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Papers by L. Hedman
Surgical Endoscopy, 2004
Background: We earlier showed that training in the Procedicus KSA Simulator improves the performa... more Background: We earlier showed that training in the Procedicus KSA Simulator improves the performance of tasks done later in the same simulator. However, it is still unclear how performance in a specific visual-spatial simulator context may change after training in other simulators with different visual-spatial components. In particular, the aim of this study was to test whether performance in the Procedicus Virtual Arthroscopy (VA) Knee Simulator would remain unchanged after a training session in three other simulators with different visual-spatial components. Methods: Twenty-eight medical students participated in a quasi-transfer study. They were randomly allocated to an experimental group (n = 14) and a control group (n = 14). Results: Performance in the Procedicus VA Knee Simulator did not improve after training in other simulators with different visual-spatial components (t-test p = NS). No significant correlation was found between the Procedicus VA Knee and the Minimally Invasive Surgical Trainer (MIST) simulators. Conclusion: One hour of training in different visualspatial contexts was not enough to improve the performance in virtual arthroscopy tasks. It cannot be excluded, however, that experienced trainees could improve their performance, because perceived similarity between different situations is influenced by many psychological factors, such as the knowledge or expertise of the person performing the transfer task.
Journal of Infectious Diseases, 2011
Recently, 3 new members of the genus Bocavirus, human bocavirus 2 (HBoV2), human bocavirus 3 (HBo... more Recently, 3 new members of the genus Bocavirus, human bocavirus 2 (HBoV2), human bocavirus 3 (HBoV3), and human bocavirus 4 (HBoV4), were discovered. HBoV2-4 occur mainly in the gastrointestinal tract but rarely in the respiratory tract, contrary to human bocavirus 1 (HBoV1). To investigate HBoV1-4 seroepidemiology among 195 adults and 252 wheezing children, we conducted immunoglobulin G (IgG) and immunoglobulin M (IgM) enzyme immunoassays with recombinant viruslike particles (VLPs). The children's sera were also tested for HBoV1-4 DNA by quantitative polymerase chain reaction (qPCR). Both rabbit and human antibodies to HBoV1-4 VP2 VLPs were found to be cross-reactive. After depletion of HBoV1-reactive antibodies, the HBoV2-4 approximate seroprevalences in adults were 34%, 15%, and 2% and in children aged 1-2 years 25%, 10%, and 5%, respectively. After depletion of HBoV2-4-reactive antibodies, the HBoV1 seroprevalence among adults decreased from 96% to 59%. No cross-reactivity of human anti-HBoV IgG was observed with bovine parvovirus1, parvovirus B19 or PARV4. No child was HBoV2-4 viremic. HBoV2-4 infect humans less commonly and elicit weaker B-cell responses than HBoV1. In our study HBoV2-4 did not seem to have a major etiological role in wheezing. Cross-reactivity with HBoV2-4 IgG partially accounts for the high HBoV1 seroprevalences previously reported. Correction for cross-reactivity is a prerequisite for VLP-based HBoV seroepidemiology.
Journal of Economic Geography, 2013
ABSTRACT Studies of neighbourhood effects typically investigate the instantaneous effect of point... more ABSTRACT Studies of neighbourhood effects typically investigate the instantaneous effect of point-in-time measures of neighbourhood poverty on individual outcomes. It has been suggested that it is not solely the current neighbourhood, but also the neighbourhood history of an individual that is important in determining an individual's outcomes. The effect of long-term exposure to poverty neighbourhoods on adults has largely been ignored in the empirical literature, partly due to a lack of suitable data. Using a population of parental home-leavers in Stockholm, Sweden, this study is innovative in investigating the effects of two temporal dimensions of exposure to neighbourhood environments on personal income later in life: the parental neighbourhood at the time of leaving the home and the cumulative exposure to poverty neighbourhoods in the subsequent 17 years. Using unique longitudinal Swedish register data and bespoke individual neighbourhoods, we are the first to employ a hybrid model, which combines both random and fixed effects approaches, in a study of neighbourhood effects. We find independent and non-trivial effects on income of the parental neighbourhood and cumulative exposure to poverty concentration neighbourhoods. The intergenerational transmission and exposure effects suggest the need for a more dynamic formulation of the neighbourhood effects hypothesis which explicitly takes temporal dimensions into account.
