Monuments on the horizon

Barrows, as burial markers, are ubiquitous throughout North-Western Europe. In some regions dense concentrations of monuments form peculiar configurations such as long alignments while in others they are spread out extensively, dotting vast areas with hundreds of mounds. These vast barrow landscapes came about through thousands of years of additions by several successive prehistoric and historic communities. Yet little is known about how these landscapes developed and came about. That is what this research set out to do. By unravelling the histories of specific barrow landscapes in the Low Countries, several distinct activity phases of intense barrow construction could be recognised. Each of these phases contributed in a particular fashion to how the barrow landscape developed and reveals shifting attitudes to these landscape monuments. By creating new monuments in a specific place and in a particular fashion, prehistoric communities purposefully transformed the form and shape of the barrow landscape. Using several GIS-techniques such as a skyline-analysis, this research was able to demonstrate how each barrow then took up a specific (and different) position within such a social landscape. While the majority of the barrows were only visible from relatively close by, specific monuments took up a dominating position, cresting the horizon, and they were visible from much further away. It was argued that these burial mounds remained important landscape monuments on the purple heathlands. They continued to attract attention, and by their visibility ensured to endure in the collective memory of the communities shaping themselves around these monuments

Field systems and later prehistoric land use:New insights into land use detectability and palaeodemography in the Netherlands through LiDAR, automatic detection and traditional field data

This paper discusses how the use of AI (artificial intelligence) detected later prehistoric field systems provides a more reliable base for reconstructing palaeodemographic trends, using the Netherlands as a case study. Despite its long tradition of settlement excavations, models that could be used to reconstruct (changes in) prehistoric land use have been few and often relied on (insufficiently mapped) nodal data points such as settlements and barrows. We argue that prehistoric field systems of field plots beset on all sides by earthen banks—known as Celtic fields—are a more suitable (i.e. less nodal) proxy for reconstructing later prehistoric land use.For four 32.25 km2 case study areas in different geogenetic regions of the Netherlands, prehistoric land use surface areas are modelled based on conventional methods and the results are compared to the results we obtained by using AI-assisted detection of prehistoric field systems. The nationally available LiDAR data were used for automated detection. Geotiff DTM images were fed into an object detection algorithm (based on the YOLOv4 framework and trained with known Dutch sites), and resultant geospatial vectors were imported into GIS.Our analysis shows that AI-assisted detection of prehistoric embanked field systems on average leads to a factor 1.84 increase in known surface areas of Celtic fields. Modelling the numbers of occupants from this spatial coverage, yields population sizes of 37–135 persons for the case study regions (i.e. 1.15 to 4.19 p/km2). This range aligns well with previous estimates and offers a more robust and representative proxy for palaeodemographic reconstructions. Variations in land use coverage between the regions could be explained by differences in present-day land use and research intensity. Particularly the regionally different extent of forestlands and heathlands (ideal for the (a) preservation and (b) automated LiDAR detection of embanked field systems) explains minor variations between the four case study regions

Doc2 Proteins Are Not Required for the Increased Spontaneous Release Rate in Synaptotagmin-1-Deficient Neurons

Regulated secretion is controlled by Ca 2+ sensors with different affinities and subcellular distributions. Inactivation of Syt1 (synaptotagmin-1), the main Ca 2+ sensor for synchronous neurotransmission in many neurons, enhances asynchronous and spontaneous release rates, suggesting that Syt1 inhibits other sensors with higher Ca 2+ affinities and/or lower cooperativities. Such sensors could include Doc2a and Doc2b, which have been implicated in spontaneous and asynchronous neurotransmitter release and compete with Syt1 for binding SNARE complexes. Here, we tested this hypothesis using triple-knock-out mice. Inactivation of Doc2a and Doc2b in Syt1-deficient neurons did not reduce the high spontaneous release rate. Overexpression of Doc2b variants in triple-knock-out neurons reduced spontaneous release but did not rescue synchronous release. A chimeric construct in which the C2AB domain of Syt1 was substituted by that of Doc2b did not support synchronous release either. Conversely, the soluble C2AB domain of Syt1 did not affect spontaneous release. We conclude that the high spontaneous release rate in synaptotagmin-deficient neurons does not involve the binding of Doc2 proteins to Syt1 binding sites in the SNARE complex. Instead, our results suggest that the C2AB domains of Syt1 and Doc2b specifically support synchronous and spontaneous release by separate mechanisms. (Both male and female neurons were studied without sex determination)

