| 1. |
- Berglund, Anders, et al.
(författare)
-
Improved log rotation using information from a computed tomography scanner
- 2013
-
Ingår i: Computers and Electronics in Agriculture. - : Elsevier BV. - 0168-1699 .- 1872-7107. ; 90, s. 152-158
-
Tidskriftsartikel (refereegranskat)abstract
- The development of an industrial computed tomography scanner for the sawmilling industry raises the question of how to find a production strategy that uses a computed tomography scanner in the sawmill production line to its full potential. This study was focused on a Scandinavian sawmill processing Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). The potential value increase when allowing an alternative log rotation other than the horns down position was investigated using a log breakdown simulation. The resulting data was analysed with respect to the size of the log rotational step, an introduced rotational error of the sawing machine and different price differences between the quality grades. It was also of interest to define the outer log properties that characterise the logs sawn for the greatest profit return close to the horns down position compared to logs sawn for a greater profit return in a different log rotation. Such characteristics can be used to reduce the number of degrees of freedom in an optimisation and consider instead other parameters, such as positioning and sawing pattern. Other defects such as pitch pockets, splits and rot are also of interest. The results shows that there is a potential value increase when applying the log rotation that maximises the value for each log instead of processing all logs in the horns down position. However, the potential value increase depends on the rotational error of the used sawing machine and the price differences between the quality grades. The log properties that differ between logs sawn for the greatest profit return close to the horns down position compared to a different log rotation are the bow height and the log taper. Unfortunately, predictability of log rotation for greatest profit return based on the outer properties of logs is poor. It is not possible to differentiate logs which would be sawn for the greatest profit return close to the horns down position from those where a different log rotation results in the greatest profit return, based only on their outer properties.
|
|
| 2. |
- Berglund, Anders, et al.
(författare)
-
Project: CT-Pro
- 2012
-
Annan publikation (populärvet., debatt m.m.)abstract
- Projektet är finansierat av WoodWisdom-Net, VINNOVA, Fachagentur Nachwachsende Rohstoffe e. V. och medverkande företag. Syftet med projektet är att visa att det är möjligt att extrahera ut viktig och detaljerad information från en timmerstock med hjälp av en speciellt utvecklad röntgenskanner och sedan utnyttja denna information i produktionsstategier för att öka värdet i den träindustiella värdekedjan.
|
|
| 3. |
- Bertilsson, Johan, et al.
(författare)
-
Stress Levels Escalate When Repeatedly Performing Tasks Involving Threats
- 2019
-
Ingår i: Frontiers in Psychology. - : Frontiers Media SA. - 1664-1078. ; 10, s. 1562-1562
-
Tidskriftsartikel (refereegranskat)abstract
- Police work may include performing repeated tasks under the influence of psychological stress, which can affect perceptual, cognitive and motor performance. However, it is largely unknown how repeatedly performing stressful tasks physically affect police officers in terms of heart rate and pupil diameter properties. Psychological stress is commonly assessed by monitoring the changes in these biomarkers. Heart rate and pupil diameter was measured in 12 male police officers when performing a sequence of four stressful tasks, each lasting between 20 and 130 s. The participants were first placed in a dimly illuminated anteroom before allowed to enter a brightly lit room where a scenario was played out. After each task was performed, the participants returned to the anteroom for about 30 s before performing the next sequential task. Performing a repeated sequence of stressful tasks caused a significant increase in heart rate (p = 0.005). The heart rate started to increase already before entering the scenario room and was significantly larger just after starting the task than just before starting the task (p < 0.001). This pattern was more marked during the first tasks (p < 0.001). Issuance of a verbal "abort" command which terminated the tasks led to a significant increase of heart rate (p = 0.002), especially when performing the first tasks (p = 0.002). The pupil diameter changed significantly during the repeated tasks during all phases but in a complex pattern where the pupil diameter reached a minimum during task 2 followed by an increase during tasks 3 and 4 (p ≤ 0.020). During the initial tasks, the pupil size (p = 0.014) increased significantly. The results suggest that being repeatedly exposed to stressful tasks can produce in itself an escalation of psychological stress, this even prior to being exposed to the task. However, the characteristics of both the heart rate and pupil diameter were complex, thus, the findings highlight the importance of studying the effects and dynamics of different stress-generating factors. Monitoring heart rate was found useful to screen for stress responses, and thus, to be a vehicle for indication if and when rotation of deployed personnel is necessary to avoid sustained high stress exposures.
|
|
| 4. |
- Bertilsson, Johan, et al.
(författare)
-
Towards systematic and objective evaluation of police officer performance in stressful situations
- 2020
-
Ingår i: Police Practice and Research. - : Informa UK Limited. - 1561-4263 .- 1477-271X. ; 21:6, s. 655-669
-
Tidskriftsartikel (refereegranskat)abstract
- To ensure a continuous high standard of police units, it is critical to recruit people who perform well in stressful situations. Today, this selection process includes performing a large series of tests, which still may not objectively reveal a person’s capacity to handle a life-threatening situation when subjected to high levels of stress. To obtain more systematic and objective data, 12 police officers were exposed to six scenarios with varying levels of threat while their heart rate and pupil size were monitored. The scenarios were filmed and six expert evaluators assessed the performance of the police officers according to seven predefined criteria. Four of the scenarios included addressing a moderate threat level task and the scenarios were executed in a rapid sequence. Two further scenarios included a familiar firearm drill performed during high and low threat situations. The results showed that there was a large agreement between the experts in how they judged the performance of the police officers (p < 0.001). Performance increased significantly over tasks in four of the seven evaluation criteria (p ≤ 0.037). There was also a significant effect of pupil size (p = 0.004), but not heart rate, when comparing the different sequential scenarios. Moreover, a high level of threat considerably impaired the motor performance of the police officers during the firearms drill (p = 0.002). Finally, the pupil seemed to systematically dilate more when a threat appeared immediately than with a delay in the scenarios (p = 0.007). We conclude that systematic and quantitative judgments from experts provide valuable and reliable information about the performance of participants in realistic and stressful policing scenarios. Furthermore, objective physiological measures of heart rate and pupil size may help to explain and understand why performance sometimes deteriorates.
|
|
| 5. |
- Björklund, Anders, 1950-, et al.
(författare)
-
Arbetsmarknaden
- 2014. - 4
-
Bok (övrigt vetenskapligt/konstnärligt)
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Fredriksson, Anders, et al.
