Taxation without Commitment

This paper considers a Ramsey model of linear capital and labor income taxation in which a benevolent government cannot commit ex-ante to a sequence of taxes for the future. In this setup, if the government is allowed to borrow and lend to the consumers, the optimal capital income tax is zero in the long run. This result stands in marked contrast with the recent literature on optimal taxation without commitment, which imposes budget balance and typically finds that the optimal capital income tax does not converge to zero. Since it is efficient to backload incentives, breaking budget balance allows the government to generate surplus that reduces its debt or increases its assets over time until the lack of commitment is no longer binding and the economy is back in the full commitment solution. Therefore, while the lack of commitment does not change the optimal capital tax in the long run, it may impose an upper bound on the level of long run debt.Fiscal Policy; Optimal Taxation; Incidence; Debt

Immigrants’ Entrepreneurial Opportunities: The Case of the Chinese in Portugal

Why do some foreign nationalities seem to have entrepreneurial initiatives and others don’t? Why do certain foreign communities tend to build an ethnic economy, and others melt in the economy of the reception country? The analysis made so far of the modes of incorporation of the different Chinese immigrant communities in Portugal allowed to evidence that, unlike what some authors defend, it is not only the cultural factors that channel immigrants into certain segments of the labour market. Several structural factors associated to these immigrants’ arrival should be considered: the immigration policy of the host society; the reasons that generated the migratory flow; the existence of a co-ethnic community in the country and its economic incorporation; the operation of social networks; the possibility to acquire capital among the community (informal resources); and the potential market of the host society. Furthermore, in Portugal, as in Southern Europe, the informal economy can be an opportunity to self-employment - not so easy in North European countries where institutional control is stronger and competition is higher.Immigrants, Entrepreneurship, Structural opportunities, Ethnic resources

GABAergic transmission impairment promotes the glycinergic phenotype

Tese de mestrado em Bioquímica, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2012A transmissão inibitória desempenha um papel importante na regulação e estabilização da actividade neuronal e é essencial para diversas funções cerebrais como a cognição, percepção, movimento e emoção. As sinapses inibitórias, GABAérgica e glicinérgica, e a sua distribuição, apresentam diferenças no sistema nervoso central dos mamíferos (CNS). A maioria das sinapses inibitórias no cérebro são GABAérgicas, e as glicinérgicas, predominantes na espinal medula e tronco cerebral, tem sido bastante negligenciadas no cérebro. A glicina exerce a sua função através do receptor ionotrópico da glicina (GlyR), um canal pentamérico composto por dois tipos de subunidades (α e β) permeável a iões cloreto e localizado na membrana do terminal pós-sináptico. Os transportadores da glicina 2 (GlyT2) pertencem à família de transportadores dependentes de Na+/Cl-. Estão presentes na membrana dos terminais pré-sinápticos glicinérgicos, assegurando a remoção da glicina da fenda sináptica e permitindo a inserção do neurotransmissor em vesículas sinápticas. O presente estudo tem como principal objectivo investigar quais os principais intervenientes na aquisição do fenótipo glicinérgico. Para isso, efectuou-se uma abordagem farmacológica, em culturas primárias de neurónios, com o propósito de avaliar o fenótipo glicinérgico mediante o comprometimento da transmissão GABAérgica. Os resultados obtidos por western blot e por PCR quantitativo (qPCR) revelaram que a expressão de GlyR e de GlyT2 aumentava significativamente, após tratamento das células com antagonistas do receptor ionotrópico de GABA GABAA (GABAAR) ou do transportador de GABA GAT-1, gabazina e SKF89976a, respectivamente. Em sinaptossomas obtidos de cérebro, a dupla detecção por imunofluorescência, de GlyT2 (marcador de neurónios glicinérgicos) e GAD (marcador de neurónios GABAérgicos) revelou igualmente que, na presença de SKF89976a, a razão entre terminais GABAérgicos e glicinérgicos se apresentava alterada. O comprometimento do sistema GABAérgico resultou no aumento de terminais glicinérgicos puros e mistos, com a consequente diminuição de terminais GABAérgicos. Neste trabalho, a interacção entre o transportador vesicular de aminoácidos inibitórios (VIAAT) e o GlyT2 foi igualmente explorada por ensaios de imunoprecipitação. Os resultados obtidos nesta tese evidenciam, pela primeira vez, que o comprometimento da neurotransmissão GABAérgica induz um aumento dos marcadores da transmissão mediada pela glicina, nomeadamente GlyR e GlyT2, sugerindo assim um mecanismo de compensação entre os dois sistemas inibitórios no cérebro.The inhibitory transmission plays an important role in the regulation and stabilization of brain network activity and is essential for a number of brain functions such as cognition, perception, movement and emotion. GABAergic and glycinergic inhibitory synapses, and their distribution, are very different in the mammalian central nervous system (CNS). Most inhibitory synapses in the brain are GABAergic, and glycinergic ones, predominant in the most caudal regions of the CNS, have been largely disregarded in the brain. Glycine exerts its action through glycine receptors (GlyR), which belong to the superfamily of ligand-gated ion channels, are localized in the postsynaptic membrane and form pentameric channels composed of two different subunits (α and β) permeable to chloride ions. Glycine transporters 2 (GlyT2) belong to the family of Na+/Cl--dependent transporter proteins. They are located in the membrane of glycinergic neurons and are responsible for terminating glycine-mediated neurotransmission by uptaking glycine into glycinergic nerve terminals, allowing for neurotransmitter reloading of synaptic vesicles. The present study aims to investigate which are the principal mediators for the acquisition of a glycinergic phenotype. A pharmacological approach, in primary neuronal cultures, was pursued in order to evaluate the glycinergic phenotype upon a GABAergic transmission impairment. Western blot analysis and quantitative real-time PCR (qPCR) revealed that GlyR and GlyT2 expression increased significantly after treating the cultures with blockers for either GABAA receptor or GABA transporter GAT-1, gabazine and SKF89976a, respectively. In brain synaptosomes, double immunofluorescence of GlyT2 (marker of glycinergic neurons) and GAD (marker of GABAergic neurons) also revealed that, in the presence of SKF89976a, the ratio of GABAergic vs glycinergic terminals changed. GABAergic impairment caused an increase in mixed (GABA and glycine-containing) and pure glycinergic terminals, with a concomitant decrease in GABA-containing boutons. Furthermore, a physical interaction was assessed between Vesicular Inhibitory Amino Acid Transporter (VIAAT) and GlyT2 by immunoprecipitation assays. These results obtained in this thesis have elucidated, for the first time, that impairment in GABA-mediated neurotransmission induces an increase in glycine- mediated transmission components, namely GlyR and GlyT2, and suggest a compensatory mechanism between the two inhibitory systems in the brain

