1,881 research outputs found
Exploring the value of Scotland's environment
Protection of the environment can be regarded as representing a substantial cost to business. However, it is typically considered from the point of view of effect on company profitability, rather than its relative importance to human kind. This paper estimates the value of Scotland's natural environment by applying the methodology developed by Costanza et al (1997a and b) for estimation of the value of the earth's ecosystem services. Ecosystem services provide the vital functions to support life on Earth, such as flows of materials and energy. Since the study's publication, further research has sought to apply this global methodology to a regional and national level (for example Loomis et al, 2000, Farber and Griner, 2000 and Stevens et al, 2000). The value derived for Scotland provides a useful context for understanding the scale and importance of Scotland's natural habitats and it helps to reinforce the message that the environment is central to human welfare (Williams et al, 2003). The valuation of ecosystem services in monetary terms provokes theoretical, practical and philosophical arguments. This paper does not seek to revisit in depth these debates; rather the valuation should be taken as a starting point for setting the importance of Scotland's ecosystems in an interesting perspective. A recent edition of the journal Ecological Economics (Costanza and Farber, 2002) was devoted to considering some of these issues and providing many avenues for further exploration
On the relation between the Feynman paradox and Aharonov-Bohm effects
The magnetic Aharonov-Bohm (A-B) effect occurs when a point charge interacts
with a line of magnetic flux, while its dual, the Aharonov-Casher (A-C) effect,
occurs when a magnetic moment interacts with a line of charge. For the two
interacting parts of these physical systems, the equations of motion are
discussed in this paper. The generally accepted claim is that both parts of
these systems do not accelerate, while Boyer has claimed that both parts of
these systems do accelerate. Using the Euler-Lagrange equations we predict that
in the case of unconstrained motion only one part of each system accelerates,
while momentum remains conserved. This prediction requires a time dependent
electromagnetic momentum. For our analysis of unconstrained motion the A-B
effects are then examples of the Feynman paradox. In the case of constrained
motion, the Euler-Lagrange equations give no forces in agreement with the
generally accepted analysis. The quantum mechanical A-B and A-C phase shifts
are independent of the treatment of constraint. Nevertheless, experimental
testing of the above ideas and further understanding of A-B effects which is
central to both quantum mechanics and electromagnetism may be possible.Comment: 21 pages, 5 figures, recently submitted to New Journal of Physic
Citrus tristeza virus in Hawaii
This article describes the citrus tristeza virus in Hawaiâi, the pathogen, diseases and disease symptoms caused by the virus, insect vectors and transmission, diagnosis and detection, management, and quarantine, certification and suppression/eradication programs
Spartan Daily, January 9, 1950
Volume 38, Issue 54https://scholarworks.sjsu.edu/spartandaily/11320/thumbnail.jp
Structure of soot-containing laminar jet diffusion flames
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76650/1/AIAA-1993-708-697.pd
Role of turn-over in active stress generation in a filament network
We study the effect of turnover of cross linkers, motors and filaments on the
generation of a contractile stress in a network of filaments connected by
passive crosslinkers and subjected to the forces exerted by molecular motors.
We perform numerical simulations where filaments are treated as rigid rods and
molecular motors move fast compared to the timescale of exchange of
crosslinkers. We show that molecular motors create a contractile stress above a
critical number of crosslinkers. When passive crosslinkers are allowed to turn
over, the stress exerted by the network vanishes, due to the formation of
clusters. When both filaments and passive crosslinkers turn over, clustering is
prevented and the network reaches a dynamic contractile steady-state. A maximum
stress is reached for an optimum ratio of the filament and crosslinker turnover
rates.Comment: 17 pages, 8 figures, 5 supplementary movies (included in the source)
In the latest version, appendices D and E have been added, text has been
updated, Figure 2 has been corrected, and Figure 4 has been replaced by
simulation results with higher precisio
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