(författare)
-
Running wheel activity restores MPTP-induced functional deficits
- 2011
-
Ingår i: Journal of neural transmission. - Wien : Springer Science and Business Media LLC. - 0300-9564 .- 1435-1463. ; 118:3, s. 407-420
-
Tidskriftsartikel (refereegranskat)abstract
- Wheel-running and treadmill running physical exercise have been shown to alleviate parkinsonism in both laboratory and clinical studies. MPTP was administered to C57/BL6 mice using two different procedures: (a) administration of a double-dose regime (MPTP 2 × 20 or 2 × 40 mg/kg, separated by a 24-h interval), vehicle (saline 5 ml/kg) or saline (vehicle 2 × 5 ml/kg), and (b) administration of a single-dose weekly regime (MPTP 1 × 40 mg/kg) or saline (vehicle 1 × 5 ml/kg) repeated over 4 consecutive weeks. For each procedure, two different physical exercise regimes were followed: (a) after the double-dose MPTP regime, mice were given daily 30-min periods of wheel-running exercise over 5 consecutive days/week or placed in a cage in close proximity to the running wheels for 3 weeks. (b) Mice were either given wheel-running activity on 4 consecutive days (30-min periods) or placed in a cage nearby for 14 weeks. Behavioral testing was as follows: (a) after 3 weeks of exercise/no exercise, mice were tested for spontaneous motor activity (60 min) and subthreshold l-Dopa (5 mg/kg)-induced activity. (b) Spontaneous motor activity was measured on the fifth day during each of the each of the first 5 weeks (Tests 1–5), about 1 h before injections (first 4 weeks), and continued on the 5th days of the 6th to the 14th weeks (Tests 6–14). Subthreshold l-Dopa (5 mg/kg)-induced activity was tested on the 6th, 8th, 10th, 12th and 14th weeks. (b) Mice from the single-dose MPTP weekly regime were killed during the 15th week and striatal regions taken for dopamine analysis, whereas frontal and parietal cortex and hippocampus were taken for analysis of brain-derived neurotrophic factor (BDNF). It was shown that in both experiments, i.e., the double-dose regime and single-dose weekly regime of MPTP administration, physical activity attenuated markedly the MPTP-induced akinesia/hypokinesia in both the spontaneous motor activity and restored motor activity completely in subthreshold l-Dopa tests. Running wheel activity attenuated markedly the loss of dopamine due to repeated administrations of MPTP. BDNF protein level in the parietal cortex was elevated by the MPTP insult and increased further by physical exercise. Physical running wheel exercise alleviated both the functional and biomarker expressions of MPTP-induced parkinsonism.
|
|
| 9. |
- Leo, Christoph, et al.
(författare)
-
Holistic pedestrian safety assessment for average males and females
- 2023
-
Ingår i: Frontiers in Public Health. - : Frontiers Media S.A.. - 2296-2565. ; 11
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: An integrated assessment framework that enables holistic safety evaluations addressing vulnerable road users (VRU) is introduced and applied in the current study. The developed method enables consideration of both active and passive safety measures and distributions of real-world crash scenario parameters. Methods: The likelihood of a specific virtual testing scenario occurring in real life has been derived from accident databases scaled to European level. Based on pre-crash simulations, it is determined how likely it is that scenarios could be avoided by a specific Autonomous Emergency Braking (AEB) system. For the unavoidable cases, probabilities for specific collision scenarios are determined, and the injury risk for these is determined, subsequently, from in-crash simulations with the VIVA+ Human Body Models combined with the created metamodel for an average male and female model. The integrated assessment framework was applied for the holistic assessment of car-related pedestrian protection using a generic car model to assess the safety benefits of a generic AEB system combined with current passive safety structures. Results: In total, 61,914 virtual testing scenarios have been derived from the different car-pedestrian cases based on real-world crash scenario parameters. Considering the occurrence probability of the virtual testing scenarios, by implementing an AEB, a total crash risk reduction of 81.70% was achieved based on pre-crash simulations. It was shown that 50 in-crash simulations per load case are sufficient to create a metamodel for injury prediction. For the in-crash simulations with the generic vehicle, it was also shown that the injury risk can be reduced by implementing an AEB, as compared to the baseline scenarios. Moreover, as seen in the unavoidable cases, the injury risk for the average male and female is the same for brain injuries and femoral shaft fractures. The average male has a higher risk of skull fractures and fractures of more than three ribs compared to the average female. The average female has a higher risk of proximal femoral fractures than the average male. Conclusions: A novel methodology was developed which allows for movement away from the exclusive use of standard-load case assessments, thus helping to bridge the gap between active and passive safety evaluations.
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
- Philippot, Gaetan, et al.
(författare)
-
A Cannabinoid Receptor Type 1 (CB1R) Agonist Enhances the Developmental Neurotoxicity of Acetaminophen (Paracetamol)
- 2018
-
Ingår i: Toxicological Sciences. - : OXFORD UNIV PRESS. - 1096-6080 .- 1096-0929. ; 166:1, s. 203-212
-
Tidskriftsartikel (refereegranskat)abstract
- Acetaminophen (AAP; also known as paracetamol) is the most used and only recommended analgesic and antipyretic among pregnant women and young children. However, recent findings in both humans and rodents suggest a link between developmental exposure to AAP and adverse neurobehavioral effects later in life. We hypothesized that the cannabinoid receptor type 1 (CB1R) may be involved in the developmental neurotoxicity of AAP, owing to its interaction with the endocannabinoid system. Here we test if CB1R agonist WIN 55 212-2 (WIN) and AAP can interact when exposure occurs during a neurodevelopmental stage known for increased growth rate and for its vulnerability to AAP exposure. We exposed male NMRI mice on postnatal day 10 to different combinations of AAP and WIN. Adult mice, neonatally co-exposed to AAP and WIN, displayed a significant lack of habituation in the spontaneous behavior test, when compared with controls and single agent exposed mice. These adult adverse effects may at least in part be explained by a reduction of transcript levels of hippocampal synaptophysin (Syp) and tropomyosin receptor kinase B (Trkb), and cerebral cortical fatty acid amide hydroxylase (Faah), 24h after exposure. These findings are consistent with our hypothesis that AAP and WIN can interact when exposure occurs during early postnatal brain development in mice. Assuming our results are relevant for humans, they raise concerns on AAP safety because it is the only recommended analgesic and antipyretic during pregnancy and early life.
|
|
| 13. |
- Strandroth, Johan, 1978, et al.
