Job Matching on non-separated Occupational Labour Markets

This work refers to analyses of matching processes on occupational labour markets in Germany. Up to now, all studies in this field are based on the crucial assumption of separate occupational labour markets. I outlined some theoretical considerations that occupational markets are probably not completely separated. By using information about similarities of occupational groups I constructed an 'occupational topology' and finally tested my hypothesis of non-separated occupational labour markets with Spatial Econometric Estimators, particularly with a restricted version of a Spatial Durbin Model that includes “spatial†lags for regressors. The results show considerable dependencies between similar occupational groups in the matching process. Particularly, the results indicate occupational specific set-up and set-down processes in similar occupational groups. This has important implications for estimating the matching efficiencies of unemployed and vacancies, because the matching process is not only determined by the unemployed and vacancies in the same occupational group but also by those in other occupational groups.

City Gate Renovations in Roman Italy, 1st Century B.C.E. - 1st Century C.E.: Exploring the Cultural Conception and Physical Manifestation of the Urban Boundary.

This thesis examines city gates during the first century B.C.E. and first century C.E. It addresses existing literature on city gates and fortifications and how the prevailing interpretation of such structures as primarily military architecture has led to a failure to recognise their important monumental value. It will also explore the lived experiences of Roman cities and interactions with city gates in order to explore their roles as key monuments, and urban artifacts, whose forms and meanings evolved over time. The study will investigate the role of city gates in Roman culture, highlighting the continued religious and cultural importance of the urban boundary in Roman society, and the literary and artistic uses of city gates. This will highlight the contrast between the Roman perception of city gates and their role in modern scholarship on Roman urbanism. The thesis will also offer detailed case studies of city gate renovations at Rome and Pompeii, exploring how the gates’ roles evolved over time and their relationship to the surrounding area. It will consider why, in times of relative peace, these gates were renovated and how their monumental forms and functions reflected the contemporary conception of Roman cities, in order to argue that the city gate was a key marker of the urban boundary; the importance of which persisted throughout this period despite seeming evidence to the contrary

Essays on Matching Processes and Effects of Institutional Changes on Regional and Occupational Labour Markets

The functioning of the labour market and the impact of labour market policies are a long-standing issue in social and political debate. In this respect, labour market research acquires the necessary knowledge and often receives impulses from labour market policy. Conversely, progress in the development of research methods and data mining encourages labour market policymakers to ask new questions that have not been answered yet. The author picks up such developments and focusses on the following three issues: occupational mobility and the job matching efficiency; the development of job matching efficiency on partial occupational markets before, during and after the years of the German labour market reform 2003-2005; the employment effect of the National Minimum Wage in the United Kingdom 1999-2012.Die Fragen, wie der Arbeitsmarkt funktioniert und welchen Einfluss die Politik ausüben kann, sind Dauerbrenner in der gesellschaftlichen und politischen Debatte. Das hierzu nötige Wissen speist sich aus der Arbeitsmarktforschung, die häufig Impulse aus dem Alltagsgeschäft der Arbeitsmarktpolitik bekommt. Umgekehrt laden Fortschritte in der Methodenentwicklung und der Datenerschließung die Arbeitsmarktpolitik dazu ein, neue Fragen aufzuwerfen, die bisher nicht beantwortet werden konnten. Der Autor greift solche Entwicklungen auf und fokussiert drei Themenbereiche: Berufliche Mobilität und Effizienz des Arbeitsmarktausgleichs; die Entwicklung der Effizienz des Arbeitsmarktausgleichs vor, während und nach den Jahren der deutschen Arbeitsmarktreformen 2003-2005 auf beruflichen Teilarbeitsmärkten; die Wirkung des flächendeckenden Mindestlohns in Großbritannien auf die Beschäftigung 1999-2012

Tracking hydrologic response of tile outlet terraces in agricultural systems to storm events