El sud tranquil: el cas de Portugal

A Portugal només un de cada vint-i-cinc habitants és estranger. Polítiques força estrictes i centralitzades han marcat l’estabilitat del país. Destaca una marcada voluntat d’integrar als immigrants

Floods in southern Portugal: their physical and human causes, impacts and human response

Floods have been the most deadly natural disasters in Portugal during the last century, followed by earthquakes. The type of flood known as a ‘progressive flood’ mainly affects the larger basins, such as that of the Tagus River, and results in a large inundated area. These floods are caused by heavy rains associated with a westerly zonal circulation that may persist for weeks. The system of dams within the basin reduces the frequency of flooding, but cannot ‘tame’ the river. The dam system has even contributed to an increase in the peak flow, as in the 1979 flood. Nevertheless, these floods are not a danger for the human population. In contrast, flash floods are more dangerous and deadlier than progressive floods, as demonstrated in 1967 and 1997. They affect the small drainage basins and are caused by heavy and concentrated rainfall, created by convective depressions (active cold pools or depressions caused by the interaction between polar and tropical air masses), active in the south of the country, in the Lisbon region, Alentejo and the Algarve. Deforestation, soil impermeability, chaotic urbanization, building on floodplains, the blockage of small creeks or their canalisation, and the building of walls and transverse embankments along the small creeks all contribute to the aggravation of this kind of flood.info:eu-repo/semantics/publishedVersio

Chinese Entrepreneurship in Portugal: the traditional ethnic strategies?

Although immigrant entrepreneurial activities have always been present in Europe three historical circumstances rendered them more visible in recent decades The increase in immigration flows and the concentration of immigrants in urban contexts stimulated the creation of a different type of demand associated with immigrant communities Also the economic growth and expansion of several markets during the 1950s and 1960s produced a decline in native small and medium enterprises leaving opportunities for immigrants in certain traditional sectors Finally the oil crisis in 1973 74 had substantial impacts in terms of the increase in immigrant unemployment Within this framework immigrants found in entrepreneurship an alternative to economic integration in European societies They were therefore responsible for the increase in rates of entrepreneurship between 1970 and 1980 Light and Rosenstein 1995 12-13 Waldinger et al 1990 8