(författare)
-
Correlation between Euro NCAP Pedestrian Test Results and Injury Severity in Injury Crashes with Pedestrians and Bicyclists in Sweden
- 2014
-
Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 2014-November:November
-
Tidskriftsartikel (refereegranskat)abstract
- Pedestrians and bicyclists account for a significant share of deaths and serious injuries in the road transport system. The protection of pedestrians in car-to-pedestrian crashes has therefore been addressed by friendlier car fronts and since 1997, the European New Car Assessment Program (Euro NCAP) has assessed the level of protection for most car models available in Europe. In the current study, Euro NCAP pedestrian scoring was compared with real-life injury outcomes in car-to-pedestrian and car-to-bicyclist crashes occurring in Sweden. Approximately 1200 injured pedestrians and 2000 injured bicyclists were included in the study. Groups of cars with low, medium and high pedestrian scores were compared with respect to pedestrian injury severity on the Maximum Abbreviated Injury Scale (MAIS)-level and risk of permanent medical impairment (RPMI). Significant injury reductions to both pedestrians and bicyclists were found between low and high performing cars. For pedestrians, the reduction of MAIS2+, MAIS3+, RPMI1+ and RPMI10+ ranged from 20-56% and was significant on all levels except for MAIS3+ injuries. Pedestrian head injuries had the highest reduction, 80-90% depending on level of medical impairment. For bicyclist, an injury reduction was only observed between medium and high performing cars. Significant injury reductions were found for all body regions. It was also found that cars fitted with autonomous emergency braking including pedestrian detection might have a 60-70% lower crash involvement than expected. Based on these results, it was recommended that pedestrian protection are implemented on a global scale to provide protection for vulnerable road users worldwide.
|
|
| 14. |
- Wallén-Mackenzie, Åsa, et al.
(författare)
-
Restricted cortical and amygdaloid removal of vesicular glutamate transporter 2 in preadolescent mice impacts dopaminergic activity and neuronal circuitry of higher brain function.
- 2009
-
Ingår i: The Journal of neuroscience : the official journal of the Society for Neuroscience. - 1529-2401 .- 0270-6474. ; 29:7, s. 2238-51
-
Tidskriftsartikel (refereegranskat)abstract
- A major challenge in neuroscience is to resolve the connection between gene functionality, neuronal circuits, and behavior. Most, if not all, neuronal circuits of the adult brain contain a glutamatergic component, the nature of which has been difficult to assess because of the vast cellular abundance of glutamate. In this study, we wanted to determine the role of a restricted subpopulation of glutamatergic neurons within the forebrain, the Vglut2-expressing neurons, in neuronal circuitry of higher brain function. Vglut2 expression was selectively deleted in the cortex, hippocampus, and amygdala of preadolescent mice, which resulted in increased locomotor activity, altered social dominance and risk assessment, decreased sensorimotor gating, and impaired long-term spatial memory. Presynaptic VGLUT2-positive terminals were lost in the cortex, striatum, nucleus accumbens, and hippocampus, and a downstream effect on dopamine binding site availability in the striatum was evident. A connection between the induced late-onset, chronic reduction of glutamatergic neurotransmission and dopamine signaling within the circuitry was further substantiated by a partial attenuation of the deficits in sensorimotor gating by the dopamine-stabilizing antipsychotic drug aripiprazole and an increased sensitivity to amphetamine. Somewhat surprisingly, given the restricted expression of Vglut2 in regions responsible for higher brain function, our analyses show that VGLUT2-mediated neurotransmission is required for certain aspects of cognitive, emotional, and social behavior. The present study provides support for the existence of a neurocircuitry that connects changes in VGLUT2-mediated neurotransmission to alterations in the dopaminergic system with schizophrenia-like behavioral deficits as a major outcome.
|
|
| 15. |
|
|
| 16. |
|
|
| 17. |
- Andersson, Roger, et al.
(författare)
-
B-field energy dependent phase lag dispersion in magnetomotive ultrasound imaging
- 2015
-
Ingår i: 2015 IEEE International Ultrasonics Symposium (IUS). - 1948-5719.
-
Konferensbidrag (refereegranskat)abstract
- Magnetomotive ultrasound imaging is an emerging technique where superparamagnetic iron oxide nanoparticles can be used as an ultrasound contrast agent. A time-varying external magnetic field acts to move tissue embedded particles, and ultrasound is used to detect the resulting tissue movement. In experimental phantom studies we have observed a phase lag dispersion in the magnetomotive response in respect to applied time-varying magnetic field (B-field). We hypothesize that this dispersion is triggered by the strength of the applied B-field in combination with concentration of embedded nanoparticles in the region. The cohort response of the nanoparticles aligns as the magnetic field gets more energetic. Moreover, the tightening of the phase response indicate an asymptotic tapering towards a phase limit.
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
- Ankarberg, Emma, et al.
(författare)
-
Increased susceptibility to adult paraoxon exposure in mice neonatally exposed to nicotine
- 2004
-
Ingår i: Toxicological Sciences. - : Oxford University Press (OUP). - 1096-6080 .- 1096-0929. ; 82:2, s. 555-561
-
Tidskriftsartikel (refereegranskat)abstract
- Low-dose exposure of neonatal mice to nicotine has earlier been shown to induce an altered behavioral response to nicotine in adulthood. Organophosphorus insecticides are known to affect the cholinergic system by inhibition of acetylcholinesterase. This study was undertaken to investigate whether neonatal exposure to nicotine makes mice more susceptible to a known cholinergic agent. Neonatal, 10-day-old, male mice were exposed to nicotine-base (33 microg/kg body weight) or saline s.c. twice daily on five consecutive days. At 5 months of age the animals were exposed to paraoxon (0.17 or 0.25 mg/kg body weight [29% and 37% inhibition of cholinesterase, respectively]) or saline sc every second day for 7 days. Before the first paraoxon injection, the animals were observed for spontaneous motor behavior. The spontaneous motor behavior test did not reveal any differences in behavior between the treatment groups. Immediately after the spontaneous behavior test, the animals received the first injection of paraoxon and were observed for acute effects of paraoxon on spontaneous motor behavior. The acute response to paraoxon in the spontaneous motor behavior test was a decreased level of activity in mice neonatally exposed to nicotine. Control animals showed no change in activity. Two months after the paraoxon treatment, the animals were again tested for spontaneous motor behavior. Animals neonatally exposed to nicotine and exposed to paraoxon as adults showed a deranged spontaneous motor behavior, including hyperactivity and lack of habituation.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
|
|
| 25. |
- Ankarberg, Emma, et al.
(författare)
-
Neurobehavioural defects in adult mice neonatally exposed to nicotine: changes in nicotine-induced behaviour and maze learning performance
- 2001
-
Ingår i: Behavioural Brain Research. - 0166-4328 .- 1872-7549. ; 123:2, s. 185-192
-
Tidskriftsartikel (refereegranskat)abstract
- Neonatal exposure to low doses of nicotine has been shown to disturb the development of low-affinity nicotinic binding sites in the cerebral cortex and to elicit a deviant behavioural response to nicotine in adult mice. In this study, 10-day-old male NMRI mice were exposed to one of three different doses of nicotine (3.3, 33, or 66 μg nicotine-base/kg body wt.) s.c. twice daily on 5 consecutive days to study dose–response effects of nicotine on adult spontaneous and nicotine-induced motor behaviour. The nicotine-induced behaviour test revealed a hypoactive response to nicotine in 4-month-old mice neonatally exposed to 33 or 66 μg nicotine-base, whereas the response to nicotine in control animals and mice exposed to 3.3 μg nicotine-base was an increased activity. Learning and memory functions were also investigated in adult animals neonatally exposed to 66 μg nicotine-base/kg body wt. in the same manner, in the Morris water maze and in the Radial arm maze. In the swim maze and the Radial arm maze tests, no significant differences were observed between nicotine-treated and control animals at the age of 4 months. At 7 months, however, a significant difference in performance was evident, indicating a time-response/time-dependent effect. Furthermore, it was shown that in mice exposed neonatally to a nicotine dose known to inhibit the development of the nicotinic low affinity-binding site (LA), the response to nicotine could not cause any increase in spontaneous motor activity as seen in controls.
|
|
| 26. |
- Anton, Nicholas, et al.