Title outlet terrace (TOT) systems have been employed for the last century as a best management practice (BMP) to control surface runoff and associated erosion in agricultural fields. By altering the topography (artificial subsurface drainage and terraces), the hydrology of the landscape is also altered which affects the transformation, transport, and fate of applied fertilizer (nitrogen and phosphorus compounds) and their effect on other solute behavior. The study of storm events in agricultural fields is useful in identifying mechanisms of nutrient transport and transformation during runoff events under varying antecedent soil moisture conditions (pre-event) and varying growing conditions. Here we aim to track the hydrologic response of agroecosystems to storm events in TOTs to elucidate the relationship between hydrology and fertilizer use on chemical weathering fluxes by: 1) separating runoff into matrix, intermediate, and conduit flow using karst hydrology analytical methods; and, 2) pairing these results with measurements of water chemistry to identify mechanisms of nutrient transport and transformation. We focus on TOT’s with constructed wetlands in the Upper Wakarusa watershed to characterize the water flux of storm events in agricultural fields. Stormwater samples were collected directly from tiles coming off three of these TOT agricultural fields and the receiving wetlands constructed to reduce nutrient runoff. Soil water samples were also collected from nested suction-cup lysimeters that are installed at 30, 60, and 90 cm at the ridge top and depression couplet of one terrace at each field site to quantify spatial variability in nutrient concentrations. All water samples were analyzed for total and dissolved nitrogen and phosphorus, total suspended solids, alkalinity, anions and cations. Storm resolved samples (every 30 mins during flow events) from tile outlets (influent storm water) and wetland outlets (effluent wetland water) were collected using automated water samplers. The digital recursive filter approach was used to separate quickflow and baseflow, as exponential fitting and master recession curves approaches failed to partition hydrographs into their components as the discharge did not behave linearly in log-space. Here the proportion of baseflow increased with the amount of incoming precipitation the week prior to the event. Mixing models derived from measured solutes show that Harvest Hills Middle (HHM, the smallest site) was closest to the atmospheric signature while Cain and Harvest Hills North (HHN) had signatures closer to nested lysimeters. This study suggests that higher tile densities led to lower hydrologic flashiness but greater chemodyanmic behavior, specifically addition behavior, and greater weathering fluxes. This was a surprising result as more chemostatic behavior (i.e., invariant solute concentrations with large variations in discharge) was expected. These results demonstrate that there is likely an interactive effect between tile densities and terraces that may lead to non-linear behavior in solute generation and transport compared to just the effect of tiling alone

An extension to the Navier-Stokes equations to incorporate gas molecular collisions with boundaries

We investigate a model for micro-gas-flows consisting of the Navier-Stokes equations extended to include a description of molecular collisions with solid boundaries, together with first and second order velocity slip boundary conditions. By considering molecular collisions affected by boundaries in gas flows we capture some of the near-wall affects that the conventional Navier-Stokes equations with a linear stress/strain-rate relationship are unable to describe. Our model is expressed through a geometry-dependent mean-free-path yielding a new viscosity expression, which makes the stress/strain-rate constitutive relationship non-linear. Test cases consisting of Couette and Poiseuille flows are solved using these extended Navier-Stokes equations, and we compare the resulting velocity profiles with conventional Navier-Stokes solutions and those from the BGK kinetic model. The Poiseuille mass flow-rate results are compared with results from the BGK-model and experimental data, for various degrees of rarefaction. We assess the range of applicability of our model and show that it can extend the applicability of conventional fluid dynamic techniques into the early continuum-transition regime. We also discuss the limitations of our model due to its various physical assumptions, and we outline ideas for further development

A prediction of cell differentiation and proliferation within a collagen-glycosaminoglycan scaffold subjected to mechanical strain and perfusive fluid flow.

Mesenchymal stem cell (MSC) differentiation can be influenced by biophysical stimuli imparted by the host scaffold. Yet, causal relationships linking scaffold strain magnitudes and inlet fluid velocities to specific cell responses are thus far underdeveloped. This investigation attempted to simulate cell responses in a collagen-glycosaminoglycan (CG) scaffold within a bioreactor. CG scaffold deformation was simulated using micro-computed tomography (CT) and an in-house finite element solver (FEEBE/linear). Similarly, the internal fluid velocities were simulated using the afore-mentioned microCT dataset with a computational fluid dynamics solver (ANSYS/CFX). From the ensuing cell-level mechanics, albeit octahedral shear strain or fluid velocity, the proliferation and differentiation of the representative cells were predicted from deterministic functions. Cell proliferation patterns concurred with previous experiments. MSC differentiation was dependent on the level of CG scaffold strain and the inlet fluid velocity. Furthermore, MSC differentiation patterns indicated that specific combinations of scaffold strains and inlet fluid flows cause phenotype assemblies dominated by single cell types. Further to typical laboratory procedures, this predictive methodology demonstrated loading-specific differentiation lineages and proliferation patterns. It is hoped these results will enhance in-vitro tissue engineering procedures by providing a platform from which the scaffold loading applications can be tailored to suit the desired tissue

