Kolmogorov-Burgers Model for Star Forming Turbulence

The process of star formation in interstellar molecular clouds is believed to be controlled by driven supersonic magnetohydrodynamic turbulence. We suggest that in the inertial range such turbulence obeys the Kolmogorov law, while in the dissipative range it behaves as Burgers turbulence developing shock singularities. On the base of the She-Leveque analytical model we then predict the velocity power spectrum in the inertial range to be E_k ~ k^{-1.74}. This result reproduces the observational Larson law, ~ l^{0.74...0.76}, [Larson, MNRAS 194 (1981) 809] and agrees well with recent numerical findings by Padoan and Nordlund [astro-ph/0011465]. The application of the model to more general dissipative structures, with higher fractal dimensionality, leads to better agreement with recent observational results.Comment: revised, new material added, 8 page

AGRICULTURAL ADAPTATION TO URBANIZATION IN SOUTHEASTERN PENNSYLVANIA

Most agricultural output in the northeastern United States comes from counties that have experienced significant development. A mail survey, with 300 responses, was conducted in southeastern Pennsylvania to determine farmer adaptation to urbanization in this region. Despite development, traditional agriculture still predominates. Changes in land use were examined using multinomial logit models. Results show that change in population density and farm preservation policies have an influence, as increased population density reduced total land operated and having land in an agricultural security area increased it. Both differential assessment and agricultural security areas increased the cultivation of traditional, land extensive crops.Agricultural and Food Policy, Community/Rural/Urban Development,

LOCATIONAL EFFECTS OF URBANIZATION ON AGRICULTURE IN SOUTHEASTERN PENNSYLVANIA

Most agricultural output in the northeastern United States comes from counties that have experienced significant development. A mail survey, with 300 responses, was conducted in southeastern Pennsylvania to determine farmer adaptation to urbanization in this region. Despite development, traditional agriculture still predominates. Changes in land use were examined using multinomial logit models. Results show that changes in population density and farm preservation policies have an influence, as increased population density reduced total land operated and having land in an agricultural security area increased it. Other measures of urbanization, such as proximity to a city or inter-state highway had no statistically significant effect on farm practices. Keywords: Agricultural adaptation, rural development, off-farm income, urbanization, land useAgricultural adaptation, rural development, off-farm income, urbanization, land use, Land Economics/Use,

Constraints on Stirring and Dissipation of MHD Turbulence in Molecular Clouds

We discuss constraints on the rates of stirring and dissipation of MHD turbulence in molecular clouds. Recent MHD simulations suggest that turbulence in clouds decays rapidly, thus providing a significant source of energy input, particularly if driven at small scales by, for example, bipolar outflows. We quantify the heating rates by combining the linewidth-size relations, which describe global cloud properties, with numerically determined dissipation rates. We argue that, if cloud turbulence is driven on small internal scales, the $^{12}$CO flux (enhanced by emission from weakly supersonic shocks) will be much larger than observed; this, in turn, would imply excitation temperatures significantly above observed values. We reach two conclusions: (1) small-scale driving by bipolar outflows cannot possibly account for cloud support and yield long-lived clouds, unless the published MHD dissipation rates are seriously overestimated; (2) driving on large scales (comparable to the cloud size) is much more viable from an energetic standpoint, and if the actual net dissipation rate is only slightly lower than what current MHD simulations estimate, then the observationally inferred lifetimes and apparent virial equilibrium of molecular clouds can be explained.Comment: 5 pages, 1 figure. To appear in ApJ (2001 April 10

LAND TITLING IN PERU: IS IT FULFILLING ITS PROMISE?

The objective of this paper is to determine the impact of land titling in coastal Peru on the beneficiaries of this program. The paper examines the effects of land titling on access to credit, on-farm investment, the use of conservation techniques and the functioning of land markets.Land Economics/Use,

Analysis Concerning the Disaster of the Forest: A Theoretical and Practical Approach: Working Paper Series--04-09