(författare)
-
AXIAL TURBINE DESIGN FOR A TWIN-TURBINE HEAVY-DUTY TURBOCHARGER CONCEPT
- 2018
-
Ingår i: PROCEEDINGS OF THE ASME TURBO EXPO. - : ASME Press. - 9780791851005
-
Konferensbidrag (refereegranskat)abstract
- In the process of evaluating a parallel twin-turbine pulse-turbocharged concept, the results considering the turbine operation clearly pointed towards an axial type of turbine. The radial turbine design first analyzed was seen to suffer from sub-optimum values of flow coefficient, stage loading and blade speed-ratio. Modifying the radial turbine by both assessing the influence of "trim" and inlet tip diameter all concluded that this type of turbine is limited for the concept. Mainly, the turbine stage was experiencing high values of flow coefficient, requiring a more high flowing type of turbine. Therefore, an axial turbine stage could be feasible as this type of turbine can handle significantly higher flow rates very efficiently. Also, the design spectrum is broader as the shape of the turbine blades is not restricted by a radially fibred geometry as in the radial turbine case. In this paper, a single stage axial turbine design is presented. As most turbocharger concepts for automotive and heavy-duty applications are dominated by radial turbines, the axial turbine is an interesting option to be evaluated for pulse charged concepts. Values of crank-angle-resolved turbine and flow parameters from engine simulations are used as input to the design and subsequent analysis. The data provides a valuable insight into the fluctuating turbine operating conditions and is a necessity for matching a pulse-turbocharged system. Starting on a 1D-basis, the design process is followed through, resulting in a fully defined 3D-geometry. The 3D-design is evaluated both with respect to FEA and CFD as to confirm high performance and durability. Turbine maps were used as input to the engine simulation in order to assess this design with respect to "on-engine" conditions and to engine performance. The axial design shows clear advantages with regards to turbine parameters, efficiency and tip speed levels compared to a reference radial design. Improvement in turbine efficiency enhanced the engine performance significantly. The study concludes that the proposed single stage axial turbine stage design is viable for a pulse-turbocharged six cylinder heavy-duty engine. Taking into account both turbine performance and durability aspects, validation in engine simulations, a highly efficient engine with a practical and realizable turbocharger concept resulted.
|
|
| 27. |
- Anton, Nicholas, et al.
(författare)
-
Exhaust volume dependency of turbocharger turbine design for a heavy duty otto cycle engine
- 2017
-
Ingår i: Proceedings of the ASME Turbo Expo. - : ASME Press. - 9780791850800
-
Konferensbidrag (refereegranskat)abstract
- This study is considering turbocharger turbine performance at "on-engine" conditions with respect to turbine design variables and exhaust manifold volume. The highly unsteady nature of the internal combustion engine will result in a very wide range of turbine operation, far from steady flow conditions. As most turbomachinery design work is conducted at steady state, the influence of the chosen turbine design variables on the crank-angle-resolved turbine performance will be of prime interest. In order to achieve high turbocharger efficiency with the greatest benefits for the engine, the turbine will need high efficiency at the energetic exhaust pressure pulse peak. The starting point for this paper is a target full load power curve for a heavy duty Otto-cycle engine, which will dictate an initial compressor and turbine match. Three radial turbine designs are investigated, differing with respect to efficiency characteristics, using a common compressor stage. The influence of the chosen turbine design variables considering a main contributor to unsteadiness, exhaust manifold volume, is evaluated using 1D engine simulation software. A discussion is held in conjunction with this regarding the efficiency potential of each turbine design and limitations of turbine types.
|
|
| 28. |
- Anton, Nicholas, et al.
(författare)
-
ON THE CHOICE OF TURBINE TYPE FOR A TWIN-TURBINE HEAVY-DUTY TURBOCHARGER CONCEPT
- 2018
-
Ingår i: PROCEEDINGS OF THE ASME TURBO EXPO. - : AMER SOC MECHANICAL ENGINEERS. ; 8
-
Konferensbidrag (refereegranskat)abstract
- In this study, a fundamental approach to the choice of turbocharger turbine for a pulse-charged heavy-duty diesel engine is presented. A standard six-cylinder engine build with a production exhaust manifold and a Twin-scroll turbocharger is used as a baseline case. The engine exhaust configuration is redesigned and evaluated in engine simulations for a pulse-charged concept consisting of a parallel twin-turbine layout. This concept will allow for pulse separation with minimized exhaust pulse interference and low exhaust manifold volume. This turbocharger concept is uncommon, as most previous studies have considered two stage systems, various multiple entry turbine stages etc. Even more rare is the fundamental aspect regarding the choice of turbine type as most manufacturers tend to focus on radial turbines, which by far dominate the turbochargers of automotive and heavy-duty applications. By characterizing the turbine operation with regards to turbine parameters for optimum performance found in literature a better understanding of the limitations of turbine types can be achieved. A compact and low volume exhaust manifold design is constructed for the turbocharger concept and the reference radial turbine map is scaled in engine simulations to a pre-set AFR-target at a low engine RPM. By obtaining crank-angle-resolved data from engine simulations, key turbine parameters are studied with regard to the engine exhaust pulse-train. At the energetic exhaust pressure pulse peak, the reference radial turbine is seen to operate with suboptimum values of Blade-Speed-Ratio, Stage Loading and Flow Coefficient. The study concludes that in order to achieve high turbine efficiency for this pulse-charged turbocharger concept, a turbine with efficiency optimum towards low Blade-Speed Ratios, high Stage Loading and high Flow Coefficient is required. An axial turbine of low degree of reaction-design could be viable in this respect.
|
|
| 29. |
|
|
| 30. |
|
|
| 31. |
- Anton, Nicholas, et al.
