70 research outputs found
From nominal to true a posteriori probabilities: an exact Bayesian theorem based probabilistic data association approach for iterative MIMO detection and decoding
No full textIt was conventionally regarded that the existing probabilistic data association (PDA) algorithms output the estimated symbol-wise a posteriori probabilities (APPs) as soft information. In this paper, however, we demonstrate that these probabilities are not the true APPs in the rigorous mathematicasense, but a type of nominal APPs, which are unsuitable for the classic architecture of iterative detection and decoding (IDD) aided receivers. To circumvent this predicament, we propose an exact Bayesian theorem based logarithmic domain PDA (EB-Log-PDA) method, whose output has similar characteristics to the true APPs, and hence it is readily applicable to the classic IDD architecture of multiple-input multiple-output (MIMO) systems using the general M-ary modulation. Furthermore, we investigate the impact of the PDA algorithms' inner iteration on the design of PDA-aided IDD receivers. We demonstrate that introducing inner iterations into PDAs, which is common practice in PDA-aided uncoded MIMO systems, would actually degrade the IDD receiver's performance, despite significantly increasing the overall computational complexity of the IDD receiver. Finally, we investigate the relationship between the extrinsic log-likelihood ratio (LLRs) of the proposed EB-Log-PDA and of the approximate Bayesian theorem based logarithmic domain PDA (AB-Log-PDA) reported in our previous work. We also show that the IDD scheme employing the EB-Log-PDA without incorporating any inner PDA iterations has an achievable performance close to that of the optimal maximum a posteriori (MAP) detector based IDD receiver, while imposing a significantly lower computational complexity in the scenarios considered
Experimental and numerical investigation of the flexural behavior of one-way RC slabs strengthened with near-surface mounted and externally bonded systems
No full textThis study investigated the flexural performance of one-way reinforced concrete (RC) slabs strengthened with two distinct strengthening systems: near-surface mounted (NSM) bars and externally bonded (EB) carbon fiber-reinforced polymer (FRP) strips. The NSM bars comprised four types: carbon FRP (CFRP), basalt FRP (BFRP), glass FRP (GFRP), and stainless-steel (SS) bars. The NSM-strengthened slabs showcased substantial enhancements in yield and ultimate load capacity, ranging from 20 % to 55 % and 59-123 %, respectively. In comparison, those strengthened with EB-CFRP strips displayed increases from 46 % to 107 % and 45-177 %, respectively, depending on the axial stiffness ratio of the strengthening system provided. Furthermore, the slabs reinforced with NSM-BFRP bars showed an 11-25 % improvement in their ductility indices. In contrast, the slabs reinforced with EB experienced a decrease in ductility ranging from 38 % to 50 %. This reduction was attributed to the differences in the modes of failure observed in both strengthening systems. The rupture of the NSM-FRP bars and the strain readings associated at the end of testing confirmed that the tensile strength of the NSM-FRP bars was fully exploited whereas the EB-CFRP strips utilized only 29-36 % of their ultimate tensile strain due to debonding. A finite element (FE) model was formulated to anticipate the behavior of the strengthened slabs. A strong correlation between the numerical predictions and the experimental outcomes was observed. The experimental-to-numerical ratios of the ultimate load ranged between 1.0 and 1.08 for the NSM-strengthened slabs and between 0.98 and 1.38 for the EB-strengthened slabs. This validated the FE models' ability to capture the nonlinear performance of the strengthened slabs.The authors would like to acknowledge the financial support provided by the Natural Sciences and Engineering Research Council of Canada (NSERC) through their Discovery Grant Program - Award No. RGPIN-2017-04278 rewarded by the 2nd author and by Qatar University (Fund No. QUST-1-CENG-2020-17 ) rewarded by the 3rd author.Scopu
Are Two Interviews Better Than One? Memory across Repeated Cognitive Interviews.
