Morphology of the cloaca in the estuarine crocodile, Crocodylus porosus, and its plastic response to salinity

The cloacal complex of Crocodylus porosus is composed of three chambers (proctodaeum, urodaeum, and coprodaeum) separated by tight, muscular sphincters. The proctodaeum is proximal to the cloacal vent and houses the genitalia. The urodaeum is the largest chamber, is capable of storing large quantities of urine, and is lined with an epithelium with the capacity for transepithelial water and ion exchange. The coprodaeum, the most orad cloacal chamber, is a small, only marginally expandable chamber that has an epithelium composed almost entirely of mucus-secreting cells. The coprodaeum and lower intestine are reported to be the site(s) for urine modification in birds and bladderless lizards. A radiographic trace of urine storage in C. porosus kept for 2 months under hyperosmotic conditions showed no signs of retrograde movement of urine into the coprodaeum or rectum. Instead, urine was stored in the urodaeum of C. porosus. Examination of the mucosal surface of the urodaeum by SEM showed a plastic response to environmental salinity, with a possible increase in surface area in animals kept in hyperosmotic water compared with animals from fresh water. We propose the urodaeum as the primary site for postrenal modification of urine in C, porosus. (C) 2000 Wiley-Liss, Inc.

Conductivity, NMR and crystallographic study of N,N,N,N-tetramethylammonium dicyanamide plastic crystal phases: an archetypal ambient temperature plastic electrolyte material

N,N,N,N-Tetramethylammonium dicyanamide (Me(4)NDCA) has been examined via differential scanning calorimetry (DSC), thermogravimetric analysis, conductivity, single crystal X-ray diffraction and H-1 nuclear magnetic resonance (NMR) analyses, and was found to be highly conductive in the solid state (sigma = 10(-3) S cm(-2) at 420 K) and to also exhibit unusual plastic crystal behaviour. To investigate the correlation between such behaviour and the occurrence of molecular rotations in the crystal, H-1 NMR second moment measurements are compared with calculated values predicted from the crystal structure. While DSC analysis indicates a number of solid-solid transitions at ambient temperatures, subsequent H-1 NMR analysis of the Me4N+ cation shows that a variety of rotational motions become active at low (

A numerical study of effect of grain boundaries on elastic and plastic properties in nanocomposite materials

Nanocomposite materials have received considerable attention in recent years due to their novel properties. Grain boundaries are considered to play an important role in nanostructured materials. This work focuses on the finite element analysis of the effect of grain boundaries on the overall mechanical properties of aluminium/alumina composites. A grain boundary is incorporated into the commonly used unit cell model to investigate its effect on material properties. By combining the unit cell model with an indentation model, coupled with experimental indentation measurements, the ''effective'' plastic property of the grain boundary is estimated. In addition, the strengthening mechanism is also discussed based on the Estrin-Mecking model.

Descriptive findings on the morphology of dendritic spines in the rat medial amygdala

The rat posterodorsal medial amygdala (MePD) is a brain area in which gonadal hormones induce notable plastic effects in the density of dendritic spines. Dendritic spines are post-synaptic specializations whose shape and spacing change neuronal excitability. Our aim was to obtain new data on the dendritic spines morphology and density from MePD neurons using the carbocyanine dye Dil under confocal microscopy. In adult male rats, the dendritic spine density of the medial branches of the left MePD (mean +/- SD) was 1.15 +/- 0.67 spines/dendritic mu m. From the total sampled, approximately 53% of the spines were classified as thin, 22.5% as ""mushroom-like"", and 21.5% as stubby/wide. Other spine shapes (3%) included those ramified, with a filopodium-like or a gemule appearance, and others with a protruding spinule. Additional experiment joining Dil and synaptophysin (a pre-synaptic protein) labeling suggested synaptic sites on dendritic shafts and spines. Dendritic spines showed synaptophysin puncta close to their head and neck, although some spines had no evident labeled puncta on them or, conversely, multiple puncta appeared upon one spine. These results advance previous light microscopy results by revealing features and complexities of the dendritic spines at the same time that give new insight on the possible synaptic organization of the adult rat MePD. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Qualitative analysis of hippocampal plastic changes in rats with epilepsy supplemented with oral omega-3 fatty acids

