In permanent transit: discourses and maps of the intercultural experience

Instituto Polit��cnico do Porto. Instituto Superior de Contabilidade e Administra����o do Porto

Influence of environmental temperature and humidity on the acute ventilatory response to exercise in asthmatic adolescents

Asthma is a chronic inflammatory disorder of the respiratory airways affecting people of all ages, and constitutes a serious public health problem worldwide (6). Such a chronic inflammation is invariably associated with injury and repair of the bronchial epithelium known as remodelling (11). Inflammation, remodelling, and altered neural control of the airways are responsible for both recurrent exacerbations of asthma and increasingly permanent airflow obstruction (11, 29, 34). Excessive airway narrowing is caused by altered smooth muscle behaviour, in close interaction with swelling of the airway walls, parenchyma retractile forces, and enhanced intraluminal secretions (29, 38). All these functional and structural changes are associated with the characteristic symptoms of asthma ��� cough, chest tightness, and wheezing ���and have a significant impact on patients��� daily lives, on their families and also on society (1, 24, 29). Recent epidemiological studies show an increase in the prevalence of asthma, mainly in industrial countries (12, 25, 37). The reasons for this increase may depend on host factors (e.g., genetic disposition) or on environmental factors like air pollution or contact with allergens (6, 22, 29). Physical exercise is probably the most common trigger for brief episodes of symptoms, and is assumed to induce airflow limitations in most asthmatic children and young adults (16, 24, 29, 33). Exercise-induced asthma (EIA) is defined as an intermittent narrowing of the airways, generally associated with respiratory symptoms (chest tightness, cough, wheezing and dyspnoea), occurring after 3 to 10 minutes of vigorous exercise with a maximal severity during 5 to 15 minutes after the end of the exercise (9, 14, 16, 24, 33). The definitive diagnosis of EIA is confirmed by the measurement of pre- and post-exercise expiratory flows documenting either a 15% fall in the forced expiratory volume in 1 second (FEV1), or a ���15 to 20% fall in peak expiratory flow (PEF) (9, 24, 29). Some types of physical exercise have been associated with the occurrence of bronchial symptoms and asthma (5, 15, 17). For instance, demanding activities such as basketball or soccer could cause more severe attacks than less vigorous ones such as baseball or jogging (33). The mechanisms of exercise-induced airflow limitations seem to be related to changes in the respiratory mucosa induced by hyperventilation (9, 29). The heat loss from the airways during exercise, and possibly its post-exercise rewarming may contribute to the exercise-induced bronchoconstriction (EIB) (27). Additionally, the concomitant dehydration from the respiratory mucosa during exercise leads to an increased interstitial osmolarity, which may also contribute to bronchoconstriction (4, 36). So, the risk of EIB in asthmatically predisposed subjects seems to be higher with greater ventilation rates and the cooler and drier the inspired air is (23). The incidence of EIA in physically demanding coldweather sports like competitive figure skating and ice hockey has been found to occur in up to 30 to 35% of the participants (32). In contrast, swimming is often recommended to asthmatic individuals, because it improves the functionality of respiratory muscles and, moreover, it seems to have a concomitant beneficial effect on the prevalence of asthma exacerbations (14, 26), supporting the idea that the risk of EIB would be smaller in warm and humid environments. This topic, however, remains controversial since the chlorified water of swimming pools has been suspected as a potential trigger factor for some asthmatic patients (7, 8, 20, 21). In fact, the higher asthma incidence observed in industrialised countries has recently been linked to the exposition to chloride (7, 8, 30). Although clinical and epidemiological data suggest an influence of humidity and temperature of the inspired air on the bronchial response of asthmatic subjects during exercise, some of those studies did not accurately control the intensity of the exercise (2, 13), raising speculation of whether the experienced exercise overload was comparable for all subjects. Additionally, most of the studies did not include a control group (2, 10, 19, 39), which may lead to doubts about whether asthma per se has conditioned the observed results. Moreover, since the main targeted age group of these studies has been adults (10, 19, 39), any extrapolation to childhood/adolescence might be questionable regarding the different lung maturation. Considering the higher incidence of asthma in youngsters (30) and the fact that only the works of Amirav and coworkers (2, 3) have focused on this age group, a scarcity of scientific data can be identified. Additionally, since the main environmental trigger factors, i.e., temperature and humidity, were tested separately (10, 28, 39) it would be useful to analyse these two variables simultaneously because of their synergic effect on water and heat loss by the airways (31, 33). It also appears important to estimate the airway responsiveness to exercise within moderate environmental ranges of temperature and humidity, trying to avoid extreme temperatures and humidity conditions used by others (2, 3). So, the aim of this study was to analyse the influence of moderate changes in air temperature and humidity simultaneously on the acute ventilatory response to exercise in asthmatic children. To overcome the above referred to methodological limitations, we used a 15 minute progressive exercise trial on a cycle ergometer at 3 different workload intensities, and we collected data related to heart rate, respiratory quotient, minute ventilation and oxygen uptake in order to ensure that physiological exercise repercussions were the same in both environments. The tests were done in a ���normal��� climatic environment (in a gymnasium) and in a hot and humid environment (swimming pool); for the latter, direct chloride exposition was avoided.

