Estimation of Heterogeneous Treatment Effects on Hazard Rates

Consider a setting where a treatment that starts at some point during a spell (e.g. in unemployment) may impact on the hazard rate of the spell duration, and where the impact may be heterogeneous across subjects. We provide Monte Carlo evidence on the feasibility of estimating the distribution of treatment effects from duration data with selectivity, by means of a nonparametric maximum likelihood estimator with unrestricted numbers of mass points for the heterogeneity distribution. We find that specifying the treatment effect as homogenous may yield misleading average results if the true effects are heterogeneous, even when the sorting into treatment is appropriately accounted for. Specifying the treatment effect as a random coefficient allows for precise estimation of informative average treatment effects including the program’s overall impact on the mean duration.duration analysis, unobserved heterogeneity, program evaluation, nonparametric estimation, Monte Carlo simulation, timing of events, random effects

Additive Manufacturing for Enhanced Performance of Molds

AbstractAdditive manufactured conformal cooling channels has proved beneficial for molds used for casting. These casting tools often endure cyclic thermal influences that lead to thermal fatigue. To increase the structural resistance to thermal fatigue, the mold should be designed with some compliance for thermal expansion. This can be achieved by applying lattice structures in some sections of the mold. These structures may also be used as crack stoppers to prevent cooling fluid leakage. By use of complex internal structures, enhanced thermal management is possible. The manufacturing of molds is also faster, with less use of material

Adgangen til å fremme direkte mangelskrav på ulovfestet grunnlag: Med særlig fokus på entrepriseretten og avgjørelsen HR-2018-2256-A

Masteroppgave (60 sp)JUS396MAJU

Elevers rapportering av det psykososiale læringsmiljøet i 6. og 7. klasse, og endringer i denne tidsperioden

Hva rapporterer elever om det psykososiale læringsmiljøet når de går i 6. og 7. klasse, og hva endres i denne perioden Undersøkelsen viser at de fleste elevene har et godt læringsmiljø både i 6. og 7. klasse. Flesteparten av elevene trives sammen med både lærere og medelever, og de fleste rapporterer at tilbakemeldingen fra lærerne er god. Det er imidlertid en negativ utvikling i rapportering fra 6. til 7. klasse på nesten alle spørsmålene. Det er to eller tre rapporteringer fra elever som skiller seg ut på nesten alle de utvalgte spørsmålene i 7.klasse. Det kan se ut som at det er to, tre elever som ikke har et godt psykososialt læringsmiljø i denne klassen. Men det er ikke mulig å si med sikkerhet at disse svarene kommer fra de samme elevene. Hvis disse besvarelsene kommer fra forskjellige elever, er det kanskje flere elever som ikke har det helt bra på det psykososiale området. Undersøkelsen ble foretatt i en liten klasse, og derfor kan ikke utvalget være representativt for populasjonen. Det betyr at resultatene mine ikke kan overføres til faktisk og teoretisk populasjon, selv om det selvsagt kan gi en bitteliten indikasjon om at populasjonen kanskje kan ha den samme utviklingen i det psykososiale læringsmiljøet fra 6. til 7. klasse. Masteroppgaven kan dessuten være en liten oppvekker for flere om hvor viktig det psykososiale læringsmiljøet synes å være

Industrial Robot Collision Handling in Harsh Environments

The focus in this thesis is on robot collision handling systems, mainly collision detection and collision avoidance for industrial robots operating in harsh environments (e.g. potentially explosive atmospheres found in the oil and gas sector). Collision detection should prevent the robot from colliding and therefore avoid a potential accident. Collision avoidance builds on the concept of collision detection and aims at enabling the robot to find a collision free path circumventing the obstacle and leading to the goal position. The work has been done in collaboration with ABB Process Automation Division with focus on applications in oil and gas. One of the challenges in this work has been to contribute to safer use of industrial robots in potentially explosive environments. One of the main ideas is that a robot should be able to work together with a human as a robotic co-worker on for instance an oil rig. The robot should then perform heavy lifting and precision tasks, while the operator controls the steps of the operation through typically a hand-held interface. In such situations, when the human works alongside with the robot in potentially explosive environments, it is important that the robot has a way of handling collisions. The work in this thesis presents solutions for collision detection in paper A, B and C, thereafter solutions for collision avoidance are presented in paper D and E. Paper A approaches the problem of collision avoidance comparing an expert system and a hidden markov model (HMM) approach. An industrial robot equipped with a laser scanner is used to gather environment data on arbitrary set of points in the work cell. The two methods are used to detect obstacles within the work cell and shows a different set of strengths. The expert system shows an advantage in algorithm performance and the HMM method shows its strength in its ease of learning models of the environment. Paper B builds upon Paper A by incorporating a CAD model of the environment. The CAD model allows for a very fast setup of the expert system where no manual map creation is needed. The HMM can be trained based on the CAD model, which addresses the previous dependency on real sensor data for training purposes. Paper C compares two different world-model representation techniques, namely octrees and point clouds using both a graphics processing unit (GPU) and a central processing unit (CPU). The GPU showed its strength for uncompressed point clouds and high resolution point cloud models. However, if the resolution gets low enough, the CPU starts to outperform the GPU. This shows that parallel problems containing large data sets are suitable for GPU processing, but smaller parallel problems are still handled better by the CPU. In paper D, real-time collision avoidance is studied for a lightweight industrial robot using a development platform controller. A Microsoft Kinect sensor is used for capturing 3D depth data of the environment. The environment data is used together with an artificial potential fields method for generating virtual forces used for obstacle avoidance. The forces are projected onto the end-effector, preventing collision with the environment while moving towards the goal. Forces are also projected on to the elbow of the 7-Degree of freedom robot, which allows for nullspace movement. The algorithms for manipulating the sensor data and calculating virtual forces were developed for the GPU, this resulted in fast algorithms and is the enabling factor for real-time collision avoidance. Finally, paper E builds on the work in paper D by providing a framework for using the algorithms on a standard industrial controller and robot with minimal modifications. Further, algorithms were specifically developed for the robot controller to handle reactive movement. In addition, a full collision avoidance system for an end-user application which is very simple to implement is presented. The work described in this thesis presents solutions for collision detection and collision avoidance for safer use of robots. The work is also a step towards making businesses more competitive by enabling easy integration of collision handling for industrial robots

