Essays on Matching Markets

The thesis consists of three chapters in the theory of matching markets. In Chapter 2, I study a central authority's ability to commit to a publicly announced mechanism in a one-to-one agent-object matching model. The authority announces a strategy-proof mechanism and then privately selects a mechanism to initiate a matching. An agent's observation in form of the final matching has an innocent explanation (Akbarpour and Li, 2020), if given the agent's reported preferences, there is a combination with other agents' preferences leading to an identical observation under the announced mechanism. The authority can only commit up to safe deviations (Akbarpour and Li, 2020)---mechanisms that produce only observations with innocent explanations. For efficient or stable announcements, I show that no safe deviation exists if and only if the announced mechanism is dictatorial. I establish that the Deferred Acceptance (DA) Mechanism (Gale and Shapley, 1962) implies commitment to stability. Moreover, group strategy-proof and efficient announcements allow commitment to efficiency only if they are dictatorial. In Chapter 3, we study The Efficiency Adjusted Deferred Acceptance Matching Rule (EDA) which is a promising candidate mechanism for public school assignment. A potential drawback of EDA is that it could encourage students to game the system since it is not strategy-proof. However, to successfully strategize, students typically need information that is unlikely to be available to them in practice. We model school choice under incomplete information and show that EDA is regret-free truth-telling, which is a weaker incentive property than strategy-proofness and was introduced by (Fernandez, 2020). We also show that there is no efficient matching rule that weakly Pareto dominates a stable matching rule and is regret-free truth-telling. Note that without modifications the EDA as introduced by (Kesten, 2010) weakly Pareto dominates a stable matching rule, but it is not efficient. In Chapter 4, I study agents’ incentives in a one-to-one object allocation model where agents are envious. Among all agents whose assignment is tracked by some agent, the agent envies those who are matched to an object she prefers to her own assignment. Given a mechanism and agents’ actions, agent i’s envy towards agent j at object x under the induced matching is inevitable if i has no action where she does not envy j at x, given one keeps the actions of other agents unchanged. A matching mechanism is envyproof, if for each market and agent, any envy under truthful revelation of preferences is inevitable. Envy-proofness is a concept that is stronger than strategy-proofness. I show that the Top Trading Cycle (TTC) Mechanism is envy-proof. Moreover, the unique strategy-proof and stable mechanism, the Deferred Acceptance Mechanism, is not envy-proof

On the descriptive validity of ICD-10 schizophrenia: Empirical analyses in the spectrum of non-affective functional psychoses

In order to examine the descriptive validity of ICD-10 schizophrenia, 1,476 consecutively admitted in-patients were included in the present study. ICD-10 schizophrenia (n = 951) was compared with other non-affective psychotic disorders {[}persistent delusional disorders (n = 51), acute and transient psychotic disorders (n = 116) and schizoaffective disorders (n = 354)] with respect to socio-demographic, symptomatological and other clinical parameters. Analyses revealed that it is possible to distinguish schizophrenia from other non-affective psychotic disorders according to ICD-10 criteria: schizophrenic patients were characterised by more pronounced negative symptoms and a lower global functioning. They were younger than patients with persistent delusional disorders and schizoaffective disorders but older than patients with acute and transient psychotic disorders. The results are in line with a high descriptive validity of ICD-10 schizophrenia and highlight the importance of negative symptoms for this diagnosis. Copyright (C) 2003 S. Karger AG, Basel

Classification of functional psychoses and its implication for prognosis: Comparison between ICD-10 and DSM-IV

Background: The aim was to examine the agreement and differences between ICD-10 and DSM-IV in the classification of functional psychoses. Sampling and Methods: In a sample of 218 first-hospitalised patients, ICD-10 diagnoses were compared with DSM-IV diagnoses. Functional psychoses of both diagnostic systems were classified into the four diagnostic groups schizophrenia, transient/episodic psychoses, delusional disorders and affective disorders. Based on information from a 15-year follow-up, it was examined which course is associated with each diagnostic group. Results: Although in ICD-10 there was a higher frequency of schizophrenia and a lower one of affective disorders, a high agreement between ICD-10 and DSM-IV (kappa value of 0.82) was found. In both diagnostic systems, transient/episodic psychoses and affective disorders were mainly associated with a non-chronic course and schizophrenia was mainly associated with a chronic one. Nevertheless, several patients with transient/episodic psychoses showed a chronic course (ICD-10: 10%, DSM-IV: 15%) and more than one third of patients with schizophrenia a non-chronic one (ICD-10: 40%, DSM-IV: 33%). Conclusions: In the cross-sectional assessment, there is a high diagnostic agreement between ICD-10 and DSM-IV. With respect to the long-term course, the delimitation of transient/episodic psychoses from schizophrenia was neither completely achieved by ICD-10 nor by DSM-IV. Copyright (C) 2004 S. Karger AG, Basel

Finance 1978-79

IPEDS Finance annual report contains the following information: • Revenues by source (e.g., tuition and fees, government, private gifts) • Expenses by function (e.g., instruction, research, plant maintenance and operation) • Scholarships, physical plant assets and indebtedness • Assets, liabilities and net assets • Different formats are used based on the institution’s accounting standard