International Journal of Human-Computer Studies, 2010
More and more people entering the stage of retirement at around age 55-65 are healthy, active, an... more More and more people entering the stage of retirement at around age 55-65 are healthy, active, and also very computer-literate. This trend is rapidly changing the common image of late-midlife technology users, which rests on the assumption that they find it difficult to embrace new technologies and also that their main interests are health-related. Although technology use and lifestyles are changing, however, many other aspects of life remain the same. One of these aspects is that of the transitions, or life changes, that generally take place in these years. Besides retirement, these transitions include changes in health, housing, social interaction, work life, and personal finance. People develop different ways of coping with these transitions, which brings up interesting issues related to the late midlife stage. This paper presents a diary-aided interview study of late middle-age adults (N=24) in Finland and Sweden with a focus on the interplay between technologies and transitions. Transitions were found to play a part in how the life interests of late middle-aged persons are often conflictive, forcing them to choose from among various 'possible selves'. At its best, technology can help alleviate these tensions. This finding is exemplified in the paper's discussion of two design implications associated with particular clashes of interests, related to how daily activities are organized and how contact is maintained with one's friends and family.
Environment and Planning A, 2011
Although we know a lot about why households choose certain dwellings, we know relatively little a... more Although we know a lot about why households choose certain dwellings, we know relatively little about the mechanisms behind neighbourhood choice. Most studies of neighbourhood choice only focus on one or two dimensions of neighbourhoods: typically poverty and ethnicity. This paper argues that neighbourhoods have multiple dimensions and that models of neighbourhood choice should take these dimensions into account. We propose the use of a conditional logit model. From this approach we can gain insight into the interaction between individual and neighbourhood characteristics which lead to the choice of a particular neighbourhood over alternative destinations. We use Swedish register data to model neighbourhood choice for all households which moved to a neighbourhood in the city of Uppsala between 1997 and 2006. Our results show that neighbourhood sorting is a highly structured process where households are very likely to choose neighbourhoods where the neighbourhood population matches their own characteristics. JEL Classification:
Transactions of the Institute of British Geographers, 2013
IZA Working Papers by L. Hedman
Although we know a lot about why households choose certain dwellings, we know relatively little a... more Although we know a lot about why households choose certain dwellings, we know relatively little about the mechanisms behind neighbourhood choice. Most studies of neighbourhood choice only focus on one or two dimensions of neighbourhoods: typically poverty and ethnicity. This paper argues that neighbourhoods have multiple dimensions and that models of neighbourhood choice should take these dimensions into account. We propose the use of a conditional logit model. From this approach we can gain insight into the interaction between individual and neighbourhood characteristics which lead to the choice of a particular neighbourhood over alternative destinations. We use Swedish register data to model neighbourhood choice for all households which moved to a neighbourhood in the city of Uppsala between 1997 and 2006. Our results show that neighbourhood sorting is a highly structured process where households are very likely to choose neighbourhoods where the neighbourhood population matches their own characteristics. JEL Classification:
Studies of neighbourhood effects typically investigate the instantaneous effect of point-in-time ... more Studies of neighbourhood effects typically investigate the instantaneous effect of point-in-time measures of neighbourhood poverty on individual outcomes. It has been suggested that it is not solely the current neighbourhood, but also the neighbourhood history of an individual that is important in determining an individual's outcomes. The effect of long-term exposure to poverty neighbourhoods on adults has largely been ignored in the empirical literature, partly due to a lack of suitable data. Using a population of parental home-leavers in Stockholm, Sweden, this study is innovative in investigating the effects of two temporal dimensions of exposure to neighbourhood environments on personal income later in life: the parental neighbourhood at the time of leaving the home and the cumulative exposure to poverty neighbourhoods in the subsequent 17 years. Using unique longitudinal Swedish register data and bespoke individual neighbourhoods, we are the first to employ a hybrid model, which combines both random and fixed effects approaches, in a study of neighbourhood effects. We find independent and non-trivial effects on income of the parental neighbourhood and cumulative exposure to poverty concentration neighbourhoods. The intergenerational transmission and exposure effects suggest the need for a more dynamic formulation of the neighbourhood effects hypothesis which explicitly takes temporal dimensions into account.
