Explaining the Joint Behavior of Employment, Unemployment and Nonparticipation

This paper argues that existing matching models with unemployment as an active search and nonparticipation as an inactive search predict counterfactual results: the unemployment rate is at most two times as volatile as the employmentpopulation ratio; only 20 percent of the actual volatility of the unemployment rate is accounted for; and the labor market variables are perfectly correlated with each other. This paper proposes a modified matching model in which workers are classified after matches take place. The modified model generates the direct transition from nonparticipation to employment with no assumption that nonparticipation is an inactive search and without adjusting the time period of the model. The model also explains the important cyclical features of the U.S. labor market.Search and Matching, Business Cycles, Unemployment, Labor Force Participation

Electronic correlations in inhomogeneous model systems: numerical simulation of spectra and transmission

Many fascinating features in condensed matter systems emerge due to the interaction between electrons. Magnetism is such a paramount consequence, which is explained in terms of the exchange interaction of electrons. Another prime example is the metal-to-Mott-insulator transition, where the energy cost of Coulomb repulsion competes against the kinetic energy, the latter favoring delocalization. While systems of correlated electrons are exciting and show remarkable and technologically promising physical properties, they are difficult to treat theoretically. A single-particle description is insufficient; the quantum many-body problem of interacting electrons has to be solved. In the present thesis, we study physical properties of half-metallic ferromagnets which are used in spintronic devices. Half-metals exhibit a metallic spin channel, while the other spin channel is insulating; they are characterized by a high spin polarization. This thesis contributes to the development of numerical methods and applies them to models of half-metallic ferromagnets. Throughout this work, the single-band Hubbard Hamiltonian is considered, and electronic correlations are treated within dynamical mean-field theory. Instead of directly solving the lattice model, the dynamical mean-field theory amounts to solving a local, effective impurity problem that is determined self-consistently. At finite temperatures, this impurity problem is solved employing continuous-time quantum Monte Carlo algorithms formulated in the action formalism. As these algorithms are formulated in imaginary time, an analytic continuation is required to obtain spectral functions. We formulate a version of the N-point Padé algorithm that calculates the location of the poles in a least-squares sense. To directly obtain spectra for real frequencies, we employ Hamiltonian-based tensor network methods at zero temperature. We also summarize the ideas of the density matrix renormalization group algorithm, and of the time evolution using the time-dependent variational principle, employing a diagrammatic notation. Real materials never display perfect translational symmetry. Thus, realistic models require the inclusion of disorder effects. In this work, we discuss these within a single-site approximation, the coherent potential approximation, and combine it with the dynamical mean-field theory, allowing to treat interacting electrons in multicomponent alloys on a local level. We extend this combined scheme to off-diagonal disorder, that is, disorder in the hopping amplitudes, by employing the Blackman–Esterling–Berk formalism. For this purpose, we illustrate the ideas of this formalism using tensor diagrams and provide an efficient implementation. The structure of the effective medium is discussed, and a concentration scaling is proposed that resolves some of its peculiarities. The limit of vanishing hopping between different components is discussed and solved analytically for the Bethe lattice with a general coordination number. We exemplify the combined algorithm for a Bethe lattice, showing results that exhibit alloy-band-insulator to correlated-metal to Mott-insulator transitions. We study models of half-metallic ferromagnets to elucidate the effects of local electronic correlations on the spectral function. To model half-metallicity, a static spin splitting is used to produce the half-metallic density of states. Applying the Padé analytic continuation to the self-energy instead of the Green’s function produces reliable spectral functions agreeing with the zero-temperature results obtained for real frequencies. To address transport properties, we investigate the interface of a half-metallic layer and a metallic, band insulating, or Mott insulating layer. We observe charge reconstruction which induces metallicity at the interface; quasiparticle states are present in the Mott insulating layer even for a large Hubbard interaction. The transmission through a barrier made of such a single interacting half-metallic layer sandwiched by metallic leads is studied employing the Meir–Wingreen formalism. This allows for a transparent calculation of the transmission in the presence of the Hubbard interaction. For a strong coupling of the central layer to the leads, we identify high intensity bound states which do not contribute to the transmission. For small coupling, on the other hand, we find resonant states which enhance the transmission. In particular, we demonstrate that even for a single half-metallic layer, highly polarized transmissions are achievable

