Dynamical hierarchy in transition states: Why and how does a system climb over the mountain?

How a reacting system climbs through a transition state during the course of a reaction has been an intriguing subject for decades. Here we present and quantify a technique to identify and characterize local invariances about the transition state of an N-particle Hamiltonian system, using Lie canonical perturbation theory combined with microcanonical molecular dynamics simulation. We show that at least three distinct energy regimes of dynamical behavior occur in the region of the transition state, distinguished by the extent of their local dynamical invariance and regularity. Isomerization of a six-atom Lennard–Jones cluster illustrates this: up to energies high enough to make the system manifestly chaotic, approximate invariants of motion associated with a reaction coordinate in phase space imply a many-body dividing hypersurface in phase space that is free of recrossings even in a sea of chaos. The method makes it possible to visualize the stable and unstable invariant manifolds leading to and from the transition state, i.e., the reaction path in phase space, and how this regularity turns to chaos with increasing total energy of the system. This, in turn, illuminates a new type of phase space bottleneck in the region of a transition state that emerges as the total energy and mode coupling increase, which keeps a reacting system increasingly trapped in that region.

Locust adipokinetic hormones: carrier-independent transport and differential inactivation at physiological concentrations during rest and flight.

Since concomitant release of structurally related peptide hormones with apparently similar functions seems to be a general concept in endocrinology, we have studied the dynamics of the lifetime of the three known adipokinetic hormones (AKHs) of the migratory locust, which control flight-directed mobilization of carbohydrate and lipid from fat body stores. Although the structure of the first member of the AKHs has been known for 20 years, until now, reliable data on their inactivation and removal from the hemolymph are lacking, because measurement requires AKHs with high specific radioactivity. Employing tritiated AKHs with high specific radioactivity, obtained by catalytic reduction with tritium gas of the dehydroLeu2 analogues of the AKHs synthesized by the solid-phase procedure, studies with physiological doses of as low as 1.0 pmol per locust could be conducted. The AKHs appear to be transported in the hemolymph in their free forms and not associated with a carrier protein, despite their strong hydrophobicity. Application of AKHs in their free form in in vivo and in vitro studies therefore now has been justified. We have studied the degradation of the three AKHs during rest and flight. The first cleavage step by an endopeptidase is crucial, since the resulting degradation products lack any adipokinetic activity. Half-lives for AKH-I, -II and -III were 51, 40, and 5 min, respectively, for rest conditions and 35, 37, and 3 min, respectively, during flight. The rapid and differential degradation of structurally related hormones leads to changes in the ratio in which they are released and therefore will have important consequences for concerted hormone action at the level of the target organ or organs, suggesting that each of the known AKHs may play its own biological role in the overall syndrome of insect flight.

Developing an Interdependent Relationship between Preservation and Recreation: Managing Mountain Bicycling in National Parks

Increasing demand from mountain bikers for greater access to riding in National Park Service (NPS) units is driving the need for park managers to seriously look at the impacts from and feasibility of permitting this recreational use. Currently, NPS units that permit mountain bicycling do not have formal mountain bicycling management plans. An analysis of recreational policies and existing research was conducted to identify criteria for effective mountain bicycling management strategies. Criteria were developed for trail selection, establishment, use, closures and rehabilitation. Criteria were also developed for user education, participatory planning and monitoring. This study shows that the NPS needs formal mountain bicycling management plans that focus on the preservation of natural and cultural resources and consider the appropriateness of proposed recreational uses.

Renewable Energy Generation at Copper Mountain Resort

Copper Mountain, a Colorado ski area, evaluated onsite renewable energy generation to save on energy costs and reduce carbon emissions. Multiple resort locations were analyzed to determine suitable sites for implementation of solar electricity generation, wind electricity generation and biomass heat production. Potential project sites were assessed based on four criteria: costs and financial returns, environmental impacts, implementation and maintenance, and public relations/marketing opportunities. Solar projects had the lowest capital cost of the three types of renewable energy, and wind projects had high capital costs and low financial returns. Biomass projects had high capital costs, solid financial projections and good marketing value compared to wind and solar technologies. Project implementation recommendations were given based upon the evaluation.

Improving Colorado Mountain Highway Culvert Stream Crossings for Trout Passage

Highways can be effective barriers to animal migration. Where highways cross over streams, a passageway, typically a culvert, not designed for fish access can cut off an organism from miles of habitat. Traditional methods of culvert design, to convey floodwaters, reduced access to aquatic and riparian range. The Colorado Department of Transportation likely has numerous culverts that restrict aquatic passage. This paper provides guidance to CDOT for assessment of stream geomorphic conditions affecting culvert performance for fish passage, understanding aquatic organism habitat requirements, and incorporating ecological parameters into culvert designs that benefit fish and other organisms. A case study illustrates culvert problems in a difficult geomorphic setting including a fish passage assessment to evaluate stream stability for long-term culvert reliability.

A Physical and Social Study of Mountain Bike Use on Five Segments of the Continental Divide National Scenic Trail in Colorado

This capstone reviews uses of the Continental Divide National Scenic Trail. Policies governing use of the trail appear to be ambiguous, especially regarding mountain bicycles. Mountain biking has grown since the trail was created, but is not fully addressed in existing or proposed policy. 382 people on five segments of the trail in Colorado were interviewed for this capstone. Mountain bikes, hiking, and motorized recreation were observed uses. User conflict, overcrowding, degraded recreation experiences, or user displacement was not reported. User satisfaction was high and most would return. Interviewees requested increased public involvement and recognition of user needs in setting policy. Trail degradation occurs, but is unassociated with any particular use. Recommendations for trail improvement and maintenance are presented.

Factors Affecting Women Leaders in the Denver Group of the Colorado Mountain Club

A study of women leaders in the Colorado Mountain Club (CMC) demonstrated that this group perceived pace as an impediment to leadership growth. This study is an exploratory-quantitative inquiry that assessed the views of 20 of the active women hike leaders in the Denver group. The author designed a survey of factors women hike leaders would rate according to their CMC experiences. Although there are more women members of the Denver group, women leaders comprise only 30% of the leadership group The results from this first ever survey of CMC's women leaders provides a knowledge base for CMC and other interested parties. This study clearly demonstrated the need for more research into its topic of women in leadership positions.

Successional stage after land abandonment modulates fire severity and post-fire recovery in a Mediterranean mountain landscape

This study analyses the effect of successional stage after farmland terrace abandonment on post-fire plant recovery in a Mediterranean landscape. Specific objectives of the study were to (1) compare fuel characteristics and fire severity in three successional stages after farmland abandonment – dry grassland, dense shrubland and pine stands; (2) analyse the effect of pre-fire successional stage and fire severity on vegetation recovery and (3) analyse the relative vulnerability (i.e. potential for ecosystem shift and soil degradation) to wildfires of the successional stages. We assessed 30 abandoned terraces (15 unburned and 15 burned), with diverse successional stages, on the Xortà Range (south-east Spain). Post-fire recovery was measured 1, 4 and 7 years after fire. The successional stages varied in aboveground biomass, litter amount, vertical structure and continuity of plant cover, and flammability. Dry grassland showed the lowest fire severity, whereas no differences in severity were found between shrubland and pine stands. One year after fire, plant cover was inversely related to fire severity; this relationship attenuated with time after fire. Post-fire recovery of pine stands and shrubland led in both cases to shrublands, contributing to landscape homogenisation. The pine stands showed the largest changes in composition due to fire and the lowest post-fire plant recovery – a sign of high vulnerability to fire.