Mesomorphic behaviour in copoly(ester-imide)s of poly(butylene-2,6-naphthalate) (PBN)

Copolycondensation of N,N’-bis(4-hydroxybutyl)-biphenyl-3,4,3',4'-tetracarboxylic diimide at 20 and 25 mol% with bis(4-hydroxybutyl)-2,6-naphthalate produces PBN-based copoly(ester-imide)s that not only crystallise but also form a (smectic) mesophase upon cooling from the melt. Incorporation of 25 mol% imide in PBN causes the glass transition temperature (measured by DSC) to rise from 51 to 74 °C, a significant increase relative to PBN. Furthermore, increased storage- (G'), loss- (G'') and elastic (E) moduli are observed for both copoly(ester-imide)s when compared to PBN itself. Structural analysis of the 20 mol% copolymer by X-ray powder and fibre diffraction, interfaced to computational modelling, suggests a crystal structure related to that of α-PBN, in space group P-1, with cell dimensions a = 4.74, b = 6.38, c = 14.45 Å, α = 106.1, β = 122.1, γ = 97.3°, ρ = 1.37 g cm-3.

Fly by data link: feasibility of a relative navigation solution for aviation relying on a future L-band data link

Trabalho final de Mestrado para obtenção do grau de Mestre em Engenharia de Electrónica e Telecomunicações

Packet backbone design differences between commercial network and Container Trial System of LTE/SAE

The mobile networks of earlier and current generations, or 2G and 3G networks, provide users voice and packet services with higher transmission rates and good quality over the same core network. When developing the next generation of mobile networks the current quality of services needs to be maintained. This thesis concentrates on the next generation mobile network, especially on the evolution of the packet network part. The new mobile network has requirements for the common packet backbone network, Mobile Packet Backbone Network, which is additionally discussed in this study. The next generation mobile network, called LTE/SAE, is currently under testing. The test system is called Container Trial System. It is a mini sized LTE/SAE site. The LTE/SAE is studied in this thesis concentrating on the evolved packet core, the SAE part of the composition. The empirical part of the study compares the LTE/SAE Container Trial System and commercial network designs and additionally produces documentation for internal personnel and customers. The research is performed by comparing the documentations and specifications of both the Container Trial System and commercial network. Since the LTE commercial network is not yet constructed, the comparison is done theoretically. The purpose is furthermore to find out if there are any design issues that could be done differently in the next version of the Container Trial System.

Análisis de la influencia de los organismos adscritos a la organización de naciones unidas (UNICEF- ECPAT) en la solución de la problemática de la trata de niños en el sudeste asiático continental. periodo 2000-2010

La trata de niños es un fenómeno cada vez más relevante en el sistema internacional y ha generado importantes esfuerzos de cooperación de agencias internacionales como UNICEF y ECPAT. En ese sentido, ambos organismos han enfocado su actividad en las regiones donde se han registrado los mayores índices de violación de los Derechos Humanos. Este Estudio de Caso se ha centrado en el Sudeste Asiático continental conformado por Tailandia, Laos, Camboya, Vietnam, Singapur, Myanmar y Malasia; con el fin de determinar de qué manera han trabajado ambos organismos en la región y de qué forma han contribuido a la solución de esta problemática por medio de la firma de acuerdos internacionales, implementación de legislación nacional y programas de cooperación. A pesar del trabajo realizado no solo por entidades internacionales sino también por autoridades gubernamentales, no se ha observado una disminución real de las cifras.

Efectos de la crisis económica europea en el panorama migratorio colombiano. Estudio de caso: migración laboral española en Colombia (2008-2013)

Actualmente, Colombia se encuentra inserta en dinámicas migratorias internacionales, no sólo como país expulsor de estos flujos, sino como destino y país de tránsito; la transformación que ha tenido el panorama migratorio colombiano es reciente y obedece a múltiples factores de carácter interno y externo. El fortalecimiento de la economía colombiana y la coyuntura de la crisis económica española han creado un ambiente propicio para la llegada de una migración laboral altamente calificada proveniente de España. Esta situación no sólo ha configurado al país por primera vez como un destino migratorio, sino ha puesto en evidencia la necesidad de una política migratoria eficaz y capaz de enfrentar los desafíos que impone la nueva realidad migratoria.