Formal search and referrals from a firm's perspective

Rebien M, Stops M, Zaharieva A. Formal search and referrals from a firm's perspective. Center for Mathematical Economics Working Papers. Vol 578. Bielefeld: Center for Mathematical Economics; 2017.This study explores the relationship between firms’ characteristics and their recruitment strategies. We propose a model based on a search and matching framework with two search channels: a formal channel which is costly for firms and a costless informal channel, i.e. referrals. There is a continuum of heterogeneous vacancies in our model where every firm with an open vacancy chooses an optimal search effort in order to attract job candidates. This search effort depends on the productivity of the firm and, contrary to the previous literature, workers send simultaneous applications to open vacancies. We assess the model predictions by using the IAB Job Vacancy Survey, a representative survey among human resource managers in Germany reporting information about their most recent recruitment case. Based on the finding that firm size and productivity are positively correlated we show that: (1) Larger firms invest more effort into formal search activities; (2) Firms invest more formal search effort in labour markets for more educated workers; (3) The positive relationship between firm’s size and formal search intensity can also be observed for firms that don’t use referrals; (4) Firms that use referrals as a search channel invest less effort into formal search compared to firms that don’t use referrals; (5) Larger firms are less likely to hire an applicant by referral than smaller firms, and (6) More intensive search effort leads to a larger number of applications

Zur Einführung von gesetzlichen oder branchenspezifischen Mindestlöhnen: Lohnuntergrenzen und ihre Wirkungen

"Die Anträge der drei Fraktionen Bündnis 90/Die Grünen ('Tarifvertragssysteme stärken – Allgemeinverbindliche Tariflöhne und branchenspezifische Mindestlöhne erleichtern', Bundestagsdrucksache 17/4437), Die Linke ('Tarifsystem stabilisieren', Bundestagsdrucksache 17/8148) und SPD ('Erosion der Tarifvertragssysteme stoppen - Sicherung der Allgemeinverbindlichkeitsregelung von Tarifverträgen', Bundestagsdrucksache 17/8459) zielen darauf ab, das Tarifsystem in Deutschland zu stabilisieren. Durch eine Reform der Allgemeinverbindlicherklärung von Tarifverträgen soll der Ausweitung des Niedriglohnsektors und der Erosion des Tarifvertrags-systems entgegengewirkt werden. Dabei wird besonders die Ausweitung des Arbeitnehmerentsendegesetzes auf alle Branchen und die Einführung eines allgemeinen, gesetzlichen Mindestlohns gefordert. Das IAB äußert sich in dieser Stellungnahme vor allem zur Thematik von gesetzlichen beziehungsweise branchenspezifischen Mindestlöhnen. Zu tarifrechtlichen Fragen nimmt es keine Stellung. Der Vorschlag, das Arbeitnehmerentsendegesetz auf alle Branchen auszuweiten, erscheint nicht zweckmäßig. Ein System, in dem für jede Branche – möglicherweise mit zusätzlichen Differenzierungen nach Qualifikation beziehungsweise Regionen – eine andere Lohnuntergrenze gilt, dürfte aufgrund seiner Komplexität nur äußerst schwer zu administrieren sein. Ein einheitlicher gesetzlicher Mindestlohn hingegen - gegebenenfalls differenziert nach Ost- und Westdeutschland und mit besonderen Regelungen für Jugendliche und junge Erwachsene -, dessen Höhe mit Augenmaß festgesetzt ist, kann das Tarifsystem als untere Grenze stützen und zur Vermeidung von Fehlentwicklungen im Niedriglohnsektor beitragen." (Autorenreferat)"The motions of the three parliamentary groups Bündnis 90/Die Grünen (Alliance 90/The Greens) ('Strengthening collective wage agreement systems – Facilitating generally binding collective wages and branch-specific minimum wages', parliamentary printed document 17/4437), Die Linke (The Left) ('Stabilising the collective wage system', parliamentary printed document 17/8148) and the SPD (Social Democratic Party) ('Stopping the erosion of the collective wage agreement systems – Safeguarding the regulation of the general application of collective wage agreements', parliamentary printed document 17/8459) are aimed at stabilising the collective wage system in Germany. The spread of the low wage sector and the erosion of the collective wage bargaining system are to be counteracted through a reform of the declaration of general application of collective wage agreements. In this the expansion, to all branches, of the law on the posting of workers and the introduction of a general, legal minimum wage are being called for. In this statement, IAB is presenting its research findings concerning the topic of legal and branch-specific minimum wages. It is not commenting on legal issues of wage bargaining. The proposal that the law on the posting of workers should be extended to all branches does not seem feasible. A system in which for each branch – and possibly with separate differentiations according to qualifications and/or regions – a different minimum wage level applies would probably be extremely difficult to administer because of its complexity. A uniform, legal minimum wage on the other hand – possibly differentiated between eastern and western Germany and with special regulations for young people and young adults – whose level has been determined by sound judgement, is capable of supporting the collective wage agreement system as a lower limit and of contributing to avoid things taking a wrong turn within the low wage sector." (author's abstract