Mixed Integer Models for the Optimisation of Gas Networks in the Stationary Case

Through out the world the natural gas resources will be one of the most important sources of energy in the future. The development of optimised possibilities for the distribution of gas through a network of pipelines will be very important for an effective operation of a gas transmission network. The aim of this thesis is to formulate this problem as a suitable mathematical mixed integer problem and to find advanced solutions, using techniques of mixed integer programming. The main problem of the so called Transient Technical Optimisation (TTO) is to minimise the total supply costs of a gas transmission company that has to satisfy demands of different kinds. A gas network basically consists of a number of compressors and valves that are connected via pipes. The gas transmission companies dispatchers decide how to run the compressors and how to switch the valves cost-efficiently such that all demands of all customers are satisfied. The cost function mainly consists of the supply costs of driving the compressors. Note that the compressors consum a fraction of the gas transported through the pipelines. The costs imposed by consumed gas should be minimised. The gas transmission network has to satisfy several demands that are described by a minimal or maximal pressure requirement at a certain node or in a pipe. Also the consumers want to get gas of a certain volume and quality. Furthermore some physical constraints, like Kirchhoff's laws have to be modelled. There are also some combinatorial constraints, e.g. the different possibilities of switching the valves or compressor configurations. Note, that some of the constraints are nonlinear, like the pressure loss in a pipeline or the fuel-gas consumption of the compressors. In order to formulate TTO as a mixed integer program we approximate the nonlinear constraints by piecewise linear functions. Considering the experiences of other projects where mixed integer programs have been used, e.g. VLSI-Design or Telecommunications, we know that the problem can be solved by examination of the underlying polyhedra of such complex and high-dimensional mixed integer programs. We know from earlier test evaluations of smaller problems that it is not possible to solve real gas transmission problems with state-of-the-art general mixed integer programming solvers. One programming approach is the search of better valid (or even facet-defining) inequalities of the polyhedra for the use in a Branch-and-Cut Algorithm. We have developed a new class of valid inequalities that have been integrated in a general MIP solver algorithm. Summarising the results it was possible to develop a polynomial separation algorithm for a special class of polyhedra. The use of these cuts reduces the calculation time by a significant factor. A suitable branch-and-bound algorithm is also added. The cuts and the branching algorithms have been tested on several test-models of real gas-networks

ICAM G241A polymorphism and soluble ICAM-1 serum levels: Evidence for an active immune process in schizophrenia

Objectives: We have previously reported reduced serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) in schizophrenic patients. A single-nucleotide polymorphism ( SNP) of the ICAM-1 gene was described at position 241. The G --> A SNP results in a nonsynonymous amino acid exchange of the ICAM-1 protein, and the A allele was shown to be also associated with several immunological disorders like rheumatoid arthritis. Methods: We investigated 70 schizophrenic patients and 128 unrelated healthy control persons regarding the relationship between the serum levels of sICAM-1 and the ICAM-1 G214A polymorphism. Results: We were able to replicate our previous finding of reduced sICAM-1 levels in schizophrenia. Healthy control persons carrying the polymorphic A allele showed markedly lower sICAM-1 serum levels than carriers of the homozygous GG wild type ( p < 0.004). In contrast, no significant difference in the sICAM-1 serum levels were seen regarding the G241A genotype distribution in schizophrenic patients. Conclusion: We hypothesize that the biochemical effect of the G241A SNP is masked in schizophrenic patients, indicating a disease-related mechanism leading to reduced levels of sICAM-1 in schizophrenia. Copyright (C) 2005 S. Karger AG, Basel

Long-term soil accumulation of potentially toxic elements and selected organic pollutants through application of recycled phosphorus fertilizers for organic farming conditions

The pollutant input and the risk of contamination by long-term application of recycled P fertilizers (RPFs) in European agricultural soils were estimated by a mass balance approach. Calculations based on literature data were carried out for the potentially toxic elements (PTEs) Cd, Cr, Cu, Ni, Pb, Zn and for the persistent organic pollutants (POPs) PCBs, PAHs and polychlorinated dibenzo-dioxins and -furans. The PTE accumulation estimation during 200 years of fertilizer application, equivalent to 11 kg P ha-1 year-1, the mean P export via harvested products on European stockless organic farms, regarded soil background concentrations and proposed threshold concentrations. For PTEs, inputs were fertilizer application, atmospheric deposition and liming, output processes were leaching and crop harvest. The effect of varying site conditions was assessed by considering two precipitation excess (F) values and two soil pH values. For POPs, fertilizer application and the half-life time were considered. The PTE accumulation risk was low for most RPFs. For the analysed POPs no accumulation was found. The highest accumulation was found for all PTEs at pH 7 and F = 0.1 m year-1, the lowest at pH 5 and F = 0.3 m year-1. A high P concentration in fertilizers resulted in a low PTE flow per unit of P. composts had the highest PTE accumulation risk due to lowest P contents. Struvite, meat and bone meal, digestate of catering waste, ash and biosolids would be better suited as P fertilizers. The use of fertilizers should be regulated based on their pollutant-to-nutrient ratio

Monetäre Auswirkungen angepassten Reifeninnendrucks im Ackerbau unter besonderer Berücksichtigung der Erbsen

A goal in ecological agriculture is to avoid and reduce soil compaction. One possibility is the use of a tire inflation system (TIS). Additionally, sowing equipment with broader working width can be used. Both technologies save working time and fuel. Furthermore, yield could increase due to less soil compaction, especially for peas as field trials show. Data from the field trials and from original farms were used to calculate the profitability for the soil protection technologies. The fuel savings are enough to cover the variable and fix costs of the TIS. The pea surplus is an extra revenue. If working time reduction is additionally valued than in total the farms can gain above 19,-€/ha arable land using a TIS. The most farms have not enough traction power for broader sowers. If it exists the gain is about 26 €/ha arable land. The gain is mostly enough for the amortization of the TIS. For sowers with broader working width the amortization is only given if there is not a combined cultivation machine or it is at least a cheap one