Motivação e adesão ao exercício físico : um estudo sobre o papel dos treinadores pessoais

Introdução: Procuramos analisar a associação entre a frequência/adesão ao exercício físico (FAEF) em contexto de ginásios e health clubs (GHC) e os constructos previstos pela Teoria da Auto Determinação (TAD) em indivíduos que treinam com Treinador Pessoal (TP)e indivíduos que não treinam com TP. Método: Efetuámos uma revisão sistemática da literatura (RSL), seguida de um estudo observacional onde aplicámos questionários psicométricos para avaliar o clima da sessão de treino, resposta psicológica global, regulação motivacional, satisfação das necessidades psicológicas (NPB), escolha percebida sobre o desempenho em exercício. Foi controlada a FAEF durante 3 meses. A amostra consistiu em 88 clientes (Midade = 41.35, SD = 12.22, MIMC = 25.10, SD = 14.52) Resultados: Na RSL encontrámos 10 estudos, nenhum em contexto de TP. No nosso estudo não se registaram diferenças na FAEF, nem nas regulações motivacionais entre os grupos. No grupo com TP a competência associou-se à FAEF (p=.017) e a autonomia associou-se a menores níveis de mau estar psicológico e de fadiga (p=.032). O Clima de Tratamento do Programa não influenciou nenhum dos outcomes estudados. No grupo sem TP, quanto mais Autonomia (p=.038) e Motivação Intrínseca (p=.001) maior a FAEF. Regulações mais autodeterminadas estão associados a maiores valores de FAEF (p=.009). A motivação intrínseca associou-se positivamente (p=.014) com a FAEF em toda a amostra. Discussão: O suporte das NBP origina uma motivação mais auto regulada o que se reflete numa maior FAEF e bem estar psicológico. No grupo com TP a competência teve um maior contributo para a FAEF, no grupo sem TP a autonomia registou o valor mais elevado. Não se observaram diferenças entre os grupos na regulação motivacional e na FAEF. O suporte de autonomia dado pelo TP não apresentou resultados significativos na FAEF, o que contraria o esperado pela TAD. Estes dados são, por si só reveladores da importância de se aprofundar conhecimentos que auxiliem os TP’s a a motivarem com mais qualidade os seus alunos.

Electron spin resonance study of puff-resolved free radical formation in mainstream cigarette smoke

Puff-by-puff resolved gas phase free radicals were measured in mainstream smoke from Kentucky 2R4F reference cigarettes using ESR spectroscopy. Three spin-trapping reagents were evaluated: PBN, DMPO and DEPMPO. Two procedures were used to collect gas phase smoke on a puff-resolved basis: i) the accumulative mode, in which all the gas phase smoke up to a particular puff was bubbled into the trap (i.e., the 5th puff corresponded to the total smoke from the 1st to 5th puffs). In this case, after a specified puff, an aliquot of the spin trap was taken and analysed; or, ii) the individual mode, in which the spin trap was analysed and then replaced after each puff. Spin concentrations were determined by double-integration of the first derivative of the ESR signal. This was compared with the integrals of known standards using the TEMPO free radical. The radicals trapped with PBN were mainly carbon-centred, whilst the oxygen-centred radicals were identified with DMPO and DEPMPO. With each spin trap, the puff-resolved radical concentrations showed a characteristic pattern as a function of the puff number. Based on the spin concentrations, the DMPO and DEPMPO spin traps showed better trapping efficiencies than PBN. The implication for gas phase free radical analysis is that a range of different spin traps should be used to probe complex free radical reactions in cigarette smoke.

Electron paramagnetic resonance investigation of the free radicals in the gas and particulate phases of cigarette smoke using spin-trapping techniques

Free radicals in cigarette smoke have been studied using spin trapping EPR techniques. 2R4F reference cigarettes were smoked using 35 ml puff volumes of 2 seconds duration, once every 60 seconds. The particulate phase of the smoke was separated from the gas phase by passing the smoke through a Cambridge filter pad. For both phases, free radicals were measured and identified. A range of spin-traps was employed: PBN, DMPO, DEPMPO, and DPPH-PBN. In the gas-phase, short-lived carbon- and oxygen- centered radicals were identified; the ratios between them changed during the smoking runs. For the first puffs, C-centered radicals predominated while for the later puffs, O-centered radicals were mainly observed. The particulate phase and the ‘tar’ were studied as well.

