Drying of liquid food droplets : enzyme inactivation and multicomponent diffusion

In this thesis the drying of liquid food droplets is studied from three different points of view: drying kinetics, enzyme inactivation and multicomponent diffusion. Mathematical models are developed and validated experimentally.Drying experiments are performed with suspended droplets and with free falling droplets under spray-drying conditions. The experiments with the free falling droplets are performed in a specially designed drying tower using a resonance nozzle. The resonance nozzle is capable of producing equally sized droplets.Thermal enzyme inactivation kinetics are determined at different water concentrations in separate experiments. The inactivation kinetics can be described by a first order Arrhenius-type model.A mathematical model based on the binary diffusion equation and the inactivation kinetics is developed that describes the drying kinetics of the droplets as well as the enzyme inactivation. The significance of the spray-air mixing pattern on enzyme inactivation is examined using the developed model.Slab drying experiments are performed with a ternary food model system. All experiments show that segregation of the dissolved solids can occur. This segregation cannot be described by a binary diffusion equation. Therefore the Maxwell-Stefan multicomponent diffusion equations are applied. Model simulations are used to examine the extent of segregation during spray-drying

Clinical infections and nonsurgical treatment of parapharyngeal space infections complicating throat infection

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Proportions of the aesthetic African-Caribbean face : idealized ratios, comparison with the golden proportion and perceptions of attractiveness

Abstract Background In the absence of clear guidelines for facial aesthetic surgery, most surgeons rely on expert intuitive judgement when planning aesthetic and reconstructive surgery. One of the most famous theories regarding “ideal” facial proportions is that of the golden proportion. However, there are conflicting opinions as to whether it can be used to assess facial attractiveness. The aim of this investigation was to assess facial ratios of professional black models and to compare the ratios with the golden proportion. Methods Forty photographs of male and female professional black models were collected. Observers were asked to assign a score from 1 to 10 (1 = not very attractive, 10 = very attractive). A total of 287 responses were analysed for grading behaviour according to various demographic factors by two groups of observers. The best graded photographs were compared with the least well-graded photographs to identify any differences in their facial ratios. The models’ facial ratios were calculated and compared with the golden proportion. Results Differences in grading behaviour were observed amongst the two assessment groups. Only one out of the 12 facial ratios was not significantly different from the golden proportion. Conclusions Only one facial ratio was observed to be similar to the golden proportion in professional model facial photographs. No correlation was found between facial ratios in professional black models with the golden proportion. It is proposed that an individualistic treatment for each ratio is a rather better method to guide future practice

Nationwide Outcome after Pancreatoduodenectomy in Patients at very High Risk (ISGPS-D) for Postoperative Pancreatic Fistula

OBJECTIVE: To assess nationwide surgical outcome after pancreatoduodenectomy (PD) in patients at very high risk for postoperative pancreatic fistula (POPF), categorized as ISGPS-D.SUMMARY BACKGROUND DATA: Morbidity and mortality after ISGPS-D PD is perceived so high that a recent randomized trial advocated prophylactic total pancreatectomy (TP) as alternative aiming to lower this risk. However, current outcomes of ISGPS-D PD remain unknown as large nationwide series are lacking.METHODS: Nationwide retrospective analysis including consecutive patients undergoing ISGPS-D PD (i.e., soft texture and pancreatic duct ≤3 mm), using the mandatory Dutch Pancreatic Cancer Audit (2014-2021). Primary outcome was in-hospital mortality and secondary outcomes included major morbidity (i.e., Clavien-Dindo grade ≥IIIa) and POPF (ISGPS grade B/C). The use of prophylactic TP to avoid POPF during the study period was assessed.RESULTS: Overall, 1402 patients were included. In-hospital mortality was 4.1% (n=57), which decreased to 3.7% (n=20/536) in the last 2 years. Major morbidity occurred in 642 patients (45.9%) and POPF in 410 (30.0%), which corresponded with failure to rescue in 8.9% (n=57/642). Patients with POPF had increased rates of major morbidity (88.0% vs. 28.3%; P&lt;0.001) and mortality (6.3% vs. 3.5%; P=0.016), compared to patients without POPF. Among 190 patients undergoing TP, prophylactic TP to prevent POPF was performed in 4 (2.1%).CONCLUSION: This nationwide series found a 4.1% in-hospital mortality after ISGPS-D PD with 45.9% major morbidity, leaving little room for improvement through prophylactic TP. Nevertheless, given the outcomes in 30% of patients who develop POPF, future randomized trials should aim to prevent and mitigate POPF in this high-risk category.</p

