Traditional timber frame walls: mechanical behavior analysis and retrofitting

Timber frame construction is characteristic of several historic city centres as well as of vernacular architecture in several countries around the world, either motivated by the availability of materials and construction traditions or by the need of reducing the seismic vulnerability of buildings, namely in south European countries, where this construction technique was adopted for seismic-resistance purposes. From past earthquakes, it has been seen that timber frame construction can be viewed as an interesting technology as it has exhibited a very reasonable behaviour when compared to other traditional construction techniques such as masonry walls. This chapter provides an overview of the main insights on the seismic performance of timber frame buildings from the evidences of past earthquakes and provides the main results of recent research focused on the in-plane cyclic behavior of timber frame walls with distinct geometrical configurations. Additionally, the main seismic performance indexes of timber frame walls, both unreinforced and retrofitted, are presented and discussed in detail.

Morfologia da plântula em desenvolvimento de Astrocaryum aculeatum Meyer (Arecaceae)

Astrocaryum aculeatum (tucumã) é uma palmeira amazônica, cuja polpa dos frutos, rica em vitamina A, pode ser consumida ao natural ou na forma de sorvete, suco, licor e doce. Sua propagação é demorada, existindo pouco conhecimento sobre a germinação das sementes e o desenvolvimento das plântulas. O presente trabalho teve como objetivo descrever o processo germinativo das sementes dessa espécie, submetidas ou não ao pré-tratamento de embebição, e caracterizar cronologicamente os estádios morfológicos da plântula. A germinação das sementes é do tipo adjacente ligulada, criptocotiledonar e hipógea. O tempo para alcançar cada estádio foi menor para as sementes embebidas, indicando efeito benéfico da embebição sobre a velocidade do processo germinativo, com média de emergência do pecíolo cotiledonar de 99 dias e de completa expansão da primeira folha bífida de 253 dias.

Aging and Alzheimer's disease: Searching for novel molecular cues

Tese de Doutoramento em Ciências da Saúde

Morfologia Floral de uma População de Tucumã, Astrocaryum aculeatum Meyer (Arecaceae) na Amazônia Central

Foi realizada a descrição morfológica das inflorescências, bem como das flores pistiladas e estaminadas, de uma população de Astrocaryum aculeatum Meyer, no Campus do Instituto Nacional de Pesquisas da Amazônia - INPA. A inflorescência é do tipo panícula de espigas, pedunculada, interfoliar e apresenta tamanho médio de 146 ± 20,3 cm. Uma bráctea lenhosa provida de espinhos em toda superfície externa protege a inflorescência. Estas apresentam cerca de 375 ± 49,5 ráquilas. Foi estimado de 500 a 1.200 flores pistiladas e 190.000 a 260.000 flores estaminadas por inflorescência. As flores estaminadas apresentam um padrão de cores que variam do vinho ao creme e também com tons mesclados de vinho e creme.

Haematophagic behavior in laboratory of Lutzomyia cruzi (Mangabeira) (Diptera: Psychodidae) in relation to three mammalian blood sources in Manaus, Brazil

The sand fly Lutzomyia cruzi is considered as one of vectors of visceral leishmaniasis in Brazil. This work examined optimum feeding age, feeding time, host preference, fecundity rates, and female blood meal volume taken by single females from a closed colony of L. cruzi. Mean feeding time was longer on hamsters, 6.6 minutes, than on humans, 5.7 minutes. 49.1% of the 48h-old flies fed on humans and 43.3% of 72h-old flies fed on hamsters. Of a total of 120 females, 61% fed on humans and 25% fed on hamsters. Total fecundity was significantly higher in females fed on hamster than on human or opossum. Laboratory-reared L. cruzi females fed earlier, more promptly, and preferably on humans than on hamsters when offered these blood-meal sources simultaneously. The blood-meal volume is higher in females fed on hamsters than other hosts (human and opossum).

