1522 research outputs found
Sort by
Estimating the size and structure of Pine Marten populations using non-invasive genetic sampling
Get PDFThe pine marten is one of six mustelid species currently established in Ireland along with the badger, otter, stoat, ferret and the American mink. The ancient origin of the Irish pine marten is unknown but it was possibly introduced into Ireland in the Bronze Age as a commodity species for its luxurious pelt. The species was legally protected in Ireland in 1976 after centuries of persecution with the extensive deforestation of the island and hunting for fur or predator control. The current conservation status is considered to be favourable as the population seems to be expanding its range from core populations in the mid-west, midlands and the south-east of the country. However, the status of these core populations has not been assessed and is very difficult to evaluate based on traditional survey methods. This study aimed to develop the methods required to census pine marten populations based on non-invasive genetic sampling of hair and faeces.
Real-time PCR methods which enabled rapid species and sex identification of non-invasively collected samples were developed based on either the hybridisation of species or sex specific probes, or on differences in melting-temperature between amplified DNA sequences of less than 150 nucleotides in length. Genetic variability of the Irish population was assessed at 20 microsatellite loci. The number of alleles per locus (2.29) and expected heterozygosity (0.35) were low and a significant bottleneck signature was detected using a set of 41 road-kill individuals. The historical decline in pine marten distribution and abundance in Ireland has therefore had an impact on genetic diversity. Despite this no significant structuring was identified between regions, suggesting the dispersal ability of the pine marten is sufficient to maintain a panmictic population.
A census of two populations in south-east Ireland was then conducted by non-invasive genetic sampling of hair and scats using the methods developed in the project. Species and sex identification success rates were high for both sample types (88-100%), but individual identification was more reliable with plucked hair (94%) than scats (38%). Nine individual pine marten were identified in total in between the two sites by genotyping hair samples with eight microsatellite loci. Independent live trapping surveys carried out after the non-invasive census validated the genetic approach as the same individuals were captured with both survey methods.
Remotely plucked hair genotyping is a powerful and non-invasive survey method which can be used to inventory the magnitude and distribution of genetic diversity in pine marten, and other species with similar life history such as the stone marten, to identify any potentially important populations towards which conservation resources should be targeted in the future
Lethal and sub-lethal effects of ivermectin on north temperate dung beetles, Aphodius ater and Aphodius rufipes (Coleoptera: Scarabaeidae)
Get PDFIvermectin is an anthelmintic veterinary medicine, and is excreted in the dung of treated livestock in a mainly unmetabolised form. Ivermectin is known to have toxic effects on dung beetles, but most studies to date have been conducted on tropical and sub-tropical species. Relatively few laboratory studies have focused on the specific effects of ivermectin on survival and development of north temperate dung beetles. In this study, we experimentally investigated the effect of ivermectin concentration on various life stages of two Aphodius dung beetle species. Dung was collected from cattle groups that had been treated with a subcutaneous injection of ivermectin. Laboratory bioassays were conducted by feeding adults of two beetle species (Aphodius ater and Aphodius rufipes) with dung that contained different concentrations of ivermectin. Adult survival and oviposition were measured, and the subsequent development and survival of produced larvae was monitored over time. Larval development rates were significantly slowed by ivermectin. Ivermectin had significant negative effects on the survival of larvae. Overall, ivermectin concentration caused large and significant reductions in the cohort size from an individual dung pat that would potentially contribute to the next generation of beetles. In general, ivermectin concentration did not have significant negative effects on adult survival. The number of eggs per female A. rufipes was significantly reduced by ivermectin concentration in one of two bioassays, but the magnitude of the effect was not large. The actual impacts on dung beetle population dynamics in farmland would depend on several other factors, which are discussed
Refractive index dynamics of quantum dot based waveguide electroabsorbers
Get PDFThe refractive index dynamics of InAs/GaAs quantum dot based waveguide absorbers is studied using heterodyne pump-probe measurements. Absorption reduction due to the pump can be accompanied by either positive or negative refractive index changes depending on the wavelength used. This change in sign of the phase amplitude coupling can be understood by considering the atomlike nature of the quantum dot transitions involved. (C) 2010 American Institute of Physics. [doi:10.1063/1.3476347
Beam properties of injection profiled quantum dot lasers
Get PDFThe impact of injection current profiling on the spatial mode structure of quantum dot semiconductor lasers is investigated. Numerical simulations based on a spatial extension of a simple rate equation model for quantum dot devices reveal the role of non-resonant carries in the appearance of strong dips in the optical field of the device. Symmetry breaking may also occur whereby the position of the dip shifts from the centre of the injection region. (C) 2010 Elsevier B.V. All rights reserved