Fracture of sandwiched composites

Fracture of a pair of collinear cracks in various materials, such as an isotropic strip, an orthotropic strip, a bonded isotropic adhesive layer, and sandwiched orthotropic layers, is investigated. The crack surfaces are subjected to an arbitrary opening pressure p(x). The problems are formulated in terms of Fredholm integral equation of the second kind by making use the techniques of Fourier transform and finite Hilbert transform. In case of uniform opening pressure p(x) = [sigma], exact expressions for the stress intensity factors and the shape of deformed crack are obtained. Numerical calculations are carried out to study the effects of various boundary geometries and material properties on the fracture of the chosen materials

Midwest China Oral History and Archives Collection

Chang Yau-Weh and Lam Ying China Experience: family background; education; conversion to Christianity and reactions to conversion; memories of Rev. Wu Ming-chieh; response to missionary work on the Mainland; personal work for and description of Lutheran Church in Hong Kong.https://digitalcommons.luthersem.edu/china_histories/1015/thumbnail.jp

Form and function in the hominoid tarsal skeleton.

This thesis explores form variation in the adult tarsal skeleton of extant and fossil hominoids. Three dimensional coordinate data were obtained from five bones of the foot: the calcaneus, talus, cuboid, navicular and medial cuneiform. The comparative sample was made up of Homo sapiens, Pan troglodytes troglodytes, Pan paniscus, Gorilla gorilla gorilla and Pongo pygmaeus. The fossil sample consisted of tarsal remains assigned to a number of Late Pliocene taxa: Australopithecus afarensis, Australopithecus africanus, Paranthropus robustus and Homo habilis. Statistical shape analysis was conducted using geometric morphometric techniques. The first section of analysis explores sexual dimorphism in the extant hominoid foot. It is found that there is no shape dimorphism in the forefoot, and a marginal amount in the hindfoot of Gorilla and Pongo only. Such differences are likely to be linked to high degrees of body mass dimorphism in those taxa. The section concludes that shape dimorphism is unlikely to be an important factor in explaining differences between fossil hominin pedal remains. The second section explores the inter-specific relationship between the tarsals of the extant hominoids. It is found that shape differences between taxa closely mirror those differences already described in the literature. However, it is found that the phenetic relationship between the taxa varies from bone to bone, and, furthermore, does not match the consensus molecular phylogeny. The section concludes that some tarsals are more specialised and remodelled than others, and thus great caution should be taken when considering isolated fossil pedal specimens. The third section incorporates the fossil specimens into the study. It is found that the morphology of the A. africanus and H. habilis tarsals are very similar, and fall within extant hominoid intra-specific ranges of variation. However, the morphology of the A. afarensis tarsals are considerably distinct, and show a different overall pattern to those of A. africanus and H. habilis. The section concludes that all taxa were mosaic in their affinities, but were mosaic in different ways. This thesis concludes that it is likely that there were at least two distinct ways in which the tarsals of different hominin taxa had adapted to bipedal locomotion. This finding supports recent new discoveries suggesting a far wider degree of taxonomic diversity in the African fossil hominin record than had previously been thought

Einfluss verschiedener Anbaustrategien auf Ertrag und Pflanzengesundheit von Zwiebeln (Allium cepa L.)

