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A new genus and species of the Elcanidae (Orthoptera, Elcanoidea), Cascadelcana virginiana n. gen. n. sp., is described based on a forewing specimen from the Upper Triassic (Norian) Cow Branch Formation in the Solite Quarry Lagerstätte near the North Carolina-Virginia boundary, USA. It is distinguished from other elcanid species by its RP+MA1 with six branches, M with two branches before stem MA1 fused with RP, and short CuA almost vertical against the posterior margin. This fossil represents the earliest definitive record of the family Elcanidae and the first orthopteran described from the Triassic of North America. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) analyses show that the veins and a pterostigma-like structure on the wing of C. virginiana n. gen. n. sp. are preserved as carbonaceous compressions. The presence of a pterostigma-like structure in elcanids indicates that they may have evolved a particular flight mechanism distinct from those of other orthopterans.
We analysed the supportive social networks associated with the conservation of six threatened Australian bird taxa, in one of the first network analyses of threatened species conservation programmes. Each example showed contrasting vulnerabilities. The Alligator Rivers yellow chat Epthianura crocea tunneyi had the smallest social network and no real action was supported. For the Capricorn yellow chat Epthianura crocea macgregori the network was centred on one knowledgeable and committed actor. The orange-bellied parrot Neophema chrysogaster had a strongly connected recovery team but gaps in the overall network could limit communication. The recovery teams for the swift parrot Lathamus discolor and Baudin's black-cockatoo Calyptorhynchus baudinii had strong links among most stakeholders but had weak ties to the timber industry and orchardists, respectively, limiting their capacity to manage threatening processes. Carnaby's black cockatoo Calyptorhynchus latirostris seemed to have the most effective social network of any of the taxa studied but may be vulnerable to skill shortages. In each case the network analysis pointed to gaps that could be filled to enhance the conservation effort, and highlighted the importance of recovery teams. The research suggests that formal network analysis could assist in the design of more effective support mechanisms for the conservation of threatened species.
We have applied mechanical exfoliation for the preparation of ultra-thin samples of the phyllosilicate mineral biotite. We demonstrate that the 'scotch tape' approach, which was made famous as an early method for production of single-atom-thick graphene, can be used for production of sheet-silicate specimens that are sufficiently thin to allow high-resolution transmission electron microscope (HRTEM) imaging to be achieved successfully while also being free from the specimen preparation artefacts that are often caused by ion-beam milling techniques. Exfoliation of the biotite parallel to the (001) planes has produced layers as thin as two structural TOT units thick (∼2 nm). The minimal specimen thickness enabled not only HRTEM imaging but also the application of subsequent exit wavefunction restoration to reveal the pristine biotite lattice. Exit wavefunction restoration recovers the full complex electron wave from a focal series of HRTEM images, removing the effects of coherent lens aberrations. This combination of methods therefore produces images in which the observed features are readily interpreted to obtain atomic resolution structural information.
The early climate of Mars (Noachian Period, the first ~20% of its history) is thought to differ significantly from that of its more recent history (Amazonian Period, the last ~66%) which is characterized by hyperarid, hypothermal conditions that result in mean annual air temperatures (MAAT) well below 0°C, a global cryosphere, minimal melting on the ground surface, and a horizontally stratified hydrologic system. We explore the nature of the fluvial and lacustrine environments in the Mars-like hyperarid, hypothermal McMurdo Dry Valleys (MDV), where the MAAT is well below 0°C (~ -14 to -30°C) in order to assess whether the Late Noachian geologic record can be explained by a climate characterized by “cold and icy” conditions. We find that the MDV hydrological system and cycle provide important insights into the potential configuration of a “cold and icy” early Mars climate in which MDV-like ephemeral streams and rivers, and both closed-basin and open-basin lakes could form. We review a series of MDV fluvial and lacustrine features to guide investigators in the analysis of the geomorphology of early Mars and we outline a new model for the nature and evolution of a “cold and icy” Late Noachian climate based on these observations. We conclude that a cold and icy Late Noachian Mars with MAAT below freezing, but peak seasonal and peak daily temperatures above 0°C, could plausibly account for the array of Noachian-aged fluvial and lacustrine features observed on Mars. Our assessment also provides insight into the potential effects of punctuated warming on a cold and icy early Mars, in which impact crater formation or massive volcanic eruptions cause temperatures in the melting range for decadal to centennial timescales. We outline a set of outstanding questions and tests concerning the nature and evolution of these features on Mars.
