On dominant contractions and a generalization of the zero-two law

Zaharopol proved the following result: let T,S:L^1(X,{\cf},\m)\to L^1(X,{\cf},\m) be two positive contractions such that $T\leq S$. If $\|S-T\|<1$ then $\|S^n-T^n\|<1$ for all n\in\bn. In the present paper we generalize this result to multi-parameter contractions acting on $L^1$. As an application of that result we prove a generalization of the "zero-two" law.Comment: 10 page

Foreign capital and gender differences in promotions: Evidence from large Brazilian manufacturing firms

This paper examines whether there exists obstacles hindering women's ascension in the largest firms of the Brazilian manufacturing industry. In particular, we check whether gender matters in the time it takes to get a promotion to a managerial position. Once we control for covariate-dependent censoring, we find significant evidence that foreign-owned firms feature less gender differences in promotions than domestic firms. The same applies in other dimensions of career progress, namely, wage growth and promotion likelihood. It turns out that wage gains after promotion contribute to generating wage differential between males and females only within domestic firms. This is consistent with statistical discrimination and with the self-selection that results from employees optimally choosing which jobs to apply for. Jobs in domestic firms offer more flexibility in terms of hours per week, whereas multinationals compete for the most career-concerned workers

EMBEDDED MATRICES FOR FINITE MARKOV CHAINS

For an arbitrary subset A of the finite state space 5 of a Markov chain the so–called embedded matrix PA is introduced. By use of these matrices formulas expressing all kinds of probabilities can be written down almost automatically, and calculated very easily on a computer. Also derivations can be given very systematically

Extracellular alpha-synuclein: Sensors, receptors, and responses

Synucleinopathies are a group of progressive neurodegenerative diseases known for the accumulation of insoluble aggregates containing the protein alpha-synuclein (aSyn). Recently, it has been assumed that pathology spreads in the brain during disease progression, implying that, at some point in the process, aSyn may exist outside of cells. In this context, extracellular-aSyn (e-aSyn) might transduce signals to the inside of the cells it interacts with, and/or be internalized by different types of cells through the extracellular matrix. Both negatively charged lipids and membrane receptors have been hypothesized as modulators of the loss of cellular homeostasis and cytotoxicity, and of the internalization of e-aSyn. Internalized e-aSyn causes the disruption of multiple cellular processes such as the autophagy lysosomal pathway (ALP), mitochondrial function, endoplasmic reticulum (ER)-stress, UPR activation, or vesicular transport. These processes happen not only in neurons but also in glial cells, activating inflammatory or anti-inflammatory pathways that can affect both neuronal function and survival, thereby affecting disease progression. In this review, we explore possible effects e-aSyn, all the way from the extracellular matrix to the nucleus. In particular, we highlight the glial-neuronal relationship as this is particularly relevant in the context of the spreading of aSyn pathology in synucleinopathies

An Introduction to Hyperbolic Barycentric Coordinates and their Applications

Barycentric coordinates are commonly used in Euclidean geometry. The adaptation of barycentric coordinates for use in hyperbolic geometry gives rise to hyperbolic barycentric coordinates, known as gyrobarycentric coordinates. The aim of this article is to present the road from Einstein's velocity addition law of relativistically admissible velocities to hyperbolic barycentric coordinates along with applications.Comment: 66 pages, 3 figure

Gyrations: The Missing Link Between Classical Mechanics with its Underlying Euclidean Geometry and Relativistic Mechanics with its Underlying Hyperbolic Geometry

Being neither commutative nor associative, Einstein velocity addition of relativistically admissible velocities gives rise to gyrations. Gyrations, in turn, measure the extent to which Einstein addition deviates from commutativity and from associativity. Gyrations are geometric automorphisms abstracted from the relativistic mechanical effect known as Thomas precession

Decisões críticas em idades críticas: a escolha dos jovens entre estudo e trabalho no Brasil e em outros paises da America Latina

In this paper we pretend to compare the determinants of the time allocation ofthe teenagers among four Latin American countries: Brazil, Chile, Peru and Honduras. We assume there are four possibilities to time allocation: only studying, only working, doing both ofthem or doing none of them. We focused our attention in Brazil, reporting how far one can extend the conclusions and policy recommendations to the another countries with different social and geographical characteristics. Separate analysis were done for men and women. The specific impacts of each variable on the time allocation of the teenagers were compared through a graphic analysis. The parents education revealed being the most important determinant of the young people's choice in almost all countries and genders analyzed, in the sense that the more educated the parents are, the more likely to study and the less willing to work the children are. In Brazil, for example, sons/daughters of eight-year educated parents have probability of studying 17/14 percentage points lower than sons/daughters of analphabets. Other important variables were the household location and the family composition, however the direction of these impacts depended on the gender and the country considered. This fact supports the argument that institutional/cultural differences have a central role on the teenagers' time allocation

Hydration and packing are crucial to amyloidogenesis as revealed by pressure studies on transthyretin variants that either protect or worsen amyloid disease

The formation of amyloid aggregates is the hallmark of the amyloidogenic diseases. Transthyretin (TTR) is involved in senile systemic amyloidosis (wild-type protein) and familial amyloidotic polyneuropathy (point mutants). Through the use of high hydrostatic pressure (HHP), we compare the stability among wild-type (wt) TTR, two disease-associated mutations (V30M and L55P) and a trans-suppressor mutation (T119M). Our data show that the amyloidogenic conformation, easily populated in the disease-associated mutant L55P, can be induced by a cycle of compression-decompression with the wt protein rendering the latter highly amyloidogenic. After decompression, the recovered wt structure has weaker subunit interactions (loosened tetramer, T(4)(*)) and presents a stability similar to L55P, suggesting that HHP induces a defective fold in the wt protein, converting it to an altered conformation already present in the aggressive mutant, L55P. On the other hand, glucose, a chemical chaperone, can mimic the trans-suppression mutation by stabilizing the native state and by decreasing the amyloidogenic potential of the wt TTR at pH 5.0. The sequence of pressure stability observed was: L55P<V30M<wt<<T119M. The pressure dissociation of L55P at 1 degrees C exhibited dependence on protein concentration, allowing us to assess the volume change of association and the free-energy change. After a cycle of compression-decompression at 37 degrees C and pH 5.6 or lower, all amyloidogenic variants underwent aggregation. Binding of bis-(8-anilinonaphthalene-1-sulfonate) (bis-ANS) revealed that the species formed under pressure retained part of its tertiary contacts (except T119M). However, at neutral pH, where aggregation did not take place after decompression, bis-ANS binding was absent. Thus, TTR has to experience this partially folded conformation to undergo aggregation after decompression. Overall, our studies provide evidence that amyloidogenesis correlates with less packed structures (larger volume changes) and high susceptibility to water infiltration. The hydration effects can be counteracted by osmolytes or by a specific mutation

Ligand Binding and Hydration in Protein Misfolding: Insights from Studies of Prion and p53 Tumor Suppressor Proteins†

Protein misfolding has been implicated in a large number of diseases termed protein- folding disorders (PFDs), which include Alzheimer’s disease, Parkinson’s disease, transmissible spongiform encephalopathies, familial amyloid polyneuropathy, Huntington’s disease, and type II diabetes. In these diseases, large quantities of incorrectly folded proteins undergo aggregation, destroying brain cells and other tissues