11,804 research outputs found
Evaluation of the application of ERTS-1 data to the regional land use planning process
The author has identified the following significant results. Employing simple and economical extraction methods, ERTS can provide valuable data to the planners at the state or regional level with a frequency never before possible. Interactive computer methods of working directly with ERTS digital information show much promise for providing land use information at a more specific level, since the data format production rate of ERTS justifies improved methods of analysis
On Farm Riparian Grazing Demonstration
Two farm demonstrations were designed to show effects of periodic grazing of riparian areas. Sites were monitored for vegetative cover, degree of treading or hoof prints and dung deposition within three m of stream edge following grazing by beef cattle. A fenced enclosure was established along a 350 m stream reach on Farm-1, and eleven permanent stations were monitored following six graze periods over 12-months. Farm-2 involved grazing of two 0.13 ha paddocks, each of which contained a 22 m stream reach. On Farm-1 the cover improved following riparian exclusion, and evidence of treading in the 11 stations declined following each graze period. On Farm-2, vegetation was dense in the beginning, and one day graze periods with high stock density did not result in significant soil exposure, even though hoof prints were evident at more than 30% of the transect points. Having access to a drinking water tank 45 m up slope did not influence cover nor dung deposition in the riparian zone. The number of dung patties found within 3 m of the stream edge ranged from 15 to 28/100 m (Farm-1) and from 41 to 96/100 m (Farm-2). Estimates of potential dung N deposited within three m of the entire reach of the respective streams was 565 g and 83 g. This project showed ways to use riparian areas with minimal impact on its function
Goats to Control the Encroachment of Undesirable Brush and Woody Species in Cattle Pastures
Field studies were initiated in an abandoned, overgrown 8.4 ha orchard left untouched for 15 years to evaluate the effectiveness of using goats (Capra hircus hircus) to manage undesirable vegetation. Goats alone (G: 30 does/ha) or cattle (Bos taurus) with goats (GC:17 does/ha and 3 steers/ha) were mob-grazed twice a year during four grazing seasons. Multiflora rose (Rosa multiflora Thunb.) canopy area decreased from 12 to 2.5 m2 in grazed pastures and multiflora rose live canes were 100% in the control, 0% in G, and only 8% in GC at the completion of the study. Following two years of rest, cattle alone (C: 6 steers) or goats + cattle (GC: 9 goats and 6 steers) were rotationally grazed on the same site. Over four grazing seasons, brambles (Rubus spp.) and honeysuckle (Locifera japonica) vines were practically eliminated from grazed pastures. Multiflora rose bushes grew to a height of 1.8 m in C, but were kept low (avg .6 m) in GC (P \u3c 0.01). Similarly, multiflora rose canopy area was well controlled in GC (avg .5 m2), but increased to 7 m2 in C (P \u3c 0.03). Black locust (Robinia pseudoacacia L.) trees were browsed by goats and cattle and were practically eliminated from grazed pastures. Integrating goats into mountain grazing systems is a useful and environmentally-friendly management tool to keep these pastures in production
Gauges and Cosmological Backreaction
We present a formalism for spatial averaging in cosmology applicable to
general spacetimes and coordinates, and allowing the easy incorporation of a
wide variety of matter sources. We apply this formalism to a
Friedmann-LeMaitre-Robertson-Walker universe perturbed to second-order and
present the corrections to the background in an unfixed gauge. We then present
the corrections that arise in uniform curvature and conformal Newtonian gauges.Comment: 13 pages. Updated: reference added, typos corrected, exposition
clarified. Version 3: Replaced with version published by JCA
Spatial and Time Distribution of Dairy Cattle Manure in an Intensive Pasture System