This chapter reviews basic physical processes controlling interactions between silicate magmas and surface ice and snow layers, focusing on subglacial, englacial, and supraglacial interactions. Where possible, theoretical considerations are linked with observations of the lithofacies and sequence characteristics of the deposits expected as a result of these various interactions, with particular focus on the products of mafic eruptions. The range of possible interactions is large, resulting in a correspondingly diverse group of resulting landforms. These predictions are made for the environment of the Earth, but with suitable changes to atmospheric temperature and pressure and acceleration due to gravity are readily applicable on Mars. Numerous putative examples of volcano–ice interaction features on Mars have already been documented and this chapter provides a comprehensive unifying theoretical framework for further interpretation of features on both planets.
Magma–ice interactions can occur in a number of ways and can produce a range of products and landforms (e.g., Lescinsky and Fink, 2000; Mee et al., 2006; Komatsu et al., 2007; Larsen and Eiriksson, 2008; Smellie, 2009), the details depending on the geometry and timescale of the interaction. No subglacial rhyolite eruptions have ever been observed. A “typical” mafic volcanic eruption progresses from initial rapid subsidence and collapse of the overlying ice surface to form a pit, simultaneous with subglacial emplacement of volcanic products (often but not always pillow lava, forming a pillow mound or ridge) in a water-filled cavity. Many eruptions might cease at this point but, commonly, as the volcanic edifice grows upward and the vent becomes shallower, the magma interacts explosively with the surrounding meltwater and a high subaerial eruption column is generated, accompanied by deposition of abundant ash. This results in the construction of a subaqueous tuff cone or ridge, the latter known as a tindar (Jones, 1969).
The McMurdo Dry Valleys (MDV), classified as a hyperarid, cold-polar desert, have long been considered an important terrestrial analog for Mars because of their cold and dry climate and their suite of landforms that closely resemble those occurring on the surface of Mars at several different scales, despite significant differences in current atmospheric pressure. The MDV have been subdivided on the basis of summertime measurements of atmospheric temperature, soil moisture, and relative humidity, into three microclimate zones (Marchant and Head,2007): a coastal thaw zone, an inland mixed zone, and a stable upland zone. Minor differences in these climate parameters lead to large differences in the distribution and morphology of features at the macroscale (e.g., slopes and gullies); mesoscale (e.g., polygons, viscous-flow features, and debris-covered glaciers); and microscale (e.g., rock-weathering processes/features, including wind erosion, salt weathering, and surface pitting). Equilibrium landforms form in balance with environmental conditions within fixed microclimate zones. For example, sublimation polygons indicate the presence of extensive near-surface ice in the MDV and identification of similar landforms on Mars appears to provide a basis for detecting the location of current and past shallow ice. The modes of occurrence of the limited and unusual biota in the MDV provide terrestrial laboratories for the study of possible environments for life on Mars. The range of microenvironments in the MDV are hypersensitive to climate variability, and their stability and change provide important indications of climate history and potential stress on the biota.
A microneutralization test for serotyping of FMD viruses is described. It is based on earlier observations by Booth, Rweyemamu & Pay (1978) that dose-response relationships in quantal microneutralizations often deviated from linearity. The typing test described therefore utilizes undiluted virus preparations. In about 90% of samples a positive typing was obtained in contrast with about 50% for the complement fixation test. The test was also found to be susceptible to minimal quantities of heterotypic viral contamination.
For strain differentiation the microneutralization test was carried out as a checkerboard test. When compared with the complement fixation test it was found to be more specific. The necessity to utilize virus-neutralization test systems for comparing (FMD) virus strains particularly for the purpose of vaccine selection is emphasized. The two dimensional microneutralization test has been applied to a study of comparing FMDV vaccine strains for Europe, South America, the Middle East and East Africa.
