Introduction to biometrics - Iris Recognition

In this report an iris detection system will be designed, programmed and tested. It starts off by discussing the current state of biometric systems and how they are graded. It then goes on to introduce the various steps which are taken in iris detection and which variations are possible within these steps. Out of these variations a combined method is designed, consisting of preprocessing, feature extraction and matching of the iris. In preprocessing both the iris and pupil center are detected and used to normalise the iris. The iris is then normalised using a Doubly Pair Method. The feature extraction is then performed using a Gabor filter. In matching the iris a Hamming distance is used. In this paper three variations of this system will be tested, varying the detection method and the normalising method. A two point and a three point method of detecting the iris will be tested, and it will be tested whether or not the results improve when the outer 50% of the iris is excluded. Both for training as well as testing these systems the CASIA iris database 1.0 was used, consisting of 756 images of 108 eyes. In training, the first 70 images of ten eyes were used. The remaining images were used in the final test. The best results were achieved by combining the two-point method and excluding the outer 50% of the iris. On the personal computer used, the system takes 3 hours to analyse the CASIA iris database. It resulted in an Equal Error Rate of 7.63% and an failure to enroll of 6.1%. Finally, recommendations will be made to further improvement of the system

Identifying literacy and numeracy skill mismatch in OECD countries using the job analysis method

Skill mismatches have strong negative effects on productivity, job satisfaction, and other outcomes. To reduce skill mismatches, governments need to rely on accurate data on the prevalence of these mismatches. The Programme of the International Assessment of Adult Competences (PIAAC) is currently the most important data source providing excellent and unparalleled information for many countries on two key information-processing skills (i.e., literacy and numeracy skills). However, although these data contain rich information about possessed skills, countries lack directly comparable information on the required skills in those domains. Hence, it has been difficult to use the PIAAC data to identify skill mismatches, other than through proxies of required skills (e.g., the average skill level in occupations) or workers’ self-assessments of skill mismatch. In this paper, we use the Job Analysis Method (JAM) to determine the required skill levels of literacy and numeracy for all 4-digit ISCO08 unit groups of occupations in the same metric and scale as was used in PIAAC. JAM involves the use of occupational experts to rate the skill requirements in the different occupations. JAM has never been used before to identify required skill levels for literacy and numeracy as measured in PIAAC, and the paper thus presents the first results on the prevalence of skill shortages and skill surpluses in these key information-processing skills across different OECD countries and across different occupations and sectors that is based on a more direct estimate of the required skills. We provide estimates for the proportions of well-matched, overskilled and underskilled workers per country, and compare these with estimates based on alternative methods for estimating skill mismatch. We also compare JAM with these other methods in explaining wage differentials, as well as job satisfaction. We conclude that there are large differences in the estimates of the prevalence of skill mismatches depending on the method used. We show several advantages using JAM and discuss some of the limitations as well

Identifying literacy and numeracy skill mismatch in OECD countries using the job analysis method

Skill mismatches have strong negative effects on productivity, job satisfaction, and other outcomes. To reduce skill mismatches, governments need to rely on accurate data on the prevalence of these mismatches. The Programme of the International Assessment of Adult Competences (PIAAC) is currently the most important data source providing excellent and unparalleled information for many countries on two key information-processing skills (i.e., literacy and numeracy skills). However, although these data contain rich information about possessed skills, countries lack directly comparable information on the required skills in those domains. Hence, it has been difficult to use the PIAAC data to identify skill mismatches, other than through proxies of required skills (e.g., the average skill level in occupations) or workers’ self-assessments of skill mismatch. In this paper, we use the Job Analysis Method (JAM) to determine the required skill levels of literacy and numeracy for all 4-digit ISCO08 unit groups of occupations in the same metric and scale as was used in PIAAC. JAM involves the use of occupational experts to rate the skill requirements in the different occupations. JAM has never been used before to identify required skill levels for literacy and numeracy as measured in PIAAC, and the paper thus presents the first results on the prevalence of skill shortages and skill surpluses in these key information-processing skills across different OECD countries and across different occupations and sectors that is based on a more direct estimate of the required skills. We provide estimates for the proportions of well-matched, overskilled and underskilled workers per country, and compare these with estimates based on alternative methods for estimating skill mismatch. We also compare JAM with these other methods in explaining wage differentials, as well as job satisfaction. We conclude that there are large differences in the estimates of the prevalence of skill mismatches depending on the method used. We show several advantages using JAM and discuss some of the limitations as well

Optimizing the Timing of Highest Hydrocortisone Dose in Children and Adolescents With 21-Hydroxylase Deficiency

