Role of Environment and Experimenter in Reproducibility of Behavioral Studies With Laboratory Mice

Behavioral phenotyping of mice has received a great deal of attention during the past three decades. However, there is still a pressing need to understand the variability caused by environmental and biological factors, human interference, and poorly standardized experimental protocols. The inconsistency of results is often attributed to the inter-individual difference between the experimenters and environmental conditions. The present work aims to dissect the combined influence of the experimenter and the environment on the detection of behavioral traits in two inbred strains most commonly used in behavioral genetics due to their contrasting phenotypes, the C57BL/6J and DBA/2J mice. To this purpose, the elevated O-maze, the open field with object, the accelerating rotarod and the Barnes maze tests were performed by two experimenters in two diverse laboratory environments. Our findings confirm the well-characterized behavioral differences between these strains in exploratory behavior, motor performance, learning and memory. Moreover, the results demonstrate how the experimenter and the environment influence the behavioral tests with a variable-dependent effect, often with mutually exclusive contributions. In this context, our study highlights how both the experimenter and the environment can have an impact on the strain effect size without altering the direction of the conclusions. Importantly, the general agreement on the results is reached by converging evidence from multiple measures addressing the same trait. In conclusion, the present work elucidates the contribution of both the experimenter and the laboratory environment in the intricate field of reproducibility in mouse behavioral phenotyping.Peer reviewe

Phase composition and transformations in magnetron-sputtered (Al,V)2O3 coatings

Coatings of (Al1-xVx)2O3, with x ranging from 0 to 1, were deposited by pulsed DC reactive sputter deposition on Si(100) at a temperature of 550 {\deg}C. XRD showed three different crystal structures depending on V-metal fraction in the coating: {\alpha}-V2O3 rhombohedral structure for 100 at.% V, a defect spinel structure for the intermediate region, 63 - 42 at.% V. At lower V-content, 18 and 7 at.%, a gamma-alumina-like solid solution was observed, shifted to larger d-spacing compared to pure {\gamma}-Al2O3. The microstructure changes from large columnar faceted grains for {\alpha}-V2O3 to smaller equiaxed grains when lowering the vanadium content toward pure {\gamma}-Al2O3. Annealing in air resulted in formation of V2O5 crystals on the surface of the coating after annealing to 500 {\deg}C for 42 at.% V and 700 {\deg}C for 18 at.% V metal fraction respectively. The highest thermal stability was shown for pure {\gamma}-Al2O3-coating, which transformed to {\alpha}-Al2O3 after annealing to 1100{\deg} C. Highest hardness was observed for the Al-rich oxides, ~24 GPa. The latter decreased with increasing V-content, larger than 7 at.% V metal fraction. The measured hardness after annealing in air decreased in conjunction with the onset of further oxidation of the coatings

Fear and its implications for stock markets

The value of stocks, indices and other assets, are examples of stochastic processes with unpredictable dynamics. In this paper, we discuss asymmetries in short term price movements that can not be associated with a long term positive trend. These empirical asymmetries predict that stock index drops are more common on a relatively short time scale than the corresponding raises. We present several empirical examples of such asymmetries. Furthermore, a simple model featuring occasional short periods of synchronized dropping prices for all stocks constituting the index is introduced with the aim of explaining these facts. The collective negative price movements are imagined triggered by external factors in our society, as well as internal to the economy, that create fear of the future among investors. This is parameterized by a ``fear factor'' defining the frequency of synchronized events. It is demonstrated that such a simple fear factor model can reproduce several empirical facts concerning index asymmetries. It is also pointed out that in its simplest form, the model has certain shortcomings.Comment: 5 pages, 5 figures. Submitted to the Proceedings of Applications of Physics in Financial Analysis 5, Turin 200

A comparison of the DNA binding and bending capacities and the oligomeric states of the immunity repressors of heteroimmune coliphages P2 and WPhi

Bacteriophages P2 and WΦ are heteroimmune members of the P2-like family of temperate Escherichia coli phages. Temperate phages can grow lytically or form lysogeny after infection. A transcriptional switch that contains two con-vergent promoters, Pe and Pc, and two repressors regulate what life mode to enter. The immunity repressor C is the first gene of the lysogenic operon, and it blocks the early Pe promoter. In this work, some characteristics of the C proteins of P2 and WΦ are compared. An in vivo genetic analysis shows that WΦ C, like P2 C, has a strong dimerization activity in the absence of its DNA target. Both C proteins recognize two directly repeated sequences, termed half-sites and a strong bending is induced in the respective DNA target upon binding. P2 C is unable to bind to one half-site as opposed to WΦ, but both half-sites are required for repression of WΦ Pe. A reduction from three to two helical turns between the centers of the half-sites in WΦ has no significant effect on the capacity to repress Pe. However, the protein–DNA complexes formed differ, as determined by electrophoretic mobility shift experiments. A difference in spontaneous phage production is observed in isogenic lysogens

Mechanisms Underlying the Response to Inequitable Outcomes in Chimpanzees, Pan Troglodytes