No full textEyewitnesses to a filmed event were interviewed twice using a Cognitive Interview to examine the effects of variations in delay between the repeated interviews (immediately & 2 days; immediately & 7 days; 7 & 9 days) and the identity of the interviewers (same or different across the two repeated interviews). Hypermnesia (an increase in total amount of information recalled in the repeated interview) occurred without any decrease in the overall accuracy. Reminiscence (the recall of new information in the repeated interview) was also found in all conditions but was least apparent in the longest delay condition, and came with little cost to the overall accuracy of information gathered. The number of errors, increased across the interviews, but the relative accuracy of participants' responses was unaffected. However, when accuracy was calculated based on all unique details provided across both interviews and compared to the accuracy of recall in just the first interview it was found to be slightly lower. The identity of the interviewer (whether the same or different across interviews) had no effects on the number of correct details. There was an increase in recall of new details with little cost to the overall accuracy of information gathered. Importantly, these results suggest that witnesses are unlikely to report everything they remember during a single Cognitive Interview, however exhaustive, and a second opportunity to recall information about the events in question may provide investigators with additional information
A survey of attitudes towards patient substance abuse/addiction in the emergency center.
No full textIncludes abstract.Includes bibliograpical references.Hospitals across South Africa are inundated with patients suffering from conditions associated with substance abuse. It is inevitable that contact with health services be made through an emergency centre (EC) at some point. This study aims to assess the exposure and attitudes of emergency physicians to substance abuse and addiction in major South African academic ECs. A prospective survey based on the Substance Abuse Attitude Survey (SAAS) was conducted in a convenience sample of eighty five emergency physician registrars and junior consultants in Cape Town, Gauteng, Limpopo and KwaZulu Natal. Respondents were targeted during academic meetings and by post
On Using Gait in Forensic Biometrics
No full textGiven the continuing advances in gait biometrics, it appears prudent to investigate the translation of these techniques for forensic use. We address the question as to the confidence that might be given between any two such measurements. We use the locations of ankle, knee and hip to derive a measure of the match between walking subjects in image sequences. The Instantaneous Posture Match algorithm, using Harr templates, kinematics and anthropomorphic knowledge is used to determine their location. This is demonstrated using real CCTV recorded at Gatwick Airport, laboratory images from the multi-view CASIA-B dataset and an example of real scene of crime video. To access the measurement confidence we study the mean intra- and inter-match scores as a function of database size. These measures converge to constant and separate values, indicating that the match measure derived from individual comparisons is considerably smaller than the average match measure from a population
International Diabetes Federation guideline for management of postmeal glucose : a review of recommendations
No full textDiabetes is a significant and growing concern, with over 246 million people around the world living with the disease and another 308 million with impaired glucose tolerance. Depending on the resources of different nations, intervention has generally focused on optimizing overall glycaemic control as assessed by glycated haemoglobin (HbA1c) and fasting plasma glucose (FPG) values. Nevertheless, increasing evidence supports the importance of controlling all three members of the glucose triad, namely HbA1c, FPG and postmeal glucose (PMG) in order to improve outcome in diabetes. As part of its global mission to promote diabetes care and prevention and to find a cure, the International Diabetes Federation (IDF) recently developed a guideline that reviews evidence to date on PMG and the development of diabetic complications. Based on an extensive database search of the literature, and guided by a Steering and Development Committee including experts from around the world, the IDF Guideline for Management of Postmeal Glucose offers recommendations for appropriate clinical management of PMG. These recommendations are intended to help clinicians and organizations in developing strategies for effective management of PMG in individuals with Type 1 and Type 2 diabetes. The following review highlights the recommendations of the guideline, the supporting evidence provided and the major conclusions drawn. The full guideline is available for download at www.idf.org
Characterisation of Miscanthus genetic resources: a combined analysis of plastid and nuclear microsatellites, nrDNA sequences, flow cytometry and morphology.