Thermal contraction crack polygons modify the generation, transport, and storage of water in Wright Valley gullies. Water generation is contributed to by trapping of windblown snow in polygon troughs. Water transport is modified by changes to the ice-cement table and active layer topography caused by polygon trough formation. Water storage is modified by sediment grain-size distribution within polygons in gully distal hyporheic zones. Patterned ground morphological variation can serve as an indicator of fluvial modification, ranging from nearly unmodified composite-wedge polygons to polygons forming in association with gully channels. Thermal contraction crack polygons may also constrain the gully formation sequence, suggesting the continuous presence of permafrost beneath the Wright Valley gullies during the entire period of gully emplacement. This analysis provides a framework for understanding the relationships between polygons and gullies observed on Mars. If comparable stratigraphic relationships can be documented, the presence of an analogous impermeable ice-cemented layer beneath the gullies can be inferred, suggesting an atmospheric source for Martian gully-carving fluids.
Insects are by far the most diverse group of multicellular organisms on our planet. Of about 1,625,000 described species of prokaryotes, protoctists, fungi, plants and animals, more than 1 million is represented by arthropods, of which insects constitute the largest group with about 854,000 described species. The estimations of the number of still undescribed species, especially in the vanishing tropical rainforests, are ranging from 2 million to 80 million species! The most species-rich groups within insects are the holometabolous orders Coleoptera (beetles), Hymenoptera (ants, wasps and bees), Diptera (mosquitoes and flies) and Lepidoptera (moths and butterflies). Among the hemimetabolous orders, which lack a pupal stage in their ontogenetic development, the Hemiptera (aphids, scale insects, cicadas and bugs) are the largest group, while all other insect orders have much fewer species.
Even though relatively small animals, the extremely large number of individuals makes insects a very significant part of the total terrestrial biomass in many biotopes. For example, in tropical rainforests, the ants and termites have a higher total biomass than all the vertebrates combined.
Insects are not only diverse in terms of species number and number of individuals, but also in their astonishing anatomical and ecological variability. Insects populate nearly every available habitat on the planet, except for the open seas and the frozen polar regions.
Several debris-covered glaciers occupy tributaries of upper Beacon Valley, Antarctica. Understanding their flow dynamics and ice thickness is important for palaeoclimate studies and for understanding the origins of ancient ice elsewhere in the McMurdo Dry Valleys region. We present the results of several shallow seismic surveys in Mullins Valley, where the largest of these debris-covered glaciers is located. Our results suggest that beneath a thin sublimation till and near-surface horizon of dirty glacier ice, lies relatively pure glacier ice (P-wave velocity ~3700–3800 m s-1), with total thickness estimates of ~90–95 m towards the valley head, and ~40–65 m near the entrance to Beacon Valley, ~2.5 km downglacier. P-wave velocities decrease downvalley, suggesting that the material properties of the ice change with increasing distance from the ice-accumulation zone. These new data are used to calibrate an ice thickness profile for the active portion of the Mullins Valley debris-covered glacier (upper ~3.5 km) and to shed light on the origin and spatial distribution of enclosed debris.
The major dynamic forces shaping the surfaces, crusts, and lithospheres of planets are represented by geological processes (Figures 1.1–1.6) which are linked to interaction with the atmosphere (e.g., eolian, polar), with the hydrosphere (e.g., fluvial, lacustrine), with the cryosphere (e.g., glacial and periglacial), or with the crust, lithosphere, and interior (e.g., tectonism and volcanism). Interaction with the planetary external environment also occurs, as in the case of impact cratering processes. Geological processes vary in relative importance in space and time; for example, impact cratering was a key process in forming and shaping planetary crusts in the first one-quarter of Solar System history, but its global influence has waned considerably since that time. Volcanic activity is a reflection of the thermal evolution of the planet, and varies accordingly in abundance and style.
The stratigraphic record of a planet represents the products or deposits of these geological processes and how they are arranged relative to one another. The geological history of a planet can be reconstructed from an understanding of the details of this stratigraphic record. On Mars, the geological history has been reconstructed using the global Viking image data set to delineate geological units (e.g., Greeley and Guest, 1987; Tanaka and Scott, 1987; Tanaka et al., 1992), and superposition and cross-cutting relationships to establish their relative ages, with superposed impact crater abundance tied to an absolute chronology (e.g., Hartmann and Neukum, 2001).