Experiment collaboration program during a Martian analogue mission to introduce young students to human space exploration

The last decade has demonstrated an increased public and private interest towards crewed missions through the emergence of New Space and the Artemis program. There is therefore a need to form the next generation of scientists to prepare future crewed space exploration missions. In this context, it is important to familiarize teenagers with the scientific issues of today’s world and to inspire them to engage in the space sector. Crew 263 is a group of seven students preparing a Martian analogue mission at the Mars Desert Research Station (MDRS) in the desert of Utah (United States). A Martian analogue mission at the MDRS, because is the perfect set-up to introduce young students to human space exploration. In the context of their mission, Crew 263 has organized a program of space educational activities for middle and high school students surrounding the topics of altered gravity, astronomy, health and safety procedures and robotic systems. Precisely, a set of four experiments that will be performed by the students was conceived to bring into light the various scientific topics surrounding space exploration missions. The experiment “Plants in Microgravity” aims to illustrate the influence of gravity on plant growth by planting seeds in pots mounted on a rotating platform in a vertical plane, which will disturb their gravitational cues. “Beginner Astronomer” aims to introduce students to astronomy and astrophotography by establishing with the students a list of galaxies/nebulas to be observed during the Mission. Then, for “Emergency situation at the MDRS” students will put into practice the scientific approach by creating protocols to mitigate risk situations during space exploration missions. Finally, for the “Perseverance’s little brother” experiment, students will develop a small rover to analyze the atmosphere condition around the MDRS station. To maximize their involvement, prior to the mission at the MDRS, the middle and high school students prepare the experiments with the support of the crew. Then, the prepared experiment will be performed in parallel with the crew while they are simulating Martian life. To allow students to be immersed in the mission when the crew will be at the MDRS, short podcasts will be recorded describing the crew’s daily life and the evolution of the different experiments. This podcast will be sent to the classes during the simulation, thus allowing the students to have an insight on the daily life of the analogue astronauts at the station

The rhesus protein RhCG: a new perspective in ammonium transport and distal urinary acidification

Urinary acidification is a complex process requiring the coordinated action of enzymes and transport proteins and resulting in the removal of acid and the regeneration of bicarbonate. Proton secretion is mediated by luminal H(+)-ATPases and requires the parallel movement of NH(3), and its protonation to NH(4)(+), to provide sufficient buffering. It has been long assumed that ammonia secretion is a passive process occurring by means of simple diffusion driven by the urinary trapping of ammonium. However, new data indicate that mammalian cells possess specific membrane proteins from the family of rhesus proteins involved in ammonia/μm permeability. Rhesus proteins were first identified in yeast and later also in plants, algae, and mammals. In rodents, RhBG and RhCG are expressed in the collecting duct, whereas in humans only RhCG was detected. Their expression increases with maturation of the kidney and accelerates after birth in parallel with other acid-base transport proteins. Deletion of RhBG in mice had no effect on renal ammonium excretion, whereas RhCG deficiency reduces renal ammonium secretion strongly, causes metabolic acidosis in acid-challenged mice, and impairs restoration of normal acid-base status. Microperfusion experiments or functional reconstitution in liposomes demonstrates that ammonia is the most likely substrate of RhCG. Similarly, crystal structures of human RhCG and the homologous bacterial AmtB protein suggest that these proteins may form gas channels.Kidney International advance online publication, 6 October 2010; doi:10.1038/ki.2010.386

