408 research outputs found

    An exploratory policy analysis of electric vehicle sales competition and sensitivity to infrastructure in Europe

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    This research contributes to discussions about policy interventions to stimulate the transition of vehicle technology. Concentrating on passenger cars, an extensive system dynamics based market agent model of powertrain technology transitions within the EU up to 2050 is employed. With a focus on subsidy scenarios for both infrastructure deployment and vehicle purchase, and set within the context of the EU fleet emission regulations, we find that there are important interactions between different powertrain types and with infrastructure provision. For example, strong plug-in electric vehicle (PiEV) policy could inhibit the maturity of hydrogen fuel cell vehicles. Infrastructure provision is important for improving the utility of a PiEV, but we find that in the early market it may have a weaker correlation with uptake than other policy options, until the PiEV stock share is over around 5%. Furthermore, an attempt to install a ratio of much more than one charge point per 10 PiEV may lead to little gains and high costs. PiEV sales are relatively insensitive at target levels over 25 PiEV per charge point. The results of our study can help policymakers to find the right balance and timing of measures targeting the transition towards low carbon alternative vehicles

    Ultraviolet radiation shapes seaweed communities

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    The assessment of circulating volume using inferior vena cava collapse index and carotid Doppler velocity time integral in healthy volunteers: a pilot study

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    International audienceBackground: Assessment of circulating volume and the requirement for fluid replacement are fundamental to resuscitation but remain largely empirical. Passive leg raise (PLR) may determine fluid responders while avoiding potential fluid overload. We hypothesised that inferior vena cava collapse index (IVCCI) and carotid artery blood flow would change predictably in response to PLR, potentially providing a non-invasive tool to assess circulating volume and identifying fluid responsive patients.Methods: We conducted a prospective proof of concept pilot study on fasted healthy volunteers. One operator measured IVC diameter during quiet respiration and sniff, and carotid artery flow. Stroke volume (SV) was also measured using suprasternal Doppler. Our primary endpoint was change in IVCCI after PLR. We also studied changes in IVCCI after “sniff”, and correlation between carotid artery flow and SV.Results: Passive leg raise was associated with significant reduction in the mean inferior vena cava collapsibility index from 0.24 to 0.17 (p < 0.01). Mean stroke volume increased from 56.0 to 69.2 mL (p < 0.01). There was no significant change in common carotid artery blood flow. Changes in physiology consequent upon passive leg raise normalised rapidly.Discussion: Passive leg raise is associated with a decrease of IVCCI and increase in stroke volume. However, the wide range of values observed suggests that factors other than circulating volume predominate in determining the proportion of collapse with respiration.Conclusion: In contrast to other studies, we did not find that carotid blood flow increased with passive leg raise. Rapid normalisation of post-PLR physiology may account for this

    Impact of gonadectomy on blood pressure regulation in ageing male and female rats

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    Sexual dimorphism in blood pressure has been associated with differential expression of the angiotensin II (AII) receptors and with activity of the nervous system. It is generally accepted that aging affects kidney function as well as autonomic nervous system and hormonal balance. Given that hypertension is more prevalent in men than women until women reach their seventh decade we hypothesised that females would be relatively protected from adverse effects of ageing compared to males, and that this would be mediated by the protective effect of ovarian steroids. Intact and gonadectomised male and female normotensive Wistar rats aged 6, 12 and 18 months were used to study renal function, blood pressure, heart rate and blood pressure variability. We observed that intact females had lower levels of proteinuria and higher (12.5%) creatinine clearance compared to intact males, and that this difference was abolished by castration but not by ovariectomy. Ovariectomy resulted in a change by 9% in heart rate, resulting in similar cardiovascular parameters to those observed in males or gonadectomised males. Spectral analysis of systolic blood pressure revealed that high frequency power spectra were significantly elevated in the females vs. males and were reduced by ovariectomy. Taken altogether the results show that females are protected from age-related declining renal function and to a lesser extent from rising blood pressure in comparison to males. Whilst ovariectomy had some deleterious effects in females, the strongest effects were associated with gonadectomy in males, suggesting a damaging effect of male hormones

    Ferritin immobilization on patterned poly(2-hydroxyethyl methacrylate) brushes on silicon surfaces from colloid system