RETHINKING INNOVATION POLICY IN IRELAND: A CRITICAL CRITIQUE
Get PDFPrior to the current economic recession, the Irish government has been championing an innovation agenda. However, national and European reports and metrics paint a mixed picture about Ireland’s engagement in and outputs derived from innovation activities. Therefore, a critique of Irish innovation policy is timely and relevant given the renewed emphasis and restricted budgetary support afforded to create new enterprises, markets, export opportunities and employment growth. In short, where innovation policy traditionally focused on funding future opportunities and capacities, micro and macroeconomic forces now requires innovation policy to be responsive to current enterprise difficulties. Through incorporating innovation policy priorities, funding streams and key policy stakeholders we find that there is an imbalance in Irish innovation policy with a legacy of prioritising and funding ‘hard’ science and technology based innovations while ignoring ‘softer’ aspects of innovation i.e. service products, business models and customer/delivery interfaces at a similar level which can be implemented at all enterprise levels, incur less costs and operationalised in a more timely manner. This policy disparity has serious consequences for our progressive innovation ambitions around entrepreneurship, scaling indigenous enterprises, creating and sustaining SME’s. The paper identifies that there is a paramount need to rethink innovation policy in order to reap the rewards of our previous and on-going investments towards achieving our national innovation goals and ambitions. To conclude we provide a roadmap for rethinking this policy around widening innovation concepts, improving SMEs capacity to innovative and addressing the academic-industry applied research and collaboration gaps
Impact of wildfire intensity and logging on fungal and nitrogen-cycling bacterial communities in British Columbia forest soils
No full textWildfire and logging are common disturbances in the forests of northwestern North America, causing changes in soil chemistry and microbiology, including fungal and nitrogen-cycling bacterial communities. These organisms play key roles in nutrient cycling, and affect the regeneration of tree seedlings after disturbance. We studied the effects of wildfire and logging on fungal and nitrogen-cycling communities in the rhizosphere of 16 month-old Douglas-fir seedlings as they regenerated in burned and logged soils. Seeds were planted against root windows that were set up vertically in the soil, with a removable front panel used to access the seedling rhizosphere soil surface. Windows were established in control, lightly burned, and severely burned plots, as well as two types of logged plots (clearcut and screefed clearcut). Soil scrapings from the root window–soil interface were taken and the structure of fungal and nitrogen-cycling communities was resolved using length-heterogeneity PCR (LH-PCR) of fungal nuclear ribosomal RNA genes, and terminal restriction fragment length polymorphism (T-RFLP) analysis of nifH and nosZ genes. We found striking differences in the community structure of fungal, denitrifying, and N-fixing communities in response to burning and logging. With the exception of clearcut and screefed clearcut, which were generally similar, each treatment had a unique impact on community structure for these genes. Burning and logging also impacted the relative richness and evenness of these communities. Fungal relative richness and evenness increased in response to logging and severe burning, while denitrifier relative richness and evenness increased in all disturbance treatments, and N-fixing bacterial relative richness and evenness decreased in response to burning. The greatest differences in microbial community structure, relative richness, and evenness were found in the comparisons of lightly burned and logged treatments. The results suggest that the presence of an intact forest floor influences soil microbial communities less than the presence of living trees
Probabilistic Fault Diagnosis in the MAGNETO Autonomic Control Loop
Get PDFManagement of outer edge domains is a big challenge for service providers due to the diversity, heterogeneity and large amount of such networks, together with limited visibility on their status. This paper focuses on the probabilistic fault diagnosis functionality developed in the MAGNETO project, which enables finding the most probable cause of service problems and thus triggering appropriate repair actions. Moreover, its self-learning capabilities allow continuously enhancing the accuracy of the diagnostic
process
Active for a day Physical activity relapes and strategies for maintenance following participation in a mass event
Get PDFDebate exists about the potential public health benefits of mass community events that encourage participation in physical activity. There have been few previous attempts to investigate their impact on the behaviour of participants, and the rates of relapse following the event. The aim of the research in this thesis was (i) to describe participants in three women-only mass participation events in Ireland (N = 82,955), (ii) to identify relapsers who regressed from sufficiently to insufficiently active in the months following the event, and (iii) to recruit these individuals to trials to re-initiate participation in physical activity.