We review new advances in volcano–ice interactions on Mars and focus additional attention on (1) recent analyses of the mechanisms of penetration of the cryosphere by dikes and sills; (2) documentation of the glacial origin of huge fan-shaped deposits on the northwest margins of the Tharis Montes and evidence for abundant volcano–ice interactions during the later Amazonian period of volcanic edifice construction and (3) the circumpolar Hesperian-aged Dorsa Argentea Formation, interpreted as an ice sheet and displaying marginal features (channels, lakes and eskers) indicative of significant melting and interior features interpreted to be due to volcano–ice interactions (e.g. subglacial volcanic edifices, pits, basins, channels and eskers). In this context, we describe and analyse several stages and types of volcano–ice interactions: (1) magmatic interactions with ice-rich parts of the cryosphere; (2) subglacial volcanism represented by intrusion under and into the ice and formation of dikes and moberg-like ridges, intrusion of sills at the glacier–volcano substrate interface and their evolution into subglacial lava flows, formation of subglacial edifices, marginal melting and channels; (3) synglacial (ice contact) volcanism represented by flows banking up against glacier margins, chilling and forming remnant ridges and (4) post-glacial volcanism and interactions with ice deposits.
We map polygonally patterned ground formed in sublimation tills that overlie debris-covered glaciers in Mullins Valley and central Beacon Valley, in southern Victoria Land, Antarctica, and distinguish five morphological zones. Where the Mullins Valley debris-covered glacier debouches into Beacon Valley, polygonal patterning transitions from radial (orthogonal) intersections to non-oriented (hexagonal) intersections, providing a time-series of polygon evolution within a single microclimate. We offer the following model for polygon formation and evolution in the Mullins Valley system. Near-vertical cracks that ultimately outline polygons are produced by thermal contraction in the glacier ice. Some of these cracks may initially be oriented radial to maximum surface velocities by pre-existing structural stresses and material weaknesses in the glacier ice. In areas of relatively rapid flow, polygons are oriented down-valley forming an overall fan pattern radial to maximum ice velocity. As glacier flow moves the cracks down-valley, minor variations in flow rate deform polygons, giving rise to deformed radial polygons. Non-oriented (largely hexagonal) polygons commonly form in regions of stagnant and/or near-stagnant ice. We propose that orientation and morphology of contraction-crack polygons in sublimation tills can thus be used as an indicator of rates of subsurface ice flow.
Field experiments were conducted at Ashland Bottoms in northeastern Kansas and at Hays in western Kansas in 2001, 2002, and 2003 to determine the response of soil microbial and nematode communities to different herbicides and tillage practices under a glyphosate-resistant cropping system. Conventional herbicide treatments were a tank mixture of cloransulam plus S-metolachlor plus sulfentrazone for soybean and a commercially available mixture of acetochlor and atrazine for corn. Glyphosate was applied at 1.12 kg ai ha−1 when weeds were 10 or 20 cm tall in both corn and soybean. Soil samples were collected monthly at Ashland Bottoms during the growing period for soil microbial biomass (SMB) carbon determination. In addition, substrate-induced respiration (SIR) and BIOLOG substrate utilization were determined at the end of the growing season each year at Ashland Bottoms, and nematode populations were determined at the beginning and the end of the growing season at both sites. Direct effects of glyphosate rates on soil microbial and nematode communities were also studied in a controlled environment. Values for SMB carbon, SIR, and BIOLOG substrate utilization were not altered by glyphosate. Nematode community response to the glyphosate treatment was similar under both conventional tillage and no-till environments. Total nematode densities were similar with the glyphosate and conventional herbicide treatments. SMB carbon and BIOLOG substrate utilization did not differ between tillage treatments. Nematode densities were greater under conventional tillage than in the no-till system. This study showed that soil health when glyphosate was applied in a glyphosate-resistant cropping system was similar to that of cropping systems that used conventional herbicides.