Aproveitamento e valoriza����o de res��duos provenientes da produ����o de Biodiesel

Com o desenvolvimento econ��mico das ��ltimas d��cadas, a gest��o de recursos energ��ticos �� um desafio que a sociedade moderna enfrenta. Assim, actualmente h�� a necessidade da procura de novas fontes de energia, fontes de energia renov��veis. Sendo o biodiesel uma fonte de energia renov��vel, a sua crescente produ����o ir�� trazer um aumento da produ����o de res��duos, como o glicerol e ��cidos gordos. �� pois importante reduzir/valorizar estes res��duos de forma a impedir a sua acumula����o ao longo do tempo. A valoriza����o destes res��duos �� o objectivo principal deste trabalho. A primeira parte consistiu na esterifica����o de ��cidos gordos livres com glicerol, na presen��a de um catalisador ��cido, para a produ����o de monoglicer��deos. Foram utilizados diferentes tipos de mat��rias-primas: glicerol (76,3%) e res��duo de ��cidos gordos (20,8%), fornecidos pela empresa SOCIPOLE SA, glicerol puro (92,2%) e ��cido oleico puro (93,1%). Os catalisadores usados foram o cloreto de zinco comercial e o ��cido p-tolueonossulf��nico comercial. N��o foram efectuadas an��lises espec��ficas aos monoglicer��deos, o produto foi caracterizado pelo ��ndice de acidez. Aparentemente, a maior convers��o de ��cidos gordos foi obtida no ensaio de esterifica����o de ��cidos gordos com glicerol, ambos da SOCIPOLE SA. No entanto, este n��o serviu como termo de compara����o com os outros devido �� forma����o de uma fase s��lida (pol��mero). Relativamente aos outros ensaios, com raz��o molar glicerol/��cidos gordos de 1:3, o melhor resultado foi obtido na reac����o de glicerol da SOCIPOLE SA com ��cido oleico puro, na presen��a do catalisador ��cido p-toluenossulf��nico, �� temperatura de 106,3��C e tempo de reac����o de 4h30min, sendo a convers��o final de ��cido oleico 80,7%. Na segunda parte foi feito o estudo da esterifica����o de ��cidos gordos livres com metanol, na presen��a de ��cido sulf��rico, para a produ����o de biodiesel utilizando ��cidos gordos fornecidos pela empresa SOCIPOLE SA, ��cidos gordos derivados dos sab��es de um res��duo de glicerol fornecido pelo Laborat��rio de Tecnologia Qu��mica, Professora Doutora L��dia Vasconcelos do ISEP e ��cidos gordos derivados dos sab��es do glicerol bruto, fornecido pela empresa SOCIPOLE SA. Os ensaios foram efectuados a 65��C, com uma agita����o de 120rpm e uma raz��o molar ��cidos gordos/metanol de 1:3. Verificou-se que o ��ndice de acidez do produto, depois de lavado e seco, diminu��a com o tempo de reac����o e na generalidade a percentagem de ��steres aumentava, observando-se que a partir das seis horas, a reac����o se tornava muito lenta. O estudo da raz��o ��cidos gordos/metanol, n��o permitiu tirar conclus��es. O melhor resultado obtido correspondeu a um produto com 96,2% de ��steres met��licos e 8,54mgKOH/gamostra de ��ndice de acidez, pelo que n��o pode ainda ser designado de biodiesel.

