Un derecho constitucional para las futuras generaciones. La otra forma del contrato social: el contrato generacional

Fil: Haberle, Peter. Universidad de Bayreuth. Centro de Investigaciones de Derecho Constitucional Europeo; Alemani

Mitochondrial ROS cause motor deficits induced by synaptic inactivity:implications for synapse pruning

Developmental synapse pruning refines burgeoning connectomes. The basic mechanisms of mitochondrial reactive oxygen species (ROS) production suggest they select inactive synapses for pruning: whether they do so is unknown. To begin to unravel whether mitochondrial ROS regulate pruning, we made the local consequences of neuromuscular junction (NMJ) pruning detectable as motor deficits by using disparate exogenous and endogenous models to induce synaptic inactivity en masse in developing Xenopus laevis tadpoles. We resolved whether: (1) synaptic inactivity increases mitochondrial ROS; and (2) antioxidants rescue synaptic inactivity induced motor deficits. Regardless of whether it was achieved with muscle (α-bugarotoxin), nerve (α-latrotoxin) targeted neurotoxins or an endogenous pruning cue (SPARC), synaptic inactivity increased mitochondrial ROS in vivo. The manganese porphyrins MnTE-2-PyP5+ and/or MnTnBuOE-2-PyP5+ blocked mitochondrial ROS to significantly reduce neurotoxin and endogenous pruning cue induced motor deficits. Selectively inducing mitochondrial ROS—using mitochondria-targeted Paraquat (MitoPQ)—recapitulated synaptic inactivity induced motor deficits; which were significantly reduced by blocking mitochondrial ROS with MnTnBuOE-2-PyP5+. We unveil mitochondrial ROS as synaptic activity sentinels that regulate the phenotypical consequences of forced synaptic inactivity at the NMJ. Our novel results are relevant to pruning because synaptic inactivity is one of its defining features

Background concentrations of mercury in Australian freshwater sediments: the role of catchment’s physico-chemical parameters on mercury deposition

Waterways in the Australian continent are facing increasing levels of mercury contamination due to industrialisation, agricultural intensification, energy production, urbanisation and mining. Mercury contamination undermines the use of waterways as a source of potable water and also has a deleterious effect on aquatic organisms. When developing management strategies to reduce mercury levels in waterways, it is crucial to set appropriate targets for mitigation of these contaminated waterways. These mitigation targets could be (1) trigger values or default guideline values provided by water and sediment quality guidelines or (2) background (pre-industrialisation) levels of mercury in the waterway. The aims of this study were to: (1) quantify the differences between existing environmental guideline values for mercury in aquatic systems, and background mercury concentrations, and (2) determine key factors affecting the spatial differences in background mercury concentrations in freshwater lake systems in Australia. Mercury concentrations were measured in background sediments from 21 lakes in Australia. Organic matter and precipitation were the main factors to explain mercury concentrations in sediments of lakes. These data indicate that background mercury concentrations in lake sediments can vary significantly across the continent, and the background concentrations are up to nine times lower than current sediment quality guidelines in Australia and New Zealand. This indicates that if waterway managers are aiming to restore systems to ‘pre-industrialisation’ mercury levels, it is highly important to quantify the site-specific background mercury concentration. We found that the geology of the lake catchment correlates to the background mercury concentration of lake sediments, with the highest mercury background levels being identified in lakes in igneous mafic intrusive regions and the lowest in areas underlain by regolith. Taking into account these findings, we provide a preliminary map of predicted background mercury sediment concentrations across Australia that could be used by waterway managers for determining management targets

Simulating the interannual variability of major dust storms on Mars using variable lifting thresholds

The redistribution of a finite amount of martian surface dust during global dust storms and in the intervening periods has been modelled in a dust lifting version of the UK Mars General Circulation Model. When using a constant, uniform threshold in the model’s wind stress lifting parameterisation and assuming an unlimited supply of surface dust, multiannual simulations displayed some variability in dust lifting activity from year to year, arising from internal variability manifested in surface wind stress, but dust storms were limited in size and formed within a relatively short seasonal window. Lifting thresholds were then allowed to vary at each model gridpoint, dependent on the rates of emission or deposition of dust. This enhanced interannual variability in dust storm magnitude and timing, such that model storms covered most of the observed ranges in size and initiation date within a single multiannual simulation. Peak storm magnitude in a given year was primarily determined by the availability of surface dust at a number of key sites in the southern hemisphere. The observed global dust storm (GDS) frequency of roughly one in every 3 years was approximately reproduced, but the model failed to generate these GDSs spontaneously in the southern hemisphere, where they have typically been observed to initiate. After several years of simulation, the surface threshold field—a proxy for net change in surface dust density—showed good qualitative agreement with the observed pattern of martian surface dust cover. The model produced a net northward cross-equatorial dust mass flux, which necessitated the addition of an artificial threshold decrease rate in order to allow the continued generation of dust storms over the course of a multiannual simulation. At standard model resolution, for the southward mass flux due to cross-equatorial flushing storms to offset the northward flux due to GDSs on a timescale of ∼3 years would require an increase in the former by a factor of 3–4. Results at higher model resolution and uncertainties in dust vertical profiles mean that quasi-periodic redistribution of dust on such a timescale nevertheless appears to be a plausible explanation for the observed GDS frequency