Surgical Endoscopy, 2004
Background: We earlier showed that training in the Procedicus KSA Simulator improves the performa... more Background: We earlier showed that training in the Procedicus KSA Simulator improves the performance of tasks done later in the same simulator. However, it is still unclear how performance in a specific visual-spatial simulator context may change after training in other simulators with different visual-spatial components. In particular, the aim of this study was to test whether performance in the Procedicus Virtual Arthroscopy (VA) Knee Simulator would remain unchanged after a training session in three other simulators with different visual-spatial components. Methods: Twenty-eight medical students participated in a quasi-transfer study. They were randomly allocated to an experimental group (n = 14) and a control group (n = 14). Results: Performance in the Procedicus VA Knee Simulator did not improve after training in other simulators with different visual-spatial components (t-test p = NS). No significant correlation was found between the Procedicus VA Knee and the Minimally Invasive Surgical Trainer (MIST) simulators. Conclusion: One hour of training in different visualspatial contexts was not enough to improve the performance in virtual arthroscopy tasks. It cannot be excluded, however, that experienced trainees could improve their performance, because perceived similarity between different situations is influenced by many psychological factors, such as the knowledge or expertise of the person performing the transfer task.
Journal of Infectious Diseases, 2011
Recently, 3 new members of the genus Bocavirus, human bocavirus 2 (HBoV2), human bocavirus 3 (HBo... more Recently, 3 new members of the genus Bocavirus, human bocavirus 2 (HBoV2), human bocavirus 3 (HBoV3), and human bocavirus 4 (HBoV4), were discovered. HBoV2-4 occur mainly in the gastrointestinal tract but rarely in the respiratory tract, contrary to human bocavirus 1 (HBoV1). To investigate HBoV1-4 seroepidemiology among 195 adults and 252 wheezing children, we conducted immunoglobulin G (IgG) and immunoglobulin M (IgM) enzyme immunoassays with recombinant viruslike particles (VLPs). The children's sera were also tested for HBoV1-4 DNA by quantitative polymerase chain reaction (qPCR). Both rabbit and human antibodies to HBoV1-4 VP2 VLPs were found to be cross-reactive. After depletion of HBoV1-reactive antibodies, the HBoV2-4 approximate seroprevalences in adults were 34%, 15%, and 2% and in children aged 1-2 years 25%, 10%, and 5%, respectively. After depletion of HBoV2-4-reactive antibodies, the HBoV1 seroprevalence among adults decreased from 96% to 59%. No cross-reactivity of human anti-HBoV IgG was observed with bovine parvovirus1, parvovirus B19 or PARV4. No child was HBoV2-4 viremic. HBoV2-4 infect humans less commonly and elicit weaker B-cell responses than HBoV1. In our study HBoV2-4 did not seem to have a major etiological role in wheezing. Cross-reactivity with HBoV2-4 IgG partially accounts for the high HBoV1 seroprevalences previously reported. Correction for cross-reactivity is a prerequisite for VLP-based HBoV seroepidemiology.
Journal of Economic Geography, 2013
ABSTRACT Studies of neighbourhood effects typically investigate the instantaneous effect of point... more ABSTRACT Studies of neighbourhood effects typically investigate the instantaneous effect of point-in-time measures of neighbourhood poverty on individual outcomes. It has been suggested that it is not solely the current neighbourhood, but also the neighbourhood history of an individual that is important in determining an individual's outcomes. The effect of long-term exposure to poverty neighbourhoods on adults has largely been ignored in the empirical literature, partly due to a lack of suitable data. Using a population of parental home-leavers in Stockholm, Sweden, this study is innovative in investigating the effects of two temporal dimensions of exposure to neighbourhood environments on personal income later in life: the parental neighbourhood at the time of leaving the home and the cumulative exposure to poverty neighbourhoods in the subsequent 17 years. Using unique longitudinal Swedish register data and bespoke individual neighbourhoods, we are the first to employ a hybrid model, which combines both random and fixed effects approaches, in a study of neighbourhood effects. We find independent and non-trivial effects on income of the parental neighbourhood and cumulative exposure to poverty concentration neighbourhoods. The intergenerational transmission and exposure effects suggest the need for a more dynamic formulation of the neighbourhood effects hypothesis which explicitly takes temporal dimensions into account.
