Dust Devil Tracks

Dust devils that leave dark- or light-toned tracks are common on Mars and they can also be found on the Earth’s surface. Dust devil tracks (hereinafter DDTs) are ephemeral surface features with mostly sub-annual lifetimes. Regarding their size, DDT widths can range between ∼1 m and ∼1 km, depending on the diameter of dust devil that created the track, and DDT lengths range from a few tens of meters to several kilometers, limited by the duration and horizontal ground speed of dust devils. DDTs can be classified into three main types based on their morphology and albedo in contrast to their surroundings; all are found on both planets: (a) dark continuous DDTs, (b) dark cycloidal DDTs, and (c) bright DDTs. Dark continuous DDTs are the most common type on Mars. They are characterized by their relatively homogenous and continuous low albedo surface tracks. Based on terrestrial and martian in situ studies, these DDTs most likely form when surficial dust layers are removed to expose larger-grained substrate material (coarse sands of ≥500 μm in diameter). The exposure of larger-grained materials changes the photometric properties of the surface; hence leading to lower albedo tracks because grain size is photometrically inversely proportional to the surface reflectance. However, although not observed so far, compositional differences (i.e., color differences) might also lead to albedo contrasts when dust is removed to expose substrate materials with mineralogical differences. For dark continuous DDTs, albedo drop measurements are around 2.5 % in the wavelength range of 550–850 nm on Mars and around 0.5 % in the wavelength range from 300–1100 nm on Earth. The removal of an equivalent layer thickness around 1 μm is sufficient for the formation of visible dark continuous DDTs on Mars and Earth. The next type of DDTs, dark cycloidal DDTs, are characterized by their low albedo pattern of overlapping scallops. Terrestrial in situ studies imply that they are formed when sand-sized material that is eroded from the outer vortex area of a dust devil is redeposited in annular patterns in the central vortex region. This type of DDT can also be found in on Mars in orbital image data, and although in situ studies are lacking, terrestrial analog studies, laboratory work, and numerical modeling suggest they have the same formation mechanism as those on Earth. Finally, bright DDTs are characterized by their continuous track pattern and high albedo compared to their undisturbed surroundings. They are found on both planets, but to date they have only been analyzed in situ on Earth. Here, the destruction of aggregates of dust, silt and sand by dust devils leads to smooth surfaces in contrast to the undisturbed rough surfaces surrounding the track. The resulting change in photometric properties occurs because the smoother surfaces have a higher reflectance compared to the surrounding rough surface, leading to bright DDTs. On Mars, the destruction of surficial dust-aggregates may also lead to bright DDTs. However, higher reflective surfaces may be produced by other formation mechanisms, such as dust compaction by passing dust devils, as this may also cause changes in photometric properties. On Mars, DDTs in general are found at all elevations and on a global scale, except on the permanent polar caps. DDT maximum areal densities occur during spring and summer in both hemispheres produced by an increase in dust devil activity caused by maximum insolation. Regionally, dust devil densities vary spatially likely controlled by changes in dust cover thicknesses and substrate materials. This variability makes it difficult to infer dust devil activity from DDT frequencies. Furthermore, only a fraction of dust devils leave tracks. However, DDTs can be used as proxies for dust devil lifetimes and wind directions and speeds, and they can also be used to predict lander or rover solar panel clearing events. Overall, the high DDT frequency in many areas on Mars leads to drastic albedo changes that affect large-scale weather patterns

The role of marketing in matching industry needs with technologies developed at Oak Ridge National Laboratory

National laboratories have limited resources to devote to the transfer of government-funded technologies to the commercial sector. Companies, too, face resource constraints in their attempt to identify and assimilate innovations which fit with their strategic objectives. For these reasons, persons engaged in technology transfer should attempt to identify laboratory developments which represent the best possible match with industry needs and focus their attention on those technologies which are most likely to make and impact in the marketplace. In a structured approach designed to meet this objective, Martin Marietta Energy Systems, which operates Oak Ridge National Laboratory for the Department of Energy, has established formal ties with the University of Tennessee Business School, to enhance the role of marketing for technology transfer. The school's MBA students continue to play a key role in the formulation and execution of plans designed to transform Oak Ridge technologies into new products, new jobs, and economic prosperity for US companies

Analysis of ß-subgroup proteobacterial ammonia oxidizer populations in soil by denaturing gradient gel electrophoresis analysis and hierarchical phylogenetic probing

