915 research outputs found
An Ecological Basis for Ecosystem Management
This report was prepared by the Southwestern Regional Ecosystem Management Study Team composed of management and research biologists. The USDA Forest Service Southwestern Regions Regional Forester, Larry Henson, and the Rocky Mountain Forest and Range Experiment Station Director, Denver Burns, chartered this team to recommend an ecological basis for ecosystem management. This report is not intended to provide details on all aspects of ecosystem management; it simply provides information and makes recommendations for an ecological basis for ecosystem management. The report is not a decision document. It does not allocate resources on public lands nor does it make recommendations to that effect. The report of this Study Team may be relied upon as input in processes initiated under the National Environmental Policy Act (NEPA), National Forest Management Act (NFMA), Endangered Species Act (ESA), Administrative Procedures Act (APA), and other applicable laws. The information contained in this report is general in nature, rather than site specific. Implementation of ecosystem management and allocation of resources on Forest Service administered lands is the responsibility of the National Forest System in partnership with Forest Service Research and State and Private Forestry. Implementation is done through Forest and project plans that are subject to the NEPA process of disclosing the effects of proposed actions and affording the opportunity for public comment. The Southwestern Region follows a planning process for projects called Integrated Resource Management (IRM). The opinions expressed by the authors do not necessarily represent the policy or position of the U.S. Department of Agriculture, the Forest Service, The Nature Conservancy, or the Arizona Game and Fish Department. The Study Team acknowledges the valuable input of more than 50 individuals from various agencies, universities, professional organizations, and other groups who provided thoughtful comments of an earlier draft of this document. Some of their comments are included in Appendix 3
Thinking about growth : a cognitive mapping approach to understanding small business development
School of Managemen
Effect of tensor couplings in a relativistic Hartree approach for finite nuclei
The relativistic Hartree approach describing the bound states of both
nucleons and anti-nucleons in finite nuclei has been extended to include tensor
couplings for the - and -meson. After readjusting the parameters
of the model to the properties of spherical nuclei, the effect of
tensor-coupling terms rises the spin-orbit force by a factor of 2, while a
large effective nucleon mass sustains. The overall
nucleon spectra of shell-model states are improved evidently. The predicted
anti-nucleon spectra in the vacuum are deepened about 20 -- 30 MeV.Comment: 31 pages, 4 postscript figures include
Inducible neuronal PrP knockout mice reveal potential therapeutic window for TSE intervention
Two-dimensional Quantum-Corrected Eternal Black Hole
The one-loop quantum corrections to geometry and thermodynamics of black hole
are studied for the two-dimensional RST model. We chose boundary conditions
corresponding to the eternal black hole being in the thermal equilibrium with
the Hawking radiation. The equations of motion are exactly integrated. The one
of the solutions obtained is the constant curvature space-time with dilaton
being a constant function. Such a solution is absent in the classical theory.
On the other hand, we derive the quantum-corrected metric (\ref{solution})
written in the Schwarzschild like form which is a deformation of the classical
black hole solution \cite{5d}. The space-time singularity occurs to be milder
than in classics and the solution admits two asymptotically flat black hole
space-times lying at "different sides" of the singularity. The thermodynamics
of the classical black hole and its quantum counterpart is formulated. The
thermodynamical quantities (energy, temperature, entropy) are calculated and
occur to be the same for both the classical and quantum-corrected black holes.
So, no quantum corrections to thermodynamics are observed. The possible
relevance of the results obtained to the four-dimensional case is discussed.Comment: Latex, 28 pges; minor corrections in text and abstract made and new
references adde
Can forest management based on natural disturbances maintain ecological resilience?
Given the increasingly global stresses on forests, many ecologists argue that managers must maintain ecological resilience: the capacity of ecosystems to absorb disturbances without undergoing fundamental change. In this review we ask: Can the emerging paradigm of natural-disturbance-based management (NDBM) maintain ecological resilience in managed forests? Applying resilience theory requires careful articulation of the ecosystem state under consideration, the disturbances and stresses that affect the persistence of possible alternative states, and the spatial and temporal scales of management relevance. Implementing NDBM while maintaining resilience means recognizing that (i) biodiversity is important for long-term ecosystem persistence, (ii) natural disturbances play a critical role as a generator of structural and compositional heterogeneity at multiple scales, and (iii) traditional management tends to produce forests more homogeneous than those disturbed naturally and increases the likelihood of unexpected catastrophic change by constraining variation of key environmental processes. NDBM may maintain resilience if silvicultural strategies retain the structures and processes that perpetuate desired states while reducing those that enhance resilience of undesirable states. Such strategies require an understanding of harvesting impacts on slow ecosystem processes, such as seed-bank or nutrient dynamics, which in the long term can lead to ecological surprises by altering the forest's capacity to reorganize after disturbance
A Conformally Invariant Holographic Two-Point Function on the Berger Sphere
We apply our previous work on Green's functions for the four-dimensional
quaternionic Taub-NUT manifold to obtain a scalar two-point function on the
homogeneously squashed three-sphere (otherwise known as the Berger sphere),
which lies at its conformal infinity. Using basic notions from conformal
geometry and the theory of boundary value problems, in particular the
Dirichlet-to-Robin operator, we establish that our two-point correlation
function is conformally invariant and corresponds to a boundary operator of
conformal dimension one. It is plausible that the methods we use could have
more general applications in an AdS/CFT context.Comment: 1+49 pages, no figures. v2: Several typos correcte
Seismology of the Sun : Inference of Thermal, Dynamic and Magnetic Field Structures of the Interior
Recent overwhelming evidences show that the sun strongly influences the
Earth's climate and environment. Moreover existence of life on this Earth
mainly depends upon the sun's energy. Hence, understanding of physics of the
sun, especially the thermal, dynamic and magnetic field structures of its
interior, is very important. Recently, from the ground and space based
observations, it is discovered that sun oscillates near 5 min periodicity in
millions of modes. This discovery heralded a new era in solar physics and a
separate branch called helioseismology or seismology of the sun has started.
Before the advent of helioseismology, sun's thermal structure of the interior
was understood from the evolutionary solution of stellar structure equations
that mimicked the present age, mass and radius of the sun. Whereas solution of
MHD equations yielded internal dynamics and magnetic field structure of the
sun's interior. In this presentation, I review the thermal, dynamic and
magnetic field structures of the sun's interior as inferred by the
helioseismology.Comment: To be published in the proceedings of the meeting "3rd International
Conference on Current Developments in Atomic, Molecular, Optical and Nano
Physics with Applications", December 14-16, 2011, New Delhi, Indi
Optimal resource allocation for multi-queue systems with a shared server pool
We study optimal allocation of servers for a system with multiple service facilities and
with a shared pool of servers. Each service facility poses a constraint on the maximum
expected sojourn time of a job. A central decision maker can dynamically allocate servers
to each facility, where adding more servers results in faster processing speeds but against
higher utilization costs. The objective is to dynamically allocate the servers over the
different facilities such that the sojourn-time constraints are met at minimal costs. This
situation occurs frequently in practice, e.g., in Grid systems for real-time image processing
(iris scans, fingerprints). We model this problem as a Markov decision process and derive
structural properties of the relative value function. These properties, which are hard to
derive for multi-dimensional systems, give a full characterization of the optimal policy.
We demonstrate the effectiveness of these policies by extensive numerical experiments
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