1,244 research outputs found
New Zealand Calanoid Copepod Invasions: Has Artificial Lake Construction Facilitated Invasions, and are our Coastal Waters Uninvaded?
Non-indigenous species have become a global issue of increasing importance in recent years, with many causing significant environmental and economic damage. Identifying locations vulnerable to invasion allows for focus of management efforts towards prevention of invasions at those locations. In order to determine whether constructed water bodies, such as reservoirs, ornamental lakes or retired mines, are more easily invaded environments than natural water bodies, owing to decreased biotic resistance, the distributions of native and non-indigenous freshwater calanoid copepod species in the North Island were examined. Calanoid copepods in ports and other coastal environments were also examined, in order to determine whether ports are more frequently invaded owing to increased propagule supplies from visiting ships and other sources.
The distributions of the native freshwater calanoid copepod species Boeckella hamata, B. propinqua, B. delicata and B. tanea are confined in the North Island of New Zealand to specific technostratigraphic terranes when natural waters only are examined, and as such each species can be considered to have a native range. The recently colonised calanoid copepod species Boeckella minuta (6 locations), Skistodiaptomus pallidus (3 locations) and Sinodiaptomus valkanovi (2 locations) are to date confined to constructed water bodies. Boeckella symmetrica (2 locations) may be confined to constructed water bodies, but the status of one location is unclear. Boeckella triarticulata, a species common in the South Island, is known only from a single farm dam in the North Island. The native species Boeckella hamata, B. propinqua and B. delicata were found to occur in constructed waters, but only B.
propinqua was found in constructed water bodies outside their natural ranges (9 locations). Calamoecia lucasi is found in lakes throughout most of the North Island, and is not confined to any one terrane. My results indicate that constructed water bodies are more easily invaded by non-indigenous species than natural water bodies, represents a potential pathway for future invaders to establish, and provides locations for species to spread.
In order to determine whether recently established freshwater calanoid copepod species have the potential to spread from their present habitats into other water bodies, the prosomal lengths of non-indigenous calanoid copepod species were measured and compared with those for native species. The results suggest that dietary overlap should prevent the non-indigenous species present to date from spreading into any water bodies with established Boeckella populations, although Sinodiaptomus valkanovi and Boeckella triarticulata could potentially spread to lakes containing only Calamoecia lucasi. Data on the co-occurrences of native freshwater calanoid copepod species support the theory of dietary exclusion, as Boeckella species have not been found to coexist.
In order to test whether New Zealand marine environments have been invaded by non-indigenous calanoid copepods, and whether ports have been more regularly invaded than non-port areas, calanoid copepods were sampled from various coastal locations around the North Island. With the possible exception of Sulcanus conflictus, no non-indigenous species were found, indicating that non-indigenous marine calanoid copepod species are not establishing in New Zealand despite a history of invasion elsewhere
Teacher Professional Development: A Primer for Parents and Community Members
Quality teachers are the single greatest determinant of student achievement. Teacher education, ability, and experience account for more variation in student achievement than all other factors. Studies have found that 40 to 90 percent of the difference in student test scores can be attributed to teacher quality. Knowing the subject matter, understanding how students learn, and practicing effective teaching methods translate into greater student achievement. Therefore, it is vitally important that teachers be well prepared when they begin teaching and that they continue to improve their knowledge and skills throughout their careers
Three-graviton scattering in Matrix theory revisited
We consider a subset of the terms in the effective potential describing
three-graviton interactions in Matrix theory and in classical
eleven-dimensional supergravity. In agreement with the results of Dine and
Rajaraman, we find that these terms vanish in Matrix theory. We show that the
absence of these terms is compatible with the classical supergravity theory
when the theory is compactified in a lightlike direction, resolving an apparent
discrepancy between the two theories. A brief discussion is given of how this
calculation might be generalized to compare the Matrix theory and supergravity
descriptions of an arbitrary 3-body system.Comment: 9 pages, LaTeX; v2: reference added, v3: text unchanged, Note added
clarifying connection with other recent result
BBC pay: we need equality all the way down - not just for the elite
Firms like the BBC can only afford to offer 'top talent' huge financial rewards by controlling costs down below, writes Mark Bank
Conservation of Supergravity Currents from Matrix Theory
In recent work by Kabat and Taylor, certain Matrix theory quantities have
been identified with the spatial moments of the supergravity stress-energy
tensor, membrane current, and fivebrane current. In this note, we determine the
relations between these moments required by current conservation, and prove
that these relations hold as exact Matrix Theory identities at finite N. This
establishes conservation of the effective supergravity currents (averaged over
the compact circle). In addition, the constraints of current conservation allow
us to deduce Matrix theory quantities corresponding to moments of the spatial
current of the longitudinal fivebrane charge, not previously identified.Comment: 11 pages, LaTeX, typos correcte
Ammonia removal in anaerobic digestion by biogas stripping: an evaluation of process alternatives using a first order rate model based on experimental findings
The feasibility of biogas stripping to remove ammonia in the anaerobic digestion of source segregated food waste was investigated. It was found in batch experiments that ammonia could be removed from digestate and that the removal followed 1st order kinetics with respect to total ammonia nitrogen concentration. Increasing temperature, biogas flow rate and initial pH all increased removal rates. Using kinetic data gathered in these experiments allowed the integration of ammonia stripping with an anaerobic digestion plant to be modelled for different configurations. Four scenarios were identified: post digestion, in situ, side-stream and pre-digestion ammonia removal relating to where in the process the ammonia stripping was performed. The modelling showed that in situ ammonia removal may be best able to reduce in-digester ammonia concentrations over a wide range of organic loading rates whereas pre-digestion showed most promise in terms of application due to the flexibility to control each part of the process separately. Further experimental work is required into these scenarios to confirm their viability
Using TPA to count linear extensions
A linear extension of a poset is a permutation of the elements of the set
that respects the partial order. Let denote the number of linear
extensions. It is a #P complete problem to determine exactly for an
arbitrary poset, and so randomized approximation algorithms that draw randomly
from the set of linear extensions are used. In this work, the set of linear
extensions is embedded in a larger state space with a continuous parameter ?.
The introduction of a continuous parameter allows for the use of a more
efficient method for approximating called TPA. Our primary result is
that it is possible to sample from this continuous embedding in time that as
fast or faster than the best known methods for sampling uniformly from linear
extensions. For a poset containing elements, this means we can approximate
to within a factor of with probability at least using an expected number of random bits and comparisons in the poset
which is at most Comment: 12 pages, 4 algorithm
The evolution of law enforcement : the generational differences of the new police officer and how to attract them to your agency
The primary purpose of this study was to enhance the knowledge of the generational differences in the law enforcement profession. With this knowledge, it is hopeful that, agencies will change their current recruiting strategies and gear them towards today\u27s new generation of law enforcement officer. The overall goal of this study was enlighten Henrico County and Chesterfield county administrators of concerns facing employee recruiting within law enforcement so proactive efforts can be taken to curb ineffective and outdated recruiting strategies and methods
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