(författare)
-
Twin-Scroll turbocharger turbine stage evaluation of experimental data and simulations
- 2018
-
Ingår i: Institution of Mechanical Engineers - 13th International Conference on Turbochargers and. - : Institution of Mechanical Engineers. - 9781510873872 ; , s. 487-502
-
Konferensbidrag (refereegranskat)abstract
- In this study a novel comparison of CFD, measured data and a ID-model is presented for a Twin-scroll turbocharger turbine stage. Both full and single admission flow divisions were taken into consideration and shown to represent "on-engine" conditions in the high and low engine rpm range respectively for a heavy-duty 6-cylinder diesel engine. With this in mind, the turbine stage was evaluated for each flow division at several rotational speeds. Both high and low pressure ratios were run. Emphasis is made on high pressure ratios as it is the most relevant case with regards to the energy levels of the exhaust flow. The purpose of the study was to gain insight into the differences and similarities between gas stand measurements, a ID-model and CFD considering performance and turbine stage parameters. The study concludes that the results from the measurements in the gas stand and ID-model, obtained best correlation with the CFD results at low turbine pressure ratios. At high pressure ratios significant deviations were observed. In order to check for discrepancies, both frozen rotor and stage interfaces were considered in the CFD-model, with an additional variant taking the rotor-volute tongue clocking into account. All interfaces resulted in the same trends, although the frozen rotor approach provided the best correlation with measured data. The clocking effect was seen not to affect the results to a great extent in this case. The main difference between the CFD and measurements in combination with the ID model-prediction primarily occur at the rotor inlet. The pressures were predicted to be substantially higher by the CFD calculations due to reduced pressure losses in the volute. Especially taking effect at high turbine pressure ratios which is most relevant for turbocharger applications and therefor the mapping process in the gas stand. This can be one of the reasons for significant deviations in efficiency, turbine parameters etc. at high pressure ratios as effectively more energy will be available to the rotor for a given turbine stage pressure ratio. In general best coherence was achieved for the full admission case. Even so, trends of main parameters such as efficiency, flow capacity and turbine parameters point in the same direction comparing CFD with calculations and measured results for both full and single admission.
|
|
| 32. |
- Antonsson, Tomas, et al.
(författare)
-
Liquid Ni-Fe penetration and recrystallisation in tungsten
- 2003
-
Ingår i: International journal of refractory metals & hard materials. - 0263-4368. ; 21:3-4, s. 159-170
-
Tidskriftsartikel (refereegranskat)abstract
- Melt penetration in grain boundaries of solid tungsten has been investigated. Solid tungsten rods have been exposed to a nickel-iron melt saturated with tungsten and the penetration depth and the shape of the liquid channels have been examined. The solid tungsten samples have been treated in different ways like cold working, annealing and recrystallisation, before melt exposure. Important parameters for the penetration process are stresses, surface tensions, solution and kinetic effects. A new theoretical model for the penetration mechanism in cold worked samples is proposed. Rapid recovery of the grains in the penetrated areas of the cold worked samples was observed. This is discussed, as well.
|
|
| 33. |
- Archer, Trevor, 1949, et al.
(författare)
-
Behavioural supersensitivity following neonatal 6-hydroxydopamine : Attenuation by MK-801
- 2007
-
Ingår i: Neurotoxicity research. - 1029-8428 .- 1476-3524. ; 12:2, s. 113-124
-
Tidskriftsartikel (refereegranskat)abstract
- Male rat pups were administered 6-hydroxydopamine (6-OHDA, 75 μg, intracisternally, 30 min after desipramine, 25 mg/kg, s.c.) on Days 1 or 2 after birth, or were sham-operated (receiving vehicle). In four experiments, the acute effects of apomorphine, with or without pretreatment with MK-801 (0.03 mg/kg), upon motor activity in test chambers was measured. Acute treatment with apomorphine (0.1 mg/kg) increased locomotor, rearing and total activity markedly compared to both the acute saline administered 6-OHDA rats and the sham-operated rats administered saline. Acute MK-801 (0.03 mg/kg) co-administered shortly before (5 min) apomorphine (0.3 or 1.0 mg/kg) reduced markedly locomotion and total activity in 6-OHDA-treated and sham-operated rats. Rearing behaviour was increased in both the 6-OHDA groups of rats. Acute MK-801 increased activity in the 6-OHDA-treated rats, which was not observed in sham-operated rats. At the 0.3 and 1.0 mg/kg doses of apomorphine, neonatal 6-OHDA treament increased all three parameters of motor activity. Acute treatment with apomorphine (0.1 mg/kg) induced different effects on the motor activity of 6-OHDA-treated and sham-operated mice. In sham-operated rats apomorphine reduced motor activity during the 1st 30-min period but increased locomotion and total activity, but not rearing, during the 2nd and 3rd periods, whereas in 6-OHDA-treated rats, apomorphine increased locomotor, rearing and total activity markedly. Dopamine loss and serotonin elevation in the striatum and olfactory tubercle were confirmed. The present findings confirm the influence of non-competitive glutamate antagonists in attenuating the behavioural supersensitivity to dopamine antagonists.
|
|
| 34. |
- Archer, Trevor, 1949, et al.
(författare)
-
Delayed Exercise-Induced Functional and Neurochemical Partial Restoration Following MPTP
- 2012
-
Ingår i: Neurotoxicity research. - : Springer Science and Business Media LLC. - 1029-8428 .- 1476-3524. ; 21:2, s. 210-221
-
Tidskriftsartikel (refereegranskat)abstract
- In two experiments, MPTP was administered to C57/BL6 mice according to a single-dose weekly regime (MPTP: 1 x 30 mg/kg on the fifth day of the week, Friday, over 4 weeks) with vehicle group (Vehicle: 1 x 5 ml/kg) treated concurrently. Exercise schedules (delayed) were introduced either at the beginning of the week after the second MPTP injection (MPTP + Exercise(2) group), or at the beginning of the week after the fourth MPTP injection (MPTP + Exercise(4) group). Wheel-running was provided on the first 4 days of each week (Monday-Thursday) more than 30-min periods. In Experiment I, wheel-running exercise was introduced either after 2 or 4 weeks after MPTP/Vehicle. MPTP and Vehicle groups not provided access to the running wheels were placed in single cages within the wheel-running room over 30-min concomitantly with the wheel-running groups. In Experiment II, wheel-running exercise was introduced 2 weeks after MPTP/Vehicle but a no-exercise control group with non-revolving wheel included (MPTP-Wheel). In both experiments, spontaneous motor activity tests during 60-min intervals were performed at the end (Fridays) of weeks 1, 2, 3, 4, 6, 8, and 10, where the week on which the first injection of MPTP was the first week; in the case of weeks 1-4, this was immediately before MPTP/Vehicle injections. It was observed that the introduction of the exercise schedule after the second MPTP injection, but not after the fourth injection, restored motor activity that had been markedly elevated by the end of the tenth week. Subthreshold administration of l-dopa tests was performed after the spontaneous motor activity tests 6, 8 and 10; these indicated significant effects of exercise, MPTP + Exercise(2) group, on Tests 6 and 8, but not Test 10. The physical exercise schedule in that group also showed markedly attenuated loss of dopamine (DA). Restoration of MPTP-induced motor activity deficits and DA loss was a function of the point at which exercise was introduced, in the present case after two administrations of the neurotoxin. In Experiment II, physical exercise markedly attenuated the hypokinesic effect of MPTP in the exercise condition, MPTP-exercise, but not in the non-exercise conditions, MPTP-Cage and MPTP-Wheel, for both spontaneous motor activity and l-dopa-induced activity. MPTP-induced loss of DA was also attenuated by exercise.
|
|
| 35. |
- Archer, T., et al.