No full textDoctoral ThesisMiscanthus is a highly important forage and horticultural genus of perennial grasses
(Poaceae) primarily native to South East Asia. Miscanthus is under intense global
investigation as a biomass source for renewable energy production and several breeding initiatives are underway to develop new genotypes optimized for improved biomass and tolerance to a range of environmental stress conditions. A collection of 128 accessions belonging to the genus Miscanthus was established in Oak Park, Teagasc, Carlow, in 2008 and was investigated for morphological and molecular variation. Morphological traits were measured at the end of the second growing season and were compared with herbarium specimens of Miscanthus. Vegetative and inflorescence traits were scored and analysed using
basic summary statistics, tests of normality and Principal Components Analysis (PCA). A
large degree of morphological variation was recorded in the collections. The PCA of
herbarium specimens was able to separate some species from others but there was also
considerable overlap among species in the ordination, especially M. sacchariflorus, M.
sinensis, M. condensatus and M. floridulus. These are known to be closely related and can
interbreed. The PCA of the specimens from the Oak Park collection was less informative
because of missing data due to lack of inflorescences (accessions did not flower). It was clear that morphology alone is often insufficient to distinguish taxa especially when inflorescence characters and ploidy information is lacking. The ploidy level of the accessions in the collection was evaluated through flow cytometry.
The ploidy included di-, tri- and tetraploids. All individuals labelled as M. ×giganteus showed a triploid status, together with the newly bred M. sacchariflorus×M. sinensis hybrids.
Most M. sinensis were diploids. Miscanthus sinensis Tea-62 was triploid and comparable to the value of the M. ×giganteus. A different situation was found for other non-diploid M. sinensis, in particular four M. sinensis ‘Goliath’ and the M. sinensis ‘Zebrinus’ Tea-33. In these the ratio measured by the flowcytometer was in between the values of the triploid M. giganteus and tetraploid M. sacchariflorus standards. The ‘Goliath-like’ hybrid is likely an
autotriploid with three M. sinensis haploid sets, whereas M. ×giganteus is an allotriploid that is supposed to have two genomes from M. sinensis and one from M. sacchariflorus, which has a lower amount of DNA per haploid genome. DNA sequences of the internal transcribed spacer of the nrDNA were obtained for 76 genotypes in the collection and compared for polymorphism. The SNPs were particularly VI useful for differentiating M. sinensis, M. sacchariflorus and M. ×giganteus accessions and in combination with ploidy and morphology offer high potential for taxon identification. To gather more markers for population level diversity and differentiation studies, new microsatellite markers for both plastid and nuclear genomes were developed. For the development of plastid markers the chloroplast genome information of Saccharum officinarum was used. The nuclear SSRs (nSSRs) were developed from the sequences of 192
clones obtained from microsatellite enriched library. New primer pairs for the amplification of nineteen nuclear loci and six chloroplast loci were developed. Both chloroplast (cpSSR) and nSSR primers were used to characterise DNA variation, to help establish gene pools and to better understand hybridization and introgression. Huge genotypic variation was found
within the genus, mostly in the species M. sinensis. The markers showed wide utility across a large number of Miscanthus species and also some closely related genera. The analysis of the cpSSRs showed a high number of different haplotypes but with a clear bias in allele composition between M. sinensis and the two species M. sacchariflorus and M. ×giganteus,
thus confirming M. sacchariflorus as the maternal lineage of the hybrid M. xgiganteus. The nSSRs were found to be highly polymorphic across the collection and transferable to closely related genera such as Saccharum. The new markers were also used in UPGMA clustering and Bayesian structuring analysis to group individuals according to their similarity. Three major clusters of individuals were defined using the Bayesian STRUCTURE analysis with nuclear markers (nSSRs) and two with plastid markers (cpSSRs).
In conclusion, the morphological, ploidy, sequence and microsatellite results highlighted the high level of diversity still unexplored in the genus and have clarified taxon identity of many
accessions in the collection. A large set of new markers have been developed for the plant
breeding and systematics community. The newly developed markers will be useful to further explore this diversity and to select useful traits for breeding of new and improved genotypes for biomass production.Teagasc Walsh Fellowship; National Development Plan Irelan
Probabilistic risk assessment modelling for passenger aircraft fire safety
No full textThis thesis describes the development
of a computer simulation model
for the
investigation
of airliner
fire
accident safety.
The
aim of the work
has been to create a computer-based analysis tool that generates
representative aircraft accident scenarios and then simulates their outcome
in terms of
passenger injuries
and
fatalities. The details
of the accident scenarios are
formulated
to closely match the type of events that are
known to have
occurred
in
aircraft
accidents over the last 40
years.