In field experiments in five Bavarian farms three cultivation systems of onion produc-tion were compared: direct sowing, planting of set onions and planting of seedlings with 7 seeds per each tray. In three of five farms the onions yield up to more than 500 dt ha-1and in average the planted seedling yielded higher than the sown ones. In the other farms, where the set onions where included in the trials, the yields were lower depending on the high and early infection with downy mildew. The plant density (90-70 plant m-2) had more effect on the onion size distribution than on the total yield

Limitierte symbolische Generalisierungen als Merkmal des Spiels: eine Studie zur Unterscheidung rekursiver Erwartungen in Spiel- und Alltagshandlungen

Bisher lassen sich Emergenz und Reiz von Spielphänomenen nicht einheitlich erklären. Auf der Grundlage der Theorie sozialer Systeme werden symbolische Generalisierungen als Kernelemente für psychosozialen Strukturaufbau in dieser Studie zum Ausgangspunkt für die Beobachtung der Differenz von Spiel- und Alltagshandlungen. Es wird untersucht, ob sich Spiel als Zustand konvergenter Erwartungshaltungen definieren lässt. Die These behauptet, dass sowohl zeitliche, sachliche als auch soziale Orientierungen im Spiel als begrenzte Dimensionen antizipiert werden und sich damit von allen anderen kommunikativen Handlungen unterscheiden. Nach der Begründung des Themas wird im ersten Teil die Plausibilität der These durch den soziologischen Konstruktivismus nach Luhmann an den Wirkungen von Spiel - Lernen und Emotionen - begründet und mit natur- und geisteswissenschaftlichen Erkenntnissen verglichen. Im empirischen Teil werden die Entwicklungen zu einem innovativen Studiendesign beschrieben und die Ergebnisse dokumentiert. Aus qualitativen Befragungen zur Wahrnehmung von Sinndimensionen wurden Aussagen konstruiert, mit denen sich im Anschluss eine quantitative Untersuchung durchführen ließ. Der Befund der Studie ergibt zum einen, dass eine Differenzierung von Spiel und Nicht-Spiel entlang der Unterscheidung konvergenter und divergenter Erwartungshaltungen möglich ist und diese deshalb als Untersuchungsobjekt genutzt werden können. Zum anderen zeigte sich, dass die Unterscheidungsfähigkeit von Spielern geleistet werden kann, Nichtspieler jedoch eine hochsignifikante Unsicherheit bei der Zuordnung von Erwartungen aus Spiel und Alltag aufweisen. Zusätzlich zur Bestätigung der These kann durch die Studie angenommen werden, dass Spieler ihre Umwelt differenzierter einschätzen können, als Nicht-Spieler.:Inhalt 1. Einleitung 5 1.1 Anmerkungen zur herangezogenen Literatur 17 2. Begründung des Themas / Problemstellung 19 2.1 System-Umwelt-Verhältnisse 20 2.1.1 Psychophysische Entspannung 20 2.1.2 Psychische Stabilisation 22 2.1.3 Soziale Sicherung 24 2.1.4 Übung, Lernen, Kreativität 25 2.1.5 Schlussfolgerungen 27 2.2 Methodische Überlegungen 28 2.2.1 Zur Wahl des theoretischen Schwerpunktes 29 2.2.2 Begründung der quantitativen Studie 33 3. Zur Theorie symbolischer Generalisierungen 36 3.1 Erwartungen im Kontext der Konstitution von Gesellschaft und Individuum 36 3.2 Interdependenz von Individuum und Gesellschaft 38 3.3 Systemtheoretisches Modell 41 3.3.1 Beobachtung 44 3.3.2 Sinn 45 3.2.2.1 Zeitdimension 46 3.3.2.2 Sachdimension 47 3.3.2.3 Sozialdimension 48 3.3.3 Repräsentationen 50 3.3.4 Funktion der Erwartung 51 3.3.5 Erleben und Handeln 55 3.4 Zusammenfassung 57 4. Lernen 59 4.1 Neurobiologische Voraussetzungen für