Complication following frenectomy: A case report

When performing a frenectomy in patients with an increased risk of exposing bone dehiscence, it is essential that the distance between the incisions is not too wide and that they are mainly made in the movable mucosa to secure optimal wound closure.publishedVersio

Estimation of heterogeneous treatment effects on hazard rates

Consider a setting where a treatment that starts at some point during a spell (e.g. in unemployment) may impact on the hazard rate of the spell duration, and where the impact may be heterogeneous across subjects. We provide Monte Carlo evidence on the feasibility of estimating the distribution of treatment effects from duration data with selectivity, by means of a nonparametric maximum likelihood estimator with unrestricted numbers of mass points for the heterogeneity distribution. We find that specifying the treatment effect as homogenous may yield misleading average results if the true effects are heterogeneous, even when the sorting into treatment is appropriately accounted for. Specifying the treatment effect as a random coefficient allows for precise estimation of informative average treatment effects including the program's overall impact on the mean duration

Human apoB contributes to increased serum total apo(a) level in LPA transgenic mice

Background The Lp(a) lipoprotein (Lp(a)) consists of the polymorphic glycoprotein apolipoprotein(a) (apo(a)), which is attached by a disulfide bond to apolipoprotein B (apoB). Apo(a), which has high homology with plasminogen, is present only in primates and hedgehogs. However, transgenic mice and rabbits with high serum apo(a) levels exist. Liver is the main site for apo(a) synthesis, but the site of removal is uncertain. To examine differences between transgenic mice expressing the LPA gene and mice capable of forming Lp(a) particles, LPA -YAC transgenic mice and hAPOB transgenic mice were crossed and their offspring examined. Results Comparison of LPA -YAC with LPA -YAC/hAPOB transgenic mice showed that LPA -YAC/hAPOB transgenic mice have higher serum total apo(a) and total cholesterol level than mice lacking the hAPOB gene. However, hepatic apo(a) mRNA level was higher in LPA -YAC transgenic mice than in LPA -YAC/hAPOB transgenic mice. Feeding of a high-cholesterol/high-fat diet to male LPA -YAC transgenic mice with or without the hAPOB gene resulted in reduced serum total apo(a) and hepatic apo(a) mRNA level. Conclusion In conclusion, the higher serum total apo(a) level in LPA -YAC/hAPOB transgenic mice than in LPA -YAC transgenic mice is not caused by increased apo(a) synthesis. Lower hepatic apo(a) mRNA level in LPA -YAC/hAPOB than in LPA -YAC transgenic mice may suggest that the increase in total apo(a) level is a result of apo(a) accumulation in serum. Furthermore, observed higher serum total cholesterol level in LPA -YAC/hAPOB transgenic mice than either in wild type or LPA -YAC transgenic mice may further suggest that human APOB transgenicity is a factor that contributes to increased serum total apo(a) and cholesterol levels. Our results on reduced serum total apo(a) and hepatic apo(a) mRNA levels in HCHF fed male LPA -YAC transgenic mice confirm earlier findings in females, and show that there are no sex difference in mechanisms for lowering apo(a) level in response to HCHF feeding

Activity of peroxisomal enzymes, and levels of polyamines in LPA-transgenic mice on two different diets

BACKGROUND: In man, elevated levels of plasma lipoprotein (a)(Lp(a)) is a cardiovascular risk factor, and oxidized phospholipids are believed to play a role as modulators of inflammatory processes such as atherosclerosis. Polyamines are potent antioxidants and anti-inflammatory agents. It was therefore of interest to examine polyamines and their metabolism in LPA transgenic mice. Concentration of the polyamines putrescine, spermidine and spermine as well as the activity of peroxisomal polyamine oxidase and two other peroxisomal enzymes, acyl-CoA oxidase and catalase were measured. The mice were fed either a standard diet or a diet high in fat and cholesterol (HFHC). Some of the mice in each feeding group were in addition given aminoguanidine (AG), a specific inhibitor of diamine oxidase, which catalyses degradation of putrescine, and also inhibits non-enzymatic glycosylation of protein which is implicated in the aetiology of atherosclerosis in diabetic patients. Non-transgenic mice were used as controls. RESULTS: Intestinal peroxisomal polyamine oxidase activity was significantly higher in LPA transgenic mice than in the non-transgenic mice, while intestinal peroxisomal catalase activity was significantly lower. Hepatic β-oxidation increased in Lp(a) transgenic mice fed the HFHC diet, but not in those on standard diet. Hepatic spermidine concentration was increased in all mice fed the HFHC diet compared to those fed a standard diet, while spermine concentration was decreased. With exception of the group fed only standard diet, transgenic mice showed a lower degree of hepatic steatosis than non-transgenic mice. AG had no significant effect on hepatic steatosis. CONCLUSION: The present results indicate a connection between peroxisomal enzyme activity and the presence of the human LPA gene in the murine genome. The effect may be a result of changes in oxidative processes in lipid metabolism rather than resulting from a direct effect of the LPA construct on the peroximal gene expression