of 9,587 microorganisms were analysed between 2008 and 2016. We observed an increase in quinolone resistance (3.7-7.7%) and cephalosporin resistance (2.5-5.2%) amongst Enterobacteriaceae. We then looked at BSIs caused by multiresistant bacteria showing a total of 245 cases (2.6%); an increase of 300%. Despite this, we did not see an increased mortality in this group. There are several possible explanations for the increase in BSI mortality of which antibiotic resistance is a predominant factor globally. We were unable to show this in our study, even so mortality is increasing and is currently at a high level. In Study III we therefore analysed risk factors associated with death during a community-acquired BSI, focusing on preliminary prehospital and hospital management. In a retrospective case-control study on 195 deaths matched 1:1 regarding age, gender, and microorganism, with 195 survivors (controls). Results showed that many patients had contacted the primary healthcare system because of infection before they became severely ill, and that the strongest affectable risk factor for death was delay (>24h) between primary healthcare visit and admission to hospital. This shows the need for increased awareness in society and amongst the medical profession of those patients at risk and symptoms that should raise the alarm, leading to more rapid treatment. In Studies I and II we found an increase in both BSIs and mortality, we also saw an increase in antibiotic resistance and multiresistant bacteria, mainly ESBL-producing E. coli. On the other hand, we did not see any coupling between multiresistance and mortality in this Swedish population. E. coli is a gram-negative bacteria that causes most BSIs. Since E. coli is predominantly a urine tract pathogen, Study IV aimed to study BSIs caused by ESBL-producing E. coli originating from the urinary tract. We studied the prevalence of E. coli clones, resistance genes and risk factors, as well as any signs of increased mortality from ESBL-producing E. coli compared to sensitive E. coli. Our main finding was a surprisingly low mortality from ESBL-producing E. coli (3%). Most patients in the ESBL-producing E. coli group received inadequate antibiotic treatment for at least 48h, but we did not see any sign of increased mortality or risk for serious sepsis with circulatory failure in this group. This finding is interesting and opens up for new studies on virulence factors and immunological factors that govern the immune response to BSI. The implementation of cost-effective monitoring systems including clinical microbiological epidemiology and early identification of BSI, together with information campaigns aimed at the public as well as healthcare personnel regarding patients at risk and symptoms giving cause for alarm, should lead to a radical reduction in morbidity and mortality from BSI. This requires new diagnostic tools to individualise both antibiotic treatment and targeted management based on microorganism virulence factors. Modernisation of the medical journal system with algorithms aimed at early identification of risk patients and automated suggestions for empirical antibiotic treatment based on antibiotic resistance seen in previous cultures and local resistance patterns, would certainly improve management. Furthermore, new immunological tests showing the type of immunological reaction to a serious BSI will lead to individualised immunotherapy that, together with antibiotic treatment, will further improve patient care in this important group.
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| 2. |
- Andéhn, Mikael, 1982-
(författare)
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Place-of-Origin Effects on Brand Equity : Explicating the evaluative pertinence of product categories and association strength
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The country-of-origin effect - the alteration of judgment derived from an association to a place, is a much studied phenomenon with great potential implications for brand management and international marketing. However, in light of criticism towards the lack of conceptual development the extant literature, the relevance of the effect has been brought into question.Through an exploration of the psychology of the association between brands and places, the country-of-origin effect is reimagined focusing on the role of association strength as well as how the interplay between place and product categories can shape consumer attitudes.The results of a series of psychometric tests suggest that association strength and the interplay between place and product category constitute antecedent conditions that are crucial for determining if a country-of-origin effect will occur. These findings, and their implications for future research as well as for practice, suggest that a reevaluation of the country-of-origin effect with a widening of the scope to encompass the commercial relevance of place writ large is warranted.