Gedächtnis und Lernprozesse 61 4.1.1 Neuroplastische Mechanismen 61 4.1.1.1 LTP und LTD 62 4.1.1.2 Gliazellen, gap junctions 63 4.1.2 Schaltkreise und Parallelverarbeitung 64 4.1.2.1 Limbisches System 66 4.1.2.2 Assoziativer Cortex 67 4.1.3 Zusammenfassung 69 4.2 Emotionen und Lernen 70 4.3 Lerndisposition 74 4.3.1 Motivation und Erfahrung 74 4.3.2 Lernen und Zeit 76 4.3.3 Relationen 77 4.4 Lerneffekte durch Spiel 80 4.5 Zusammenfassung 82 4.5.1 Transfer auf Erwartungen 82 5. Emotionen 84 5.1 Bewertung als Funktion der Gefühle 86 5.2 Erwartungsbezogene Konditionierung 89 5.2.1 Hirnorganische Grundlagen 90 5.2.2 Kulturelle Prägung 93 5.3 Zusammenfassung 93 5.3.1 Exkurs: Enttäuschung und Emotion 94 6. Zusammenfassung der theoretischen Ausführungen 96 7. Integration – Spiel als Sonderform von Erwartungshaltung 97 7.1 Wirkung Zeitdimension 98 7.2 Wirkung Sachdimension 99 7.3 Wirkung Sozialdimension 101 7.4 Spiel als Ergebnis einer Beobachtung? 102 7.5 Zusammenfassung: Der Sinn des Spiels 104 8. Thesen 106 9. Empirische Untersuchung 107 9.1 Überlegungen zur Konstruktion der Studie 107 9.2 Einschätzung der Wahrnehmungen von Sinndimensionen- Qualitative Vorstudie 109 9.2.1 Beschreibung der Probanden 110 9.2.2 Durchführung 114 9.2.3 Kategorisierung und Ergebnisse 115 9.2.3.1 Kategorien der Zeitdimension 115 9.2.3.2 Kategorien der Sachdimension 117 9.2.3.3 Kategorien der Sozialdimension 120 9.3 Erläuterungen zur quantitativen Untersuchung 122 9.3.1 Operationalisierung 122 9.3.5 Zur Konstruktion der Untersuchungsaussagen 123 9.3.6 Beschreibung der Indikatoren 126 9.3.6.1 Zeitdimension (Z) = Zunahme – Einschränkung der biografischen Perspektive 126 9.3.6.2 Sachdimension (Y) = Erfolgsaussicht – Versagensrisiko 129 9.3.6.3 Soziadimension (X) = Bestätigung – Ablehnung der Identität 132 9.4 Beurteilung des Messinstruments 135 9.5 Pre-Test und Konsequenzen 137 9.5.1 Zur Unterscheidung von Experimental- und Vergleichsgruppe 139 9.5.2 Vergleich der Einstellung von Spielern und Nichtspielern 140 9.5.3 Gestaltung des Fragebogens 141 9.6 Durchführung 142 10. Auswertung 146 10.1 Ergebnisse 148 10.1.1 Kompletter Datensatz 149 10.1.2. Ergebnisse der Indikatoren und Variablen 152 10.1.2.1 Zeitdimension 152 10.1.2.2 Sachdimension 153 10.1.2.3 Sozialdimension 154 10.1.2.4 Expansive Orientierung 155 10.1.2.5 Restriktive Orientierung 155 10.1.2.6 Subdimensionales Kontrollverhalten 156 10.1.2.7 Altersgruppen 157 10.1.3 Auswertung der Einzelindikatoren 159 10.1.3.1 Zeitdimension 159 10.1.3.2 Sachdimension 161 10.1.3.3 Sozialdimension 163 10.3 Diskussion 166 10.3.1 Interpretation der Einzelergebnisse 166 10.3.2 Befund zur Signifikanz 168 10.2.3 Schlussfolgerungen 169 10.3 Reflexion 172 10.3.1 Ausblick für anschließende Forschung 174 Quellenverzeichnis 177 Anhang 18

Viscous flow and surface crystallization caused by Vickers indentation

Healing and nucleation activity of crack patterns caused by Vickers micro-indentations on the surface of diopside glass (MgO - CaO - 2 SiO2 ) were studied by optical and surface interference microscopy. Minimizing the glass surface during thermal treatments and healing of cracks result in funnel-like depressions symmetrically arranged around the Vickers indentation. Diopside surface crystals predominantly grow from previous crack edges. Thus, double chains of crystals reveal completely healed radial cracks white long range viscous flow at the formation of funnel-like depressions spreads off former double chains to form circular crystal chains