Studies in resolution of singularities in positive characteristic

Das Hauptanliegen dieser Dissertation ist es, die auftretenden Phänomene bei der eingebetteten Auflösung von Singularitäten über Körpern mit positiver Charakteristik zu untersuchen. Im ersten Abschnitt wird ein neuer und systematischer Ansatz für die eingebettete Flächenauflösung in positiver Charakteristik entwickelt, welcher derart natürlich ist, dass zumindest die Chance besteht ihn auf höhere Dimensionen verallgemeinern zu können. Dies wird durch die Einführung zweier neuer Invarianten für den induktiven Beweis der Auflösung durch eine Folge von Explosionen bewerkstelligt. Die Invarianten sind systematischer als die bereits bestehenden und ermöglichen eine transparente Argumentation. Dies könnte dazu dienen den noch immer ungelösten Fall der eingebetteten Auflösung von Dreivarietäten in positiver Charakteristik zu untersuchen. Weiters wird die Termination des beschriebenen Algorithmus zur eingebetteten Auflösung von rein inseparablen zwei-dimensionalen Hyperflächen mit Ordnung gleich der Charakteristik durch endlich viele Explosionen bewiesen. Im zweiten Abschnitt werden neue Ideen und Herangehensweisen für die Auflösung von Varietäten mit Dimension größer als zwei, speziell Dreivarietäten, behandelt. Ein Ansatz, der hierzu untersucht wird, ist die Verallgemeinerung der Resultate aus dem ersten Abschnitt auf den Fall von Dreivarietäten. Ferner werden jene Situationen, in denen die klassische Auflösungsinvariante von Charakteristik Null bei Anwendung in positiver Charakteristik fehlschlägt, studiert. Weiters werden neue Invarianten – für Charaketristik Null sowie positive Charakteristik – untersucht. Der letzte Abschnitt befasst sich mit grundlegenden Konstruktionen mittels étaler Umgebungen. Diese werden zum Beispiel verwendet um die Termination des im ersten Abschnitt dargestellten Auflösungsalgorithmus zu zeigen.The main objective of this Ph.D. Thesis is to study the occurring phenomena in embedded resolution of singularities over fields of positive characteristic. In the first part a new and systematic approach to embedded surface resolution in positive characteristic, which is so natural that it has the chance to be generalized to higher dimensions, is given. This is achieved by introducing two new invariants for the inductive proof of the resolution by a sequence of blowups. The invariants are more systematic than the existing ones, and yield a transparent reasoning. This may facilitate to study the still unsolved case of embedded resolution of threefolds in positive characteristic. Moreover the termination of the described algorithm for the embedded resolution of purely inseparable two-dimensional hypersurfaces of order equal to the characteristic in finitely many blowups is proven. In the second part new ideas and attempts for resolution of varieties with dimension larger than two, especially threefolds, are given. One approach that is examined within this thesis is to extend the results from the first part to the case of threefolds. Further, those situations where the classical resolution invariant from characteristic zero increases when used in positive characteristic are studied. Moreover new possible resolution invariants – both for characteristic zero and positive characteristic – are investigated. The last part addresses some basic constructions using étale neighborhoods. They are for instance used to prove the termination of the resolution algorithm presented in the first part

Migrantes haitianos na educação de jovens e adultos no Brasil

Trata-se de uma pesquisa qualitativa que tem por objetivo analisar as intenções e expectativas dos migrantes haitianos na modalidade de Educação de Jovens e Adultos (EJA) no Brasil, município de Cambé, Paraná. Os dados evidenciam que as motivações iniciais dos educandos para ingresso na EJA são: a proficiência da língua portuguesa, ter um diploma internacional e estudar numa escola gratuita. Identificam-se dois perfis desses educandos na EJA: os recém-chegados ao Brasil, que buscam a aprendizagem da língua portuguesa, e os que vivem há mais tempo neste país e aspiram a concluir o ensino médio para ingresso na universidade, objetivando uma ascensão social

