The development of the national accelerator centre proton microprobe as an analytical tool in geochemistry

Bibliography: pages 94-99.This thesis describes work performed to establish and demonstrate a quantitative trace element microanalysis technique for geological material using protons accelerated by the Van de Graaff Accelerator at the National Accelerator Centre (NAC) in Faure near Cape Town. The method relies on the analysis of Proton Induced X-ray Emission (PIXE) spectra, interpreted with the help of the GeoPIXE software package. The use of the Si(Li) energy dispersive detector provides simultaneous multi-element detection at the parts-per-million (ppm) level, and a scanning beam facility permits trace element distributions to be studied at these levels. The calibration of the detector efficiency and the thicknesses of selectable X-ray attenuating filters was performed using pure elemental samples. This involved the accurate determination of the target to detector distance, the thickness of the active volume of the Si(Li) detector crystal, the thicknesses of all the absorbing layers between the sample and the detector crystal, and the assessment of the effects of incomplete charge collection in the detector

Shared services:hoe effectief is de regieorganisatie?

Ondanks de in de managementliteratuur beloofde voordelen leidt het concentreren van ondersteunende processen in shared service centers (SSC’s) in de praktijk vaak tot problemen, vooral op het terrein van de coördinatie. Dit heeft grote gevolgen voor de effectiviteit van SSC’s. Een strategie die steeds vaker toegepast wordt om deze problemen op te lossen, is de vorming van een regieorganisatie die verantwoordelijk is voor het afstemmen van de vraag naar en het aanbod van ondersteunende diensten. Deze strategie blijft gericht op het realiseren van efficiencyvoordelen door ‘economies of scale’. Maar is de regieorganisatie wel effectief? In dit artikel analyseren we de regieorganisatie vanuit het systeemtheoretisch perspectief op organisatieontwerp en evalueren we de effectiviteit ervan in een recent, diepgaand onderzoek in een grote Nederlandse organisatie. We concluderen dat de regieorganisatie de problemen niet oplost. Integendeel: de problemen nemen toe en de kosten stijgen. Wij pleiten daarom voor de ontwikkeling van een andere, meer effectieve strategie, gericht op het realiseren van ‘economies of flow’ in de ondersteunende processen

Social media reviews to investigate restaurant dinning experiences

Restaurateurs often assume that customers' online reviews of their dining experiences are a reflection of their dining preferences. This study finds this assumption not to be true. Online written reviews do not explain diners’ preferred dining experiences. In this study post-experience reactions captured in reviews are shown to be contextually different to established dining preferences. Results show online reviews to be most important in facilitating customer dining expectations, but not influencing customers’ preferences in dining experiences. Evidence gathered during the secondary research shows that in general, social media has become the great marketing equaliser in commerce. In the dining industry, restaurants cannot solely rely on traditional media in the initial attraction and retention of dining customers. Continuous interaction between the business and customers is increasingly necessary for restaurateurs to remain competitive and in-touch with customers’ needs. This study concentrates its research area on the post-experience evaluation phase as found on review websites, like TripAdvisor. TripAdvisor has especially become a popular means to perpetuate word-of-mouth opinions of dining experiences among prospective customers. Research shows clear evidence of the importance of other's online opinions in the consumer decision-making process. The main variables of the study, namely customer experiences, restaurant dining and social media, are theoretically explored within the disciplines of service management and customer behaviour. These theories have laid a sound foundation for the subsequent research methods followed. The main purpose of the study was using social media reviews from TripAdvisor to investigate dining experiences in the restaurant industry. The outcomes desired were: firstly to advise the restaurant industry about superior customer practices, secondly emphasising the importance for industry of social media use in the dining experience, and thirdly rendering clarification on the experience perceptions of customers about factors that might lead to ‘delight’ and ‘frustration’. This research centralises the constructs of delight and frustration factors, which are typically extremely emotional dining experiences for the customer, that have the common element of surprise. Methodologically, the research required two phases: firstly, the qualitative analysis of online user-generated content by content analysis. The global sample consisted of seven international cities, which included the best, worst and average-rated TripAdvisor restaurant reviews. The content analysis produced the theoretical base for the dining perception variables used in the empirical survey. In the second phase of the study, the global surveys administered resulted in measuring the general public’s perceptions of the delight and frustration factors of dining experiences. Subsequently, the research process required various quantitative data analyses to reach substantial results with inferences. The results and interpreted findings achieved were twofold: Firstly, from the content analysis: customers regard service quality as relatively unimportant in relation to the holistic dining experience. Customers regarded food and beverage quality as crucial in the dining experience. Value for money increasingly becomes an issue as customers become more frustrated, more so than when the dining was generally experienced as pleasant. Secondly, from the empirical data: mood and aesthetics are essential, especially when diners chose between their favourite restaurants. Further results show managing the service basics for restaurants is essential; this included welcoming, professional, attentive and friendly service. Service consistency has also proven to be imperative in customers’ perceptions. Results further show that different nationalities could perceive food quality and service reliability differently. In addition, men and women could perceive food quality, mood and aesthetics, and value for money differently. This study recommends various findings to the restaurant industry: most importantly that the post-experience reviews are contextually different to customers’ dining preferences. The factor determining the reputation of a restaurant is food quality and not so much service quality. Value for money should be associated with a specific service or product feature for it to be of meaningful consequence to the restaurateur

