Adaptive deterministic dyadic grids on spaces of homogeneous type

In the context of spaces of homogeneous type, we develop a method to deterministically construct dyadic grids, specifically adapted to a given combinatorial situation. This method is used to estimate vector-valued operators rearranging martingale difference sequences such as the Haar system.Comment: 17 pages, 2 figure

Exploiting regional treatment intensity for the evaluation of labour market policies

We estimate the effects of active labour market policies (ALMP) on subsequent employment by nonparametric instrumental variables and matching estimators. Very informative administrative Swiss data with detailed regional information are combined with exogenous regional variation in programme participation probabilities, which generate an instrument within well-defined local labour markets. This allows pursuing instrumental variable as well as matching estimation strategies. A specific combination of those methods identifies a new type of effect heterogeneity. We find that ALMP increases individual employment probabilities by about 15% in the short term for unemployed that may be called 'marginal' participants. The effects seem to be considerably smaller for those unemployed not marginal to the participation decision.Local average treatment effect, conditional local IV, active labour market policy, state borders, geographic variation, Switzerland, Fuller estimator

Regional treatment intensity as an instrument for the evaluation of labour market policies

The effects of active labour market policies (ALMP) on individual employment chances and earnings are evaluated by nonparametric instrumental variables based on Swiss administrative data with detailed re-gional information. Using an exogenous variation in the participation probabilities across fairly autonomous regional units (cantons) generated by the federal government, we identify the effects of ALMP by comparing individuals living in the same local labour market but in different cantons. Taking account of small sample problems occurring in IV estimation, our results suggest that ALMP increases individual employment probabilities by about 15% in the short term for a weighted subpopulation of compliers.Local average treatment effect, active labour market policy, state borders, geographic variation, weak instruments, small sample problems of IV, Switzerland, Fuller estimator

Notch2 signaling in B cell plasticity

B cells are a type of lymphocyte immune cells with important functions in humoral immunity of the adaptive immune system and are responsible for the production of antibodies. B cells also account for malignancies and autoimmune disorders. For a better understanding and treatment of these diseases, the respective B cell functions and last not least their development and origin are of crucial importance. Murine peripheral B cells can be separated into B1 and B2 cells, with B2 cells constituting the vast majority of B cells in the secondary lymphatic organs such as the spleen. B2 cells in the murine spleen are composed of follicular B (FoB) and marginal zone B (MZB) cells, which are two functionally and spatially distinct mature B cell populations. It has been shown before that Notch2 signaling plays a key role in the cell fate decision of immature transitional B cells after influx into the spleen to terminally differentiate into either a FoB or MZB cell. This process is mediated by Notch2 activation via binding its ligand DLL-1 on follicular fibroblasts. To study the effect of Notch2 activation on B cells in this follicular niche, this work makes use of a transgenic mouse model with an inducible expression of a constitutively active intracellular signaling domain of the Notch2 receptor, specifically in mature FoB cells. This work answered the open questions of what happens if a mature FoB cells receives an enduring Notch2 signal and whether this fate-decisive signaling pathway might suffice to induce a trans-differentiation towards the MZB lineage. It was observed that Notch2 activation triggered the slow process of re-programming FoB cells into bona fide MZB cells within a time window of two weeks with regard to their surface phenotype, splenic localization, immunological function and transcriptomic profile. The second part of this thesis answered the question whether the observed trans-differentiation can also occur physiologically in a non-transgenic setting of wild type mice. For this, purified FoB cells were transplanted into congenic recipient mice and their phenotype was followed up over the same time window of two weeks. The results of the adoptive transfer experiments confirmed our theory and proved a remarkable dynamic plasticity between mature FoB and MZB cells.B-Lymphozyten oder kurz B-Zellen stellen einen wichtigen Teil der Immunzellen dar und zeigen sich hauptverantwortlich für die humorale Immunantwort des adaptiven Immunsystems durch die Produktion und Sekretion von Antikörpern. B-Zellen sind in die Entstehung maligner Erkrankungen und Autoimmunkrankheiten involviert. Um diese Erkrankungen in Zukunft besser therapieren zu können, ist es von immenser Bedeutung, die einzelnen Untergruppen der B-Zellen, deren spezifische Funktionen und nicht zuletzt die Entwicklungswege der B-Zellen zu verstehen. Murine periphere B-Zellen lassen sich grob in die zwei Unterklassen der B1 und B2-Zellen teilen, wobei letztere den Großteil der B-Zellen in den sekundären Lymphorganen wie der Milz stellen. Die B2-Zellen wiederum spalten sich in Follikuläre (Fo) und Marginalzonen (MZ) B–Zellen auf, zwei Zelltypen mit unterschiedlicher immunologischer Funktion und räumlicher Lokalisation innerhalb der Milz. In der Entwicklung dieser beiden reifen B-Zell Subpopulationen hat sich der Notch2 Signalweg als entscheidender Schalter herausgestellt, mit dem sich unreife Vorläuferzellen aus dem Knochenmark bei ihrer Ankunft in der Milz zur finalen Ausdifferenzierung in entweder FoB oder MZB-Zelle entscheiden. Dabei wird der Notch-Rezeptor durch Bindung mit dem Liganden DLL-1 aktiviert, der auf follikulären Fibroblasten exprimiert wird. Um den Effekt der Aktivierung des Notch2 Signalwegs in B-Zellen in dieser follikulären Nische zu untersuchen, wurde in dieser Dissertation ein transgenes Mausmodell verwendet, in dem die Expressionen eines konstitutiv aktiven Teils des Notch2-Rezeptors spezifisch in reifen FoB-Zellen induziert werden kann. In der vorliegenden Dissertation wurde der Effekt eines andauernden Notch2 Signals auf reife FoB-Zellen untersucht, um die Frage zu beantworten, ob dieses Notch2 Signal ausreicht, um eine Transdifferenzierung zur MZB-Zellidentität anzustoßen. Die Induktion des konstitutiv aktiven Notch2 Signals war in der Tat der Auslöser eines relativ langsamen Prozesses der Transformation von FoB-Zellen in bona fide MZB-Zellen innerhalb eines Zeitfensters von zwei Wochen. Die MZB-Zell Identität konnte hinsichtlich des zellulären Phänotyps, der räumlichen Lokalisierung der Zellen innerhalb der Milzarchitektur, ihrer immunologischen Funktion sowie des Transkriptionsprofils bestätigt werden. Im zweiten experimentellen Teil dieser Arbeit wurde die Frage beantwortet, ob diese Transdifferenzierung auch im physiologischen Kontext in Wildtyp-Mäusen stattfindet. Dazu wurden aufgereinigte FoB-Zellen in nicht-transgene Empfängermäuse transplantiert und deren Phänotyp über einen Zeitraum von zwei Wochen analysiert. Die Ergebnisse des adoptiven Transfers konnten unsere Theorie bestätigen, dass eine bemerkenswerte dynamische Plastizität zwischen reifen FoB und MZB-Zellen vorliegt

