Even though precise evaluation of money demand function is essential for cen- tral banking and for the right determination of the transmission mechanism, economists have not reached a consensus about the underlying determinants of money demand function neither their magnitude and direction. Researchers differ even in the selection of measures used for the main variables - income, and interest rate. While the heterogeneity in elasticity estimates of the former one has been scrutinize in several quantitative surveys, to the best of our knowledge, there has not been compiled any meta-analysis focusing on differences among the interest rate elasticities of the money demand. Therefore, we collected 53 studies reporting 1 094 estimates of interest rate elasticity. Implementing both the state-of-the-art methods and those proposed only recently, we have found out that researches are prone to selective reporting. Firstly, our results shows that negative publication bias is present in empirical studies of the money de- mand and increases the average elasticity estimate approximately three times (in absolute terms). Secondly, negative highly precise estimates are more likely to be compared to their imprecise counterparts. Additionally, we scrutinize po- tential sources of heterogeneity among individual...

[pt] Analisar comportamentos não-competitivos no mercado de trabalho tem se tornado um aspecto crucial para melhorar a compreensão das dinâmicas do mercado de trabalho, e estimar elasticidades-salário da oferta de trabalho pode auxiliar a determinar a existência de estruturas de oligopsônio. Ao construir sobre Manning (2003), uso dados de contratos identificados por empregadorempregado, e aproveito choques específicos de desonerações na folha de pagamento, para estimar elasticidades-salário da oferta de trabalho para o mercado de trabalho brasileiro. Estimamos elasticidades-salário de separações e contratações utilizando de uma abordagem por IV que permite a identificação de variações exógenas nos salários, através da desoneração implementada no Brasil, que representa choques à demanda por trabalho. Enquanto estimativas padrão por MQO são baixas (e irrealistas) como na literatura recente, estimativas usando a abordagem de variáveis instrumentais são muito mais razoáveis. Os resultados indicam a existência de considerável poder de mercado pelo lado de firmas no mercado de trabalho no Brasil, com a elasticidade no nível do mercado de 1.4 e no nível da firma de 4.4. Finalmente, avaliamos se o poder de oligopsônio das firmas difere entre níveis de qualificação, e entre municípios mais ou menos urbanos e informais. Encontramos que as firmas exertem maiores markdowns para trabalhadores menos qualificados, e que maior poder de mercado das firmas está correlacionado com menor urbanização e maior informalidade. / [en] Understanding non-competitive behavior in labor markets has become crucial to gain insight into labor market dynamics, and estimating labor supply wage elasticities can help determine the existence of oligopsony power. By building on Manning (2003), I use matched employer-employee data, and take advantage of sector-specific shocks to payroll taxes, to estimate labor supply wage elasticities for the Brazilian labor market. I estimate separation and recruitment elasticities using an IV approach that allows for the identification of exogenous variation in wages through the reform on payroll taxes implemented in Brazil, which represents shocks to labor demand. While standard OLS estimates are low (and unrealistic) as in the recent literature, estimates using the IV approach are much more reasonable. Results indicate that there exists considerable labor market power by firms in Brazil, with a market-level elasticity of 1.4 and a firm-level elasticity of 4.4. Finally, I evaluate whether oligopsony power is different between skill levels, as well as between more or less urbanized and informal municipalities. I find that firms exert higher markdowns for low-skill workers, and that higher labor market power is correlated with lower urbanization and higher informality.

This paper explores how craft in general, and the tradition of machine knitting in particular, can act as support and an alternative method within healing processes connected to stress and burn-out. The paper uses creative writing and an intimate approach to reach for and highlight metaphors and epiphanies within the making of craft, discussed from micro and macro perspectives. The search for the garden of fiber delights includes discussions and reflections about the artistic practice in relation to thinkers as sociologists Bruno Latour and the actor-network theory, and Hartmut Rosa, and his theory about an accelerating society and the need for resonance. Some of the artists referenced in the paper are Hilma af Klint, Yayoi Kusama and Niki de Saint Phalle. The main wonder of this project and paper is: what will happen when I as an artist start to respond to the seed of resonance within, and not follow the norms and expectations emerged by capitalism causing stress? How can this knowledge be applied in the meeting with other people in need of healing and rest?

Through enrichment of the elastic potential by the second-order gradient of deformation, gradient elasticity formulations are capable of taking nonlocal effects into account. Moreover, geometry-induced singularities, which may appear when using classical elasticity formulations, disappear due to the higher regularity of the solution. In this contribution, a mixed finite element discretization for finite strain gradient elasticity is investigated, in which instead of the displacements, the first-order gradient of the displacements is the solution variable. Thus, the C1 continuity condition of displacement-based finite elements for gradient elasticity is relaxed to C0. Contrary to existing mixed approaches, the proposed approach incorporates a rot-free constraint, through which the displacements are decoupled from the problem. This has the advantage of a reduction of the number of solution variables. Furthermore, the fulfillment of mathematical stability conditions is shown for the corresponding small strain setting. Numerical examples verify convergence in two and three dimensions and reveal a reduced computing cost compared to competitive formulations. Additionally, the gradient elasticity features of avoiding singularities and modeling size effects are demonstrated.

