Gridmapping the northern plains of Mars: Geomorphological, Radar and Water-Equivalent Hydrogen results from Arcadia Plantia

A project of mapping ice-related landforms was undertaken to understand the role of sub-surface ice in the northern plains. This work is the first continuous regional mapping from CTX (“ConTeXt Camera”, 6 m/pixel; Malin et al., 2007) imagery in Arcadia Planitia along a strip 300 km across stretching from 30°N to 80°N centred on the 170° West line of longitude. The distribution and morphotypes of these landforms were used to understand the permafrost cryolithology. The mantled and textured signatures occur almost ubiquitously between 35° N and 78° N and have a positive spatial correlation with inferred ice stability based on thermal modelling, neutron spectroscopy and radar data. The degradational features into the LDM (Latitude Dependent Mantle) include pits, scallops and 100 m polygons and provide supporting evidence for sub-surface ice and volatile loss between 35-70° N in Arcadia with the mantle between 70-78° N appearing much more intact. Pitted terrain appears to be much more pervasive in Arcadia than in Acidalia and Utopia suggesting that the Arcadia study area had more wide-spread near-surface sub-surface ice, and thus was more susceptible to pitting, or that the ice was less well-buried by sediments. Correlations with ice stability models suggest that lack of pits north of 65-70° N could indicate a relatively young age (~1Ma), however this could also be explained through regional variations in degradation rates. The deposition of the LDM is consistent with an airfall hypothesis however there appears to be substantial evidence for fluvial processes in southern Arcadia with older, underlying processes being equally dominant with the LDM and degradation thereof in shaping the landscape

Standardizing the nomenclature of Martian impact crater ejecta morphologies

International audienceThe Mars Crater Morphology Consortium recommends the use of a standardized nomenclature system when discussing Martian impact crater ejecta morphologies. The system utilizes nongenetic descriptors to identify the various ejecta morphologies seen on Mars. This system is designed to facilitate communication and collaboration between researchers. Crater morphology databases will be archived through the U.S. Geological Survey in Flagstaff, where a comprehensive catalog of Martian crater morphologic information will be maintained

PRIVATIZED FROM THE INSIDE: A NETWORK ETHNOGRAPHY OF BRAZILIAN TEACHER EDUCATION POLICY UNDER THE WORKERS’ PARTY

The theory of a globally structured education agenda interrogates the political and economic systems that influence how states take on policy ideas. One way that globalizing processes may take place is through network governance, or via networks of people, ideas, researchers, governments, non-governmental organizations, private companies, etc. This study explores how power plays a role in the proliferation of particular policy ideas about teacher education in such networks. Brazilian education expanded greatly since the 1990s as did the demand for teachers of higher qualifications. Via network ethnography, this study examined the people, organizations, and ideas that influenced teacher education policy since the mid-1990s. Network ethnography is an emerging method and framework in international education research, and this study builds on what is understood about the role of corporations and other private enterprises in education policy. The results of this network ethnography revealed two primary coalitions, each of whose power over teacher education policy shifted with federal regime changes. One coalition, centered around the Brazilian Campaign for the Right to Education, frames teacher training and schooling as places to foster participatory democracy and build citizens. The other coalition, centered around the All for Education Movement, frames teacher training as a set of apolitical technical skills that should be provided in so-called proven and fiscally efficient ways. In light of these results, I argue that the dominant coalition, led by the All for Education Movement, which is backed by the business and financial sectors, steadily and consistently worked to solidify its place in the federal education policymaking arena throughout the time period under study and as a result governs teacher qualification and teacher training issues

Standardizing the nomenclature of Martian impact crater ejecta morphologies

The Mars Crater Morphology Consortium recommends the use of a standardized nomenclature system when discussing Martian impact crater ejecta morphologies seen on Mars. The system utilizes nongenetic descriptors to identify the various ejecta morphologies seen on Mars. This system is designed to facilitate communication and collaboration between researchers. Crater morphology databases will be archived through the U.S. Geological Survey in Flagstaff, where a comprehensive catalog of Martian crater morphologic information will be maintained

Late Tharsis formation and implications for early Mars

The Tharsis region is the largest volcanic complex on Mars and in the Solar System. Young lava flows cover its surface (from the Amazonian period, less than 3 billion years ago) but its growth started during the Noachian era (more than 3.7 billion years ago). Its position has induced a reorientation of the planet with respect to its spin axis (true polar wander, TPW), which is responsible for the present equatorial position of the volcanic province. It has been suggested that the Tharsis load on the lithosphere influenced the orientation of the Noachian/Early Hesperian (more than 3.5 billion years ago) valley networks(1) and therefore that most of the topography of Tharsis was completed before fluvial incision. Here we calculate the rotational figure of Mars (that is, its equilibrium shape) and its surface topography before Tharsis formed, when the spin axis of the planet was controlled by the difference in elevation between the northern and southern hemispheres (hemispheric dichotomy). We show that the observed directions of valley networks are also consistent with topographic gradients in this configuration and thus do not require the presence of the Tharsis load. Furthermore, the distribution of the valleys along a small circle tilted with respect to the equator is found to correspond to a southern-hemisphere latitudinal band in the pre-TPW geographical frame. Preferential accumulation of ice or water in a south tropical band is predicted by climate model simulations of early Mars applied to the pre-TPW topography. A late growth of Tharsis, contemporaneous with valley incision, has several implications for the early geological history of Mars, including the existence of glacial environments near the locations of the pre-TPW poles of rotation, and a possible link between volcanic outgassing from Tharsis and the stability of liquid water at the surface of Mars