CONTEXT: Hydrocortisone treatment of young patients with 21-hydroxylase deficiency (21OHD) is given thrice daily, but there is debate about the optimal timing of the highest hydrocortisone dose, either mimicking the physiological diurnal rhythm (morning), or optimally suppressing androgen activity (evening). OBJECTIVE: We aimed to compare 2 standard hydrocortisone timing strategies, either highest dosage in the morning or evening, with respect to hormonal status throughout the day, nocturnal blood pressure (BP), and sleep and activity scores. METHODS: This 6-week crossover study included 39 patients (aged 4-19 years) with 21OHD. Patients were treated for 3 weeks with the highest hydrocortisone dose in the morning, followed by 3 weeks with the highest dose in the evening (n = 21), or vice versa (n = 18). Androstenedione (A4) and 17-hydroxyprogesterone (17OHP) levels were quantified in saliva collected at 5 am; 7 am; 3 pm; and 11 pm during the last 2 days of each treatment period. The main outcome measure was comparison of saliva 17OHP and A4 levels between the 2 treatment strategies. RESULTS: Administration of the highest dose in the evening resulted in significantly lower 17OHP levels at 5 am, whereas the highest dose in the morning resulted in significantly lower 17OHP and A4 levels in the afternoon. The 2 treatment dose regimens were comparable with respect to averaged daily hormone levels, nocturnal BP, and activity and sleep scores. CONCLUSION: No clear benefit for either treatment schedule was established. Given the variation in individual responses, we recommend individually optimizing dose distribution and monitoring disease control at multiple time points

Expert-independent classification of mature B-cell neoplasms using standardized flow cytometry: a multicentric study

Reproducible expert-independent flow-cytometric criteria for the differential diagnoses between mature B-cell neoplasms are lacking. We developed an algorithm-driven classification for these lymphomas by flow cytometry and compared it to the WHO gold standard diagnosis. Overall, 662 samples from 662 patients representing 9 disease categories were analyzed at 9 laboratories using the previously published EuroFlow 5-tube-8-color B-cell chronic lymphoproliferative disease antibody panel. Expression levels of all 26 markers from the panel were plotted by B-cell entity to construct a univariate, fully standardized diagnostic reference library. For multivariate data analysis, we subsequently used canonical correlation analysis of 176 training cases to project the multidimensional space of all 26 immunophenotypic parameters into 36 2-dimensional plots for each possible pairwise differential diagnosis. Diagnostic boundaries were fitted according to the distribution of the immunophenotypes of a given differential diagnosis. A diagnostic algorithm based on these projections was developed and subsequently validated using 486 independent cases. Negative predictive values exceeding 92.1% were observed for all disease categories except for follicular lymphoma. Particularly high positive predictive values were returned in chronic lymphocytic leukemia (99.1%), hairy cell leukemia (97.2%), follicular lymphoma (97.2%), and mantle cell lymphoma (95.4%). Burkitt and CD101 diffuse large B-cell lymphomas were difficult to distinguish by the algorithm. A similar ambiguity was observed between marginal zone, lymphoplasmacytic, and CD102 diffuse large B-cell lymphomas. The specificity of the approach exceeded 98% for all entities. The univariate immunophenotypic library and the multivariate expert-independent diagnostic algorithm might contribute to increased reproducibility of future diagnostics in mature B-cell neoplasms

Relationship between molecular pathogen detection and clinical disease in febrile children across Europe: a multicentre, prospective observational study

BackgroundThe PERFORM study aimed to understand causes of febrile childhood illness by comparing molecular pathogen detection with current clinical practice.MethodsFebrile children and controls were recruited on presentation to hospital in 9 European countries 2016-2020. Each child was assigned a standardized diagnostic category based on retrospective review of local clinical and microbiological data. Subsequently, centralised molecular tests (CMTs) for 19 respiratory and 27 blood pathogens were performed.FindingsOf 4611 febrile children, 643 (14%) were classified as definite bacterial infection (DB), 491 (11%) as definite viral infection (DV), and 3477 (75%) had uncertain aetiology. 1061 controls without infection were recruited. CMTs detected blood bacteria more frequently in DB than DV cases for N. meningitidis (OR: 3.37, 95% CI: 1.92-5.99), S. pneumoniae (OR: 3.89, 95% CI: 2.07-7.59), Group A streptococcus (OR 2.73, 95% CI 1.13-6.09) and E. coli (OR 2.7, 95% CI 1.02-6.71). Respiratory viruses were more common in febrile children than controls, but only influenza A (OR 0.24, 95% CI 0.11-0.46), influenza B (OR 0.12, 95% CI 0.02-0.37) and RSV (OR 0.16, 95% CI: 0.06-0.36) were less common in DB than DV cases. Of 16 blood viruses, enterovirus (OR 0.43, 95% CI 0.23-0.72) and EBV (OR 0.71, 95% CI 0.56-0.90) were detected less often in DB than DV cases. Combined local diagnostics and CMTs respectively detected blood viruses and respiratory viruses in 360 (56%) and 161 (25%) of DB cases, and virus detection ruled-out bacterial infection poorly, with predictive values of 0.64 and 0.68 respectively.InterpretationMost febrile children cannot be conclusively defined as having bacterial or viral infection when molecular tests supplement conventional approaches. Viruses are detected in most patients with bacterial infections, and the clinical value of individual pathogen detection in determining treatment is low. New approaches are needed to help determine which febrile children require antibiotics.FundingEU Horizon 2020 grant 668303