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| 3. |
- Sundling, Catherine, 1962-
(författare)
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Overall Accessibility of Public Transport for Older Adults
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is based on four studies that explore accessibility for older adults during whole trips by public transport. The overall goal was to gain knowledge of the interrelationships among key variables and to develop a conceptual model of the overall accessibility of public transport. More specifically, the research goals were: (a) to explore links among the key variables postulated to be involved in overall accessibility and to explore the links between these variables and railway accessibility; (b) to gain a deeper understanding of links between critical incidents in traveling and travel behavior decisions; and (c) to develop a conceptual model of overall accessibility. The key variables contributing to overall accessibility are functional ability (depending partly on the person’s functional limitation or disease), travel behavior, and barriers encountered during whole-trip traveling involving train. Respondents with more than one functional limitation or disease reported lower functional ability than did those with only one such limitation and respondents with low functional ability were less frequent travelers than were those with high functional ability. Frequent travelers reported railway accessibility to be better than did those who traveled less frequently. The main barriers were ticket cost and poor punctuality, but respondents with the lowest functional ability attributed the barriers encountered to their own health. The critical incidents most frequently reported were found in the categories “physical environment onboard vehicles” and “physical environment at stations or stops”, as well as in the “pricing and planning during ticketing” phase of the trip. Five themes of reactions to critical incidents were identified that had resulted in behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. A conceptual model of overall accessibility was developed, grounded in the empirical research results. This model is summarized in the following propositions: Overall accessibility is a reciprocal relationship among the barriers/facilitators encountered, functional ability, and travel behavior. Accessibility emerges in the person–environment interaction. To understand accessibility, past experiences and future expectations should both be considered, because both will guide travel decisions.
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| 4. |
- Szychowska, Malina, 1991-
(författare)
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Effects of visual load on auditory processing
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In daily life, people need to be able to focus on a task while ignoring any task-irrelevant background noise. For example, people who work in an open-space office may have to work on a report while ignoring the background talk among co-workers. Theories of attention argue that processing of task-irrelevant auditory information should become attenuated when attentional capacity is exhausted by task-relevant stimuli, for example a visual task. According to early-filter theory, top-down attenuation of auditory responses is possible at various stages of the auditory pathway through multiple recurrent loops. Furthermore, the adaptive filtering model of selective attention suggests that filtering occurs early when concurrent visual tasks are demanding (e.g., high load) and late when tasks are easy (e.g., low load).The main aim of this thesis was to investigate whether auditory processing is attenuated during concurrent visual load manipulation, and if so, at which stage of the auditory pathway. Recurrent loops that are present throughout the entire auditory pathway should allow top-down modulation of even earliest responses, especially when accompanied by a highly demanding task. Recording these auditory responses during concurrent visual tasks with different levels of load could potentially show at which stages of auditory processing the filtering happens when the task demands are high or low, or there is no task at all.This thesis tested the effects of visual load manipulation on the responses originating from different stages of the auditory pathway: mismatch negativity (MMN) to duration in Study I, MMN to frequency in Study III, auditory steady-state responses (ASSRs) to a 40-Hz modulation frequency in Study IV, and ASSRs to 20-, 40-, and 80-Hz modulation frequencies in Study V. Additionally, Study II compared different control conditions (cascade vs. no-repetition control) for evoking MMN to find a design that reduces confounds in the MMN. Results of Study II showed that cascade and no-repetition control are comparable control conditions for evoking MMN.For the effects of visual load manipulation on auditory MMN (low vs. high load), results showed moderate evidence for the effect of load on duration MMN and moderate evidence for no effect of load on frequency MMN. However, results for the duration MMN might be confounded by physical differences between the low load and high load conditions in the visual task, and by a biased oddball paradigm used to evoke the MMN. Thus, it is most likely that auditory MMN is not affected by visual load (low vs. high).For the effects of visual load on ASSRs (no, low, and high load), results showed moderate to strong evidence for no effects of load manipulation on ASSRs, but some comparisons were inconclusive. The convincing evidence obtained in Studies IV and V points to the robustness of ASSRs against visual load manipulation.Because it is most likely that neither MMN nor ASSRs are affected by visual load manipulation, results presented in this thesis support the idea that attentional resources are modality specific. Because it is possible that filtering occurs at one stage of auditory processing and does not change with the concurrent task demands, the present results do not rule out the early-filter theory. However, results are inconsistent with the adaptive filtering model because filtering of task-irrelevant responses does not vary with the demands of the concurrent task.
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| 5. |
- Alvarsson, Jesper J.