This information has been obtained
by
compiling a
database
and undertaking
detailed
analysis of approximately
200
airliner
fire
accidents. In
addition to utilising
historical data, the modelling work
has incorporated
many of the key findings
obtained
from
experimental research undertaken
by the
world's air safety community.
An
unusual
feature of the simulation process is that all critical aspects of the accident
scenario have been analysed and catered for in the formative
stages of the programme
development. This has
enabled complex effects, such as cabin crash
disruption,
impact trauma injuries, fire
spread, smoke
incapacitation
and passenger evacuation to
be
simulated
in
a
balanced and
integrated manner.
The
study
is intended to further the general appreciation and understanding of the
complex events that lead to fatalities in
aircraft
fire
accidents.
This is
achieved
by
analysing all contributory
factors that are
likely to arise
in
real
fire
accident scenarios
and undertaking quantitative risk assessment through the use of novel simulation
methods. Future development
of the research could potentially enable the undertaking
of a systematic exploration and appraisal of the effectiveness of
both
current and
future
aircraft
fire
safety policies
Gene gain and loss during evolution of obligate parasitism in the white rust pathogen of Arabidopsis thaliana
No full textBiotrophic eukaryotic plant pathogens require a living host for their growth and form an intimate haustorial interface with parasitized cells. Evolution to biotrophy occurred independently in fungal rusts and powdery mildews, and in oomycete white rusts and downy mildews. Biotroph evolution and molecular mechanisms of biotrophy are poorly understood. It has been proposed, but not shown, that obligate biotrophy results from (i) reduced selection for maintenance of biosynthetic pathways and (ii) gain of mechanisms to evade host recognition or suppress host defence. Here we use Illumina sequencing to define the genome, transcriptome, and gene models for the obligate biotroph oomycete and Arabidopsis parasite, Albugo laibachii. A. laibachii is a member of the Chromalveolata, which incorporates Heterokonts (containing the oomycetes), Apicomplexa (which includes human parasites like Plasmodium falciparum and Toxoplasma gondii), and four other taxa.
From comparisons with other oomycete plant pathogens and other chromalveolates, we reveal independent loss of
molybdenum-cofactor-requiring enzymes in downy mildews, white rusts, and the malaria parasite P. falciparum. Biotrophy also requires ‘‘effectors’’ to suppress host defence; we reveal RXLR and Crinkler effectors shared with other oomycetes, and also discover and verify a novel class of effectors, the ‘‘CHXCs’’, by showing effector delivery and effector functionality. Our findings suggest that evolution to progressively more intimate association between host and parasite results in reduced selection for retention of certain biosynthetic pathways, and particularly reduced selection for retention of molybdopterinrequiring
biosynthetic pathways. These mechanisms are not only relevant to plant pathogenic oomycetes but also to
human pathogens within the Chromalveolata
Resilient places? The healthcare gardens and the Maggie's Centres
No full textThis thesis takes as its focus the Maggie’s Cancer Centres exploring for the first time the impact of their designed gardens. This research is situated within the immediate context of Maggie’s ambitions as an organisation and looks closely at their design process. It is also set within the wider debates about the effects of green space on health and the historical context of the restorative garden. By exploring both historical and contemporary examples, it argues that a healthcare garden may be a space for transformation.
Using four different Maggie’s gardens as case studies, the research seeks to investigate the role of these outdoor spaces and their impact on users. Through ethnographic and sensory methods, each garden is considered and mapped. It looks at the design brief and the intentions of the designers’, but the core work is an exploration of the experiences of staff and visitors. The focus is on the everyday use of these gardens as well as the design historiography. The experiences of gardens within healthcare are examined in order to expose the ways in which gardens, people, health and care are entwined.
Through the qualitative research process this thesis develops a new hypothesis as to how healthcare gardens may operate – offering a new definition for them as “resilient places”. Careful analysis of the data reveals the specific networks and affordances presented by these gardens. The thesis argues, based on the evidence of users, that healthcare gardens can uniquely embrace certain “essences” where essence is defined as conveying a quality or attribute. These garden essences are identified as thresholds, sensory richness, the density of time and homeliness. The thesis also argues that a healthcare garden can provide specific and unique opportunities for care and this, in turn, can enhance the healing ethos of an organisation such as Maggie’s
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