Produção de matéria seca e eficiência nutricional para P, Ca e Mg em leguminosas herbáceas

As leguminosas para adubação verde têm sido introduzidas nos sistemas agrícolas para a recuperação de solos desgastados pelo uso intensivo. O objetivo desse trabalho foi avaliar a resposta de leguminosas herbáceas à aplicação de calcário e fósforo sobre a produção de biomassa e eficiência nutricional para o P, Ca e Mg. O experimento foi desenvolvido em casa-de-vegetação do Departamento de Ciência do Solo da Universidade Federal Rural da Amazônia, utilizando-se um Latossolo Amarelo distrófico coletado na profundidade de 0 - 20 cm, em Belém, PA. O delineamento experimental usado foi o de blocos ao acaso, com arranjo de tratamentos em um fatorial 3³, onde foram comparadas três espécies de leguminosas: mucuna preta (Stizolobium atterrimum), mucuna cochinchinensis (Stilozobium cochinchinensis) e feijão-de-porco (Canavalia ensiformes); três níveis de calagem: de calcário dolomítico (0, 4 e 8 t.ha-1) e de fósforo (0, 25 e 45 mg.dm-3), com quatro repetições cada um. Mucuna cochinchinensis e o feijão de porco produziram maiores quantidades de biomassa vegetal do que a mucuna preta, sendo que a primeira espécie acumulou maior quantidade de P e a segunda maior quantidade de Ca. Mucuna cochinchinensis apresentou maior eficiência de utilização de P, Ca e Mg na ausência da calagem. Nos solos intemperizados com baixa concentração de P, Ca e Mg, o feijão-de-porco e a mucuna cochinchinensis poderão ter melhor desempenho do que a mucuna preta, visto que apresentaram maior eficiência de translocação e de utilização desses nutrientes, respectivamente.

Surface plasmon resonance-coupled photoluminescence and resistive switching behavior of pulsed laser-deposited Ag:SiC nanocermet thin films

In this study, Ag:SiC nanocermets were prepared via rapid thermal annealing (RTA) of pulsed laser-deposited SiC/Ag/SiC trilayers grown on Si substrate. Atomic force microscope images show that silver nanoparticles (Ag NPs) are formed after RTA, and the size of NPs increases with increasing Ag deposition time (t Ag). Sharp dip observed in the reflectance spectra confirmed the existence of Ag surface plasmons (SPs). The infrared transmission spectra showed an intense and broad absorption band around 780–800 cm−1 that can be assigned to Si-C stretching vibration mode. Influence of t Ag on the spectral characteristics of SP-enhanced photoluminescence (PL) and electrical properties of silicon carbide (SiC) films has been investigated. The maximum PL enhancement by 5.5 times for Ag:SiC nanocermets is achieved when t Ag ≈ 50 s. This enhancement is due to the strong resonant coupling between SiC and the SP oscillations of the Ag NPs. Presence of Ag NPs in SiC also induces a forming-free resistive switching with switching ratio of 2 × 10−2. The analysis of I–V curves demonstrates that the trap-controlled space-charge-limited conduction with filamentary model is the governing mechanism for the resistive switching in nanocerment thin films.

Neural correlates of face familiarity in institutionally reared children with distinctive, atypical social behavior

Although the impact of early adverse experience on neural processing of face familiarity has been studied, research has not taken into account disordered child behavior. This work compared the neural processing of familiar versus strangers' faces in 47 institutionalized children with a mean age of 54 months to determine the effects of (a) the presence versus absence of atypical social behavior and (b) inhibited versus indiscriminant atypical behavior. Results revealed a pattern of cortical hypoactivation in institutionalized children manifesting atypical social behavior and that inhibited children displayed larger neural response to a caregiver's face than to the stranger's, while indiscriminant children did not discriminate between stimuli. These findings suggest that neural correlates of face familiarity are associated with social functioning in institutionalized children.

