Leaky Moss in Montana\u27s Grasslands

Grasslands cover more than 40% of Montana[1] and while much is known about the vascular plant community, little attention is paid to the role mosses play. Could these bryophytes be a key part in maintaining proper nutrient cycling and recruiting new plants? In our preliminary study we found that plant biomass is increased in the presence of moss, one explanation involves moss physiology. Mosses are fascinating organisms able to withstand extreme dehydration and can rehydrate within minutes. This rapid rehydration results in nutrient loss through ruptured cell walls, which we hypothesize is then leached into the soil and made available to surrounding organisms. In our current project we are investigating the nature of moss ‘leachate’ and what effect it has on native plants and nonnative plants in competition. Moss has been shown to facilitate plant growth through altering physical structure or water availability; we are focused on how mosses alter the nutrient cycling. Our common garden experiment will treat established grassland plants (C. stoebe, and F. idahoensis) with moss leachate for 4 weeks and measure final biomass. Furthermore, via elemental analysis, we will investigate the nature of moss leachate, quantifying the total organic carbon and nitrogen. Mosses grow in almost every ecosystem on the planet, and linking moss leachate as a key part of the nutrient cycle could yield many management implications. 1. Montana’s Comprehensive Fish and Wildlife Conservation Strategy, Executive Summary, 2005. Montana Fish, Wildlife & Park

Performing heritage: the use of live 'actors' in heritage presentations

This paper investigates the phenomenon of 'living history' presentations of heritage, using live 'actors' to portray historical characters. Its aim is to discuss these presentations in the context of what may be understood as 'heritage', and of the nature of 'performance'. Four case studies of heritage sites, each important as a tourist attraction, have been selected for detailed study, together with a number of other examples of heritage performance. It is clear from the empirical work that different performance strategies are employed within the heritage industry and by individual 'actors'. Most of the performers take part as a leisure activity, and many do not consider themselves to be 'performing' at all. The greatest concern of participants lies in the degree of authenticity of the performance. Through 'living history', the 'actors' are drawn into an experience of heritage which has real meaning for them, and which may contribute both to a sense of identity and to an enhanced understanding of society, past and present. The popularity of such presentations with visitors also indicates that similar benefits are perceived by the 'audience'

Integrating modes of policy analysis and strategic management practice : requisite elements and dilemmas

There is a need to bring methods to bear on public problems that are inclusive, analytic, and quick. This paper describes the efforts of three pairs of academics working from three different though complementary theoretical foundations and intervention backgrounds (i.e., ways of working) who set out together to meet this challenge. Each of the three pairs had conducted dozens of interventions that had been regarded as successful or very successful by the client groups in dealing with complex policy and strategic problems. One approach focused on leadership issues and stakeholders, another on negotiating competitive strategic intent with attention to stakeholder responses, and the third on analysis of feedback ramifications in developing policies. This paper describes the 10 year longitudinal research project designed to address the above challenge. The important outcomes are reported: the requisite elements of a general integrated approach and the enduring puzzles and tensions that arose from seeking to design a wide-ranging multi-method approach

Depletion forces near curved surfaces

Based on density functional theory the influence of curvature on the depletion potential of a single big hard sphere immersed in a fluid of small hard spheres with packing fraction \eta_s either inside or outside of a hard spherical cavity of radius R_c is calculated. The relevant features of this potential are analyzed as function of \eta_s and R_c. There is a very slow convergence towards the flat wall limit R_c \to \infty. Our results allow us to discuss the strength of depletion forces acting near membranes both in normal and lateral directions and to make contact with recent experimental results

Effect of EMIC waves on relativistic and ultrarelativistic electron populations: Ground-based and Van Allen Probes observations

Abstract We study the effect of electromagnetic ion cyclotron (EMIC) waves on the loss and pitch angle scattering of relativistic and ultrarelativistic electrons during the recovery phase of a moderate geomagnetic storm on 11 October 2012. The EMIC wave activity was observed in situ on the Van Allen Probes and conjugately on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity throughout an extended 18 h interval. However, neither enhanced precipitation of \u3e0.7 MeV electrons nor reductions in Van Allen Probe 90° pitch angle ultrarelativistic electron flux were observed. Computed radiation belt electron pitch angle diffusion rates demonstrate that rapid pitch angle diffusion is confined to low pitch angles and cannot reach 90°. For the first time, from both observational and modeling perspectives, we show evidence of EMIC waves triggering ultrarelativistic (~2-8 MeV) electron loss but which is confined to pitch angles below around 45° and not affecting the core distribution. Key Points EMIC wave activity is not associated with precipitation of MeV electrons EMIC waves do not deplete the ultra-relativistic belt down to 90° EMIC waves cause loss of low pitch angle electrons with energies ~2-8 MeV

Hard Spheres in Vesicles: Curvature-Induced Forces and Particle-Induced Curvature

We explore the interplay of membrane curvature and nonspecific binding due to excluded-volume effects among colloidal particles inside lipid bilayer vesicles. We trapped submicron spheres of two different sizes inside a pear-shaped, multilamellar vesicle and found the larger spheres to be pinned to the vesicle's surface and pushed in the direction of increasing curvature. A simple model predicts that hard spheres can induce shape changes in flexible vesicles. The results demonstrate an important relationship between the shape of a vesicle or pore and the arrangement of particles within it.Comment: LaTeX with epsfig; ps available at http://dept.physics.upenn.edu/~nelson/index.shtml Phys Rev Lett in press (1997

Primary mediastinal large B-cell lymphoma in HIV: report of two cases

Primary mediastinal large B cell lymphoma (PMLBCL) is a subtype of diffuse large B cell lymphoma arising in the mediastinum with distinctive clinical and morphological features. Though diffuse large B cell lymphoma is one of the most common non-Hodgkin lymphoma associated with AIDS, there are no data available regarding the association of HIV and PMLBCL. We report here two cases of PMLBCL arising in AIDS patients. In both cases, PMLBCL presented in a setting of low CD4 T-cell count as rapidly enlarging mediastinal mass. The morphologic and immunophenotypic findings are characteristic of PMLBCL. One of the two patients, a 25-year-old woman who had localized disease and evidence of Epstein–Barr virus in lymphoma cells, did not respond to chemotherapy and died of disease progression 5 months after diagnosis. The second patient, a 38-year-old male with disseminated disease, responded to therapy and is disease-free after 9 months of follow-up

Depletion potential in hard-sphere mixtures: theory and applications

We present a versatile density functional approach (DFT) for calculating the depletion potential in general fluid mixtures. In contrast to brute force DFT, our approach requires only the equilibrium density profile of the small particles {\em before} the big (test) particle is inserted. For a big particle near a planar wall or a cylinder or another fixed big particle the relevant density profiles are functions of a single variable, which avoids the numerical complications inherent in brute force DFT. We implement our approach for additive hard-sphere mixtures. By investigating the depletion potential for high size asymmetries we assess the regime of validity of the well-known Derjaguin approximation for hard-sphere mixtures and argue that this fails. We provide an accurate parametrization of the depletion potential in hard-sphere fluids which should be useful for effective Hamiltonian studies of phase behavior and colloid structure