Field experiments in labor economics

In this thesis I show with three studies how field experiments can enhance our understanding of labor markets. Economists traditionally assume that individuals exclusively respond to monetary incentives. As a consequence, if workers have no prospect of future employment at the firm and pay is not contingent on their performance, a wage change should not affect effort. Some economists, however, have recognized that this narrow view of human motivation may severely limit our progress in understanding incentives. In Chapters 2 and 3, I investigate the role of psychological motives like the desire to reciprocate in the context of a real‐life work environment. The first experiment explores the impact of a wage increase on work performance when there is no economic reason for workers to change their effort. I find that workers reciprocate a generous wage with higher performance, particularly those workers who care about fairness and felt underpaid prior to the wage increase. The second experiment investigates the effects of a wage cut on performance when either all workers in a team or only some of them suffer the cut. I show that a general pay cut reduces performance, while a wage cut for only some of the workers reduces their performance more than twice as much. This finding demonstrates the powerful force of social comparison and the need to build the social nature of humans into economic theory. In Chapter 4, I examine the joint effects of monetary incentives and social interaction on work performance. Many jobs offer wage schemes that create positive or negative externalities on coworkers. Whether or not workers have the possibility to interact socially at work may distort the intended incentives of these schemes. I find that under relative incentives, when own effort imposes a negative externality on the coworker’s income, social interaction works against monetary incentives and leads to low performance due to collusion. However, the more workers differ in skills the less able they are to sustain collusive agreements. In der vorliegenden Dissertation zeige ich anhand von drei Studien wie Feldexperimente unser Verständnis von Arbeitsmärkten verbessern können. Ökonomen gehen traditionell davon aus, dass Individuen ausschliesslich auf materielle Anreize reagieren. Wenn also Arbeitskräfte keine Aussicht auf eine langfristige Anstellung haben und deren Lohn nicht von der Leistung abhängt, dann sollte eine Lohnveränderung keinen Einfluss auf die Arbeitsleistung haben. Manche Ökonomen haben jedoch erkannt, dass diese Sichtweise des menschlichen Verhaltens beschränkt ist und unseren Fortschritt im Verständnis von Anreizen bremsen kann. In den Kapiteln 2 und 3 untersuche ich die Bedeutung von psychologischen Motiven wie Fairness oder Reziprozität in echten Arbeitsumgebungen. Das erste Experiment untersucht den Einfluss einer Lohnerhöhung auf die Arbeitsleistung, wenn Arbeitskräfte keinen ökonomischen Grund haben, ihren Arbeitseinsatz zu ändern. Diese Studie zeigt, dass Arbeitskräfte einen grosszügigen Lohn mit höherer Arbeitsleistung erwidern. Dies gilt besonders für diejenigen, die Fairness als wichtig empfinden und sich vor der Lohnerhöhung unterbezahlt fühlten. Das zweite Experiment untersucht die Wirkung einer Lohnkürzung auf die Arbeitsleistung, wenn entweder das ganze Team oder nur einen Teil davon betroffen ist. Diese Studie zeigt auf, dass eine generelle Lohnkürzung die Arbeitsleistung senkt, wohingegen eine Lohnkürzung nur für einzelne Arbeitskräfte deren Leistung um mehr als das Doppelte reduziert. Diese Erkenntnis unterstreicht die Bedeutung von sozialen Motiven und die Notwendigkeit einer Veränderung des Menschenbilds in der Ökonomie. In Kapitel 4 erforsche ich den gemeinsamen Einfluss von materiellen Anreizen und sozialer Interaktion auf die Arbeitsleistung. Viele Firmen bieten Lohnsysteme an, bei welchen die eigene Leistung vor‐ oder nachteilhafte Nebeneffekte auf das Einkommen der Arbeitskollegen hat. Soziale Interaktion am Arbeitsplatz kann dabei die Anreize dieser Lohnsysteme verzerren. Diese Studie findet heraus, dass bei Entlohnung der Arbeitskräfte durch Turnieranreize, d.h. wenn die eigene Leistung sich nachteilhaft auf das Einkommen der Arbeitskollegen auswirkt, soziale Interaktion die Anreize ausser Kraft setzt und zu geheimen Absprachen führt. Wenn hingegen Arbeitskräfte sehr unterschiedliche Fähigkeiten besitzen, dann sind geheime Absprachen schwieriger aufrecht zu halten

Carbon ion radiotherapy for malignant gliomas

2nd Quadrennial meeting of the World Federation of NeuroOncolog

Carbon ion radiotherapy for malignant gliomas

2nd Quadrennial meeting of the World Federation of NeuroOncolog

Carbon ion radiotherapy in NIRS

High linear energy transfer (LET) charged particle therapy with carbon ions has been of interest in the treatment of malignant tumors because of better dose localization in the tumor volume and greater biologic effectiveness. In 1984, the Heavy Ion Medical Accelerator in Chiba (HIMAC) was constructed at the National Institute of Radiological Sciences (NIRS) as a part of the comprehensive 10-year strategy for cancer control in Japan.Between June 1994 and August 2007, a total of 3,452 patients were treated by carbon ion radiotherapy at NIRS. They consisted of 564 patients with prostate cancer, 488 patients with non small cell lung cancer, 432 patients with head and neck cancer (H&N), 374 patients with bone and soft tissue (B&S) sarcomas and so on. They also consisted of 1,561 patients of phase I/II dose escalation study and 1,891 patients of phase II clinical study.For the patients with prostate, H&N and B&S sarcomas, the results of phase II study with the dose fractionation methods of 16~20 fractions through 4~5 weeks showed good local control and acceptable late normal tissue morbidity. For the patients with hepatic cell carcinoma, phase II study by two fractions is ongoing. For the patients with NSCLC, phase I/II dose escalation study of one day fraction is undergoing.The results of phase II clinical studies and preliminary results of phase I/II studies showed acceptable normal tissue acute and late reactions and good local control of the irradiated sites.日独放射線医学交流計画第１４回ワークショッ

Carbon-Ion Beam Therapy -Clinical results in Japan-

PTCOG-XXXIX-S

The Exchange of Treatment Planning Data Using RTOG Data Exchange Format

We have developed the exchange system of treatment planning data sets between multiple radiotherapy treatment planning systems (TPSs) used in our institution: a specially developed TPS for carbon ion therapy, and two commercial TPSs. The system allows mutual uses of software utilities for the carbon ion treatment planning and its analyses. Data sets including tumor and treatment target volumes, anatomical structure contours, dose distributions are exchanged through RTOG data exchange format files. The implementation issues such as the coordinate matching to CT scan images as well as the import of dose distribution are described. Several test runs showed that the coordinates of the contours and dose distributions were unaltered within a pixel size of CT image after the exchange. The system has proven to be useful in both clinical and research purpose such as image fusion and comparison of dose distributions in carbon ion treatment planning. It is also used to convert treatment planning data sets to and from DICOM RT information objects