International Physical Activity Questionnaire (IPAQ) physical activity self report data were collected before and after the events and relapse (n=852) was defined as decreasing participation by at least 60 minutes and regressing from the high or moderate IPAQ category to low active. Subsequently, in 2007, 176 women participated in a minimal contact randomised controlled trial (RCT) while in 2008, 395 women were recruited to a cluster RCT, which promoted existing resources for physical activity in the community.
The majority of women participated for altruistic reasons and to have fun. Thus, the events motivated more than the „habitual exerciser‟ to participate. Approximately 11% of participants were classified as relapsers and any contact appeared sufficient to re-stimulate physical activity. In both trials, all participants reported significant increases in physical activity, with no between group difference. In the cluster RCT, intervention participants reported a significant increase in vigorous intensity activity. Aspects of the latter have been adopted by agencies tasked with promoting physical activity in Ireland.
Mass events could be used as an initial prompt for physical activity even among sedentary women. Providing reinforcement strategies after events that utilise existing opportunities for physical activity and that adopt a “non fitness” approach, could contribute to public health physical activity promotion efforts
An investigation into the spatial profile of macular pigment
Get PDFINTRODUCTION
The macula is the central region of the retina and is responsible for sharpest visual
acuity. At the center of the macula, the carotenoids lutein (L), zeaxanthin (Z), and
meso-Z, are concentrated, where they are collectively referred to as macular pigment
(MP). MP acts as a filter of short-wavelength (blue) light and is a powerful antioxidant.
Age-related macular degeneration (AMD) is the leading cause of blindness in the
western world. AMD is believed to be caused by cumulative and chronic insult from
reactive oxygen intermediates (ROIs), which are mainly generated from oxygen
metabolism and short-wavelength (blue) light exposure. MP is believed to protect
against AMD due to its short-wavelength (blue) light filtering and antioxidant
properties.
OBJECTIVES
This PhD thesis was designed to:
1) Investigate the reproducibility of the MP spatial profile using customised
heterochromatic flicker photometry (cHFP), and to relate the MP spatial profile
to foveal architecture (Study One).
2) Investigate the relationship between specific MP spatial profile types and risk
factors for AMD (Study Two).
3) Investigate if weight loss is associated with changes in serum concentrations of
L and Z, and/or macular pigment optical density (MPOD) (Study Three).
METHODS
Study One: The Spatial Profile of Macular Pigment and its Relationship with
Foveal Architecture
We recruited 16 healthy subjects (nine had the typical exponential MP spatial profile
[Group 1]; seven had a secondary peak MP spatial profile [Group 2]). MP spatial
xxv
profile was measured using cHFP on three separate occasions. Six radiance
measurements were obtained at each locus (0.25º, 0.5º, 1º, and 1.75º eccentricity;
reference point: 7º). Foveal architecture was assessed by optical coherence tomography
(OCT).
Study Two: The Spatial Profile of Macular Pigment and its Relationship with Risk
Factors for AMD
The MP spatial profile of 484 healthy subjects was measured using cHFP and
categorised into one of two profile types (typical exponential or atypical ‘central dip’).
Data on risk factors for AMD were obtained using a general health and lifestyle
questionnaire. Dietary intake of L and Z were assessed using a validated food
frequency questionnaire (FFQ). Serum concentrations of L and Z were also assessed
using high performance liquid chromatography (HPLC).
