1,527 research outputs found
Dirichlet conditions in Poincar\'e-Sobolev inequalities: the sub-homogeneous case
We investigate the dependence of optimal constants in Poincar\'e- Sobolev
inequalities of planar domains on the region where the Dirichlet condition is
imposed. More precisely, we look for the best Dirichlet regions, among closed
and connected sets with prescribed total length (one-dimensional Hausdorff
measure), that make these constants as small as possible. We study their
limiting behaviour, showing, in particular, that Dirichler regions homogenize
inside the domain with comb-shaped structures, periodically distribuited at
different scales and with different orientations. To keep track of these
information we rely on a -convergence result in the class of varifolds.
This also permits applications to reinforcements of anisotropic elastic
membranes. At last, we provide some evidences for a conjecture.Comment: arXiv admin note: text overlap with arXiv:1412.294
Optimal partitioning of an interval and applications to Sturm-Liouville eigenvalues
We study the optimal partitioning of a (possibly unbounded) interval of the
real line into subintervals in order to minimize the maximum of certain
set-functions, under rather general assumptions such as continuity,
monotonicity, and a Radon-Nikodym property. We prove existence and uniqueness
of a solution to this minimax partition problem, showing that the values of the
set-functions on the intervals of any optimal partition must coincide. We also
investigate the asymptotic distribution of the optimal partitions as tends
to infinity. Several examples of set-functions fit in this framework, including
measures, weighted distances and eigenvalues. We recover, in particular, some
classical results of Sturm-Liouville theory: the asymptotic distribution of the
zeros of the eigenfunctions, the asymptotics of the eigenvalues, and the
celebrated Weyl law on the asymptotics of the counting function
The Cauchy Problem for the Vibrating Plate Equation in modulation spaces
The local solvability of the Cauchy problem for the nonlinear vibrating plate
equation is showed in the framework of modulation spaces. In the opposite
direction, it is proved that there is no local wellposedness in Wiener amalgam
spaces even for the solution to the homogeneous vibrating plate equation.Comment: 2 figures, some misprints correcte
Spectral partitions for Sturm-Liouville problems
We look for best partitions of the unit interval that minimize certain
functionals defined in terms of the eigenvalues of Sturm-Liouville problems.
Via \Gamma-convergence theory, we study the asymptotic distribution of the
minimizers as the number of intervals of the partition tends to infinity. Then
we discuss several examples that fit in our framework, such as the sum of
(positive and negative) powers of the eigenvalues and an approximation of the
trace of the heat Sturm-Liouville operator
A Minimaxmax Problem for Improving the Torsional Stability of Rectangular Plates
We use a gap function in order to compare the torsional performances of
different reinforced plates under the action of external forces. Then, we
address a shape optimization problem, whose target is to minimize the torsional
displacements of the plate: this leads us to set up a minimaxmax problem, which
includes a new kind of worst-case optimization. Two kinds of reinforcements are
considered: one aims at strengthening the plate, the other aims at weakening
the action of the external forces. For both of them, we study the existence of
optima within suitable classes of external forces and reinforcements. Our
results are complemented with numerical experiments and with a number of open
problems and conjectures
Essays on Gender Pay Gaps and Wealth Concentration
This dissertation consists of four independent chapters. While the first three chapters investigate different reasons for the Gender Pay Gap, the last chapter is concerned with the top tail of the wealth distribution.
Chapter 1 is concerned with the question why some occupations have large Gender Pay Gaps while others have only small gaps. This chapter aims at uncovering the relationship between occupational characteristics and the Gender Pay Gap. I find that wage differences between men and women are lower in occupations with linear earnings, with a large share of public firms and a low share of persons with supervisory power. Finally, the Gender Pay Gap is lower in occupations with non-routine tasks. Moreover, the findings suggest that the more that employees can be substituted with other employees, the lower is the Gender Pay Gap. Hence, this study extends previous findings on the relationship between the Gender Pay Gap and occupational characteristics on a more general level.