Cold pilgering is a challenging tube forming process in terms of modeling due to the complexity in kinematic of tools, friction condition and material behavior. The process development has mostly been based on simple formulas and costly full-scale tryouts. The aim in this study is to develop validated Finite element models of cold pilgering to increase the understanding of influence of the process parameters on the produced tubes. In the course of this thesis, three-dimensional mechanical and thermo-mechanical Finite element models of cold pilgering were developed. The commercial code MSC.Marc was used in the simulations. General 3D models are needed to be able to capture asymmetric deformation in cold pilgering. It was found that tool deflections together with elastic deformation of roll dies have considerable influence on the rolling force. Furthermore, the strain rate and temperature effects on the response of the material and thereby on the rolling force were evaluated.

Numerous eye diseases are linked to biomechanical dysfunction of the retina. However, the underlying forces are almost impossible to quantify experimentally. Here, we show how biomechanical properties of adult neuronal tissues such as porcine retinae can be investigated under tension in a home-built tissue stretcher composed of nanostructured TiO2 scaffolds coupled to a self-designed force sensor. The employed TiO2 nanotube scaffolds allow for organotypic long-term preservation of adult tissues ex vivo and support strong tissue adhesion without the application of glues, a prerequisite for tissue investigations under tension. In combination with finite element calculations we found that the deformation behavior is highly dependent on the displacement rate which results in Young’s moduli of (760–1270) Pa. Image analysis revealed that the elastic regime is characterized by a reversible shear deformation of retinal layers. For larger deformations, tissue destruction and sliding of retinal layers occurred with an equilibration between slip and stick at the interface of ruptured layers, resulting in a constant force during stretching. Since our study demonstrates how porcine eyes collected from slaughterhouses can be employed for ex vivo experiments, our study also offers new perspectives to investigate tissue biomechanics without excessive animal experiments.

My dissertation consists of three essays on labor supply responses, along the extensive margin (participation into the labor force) and along the intensive margin (intensity of work on the job). The first two essays focus on the labor supply responsiveness of single women with children to taxation and welfare programs. The third essay investigates the effects of marriage, the wage rate, and the associated tax rate on men's labor supply. In the first essay, to avoid bias from the fact that labor supply outcomes are being driven by self-selection, I build a dynamic stochastic discrete choice model to investigate the long run effects of the earned income tax credit and welfare policies on single mothers' labor supply. Simulated method of moments is used to estimate parameters of this dynamic model, based on March CPS data files from 1964 to 2013. I compare the performance of the dynamic stochastic discrete choice model, a static model, and a reduced-form model. My analysis concludes that the dynamic stochastic discrete choice model captures the simultaneous impact of the state variables on the predicted employment decision. My study provides evidence of the long-run positive effect of public policy on low income families in a life-cycle setting. This essay also emphasizes the importance of education in increasing single mothers' labor supply. The second essay is designed to identify factors that help single mothers leave TANF within a short span of time. I find strong evidence for the importance of child support assistance to single mothers' success in exiting TANF with a job. I uncover evidence that work-related activities do not induce TANF participants to leave within a short span of time. My analysis also suggests that health issues significantly limit the ability of single mothers to exit TANF. In the third essay, the main research question is how marital status affects the elasticity of the labor supply of males with respect to wages and taxes, in a life-cycle setting. A dynamic panel data model, which extends the literature on dynamic labor supply, indicates that the elasticity of men's labor supply with respect to wages and taxes is affected by marital status. The empirical results using the Panel Study of Income Dynamics (PSID) data show that men who are continuously married to the same wife have a lower average Frisch elasticity than others. / Ph. D.