Studies have provided evidence of the important effects of omega-3 fatty acid on the brain in neurological conditions, including epilepsy. Previous data have indicated that omega-3 fatty acids lead to prevention of status epilepticus-associated neuropathological changes in the hippocampal formation of rats with epilepsy. Omega-3 fatty acid supplementation has resulted in extensive preservation of GABAergic cells in animals with epilepsy. This study investigated the interplay of these effects with neurogenesis and brain-derived neurotrophic factor (BDNF). The results clearly showed a positive effect of long-term omega-3 fatty acid supplementation on brain plasticity in animals with epilepsy. Enhanced hippocampal neurogenesis and BDNF levels and preservation of interneurons expressing parvalbumin were observed. Parvalbumin-positive cells were identified as surviving instead of newly formed cells. Additional investigations are needed to determine the electrophysiological properties of the newly formed cells and to clarify whether the effects of omega-3 fatty acids on brain plasticity are accompanied by functional gain in animals with epilepsy. (C) 2009 Elsevier Inc. All rights reserved.

Lethal lesions and amputation caused by plastic debris and fishing gear on the loggerhead turtle Caretta caretta (Linnaeus, 1758). Three case reports from Terceira Island, Azores (NE Atlantic)

Copyright © 2014 Elsevier Science Ltd.

A arte/expressão plástica numa inter-relação com a matemática/geometria: Um projeto no jardim de infância

Dissertação apresentada à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Educação Artística, na Especialização de Artes Plásticas na Educação

Joining the online video conversation? Discourse and practices of European political institutions and politicians on YouTube

To mimic the online practices of citizens has been declared an imperative to improve communication and extend participation. This paper seeks to contribute to the understanding of how European discourses praising online video as a communication tool have been translated into actual practices by politicians, governments and organisations. By contrasting official documents with YouTube activity, it is argued that new opportunities for European political communication are far from being fully embraced, much akin to the early years of websites. The main choice has been to use YouTube channels fundamentally for distribution and archiving, thus neglecting its social media features. The disabling of comments by many heads of state and prime ministers - and, in 2010, the European Commission - indicates such an attitude. The few attempts made to foster citizen engagement, in particular during elections, have had limited success, given low participation numbers and lack of argument exchange.

Epigenetic and transcriptional signatures of stable versus plastic differentiation of proinflammatory gd T cell subsets

Two distinct subsets of γδ T cells that produce interleukin 17 (IL-17) (CD27(-) γδ T cells) or interferon-γ (IFN-γ) (CD27(+) γδ T cells) develop in the mouse thymus, but the molecular determinants of their functional potential in the periphery remain unknown. Here we conducted a genome-wide characterization of the methylation patterns of histone H3, along with analysis of mRNA encoding transcription factors, to identify the regulatory networks of peripheral IFN-γ-producing or IL-17-producing γδ T cell subsets in vivo. We found that CD27(+) γδ T cells were committed to the expression of Ifng but not Il17, whereas CD27(-) γδ T cells displayed permissive chromatin configurations at loci encoding both cytokines and their regulatory transcription factors and differentiated into cells that produced both IL-17 and IFN-γ in a tumor microenvironment.

Bisphenol A migration from plastic materials: direct insight of ecotoxicity in Daphnia magna

