Mice Reach Higher Visual Sensitivity at Night by Using a More Efficient Behavioral Strategy

Circadian clocks predictively adjust the physiology of organisms to the day/night cycle. The retina has its own clock, and many diurnal changes in its physiology have been reported. However, their implications for retinal functions and visually guided behavior are largely unresolved. Here, we study the impact of diurnal rhythm on the sensitivity limit of mouse vision. A simple photon detection task allowed us to link well-defined retinal output signals directly to visually guided behavior. We show that visually guided behavior at its sensitivity limit is strongly under diurnal control, reaching the highest sensitivity and stability at night. The diurnal differences in visual sensitivity did not arise in the retina, as assessed by spike recordings from the most sensitive retinal ganglion cell types: ON sustained, OFF sustained, and OFF transient alpha ganglion cells. Instead, we found that mice, as nocturnal animals, use a more efficient search strategy for visual cues at night. Intriguingly, they can switch to the more efficient night strategy even at their subjective day after first having performed the task at night. Our results exemplify that the shape of visual psychometric functions depends robustly on the diurnal state of the animal, its search strategy, and even its diurnal history of performing the task. The results highlight the impact of the day/night cycle on high-level sensory processing, demonstrating a direct diurnal impact on the behavioral strategy of the animal.Peer reviewe

Vanguard projects as relay races: A historical case study on the building of Eurocan pulp and paper mill, 1965–1970

Previous research recognises the strategic role of vanguard projects in providing their initiators with avenues for entering new markets or gaining mastery over innovative technologies. This study makes a contribution to this research by focusing on the extent to which vanguard projects are under control and serve the interests of their principal initiators and the other actors involved. Simultaneously, the present study contributes to project management research by applying historical case study methodology on Eurocan, a vanguard project that a major Finnish forest industry firm Enso established in the mid-1960s to the wilderness of British Columbia, Canada. Our historical analysis encourages regarding vanguard projects as relay races in which several actors participate, largely in unanticipated ways. This is especially because the initiation of vanguard projects appears to be characterised by both the heterogeneity of the actors involved, a wide variety of actions taken by these actors to increase their centrality in the project organisation as well as abrupt changes among them and their relative importance over the project lifecycle. Together these characteristics make vanguard projects particularly prone to influence from external actors and events.</p

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Selective detection of morphine in the presence of paracetamol with anodically pretreated dual layer Ti/tetrahedral amorphous carbon electrodes

We investigated the effect of anodic treatment of titanium/tetrahedral amorphous carbon electrodes on the electrochemical detection of morphine and paracetamol. The anodic treatment caused both oxidation of the carbon and, more importantly, exposure and oxidation of the underlying Ti layer. This treatment anodically shifted the oxidation potential of paracetamol while that of morphine remained unaffected. The resulting electrode also showed better selectivity than a ta-C electrode without Ti. After anodic treatment at 2.5 V, selective detection of morphine with a physiologically meaningful detection limit of 9.8 nM and a linear range of 0.1-10 mu M was obtained in the presence of 100 mu M paracetamol.Peer reviewe

Simultaneous electrochemical detection of tramadol and O-desmethyltramadol with Nafion-coated tetrahedral amorphous carbon electrode

Tramadol (TR) is a member of the opioid family and is widely used for pain treatment in clinical patient care. The analgesic effect of tramadol is induced primarily by its main metabolite Odesmethyltramadol (ODMT). Due to interindividual differences in the TR metabolism to ODMT, the responses to TR vary highly between patients. Thus, a fast and selective method for simultaneous detection of TR and ODMT would increase the patient safety and pain treatment efficacy. In this study, a tetrahedral amorphous carbon (ta-C) electrode coated with a thin dip-coated recast Nafion membrane was fabricated for selective electrochemical determination of TR and ODMT. With this Nafion/ta-C electrode, simultaneous detection of TR and ODMT was achieved with linear ranges of 1-12.5 mu M and 1-15 mu M, respectively. The limits of detection were 131 nM for TR and 209 nM for ODMT. Both analytes were also measured in the presence of several common interferents, demonstrating the high selectivity of the fabricated electrode. In addition, the effect of pH on the peak potential was studied to observe the electrochemical behavior of the analytes at the electrode. Finally, clinically relevant concentrations of TR and ODMT were simultaneously detected from diluted human plasma to assess the applicability of the electrode in real samples. The fabricated Nafion/ta-C electrode was found successful in the simultaneous electrochemical detection of TR and ODMT in both buffer solution and in human plasma. (C) 2018 Elsevier Ltd. All rights reserved.Peer reviewe