Physiological stress responses in the warm-water fish matrinxã (Brycon amazonicus) subjected to a sudden cold shock

The present work evaluated several aspects of the generalized stress response [endocrine (cortisol), metabolic (glucose), hematologic (hematocrit and hemoglobin) and cellular (HSP70)] in the Amazonian warm-water fish matrinxã (Brycon amazonicus ) subjected to an acute cold shock. This species farming has been done in South America, and growth and feed conversion rates have been interesting. However, in subtropical areas of Brazil, where the water temperature can rapidly change, high rates of matrinxã mortality have been associated with abrupt decrease in the water temperature. Thus, we subjected matrinxã to a sudden cold shock by transferring the fish directly to tanks in which the water temperature was 10oC below the initial conditions (cold shock from 28ºC to 18oC). After 1h the fish were returned to the original tanks (28ºC). The handling associated with tank transfer was also imposed on control groups (not exposed to cold shock). While exposure to cold shock did not alter the measured physiological conditions within 1h, fish returned to the ambient condition (water at 28º C) significantly increased plasma cortisol and glucose levels. Exposure to cold shock and return to the warm water did not affect HSP70 levels. The increased plasma cortisol and glucose levels after returning the fish to warm water suggest that matrinxã requires cortisol and glucose for adaptation to increased temperature.

Microstructure evolution of martensitic Ti-6Al-4V alloy during warm deformation

The microstructure evolution of martensitic Ti-6Al-4V alloy was investigated through uniaxial hot compression at 700°C and a strain rate of 10-3 s-1. A combination of scanning electron microscopy observation in conjunction with high resolution electron back scattered diffraction (EBSD) was used to characterize the microstructure in detail. The development of the microstructure displayed continuous fragmentation of martensitic laths with increasing strain (i.e. continuous dynamic recrystallization), concurrently with decomposition of supersaturated martensite resulting in the formation of equiaxed grains. At a strain of 0.8, an ultrafine equiaxed grained structure with mostly high angle grain boundaries was successfully obtained. The current work proposes a novel approach to produce equiaxed ultrafine grains in a Ti-6Al-4V alloy through thermomechanical processing of a martensitic starting microstructure. © (2014) Trans Tech Publications, Switzerland.

Basal metabolic rate, food intake, and body mass in cold- and warm-acclimated Garden Warblers

We address the question of whether physiological flexibility in relation to climate is a general feature of the metabolic properties of birds. We tested this hypothesis in hand-raised Garden Warblers (Sylvia borin), long-distance migrants, which normally do not experience great temperature differences between summer and winter. We maintained two groups of birds under cold and warm conditions for 5 months, during which their body mass and food intake were monitored. When relatedness (siblings vs. non-siblings) of the experimental birds was taken into account, body mass in cold-acclimated birds was higher than in warm-acclimated birds. BMR, measured at the end of the 5-month temperature treatment, was also higher in the cold- than the warm-acclimated group. Migrant birds thus seem to be capable of the same metabolic cold-acclimation response as has been reported in resident birds. The data support the hypothesis that physiological flexibility is a basic trait of the metabolic properties of birds.

Warm deformation and annealing behaviour of iron-silicon-(carbon) steel sheets

Single pass warm rolling and compression experiments were carried out from ambient to 800°C for ultra-low carbon (ULC) steel with ∼100 ppm carbon and interstitial free (IF) steels, both with two levels of silicon. Subsequently, annealing was done in order to recrystallize the deformed specimens. The main purpose of this study was to understand the effects of rolling temperature and silicon on stress responses and textures. This study comprises two main themes: flow stress and strain rate sensitivity during compression and shear banding and textures in warm rolled specimens. The effects of deformation temperature on in-grain shear bands were different between ULC-Si and IF-Si steels. As in previous work with more conventional steels, in-grain shear bands in the IF grade had low sensitivity to rolling temperature, while those in the ULC grade depended significantly on the deformation temperature. However, the temperature profile of shear banding in the ULC grade was approximately 150°C higher than in previous work. Deformation and recrystallisation textures for both IF and ULC grades depended on their rolling temperatures. The variation of both grain size and texture after annealing can be explained by the rise and fall of in-grain shear banding activity which is related to the strain rate sensitivity.