Attachment style impacts behavior and early oculomotor response to positive, but not negative, pictures

The present study investigated whether oculomotor behavior is influenced by attachment styles. The Relationship Scales Questionnaire was used to assess attachment styles of forty-eight voluntary university students and to classify them into attachment groups (secure, preoccupied, fearful, and dismissing). Eye-tracking was recorded while participants engaged in a 3-seconds free visual exploration of stimuli presenting either a positive or a negative picture together with a neutral picture, all depicting social interactions. The task consisted in identifying whether the two pictures depicted the same emotion. Results showed that the processing of negative pictures was impermeable to attachment style, while the processing of positive pictures was significantly influenced by individual differences in insecure attachment. The groups highly avoidant regarding to attachment (dismissing and fearful) showed reduced accuracy, suggesting a higher threshold for recognizing positive emotions compared to the secure group. The groups with higher attachment anxiety (preoccupied and fearful) showed differences in automatic capture of attention, in particular an increased delay preceding the first fixation to a picture of positive emotional valence. Despite lenient statistical thresholds induced by the limited sample size of some groups (p < 0.05 uncorrected for multiple comparisons), the current findings suggest that the processing of positive emotions is affected by attachment styles. These results are discussed within a broader evolutionary framework.

Analysis of toxicity on Bacillus sphaericus from amazonian soils to Anopheles darlingi and Culex quinquefasciatus larvae

Bioassays under laboratory conditions aiming to determine the larvicidal activity of Bacillus sphaericus were carried out on Anopheles darlingi and Culex quinquefasciatus. In order to estimate the toxicity through median lethal concentration (LC50) and the relative potency of the strains to B. sphaericus standard strain 2362, probit analysis was performed utilizing the POLO-PC program. The findings of LC50 pointed out high effectiveness on strains IB15 (0.040 ppm), IB19 and S1116 (0.048 ppm), IB16 (0.052 ppm) and S265 (0.057 ppm). Strain IB15 presented nearly 50% more potency than strain 2362 in bioassays conducted on A. darlingi. It was observed that IB16 and S1116 strains were the most powerful against C. quinquefasciatus, showing to be about 300-400% stronger than 2362 strain. The results show that laboratory conditioned evaluation can be an important way to select promising bacteria with entomopathogenic action on biolarvicides production for use on mosquitoes breeding sites.

In vitro mechanical fatigue behavior of poly-ε-caprolactone macroporous scaffolds for cartilage tissue engineering: Influence of pore filling by a poly(vinyl alcohol) gel

Polymeric scaffolds used in regenerative therapies are implanted in the damaged tissue and subjected to repeated loading cycles. In the case of articular cartilage engineering, an implanted scaffold is typically subjected to long term dynamic compression. The evolution of the mechanical properties of the scaffold during bioresorption has been deeply studied in the past, but the possibility of failure due to mechanical fatigue has not been properly addressed. Nevertheless, the macroporous scaffold is susceptible to failure after repeated loading-unloading cycles. In this work fatigue studies of polycaprolactone scaffolds were carried by subjecting the scaffold to repeated compression cycles in conditions simulating the scaffold implanted in the articular cartilage. The behaviour of the polycaprolactone sponge with the pores filled with a poly(vinyl alcohol) gel simulating the new formed tissue within the pores was compared with that of the material immersed in water. Results were analyzed with Morrow’s criteria for failure and accurate fittings are obtained just up to 200 loading cycles. It is also shown that the presence of poly(vinyl alcohol) increases the elastic modulus of the scaffolds, the effect being more pronounced with increasing the number of freeze/thawing cycles.

Influence of design parameters on the mechanical behavior and porosity of braided fibrous stents

In spite of all innovations in stent design, commonly used metallic stents present several problems such as corrosion, infection and restenosis, leading to health complications or even death of patients. In this context, the present paper reports a systematic investigation on designing and development of 100% fiber based stents, which can eliminate or minimize the problems with existing metallic stents. For this purpose, braided stents were produced by varying different materials, structural and process parameters such as mono-filament type and diameter, braiding angle and mandrel diameter. The influence of these design parameters on mechanical behavior as well as stent's porosity was thoroughly investigated, and suitable parameters were selected for developing a stentwith mechanical characteristics and porosity matching with the commercial stents. According to the experimental results, the best performance was achieved with a polyester stent designed with 0.27 mm monofilament diameter, braiding angle of 35° and mandrel diameter of 6 mm, providing similar properties to commercial Nitinol stents.