This study determined distribution of feces and urine from dairy cattle managed in a rotationally grazed pasture. Lactating Holsteins (n=18) and Jerseys (n=18) were grazed on a .74 ha endophyte-free fescue (Festuca arundinacea)/white clover (Trifolium repens) pasture. All cows were constantly observed for 24 h 6 times over 12 mo. Cows had access to about 54% of the paddock during the first grazing period (12 h) and had access to the entire paddock during the second grazing period (8 h). Data included: (1) all feces and urine events from eight cows, observed while in the pasture, feed area, milking parlor or in transit; and (2) all urine and feces events on pasture for all 36 cows each grazing period. After each grazing period, urine (marked with color coded flags) and feces were surveyed and mapped. Data were transformed and then analyzed using statistical software. Percentages of the manure events were highly correlated with time spent in each area (r= .99). Feces and urine (estimated at .12 m2 and .36 m2, respectively) from the six 24-hr observations covered 10% of the total paddock. Within a 30-m radius of the water tank, spatial density of feces and urine from the warm season observations (July, August, September) were significantly greater than concentrations during the cool season observations (December, February, and April). Pasture systems can potentially reduce manure handling and storage requirements proportional to the time cows are kept on pasture. Manure on pasture was relatively evenly distributed over multiple grazing periods
Generalized BF Theory in Superspace as Underlying Theory of 11D Supergravity
We construct a generalized BF theory in superspace that can embed
eleven-dimensional supergravity theory. Our topological BF theory can
accommodate all the necessary Bianchi identities for teleparallel superspace
supergravity in eleven-dimensions, as the simplest but nontrivial solutions to
superfield equations for our superspace action. This indicates that our theory
may have solutions other than eleven-dimensional supergravity, accommodating
generalized theories of eleven-dimensional supergravity. Therefore our
topological theory can be a good candidate for the low energy limit of
M-theory, as an underlying fundamental theory providing a `missing link'
between eleven-dimensional supergravity and M-theory.Comment: 16 pages, latex, two new paragraphs in section 4 and in Concluding
Remarks with two new reference
Multi-objective improvement of software using co-evolution and smart seeding
Optimising non-functional properties of software is an important part of the implementation process. One such property is execution time, and compilers target a reduction in execution time using a variety of optimisation techniques. Compiler optimisation is not always able to produce semantically equivalent alternatives that improve execution times, even if such alternatives are known to exist. Often, this is due to the local nature of such optimisations. In this paper we present a novel framework for optimising existing software using a hybrid of evolutionary optimisation techniques. Given as input the implementation of a program or function, we use Genetic Programming to evolve a new semantically equivalent version, optimised to reduce execution time subject to a given probability distribution of inputs. We employ a co-evolved population of test cases to encourage the preservation of the program’s semantics, and exploit the original program through seeding of the population in order to focus the search. We carry out experiments to identify the important factors in maximising efficiency gains. Although in this work we have optimised execution time, other non-functional criteria could be optimised in a similar manner
Polyakov loop correlators from D0-brane interactions in bosonic string theory
In this paper we re-derive the effective Nambu-Goto theory result for the
Polyakov loop correlator, starting from the free bosonic string and using a
covariant quantization. The boundary conditions are those of an open string
attached to two D0-branes at spatial distance R, in a target space with compact
euclidean time. The one-loop free energy contains topologically distinct
sectors corresponding to multiple covers of the cylinder in target space
bordered by the Polyakov loops. The sector that winds once reproduces exactly
the Nambu-Goto partition function. In our approach, the world-sheet duality
between the open and closed channel is most evident and allows for an explicit
interpretation of the free energy in terms of tree level exchange of closed
strings between boundary states. Our treatment is fully consistent only in
d=26; extension to generic d may be justified for large R, and is supported by
Montecarlo data. At shorter scales, consistency and Montecarlo data seem to
suggest the necessity of taking into account the Liouville mode of Polyakov's
formulation.Comment: 17 pages, 4 figures, minor corrections, a few references added,
version accepted for publication in JHE
On minimal coupling of the ABC-superparticle to supergravity background
By rigorous application of the Hamiltonian methods we show that the
ABC-formulation of the Siegel superparticle admits consistent minimal coupling
to external supergravity. The consistency check proves to involve all the
supergravity constraints.Comment: 8 pages RevTex file, to appear in Phys. Rev.
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