Estudo da valoriza����o de um res��duo de ��cidos gordos livres

Com o desenvolvimento econ��mico a gest��o de recursos �� um desafio que a sociedade moderna enfrenta. Um desenvolvimento sustent��vel, que procure satisfazer as necessidades da gera����o actual e futuras, �� fundamental. �� pois necess��rio encontrar novas fontes de energia e reduzir/valorizar res��duos. O objectivo deste trabalho prende-se com a valoriza����o de um res��duo de ��cidos gordos livres como fonte alternativa de energia. Estes ��cidos gordos s��o obtidos na purifica����o prim��ria da glicerina proveniente da produ����o de biodiesel por via alcalina, cedida pela empresa SOCIPOLE SA. Inicialmente separaram-se os ��cidos gordos livres e ��steres presentes na glicerina, e caracterizou-se o produto obtido. Efectuaram-se dois ensaios, obtendo-se 42,9% e 53,8% em massa de ��cidos gordos livres e 41,7% e 34,0% de ��steres no 1�� e 2�� ensaio respectivamente. Al��m dos ��steres e ��cidos gordos livres, no 1�� produto existem 15,4% de mat��ria n��o esterific��vel e no 2�� 12,2%. Na primeira parte do trabalho, estudou-se a possibilidade de utiliza����o directa deste produto como combust��vel. Determinou-se o PCI, obtendo-se 29,8 e 29,4 MJ/kg para o 1�� e 2�� ensaio respectivamente. Estes valores s��o superiores aos que se encontram no despacho 17313/2008 de 26 de Junho de 2008, para biogasolina e biodiesel (27,2 MJ/kg), significando que os ��cidos gordos livres separados t��m forte potencial para serem usados como combust��vel. Efectuou-se tamb��m um estudo de corros��o de a��o do corpo e tubos de uma caldeira atrav��s de ensaios de polariza����o, usando um Potenciostato/Galvanostato, e por varia����o da massa de amostras mergulhadas nos ��cidos gordos livres a 105��C e �� temperatura ambiente. Nas condi����es estudadas, os ��cidos gordos n��o promoveram corros��o nas amostras. Por fim, fez-se a combust��o de uma amostra dos ��cidos gordos livres num bico de Meeker e verificou-se a forma����o de dep��sitos equivalentes a 1,93% da massa inicial. Na segunda parte estudou-se a possibilidade de produzir biodiesel por esterifica����o, dos ��cidos gordos livres. Fez-se um estudo pr��vio para verificar qual a melhor raz��o molar de amostra/metanol a utilizar, optando-se por 1:6. Ap��s cinco etapas de esterifica����o, obteve-se um produto final com 85,6% de ��steres. N��o foram ent��o atingidos os 96,5% exigidos pela norma europeia EN 14214, devido �� presen��a de mat��ria n��o esterific��vel na mat��ria-prima, que n��o foi poss��vel separar totalmente do produto durante o processo (esterifica����o, lavagem e secagem). Pela an��lise de todos os par��metros, o produto obtido n��o pode ser considerado biodiesel, n��o sendo poss��vel ser comercializado como tal. A an��lise dos resultados aponta para a op����o da valoriza����o do res��duo de ��cidos gordos na queima directa em geradores e caldeiras que dever�� no entanto, ser precedida de um estudo mais detalhado que inclua a an��lise da constitui����o da mat��ria n��o esterific��vel, para garantir uma combust��o segura.

Predictors of adherence to the Mediterranean diet from the first to the second trimester of pregnancy

Background: Although changes in eating patterns may occur during gestation, predictors of these changes have not been explored. This study aimed to identify predictors of adherence to the Mediterranean diet (MD) from the first to second trimester of pregnancy. Methods: A prospective study was conducted with 102 pregnant women aged 18-40, from the city of Porto, Portugal. Socio-demographic and lifestyle characteristics were assessed through a questionnaire. Food consumption was assessed with a three-day food diary completed during the first and second trimesters. Participants were categorized according to their change in adherence to the MD into the negative change group (i.e., women who had low adherence in each trimester or had high adherence in the first trimester and then low adherence in the second) and the positive change group (i.e., women who had high adherence in both trimesters or had low adherence in the first trimester and then high adherence in the second). Conditional stepwise logistic regression models were performed to assess the potential predictors of negative MD change. Results: Among the 102 women, 39.2% had negative change from the first to the second trimester. The logistic model��s results show that being married (OR=0.26, 95%CI: 0.10, 0.76) and having a higher intake of vegetables in the first trimester (OR=0.17, 95%CI: 0.10, 0.43) were associated with lower odds of having a negative change in adherence to the MD from the first to second trimester. Conclusion: Marital status and vegetable consumption seem to be associated with a lower occurrence of negative change in adherence to the MD from early to middle pregnancy.