Grid Mapping the Northern Plains of Mars: Using Morphotype and Distribution of Ice‐Related Landforms to Understand Multiple Ice‐Rich Deposits in Utopia Planitia

This work in Utopia Planitia is the first continuous regional mapping of ice‐related landforms integrated into an effort to study the three main basins (Arcadia, Acidalia, and Utopia Planitiae) in the northern plains. The distribution and morphotypes of these landforms, SHAllow RADar detections, and crater size‐frequency distribution measurements (>50 m in diameter) were used to understand the permafrost cryolithology and its past evolution in relation to climate in Utopia Planitia. Three assemblages of landforms were identified based on their spatial correlation and correlation with Mars Orbiter Laser Altimeter surface roughness along a strip from 30°N to 80°N. At 30°–38°N, the assemblage is formed by kilometer‐scale polygons, high‐albedo mounds, and thumbprint terrains. This assemblage is associated with a lobate deposit of 30 m in thickness with a crater retention age of 1 Ga. At 38°–47°N, the assemblage is comprised of large scallops, 100‐m‐diameter polygons, pits, and mantled deposits. This assemblage is correlated with a deposit of 80 m in thickness containing excess ice (~50–85% by volume) with a crater retention age of about 10 Ma. At 47°–78°N, the assemblage is composed of mantled deposits, textured terrains, and 30‐m‐diameter polygons. This assemblage is related to the ice‐rich, debris‐covered, latitude‐dependent mantle that has a crater retention age of about 1.5 Ma. Utopia Planitia appears to be a region of combined depositions of sediment and continuous cold climatic conditions that leaded to a complex distribution of ground ice

Grid Mapping the Northern Plains of Mars: A New Overview of Recent Water‐ and Ice‐Related Landforms in Acidalia Planitia

We used a grid‐mapping technique to analyze the distribution of 13 water‐ and ice‐related landforms in Acidalia Planitia as part of a joint effort to study the three main basins in the northern lowlands of Mars, that is, Acidalia, Utopia, and Arcadia Planitiae. The landforms were mapped at full Context Camera resolution along a 300‐km‐wide strip from 20°N to 84°N. We identified four landform assemblages: (1) Geologically recent polar cap (massive ice), which superposes the latitude‐dependent mantle (LDM) (LA1); (2) ice‐related landforms, such as LDM, textured terrain, small‐scale polygons, scalloped terrain, large‐scale viscous flow features, and gullies, which have an overlapping distribution (LA2); (3) surface features possibly related to water and subsurface sediment mobilization (LA3; kilometer‐scale polygons, large pitted mounds, small pitted mounds, thumbprint terrain); and (4) irregularly shaped pits with raised rims on equator‐facing slopes. Pits are likely the result of an energetic release of volatiles (H2O, CO2, and CH4), rather than impact‐, volcanism‐, or wind‐related processes. LDM occurs ubiquitously from 44°N to 78°N in Acidalia Planitia. Various observations suggest an origin of air fall deposition of LDM, which contains less ice in the uppermost tens of meters in Acidalia Planitia than in Arcadia and Utopia Planitiae. However, LDM may be thicker and more extended in the past in Acidalia Planitia. The transition between LDM‐free terrain and LDM is situated further north than in Utopia and Arcadia Planitiae, suggesting different past and/or present climatic conditions among the main basins in the northern lowlands

African swine fever: how can global spread be prevented?

African swine fever (ASF) is a devastating haemorrhagic fever of pigs with mortality rates approaching 100 per cent. It causes major economic losses, threatens food security and limits pig production in affected countries. ASF is caused by a large DNA virus, African swine fever virus (ASFV). There is no vaccine against ASFV and this limits the options for disease control. ASF has been confined mainly to sub-Saharan Africa, where it is maintained in a sylvatic cycle and/or among domestic pigs. Wildlife hosts include wild suids and arthropod vectors. The relatively small numbers of incursions to other continents have proven to be very difficult to eradicate. Thus, ASF remained endemic in the Iberian peninsula until the mid-1990s following its introductions in 1957 and 1960 and the disease has remained endemic in Sardinia since its introduction in 1982. ASF has continued to spread within Africa to previously uninfected countries, including recently the Indian Ocean islands of Madagascar and Mauritius. Given the continued occurrence of ASF in sub-Saharan Africa and increasing global movements of people and products, it is not surprising that further transcontinental transmission has occurred. The introduction of ASF to Georgia in the Caucasus in 2007 and dissemination to neighbouring countries emphasizes the global threat posed by ASF and further increases the risks to other countries