Several species of non-human primates respond negatively to inequitable outcomes, a trait shared with humans. Despite previous research, questions regarding the response to inequity remain. In this study, we replicated the methodology from previous studies to address four questions related to inequity. First, we explored the impact of basic social factors. Second, we addressed whether negative responses to inequity require a task, or exist when rewards are given for ‘free’. Third, we addressed whether differences in the experimental procedure or the level of effort required to obtain a reward affected responses. Finally, we explored the interaction between ‘individual’ expectations (based on one’s own previous experience) and ‘social’ expectations (based on the partner’s experience). These questions were investigated in 16 socially-housed adult chimpanzees using eight conditions that varied across the dimensions of reward, effort, and procedure. Subjects did respond to inequity, but only in the context of a task. Differences in procedure and level of effort required did not cause individuals to change their behavior. Males were more sensitive to social than to individual expectation, while females were more sensitive to individual expectation. Finally, subjects also increased refusals when receiving a better reward than their partner, which has not been seen previously. These results indicate that chimpanzees are more sensitive to reward inequity than procedures, and that there is interaction between social and individual expectations that depends upon social factors

Synchronization Model for Stock Market Asymmetry

The waiting time needed for a stock market index to undergo a given percentage change in its value is found to have an up-down asymmetry, which, surprisingly, is not observed for the individual stocks composing that index. To explain this, we introduce a market model consisting of randomly fluctuating stocks that occasionally synchronize their short term draw-downs. These synchronous events are parameterized by a ``fear factor'', that reflects the occurrence of dramatic external events which affect the financial market.Comment: 4 pages, 4 figure

Direct observation of mono-vacancy and self-interstitial recovery in tungsten

Reliable and accurate knowledge of the physical properties of elementary point defects is crucial for predictive modeling of the evolution of radiation damage in materials employed in harsh conditions. We have applied positron annihilation spectroscopy to directly detect mono-vacancy defects created in tungsten through particle irradiation at cryogenic temperatures, as well as their recovery kinetics. We find that efficient self-healing of the primary damage takes place through Frenkel pair recombination already at 35 K, in line with an upper bound of 0.1 eV for the migration barrier of self-interstitials. Further self-interstitial migration is observed above 50 K with activation energies in the range of 0.12-0.42 eV through the release of the self-interstitial atoms from impurities and structural defects and following recombination with mono-vacancies. Mono-vacancy migration is activated at around 550 K with a migration barrier of E-m(V) = 1.85 +/- 0.05 eV. (C) 2019 Author(s).Peer reviewe

Latent ice recrystallization inhibition activity in nonantifreeze proteins : Ca2+-activated plant lectins and cation-activated antimicrobial peptides

Organisms living in polar regions have evolved a series of antifreeze (glyco) proteins (AFGPs) to enable them to survive by modulating the structure of ice. These proteins have huge potential for use in cellular cryopreservation, ice-resistant surfaces, frozen food, and cryosurgery, but they are limited by their relatively low availability and questions regarding their mode of action. This has triggered the search for biomimetic materials capable of reproducing this function. The identification of new structures and sequences capable of inhibiting ice growth is crucial to aid our understanding of these proteins. Here, we show that plant c-type lectins, which have similar biological function to human c-type lectins (glycan recognition) but no sequence homology to AFPs, display calcium-dependent ice recrystallization inhibition (IRI) activity. This IRI activity can be switched on/off by changing the Ca2+ concentration. To show that more (nonantifreeze) proteins may exist with the potential to display IRI, a second motif was considered, amphipathicity. All known AFPs have defined hydrophobic/hydrophilic domains, rationalizing this choice. The cheap, and widely used, antimicrobial Nisin was found to have cation-dependent IRI activity, controlled by either acid or addition of histidine-binding ions such as zinc or nickel, which promote its amphipathic structure. These results demonstrate a new approach in the identification of antifreeze protein mimetic macromolecules and may help in the development of synthetic mimics of AFPs

Anomalous Transport in Conical Granular Piles

Experiments on 2+1-dimensional piles of elongated particles are performed. Comparison with previous experiments in 1+1 dimensions shows that the addition of one extra dimension to the dynamics changes completely the avalanche properties, appearing a characteristic avalanche size. Nevertheless, the time single grains need to cross the whole pile varies smoothly between several orders of magnitude, from a few seconds to more than 100 hours. This behavior is described by a power-law distribution, signaling the existence of scale invariance in the transport process.Comment: Accepted in PR

Absolute quantification of perfusion by dynamic susceptibility contrast MRI using Bookend and VASO steady-state CBV calibration: a comparison with pseudo-continuous ASL.

Dynamic susceptibility contrast MRI (DSC-MRI) tends to return elevated estimates of cerebral blood flow (CBF) and cerebral blood volume (CBV). In this study, subject-specific calibration factors (CFs), based on steady-state CBV measurements, were applied to rescale the absolute level of DSC-MRI CBF