Genomic investigations of unexplained acute hepatitis in children

Since its first identification in Scotland, over 1,000 cases of unexplained paediatric hepatitis in children have been reported worldwide, including 278 cases in the UK1. Here we report an investigation of 38 cases, 66 age-matched immunocompetent controls and 21 immunocompromised comparator participants, using a combination of genomic, transcriptomic, proteomic and immunohistochemical methods. We detected high levels of adeno-associated virus 2 (AAV2) DNA in the liver, blood, plasma or stool from 27 of 28 cases. We found low levels of adenovirus (HAdV) and human herpesvirus 6B (HHV-6B) in 23 of 31 and 16 of 23, respectively, of the cases tested. By contrast, AAV2 was infrequently detected and at low titre in the blood or the liver from control children with HAdV, even when profoundly immunosuppressed. AAV2, HAdV and HHV-6 phylogeny excluded the emergence of novel strains in cases. Histological analyses of explanted livers showed enrichment for T cells and B lineage cells. Proteomic comparison of liver tissue from cases and healthy controls identified increased expression of HLA class 2, immunoglobulin variable regions and complement proteins. HAdV and AAV2 proteins were not detected in the livers. Instead, we identified AAV2 DNA complexes reflecting both HAdV-mediated and HHV-6B-mediated replication. We hypothesize that high levels of abnormal AAV2 replication products aided by HAdV and, in severe cases, HHV-6B may have triggered immune-mediated hepatic disease in genetically and immunologically predisposed children

Interventional nuclear imaging for radioembolistation guidance

The aim of this thesis is to investigate the development and application of a device which can acquire both fluoroscopic and nuclear images in the intervention room for guidance of liver radioembolisation procedures. The first part describes the development of the hardware required for such a hybrid imaging device. A hybrid imaging modality, consisting of an x-ray c-arm combined with a four gamma cameras placed adjacent to the x-ray tube, was previously developed and found feasible. We showed that nuclear image quality of this device can be improved by using parallel hole collimators, instead of the previously used pinhole collimators. However, the required intermediate reconstruction step and the added weight to the already heavy x-ray tube were not ideal. Therefore, a dual layer detector, consisting of an x-ray flat panel placed in front of a gamma camera with cone beam collimator focussed at the x-ray focal spot, was designed. This design relies on the x-ray detector absorbing the majority of the x-rays, while being more transparent to the higher energy gamma photons. No intermediate reconstruction step is needed and fluoroscopic and nuclear images are intrinsically registered to each other. The proposed dual layer detector was found to be capable of acquiring real-time intrinsically registered hybrid images. This could aid interventional procedures involving radionuclides, such as radioembolisation. The efficiency of radioembolisation procedures could be greatly enhanced if results of the 99mTc-MAA pre-treatment procedure would already be available in the intervention room, enabling single-session procedures thanks to direct intrahepatic dose feedback, assessment of extrahepatic depositions and lung shunt estimation. The second part of this thesis concerned the improvement of radioembolisation procedures by interventional hybrid imaging and other nuclear imaging techniques. Depending on the lung shunt fraction (LSF), treatment may be altered or abandoned. We showed that LSF can be estimated with a constant minor error with our hybrid imaging device within a few seconds in an interventional setting. To evaluate the intrahepatic distribution and the presence of any extrahepatic depositions, a SPECT scan is needed. A clinical SPECT scan, however, takes approximately 30 minutes, which is too long for interventional purposes. We have investigated whether a fast SPECT protocol is feasible and if non-uniform projection-time acquisition protocols improve accuracy. In was concluded that both uniform and non-uniform projection-time acquisition liver SPECT protocols yield accurate dosimetric metrics for radioembolisation treatment planning in the interventional suite within 10 minutes, without compromising image quality. Consequently, fast interventional SPECT of the liver in the intervention room is feasible. Radioembolisation is increasingly used as a bridge to resection (i.e. radiation lobectomy). It combines ipsilateral tumor control with the induction of contralateral hypertrophy to facilitate lobar resection. The potential complementary value of hepatobiliary scintigraphy (HBS) before and after radioembolisation in the assessment of the future remnant liver was investigated