International Journal of Human-Computer Studies, 2010
More and more people entering the stage of retirement at around age 55-65 are healthy, active, an... more More and more people entering the stage of retirement at around age 55-65 are healthy, active, and also very computer-literate. This trend is rapidly changing the common image of late-midlife technology users, which rests on the assumption that they find it difficult to embrace new technologies and also that their main interests are health-related. Although technology use and lifestyles are changing, however, many other aspects of life remain the same. One of these aspects is that of the transitions, or life changes, that generally take place in these years. Besides retirement, these transitions include changes in health, housing, social interaction, work life, and personal finance. People develop different ways of coping with these transitions, which brings up interesting issues related to the late midlife stage. This paper presents a diary-aided interview study of late middle-age adults (N=24) in Finland and Sweden with a focus on the interplay between technologies and transitions. Transitions were found to play a part in how the life interests of late middle-aged persons are often conflictive, forcing them to choose from among various 'possible selves'. At its best, technology can help alleviate these tensions. This finding is exemplified in the paper's discussion of two design implications associated with particular clashes of interests, related to how daily activities are organized and how contact is maintained with one's friends and family.
Environment and Planning A, 2011
Although we know a lot about why households choose certain dwellings, we know relatively little a... more Although we know a lot about why households choose certain dwellings, we know relatively little about the mechanisms behind neighbourhood choice. Most studies of neighbourhood choice only focus on one or two dimensions of neighbourhoods: typically poverty and ethnicity. This paper argues that neighbourhoods have multiple dimensions and that models of neighbourhood choice should take these dimensions into account. We propose the use of a conditional logit model. From this approach we can gain insight into the interaction between individual and neighbourhood characteristics which lead to the choice of a particular neighbourhood over alternative destinations. We use Swedish register data to model neighbourhood choice for all households which moved to a neighbourhood in the city of Uppsala between 1997 and 2006. Our results show that neighbourhood sorting is a highly structured process where households are very likely to choose neighbourhoods where the neighbourhood population matches their own characteristics. JEL Classification:
Transactions of the Institute of British Geographers, 2013
Although we know a lot about why households choose certain dwellings, we know relatively little a... more Although we know a lot about why households choose certain dwellings, we know relatively little about the mechanisms behind neighbourhood choice. Most studies of neighbourhood choice only focus on one or two dimensions of neighbourhoods: typically poverty and ethnicity. This paper argues that neighbourhoods have multiple dimensions and that models of neighbourhood choice should take these dimensions into account. We propose the use of a conditional logit model. From this approach we can gain insight into the interaction between individual and neighbourhood characteristics which lead to the choice of a particular neighbourhood over alternative destinations. We use Swedish register data to model neighbourhood choice for all households which moved to a neighbourhood in the city of Uppsala between 1997 and 2006. Our results show that neighbourhood sorting is a highly structured process where households are very likely to choose neighbourhoods where the neighbourhood population matches their own characteristics. JEL Classification:
Studies of neighbourhood effects typically investigate the instantaneous effect of point-in-time ... more Studies of neighbourhood effects typically investigate the instantaneous effect of point-in-time measures of neighbourhood poverty on individual outcomes. It has been suggested that it is not solely the current neighbourhood, but also the neighbourhood history of an individual that is important in determining an individual's outcomes. The effect of long-term exposure to poverty neighbourhoods on adults has largely been ignored in the empirical literature, partly due to a lack of suitable data. Using a population of parental home-leavers in Stockholm, Sweden, this study is innovative in investigating the effects of two temporal dimensions of exposure to neighbourhood environments on personal income later in life: the parental neighbourhood at the time of leaving the home and the cumulative exposure to poverty neighbourhoods in the subsequent 17 years. Using unique longitudinal Swedish register data and bespoke individual neighbourhoods, we are the first to employ a hybrid model, which combines both random and fixed effects approaches, in a study of neighbourhood effects. We find independent and non-trivial effects on income of the parental neighbourhood and cumulative exposure to poverty concentration neighbourhoods. The intergenerational transmission and exposure effects suggest the need for a more dynamic formulation of the neighbourhood effects hypothesis which explicitly takes temporal dimensions into account.