Wind Forced Variability in Eddy Formation, Eddy Shedding, and the Separation of the East Australian Current

The East Australian Current (EAC), like many other subtropical western boundary currents, is believed to be penetrating further poleward in recent decades. Previous observational and model studies have used steady state dynamics to relate changes in the westerly winds to changes in the separation behavior of the EAC. As yet, little work has been undertaken on the impact of forcing variability on the EAC and Tasman Sea circulation. Here using an eddy‐permitting regional ocean model, we present a suite of simulations forced by the same time‐mean fields, but with different atmospheric and remote ocean variability. These eddy‐permitting results demonstrate the nonlinear response of the EAC to variable, nonstationary inhomogeneous forcing. These simulations show an EAC with high intrinsic variability and stochastic eddy shedding. We show that wind stress variability on time scales shorter than 56 days leads to increases in eddy shedding rates and southward eddy propagation, producing an increased transport and southward reach of the mean EAC extension. We adopt an energetics framework that shows the EAC extension changes to be coincident with an increase in offshore, upstream eddy variance (via increased barotropic instability) and increase in subsurface mean kinetic energy along the length of the EAC. The response of EAC separation to regional variable wind stress has important implications for both past and future climate change studies

Between-gender differences in vigilance do not necessarily lead to differences in foraging-vigilance tradeoffs

When prey are time limited in their access to food, any trade-off involving time should ultimately affect their intake rate. In many herbivores, males and females experience different ecological pressures affecting their survival and reproduction because of differences in morphology, physiology and energy/nutrient requirements. If males and females have different vigilance strategies that affect their intake rates differently, they will suffer different foraging costs. This is particularly relevant in sexually monomorphic herbivores, where the two sexes have similar basal energy/nutrient requirements and risk of predation. We investigated how gender, reproductive status, age, group size, predation risk, and food biomass affected vigilance, intake rate, and their trade-off in a monomorphic species, the plains zebra (Equus quagga). Males were more vigilant than females, and lactating females were less vigilant than other females; the levels of vigilance were low (ca. 10 % of feeding time). The effects on time spent feeding, bite rates and intake rates were small and statistically not significant. Reproductive status did not affect the strength of the relationship between vigilance and intake rate, but intake rates increased with group size and, for adult females, were higher in tall grass. While gender and reproductive status were major drivers of vigilance, and group size and food biomass of the rate of food intake, males and females adjust their bite rates and food intake with vigilance in similar ways. Our results support the hypothesis that in monomorphic animals, males and females seem to make similar trade-offs (i.e. adjustments) between vigilance and intake rate

Proteolytic enzyme and inhibitor levels in reindeer (Rangifer tarandus tarandus L.) vs. bovine longissimus muscle, as they relate to ageing rate and response

Eight reindeer bulls (age 1.5 years) and six Friesian bulls (age 1.5 years) were included in the study for comparison of tenderness. The reindeer were slaughtered at a commercial reindeer slaughter plant in northern Sweden and the Friesian bulls at a commercial slaughter plant in The Netherlands. Samples for determination of calpain/calpastatin activity were taken from the M. longtssimus (LO) within 1 h post mortem (p.m.), and at various times p.m. pH and temperature were registered in LO; ultimate pH values were measured at 24 h p.m. for beef and at 35 h p.m. for reindeer. At day 1 p.m., samples of LO from both carcass sides were excised, divided in two parts, vacuum packaged and stored at 0-2 °C. One part of each muscle was randomly sampled at 1, 3, 7 and 14 days p.m. for determination of shear force, proteolytic enzyme activity, myofibrillar protein degradation, collagen content and heat solubility. pH and temperature fall was faster in reindeer than in beef. Collagen content in reindeer muscle was found to be low but collagen was 4 times less soluble as compared with beef. Reindeer LO was found to be extremely tender, at 3 days p.m. shear force values were only 2-3 kg/cm2 (8-12 kg/cm2 for beef LO). In reindeer meat, the jJ.-calpain levels dropped to about 55% within 3 days. Troponin T and 30 kDa values were not related to changes in tenderness in reindeer meat. Cathepsin activities in reindeer were up to ten times higher than in beef. As in beef, cathepsin B+L levels in reindeer increased during storage, which is probably associated with a decrease in cystatin-like inhibitor levels

Structure, electrochemical properties and functionalization of amorphous CN films deposited by femtosecond pulsed laser ablation