Study Three: Changes in MPOD and serum concentrations of L and Z in response
to weight loss
We recruited 104 overweight subjects into this randomised-controlled weight loss study.
For the intervention group (I group, n = 54), weight was assessed weekly and body
composition, including body fat (kg and percentage body fat) were assessed at baseline,
six and 12 months using dual energy x-ray absorbtiometry (DEXA). Weight loss was
encouraged using dietary and exercise programmes. MPOD was measured by cHFP
and serum concentrations of L and Z by HPLC (at baseline, one, three, six and 12-
months). The control group (C group, n = 50) were assessed at baseline and 12-months.
RESULTS
Study One: The Spatial Profile of Macular Pigment and its Relationship with
Foveal Architecture
Subjects who had the typical decline profile still had this profile after averaging
repeated measures (Group 1). Subjects who had a secondary peak displayed the
secondary peak after averaging repeated measures (Group 2). Mean SD foveal width,
Group 1 was significantly narrower than mean SD foveal width, Group 2 (1306 ± 240
xxvi
µm and 1915 ± 161 µm, respectively; p < 0.01). This difference remained after
controlling for sex (p < 0.001). Foveal width was significantly related to mean foveal
MP, controlling for sex (r = 0.588, p = 0.021). Foveal profile slope was significantly
related to MP spatial profile slope, following removal of an outlier (r = 0.591, p =
0.020).
Study Two: The Spatial Profile of Macular Pigment and its Relationship with Risk
Factors for AMD
The presence of the ‘central dip’ MP spatial profile was significantly more common in
older subjects (p = 0.004) and in current cigarette smokers, (p = 0.031). Also, there was
a significant age-related decline in central MPOD (0.25° retinal eccentricity), but in
males only (r = -0.146, p = 0.049).
Study Three: Changes in MPOD and serum concentrations of L and Z in response
to weight loss
Repeated measures analysis of variance (RM ANOVA) demonstrated significant weight
loss in the I group over the study period (p = 0.000). There was no significant weight
change in the C group (p = 0.993). RM ANOVA of dietary L and Z, serum L and Z,
and MPOD demonstrated no significant time, or time/group interaction, effect in any of
these parameters (p > 0.05, for all), with the exception of a significant decrease in
dietary intake of Z seen in both groups, over the study period (p < 0.05). There was a
positive and significant relationship between body fat loss (kg) and increase in serum
concentrations of L in the I group (r = 0.521, p = 0.006).
CONCLUSIONS
Study One: The Spatial Profile of Macular Pigment and its Relationship with
Foveal Architecture
Customised HFP reproducibly measures MP spatial profile. Secondary peaks seen in
the MP spatial profile cannot be attributed to measurement error, and are associated
with wider foveas. The slope of an individual’s MP spatial profile is related to foveal
slope, with a steeper MP distribution seen with a steeper foveal depression.
xxvii
Study Two: The Spatial Profile of Macular Pigment and its Relationship with Risk
Factors for AMD
A ‘central dip’ in the MP spatial profile, seen in older subjects, and in cigarette
smokers, is likely to be an undesirable feature of macular pigmentation, and one which
may reflect increased risk of AMD. Further research is needed in this area.
Study Three: Changes in MPOD and serum concentrations of L and Z in response
to weight loss
Our finding that a reduction in body composition (e.g. fat mass) is related to increases in
serum concentrations of L is consistent with the hypothesis that body fat acts as a
reservoir for this carotenoid, and that weight loss can positively influence circulating
carotenoid levels
A Meta-Learning Method for Concept Drift
Get PDFThe knowledge hidden in evolving data may change with time, this issue is known as concept drift. It often causes a learning system to decrease its prediction accuracy. Most existing techniques apply ensemble methods to improve learning performance on concept drift. In this paper, we propose a novel meta learning approach for this issue and develop a method: Multi-Step Learning (MSL). In our method, a MSL learner is structured in a recursive manner, which contains all the base learners maintained in a hierarchy, ensuring the learned concepts are traceable. We evaluated MSL and two ensemble techniques on three synthetic datasets, which contain a number of drastic concept drifts. The experimental results show that the proposed method generally performs better than the ensemble techniques in terms of prediction accuracy