The effect of sepsis and short-term exposure to nitrous oxide on the bone marrow and the metabolism of vitamin B 12 and folate

It is recognised that prolonged anaesthesia with nitrous oxide (N20) induces megaloblastic anaemia by oxidising vitamin B12 To determine whether sepsis aggravates the effect of H20 on haemopoiesis 5 patients with severe sepsis, who required surgery and were exposed to short-term (45 - 105 minutes) N20 anaesthesia, were studied. Hone had evidence of pre-operative vitamin B12 or folate deficiency. The effect of the combination of N20 anaesthesia and sepsis on DNA synthesis in bone marrow cells was assessed morphologically, and by the deoxyuridine suppression test. In 3 patients exposed to the longest duration (75 - 105 minutes) of N20, addition of folinic acid and vitamin B12 partially improved the utilisation of deoxyuridine in vitro. No patient had evidence of megaloblastic haemopoiesis as judged by bone marrow morphology. It is concluded that prolonged N20 anaesthesia in patients with severe sepsis may adversely affect DNA synthesis. Although this effect did not manifest as overt megaloblastic erythropoiesis, it may be prudent to avoid N20 in such patients

Multidimensionaal organiseren: is dat slim?

In deze bijdrage presenteren we een aantal voorbeelden die laten zien dat verdieping van de unitstructuur een levensvatbaar alternatief is voor de vervanging van de unitstructuur door de multidimensionale organisatie (MDO), zoals voorgesteld door Strikwerda en Galbraith. In de MDO wordt gestreefd naar ‘resource efficiency’ en schaalvoordelen, terwijl het verdiepen van de unitstructuur gericht is op het bereiken van ‘flow efficiency’ en flow voordelen

Latent classes of sexual risk and corresponding STI and HIV positivity among MSM attending centres for sexual health in the Netherlands

Objectives: Continuing high STI positivity among men who have sex with men (MSM) attending centres for sexual health (CSH) indicates that high-risk behaviour is ongoing. The objective of this study was to gain a better insight into risk behaviours among MSM attending CSH and to explore STI and HIV positivity by subgroups. Methods: We used national data routinely collected during CSH consultations for this study. From September to December 2017, questions on group sex, substance use and sex with HIV-positive partners were asked at each CSH consultation. We analysed latent classes of client-related factors and sexual risk behaviour among MSM attending CSH in this period. We examined STI positivity and prevalence ratios by latent classes. Results: A total of six classes were identified in order of increasing risk: â € overall low-risk behaviour' (n=2974; 22.0%), â € Western origin and multiple sex partners' (MSP) (n=4182; 30.9%), â € Non-Western origin and MSP' (n=2496; 18.5%), â € living with HIV' (n=827; 6.1%), â € group sex and HIV-positive partners' (n=1798; 13.3%) and â € group sex and chemsex' (n=1239; 9.2%). The any STI positivity ranged from 14.0% in the overall low-risk behaviour class to 35.5% in the group sex and chemsex class. HIV positivity did not differ significantly between classes. The Western origin and MSP class was largest and accounted for the majority of STI and HIV infections. Conclusions: Although STI positivity increased with increased risky behaviours, considerable STI positivity was found in all six latent classes. Comparable HIV positivity between classes indicates risk reduction strategies among subgroups engaged in risky behaviours. The differences in risk behaviour and STI positivity require preventive strategies tailored to each subgroup

Effect of Short-Term Fasting on Systemic Cytochrome P450-Mediated Drug Metabolism in Healthy Subjects: A Randomized, Controlled, Crossover Study Using a Cocktail Approach

Background and Objective: Short-term fasting can alter drug exposure but it is unknown whether this is an effect of altered oral bioavailability and/or systemic clearance. Therefore, the aim of our study was to assess the effect of short-term fasting on oral bioavailability and systemic clearance of different drugs. Methods: In a randomized, controlled, crossover trial, 12 healthy subjects received a single administration of a cytochrome P450 (CYP) probe cocktail, consisting of caffeine (CYP1A2), metoprolol (CYP2D6), midazo