In chapter 2, we analyze whether the Gender Pay Gap within occupational positions comes from different effects on earnings growth for men and women due to promotion. Using administrative data, we are the first to investigate potential gender gaps in earnings increase due to a promotion in Germany and to analyze differences in the gender gap across promotions into different occupational positions. Our results emphasize that women's earnings growth is larger than men's after being promoted to the same position. We find that this effect is mainly due to selection, since we compare a highly positively selected group of women to an average group of men.
In chapter 3 we analyze the impact of the German Parental Leave Reform of 2007 on mothers' long-term earnings. We confirm previous findings and show that the average duration of employment interruptions increases for high-income mothers. This effect, however, translates into a positive effect on earnings for mothers with high prior-to-birth earnings that diminish in the long run. Descriptive evidence suggests that the stronger involvement of fathers, incentivized by the reform, could have facilitated mothers' re-entry to the labor market and thereby increased earnings. For mothers with low prior-to-birth earnings, however, we do not find any beneficial labor market effects of this parental leave reform.
In chapter 4 we analyze the top tail of the wealth distribution in France, Germany and Spain using the Household Finance and Consumption Survey (HFCS). Since top wealth is likely to be underrepresented in household surveys, we integrate big fortunes from rich lists, estimate a Pareto distribution, and impute the missing rich. As a result, the top one percent wealth share increases notably for the three selected countries after imputing the top wealth. We find that national rich lists can improve the estimation of the Pareto coefficient in particular when the list of national USD billionaires is short.Diese Dissertation besteht aus vier unabhängigen Kapiteln. Während sich die ersten drei Kapitel mit unterschiedlichen Gründen für den Gender Pay Gap auseinandersetzen, fokussiert sich das letzte Kapitel auf das obere Ender der Vermögensverteilung.
Kapitel 1 befasst sich mit der Frage, warum einige Berufe große und andere nur geringe Gender Pay Gaps aufweisen und, ob dies mit den Berufsmerkmalen zusammenhängt. Die Ergebnisse zeigen, dass die Lohnunterschiede zwischen Männern und Frauen in Berufen mit linearer Entlohnung, mit einem hohen Anteil an öffentlichen Unternehmen und einem kleinen Anteil von Personen in Führungspositionen geringer sind. Zudem ist das geschlechtsspezifische Lohngefälle in Berufen mit nicht-routinemäßigen Tasks geringer. Die vorliegende Studie erweitert daher den bisherigen Erkenntnisstand, da sie einen allgemeinen Zusammenhang zwischen dem Gender Pay Gap und den Berufsmerkmalen herstellt.
In Kapitel 2 wollen wir die Gründe für die geschlechtsspezifische Lohnlücke innerhalb von beruflicher Positionen verstehen und in diesem Zusammenhang untersuchen, ob berufliche Aufstiege bei Männern und Frauen zu den gleichen Lohnanstiegen führen. Unsere Ergebnisse bestätigen frühere Untersuchungen indem sie zeigen, dass die Lohnanstiege von Frauen nach einem beruflichen Aufstieg innerhalb der gleichen Position größer sind als die von Männern. Die deskriptiven Ergebnisse aber legen nahe, dass dieser Effekt hauptsächlich auf Selektion zurückzuführen ist, da wir eine sehr positiv selektierte Gruppe von Frauen mit einer durchschnittlichen Gruppe von Männern vergleichen.
In Kapitel 3 analysieren wir die Auswirkungen der Elterngeldreform, die 2007 durchgeführt wurde, auf die langfristigen Löhne von Müttern. Mit unseren Ergebnissen bestätigen wir frühere Studien und zeigen, dass die durchschnittliche Dauer der Erwerbsunterbrechungen bei Müttern mit hohem Einkommen zunimmt. Dieser Effekt schlägt sich bei diesen Müttern sogar in höheren Löhnen nieder, die in der langen Frist kleiner werden. Anhand deskriptiver Evidenz gehen wir davon aus, dass die durch die Reform bedingt stärkere Einbindung der Väter, den Wiedereinstieg der Mütter in den Arbeitsmarkt erleichtert und damit deren Löhne erhöht haben könnte. Für Mütter, die vor der Geburt geringe Löhne hatten, finden wir jedoch keine positiven Arbeitsmarkteffekte dieser Elternzeitreform.