(författare)
-
Exercise alleviates Parkinsonism : clinical and laboratory evidence
- 2011
-
Ingår i: Acta Neurologica Scandinavica. - : Hindawi Limited. - 0001-6314 .- 1600-0404. ; 123:2, s. 73-84
-
Forskningsöversikt (refereegranskat)abstract
- The present review examines the putative benefits for individuals afflicted with Parkinsonism, whether in the clinical setting or in the animal laboratory, accruing from different exercise regimes. The tendency for patients with Parkinson's disease (PD) to express either normal or reduced exercise capacity appears regulated by factors such as fatigue, quality-of-life and disorder severity. The associations between physical exercise and risk for PD, the effects of exercise on idiopathic Parkinsonism and quality-of-life, the effects of exercise on animal laboratory models of Parkinsonism and dopamine (DA) loss following neurotoxic insults, and the effects of exercise on the DA precursor, L-Dopa, efficacy are examined. It would appear to be case that in view of the particular responsiveness of the dopaminergic neurons to exercise, the principle of 'use it or lose' may be of special applicability among PD patients.
|
|
| 36. |
- Archer, Trevor, 1949, et al.
(författare)
-
Functional consequences of iron overload in catecholaminergic interactions: the Youdim factor
- 2007
-
Ingår i: Neurochemical Research. - : Springer Science and Business Media LLC. - 0364-3190 .- 1573-6903. ; 32:10, s. 1625-1639
-
Forskningsöversikt (refereegranskat)abstract
- The influence of postnatal iron overload upon implications of the functional and interactive role of dopaminergic and noradrenergic pathways that contribute to the expressions of movement disorder and psychotic behaviours in mice was studied in a series of experiments. (1) Postnatal iron overload at doses of 7.5 mg/kg (administered on Days 10–12 post partum) and above, invariably induced a behavioural syndrome consisting of an initial (1st 20–40 min of a 60-min test session) hypoactivity followed by a later (final 20 min of a 60-min test session) hyperactivity, when the mice were tested at adult ages (age 60 days or more). (2) Following postnatal iron overload, subchronic treatment with the neuroleptic compounds, clozapine and haloperidol, dose-dependently reversed the initial hypoactivity and later hyperactivity induced by the metal. Furthermore, DA D2 receptor supersensitivity (as assessed using the apomorphine-induced behaviour test) was directly and positively correlated with iron concentrations in the basal ganglia. (3) Brain noradrenaline (NA) denervation, using the selective NA neurotoxin, DSP4, prior to administration of the selective DA neurotoxin, MPTP, exacerbated both the functional (hypokinesia) and neurochemical (DA depletion) effects of the latter neurotoxin. Treatment with L-Dopa restored motor activity only in the animals that had not undergone NA denervation. These findings suggest an essential neonatal iron overload, termed “the Youdim factor”, directing a DA–NA interactive component in co-morbid disorders of nigrostriatal-limbic brain regions.
|
|
| 37. |
- Archer, Trevor, 1949, et al.
(författare)
-
Fusion models and “Fusioning” in Parkinsonism: Protection and Restoration by exercise.
- 2014
-
Ingår i: Kostrzewa R.M. (ed). Handbook of Neurotoxicity. - New York : Springer. - 9781461458357 ; , s. 2047-2063
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Fusion models, or the “fusioning” of models, of Parkinson’s disease (PD) to attain the sufficiency of disorder etiopathogenesis have spurred the development of laboratory models incorporating neurotoxin treatments in combination with genetic manipulations of animals studied. The present review describes fusion from two directions: (i) through the fusioning of neurotoxin and genetic models, and, It was observed that wheel-running exercise (four 30-min sessions/week) attenuated the motor deficits, both assessed as distance run in the running wheels and as locomotor, rearing and total activity counts in the motor activity test chambers, and the dopamine (DA) loss induced by the DA neurotoxin, MPTP compared with the no exercise MPTP group (one 30-min session/week).
|
|
| 38. |
- Archer, Trevor, 1949, et al.
(författare)
-
Influence of noradrenaline denervation on MPTP-induced deficits in mice
- 2006
-
Ingår i: Journal of neural transmission. - : Springer Science and Business Media LLC. - 0300-9564 .- 1435-1463. ; 113:9, s. 1119-1129
-
Tidskriftsartikel (refereegranskat)abstract
- C57/BL6 mice were administered either DSP4 (50 mg/kg, s.c., 30 min after injection of zimeldine, 20 Cemg/kg, s.c.) or vehicle (saline) at 63 days of age. Three weeks later, one group (n = 10) of DSP4-treated and one group of vehicle-treated mice were administered MPTP (2 x 40 mg/kg, s.c., 24 hours between injections; the High dose groups), one group (n = 10) of DSP4-treated and one group of vehicle-treated mice were administered MPTP (2 x 20 mg/kg, s.c., 24 hours between injections; the Low dose groups), and one group (n = 10) of DSP4-treated and one group of vehicle-treated mice were administered vehicle. Three weeks later, all six groups were tested in motor activity test chambers, followed by injections of L-Dopa (20 mg/kg, s.c.), and then tested over a further 360 min in the activity test chambers. It was found that pretreatment with the selective NA neurotoxin, DSP4, deteriorated markedly the dose-dependent motor activity deficits observed in the vehicle pretreated MPTP treated mice. These 'ultra-deficits' in the spontaneous motor behaviour of MPTP-treated mice were observed over all three parameters: locomotion, rearing and total activity, and were restricted to the 1(st) and 2(nd) 20-min periods. Administration of L-Dopa (20 mg/kg) following the 60-min testing of spontaneous behaviour restored the motor activity of Vehicle + MPTP treated mice (neither the Vehicle + MPTP-Low nor the Vehicle + MPTP-High groups differed from the Vehicle-Vehicle group, here) but failed to do so in the DSP4 pretreated mice. Here, a dose-dependent deficit of L-Dopa-induced motor activity (over all three parameters) was obtained thereby offering further evidence of an 'ultra-deficit' of function due to previous denervation of the NA terminals. The present findings support the notion that severe damage to the locus coeruleus noradrenergic system, through systemic DSP4, disrupts the facilitatory influence on the nigrostriatal DA system, and interferes with the ability of the nigrostriatal pathway to compensate for or recover from marked injury, MPTP treatment.
|
|
| 39. |
- Archer, Trevor, 1949, et al.
