2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC), 2009
THE Siemens HRRT scanner is a complex PET tomograph, using 8 LSO/LYSO panel detectors and Depth O... more THE Siemens HRRT scanner is a complex PET tomograph, using 8 LSO/LYSO panel detectors and Depth Of Interaction(DOI) with a total of 119908 detector crystals. The Direct Normalization (DN) is the standard method used for sinogram-mode reconstruction. This paper investigates the use of an improved component-based normalization method for HRRT sinogram reconstruction. This method is originally used for MOLAR LOR
Parameter assessment for simulation of biomass production and nitrogen uptake in winter rape. CT ... more Parameter assessment for simulation of biomass production and nitrogen uptake in winter rape. CT PETERSEN, U JORGENSEN, H SVENDSEN ...
A multicenter study is under way to investigate the efficacy of allografting of embryonic mesence... more A multicenter study is under way to investigate the efficacy of allografting of embryonic mesencephalic neurons in a pig model of Parkinson's disease. We have first established that a stable parkinsonian syndrome can be established by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication of adult male Göttingen minipigs. We are now using positron emission tomography (PET) methods for testing the physiological responses to MPTP intoxication and the time course of the response to several treatment strategies. We now report preliminary results obtained in 11 pigs employed in the initial phase of the study; the completed study shall ultimately include 30 pigs. Animals were randomly assigned to one of five groups: 1) Control, 2) MPTP intoxication, 3) MPTP intoxication followed by allograft, 4) MPTP intoxication followed by allograft with immunosuppression, and 5) MPTP intoxication followed by allograft with immunosuppression and co-grafting of immortalized HiB5 cells, whic...
The SVAT model DAISY is modified to be able to utilize remote sensing (RS) data in order to impro... more The SVAT model DAISY is modified to be able to utilize remote sensing (RS) data in order to improve prediction of evapotranspiration and photosynthesis at plot scale. The link between RS data and the DAISY model is the development of the minimum, unstressed, canopy resistance rcmin during the growing season. Energy balance processes are simulated by applying resistance networks and
Abstract Field experiments were carried out to assess the nitrogen use efficiency (NUE) of two fu... more Abstract Field experiments were carried out to assess the nitrogen use efficiency (NUE) of two furtigation treatments (Static and Dynamic) in comparison with a Non-Irrigated/Non-Fertiliscd (MM) and an lrrigated/Non-Fcrtilised (INF) control. In the Dynamic fertigation ...
ABSTRACT For large scale hydrological modeling, the accuracy of the models used is a trade-off wi... more ABSTRACT For large scale hydrological modeling, the accuracy of the models used is a trade-off with the computational requirements. The models that perform well on the daily/meter scale may not perform well when applied at the yearly/kilometer scale. We compare two models of water flow and nitrate and bromide transport in a tile drained soil. The first model is based on a 2D grid with an explicit drain node, here called the Dynamic Drainage Model (DDM). The second and less computationally expensive model is based on an 1D vertical discretization where the horizontal flow is included as a sink term based on the Hooghoudt theory, here called the Hooghoudt Drainage Model (HDM). Both are based on Finite Volume Method solutions to Richard's equation and to the advection-dispersion equation (ADE), and embedded within the Daisy agro-ecological model, which includes the nitrogen cycle. The two models are run with 10 years of weather data and three different lower boundary conditions. Losses of water, nitrogen, and bromide to both drain pipes and deep percolation/leaching are compared between the models, at daily and yearly timescales. In no case do we find the discrepancy large enough to warrant a rejection of the use of the faster HDM instead of DDM. For the daily timescale, we find in general a higher Nash-Sutcliffe efficiency coefficient for water (0.98 – 1.00) than for nitrate (0.97 – 1.00), and the lowest for bromide (0.95 – 1.00). The results are explained with a low concentration gradient along the water flow pathway towards the drain.