In Kapitel 4 analysieren wir das obere Ende der Vermögensverteilung in Frankreich, Deutschland und Spanien. Da das Vermögen der Superreichen in den Haushaltsbefragungen wahrscheinlich unterrepräsentiert ist, kombinieren wir die Survey-Daten zusätzlich mit den Vermögensangaben aus reichen Listen. Infolgedessen steigt der Vermögensanteil des oberen 1 \% für die drei ausgewählten Länder nach der Imputation der Topvermögen deutlich an. Unsere Ergebnisse zeigen, dass die nationalen Reichenlisten die Schätzung des Pareto-Koeffizienten insbesondere dann verbessern können, wenn es nur wenige nationale USD-Milliardäre auf der Forbes-Liste gibt
Settler Colonialism and the Movement Towards Indigenous Forest Sovereignty
This research paper examines the historical and political implications of settler colonialism on Indigenous nations in forested areas around the world. Through a thorough analysis of the Haida First Nation, Pacheedaht First Nation, and the Sámi people, it is argued that settler colonial legislation systematically and intentionally separated Indigenous people and their knowledge from forested areas. Since then, shared management protocols have been implemented to amend racist and environmentally degrading legislation on forested land, but are limited in their effect to reconcile the settler colonial legal system. The only true way to reconcile the settler colonial structure in place that degrades Indigenous nations and their forests is through full Indigenous forest sovereignty
Efeitos do hipotireoidismo no crescimento neuronal, in vitro
TCC(graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Biológicas. Biologia.Astrócitos são células que desempenham funções chave para o funcionamento do sistema nervoso central (SNC), atuando na manutenção da homeostase do microambiente neural, influenciando a migração celular, a captação e liberação de neurotransmissores, a concentração iônica do tecido nervoso e a estabilidade da barreira hematoencefálica. Os astrócitos apresentam ainda atividade de regulação da concentração extracelular de Ãons, além de participarem do metabolismo da glicose e sintetizarem e liberarem diversos fatores neurotróficos. Adicionalmente, os astrócitos são os principais transportadores da tiroxina do sangue e, sendo responsáveis pela sua conversão a T3, fornecem aos tecidos nervosos o hormônio em sua forma ativa. A falta deste hormônio durante o primeiro trimestre de vida pós-natal em humanos resulta em cretinismo, sÃndrome caracterizada por retardo mental severo e, em modelo de rato, promove anormalidades morfológicas irreversÃveis no cérebro. O objetivo desse trabalho foi avaliar os efeitos do hipotireoidismo no crescimento de neurônios, cultivados em regime de co-cultura com astrócitos cerebelares provenientes de animais Wistar neonatos eutireóideos ou hipotireóideos. Observou-se uma visÃvel diminuição no número de neurônios ao serem cultivados sobre astrócitos hipotireóideos, que é ainda mais pronunciada quando os neurônios são hipotireóideos. Na condição de astrócitos eutireóideos, não houve diferença significativa no número de neurônios normais ou hipotireóideos. Nos experimentos de tratamento com T3, o aumento no número de neurônios foi maior nas concentrações de 1 nM e 10 nM de T3, apesar da concentração de 0,5 nM também ter apresentado aumento significativo no crescimento neuronal em relação à condição controle. Quando os neurônios hipotireóideos foram cultivados diretamente sobre poli-ornitina e mantidos com meio condicionado por astrócitos hipotireóideos tratados com T3, o número de neurônios encontrado foi muito inferior ao visto nas condições de culturas anteriores. Apesar disso, todas as células que receberam o meio condicionado por astrócitos que haviam sido tratados com T3 apresentaram crescimento neuronal significativo em relação à condição controle. Estes resultados demonstram que o crescimento neuronal depende diretamente da influência dos astrócitos, tanto pelo contato-célula quanto pela influência da matriz extracelular (MEC) e dos fatores solúveis secretados pelos neurônios, já que podem ser encontrados estudos na literatura que indicam que o microambiente gerado por astrócitos hipotireóideos é mais pobre em MEC e fatores de crescimento que o gerado por astrócitos normais. Portanto, conclui-se que a melhor condição para o desenvolvimento neuronal envolve a secreção de fatores secretados pelos astrócitos em resposta ao hormônio tireoidiano além de contatos célula-célula
- …