High performance polyester-based materials

Biaxially oriented films produced from semi-crystalline, semi-aromatic polyesters are utilised extensively as components within various applications, including the specialist packaging, flexible electronic and photovoltaic markets. However, the thermal performance of such polyesters, specifically poly(ethylene terephthalate) (PET) and poly(ethylene-2,6-naphthalate) (PEN), is inadequate for several applications that require greater dimensional stability at higher operating temperatures. The work described in this project is therefore primarily focussed upon the copolymerisation of rigid comonomers with PET and PEN, in order to produce novel polyester-based materials that exhibit superior thermomechanical performance, with retention of crystallinity, to achieve biaxial orientation. Rigid biphenyldiimide comonomers were readily incorporated into PEN and poly(butylene-2,6-naphthalate) (PBN) via a melt-polycondensation route. For each copoly(ester-imide) series, retention of semi-crystalline behaviour is observed throughout entire copolymer composition ratios. This phenomenon may be rationalised by cocrystallisation between isomorphic biphenyldiimide and naphthalenedicarboxylate residues, which enables statistically random copolymers to melt-crystallise despite high proportions of imide sub-units being present. In terms of thermal performance, the glass transition temperature, Tg, linearly increases with imide comonomer content for both series. This facilitated the production of several high performance PEN-based biaxially oriented films, which displayed analogous drawing, barrier and optical properties to PEN. Selected PBN copoly(ester-imide)s also possess the ability to either melt-crystallise, or form a mesophase from the isotropic state depending on the applied cooling rate. An equivalent synthetic approach based upon isomorphic comonomer crystallisation was subsequently applied to PET by copolymerisation with rigid diimide and Kevlar®-type amide comonomers, to afford several novel high performance PET-based copoly(ester-imide)s and copoly(ester-amide)s that all exhibited increased Tgs. Retention of crystallinity was achieved in these copolymers by either melt-crystallisation or thermal annealing. The initial production of a semi-crystalline, PET-based biaxially oriented film with a Tg in excess of 100 °C was successful, and this material has obvious scope for further industrial scale-up and process development.

Water deprivation-induced sodium appetite and differential expression of encephalic c-Fos immunoreactivity in the spontaneously hypertensive rat

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Envolvimento da neurotransmissão glutamatérgica da porção dorsolateral da ponte no controle cardiorrespiratório

Em condições de hipóxia (redução da pressão parcial de oxigênio), respostas reflexas de aumento da ventilação pulmonar, aumento da pressão arterial e diminuição da frequência cardíaca são observadas com o objetivo de aumentar os processos de trocas gasosas e perfusão tecidual. Para que essas respostas reflexas à hipóxia ocorram, quimiorreceptores periféricos são ativados pela redução da pressão parcial de oxigênio arterial e enviam sinais excitatórios para o sistema nervoso central, promovendo a excitação de importantes núcleos cerebrais envolvidos com o controle das atividades respiratória, simpática e parassimpática. Evidências experimentais sugerem que os neurônios do complexo parabraquial/Kölliker-Fuse (PBN/KF), importante região respiratória localizada na porção dorsolateral da ponte, contribuem para o processamento das respostas cardiorrespiratórias do quimiorreflexo. Contudo, os neurotransmissores envolvidos ainda não foram explorados. No presente projeto, exploraremos a hipótese de que a neurotransmissão glutamatérgica da região PBN/KF é importante para a manutenção da ventilação basal e para o processamento das respostas ventilatórias à hipóxia. Para tanto, utilizamos a técnica de microinjeção de agonistas e antagonistas dos receptores de L-glutamato no PBN/KF de animais anestesiados e não anestesiados, avaliando parâmetros ventilatórios (eletromiografia dos músculos diafragma e abdominal em animais anestesiados; e frequência respiratória, volume corrente e ventilação minuto em animais não anestesiados) e parâmetros cardiovasculares (pressão arterial e frequência cardíaca em ambas condições experimentais) em condições de repouso ou em situações de estimulação dos quimiorreceptores periféricos (com cianeto de potássio). Nossos dados mostram que nos animais anestesiados houve uma redução...

Envolvimento da neurotransmissão glutamatérgica da porção dorsolateral da ponte no controle cardiorrespiratório

Em condições de hipóxia (redução da pressão parcial de oxigênio), respostas reflexas de aumento da ventilação pulmonar, aumento da pressão arterial e diminuição da frequência cardíaca são observadas com o objetivo de aumentar os processos de trocas gasosas e perfusão tecidual. Para que essas respostas reflexas à hipóxia ocorram, quimiorreceptores periféricos são ativados pela redução da pressão parcial de oxigênio arterial e enviam sinais excitatórios para o sistema nervoso central, promovendo a excitação de importantes núcleos cerebrais envolvidos com o controle das atividades respiratória, simpática e parassimpática. Evidências experimentais sugerem que os neurônios do complexo parabraquial/Kölliker-Fuse (PBN/KF), importante região respiratória localizada na porção dorsolateral da ponte, contribuem para o processamento das respostas cardiorrespiratórias do quimiorreflexo. Contudo, os neurotransmissores envolvidos ainda não foram explorados. No presente projeto, exploraremos a hipótese de que a neurotransmissão glutamatérgica da região PBN/KF é importante para a manutenção da ventilação basal e para o processamento das respostas ventilatórias à hipóxia. Para tanto, utilizamos a técnica de microinjeção de agonistas e antagonistas dos receptores de L-glutamato no PBN/KF de animais anestesiados e não anestesiados, avaliando parâmetros ventilatórios (eletromiografia dos músculos diafragma e abdominal em animais anestesiados; e frequência respiratória, volume corrente e ventilação minuto em animais não anestesiados) e parâmetros cardiovasculares (pressão arterial e frequência cardíaca em ambas condições experimentais) em condições de repouso ou em situações de estimulação dos quimiorreceptores periféricos (com cianeto de potássio). Nossos dados mostram que nos animais anestesiados houve uma redução...