Nationwide Outcome after Pancreatoduodenectomy in Patients at very High Risk (ISGPS-D) for Postoperative Pancreatic Fistula

OBJECTIVE: To assess nationwide surgical outcome after pancreatoduodenectomy (PD) in patients at very high risk for postoperative pancreatic fistula (POPF), categorized as ISGPS-D.SUMMARY BACKGROUND DATA: Morbidity and mortality after ISGPS-D PD is perceived so high that a recent randomized trial advocated prophylactic total pancreatectomy (TP) as alternative aiming to lower this risk. However, current outcomes of ISGPS-D PD remain unknown as large nationwide series are lacking.METHODS: Nationwide retrospective analysis including consecutive patients undergoing ISGPS-D PD (i.e., soft texture and pancreatic duct ≤3 mm), using the mandatory Dutch Pancreatic Cancer Audit (2014-2021). Primary outcome was in-hospital mortality and secondary outcomes included major morbidity (i.e., Clavien-Dindo grade ≥IIIa) and POPF (ISGPS grade B/C). The use of prophylactic TP to avoid POPF during the study period was assessed.RESULTS: Overall, 1402 patients were included. In-hospital mortality was 4.1% (n=57), which decreased to 3.7% (n=20/536) in the last 2 years. Major morbidity occurred in 642 patients (45.9%) and POPF in 410 (30.0%), which corresponded with failure to rescue in 8.9% (n=57/642). Patients with POPF had increased rates of major morbidity (88.0% vs. 28.3%; P&lt;0.001) and mortality (6.3% vs. 3.5%; P=0.016), compared to patients without POPF. Among 190 patients undergoing TP, prophylactic TP to prevent POPF was performed in 4 (2.1%).CONCLUSION: This nationwide series found a 4.1% in-hospital mortality after ISGPS-D PD with 45.9% major morbidity, leaving little room for improvement through prophylactic TP. Nevertheless, given the outcomes in 30% of patients who develop POPF, future randomized trials should aim to prevent and mitigate POPF in this high-risk category.</p

Impact of Complications After Pancreatoduodenectomy on Mortality, Organ Failure, Hospital Stay, and Readmission Analysis of a Nationwide Audit:Analysis of a Nationwide Audit

OBJECTIVE: To quantify the impact of individual complications on mortality, organ failure, hospital stay, and readmission after pancreatoduodenectomy. SUMMARY OF BACKGROUND DATA: An initial complication may provoke a sequence of adverse events potentially leading to mortality after pancreatoduodenectomy. This study was conducted to aid prioritization of quality improvement initiatives. METHODS: Data from consecutive patients undergoing pancreatoduodenectomy (2014-2017) were extracted from the Dutch Pancreatic Cancer Audit. Population attributable fractions (PAF) were calculated for the association of each complication (ie, postoperative pancreatic fistula, postpancreatectomy hemorrhage, bile leakage, delayed gastric emptying, wound infection, and pneumonia) with each unfavorable outcome [ie, in-hospital mortality, organ failure, prolonged hospital stay (>75th percentile), and unplanned readmission), whereas adjusting for confounders and other complications. The PAF represents the proportion of an outcome that could be prevented if a complication would be eliminated completely. RESULTS: Overall, 2620 patients were analyzed. In-hospital mortality occurred in 95 patients (3.6%), organ failure in 198 patients (7.6%), and readmission in 427 patients (16.2%). Postoperative pancreatic fistula and postpancreatectomy hemorrhage had the greatest independent impact on mortality [PAF 25.7% (95% CI 13.4-37.9) and 32.8% (21.9-43.8), respectively] and organ failure [PAF 21.8% (95% CI 12.9-30.6) and 22.1% (15.0-29.1), respectively]. Delayed gastric emptying had the greatest independent impact on prolonged hospital stay [PAF 27.6% (95% CI 23.5-31.8)]. The impact of individual complications on unplanned readmission was smaller than 11%. CONCLUSION: Interventions focusing on postoperative pancreatic fistula and postpancreatectomy hemorrhage may have the greatest impact on in-hospital mortality and organ failure. To prevent prolonged hospital stay, initiatives should in addition focus on delayed gastric emptying

Quantifying culture gaps between physicians and managers in Dutch hospitals: a survey

