New insights into ion regulation of cephalopod molluscs: a role of epidermal ionocytes in acid-base regulation during embryogenesis

The constraints of an active life in a pelagic habitat led to numerous convergent morphological and physiological adaptations that enable cephalopod molluscs and teleost fishes to compete for similar resources. Here we show for the first time that such convergent developments are also found in the ontogenetic progression of ion regulatory tissues: as in teleost fish epidermal ionocytes scattered on skin and yolk sac of cephalopod embryos appear to be responsible for ionic and acid-base regulation before gill epithelia become functional. Ion and acid-base regulation is crucial in cephalopod embryos, as they are surrounded by a hypercapnic egg fluid with a pCO2 of 0.2-0.4 kPa. Epidermal ionocytes were characterized via immunohistochemistry, in situ hybridization and vital dye staining techniques. We found one group of cells that is recognized by Concavalin A and MitoTracker, which also expresses Na+/H+ exchangers (NHE) and Na+/K+-ATPase. Similar to findings obtained in teleosts these NHE3-rich cells take up sodium in exchange for protons, illustrating the energetic superiority of NHE based proton excretion in marine systems. In vivo electrophysiological techniques demonstrated that acid equivalents are secreted by the yolk and skin integument. Intriguingly, epidermal ionocytes of cephalopod embryos are ciliated as demonstrated by scanning electron microscopy suggesting a dual function of epithelial cells in water convection and ion regulation. These findings add significant knowledge to our mechanistic understanding of hypercapnia tolerance in marine organisms, as it demonstrates that marine taxa which were identified as powerful acid-base regulators during hypercapnic challenges already exhibit strong acid-base regulatory abilities during embryogenesis

Repeatability and reproducibility of the measurement of prepreg tack following ASTM D8336: Results of a round-robin study

This study reports the findings from a round robin test exercise investigating ASTM D8336, a method for the measurement of tack of prepregs applicable to automated material placement technologies. Twelve participants tested two prepreg materials in a core study of three temperature and deposition/peel rate combinations, and five participants conducted an extended study based on a test matrix of four temperatures and four rates. In the core study, the repeatability coefficient of variation of obtained tack values ranged from 6.06 % to 15.08 %, while the reproducibility coefficient of variation ranged from 12.37 % to 32.37 %. The probable dominant causes for the observed variability are the limited accuracy of control and measurement of specimen temperature, of compaction force, and of humidity. Using time-temperature superposition, tack mastercurves were constructed from the extended study, identifying values of peak tack, the rate at peak tack and the width of the tack mastercurve, as well as the 95 % confidence and prediction bands. Across all materials and participants, 93.3 % of the repeats from the core study lay within the 95 % prediction bands, supporting the view 2 that a mastercurve provides a greater degree of useful information at a comparable effort for data acquisition

Family context, television and perceived values. A cross-cultural study with adolescents [Contexto familiar, televisión y valores percibidos. Un estudio transcultural con adolescentes]

Earthquake protection of historical buildings is fundamental for the economy and development of a country and is a topic of intensive research among the scientific community. Two different material models and approaches such as 3D Limit Analysis and nonlinear Finite Element Method are used and compared for the seismic evaluation of an old masonry Cathedral in Colima, Mexico. It has been strongly damaged by a M7.6 earthquake in 1941, generating strong damage to the main facade with the collapse of the left tower. It was damaged again by a similar event of M7.5 in 2003. Both events mainly damaged the main facade including both bell-towers. In this paper, firstly, the Cathedral is completely modeled and a macro-element representing the observed most damaged part is selected. The seismic assessment results by both, Limit Analysis and nonlinear Finite Element approaches are able to simulate the observed failure mechanisms at the frontal facade and the obtained seismic coefficients are in good agreement. Moreover, the advantages and disadvantages through the seismic analysis process corresponding to the pre-processing, analysis and post-processing by the use of both approaches are detailed. " 2014 Elsevier Ltd.",,,,,,"10.1016/j.engfailanal.2014.12.003",,,"http://hdl.handle.net/20.500.12104/41429","http://www.scopus.com/inward/record.url?eid=2-s2.0-84920895742&partnerID=40&md5=925665ceaa4fa022fea0e5fba62a0b27",,,,,,,,"Engineering Failure Analysis",,"2

Facade seismic failure simulation of an old Cathedral in Colima, Mexico by 3D Limit Analysis and nonlinear Finite Element Method

Earthquake protection of historical buildings is fundamental for the economy and development of a country and is a topic of intensive research among the scientific community. Two different material models and approaches such as 3D Limit Analysis and nonlinear Finite Element Method are used and compared for the seismic evaluation of an old masonry Cathedral in Colima, Mexico. It has been strongly damaged by a M7.6 earthquake in 1941, generating strong damage to the main façade with the collapse of the left tower. It was damaged again by a similar event of M7.5 in 2003. Both events mainly damaged the main façade including both bell-towers. In this paper, firstly, the Cathedral is completely modeled and a macro-element representing the observed most damaged part is selected. The seismic assessment results by both, Limit Analysis and nonlinear Finite Element approaches are able to simulate the observed failure mechanisms at the frontal façade and the obtained seismic coefficients are in good agreement. Moreover, the advantages and disadvantages through the seismic analysis process corresponding to the pre-processing, analysis and post-processing by the use of both approaches are detailed. © 2014 Elsevier Ltd

Behavioural responses of juvenile cuttlefish (Sepia officinalis) to local water movements

Physiological studies have shown that the epidermal head and arm lines in cephalopods are a mechanoreceptive system that is similar to the fish and amphibian lateral lines (. A lateral line analogue in cephalopods: Water waves generate microphonic potentials in the epidermal head lines of Sepia officinalis and Lolliguncula brevis. J. Comp. Physiol. A 164:1–5.); however, the biological significance of the epidermal lines remains unclear. To test whether cuttlefish show behavioural responses to local water movements, juvenile Sepia officinalis were exposed to local sinusoidal water movements of different frequencies (0.01–1000 Hz) produced by a vibrating sphere. Five behavioural responses were recorded: body pattern changing, moving, burrowing, orienting, and swimming. Cuttlefish responded to a wide range of frequencies (20–600 Hz), but not to all of the frequencies tested within that range. No habituation to repeated stimuli was seen. Results indicate that cuttlefish can detect local water movements (most likely with the epidermal head and arm lines) and are able to integrate that information into behavioural responses