2,862 research outputs found
Factors influencing the downstream transport of sediment in the Lough Feeagh catchment, Burrishoole, Co. Mayo, Ireland
Research laboratories in the Burrishoole catchment have been the focus of salmonid research since 1955. One aspect of the research has been to monitor the number of salmon and sea trout migrating to sea as smolts and returning to the catchment as adults. In the early 1990s it became clear that the smolt output from the catchment had declined over the previous two decades. At about the same time the presence of fine particles of peat silt in the hatchery became increasingly apparent and led to a higher incidence of mortality of young fry. These observations and management difficulties led to a study of silt transport in the surface waters of the catchment, which is described in this article. The authors describe geology, soils, climate and hydrology of Burrishoole before examining the sediment deposition in Lough Feeagh
OPTIMISATION OF THE INDUCTIVELY-COUPLED PLASMA FOR THE ANALYSIS OF SOLUTIONS AND SLURRIES
The application of inductively-coupled plasma (ICP) spectrometry for
the analysis of solutions and slurries is reviewed. The critical
parameters which affect analytical performance are identified and
methods for the optimisation of the ICP for such applications
demonstrated.
Particle size of the suspended sample is shown to be the most
important factor in the analysis of slurry samples. It is demonstrated
that only particles less than 8 um in diameter reach the plasma even
when the maximal diameter injector tube (3 mm i.d.) is used.
Accordingly various methods for the reduction of particle size have
been investigated and milling shown to be the preferable approach. A
low cost method using blown zirconia spheres in a screw-cap plastic
bottle agitated on a flask shaker was developed. Using this method it
proved possible to analyse a wide variety of solid samples using slurry
atomisation using both ICP- atomic emission spectrometry (ICP-AES)
and ICP-mass spectrometry (ICP-MS) with aqueous calibration.
Results are presented for the elemental analysis of certified reference
material (CRM) soils, catalyst samples, a zeolite, titanium dioxide,
P.T.F.E. powder, and unfiltered natural waters by slurry atomisation
ICP-AES.
Comparison by other techniques showed excellent accuracy for major,
minor and trace elements and equivalent precision to solution analysis.
The CRM soils, catalysts and the zeolite were also analysed by ICP-MS
using slurry atomisation with similar success and enhanced accuracy at
the trace level. Aluminium proved to be an exception and generally
low recoveries (80-90%) were observed for this element using slurry
atomisation.
Finally the uses of the simplex optimisation algorithm to improve
analytical performance, particularly in ICP-AES, is discussed. A
computer program to facilitate the use of simplex optimisation for a
variety of instrumentation was written and its use in three different
analytical techniques demonstrated.
The necessary hardware and software modifications to a commercially
available ICP spectrometer to enable automated simplex optimisation
are described. The prospects for such intelligent self-optimising
instrumentation are discussed as is the potential extension of the
application of slurry analysis by ICP-AES and ICP-MS.ICI Mond Division,Research and Technology Department, PO Box 8, The Heath, Runcorn, Cheshire WA7 4Q
Dense molecular gas: a sensitive probe of stellar feedback models
We show that the mass fraction of giant molecular cloud (GMC) gas (n ≳ 100 cm⁻³) in dense (n ≫ 10⁴ cm⁻³) star-forming clumps, observable in dense molecular tracers (L_(HCN)/L_(CO(1–0))), is a sensitive probe of the strength and mechanism(s) of stellar feedback, as well as the star formation efficiencies in the most dense gas. Using high-resolution galaxy-scale simulations with pc-scale resolution and explicit models for feedback from radiation pressure, photoionization heating, stellar winds and supernovae (SNe), we make predictions for the dense molecular gas tracers as a function of GMC and galaxy properties and the efficiency of stellar feedback/star formation. In models with weak/no feedback, much of the mass in GMCs collapses into dense subunits, predicting L_(HCN)/L_(CO(1–0)) ratios order-of-magnitude larger than observed. By contrast, models with feedback properties taken directly from stellar evolution calculations predict dense gas tracers in good agreement with observations. Changing the strength or timing of SNe tends to move systems along, rather than off, the L_(HCN)–L_(CO) relation (because SNe heat lower density material, not the high-density gas). Changing the strength of radiation pressure (which acts efficiently in the highest density gas), however, has a much stronger effect on L_(HCN) than on L_(CO). We show that degeneracies between the strength of feedback, and efficiency of star formation on small scales, can be broken by the combination of dense gas, intermediate-density gas and total star formation rate (SFR) tracers, and favour models where the galaxy-integrated star formation efficiency in dense gas is low. We also predict that the fraction of dense gas (_(LHCN)/L_(CO(1–0))) increases with increasing GMC surface density; this drives a trend in L_(HCN)/L_(CO(1–0)) with SFR and luminosity which has tentatively been observed. Our results make specific predictions for enhancements in the dense gas tracers in unusually dense environments such as ultraluminous infrared galaxies and galactic nuclei (including the galactic centre)
The interaction of perception, production and spelling on the vowel performance of ESL students
How can a contemporary composer use film to enhance music?