Background: The demands in hospitals for safety and quality, combined with limitations in financing health care require effective cooperation between physicians and managers. The complex relationship between both groups has been described in literature. We aim to add a perspective to literature, by developing a questionnaire which provides an opportunity to quantitatively report and elaborate on the size and content of differences between physicians and managers. Insight gained from use of the questionnaire might enable us to reflect on these differences and could provide practical tools to improve cooperation between physicians and managers, with an aim to enhance hospital performance.\ud \ud Methods: The CG-Questionnaire was developed by adjusting, pre-testing, and shortening Kralewski's questionnaire, and appeared suitable to measure culture gaps. It was shortened by exploratory factor analysis, using principal-axis factoring extraction with Varimax rotation. The CG-Questionnaire was sent to all physicians and managers within 37 Dutch general hospitals. ANOVA and paired sample T-tests were used to determine significant differences between perceptions of daily work practices based in both professional cultures; culture gaps. The size and content of culture gaps were determined with descriptive statistics.\ud \ud Results: The total response (27%) consisted of 929 physicians and 310 managers. The Cronbachs alpha's were 0.70 - 0.79. Statistical analyses showed many differences; culture gaps were found in the present situation; they were even larger in the preferred situation. Differences between both groups can be classified into three categories: (1) culture gaps in the present situation and not in the preferred, (2) culture gaps in the preferred situation and not in the present, and (3) culture gaps in both situations.\ud \ud Conclusions: With data from the CG-Questionnaire it is now possible to measure the size and content of culture gaps between physicians and managers in hospitals. Results gained with the CG-Questionnaire enables hospitals to reflect on these differences. Combining the results, we distinguished three categories of increasing complexity. We linked these three categories to three methods from intergroup literature (enhanced information, contact and ultimately meta cognition) which could help to improve the cooperation between physicians and managers

The influence of a maternal vegan diet on carnitine and vitamin B2 concentrations in human milk

BackgroundThe maternal diet greatly influences the nutritional composition of human milk. With the rise of vegan diets by lactating mothers, there are concerns about the nutritional adequacy of their milk. Two important nutrients, vitamin B2 and carnitine, are mostly ingested via animal products.ObjectiveWe investigated the influence of a vegan diet on the vitamin B2 and carnitine concentrations in milk and serum of lactating women.MethodsIn this case–control study, 25 lactating mothers following an exclusive vegan diet were comparted to 25 healthy lactating mothers with an omnivorous diet without use of supplements. High-performance liquid chromatography and liquid chromatography–tandem mass spectrometry were used to measure vitamin B2 and carnitine concentrations, respectively. A linear regression model was used to determine differences in human milk and serum concentrations between study groups.ResultsVitamin B2 concentrations in human milk and serum did not differ between study groups. While the human milk free carnitine (C0) and acetyl carnitine (C2) concentrations did not differ between study groups, serum carnitine concentrations were lower in participants following a vegan diet than in omnivorous women (p &lt; 0.0001).ConclusionA maternal vegan diet did not affect human milk concentration of vitamin B2 and carnitine. Breastfed infants of mothers following an exclusive vegan diet therefore are likely not at increased risk of developing a vitamin B2 or carnitine deficiency

Comparison of thallium-201 SPECT redistribution patterns and rubidium-82 PET rest-stress myocardial blood flow imaging

To compare regional thallium-201 SPECT redistribution patterns with rubidium-82 PET, we studied 81 patients with both imaging modalities. Sixty patients had significant coronary artery disease. All patients underwent PET imaging after dipyridamole infusion, while SPECT imaging was performed after exercise stress (38 patients) and dipyridamole (43 patients). Sixty-eight percent of patients with prior infarct had fixed defects on SPECT, compared to 39% with PET. Sixty-one percent of patients with prior infarct had PET perfusion defects which exhibited ‘reflow’ or normal rubidium-82 tracer uptake (p < 0.05 vs. SPECT). Similar results were seen in patients without prior infarct (26% fixed defects on SPECT vs. 12% for PET, p < 0.05). Regional analysis showed that 57% of fixed SPECT defects corresponded to PET defects with reflow or normal rubidium-82 uptake, while 78% of ‘fixed’ PET defects corresponded to fixed SPECT defects. PET reflow and normal rubidium-82 uptake in sites of fixed thallium-201 SPECT perfusion defects suggest that imaging modalities employing separate tracer injections at rest and after stress, such as rubidium-82 PET, may be more specific in the assessment of myocardial viability, especially in patients with prior myocardial infarction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42537/1/10554_2005_Article_BF01151577.pd