Land use change alters water and element cycles, but the changes in these cycles after conversion... more Land use change alters water and element cycles, but the changes in these cycles after conversion, for example, from cropland to forest are not fully described in hydrological and nutrient transport models, which usually describe either cropland or forest stands. In the European Union future afforestation is likely to occur on abandoned cropland, and evaluation of the future impacts of this land use change will require projections with models that include combined cropland-forest modules. This study used the agro-based DAISY model (Version 4.93) to investigate changes in the soil water balance over four decades following afforestation of a homogeneous area of former arable land on a sandy loam in Denmark. Hydrological data collected during nine hydrological years (April 2001-March 2010) were used to test the DAISY model. Monthly data on soil water content at 0-90 cm used for calibration were available from April 2001 to December 2002 for six monoculture stands of oak (age 8, 22 and 31 years) and Norway spruce (age 4, 13 and 32 years). Model performance was evaluated by considering uncertainties in model inputs using the Generalised Likelihood Uncertainty Estimation (GLUE) procedure. The GLUE estimates obtained (uncertainty bands 5% and 95%) agreed satisfactorily with measured monthly soil water content during the calibration period (April 2001-December 2002. Similarly, in the oldest oak stand, long-term monitoring observations and predictions of monthly water content were in satisfactory agreement during the period January 2003-March 2010). Sensitivity analysis showed that the DAISY model was most sensitive to the potential evapotranspiration factor and soil hydraulic parameters included in the Campbell model. Simulation results during nine hydrological years showed that 16-25% of incoming precipitation led to water recharge in the spruce stands, while the corresponding range for oak stands was 25-27%. A 35-year DAISY simulation revealed that Norway spruce consumed more water than oak, with differences in annual water recharge in the range 31-174 mm year À1 and with greater differences in rainy years (precipitation >900 mm year À1 ).
Proceedings of SPIE - The International Society for Optical Engineering, 2004
A method for precise and sensitive organ specific quantification of 124I (124IdUR) activities in ... more A method for precise and sensitive organ specific quantification of 124I (124IdUR) activities in small animals has been developed. The method is based upon high precision co-registration between PET and MR imagery, utilizing an innovative mouse fixation system with external point sources visible in both modalities. The methodology is generic, and thus can easily be extended to other types of
A unique integrated modelling system has been developed and applied for environmental assessment ... more A unique integrated modelling system has been developed and applied for environmental assessment studies in connection with the Gabcikovo hydropower scheme along the Danube.
2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC), 2009
THE Siemens HRRT scanner is a complex PET tomograph, using 8 LSO/LYSO panel detectors and Depth O... more THE Siemens HRRT scanner is a complex PET tomograph, using 8 LSO/LYSO panel detectors and Depth Of Interaction(DOI) with a total of 119908 detector crystals. The Direct Normalization (DN) is the standard method used for sinogram-mode reconstruction. This paper investigates the use of an improved component-based normalization method for HRRT sinogram reconstruction. This method is originally used for MOLAR LOR
Parameter assessment for simulation of biomass production and nitrogen uptake in winter rape. CT ... more Parameter assessment for simulation of biomass production and nitrogen uptake in winter rape. CT PETERSEN, U JORGENSEN, H SVENDSEN ...
A multicenter study is under way to investigate the efficacy of allografting of embryonic mesence... more A multicenter study is under way to investigate the efficacy of allografting of embryonic mesencephalic neurons in a pig model of Parkinson's disease. We have first established that a stable parkinsonian syndrome can be established by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxication of adult male Göttingen minipigs. We are now using positron emission tomography (PET) methods for testing the physiological responses to MPTP intoxication and the time course of the response to several treatment strategies. We now report preliminary results obtained in 11 pigs employed in the initial phase of the study; the completed study shall ultimately include 30 pigs. Animals were randomly assigned to one of five groups: 1) Control, 2) MPTP intoxication, 3) MPTP intoxication followed by allograft, 4) MPTP intoxication followed by allograft with immunosuppression, and 5) MPTP intoxication followed by allograft with immunosuppression and co-grafting of immortalized HiB5 cells, whic...
The SVAT model DAISY is modified to be able to utilize remote sensing (RS) data in order to impro... more The SVAT model DAISY is modified to be able to utilize remote sensing (RS) data in order to improve prediction of evapotranspiration and photosynthesis at plot scale. The link between RS data and the DAISY model is the development of the minimum, unstressed, canopy resistance rcmin during the growing season. Energy balance processes are simulated by applying resistance networks and
Abstract Field experiments were carried out to assess the nitrogen use efficiency (NUE) of two fu... more Abstract Field experiments were carried out to assess the nitrogen use efficiency (NUE) of two furtigation treatments (Static and Dynamic) in comparison with a Non-Irrigated/Non-Fertiliscd (MM) and an lrrigated/Non-Fcrtilised (INF) control. In the Dynamic fertigation ...