Genetic and pharmacologic manipulation of oxidative stress after neonatal hypoxia-ischemia

Oxidative stress is a critical component of the injury response to hypoxia-ischemia (HI) in the neonatal brain, and this response is unique and at times paradoxical to that seen in the mature brain. Previously, we showed that copper-zinc superoxide-dismutase (SOD1) over-expression is not beneficial to the neonatal mouse brain with HI injury, unlike the adult brain with ischemic injury. However, glutathione peroxidase 1 (GPx1) over-expression is protective to the neonatal mouse brain with HI injury. To further test the hypothesis that an adequate supply of GPx is critical to protection from HI injury, we crossed SOD1 over-expressing mice (hSOD-tg) with GPx1 over-expressing mice (hGPx-tg). Resulting litters contained wild-type (wt), hGPx-tg, hSOD-tg and hybrid hGPx-tg/hSOD-tg pups, which were subjected to HI at P7. Confirming previous results, the hGPx-tg mice had reduced injury compared to both Wt and hSOD-tg littermates. Neonatal mice over-expressing both GPx1 and SOD1 also had less injury compared to wt or hSOD-tg alone. A result of oxidative stress after neonatal HI is a decrease in the concentration of reduced (i.e. antioxidant-active) glutathione (GSH). In this study, we tested the effect of systemic administration of alpha-lipoic acid on levels of GSH in the cortex after HI. Although GSH levels were restored by 24h after HI, injury was not reduced compared to vehicle-treated mice. We also tested two other pharmacological approaches to reducing oxidative stress in hSOD-tg and wild-type littermates. Both the specific inhibitor of neuronal nitric oxide synthase, 7-nitroindazole (7NI), and the spin-trapping agent alpha-phenyl-tert-butyl-nitrone (PBN) did not reduce HI injury, however. Taken together, these results imply that H2O2 is a critical component of neonatal HI injury, and GPx1 plays an important role in the defense against this H2O2 and is thereby neuroprotective.

Multiple pathways of neuroprotection against oxidative stress and excitotoxic injury in immature primary hippocampal neurons

In the immature brain hydrogen peroxide accumulates after excitotoxic hypoxia-ischemia and is neurotoxic. Immature hippocampal neurons were exposed to N-methyl-D-aspartate (NMDA), a glutamate agonist, and hydrogen peroxide (H(2)O(2)) and the effects of free radical scavenging and transition metal chelation on neurotoxicity were studied. alpha-Phenyl-N-tert.-butylnitrone (PBN), a known superoxide scavenger, attenuated both H(2)O(2) and NMDA mediated toxicity. Treatment with desferrioxamine (DFX), an iron chelator, at the time of exposure to H(2)O(2) was ineffective, but pretreatment was protective. DFX also protected against NMDA toxicity. TPEN, a metal chelator with higher affinities for a broad spectrum of transition metal ions, also protected against H(2)O(2) toxicity but was ineffective against NMDA induced toxicity. These data suggest that during exposure to free radical and glutamate agonists, the presence of iron and other free metal ions contribute to neuronal cell death. In the immature nervous system this neuronal injury can be attenuated by free radical scavengers and metal chelators.

Nitric oxide is protective in listeric meningoencephalitis of rats

The bacterium Listeria monocytogenes causes meningoencephalitis in humans. In rodents, listeriosis is associated with granulomatous lesions in the liver and the spleen, but not with meningoencephalitis. Here, infant rats were infected intracisternally to generate experimental listeric meningoencephalitis. Dose-dependent effects of intracisternal inoculation with L. monocytogenes on survival and activity were noted; 10(4) L. monocytogenes organisms induced a self-limiting brain infection. Bacteria invaded the basal meninges, chorioid plexus and ependyme, spread to subependymal tissue and hippocampus, and disappeared by day 7. This was paralleled by recruitment and subsequent disappearance of macrophages expressing inducible nitric oxide synthase (iNOS) and nitrotyrosine accumulation, an indication of nitric oxide (NO.) production. Treatment with the spin-trapping agent alpha-phenyl-tert-butyl nitrone (PBN) dramatically increased mortality and led to bacterial numbers in the brain 2 orders of magnitude higher than in control animals. Treatment with the selective iNOS inhibitor L-N(6)-(1-iminoethyl)-lysine (L-NIL) increased mortality to a similar extent and led to 1 order of magnitude higher bacterial counts in the brain, compared with controls. The numbers of bacteria that spread to the spleen and liver did not significantly differ among L-NIL-treated, PBN-treated, and control animals. Thus, the infant rat brain is able to mobilize powerful antilisterial mechanisms, and both reactive oxygen and NO. contribute to Listeria growth control.