(författare)
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Perspectives on wanted and unwanted sounds in outdoor environments : Studies of masking, stress recovery, and speech intelligibility
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An acoustic environment contains sounds from various sound sources, some generally perceived as wanted, others as unwanted. This thesis examines the effects of wanted and unwanted sounds in acoustic environments, with regard to masking, stress recovery, and speech intelligibility.In urban settings, masking of unwanted sounds by sounds from water structures has been suggested as a way to improve the acoustic environment. However, Study I showed that the unwanted (road traffic) sound was better at masking the wanted (water) sound than vice versa, thus indicating that masking of unwanted sounds with sounds from water structures may prove difficult. Also, predictions by a partial loudness model of the auditory periphery overestimated the effect of masking, indicating that centrally located informational masking processes contribute to the effect. Some environments have also been shown to impair stress recovery; however studies using only auditory stimuli is lacking. Study II showed that a wanted (nature) sound improve stress recovery compared to unwanted (road traffic, ambient) sounds. This suggests that the acoustic environment influences stress recovery and that wanted sounds may facilitate stress recovery compared to unwanted sounds. An additional effect of unwanted sounds is impeded speech communication, commonly measured with speech intelligibility models. Study III showed that speech intelligibility starts to be negatively affected when the unwanted (aircraft sound) masker have equal or higher sound pressure level as the speech sound. Three models of speech intelligibility (speech intelligibility index, partial loudness and signal–to–noise ratio) predicted this effect well, with a slight disadvantage for the signal–to–noise ratio model. Together, Study I and III suggests that the partial loudness model is useful for determining effects of wanted and unwanted sounds in outdoor acoustic environments where variations in sound pressure level are large. But, in environments with large variations in other sound characteristics, models containing predictions of central processes would likely produce better results.The thesis concludes that wanted and unwanted characteristics of sounds in acoustic environments affect masking, stress recovery, and speech intelligibility, and that auditory perception models can predict these effects.
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| 6. |
- Axelsson, Östen, 1971-
(författare)
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Aesthetic Appreciation Explicated
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present doctoral thesis outlines a new model in psychological aesthetics, named the Information-Load Model. This model asserts that aesthetic appreciation is grounded in the relationship between the amount of information of stimuli and people’s capacity to process this information. This relationship results in information load, which in turn creates emotional responses to stimuli. Aesthetic appreciation corresponds to an optimal degree of information load. Initially, the optimal degree is relatively low. As an individual learns to master information in a domain (e.g., photography), the degree of information load, which corresponds to aesthetic appreciation, increases. The present doctoral thesis is based on three empirical papers that explored what factors determine aesthetic appreciation of photographs and soundscapes. Experiment 1 of Paper I involved 34 psychology undergraduates and 564 photographs of various motifs. It resulted in a set of 189 adjectives related to the degree of aesthetic appreciation of photographs. The subsequent experiments employed attribute scales that were derived from this set of adjectives. In Experiment 2 of Paper I, 100 university students scaled 50 photographs on 141 attribute scales. Similarly, in Paper II, 100 university students scaled 50 soundscapes on 116 attribute scales. In Paper III, 10 psychology undergraduates and 5 photo professionals scaled 32 photographs on 27 attribute scales. To explore the underlying structure of the data sets, they were subjected to Multidimensional Scaling and Principal Components Analyses. Four general components, related to aesthetic appreciation, were found: Familiarity, Hedonic Tone, Expressiveness, and Uncertainty. These components result from the higher-order latent factor Information Load that underlies aesthetic appreciation.