ABSTRACT For large scale hydrological modeling, the accuracy of the models used is a trade-off wi... more ABSTRACT For large scale hydrological modeling, the accuracy of the models used is a trade-off with the computational requirements. The models that perform well on the daily/meter scale may not perform well when applied at the yearly/kilometer scale. We compare two models of water flow and nitrate and bromide transport in a tile drained soil. The first model is based on a 2D grid with an explicit drain node, here called the Dynamic Drainage Model (DDM). The second and less computationally expensive model is based on an 1D vertical discretization where the horizontal flow is included as a sink term based on the Hooghoudt theory, here called the Hooghoudt Drainage Model (HDM). Both are based on Finite Volume Method solutions to Richard's equation and to the advection-dispersion equation (ADE), and embedded within the Daisy agro-ecological model, which includes the nitrogen cycle. The two models are run with 10 years of weather data and three different lower boundary conditions. Losses of water, nitrogen, and bromide to both drain pipes and deep percolation/leaching are compared between the models, at daily and yearly timescales. In no case do we find the discrepancy large enough to warrant a rejection of the use of the faster HDM instead of DDM. For the daily timescale, we find in general a higher Nash-Sutcliffe efficiency coefficient for water (0.98 – 1.00) than for nitrate (0.97 – 1.00), and the lowest for bromide (0.95 – 1.00). The results are explained with a low concentration gradient along the water flow pathway towards the drain.
Land use change alters water and element cycles, but the changes in these cycles after conversion... more Land use change alters water and element cycles, but the changes in these cycles after conversion, for example, from cropland to forest are not fully described in hydrological and nutrient transport models, which usually describe either cropland or forest stands. In the European Union future afforestation is likely to occur on abandoned cropland, and evaluation of the future impacts of this land use change will require projections with models that include combined cropland-forest modules. This study used the agro-based DAISY model (Version 4.93) to investigate changes in the soil water balance over four decades following afforestation of a homogeneous area of former arable land on a sandy loam in Denmark. Hydrological data collected during nine hydrological years (April 2001-March 2010) were used to test the DAISY model. Monthly data on soil water content at 0-90 cm used for calibration were available from April 2001 to December 2002 for six monoculture stands of oak (age 8, 22 and 31 years) and Norway spruce (age 4, 13 and 32 years). Model performance was evaluated by considering uncertainties in model inputs using the Generalised Likelihood Uncertainty Estimation (GLUE) procedure. The GLUE estimates obtained (uncertainty bands 5% and 95%) agreed satisfactorily with measured monthly soil water content during the calibration period (April 2001-December 2002. Similarly, in the oldest oak stand, long-term monitoring observations and predictions of monthly water content were in satisfactory agreement during the period January 2003-March 2010). Sensitivity analysis showed that the DAISY model was most sensitive to the potential evapotranspiration factor and soil hydraulic parameters included in the Campbell model. Simulation results during nine hydrological years showed that 16-25% of incoming precipitation led to water recharge in the spruce stands, while the corresponding range for oak stands was 25-27%. A 35-year DAISY simulation revealed that Norway spruce consumed more water than oak, with differences in annual water recharge in the range 31-174 mm year À1 and with greater differences in rainy years (precipitation >900 mm year À1 ).
Proceedings of SPIE - The International Society for Optical Engineering, 2004
A method for precise and sensitive organ specific quantification of 124I (124IdUR) activities in ... more A method for precise and sensitive organ specific quantification of 124I (124IdUR) activities in small animals has been developed. The method is based upon high precision co-registration between PET and MR imagery, utilizing an innovative mouse fixation system with external point sources visible in both modalities. The methodology is generic, and thus can easily be extended to other types of
A unique integrated modelling system has been developed and applied for environmental assessment ... more A unique integrated modelling system has been developed and applied for environmental assessment studies in connection with the Gabcikovo hydropower scheme along the Danube.
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Papers by Søren Hansen