Enhanced mechanical response of an ultrafine grained Ti-6Al-4V alloy produced through warm symmetric and asymmetric rolling

An equiaxed ultrafine-grained (UFG) microstructure was successfully produced in a Ti-6Al-4V alloy with an average grain size of 110-230. nm through symmetric and asymmetric warm rolling of a martensitic starting microstructure. The UFG material displayed a combination of ultrahigh strength and ductility at room temperature. Compared with the conventional symmetric rolling, the asymmetric rolling process led to a more pronounced effect of microstructure refinement and a higher tensile ductility. The optimum mechanical response was obtained though the asymmetric rolling at 70% reduction, offering an ultimate tensile strength of 1365. MPa and a total elongation of ~23%. Apart from the magnitude of grain refinement, the inclination of basal texture component from the normal towards the rolling direction during asymmetric rolling and possible strain induced β to martensite transformation may concurrently contribute to a remarkable tensile strength-ductility balance.

The deep end: pedagogy and the public pool

Diving in to New Materialist theory, this paper explores what might be learnt at a public swimming pool. Writing, sitting, thinking and swimming, the learner enters new spaces and atmospheres, where learning emerges as unpredictable and involving a whole range of human and non human bodies. Public spaces, where we can think about causality and design without the strictures of school curriculum, may emerge as key sites for new understandings of learning where abiding humanist preoccupations can slip away. This presentation involves movement, touching, flesh, smelling, silicone, cotton and water. Be prepared to get changed!

The effect of double - blind carbohydrate ingestion during 60 km of self-paced exercise in warm ambient conditions

This study evaluated double blind ingestions of placebo (PLA) versus 6% carbohydrate (CHO) either as capsules (c) or beverage (b) during 60 km self-paced cycling in the heat (32°C and 50% relative humidity). Ten well-trained males (mean ± SD: 26±3 years; 64.5±7.7 kg and 70.7±8.8 ml.kg-1.min-1 maximal oxygen consumption) completed four separate 60 km time trials (TT) punctuated by 1 km sprints (14, 29, 44, 59 km) whilst ingesting either PLAb or PLAc or CHOb or CHOc. The TT was not different among treatments (PLAb 130.26 11.2 min, CHOb 140.5±18.1 min, PLAc 143.1±29.2 min, CHOc 137.3±20.1 min; P>0.05). Effect size (Cohen's d) for time was only moderate when comparing CHOb - PLAb (d = 0.68) and PLAb - PLA c (d = 0.57) whereas all other ES were 'trivial' to 'small'. Mean speed throughout the trial was significantly higher for PLAb only (P<0.05). Power output was only different (P<0.05) between the sprints and low intensity efforts within and across conditions. Core and mean skin temperatures were similar among trials. We conclude that CHO ingestion is of little or no benefit as a beverage compared with placebo during 60 km TT in the heat.

Host cell remodelling in malaria parasites: a new pool of potential drug targets

When in their human hosts, malaria parasites spend most of their time housed within vacuoles inside erythrocytes and hepatocytes. The parasites extensively modify their host cells to obtain nutrients, prevent host cell breakdown and avoid the immune system. To perform these modifications, malaria parasites export hundreds of effector proteins into their host cells and this process is best understood in the most lethal species to infect humans, Plasmodium falciparum. The effector proteins are synthesized within the parasite and following a proteolytic cleavage event in the endoplasmic reticulum and sorting of mature proteins into the correct vesicular trafficking pathway, they are transported to the parasite surface and released into the vacuole. The effector proteins are then unfolded before extrusion across the vacuole membrane by a unique translocon complex called Plasmodium translocon of exported proteins. After gaining access to the erythrocyte cytoplasm many effector proteins continue their journey to the erythrocyte surface by utilising various membranous structures established by the parasite. This complex trafficking pathway and a large number of the effector proteins are unique to Plasmodium parasites. This pathway could, therefore, be developed as new drug targets given that protein export and the functional role of these proteins are essential for parasite survival. This review explores known and potential drug targetable steps in the protein export pathway and strategies for discovering novel drug targets.

Swimming lessons : learning, new materialisms, posthumanism, and post qualitative research emerge through a pool poem

This article shifts from the formal learning spaces of school anduniversity to an Australian public swimming pool to playfullyengage some of the dilemmas that recent theory poses forcurriculum studies. The article enacts multiple diffractions(Barad, 2007) as theory becomes swimming and swimmingbecomes theory, and ideas and movements are themselvesdiffracted or changed by the writing of a poem. What does thepool teach us? What is learnt at the pool? How does learningemerge at the pool? Physics, chemistry, biology, and artistrycombine, as multiple human and non-human bodies intra-act(Barad, 2007), calling each other into being in this exploration ofhow distributed agencies and fractal causalities (Bennett, 2010)change how learning might be thought, represented, andswum. The poem incorporated here serves as provocation andinspiration for other scholars struggling with these educationaldilemmas and interested in arts-based research.