A combination of denaturing gradient gel electrophoresis (DGGE) and oligonucleotide probing was used to investigate the influence of soil pH on the compositions of natural populations of autotrophic beta-subgromp proteobacterial ammonia oxidizers. PCR primers specific to this group were used to amplify 16S ribosomal DIVA (rDNA) from soils maintained for 36 years at a range of pH values, and PCR products were analyzed by DGGE, Genus- and cluster-specific probes were designed to bind to sequences within the region amplified by these primers, A sequence specific to all beta-subgroup ammonia oxidizers could not be identified, but probes specific for Nitrosospira clusters 1 to 4 and Nitrosomonas clusters 6 and 7 (J. R. Stephen, A. E. McCaig, Z. Smith, J. I. Presser, and T. M. Embley, Appl. Environ. Microbiol. 62:4147-4154, 1996) were designed. Elution profiles of probes against target sequences and closely related nontarget sequences indicated a requirement for high-stringency hybridization conditions to distinguish between different clusters, DGGE banding patterns suggested the presence of Nitrosomonas cluster 6a and Nitrosospira clusters 2, 3, and 4 in all soil plots, but results mere ambiguous because of overlapping banding patterns, Unambiguous hand identification of the same clusters was achieved by combined DGGE and probing of blots with the cluster-specific radiolabelled probes, The relative intensities of hybridization signals provided information on the apparent selection of different Nitrosospira genotypes in samples of soil of different pHs. The signal from the Nitrosospira cluster 3 probe decreased significantly, relative to an internal control probe, with decreasing soil pH in the range of 6.6 to 3.9, while Nitrosospira cluster 2 hybridization signals increased with increasing soil acidity. Signals from Nitrosospira cluster 4 were greatest at pH 5.5, decreasing at lower and higher values, while Nitrosomonas cluster 6a signals did not vary significantly with pH. These findings are in agreement with a previous molecular study (J, R Stephen, A. E. McCaig, Z. Smith, J. I, Presser, and T, M. Embley, Appl, Environ. Microbiol 62:4147-4154, 1996) of the same sites, which demonstrated the presence of the same four clusters of ammonia oxidizers and indicated that selection might be occurring for clusters 2 and 3 at acid and neutral pHs, respectively. The two studies used different sets of PCR primers for amplification of 16S rDNA sequences from soil, and the similar findings suggest that PCR bias was unlikely to be a significant factor, The present study demonstrates the value of DGGE and probing for rapid analysis of natural soil communities of beta-subgroup proteobacterial ammonia oxidizers, indicates significant pH-associated differences in Nitrosospira populations, and suggests that Nitrosospira cluster 2 may be of significance for ammonia- oxidizing activity in acid soils. [KEYWORDS: 16s ribosomal-rna; nitrifying bacteria; gene-sequences; low ph; autotrophic nitrification; purple bacteria; diversity; organization; subdivision; oxidation]

Alpine compressional tectonics in the Southern Alps. Relationships with the N-Apennines

The southern Alps orogenic development has been produced by non-cylindrical accretion of arcuated thrust belts. The western-northern sector of the chain is occupied by the Orobic Arc, an Eoalpine to Mesoalpine structural system including the Grigna and Presolana overthrusts. The radiometric age of the dykes cutting the overthrusting contacts suggests Late Cretaceous as the age of the principal tectonic emplacement. Apart from the Dinaridic influence in the eastern sector, the remaining parts of the Southern Alps were deformed mainly by the Oligo-Miocene, Miocene and Pio-Pleistocene events. The Chattian to Burdigalian tectonic phase (mainly Aquitanian in age) produced the backthrust system during the Gonfolite l.s. sedimentation. This WNW-trending compressions] belt predominates in the Po Plain subsurface between the Piedmont and Lombardy regions. Prominent tectonic structures belonging to this system also outcrop in eastern Lombardy. The structures of \uabDinaric phase\ubb in the Dolomites may be referred mainly to this event; in this picture the Mt. Parei conglomerates could be an equivalent of the Lombardian Gonfolite. The Middle-Late Miocene compressional events produced widespread deformation in the central and eastern regions of the Southern Alps with ENE-trending prevailing structures, including the NNE trending thrusts of the Giudicarie region. The Messinian to Plo-Pleistocene compressional structures mainly affected the eastern regions of the Southern Alps along the southernmost border in the Friuli external arc. This last belt is probably kinematically linked to the buried frontal Apennine chain. A comparison between the neoalpine tectonic accretion of the Southern Alps and the Northern Apennines is attempted in the frame of the geodynamic evolution of the Western Mediterranean domains

Structural and kinematic analysis of the Giudicarie deformation belt. Implication for compressional tectonics of Southern Alps

This paper reports the results of a structural study of the deformational belt developing around the Giudicarie tectonic lineament in the central Southern Alps of Italy. Three different, non-coaxial systems of deformation has been recognized from the analysis of the mesoscopic structures such as systems of veins and pressure-solution clevages, fold system and fold superposition, and the stress inversion from fault populations. The structural setting of the Giudicarie belt results from the superposition in time of these deformational systems, which correspond to diverse tectonic stages of the neoalpine tectonics