Bisphenol A (BPA) is an endocrine disrupting chemical (EDC) whose migration from food packaging is recognized worldwide. However, the real overall food contamination and related consequences are yet largely unknown. Among humans, children’s exposure to BPA has been emphasized because of the immaturity of their biological systems. The main aim of this study was to assess the reproductive impact of BPA leached from commercially available plastic containers used or related to child nutrition, performing ecotoxicological tests using the biomonitoring species Daphnia magna. Acute and chronic tests, as well as single and multigenerational tests were done. Migration of BPA from several baby bottles and other plastic containers evaluated by GC-MS indicated that a broader range of foodstuff may be contaminated when packed in plastics. Ecotoxicological test results performed using defined concentrations of BPA were in agreement with literature, although a precocious maturity of daphnids was detected at 3.0 mg/L. Curiously, an increased reproductive output (neonates per female) was observed when daphnids were bred in the polycarbonate (PC) containers (145.1±4.3 % to 264.7±3.8 %), both in single as in multigenerational tests, in comparison with the negative control group (100.3±1.6 %). A strong correlated dose-dependent ecotoxicological effect was observed, providing evidence that BPA leached from plastic food packaging materials act as functional estrogen in vivo at very low concentrations. In contrast, neonate production by daphnids cultured in polypropylene and non-PC bottles was slightly but not significantly enhanced (92.5±2.0 % to 118.8±1.8 %). Multigenerational tests also revealed magnification of the adverse effects, not only on fecundity but also on mortality, which represents a worrying trend for organisms that are chronically exposed to xenoestrogens for many generations. Two plausible explanations for the observed results could be given: a non-monotonic dose–response relationship or a mixture toxicity effect.

Lightweight amorphous silicon photovoltaic modules on flexible plastic substrate

Solar cells on lightweight and flexible substrates have advantages over glass-or wafer-based photovoltaic devices in both terrestrial and space applications. Here, we report on development of amorphous silicon thin film photovoltaic modules fabricated at maximum deposition temperature of 150 degrees C on 100 mu m thick polyethylene-naphtalate plastic films. Each module of 10 cm x 10 cm area consists of 72 a-Si:H n-i-p rectangular structures with transparent conducting oxide top electrodes with Al fingers and metal back electrodes deposited through the shadow masks. Individual structures are connected in series forming eight rows with connection ports provided for external blocking diodes. The design optimization and device performance analysis are performed using a developed SPICE model.

Acrylic adhesives in the polyolefins joining

The mechanical behaviour of single lap adhesive joints was characterized, using two commercial acrylic adhesives. For this purpose the surfaces were cleaned and abraded using fine grit abrasives. The effect of temperature and moisture in the mechanical strength was, also, evaluated. For this characterization, mechanical tests were carried out according procedure and geometry foreseen by ASTM D3163-01 [1] and ASTM D4501-01 [2] standards. The results show that it is possible to get good strengths without great surface preparation. The temperature and moisture effect observed don’t seem to be relevant for the mechanical behaviour.

Drilling of fibre reinforced plastic laminates

The use of fibre reinforced plastics – FRP’s – in structures is under a considerable increase. Advantages of their use are related with their low weight, high strength and stiffness. The improvement of the dynamic characteristics has been profitable for aeronautics, automobile, railway, naval and sporting goods industries. Drilling is a widely used machining technique as it is needed to assemble parts in a structure. This is a unique machining process, characterized by the existence of two different mechanisms: extrusion by the drill chisel edge and cutting by the rotating cutting lips. Drilling raises particular problems that can reduce mechanical and fatigue strength of the parts. In this work, quasi-isotropic hybrid laminates with 25% of carbon fibre reinforced plies and 4 mm thickness are produced, tested and drilled. Three different drill geometries are compared. Results considered are the interlaminar fracture toughness in Mode I – GIc –, thrust force during drilling and delamination extent after drilling. A bearing test is performed to evaluate tool influence on the load carrying capacity of the plate. Results consider the influence of drill geometry on delamination. A correlation linking plate damage to bearing test results is presented.

Joining models with stair nesting

In the stair nested designs with u factors we have u steps and a(1), ... , a(u) "active" levels. We would have a(1) observations with different levels for the first factor each of them nesting a single level of each of the remaining factors; next a(2) observations with level a(1) + 1 for the first factor and distinct levels for the second factor each nesting a fixed level of each of the remaining factors, and so on. So the number of level combinations is Sigma(u)(i=1) a(i). In meta-analysis joint treatment of different experiments is considered. Joining the corresponding models may be useful to carry out that analysis. In this work we want joining L models with stair nesting.