Genes but Not Genomes Reveal Bacterial Domestication of Lactococcus Lactis

BACKGROUND: The population structure and diversity of Lactococcus lactis subsp. lactis, a major industrial bacterium involved in milk fermentation, was determined at both gene and genome level. Seventy-six lactococcal isolates of various origins were studied by different genotyping methods and thirty-six strains displaying unique macrorestriction fingerprints were analyzed by a new multilocus sequence typing (MLST) scheme. This gene-based analysis was compared to genomic characteristics determined by pulsed-field gel electrophoresis (PFGE). METHODOLOGY/PRINCIPAL FINDINGS: The MLST analysis revealed that L. lactis subsp. lactis is essentially clonal with infrequent intra- and intergenic recombination; also, despite its taxonomical classification as a subspecies, it displays a genetic diversity as substantial as that within several other bacterial species. Genome-based analysis revealed a genome size variability of 20%, a value typical of bacteria inhabiting different ecological niches, and that suggests a large pan-genome for this subspecies. However, the genomic characteristics (macrorestriction pattern, genome or chromosome size, plasmid content) did not correlate to the MLST-based phylogeny, with strains from the same sequence type (ST) differing by up to 230 kb in genome size. CONCLUSION/SIGNIFICANCE: The gene-based phylogeny was not fully consistent with the traditional classification into dairy and non-dairy strains but supported a new classification based on ecological separation between "environmental" strains, the main contributors to the genetic diversity within the subspecies, and "domesticated" strains, subject to recent genetic bottlenecks. Comparison between gene- and genome-based analyses revealed little relationship between core and dispensable genome phylogenies, indicating that clonal diversification and phenotypic variability of the "domesticated" strains essentially arose through substantial genomic flux within the dispensable genome

Aerosol Transport and Distribution:A Global Modeling Study Constrained by Remote Sensing Observations

The fourth report of the Intergovernmental Panel of Climate Change (IPCC) unambiguously indicates that the climate is changing. Climate change is induced by changes in atmospheric abundances of greenhouse gases and aerosols, solar radiation and land surface properties, which all alter the radiative balance of the Earth. Among them, greenhouse gases and aerosols are likely the compounds affecting the climate the most. While greenhouse gases warm the Earth, aerosols influence its radiative balance by scattering and absorbing solar radiation (the direct effect), and by modifying cloud amount and properties (the indirect effect). The radiative forcing of aerosols on the climate is however the less understood among the various forcings currently considered in the IPCC assessment. This is likely related to the lack of comprehensive and accurate observations of aerosols (and in particular of their vertical distribution) which thus makes global aerosol models difficult to constrain. Recent model intercomparisons have indicated that different assumptions regarding aerosol emissions, formation and growing properties, and removal processes generate large diversities within models. These large diversities are found in particular in the Arctic and the upper troposphere region where extreme surrounding conditions take place, limiting instrument sensitivity and accuracy. The objectives of this thesis are to better quantify the processes driving the aerosol distribution in regions where the uncertainties are the largest, including the Arctic region and the upper troposphere, and to assess the quality of CALIOP observations. For this purpose, we used the fully coupled global climate-aerosol-chemistry ECHAM5-HAMMOZ model conjointly with a suite of remote sensing observations including the CALIOP satellite instrument, which provides the vertical distribution of aerosols. The model predicts the size distribution and composition of aerosols as well as the number concentration of cloud droplets and ice crystals. We first investigated the processes that drive the transport of soluble and insoluble compounds toward the Arctic in the ECHAM5-HAMMOZ model. Recognizing that scavenging processes may be an issue in global models, we "re-visited" their properties in ECHAM5-HAMMOZ. We find that the model better reproduces the aerosol vertical distribution in the northern mid- and high-latitudes, especially in the free troposphere, by decreasing aerosol scavenging coefficients in the model. Using smaller aerosol scavenging coefficients results in an increase of aerosol burden and lifetime, especially in the Arctic. In addition, the Arctic haze phenomenon is better represented in the simulation using decreased aerosol scavenging coefficients. The relative contributions of different processes governing the transport of aerosols from the midlatitudes toward the Arctic together with the relative contributions of different geopolitical source regions were then quantified. We find that Europe and Siberia contribute the most to the Arctic pollution even though Asian anthropogenic emissions are much larger. The model suggests that BC emitted in Siberia and Europe is ten times more efficiently deposited onto the Arctic than BC emitted in Asia. We next investigated an aerosol layer that forms in the vicinity of the tropical tropopause layer (TTL) over the southern Asian and Indian Ocean region. Aerosols in this layer are observed with the CALIOP instrument even though ice clouds partly mask their signal. The aerosol layer follows the Inter Tropical Convergence Zone (ITCZ), which indicates that these aerosols are likely transported during convective processes. The ECHAM5.5-HAM2 model reproduces such an aerosol layer in the TTL over the same region but clearly overestimates CALIOP data. Model results suggest that aerosols in this layer are mostly sulfate particles transported during convective processes and originating from natural sources. The shortwave forcing of this aerosol layer is estimated. Finally, we assessed the accuracy of aerosol extinction retrievals from the CALIOP satellite instrument by comparing them with remote sensing observations such as AERONET, MODIS and MISR over the last four years. Overall, standard CALIOP products underestimate by 50% observed aerosol extinctions. However, this comparison is substantially improved by screening CALIOP data. The comparison of the CALIOP screened product with the ECHAM5.5-HAM2 model shows large disparities in model results. The model reproduces quite well the observed interannual variability and vertical distribution of aerosols in Europe and North Africa while it underestimates them in America and Asia. This is likely due to an underestimate of dust and anthropogenic emissions in North America and Asia