Targeting Labour Market Programmes - Results from a Randomized Experiment

We evaluate a randomized experiment of a statistical support system developed to assist caseworkers in Swiss employment offices in choosing appropriate active labour market programmes for their unemployed clients. This statistical support system predicted the labour market outcome for each programme and thereby suggested an 'optimal' labour market programme for each unemployed person. The support system was piloted in several employment offices. In those pilot offices, half of the caseworkers used the system and the other half acted as control group. The allocation of the caseworkers to treatment and control group was random. The experiment was designed such that caseworkers retained full discretion about the choice of active labour market programmes, and the evaluation results showed that caseworkers largely ignored the statistical support system. This indicates that stronger incentives are needed for caseworkers to comply with statistical profiling and targeting systems.Profiling, active labour market programmes, ALMP, statistical treatment rules, unemployment, public employment services

Public Employment Services and Employers: How Important are Networks with Firms?

This paper examines whether contacts between caseworkers in public employment offices and employers impact on the reemployment chances of the unemployed they counsel. This analysis is made possible through a large administrative dataset on unemployed combined with an extensive survey of caseworkers' characteristics and their strategies. This data was created for evaluating public employment services in Switzerland. We use econometric techniques from the treatment evaluation literature to identify causal effects of a more intense employer focus of the caseworkers. The estimation results indicate that caseworkers who maintain direct contacts to firms achieve higher reintegration rates.Public employment services, new public management, employer focus

Unemployed and their Caseworkers: Should they be Friends or Foes?

In many countries, caseworkers in a public employment office have the dual roles of counselling and monitoring unemployed persons. These roles often conflict with each other leading to important caseworker heterogeneity: Some consider providing services to their clients and satisfying their demands as their primary task. Others may however pursue their strategies even against the will of the unemployed person. They may assign job assignments and labour market programmes without consent of the unemployed person. Based on a very detailed linked jobseeker-caseworker dataset, we investigate the effects of caseworkers' cooperativeness on the employment probabilities of their clients. Modified statistical matching methods reveal that caseworkers who place less emphasis on a cooperative and harmonic relationship with their clients increase their employment chances in the short and medium term.Public employment services, unemployment, statistical matching methods

Statistical Assistance for Programme Selection - For a Better Targeting of Active Labour Market Policies in Switzerland

In this paper the motivation and various concepts of statistical systems for assisting case workers in assigning unemployed persons to active labour market programmes (ALMP) are examined and the particular implementation of such a statistical system in Switzerland, which was introduced in the form of a randomized pilot study, is discussed.Statistical treatment rules, treatment effect heterogeneity

Statistical Assistance for Programme Selection - For a Better Targeting of Active Labour Market Policies in Switzerland

Arbeitsmarktpolitik, Statistisches Auswahlverfahren, Schweiz, Labour market policy, Sample selection, Switzerland

A Caseworker Like Me: Does the Similarity between Unemployed and Caseworker Increase Job Placements?

This paper examines whether the chances of job placements improve if unemployed persons are counselled by caseworkers who belong to the same social group, defined by gender, age, education, and nationality. Based on an unusually informative dataset, which links Swiss unemployed to their caseworkers, we find positive employment effects of about 4 percentage points if caseworker and unemployed belong to the same social group. Coincidence in a single characteristic, e.g. same gender of caseworker and unemployed, does not lead to detectable effects on employment. These results, obtained by statistical matching methods, are confirmed by several robustness checks.social identity, social interactions, public employment services, unemployment, gender, age, education, treatment effects, matching estimators