Amorphous carbon nitride (a-C:N) material has attracted much attention in research and development. Recently, it has become a more promising electrode material than conventional carbon based electrodes in electrochemical and biosensor applications. Nitrogen containing amorphous carbon (a-C:N) thin films have been synthesized by femtosecond pulsed laser deposition (fs-PLD) coupled with plasma assistance through Direct Current (DC) bias power supply. During the deposition process, various nitrogen pressures (0 to 10 Pa) and DC bias (0 to ¿ 350 V) were used in order to explore a wide range of nitrogen content into the films. The structure and chemical composition of the films have been studied by using Raman spectroscopy, electron energy-loss spectroscopy (EELS) and high-resolution transmission electron microscopy (HRTEM). Increasing the nitrogen pressure or adding a DC bias induced an increase of the N content, up to 21 at.%. Nitrogen content increase induces a higher sp2 character of the film. However DC bias has been found to increase the film structural disorder, which was detrimental to the electrochemical properties. Indeed the electrochemical measurements, investigated by cyclic voltammetry (CV), demonstrated that a-C:N film with moderate nitrogen content (10 at.%) exhibited the best behavior, in terms of reversibility and electron transfer kinetics. Electrochemical grafting from diazonium salts was successfully achieved on this film, with a surface coverage of covalently bonded molecules close to the dense packed monolayer of ferrocene molecules. Such a film may be a promising electrode material in electrochemical detection of electroactive pollutants on bare film, and of biopathogen molecules after surface grafting of the specific affinity receptor.This work is produced with the financial support of the Future Program Lyon Saint-Etienne (PALSE) from the University of Lyon (ANR-11-IDEX-0007), under the “Investissements d'Avenir” program managed by the National Agency Research (ANR)

False claims about false memory research

Pezdek and Lam [Pezdek, K. & Lam, S. (2007). What research paradigms have cognitive psychologists used to study “False memory,” and what are the implications of these choices? Consciousness and Cognition] claim that the majority of research into false memories has been misguided. Specifically, they charge that false memory scientists have been (1) misusing the term “false memory,” (2) relying on the wrong methodologies to study false memories, and (3) misapplying false memory research to real world situations. We review each of these claims and highlight the problems with them. We conclude that several types of false memory research have advanced our knowledge of autobiographical and recovered memories, and that future research will continue to make significant contributions to how we understand memory and memory errors

The Ocean Reanalysis Intercomparison project (ORA-IP)

Uncertainty in ocean analysis methods and deficiencies in the observing system are major obstacles for the reliable reconstruction of the past ocean climate. The variety of existing ocean reanalyses is exploited in a multi-reanalysis ensemble to improve the ocean state estimation and to gauge uncertainty levels. The ensemble-based analysis of signal-to-noise ratio allows the identification of ocean characteristics for which the estimation is robust (such as tropical mixed-layer-depth, upper ocean heat content), and where large uncertainty exists (deep ocean, Southern Ocean, sea ice thickness, salinity), providing guidance for future enhancement of the observing and data assimilation systems

The Ocean Reanalyses Intercom parison Project (ORA - IP)

Uncertainty in ocean analysis methods and deficiencies in the observing system are major obstacles for the reliable reconstruction of the past ocean climate. The variety of existing ocean reanalyses is exploited in a multi-reanalysis ensemble to improve the ocean state estimation and to gauge uncertainty levels. The ensemble-based analysis of signal-to-noise ratio allows the identification of ocean characteristics for which the estimation is robust (such as tropical mixed-layer-depth,upper ocean heat content), and where large uncertainty exists (deep ocean, Southern Ocean, sea-ice thickness, salinity), providing guidance for future enhancement of the observing and data assimilation systems

Reconstructing extreme AMOC events through nudging of the ocean surface: a perfect model approach

While the Atlantic Meridional Overturning Circulation (AMOC) is thought to be a crucial component of the North Atlantic climate, past changes in its strength are challenging to quantify, and only limited information is available. In this study, we use a perfect model approach with the IPSL-CM5A-LR model to assess the performance of several surface nudging techniques in reconstructing the variability of the AMOC. Special attention is given to the reproducibility of an extreme positive AMOC peak from a preindustrial control simulation. Nudging includes standard relaxation techniques towards the sea surface temperature and salinity anomalies of this target control simulation, and/or the prescription of the wind-stress fields. Surface nudging approaches using standard fixed restoring terms succeed in reproducing most of the target AMOC variability, including the timing of the extreme event, but systematically underestimate its amplitude. A detailed analysis of the AMOC variability mechanisms reveals that the underestimation of the extreme AMOC maximum comes from a deficit in the formation of the dense water masses in the main convection region, located south of Iceland in the model. This issue is largely corrected after introducing a novel surface nudging approach, which uses a varying restoring coefficient that is proportional to the simulated mixed layer depth, which, in essence, keeps the restoring time scale constant. This new technique substantially improves water mass transformation in the regions of convection, and in particular, the formation of the densest waters, which are key for the representation of the AMOC extreme. It is therefore a promising strategy that may help to better constrain the AMOC variability and other ocean features in the models. As this restoring technique only uses surface data, for which better and longer observations are available, it opens up opportunities for improved reconstructions of the AMOC over the last few decades