Racial Justice in Housing Finance: A Series on New Directions

The enclosed essays speak from a range of diverse viewpoints to explore how housing finance can be harnessed towards the ends of residential integration, equitable investment, and housing security, rather than purely for profit. Our authors offer ideas across a spectrum of proposed reforms. They describe how aspects of our current housing finance system derive from, or fail to correct for, our deep history of structural racism; they propose concrete steps toward re-engineering our current regulatory structure and housing programs to better advance equity, including addressing the particular harms of racial segregation; and they argue for expanded social housing and other visionary reforms

Archaeobotany in Australia and New Guinea: practice, potential and prospects

Archaeobotany is the study of plant remains from archaeological contexts. Despite Australasian research being at the forefront of several methodological innovations over the last three decades, archaebotany is now a relatively peripheral concern to most archaeological projects in Australia and New Guinea. In this paper, many practicing archaeobotanists working in these regions argue for a more central role for archaeobotany in standard archaeological practice. An overview of archaeobotanical techniques and applications is presented, the potential for archaeobotany to address key historical research questions is indicated, and initiatives designed to promote archaeobotany and improve current practices are outlined

Archaeobotany in Australia and New Guinea: practice, potential and prospects

Archaeobotany is the study of plant remains from archaeological contexts. Despite Australasian research being at the forefront of several methodological innovations over the last three decades, archaebotany is now a relatively peripheral concern to most archaeological projects in Australia and New Guinea. In this paper, many practicing archaeobotanists working in these regions argue for a more central role for archaeobotany in standard archaeological practice. An overview of archaeobotanical techniques and applications is presented, the potential for archaeobotany to address key historical research questions is indicated, and initiatives designed to promote archaeobotany and improve current practices are outlined

Rapid global ocean-atmosphere response to Southern Ocean freshening during the last glacial

This is the final version of the article. Available from Springer Nature via the DOI in this record.Contrasting Greenland and Antarctic temperatures during the last glacial period (115,000 to 11,650 years ago) are thought to have been driven by imbalances in the rates of formation of North Atlantic and Antarctic Deep Water (the 'bipolar seesaw'). Here we exploit a bidecadally resolved (14)C data set obtained from New Zealand kauri (Agathis australis) to undertake high-precision alignment of key climate data sets spanning iceberg-rafted debris event Heinrich 3 and Greenland Interstadial (GI) 5.1 in the North Atlantic (~30,400 to 28,400 years ago). We observe no divergence between the kauri and Atlantic marine sediment (14)C data sets, implying limited changes in deep water formation. However, a Southern Ocean (Atlantic-sector) iceberg rafted debris event appears to have occurred synchronously with GI-5.1 warming and decreased precipitation over the western equatorial Pacific and Atlantic. An ensemble of transient meltwater simulations shows that Antarctic-sourced salinity anomalies can generate climate changes that are propagated globally via an atmospheric Rossby wave train.A challenge for testing mechanisms of past climate change is the precise correlation of palaeoclimate records. Here, through climate modelling and the alignment of terrestrial, ice and marine (14)C and (10)Be records, the authors show that Southern Ocean freshwater hosing can trigger global change.This work was funded by the Australian Research Council (FL100100195, DP170104665 and SR140300001) and the Natural Environment Research Council (NE/H009922/1 and NE/H007865/1)

A Lorenz/Boer energy budget for the atmosphere of Mars from a “reanalysis” of spacecraft observations

We calculate a Lorenz energy budget for the Martian atmosphere from reanalysis derived from Mars Global Surveyor data for Mars years 24–27. We present global, annual mean energy and conversion rates per unit area and per unit mass and compare these to Earth data. The directions of the energy conversion terms for Mars are similar to Earth, with the exception of the barotropic conversion between zonal and eddy kinetic energy reservoirs. Further, seasonal and hemispheric decomposition reveals a strong conversion between zonal energy reservoirs over the year, but these balance each other out in global and annual mean. On separating the diurnal timescale, the contribution to the conversion terms and eddy kinetic energy for diurnal and shorter timescales in many cases (especially during planet-encircling dust storms) exceeds the contribution of longer timescales. This suggests that thermal tides have a significant effect on the generation of eddy kinetic energy

The solsticial pause on Mars: 1. A planetary wave reanalysis

Large-scale planetary waves are diagnosed from an analysis of profiles retrieved from the Thermal Emission Spectrometer aboard the Mars Global Surveyor spacecraft during its scientific mapping phase. The analysis is conducted by assimilating thermal profiles and total dust opacity retrievals into a Mars global circulation model. Transient waves are largest throughout the northern hemisphere autumn, winter and spring period and almost absent during the summer. The southern hemisphere exhibits generally weaker transient wave behaviour. A striking feature of the low-altitude transient waves in the analysis is that they show a broad subsidiary minimum in amplitude centred on the winter solstice, a period when the thermal contrast between the summer hemisphere and the winter pole is strongest and baroclinic wave activity might be expected to be strong. This behaviour, here called the ‘solsticial pause,’ is present in every year of the analysis. This strong pause is under-represented in many independent model experiments, which tend to produce relatively uniform baroclinic wave activity throughout the winter. This paper documents and diagnoses the transient wave solsticial pause found in the analysis; a companion paper investigates the origin of the phenomenon in a series of model experiments