The explosion of serious forest fires in the Rocky Mountain West in recent years has opened the public eye to the unhealthy condition of forests. The extended drought has combined with dense forest conditions to make many residents of rural Arizona quite fearful of the possibility of additional fires. The public interest has even resulted in federal policy changes known as the Healthy Forests Initiative, which has, of course, stimulated increased public discussion. In order to find solutions to the problem, as based on Norgaard, Smith and Jacobs, society must create new ways of organizing and doing. This article explores possible market-based solutions as the one of the available practical remediation processes. Utilizing the forest restoration and engineering literature, we believe that a new forest-based industry founded on the concepts of science-based forest management and ecological sustainability is the logical solution in a market-based economy

Predicting Black Bear Activity at Backcountry Campsites in Bryce Canyon National Park, Utah

Developing the capacity to predict black bear (Ursus americanus; bear) activity in a diversity of habitats will help conserve bear populations and their habitats and minimize human–bear conflicts. This capacity will be particularly important in areas that provide bear habitat and offer backcountry hiking and camping experiences. Bryce Canyon National Park (BRCA), located on the edge of the Paunsaugunt Plateau in southern Utah, USA, provides important bear habitat and offers visitors 12 backcountry campsites. To effectively manage these areas to minimize human–bear conflicts, park managers will need better information about black bear use of these campsites and other anthropogenic features in the BRCA. From 2014–2016, we studied the nature and frequency of bear activity within BRCA, with an emphasis on bear–campsite relationships, by analyzing bear activity data using radio-collared bears, remote camera monitoring of areas containing features of interest, campsite assessments, and analysis of human–bear interaction reports. We further assessed and ranked each backcountry campsite regarding its bear habitat quality, bear displacement potential, and human–bear conflict potential. Model selection showed bear preference for campsites and springs and avoidance of trails and roads. During site assessments, we identified a number of modifications to existing campsites that may help minimize human– bear interactions. Foremost among these changes is the relocation of campsites farther off-trail to avoid bears using trails. Specifically, we recommend that campsites be no closer than 200 m to permanent water sources. Finally, while the park requires the use of bear-resistant food containers, we recommend backcountry visitors also be encouraged to carry bear spray

Feasibility analysis of reciprocating magnetic heat pumps

The conceptual design selected for detailed system analysis and optimization is the reciprocating gadolinium core in a regenerative fluid column within the bore of a superconducting magnet. The thermodynamic properties of gadolinium are given. A computerized literature search for relevant papers was conducted and is being analyzed. Contact was made with suppliers of superconducting magnets and accessories, magnetic materials, and various types of hardware. A description of the model for the thermal analysis of the core and regenerator fluids is included

NEW AND UPDATED RECORDS FOR AMPHIBIANS AND REPTILES IN MINNESOTA, USA

Following the publication of the revised edition of “Amphibians and Reptiles in Minnesota” by Moriarty and Hall (2014), we accessioned several new or updated records at the Bell Museum of Natural History (JFBM). Records include digital photographs (accession number preceded by “P”) and audio recordings (accession number preceded by “AUD”). In addition, a subset of these observations were accessioned in www.HerpMapper.org. HerpMapper accession numbers are preceded by “HM” and can be viewed online. Benjamin Lowe verified species determinations. Latitude and longitude coordinates are based on datum WGS 84

Low-Metallicity Star Formation : Prestellar Collapse and Protostellar Accretion in the Spherical Symmetry

The collapse of dense cores with different metallicities is studied by hydrodynamical calculations coupled with detailed chemical and radiative processes. For this purpose, we construct a simple chemical network with non-equilibrium reactions among 15 chemical species, which reproduces the abundance of important molecular coolants by more detailed network very well. The evolution is followed until the formation of a hydrostatic protostar at the center. In a lower-metallicity gas cloud, the temperature during the collapse remains high owing to less efficient cooling. Using the temperature evolution at the center as a function the density, we discuss the possibility of fragmentation during the dust-cooling phase. The critical metallicity for the fragmentation is 10^{-5}Z_sun assuming moderate elongation of the cloud cores at the onset of this phase. From the density and velocity distributions at the time of protostar formation, we evaluate the mass accretion rate in the subsequent accretion phase. Using these accretion rates, we also calculate the evolution of the protostars under the assumption of stationary accretion flow. Finally, we discuss possible suppression of fragmentation by heating of the ambient gas by protostellar radiation, which is considered important in the contemporary star formation. We argue that it is negligible for <10^{-2}Zsun.Comment: ApJ in pres