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| 7. |
- Cornell Kärnekull, Stina, 1985-
(författare)
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Auditory and Olfactory Abilities in Blind and Sighted Individuals : More Similarities than Differences
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Blind individuals face various challenges in everyday life because of the lack of visual input. However, since they need to rely on the non-visual senses for everyday tasks, for instance, when navigating the environment, the question has been raised as to whether perceptual and cognitive abilities in these senses may be enhanced. This question has mainly been addressed for auditory and tactile abilities, whereas there is considerably less research into the chemical senses, such as olfaction. However, to determine whether blindness has general effects, different senses and types of tasks should be studied, preferably in one and the same study. Therefore, throughout this thesis, analogous auditory and olfactory tasks that varied in cognitive complexity were studied. In Study I, absolute thresholds, discrimination, identification, episodic recognition (i.e., after a short retention interval), metacognition, and self-reported imagery ability were assessed in early blind, late blind, and sighted participants. The only objective measure on which the blind and sighted clearly differed was the auditory episodic recognition task. The fact that early blind but not late blind participants displayed better memory than the sighted suggested that the onset age of blindness may be important for whether this ability becomes enhanced following blindness. Furthermore, the early blind participants rated their auditory imagery ability higher than the sighted, whereas both early and late blind participants rated their olfactory imagery ability higher than the sighted. In Study II, the participants from Study I were followed up after more than a year and retested on auditory and olfactory episodic recognition and identification. This time, the early blind displayed no advantage over the sighted, suggesting that the influence of blindness on auditory memory may be modulated by the length of the retention interval. Moreover, in line with Study I, identification of sounds and odors was similar in the three groups. In Study III, early blind and sighted participants were examined for potential differences in autobiographical memory as evoked by sounds and odors, respectively. Blindness did not influence the reminiscence bumps (i.e., memory peaks in certain age intervals) or have any clear impact on the number of retrieved sound- or odor-evoked memories. Taken together, the present findings indicate that blindness has no general influence across tasks or sensory modalities. Rather, specific auditory abilities, such as episodic memory, may be enhanced in blind individuals, although such effects may depend on both the onset age of blindness and the length of the retention interval. In conclusion, for most perceptual and cognitive abilities examined, performance seemed unaffected by blindness.
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| 8. |
- Rådsten Ekman, Maria
(författare)
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Unwanted wanted sounds : Perception of sounds from water structures in urban soundscapes
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Water structures, for example, fountains, are common design elements in urban open public spaces. Their popularity is probably explained by their visual attractiveness. Less is known about how the sounds of water struc-tures influence the urban soundscape. This thesis explores the potential ef-fects of water sounds on urban soundscapes based on the character of water sounds. Three psychoacoustic studies were conducted in which listeners rated the perceptual properties of various water sounds. Study I found that water sounds had a limited ability to mask traffic noise, as the frequency composition of the sounds resulted in road-traffic noise masking fountain sounds more than the reverse. A partial loudness model of peripheral audito-ry processes overestimated the observed masking effect of water sound on road-traffic noise, and it was suggested that this was related to central pro-cesses, in particular, target/masker confusion. In Study II, water sounds of different degrees of perceived pleasantness were mixed with road-traffic noise to explore the overall effect on soundscape quality. The overall pleas-antness was increased substantially by adding a highly pleasant water sound; however, less pleasant water sounds had no effect or even reduced overall pleasantness. This result suggests that the perceptual properties of water-generated sounds should be taken into consideration in soundscape design. In Study III, this was explored by analyzing a large set of recordings of sounds of water fountains in urban open spaces. A multidimensional scaling analysis of similarity sortings of sounds revealed distinct groups of percep-tually different fountain sounds. The group of pleasant fountain sounds was characterized by relatively low loudness and high fluctuation strength and tonality, generating purling and rippling sounds. The group of unpleasant fountain sounds was characterized by high loudness and low fluctuation strength and tonality, generating a steady-state like noisy sound.. A joint result of all three studies is that sounds from water structures with a high flow rate (i.e., a large jet and basin in Study I, a waterfall in Study II, and large fountains in Study III) generating a steady-state noisy sound should be avoided in soundscape design. Instead, soundscape design might better focus on more fluctuating water sounds, which were considered more pleasant in both studies II and III. A general conclusion from this thesis is that water-generated sounds may be used to improve the soundscape, but that great care must be taken in selecting the type of water sound to use.