Variation in Plasma Corticosterone in Migratory Songbirds: A Test of the Migration-Modulation Hypothesis

Physiological mechanisms underlying migration remain poorly understood, but recent attention has focused on the role of the glucocorticoid hormone corticosterone (CORT) as a key endocrine regulator of migration. The migration-modulation hypothesis (MMH) proposes that baseline plasma CORT levels are elevated in migratory birds to facilitate hyperphagia and lipogenesis and that further elevation of CORT in response to acute stress is suppressed. Consequently, CORT may be a poor indicator of individual condition or environmental variation in migratory birds. We tested the MMH by measuring baseline and stress-induced CORT in common yellowthroats (Geothlypis trichas) during fall migration over 2 consecutive years in the Revelstoke Reach drawdown zone, a migratory stopover site affected by local hydroelectric operations. Birds had low baseline CORT at initial capture (/mL) and then showed a robust stress response, with CORT increasing to ca. 50 ng/mL within 10-20 min. Our data therefore do not support the MMH. Baseline CORT did not vary with body mass, time of capture, Julian day, or year, suggesting that variable flooding regimes did not affect baseline CORT. Individual variation in the rate of increase in CORT was correlated with Julian day, being higher later in the migration period. Our data suggest that plasma CORT can be a useful metric in migration studies

Aldosterone deficiency adversely affects pregnancy outcome in mice

Circulating aldosterone levels are increased in human pregnancy. Inadequately low aldosterone levels as present in preeclampsia, a life-threatening disease for both mother and child, are discussed to be involved in its pathogenesis or severity. Moreover, inactivating polymorphisms in the aldosterone synthase gene have been detected in preeclamptic women. Here, we used aldosterone synthase-deficient (AS−/−) mice to test whether the absence of aldosterone is sufficient to impair pregnancy or even to cause preeclampsia. AS−/− and AS+/+ females were mated with AS+/+ and AS−/− males, respectively, always generating AS+/− offspring. With maternal aldosterone deficiency in AS−/− mice, systolic blood pressure was low before and further reduced during pregnancy with no increase in proteinuria. Yet, AS−/− had smaller litters due to loss of fetuses as indicated by a high number of necrotic placentas with massive lymphocyte infiltrations at gestational day 18. Surviving fetuses and their placentas from AS−/− females were smaller. High-salt diet before and during pregnancy increased systolic blood pressure only before pregnancy in both genotypes and abolished the difference in blood pressure during late pregnancy. Litter size from AS−/− was slightly improved and the differences in placental and fetal weights between AS+/+ and AS−/− mothers disappeared. Overall, an increased placental efficiency was observed in both groups paralleled by a normalization of elevated HIF1α levels in the AS−/− placentas. Our results demonstrate that aldosterone deficiency has profound adverse effects on placental function. High dietary salt intake improved placental function. In this animal model, aldosterone deficiency did not cause preeclampsi

Variation in plasma corticosterone in migratory songbirds: A test of the migration-modulation hypothesis

Physiological mechanisms underlying migration remain poorly understood, but recent attention has focused on the role of the glucocorticoid hormone corticosterone (CORT) as a key endocrine regulator of migration. The migrationmodulation hypothesis (MMH) proposes that baseline plasma CORT levels are elevated in migratory birds to facilitate hyperphagia and lipogenesis and that further elevation of CORT in response to acute stress is suppressed. Consequently, CORT may be a poor indicator of individual condition or environmental variation in migratory birds. We tested the MMH by measuring baseline and stress-induced CORT in common yellowthroats (Geothlypis trichas) during fall migration over 2 consecutive years in the Revelstoke Reach drawdown zone, a migratory stopover site affected by local hydroelectric operations. Birds had low baseline CORT at initial capture (!5 ng/mL) and then showed a robust stress response, with CORT increasing to ca. 50 ng/ mL within 10-20 min. Our data therefore do not support the MMH. Baseline CORT did not vary with body mass, time of capture, Julian day, or year, suggesting that variable flooding regimes did not affect baseline CORT. Individual variation in the rate of increase in CORT was correlated with Julian day, being higher later in the migration period. Our data suggest that plasma CORT can be a useful metric in migration studies

Hippocampal volume in patients with bilateral and unilateral peripheral vestibular dysfunction.