Pollution transport efficiency toward the Arctic: Sensitivity to aerosol scavenging and source regions

The processes driving current changes in Arctic atmospheric composition and climate are still uncertain. In particular the relative contributions of major source regions from the midlatitudes remain a matter of debate in the literature. The objectives of this study are to better quantify the relative contributions of different processes governing the transport of pollution from the midlatitudes to the Arctic and the relative contributions of different geopolitical source regions. We use a suite of observational data sets (including the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaigns and the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite instrument) to constrain a global aerosol simulation from the ECHAM5-HAMMOZ model. Preliminary comparison of model results with vertical profiles of sulfate and black carbon (BC) collected during the ARCTAS campaigns and with aerosol extinction time series retrieved from CALIOP indicates that the model underestimates export of aerosols from the planetary boundary layer to the free troposphere in the midlatitudes and long-range transport of aerosols from the midlatitudes toward the Arctic. In contrast, observed CO profiles are relatively well simulated, which points to a possible problem with wet scavenging. Decreasing the prescribed aerosol scavenging coefficients within the range of experimental data available in the literature significantly improves the agreement with observations. Sulfate and BC burdens in the Arctic increase by a factor 5-6. Annual global lifetimes of sulfate and BC increase from 3.1 to 4.6 days and from 4.4 to 5.9 days, respectively. Using the improved simulation, we find that 59% of sulfate in the Arctic troposphere comes from the oxidation of SO2 emitted in Siberia (19%), Europe (18%), Asia (13%), and North America (9%). Anthropogenic and biomass burning BC emitted in Siberia, Asia, Europe, and North America contributes 29, 27, 25, and 17%, respectively, to the Arctic BC burden. Emissions of aerosols (or precursors) from Siberia and Europe are more susceptible to be transported and subsequently deposited on the Arctic (about 7-12%) compared to those from North America and Asia (1-4%). Overall, the study shows that aerosol scavenging removal processes play a crucial role on the aerosol transport from the midlatitudes toward the Arctic and should be carefully characterized in aerosol models

Aspects éthiques et juridiques des plantes invasives

Ethical and legal issues of invasive plants: In this article, we first present the theoretical field of plant ethics, which has developed mainly in the last thirty years. We then study the case of invasive plants and the criteria used to define them in the scientific community. We then ask what legal measures apply to these plants and what is their history. Finally, we ask whether the way invasive plants are treated from the perspective of conservation biology and the resulting legal perspective is compatible with the concept of creature dignity. The working hypothesis of this article is that the concept of invasive species is too broad. This can lead to a form of expedient ethics and justice. We therefore argue that invasive plants should be given a fair trial so that their dignity is respected.Dans cet article, nous présentons d’abord le champ théorique de l’éthique du végétal qui s’est surtout développé depuis une trentaine d’années. Nous étudions ensuite le cas des plantes invasives et les critères utilisés pour les définir dans la communauté scientifique. Nous nous demandons ensuite quelles sont les mesures légales qui s’appliquent à ces plantes et quel est leur histoire. Enfin, nous nous demandons si la façon dont les plantes invasives sont traitées du point de vue de la biologie de la conservation et du point de vue légal qui en découle est compatible avec le concept de dignité de la créature. L’hypothèse de travail de cet article est que le concept d’espèce invasive est trop large. Ceci peut conduire à une forme d’éthique et de justice expéditive. Nous défendons en conséquence que les plantes invasives devraient bénéficier d’un juste procès pour que leur dignité soit respectée