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| 9. |
- Ekdahl, Christer, 1962-
(författare)
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Infective Endocarditis : aspects of pathophysiology, epidemiology, management and prognosis
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Infective endocarditis (IE) is a rare but complex disease that is fatal if untreated. With a modern combination of antimicrobial therapy and heart valve surgery, mortality is still 10-20 %. The structure of the endocarditis vegetation impedes the penetration of phagocytic cells such as monocytes and granulocytes. This leads to high bacterial counts inside the vegetation and the need for long treatment courses with a combination of intravenously administered bactericidal antibiotics.The aim of this thesis was to study the changes in epidemiology, management, and mortality at our hospital between 1980 and 2001, and to identify prognostic factors associated with mortality. To assess the issue of referral bias, differences between referred episodes and episodes from our local community were studied. Additional aims were to study the occurrence of the pro-chemotactic cytokines IL-8 and TNF-α in heart valves and vegetations during the active phase of IE, and to study the effect of the glycopeptide antibiotic vancomycin in dense staphylococcal cultures in vitro. As it is a rare and complex disease, management of IE is usually complicated for non-specialists. For this reason a computerised decision support system for IE was developed and evaluated.Between 1980 and 2001, the occurrence of Staphylococcus aureus IE and the use of early heart valve surgery increased significantly, regardless of whether the episodes were referred or of local origin. Glycopeptide antibiotics, mainly vancomycin, were used more frequently, especially among referred patients. Referred patients were younger, predominantly male, had more complications, and received surgical treatment more often than patients from our local community. The reason for the lower frequency of female patients in the referral cohort cannot be explained by more comorbidity or fewer complications. The differences between referred and local episodes seen in our study highlight the need for assessment and adjustment for referral bias in IE studies (Paper I).In six patients who needed early heart valve surgery, the largest numbers of IL-8-containing cells, and the greatest amount of inflammation, were seen in patients with short preoperative antimicrobial treatment courses. No such relationships were seen with respect to TNF-α-containing cells. The IL-8-containing cells and the inflammatory cells were predominantly scattered in the heart valve stroma or in the margin of the vegetation (Paper II). The primary effect of IL-8 is to stimulate chemotaxis of polymorphonuclear neutrophil granulocytes. This indicates that there is no deficiency of IL-8 in the area close to the vegetation as a cause of the localised agranulocytosis often present inside the vegetation.Our study revealed a need for computerised decision support systems (DSSs) in the field of IE, but to be used in clinical practice these DSSs need be part of knowledge bases covering larger domains (Paper IV). Some of our initial ideas described in Paper III, especially the use of Internet technology and the combination of rule-based advice and explanatory hypertext, will probably be included in these knowledge bases.In vitro, there is a rapid reduction of free vancomycin in broth containing dense staphylococcal cultures. Consequently, there is a simultaneous increase in broth MICs, particularly in high inocula, which is not caused by a development of resistance (Paper V). These findings need further evaluation in vivo, but indicate that the dosing regimen of vancomycin is of particular importance in staphylococcal infections with dense inocula, e.g. infective endocarditis.Diabetes mellitus and moderate to severe heart failure were independent risk factors for 6-month mortality in left-sided, Duke definite IE episodes, regardless of referral or local origin of the episodes. Early heart valve surgery had a positive impact on the 6-month mortality in the referral cohort of episodes, which may be due to referral bias (Paper VI).
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| 10. |
- Rattiste, Kalev, 1955-
(författare)
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Life History of the Common Gull (Larus canus) : A Long-Term Individual-Based Study
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- An individual’s life history is a sequence of events which eventually determine its contribution to the next generation, or fitness. These events are affected by environmental factors, genetic make-up and decisions made by an individual and its breeding partner. Recognition of these determinants helps to understand both short-term ecological changes and long-term evolutionary dynamics in a population. In this thesis long-term individual-based data on common gull (Larus canus) is used to study age-dependent reproductive success, survival, pair retention and breeding time. Collected pedigree data enabled to study genetic variation of traits and the selection on them. The reproductive success of common gulls increased steadily until very old age. This increase cannot be explained by selection effects, since individuals with lower breeding success were shown not to have lower survival. Consequently, this gain must be ascribed primarily to an age-related improvements of individual competence and/or increased reproductive effort. Annual survival of adult birds was age- and year-dependent. The latter was partly explained by winter severity. The size of the white spots on five outermost primaries predicted the bird’s future survival and divorce probabilities and hence, pair endurance capability. Gulls with larger spots enjoyed higher survival and lower divorce rates compared to birds with smaller spots. This suggests that the wing tip pattern might function as a condition dependent signal, revealing individual variation in quality. One of the advantages of persistent pair bond was the ability to start breeding early in the season. The timing of breeding of firm pairs advanced with time not only due to mates’ increasing age, but also owing to their experience together. Although both sexes had phenotypic effects on laying date, it was heritable only in females. On the phenotypic and genotypic level, early laying was under positive fecundity and survival selection in females.
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