(författare)
-
Influence of Physical Exercise on Neuroimmunological Functioning and Health : Aging and Stress
- 2011
-
Ingår i: Neurotoxicity research. - : Springer Science and Business Media LLC. - 1029-8428 .- 1476-3524. ; 20:1, s. 69-83
-
Tidskriftsartikel (refereegranskat)abstract
- Chronic and acute stress, with associated pathophysiology, are implicated in a variety of disease states, with neuroimmunological dysregulation and inflammation as major hazards to health and functional sufficiency. Psychosocial stress and negative affect are linked to elevations in several inflammatory biomarkers. Immunosenescence, the deterioration of immune competence observed in the aged aspect of the life span, linked to a dramatic rise in morbidity and susceptibility to diseases with fatal outcomes, alters neuroimmunological function and is particularly marked in the neurodegenerative disorders, e.g., Parkinson's disease and diabetes. Physical exercise diminishes inflammation and elevates agents and factors involved in immunomodulatory function. Both the alleviatory effects of life-long physical activity upon multiple cancer forms and the palliative effects of physical activity for individuals afflicted by cancer offer advantages in health intervention. Chronic conditions of stress and affective dysregulation are associated with neuroimmunological insufficiency and inflammation, contributing to health risk and mortality. Physical exercise regimes have induced manifest anti-inflammatory benefits, mediated possibly by brain-derived neurotrophic factor. The epidemic proportions of metabolic disorders, obesity, and diabetes demand attention; several variants of exercise regimes have been found repeatedly to induce both prevention and improvement under both laboratory and clinical conditions. Physical exercise offers a unique non-pharmacologic intervention incorporating multiple activity regimes, e.g., endurance versus resistance exercise that may be adapted to conform to the particular demands of diagnosis, intervention and prognosis inherent to the staging of autoimmune disorders and related conditions.
|
|
| 40. |
- Archer, Trevor, 1949, et al.
(författare)
-
Physical exercise as Intervention in Parkinsonism
- 2013
-
Ingår i: Handbook of Neurotoxicity. - New York : Springer Science+Business Media. ; , s. 2255-2280
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Physical exercise, particularly for individuals with sedentary occupations and independent of activity type, offers probably the most effective health-ensuring policy available. The associations between physical exercise and symptoms/biomarkers of idiopathic Parkinsonism and animal models of Parkinson’s disease (PD), quality of life and self-reliance, disorder progression, and risk factors all support the contention that activity provides for an improved prognosis. In the present treatise, mice treated with the selective dopamine neurotoxin (1-methyl- 4-phenyl-1,2,3,6-tetrahydropyridine, 3 x 30 mg/kg once each week over three weeks), or Vehicle, were given access to running-wheel exercise from the week following the first injection of MPTP onwards: the MPTP-Exercise group received four 30-min sessions in the running wheels (Mondays to Thursdays), whereas the MPTP No-exercise and Vehicle groups received a single session each week (Wednesdays). It was observed that the MPTP+ Exercise group increased the distance run on each Wednesday 30-min session incrementally, whereas the MPTP No-exercise and Vehicle groups remained at the same distance throughout; similarly, during the 10-min test session on Fridays, prior to the tests of motor activity, the MPTP+ Exercise group increased the distance run on each successive occasion but the MPTP No-exercise and Vehicle groups did not. In the tests of spontaneous motor activity, running- wheel exercise over 4 days/week (30 min, Mon.–Thurs.) improved all three parameters of motor activity, locomotion, rearing, and total activity, in the activity test chamber during test weeks 2–7, compared to the MPTP group following the MPTP administration. In the L-Dopa-induced activity test, running-wheel exercise over 4 days/week enhanced locomotor and rearing but not total activity following the subthreshold dose of L-Dopa for the MPTP+Exercise group but not the MPTP No-exercise group. Running-wheel exercise over 4 days/week increased the DA concentrations in the striatum of MPTP+ Exercise mice.
|
|
| 41. |
- Archer, Trevor, 1949, et al.
(författare)
-
Physical Exercise Attenuates MPTP-Induced Deficits in Mice
- 2010
-
Ingår i: Neurotoxicity research. - : Springer Science and Business Media LLC. - 1029-8428 .- 1476-3524. ; 18:3-4, s. 313-327
-
Tidskriftsartikel (refereegranskat)abstract
- Two experiments were performed to investigate the effects of physical exercise upon the hypokinesia induced by two different types of MPTP administration to C57/BL6 mice. In the first, mice were administered either the standard MPTP dose (2 x 20 or 2 x 40 mg/kg, 24-h interval) or vehicle (saline, 5 ml/kg); and over the following 3 weeks were given daily 30-min period of wheel running exercise over five consecutive days/week or placed in a cage in close proximity to the running wheels. Spontaneous motor activity testing in motor activity test chambers indicated that exercise attenuated the hypokinesic effects of both doses of MPTP upon spontaneous activity or subthreshold l-Dopa-induced activity. In the second experiment, mice were either given wheel running activity on four consecutive days (30-min period) or placed in a cage nearby and on the fifth day, following motor activity testing over 60 min, injected with either MPTP (1 x 40 mg/kg) or vehicle. An identical procedure was maintained over the following 4 weeks with the exception that neither MPTP nor vehicle was injected after the fifth week. The animals were left alone (without either exercise or MPTP) and tested after 2- and 4-week intervals. Weekly exercise blocked, almost completely, the progressive development of severe hypokinesia in the MPTP mice and partially restored normal levels of activity after administration of subthreshold l-Dopa, despite the total absence of exercise following the fifth week. In both experiments, MPTP-induced loss of dopamine was attenuated by the respective regime of physical exercise with dopamine integrity more effectively preserved in the first experiment. The present findings are discussed in the context of physical exercise influences upon general plasticity and neuroreparative propensities as well as those specific for the nigrostriatal pathway.
|
|
| 42. |
- Archer, Trevor, 1949, et al.