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    In this paper, we describe a graft polymerization/solvent immersion method for generating poly(2-hydroxyethyl methacrylate) (PHEMA) brushes in various patterns. We used a novel fabrication process, involving very-large-scale integration and oxygen plasma treatment, to generate well-defined patterns of polymerized PHEMA on patterned Si(100) surfaces. We observed brush- and mushroom-like regions for the PHEMA brushes, with various pattern resolutions, after immersing wafers presenting lines of these polymers in MeOH and n-hexane, respectively. The interaction between PHEMA and ferritin protein sheaths in MeOH and n-hexane (good and poor solvent for PHEMA, respectively) was used to capture and release ferritins from fluidic system. The “tentacles” behaver for PHEMA brushes was found through various solvents in fluidic system. Using high-resolution scanning electron microscopy, we observed patterned ferritin Fe cores on the Si surface after pyrolysis of the patterned PHEMA brushes and ferritin protein sheaths, which verify the “tentacles” behaver for PHEMA brushes

    Species-speciWc defense strategies of vegetative versus reproductive blades of the PaciWc kelps Lessonia nigrescens and Macrocystis integrifolia

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    Chemical defense is assumed to be costly and therefore algae should allocate defense investments in a way to reduce costs and optimize their overall fitness. Thus, lifetime expectation of particular tissues and their contribution to the fitness of the alga may affect defense allocation. Two brown algae common to the SE Pacific coasts, Lessonia nigrescens Bory and Macrocystis integrifolia Bory, feature important ontogenetic differences in the development of reproductive structures; in L. nigrescens blade tissues pass from a vegetative stage to a reproductive stage, while in M. integrifolia reproductive and vegetative functions are spatially separated on different blades. We hypothesized that vegetative blades of L. nigrescens with important future functions are more (or equally) defended than reproductive blades, whereas in M. integrifolia defense should be mainly allocated to reproductive blades (sporophylls), which are considered to make a higher contribution to fitness. Herein, within-plant variation in susceptibility of reproductive and vegetative tissues to herbivory and in allocation of phlorotannins (phenolics) and N-compounds was compared. The results show that phlorotannin and N-concentrations were higher in reproductive blade tissues for both investigated algae. However, preferences by amphipod grazers (Parhyalella penai) for either tissue type differed between the two algal species. Fresh reproductive tissue of L. nigrescens was more consumed than vegetative tissue, while the reverse was found in M. integrifolia, thus confirming the original hypothesis. This suggests that future fitness function might indeed be a useful predictor of anti-herbivore defense in large, perennial kelps. Results from feeding assays with artificial pellets that were made with air-dried material and extract-treated Ulva powder indicated that defenses in live algae are probably not based on chemicals that can be extracted or remain intact after air-drying and grinding up algal tissues. Instead, anti-herbivore defense against amphipod mesograzers seems to depend on structural traits of living algae

    RNase L Mediated Protection from Virus Induced Demyelination

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    IFN-α/β plays a critical role in limiting viral spread, restricting viral tropism and protecting mice from neurotropic coronavirus infection. However, the IFN-α/β dependent mechanisms underlying innate anti-viral functions within the CNS are poorly understood. The role of RNase L in viral encephalomyelitis was explored based on its functions in inhibiting translation, inducing apoptosis, and propagating the IFN-α/β pathway through RNA degradation intermediates. Infection of RNase L deficient (RL−/−) mice with a sub-lethal, demyelinating mouse hepatitis virus variant revealed that the majority of mice succumbed to infection by day 12 p.i. However, RNase L deficiency did not affect overall control of infectious virus, or diminish IFN-α/β expression in the CNS. Furthermore, increased morbidity and mortality could not be attributed to altered proinflammatory signals or composition of cells infiltrating the CNS. The unique phenotype of infected RL−/− mice was rather manifested in earlier onset and increased severity of demyelination and axonal damage in brain stem and spinal cord without evidence for enhanced neuronal infection. Increased tissue damage coincided with sustained brain stem infection, foci of microglia infection in grey matter, and increased apoptotic cells. These data demonstrate a novel protective role for RNase L in viral induced CNS encephalomyelitis, which is not reflected in overall viral control or propagation of IFN-α/β mediated signals. Protective function is rather associated with cell type specific and regional restriction of viral replication in grey matter and ameliorated neurodegeneration and demyelination

    Barcoding T Cell Calcium Response Diversity with Methods for Automated and Accurate Analysis of Cell Signals (MAAACS)

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    International audienceWe introduce a series of experimental procedures enabling sensitive calcium monitoring in T cell populations by confocal video-microscopy. Tracking and post-acquisition analysis was performed using Methods for Automated and Accurate Analysis of Cell Signals (MAAACS), a fully customized program that associates a high throughput tracking algorithm, an intuitive reconnection routine and a statistical platform to provide, at a glance, the calcium barcode of a population of individual T-cells. Combined with a sensitive calcium probe, this method allowed us to unravel the heterogeneity in shape and intensity of the calcium response in T cell populations and especially in naive T cells, which display intracellular calcium oscillations upon stimulation by antigen presenting cells
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