Michigan Technological University

About: Michigan Technological University is a education organization based out in Houghton, Michigan, United States. It is known for research contribution in the topics: Population & Volcano. The organization has 8023 authors who have published 17422 publications receiving 481780 citations. The organization is also known as: MTU & Michigan Tech.

Dispersal of ash in the great Toba eruption, 75 ka

Abstract: One of Earth9s largest known eruptions, the Toba eruption of 75 ka, erupted a minimum of 2800 km 3 of magma, of which at least 800 km 3 was deposited as ash fall. This ash may be entirely of coignimbrite origin and dispersed widely because of high drag coefficients on the predominantly bubble-wall shards. Shards of this shape are broken from the walls of spherical vesicles, which formed in high abundance in isotropic strain shadows near phenocrysts in this crystal-rich magma.

A gradient flow theory of plasticity for granular materials

Abstract: A flow theory of plasticity for pressure-sensitive, dilatant materials incorporating second order gradients into the flow-rule and yield condition is suggested. The appropriate extra boundary conditions are obtained with the aid of the principle of virtual work. The implications of the theory into shear-band analysis are examined. The determination of the shear-band thickness and the persistence of ellipticity in the governing equations are discussed.

CO2 Electroreduction to Hydrocarbons on Carbon-Supported Cu Nanoparticles

Abstract: Activities of Cu nanoparticles supported on carbon black (VC), single-wall carbon nanotubes (SWNTs), and Ketjen Black (KB) toward CO2 electroreduction to hydrocarbons (CH4, C2H2, C2H4, and C2H6) are evaluated using a sealed rotating disk electrode (RDE) setup coupled to a gas chromatograph (GC). Thin films of supported Cu catalysts are deposited on RDE tips following a procedure well-established in the fuel cell community. Lead (Pb) underpotential deposition (UPD) is used to determine the electrochemical surface area (ECSA) of thin films of 40 wt % Cu/VC, 20 wt % Cu/SWNT, 50 wt % Cu/KB, and commercial 20 wt % Cu/VC catalysts on glassy carbon electrodes. Faradaic efficiencies of four carbon-supported Cu catalysts toward CO2 electroreduction to hydrocarbons are compared to that of electrodeposited smooth Cu films. For all the catalysts studied, the only hydrocarbons detected by GC are CH4 and C2H4. The Cu nanoparticles are found to be more active toward C2H4 generation versus electrodeposited smooth copper ...

Preparing for climate change: Forestry and assisted migration

Abstract: Although plants have moved across the landscape in response to changing climate for millennia, projections of contemporary climate change suggest that forest tree species and populations will need to migrate faster than their natural ability. Therefore, climate change adaptation strategies, such as assisted migration, have gained attention since 2007. Effective implementation of assisted migration can only occur if target transfer guidelines are developed because our current seed transfer guidelines, established to guide the movement of plant materials, lack inherent spatial and temporal dynamics associated with climate change. This limitation restrains reforestation practitioners from making decisions about assisted migration. Lack of operating procedures, uncertainties about future climate conditions, risks associated with moving plants outside their current ranges, and existing policies have hampered formal actions in forest management and conservation. We review the current thinking on assisted migration of forest tree species and provide information that could facilitate implementation.

Effects of Forest Roads on Understory Plants in a Managed Hardwood Landscape

Abstract: The effect of forest roads on species distribution and dispersal is an important conservation and management issue. We examined distributions of understory plants and their relationships to unpaved forest roads in a northern hardwood landscape in the Chequamegon National Forest, Wisconsin (U.S.A.). At six dif- ferent sites, we recorded species cover, canopy cover, litter depth and cover, and bare ground at 11 distances (0, 5, 10, 15, 20, 30, 45, 60, 90, 120, and 150 m) from the road edge. At each of the 11 distances, we estab- lished a 60-m transect parallel to the road edge, within which we sampled 10 randomly placed 1 � 1 m plots (660 plots). We examined changes in species abundance (percent species cover per plot), richness, and Shan- non-Wiener diversity ( H � ) with distance from the roads in an effort to determine the degree and magnitude of road effects on plant distribution. The species richness and Hof native plants and the abundance of exotic species were clearly related to distance from the roads. Exotic species were most prevalent within 15 m of roads, occurring infrequently in the interior forest. The richness and Hof native species were lower on the roadsides but reached interior-forest levels within a short distance (5 m) from the roads. The roads appeared to be associated with a disturbance corridor that affected site variables up to 15 m into the hardwood stands. At our six sites we detected 117 species, 25% of which occurred more frequently near the road, with only 12% having a 90% or greater preference for the forest interior. Our results suggest that roads have associated ef- fects that alter interior-forest conditions and thus plant species composition and abundance; however, these effects are limited in depth of penetration into managed forests.