(författare)
-
Restoration of MPTP-induced deficits by Exercise and Milmed® Co-treatment
- 2014
-
Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 2:e531
-
Tidskriftsartikel (refereegranskat)abstract
- 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) induces permanent neurochemical and functional deficits. Following the administration of either two or four injections of the dopamine neurotoxin, MPTP, at a dose of 40 mg/kg, C57/BL6 mice were given access to running-wheels (30-min sessions, four times/week, Monday–Thursday) and treatment with the treated yeast, Milmed® (four times/week, Monday–Thursday), or simply running-wheel exercise by itself, over ten weeks. It was observed that the combination of physical exercise and Milmed® treatment, the MPTP + Exercise + Yeast (MC) group [MPTP + Ex- ercise + Milmed® (MC)], restored spontaneous motor activity markedly by test day 10, restored completely subthreshold L-Dopa-induced activity, and dopamine concentration to 76% of control values, in the condition wherein two adminis- trations of MPTP (2 × 40 mg/kg) were given prior to initiation of exercise and/or Milmed® treatment. Physical exercise by itself, MPTP + Exercise (MC) group, attenuated these deficits only partially. Administration of MPTP four times (i.e., 40 mg/kg, s.c., once weekly over four weeks for a total of 160 mg/kg, MPTP + Exer- cise + Yeast (MC) group [MPTP + Exercise + Milmed® (SC)] and MPTP + Exercise (SC), induced a lesioning effect that was far too severe for either exercise alone or the exercise + Milmed® combination to ameliorate. Nevertheless, these findings indicate a powerful effect of physical exercise reinforced by Milmed® treatment in restoring MPTP-induced deficits of motor function and dopamine neurochemistry in mice.
|
|
| 43. |
- Archer, Trevor, 1949, et al.
(författare)
-
The Yeast Product Milmed Enhances the Effect of Physical Exercise on Motor Performance and Dopamine Neurochemistry Recovery in MPTP-Lesioned Mice
- 2013
-
Ingår i: Neurotoxicity Research. - : Springer Science and Business Media LLC. - 1029-8428 .- 1476-3524. ; 24:3, s. 393-406
-
Tidskriftsartikel (refereegranskat)abstract
- Both clinical and laboratory studies have demonstrated that different types of physical exercise may alleviate Parkinsonism yet evidence for complete restoration of motor function and biomarker integrity are difficult to identify. MPTP (1 x 30 mg/kg, s.c., 4 groups) or saline (vehicle 1 x 5 ml/kg, s.c., 1 group) were administered in a single dose regime over three consecutive weeks on Fridays. Three MPTP groups were given four 30-min periods/week (Mondays to Thursdays), of these two groups, MPTP + Exer + M(i) and MPTP + Exer + M(ii); the former were introduced to exercise and Milmed (oral injection) on the week following the 1st MPTP injection and the latter on the Monday prior to the 1st injection of MPTP onwards. One MPTP group, MPTP + Exer, was given access to exercise (running wheels) from the week following the 1st MPTP injection onwards. The fourth MPTP group, MPTP-NoEx, and the Vehicle group were only given access to exercise on a single day each week (Wednesdays, exercise test) from the week following the 1st MPTP injection onwards. The exercise/exercise + Milmed regime was maintained for a further 9 weeks. It was observed that exercise by itself ameliorated MPTP-induced deficits regarding motor function and dopamine loss only partially whereas in the groups combining exercise with twice weekly dosages of Milmed the MPTP-induced deficits were abolished by the 10th week of the intervention. The three main conclusions that were drawn from correlational analyses of individual mice were: (i) that DA integrity was observed to be a direct function of ability to express running exercise in a treadmill wheel-running arrangement, and (ii) that DA integrity was observed to be a direct function of the capacity for motor performance as measured by spontaneous motor activity and subthreshold l-Dopa (5 mg/kg) induced activity in the motor activity test chambers, and (iii) that the extent to which running exercise in a running wheel was predictive of later motor performance in the activity test chambers was highly convincing.
|
|
| 44. |
|
|
| 45. |
- Bengtsson, Ivar, et al.
(författare)
-
Implications of using the clinical target distribution as voxel-weights in radiation therapy optimization
- 2023
-
Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 68:9
-
Tidskriftsartikel (refereegranskat)abstract
- Objective. Delineating and planning with respect to regions suspected to contain microscopic tumor cells is an inherently uncertain task in radiotherapy. The recently proposed clinical target distribution (CTD) is an alternative to the conventional clinical target volume (CTV), with initial promise. Previously, using theCTDin planning has primarily been evaluated in comparison to a conventionally defined CTV. Wepropose to compare theCTDapproach against CTVmargins of various sizes, dependent on the threshold at which the tumor infiltration probability is considered relevant. Approach. First, a theoretical framework is presented, concerned with optimizing the trade-off between the probability of sufficient target coverage and the penalties associated with high dose. From this framework we derive conventional CTV-based planning and contrast it with theCTDapproach. The approaches are contextualized further by comparison with established methods for managing geometric uncertainties. Second, for both one- and three-dimensional phantoms, we compare a set of CTDplans created by varying the target objective function weight against a set of plans created by varying both the target weight and the CTVmargin size. Main results. The results show that CTD-based planning gives slightly inefficient trade-offs between the evaluation criteria for a case in which near-minimum target dose is the highest priority. However, in a case when sparing a proximal organ at risk is critical, theCTDis better at maintaining sufficiently high dose toward the center of the target. Significance. Weconclude that CTD-based planning is a computationally efficient method for planning with respect to delineation uncertainties, but that the inevitable effects on the dose distribution should not be disregarded.
|
|
| 46. |
|
|
| 47. |
|
|
| 48. |
|
|
| 49. |
|
|
| 50. |
- Birgner, Carolina, et al.
(författare)
-
VGLUT2 in dopamine neurons is required for psychostimulant-induced behavioural activation
- 2010
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 107:1, s. 389-394
-
Tidskriftsartikel (refereegranskat)abstract
- The “One neuron-one neurotransmitter” concept has been challenged frequently during the last three decades, and the coexistence of neurotransmitters in individual neurons is now regarded as a common phenomenon. The functional significance of neurotransmitter coexistence is, however, less well understood. Several studies have shown that a subpopulation of dopamine (DA) neurons in the ventral tegmental area (VTA) expresses the vesicular glutamate transporter 2 (VGLUT2) and has been suggested to use glutamate as a cotransmitter. The VTA dopamine neurons project to limbic structures including the nucleus accumbens, and are involved in mediating the motivational and locomotor activating effects of psychostimulants. To determine the functional role of glutamate cotransmission by these neurons, we deleted VGLUT2 in DA neurons by using a conditional gene-targeting approach in mice. A DAT-Cre/Vglut2Lox mouse line (Vglut2f/f;DAT-Cre mice) was produced and analyzed by in vivo amperometry as well as by several behavioral paradigms. Although basal motor function was normal in the Vglut2f/f;DAT-Cre mice, their risk-taking behavior was altered. Interestingly, in both home-cage and novel environments, the gene targeted mice showed a greatly blunted locomotor response to the psychostimulant amphetamine, which acts via the midbrain DA system. Our results show that VGLUT2 expression in DA neurons is required for normal emotional reactivity as well as for psychostimulant-mediated behavioral activation.
|
|