There is a body of literature on music in film, and some analytical writing on music video, but almost no writing that approaches the subject from the point of view of how the film might support the music. My research question is, therefore, how can moving images help a composer to communicate music to an audience?
To resolve this question I first analysed a number of key music/film works and formulated a hypothesis that there are five modes where film can support music. These are by
• First Mode: creating an ambience conducive to the appreciation of music
• Second Mode: using filmic tools such as editing and camerawork to emphasise musical elements
• Third Mode: supplying context about the work and its creation
• Fourth Mode: embedding the music in a format that facilitates the music’s appreciation
• Fifth Mode: embedding the music into the narrative structure of the film.
To explore this hypothesis I created three music/film artworks that utilised the techniques above. These were a video installation, a film that creates a supportive ambience for a set of piano nocturnes, and a feature length music documentary that features a number of music videos.
In the conclusion I will state that through these works I have shown that these five modes do indeed enable film to support music
Use of space by laying hens: social and environmental implications for free-range systems
The use of space by laying hens in free-range systems is often very uneven, with
birds displaying an apparent reluctance to leave (and move away from) the house.
Using mainly small groups as models for the larger flocks normally housed in
commercial free-range systems, the role of various social and environmental factors
concerning hens' movement and use of space were investigated in this thesis.Hens displayed a greater readiness to emerge from a familiar covered box into
an unfamiliar outdoor area when the outdoor area contained familiar feeders, even
though the birds had free access to food in their home pens. Emergence latencies
decreased with repeated testing. Birds also spent more time in the outdoor area when
feeders were present, though they tended not to move past the feeder which was
nearest the box. Birds which had been exposed to an enriching stimulus (traffic cones)
in their home pens tended to leave the box earlier than those which had not, though
this was not dependent on the actual presence of cones in the outdoor area. This
suggests that a more complex home environment can influence birds' responses to
novel environments. Furthermore, the order of emergence into the paddock was not
significantly influenced by social rank. Birds which had been regularly exposed to the
outside environment during the rearing process displayed little or no fear of the
outdoor area as adults. In contrast, regular handling had little effect on birds' readiness
to enter the outdoor area. Regular exposure to the outside environment also reduced
birds' underlying fearfulness (measured by tonic immobility), both in small
experimental groups and in a larger free-range flock. Individual birds from small
groups or from single cages took longer to move past unfamiliar birds than they did to
move past familiar birds (even those of higher rank), and took longer to move past an
increasing number of unfamiliar birds. However, birds in a free-range house
displayed a wide range of movements, and very little aggression, suggesting that any
inhibition of movement within the house was not due to "pecking pressure" from other
birds. Birds displayed greater readiness to enter into and disperse in the outdoor area
when other birds were already present in the area. This was not dependent on the
familiarity of birds in the outdoor area. A larger number of birds in the outdoor area
increased the attractiveness of the outdoor area to other birds. The introduction of
cover into an outside area had a limited effect on increasing the attractiveness of the
outdoor area to domestic fowl, though this was not reflected in the birds' vigilance
behaviour. It was concluded that birds find the outside environment aversive due to its
fear-evoking properties (such as the fear of predation), and to the large discrepancy
between the inside and outside environments. Possible implications of the present
findings for free-range systems are discussed
The development impact of the illegality of drug trade
This paper reviews the unintended consequences of the war on drugs, particularly for developing countries, and weighs them against the evidence regarding the efficacy of prohibition to curb drug use and trade. It reviews the available evidence and presents new results that indicate that prohibition has limited effects on drug prevalence and prices, most likely indicating a combination of inelastic drug demand (due to its addictive properties) and elastic supply responses (due to black markets). This should turn the focus to the unintended consequences of drug prohibition. First, the large demand for drugs, particularly in developed countries, generates the possibility of massive profits to potential drug providers. This leads to the formation of organized crime groups, which use violence and corruption as their means of survival and expansion and which, in severe cases, challenge the state and seriously compromise public stability and safety. Second, prohibition and its derived illegal market impose greater costs on farmers than on drug traffickers. In many instances, this entails the transfer of wealth from poor peasants to rich (and ruthless) traders. Third, criminalization can exacerbate the net health effects of drug use. These consequences are so pernicious that they call for a fundamental review of drug policy around the world.Health Monitoring&Evaluation,Crime and Society,Economic Theory&Research,Post Conflict Reconstruction,Markets and Market Access
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