Een analytische en algebraïsche beschouwing van de Wilson- en Racahpolynomen

De Wilson- en Racahpolynomen zijn hypergeometrische orthogonale polynomen die helemaal bovenaan staan in het Askey-schema. Deze polynomen zijn de meest algemene hypergeometrische orthogonale polynomen in één variabele en generaliseren de andere hypergeometrische orthogonale polynomen in het Askey-schema.In deze scriptie wordt ingegaan op twee specifieke eigenschappen van de Wilson- en Racahpolynomen: de drieterms recurrente betrekking en de orthogonaliteitsrelatie. Deze eigenschappen worden met analytische en algebraïsche methoden bestudeerd.Bij de analytische methode wordt eerst algemene theorie van hypergeometrische functies en orthogonale polynomen bestudeerd. Er worden identiteiten, transformaties en aaneengesloten relaties voor hypergeometrische functies afgeleid. Hiermee kan de drieterms recurrente betrekking van de Wilson- en Racahpolynomen worden afgeleid. Met behulp van de residuenstelling van Cauchy en de theorie van hypergeometrische functies kan de orthogonaliteitsrelatie van beide polynomen worden verkregen.Bij de algebraïsche methode wordt de Racah-Wilsonalgebra bestudeerd. De Racah-Wilsonalgebra voldoet aan een zogenaamde laddereigenschap waarmee een keten van eigenvectoren kan worden geconstrueerd. Hiermee is het mogelijk om een eindig dimensionale irreducibele representatie te krijgen. Door een inproduct te definiëren op de bases van eigenvectoren van de generatoren van Racah-Wilsonalgebra, kan met behulp van overlapcoëfficiënten een drieterms recurrente betrekking worden afgeleid. Door vervolgens enkele transformaties toe te passen, kan worden aangetoond dat deze drieterms recurrente betrekking overeenkomt met de drieterms recurrente betrekking van de Racahpolynomen. Ten slotte laten we met dit gekozen inproduct zien dat de Racahpolynomen orthogonale polynomen zijn.Applied Mathematic

Non-Medical Use of Prescription Drugs Among Undergraduate Students

This study examines the non- medical, or recreational use, of prescription drugs among undergraduate students. Research conducted at University of Maryland, Baltimore County attempts to answer several research questions regarding the non- medical use of prescription medications. First, significant differences in the classifications of prescription drugs that are used for non- medical reasons will be examined. Demographic differences among various race and ethnic groups will also be explored in addition to differences between the gender, age, declared major and academic class standing in the non- medical use of prescription drugs. Lastly, the sources that provide undergraduate college students with the prescription drugs for non- medical use will be examined along with the reasons for such recreational use. Data are collected through self- administered surveys taken in classes across an array of disciplines across campus. Surveys are administered to all students within the selected classes as a method of reducing non-respondent bias

VERVANGINGSANALYSE EN CONTINUITEITSANALYSE

VERVANGINGSANALYSE EN CONTINUITEITSANALYS

Non-Medical Use of Prescription Drugs Among Undergraduate Students

This study examines the non- medical, or recreational use, of prescription drugs among undergraduate students. Research conducted at University of Maryland, Baltimore County attempts to answer several research questions regarding the non- medical use of prescription medications. First, significant differences in the classifications of prescription drugs that are used for non- medical reasons will be examined. Demographic differences among various race and ethnic groups will also be explored in addition to differences between the gender, age, declared major and academic class standing in the non- medical use of prescription drugs. Lastly, the sources that provide undergraduate college students with the prescription drugs for non- medical use will be examined along with the reasons for such recreational use. Data are collected through self- administered surveys taken in classes across an array of disciplines across campus. Surveys are administered to all students within the selected classes as a method of reducing non-respondent bias

Mass transfer limitations in binderless ZSM-5 zeolite granules during adsorption of flavour compounds from aqueous streams

BACKGROUND: Recently, a new process concept has been proposed to selectively adsorb wort offflavours, i.e. aldehydes, from alcohol-free beers with hydrophobic zeolites. RESULTS: In this work, we investigated the uptake of a mixture of wort flavour compounds (2-methylpropanal, 2-methylbutanal, 3methylbutanal, furfural and methional), from a model solution onto binderless, hydrophobic ZSM-5 zeolite granules in order to quantify mass transfer parameters and identify bottlenecks. Subsequently, the homogenous solid diffusion model was employed to regress the effective diffusion coefficients for each molecule and experimental condition, which ranged between 10-15 and 10-13 m2/s, indicating strong intraparticle mass transfer limitation. Furthermore, it was found that the effective diffusion coefficient is inversely correlated to the molecules’ hydrophobicity, expressed as the logD value and its isotherm affinity constant. CONCLUSION: These results give valuable insight to design and improved adsorbent material and an off-flavour removal unit for industrial scale

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

Background Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications. Methods We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC). Findings In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683–0·717]). Interpretation In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required. Funding British Journal of Surgery Society