Cell migration and invasion is a key driving factor for providing essential cellular functions under physiological conditions or the malignant progression of tumors following downward the metastatic cascade. Although there has been plentiful of molecules identified to support the migration and invasion of cells, the mechanical aspects have not yet been explored in a combined and systematic manner. In addition, the cellular environment has been classically and frequently assumed to be homogeneous for reasons of simplicity. However, motility assays have led to various models for migration covering only some aspects and supporting factors that in some cases also include mechanical factors. Instead of specific models, in this review, a more or less holistic model for cell motility in 3D is envisioned covering all these different aspects with a special emphasis on the mechanical cues from a biophysical perspective. After introducing the mechanical aspects of cell migration and invasion and presenting the heterogeneity of extracellular matrices, the three distinct directions of cell motility focusing on the mechanical aspects are presented. These three different directions are as follows: firstly, the commonly used invasion tests using structural and structure-based mechanical environmental signals; secondly, the mechano-invasion assay, in which cells are studied by mechanical forces to migrate and invade; and thirdly, cell mechanics, including cytoskeletal and nuclear mechanics, to influence cell migration and invasion. Since the interaction between the cell and the microenvironment is bi-directional in these assays, these should be accounted in migration and invasion approaches focusing on the mechanical aspects. Beyond this, there is also the interaction between the cytoskeleton of the cell and its other compartments, such as the cell nucleus. In specific, a three-element approach is presented for addressing the effect of mechanics on cell migration and invasion by including the effect of the mechano-phenotype of the cytoskeleton, nucleus and the cell’s microenvironment into the analysis. In precise terms, the combination of these three research approaches including experimental techniques seems to be promising for revealing bi-directional impacts of mechanical alterations of the cellular microenvironment on cells and internal mechanical fluctuations or changes of cells on the surroundings. Finally, different approaches are discussed and thereby a model for the broad impact of mechanics on cell migration and invasion is evolved.

Cell motility under physiological and pathological conditions including malignant progression of cancer and subsequent metastasis are founded on environmental confinements. During the last two decades, three-dimensional cell migration has been studied mostly by utilizing biomimetic extracellular matrix models. In the majority of these studies, the in vitro collagen scaffolds are usually assumed to be homogenous, as they consist commonly of one specific type of collagen, such as collagen type I, isolated from one species. These collagen matrices should resemble in vivo extracellular matrix scaffolds physiologically, however, mechanical phenotype and functional reliability have been addressed poorly due to certain limitations based on the assumption of homogeneity. How local variations of extracellular matrix structure impact matrix mechanics and cell migration is largely unknown. Here, we hypothesize that local inhomogeneities alter cell movement due to alterations in matrix mechanics, as they frequently occur in in vivo tissue scaffolds and were even changed in diseased tissues. To analyze the effect of structural inhomogeneities on cell migration, we used a mixture of rat tail and bovine dermal collagen type I as well as pure rat and pure bovine collagens at four different concentrations to assess three-dimensional scaffold inhomogeneities. Collagen type I from rat self-assembled to elongated fibrils, whereas bovine collagen tended to build node-shaped inhomogeneous scaffolds. We have shown that the elastic modulus determined with atomic force microscopy in combination with pore size analysis using confocal laser scanning microscopy revealed distinct inhomogeneities within collagen matrices. We hypothesized that elastic modulus and pore size govern cancer cell invasion in three-dimensional collagen matrices. In fact, invasiveness of three breast cancer cell types is altered due to matrix-type and concentration indicating that these two factors are crucial for cellular invasiveness. Our findings revealed that local matrix scaffold inhomogeneity is another crucial parameter to explain differences in cell migration, which not solely depended on pore size and stiffness of the collagen matrices. With these three distinct biophysical parameters, characterizing structure and mechanics of the studied collagen matrices, we were able to explain differences in the invasion behavior of the studied cancer cell lines in dependence of the used collagen model.

Teacher absenteeism is a major concern in many school districts around the country. There have been numerous studies on the topic, but we as educators are still dealing with the problems of teacher absenteeism. To get a good understanding of teacher and administrator perceptions of this problem, a quantitative research approach was used. Quantitative data was gathered using a questionnaire with 28 Likert scale questions. One hundred teachers and three administrators participated in this part of the study. In addition, structured questions were used to interview three teachers and three administrators. Multiple regression analyses were conducted to determine which predictor variables presented in the demographic section of the questionnaire contributed to variation in the various dependent variables, e.g. attendance. All multiple regression analyses were performed at the .05 level of statistical significance. The t-test for attendance indicated that the predictor variable, age, was statistically significant and could be concluded that the older the teacher, the less absenteeism. The t-test for attendance indicated that the predictor variable, degree, was statistically significant and could be concluded that the higher the degree, the less absenteeism. The t-test for operating procedures indicated that the predictor variable, years of experience, was statistically significant and could be concluded that the more experience, the more familiar were teachers with the operating procedures of the school. The t-test for training indicated that the predictor variable, years experience, was statistically significant and could be concluded that the more experience, the more inclined regular teachers were for substitute teacher training. The survey responses revealed many similarities between the teachers and administrators. Teachers and administrators believe there is reduced student achievement taking place when there are substitute teachers in the classroom. Because of this, all teachers and administrators feel the need for extensive professional development for substitute teachers. Teachers and administrators agree that student attendance is affected by substitute teachers in the classrooms. From all points of view, it is strongly believed that operational procedures are greatly affected when several regular teachers are absent at the same time and substitutes are in their classrooms.