Previous studies have found that peripheral vestibular dysfunction is associated with altered volumes in different brain structures, especially in the hippocampus. However, published evidence is conflicting. Based on previous findings, we compared hippocampal volume, as well as supramarginal, superior temporal, and postcentral gyrus in a sample of 55 patients with different conditions of peripheral vestibular dysfunction (bilateral, chronic unilateral, acute unilateral) to 39 age- and sex-matched healthy controls. In addition, we explored deviations in gray-matter volumes in hippocampal subfields. We also analysed correlations between morphometric data and visuo-spatial performance. Patients with vestibular dysfunction did not differ in total hippocampal volume from healthy controls. However, a reduced volume in the right presubiculum of the hippocampus and the left supramarginal gyrus was observed in patients with chronic and acute unilateral vestibular dysfunction, but not in patients with bilateral vestibular dysfunction. No association of altered volumes with visuo-spatial performance was found. An asymmetric vestibular input due to unilateral vestibular dysfunction might lead to reduced central brain volumes that are involved in vestibular processing

Mountain Wave Propagation under Transient Tropospheric Forcing: A DEEPWAVE Case Study

The impact of transient tropospheric forcing on the deep vertical mountain wave propagation is investigated by a unique combination of in-situ and remote-sensing observations and numerical modeling. The temporal evolution of the upstream low-level wind follows approximately a cos2 shape and was controlled by a migrating trough and connected fronts. Our case study reveals the importance of the time-varying propagation conditions in the upper troposphere, lower stratosphere (UTLS). Upper-tropospheric stability, the wind profile as well as the tropopause strength affected the observed and simulated wave response in the UTLS. Leg-integrated along-track momentum fluxes (−MFtrack) and amplitudes of vertical displacements of air parcels in the UTLS reached up to 130 kN m−1 and 1500 m, respectively. Their maxima were phase-shifted to the maximum low-level forcing by ≈ 8 h. Small-scale waves (λx ≈ 20–30 km) were continuously forced and their flux values depended on wave attenuation by breaking and reflection in the UTLS region

Mountain-Wave Propagation under Transient Tropospheric Forcing: A DEEPWAVE Case Study

The impact of transient tropospheric forcing on the deep vertical mountain-wave propagation is investigated by a unique combination of in situ and remote sensing observations and numerical modeling. The temporal evolution of the upstream low-level wind follows approximately a cos2 shape and was controlled by a migrating trough and connected fronts. Our case study reveals the importance of the time-varying propagation conditions in the upper troposphere and lower stratosphere (UTLS). Upper-tropospheric stability, the wind profile, and the tropopause strength affected the observed and simulated wave response in the UTLS. Leg-integrated along-track momentum fluxes (-MFtrack) and amplitudes of vertical displacements of air parcels in the UTLS reached up to 130 kN m-1 and 1500 m, respectively. Their maxima were phase shifted to the maximum low-level forcing by ≈8 h. Small-scale waves (λx ≈ 20 - 30 km) were continuously forced, and their flux values depended on wave attenuation by breaking and reflection in the UTLS region. Only maximum flow over the envelope of the mountain range favored the excitation of longer waves that propagated deeply into the mesosphere. Their long propagation time caused a retarded enhancement of observed mesospheric gravity wave activity about 12–15 h after their observation in the UTLS. For the UTLS, we further compared observed and simulated MFtrack with fluxes of 2D quasi-steady runs. UTLS momentum fluxes seem to be reproducible by individual quasi-steady 2D runs, except for the flux enhancement during the early decelerating forcing phase