Efeito da calagem e da correção dos teores de Ca e Mg do solo sobre o crescimento de mudas de angelim-pedra (Dinizia excelsa Ducke)

O conhecimento dos requerimentos nutricionais das espécies e de suas respostas à correção do substrato é fundamental para a produção de mudas de qualidade. O objetivo deste trabalho foi avaliar o efeito de diferentes tipos de calcário e da correção da deficiência de Ca e Mg sobre o desenvolvimento de mudas de angelim-pedra (D. excelsa) em casa de vegetação, utilizando-se como substrato Latossolo Amarelo. Foram testados três tipos de calcário e fornecimento de Ca e Mg por meio de fontes não-corretivas da acidez em três relações Ca:Mg. Os tratamentos consistiram de T0 & testemunha; T1 & calcário dolomítico; T2 & calcário magnesiano; T3 & calcário calcítico; T4 & Ca e Mg na relação 3:1; T5 & Ca e Mg na relação 9:1; e T6 & Ca e Mg na relação 15:1. O delineamento experimental foi de blocos ao acaso, com cinco repetições, totalizando 35 parcelas, cada uma delas com 3 mudas. O substrato foi adubado com doses equivalentes a 100-250-150 e 15 kg ha-1 de N, P2O5, K2O e S, respectivamente e com solução de micronutrientes (3 mL de Chelamix L-1 de água destilada). Foram avaliadas: a altura da planta, o diâmetro do colo, matéria seca da parte aérea, matéria seca da raiz, matéria seca total, relação raiz/parte aérea e conteúdos de nutrientes da parte aérea das plantas. De modo geral, a aplicação de calcário favoreceu o crescimento de D. excelsa, sendo os melhores resultados obtidos com a aplicação de calcário magnesiano na relação 9:1.

Potencial de resposta à adubação para N, P, K, Ca e Mg em cupuaçueiros avaliados por diferentes normas DRIS

O potencial de resposta à adubação é uma ferramenta utilizada para a interpretação dos valores dos índices DRIS, de forma que pode ser útil para verificar se diferentes grupos de normas resultam em diagnósticos distintos ou semelhantes entre si. Neste sentido, objetivou-se avaliar o comportamento do diagnóstico nutricional, submetidos a cinco grupos de normas DRIS. Para isto, amostras foliares de cupuaçueiros foram coletadas de pomares comerciais, cuja idade das plantas variou de 5 a 18 anos, sob monocultivo e sistemas agroflorestais (SAF's), obtendo-se para cada relação nutricional entre os nutrientes N, P, K, Ca, Mg, as normas DRIS bivariadas, as quais foram obtidas para o conjunto das populações monitoradas e para subpopulações específicas. As diferentes normas DRIS resultaram em diagnósticos semelhantes para N, P e Ca, enquanto que para K e Mg os diagnósticos produzidos distinguiram-se entre as normas resultando em desvios nutricionais.

Enhanced resistive switching and multilevel behavior in bilayered HfAlO/HfAlOx structures for non-volatile memory applications

In this work, hafnium aluminum oxide (HfAlO) thin films were deposited by ion beam sputtering deposition technique on Si substrate. The presence of oxygen vacancies in the HfAlOx layer deposited in oxygen deficient environment is evidenced from the photoluminescence spectra. Furthermore, HfAlO(oxygen rich)/HfAlOx(oxygen poor) bilayer structures exhibit multilevel resistive switching (RS), and the switching ratio becomes more prominent with increasing the HfAlO layer thickness. The bilayer structure with HfAlO/HfAlOx thickness of 30/40 nm displays the enhanced multilevel resistive switching characteristics, where the high resistance state/ intermediate resistance state (IRS) and IRS/low resistance state resistance ratios are 102 and 5 105 , respectively. The switching mechanisms in the bilayer structures were investigated by the temperature dependence of the three resistance states. This study revealed that the multilevel RS is attributed to the coupling of ionic conduction and the metallic conduction, being the first associated to the formation and rupture of conductive filaments related to oxygen vacancies and the second with the formation of a metallic filament. Moreover, the bilayer structures exhibit good endurance and stability in time.