A COMPUTATIONALLY CHEAP TRICK TO DETERMINE SHADOW IN A VOXEL MODEL

Representation of scenes on the Earth surface by using voxels is gaining attention because of its suitability for integrating heterogeneous data sources in simulations and quantitative models. Computation of shadows in such models is needed, for example, to obtain crop suitability of agricultural fields in the presence of trees and buildings, or to analyze urban heat island causes and effects. We present an efficient algorithm to compute which of the voxels in a dataset receive direct sunlight, given the solar azimuth and elevation angles. The algorithm can work with multiple (sparse and dense) voxel storage strategies

Early childhood infections and body mass index in adolescence

BACKGROUND: The incidence of childhood overweight and obesity is rising. It is hypothesized that infections in early childhood are associated with being overweight. This study investigated the association between the number of symptomatic infections or antibiotic prescriptions in the first 3 years of life and body mass index (BMI) in adolescence. SUBJECTS: The current study is part of the Prevention and Incidence of Asthma and Mite Allergy population-based birth cohort study. Weight and height were measured by trained research staff at ages 12 and 16 years. The 3015 active participants at age 18 years were asked for informed consent for general practitioner (GP) data collection and 1519 gave written informed consent. Studied exposures include (1) GP-diagnosed infections, (2) antibiotic prescriptions, and (3) parent-reported infections in the first 3 years of life. Generalized estimating equation analysis was used to determine the association between each of these exposures and BMI z-score. RESULTS: Exposure data and BMI measurement in adolescence were available for 622 participants. The frequencies of GP-diagnosed infections and antibiotic prescriptions were not associated with BMI z-score in adolescence with estimates being 0.14 (95% CI -0.09-0.37) and 0.10 (95% CI -0.14-0.34) for the highest exposure categories, respectively. Having ≥6 parent-reported infections up to age 3 years was associated with a 0.23 (95% CI 0.01-0.44) higher BMI z-score compared to <2 parent-reported infections. CONCLUSIONS: For all infectious disease measures an increase in BMI z-score for the highest childhood exposure to infectious disease was observed, although only statistically significant for parent-reported infections. These results do not show an evident link with infection severity, but suggest a possible cumulative effect of repeated symptomatic infections on overweight development

Advies Onderzoek medische zorg aan ouderen. In het bijzonder ouderen met multiple en complexe problematiek

Recent heeft de Raad voor Gezondheidsonderzoek (RGO) het advies “Medisch Onderzoek voor Ouderen” uitgebracht. Het advies richt zich vooral op onderzoek naar ouderen met multiple en complexe aandoeningen, en geeft antwoord op de vraag van de minister van VWS hoe het onderzoek zou kunnen helpen de belangrijkste problemen in de geriatrische zorg op te vangen. De minister vroeg de Raad vooral aan te geven hoe het wetenschappelijk onderzoek een bijdrage zou kunnen leveren aan de kwaliteit van de medisch geriatrische zorg ongeacht door welke beroepsgroep of specialisme deze wordt geleverd. De opdracht die de Raad daarnaast van de minister ontving was te verduidelijken ‘... hoe het bestaande wetenschappelijk potentieel en inzicht beter kan worden benut en ingezet. Dus niet weer nieuw onderzoek naast al het bestaande’

Changes in viral load and HBsAg and HBeAg status with age in HBV chronic carriers in The Gambia

<p>Abstract</p> <p>Background</p> <p>Little is known about changes in hepatitis B viral load (HBV DNA) in relation to age in Africa. The aim of this study is to determine the natural course of HBV chronic infection, particularly in relation to sequential changes in serum HBV DNA levels and hepatitis B surface (HBsAg) antigen/hepatitis e antigen (HBeAg) status by age.</p> <p>Methods</p> <p>The study was conducted on 190 HBV chronic carriers, aged 1–19 years who were followed for 19 years. 160, 99 and 123 were traced at 5, 9 and 19 years later. All available samples were tested for HBsAg and HBeAg, whilst 170, 61, 63 and 81 were tested for HBV DNA at the baseline, and at 5, 9 and 19 years following recruitment.</p> <p>Results</p> <p>In general HBeAg which correlated with high levels of HBV DNA was lost at a much faster rate than HBsAg. 86% of the carriers who were recruited at the age of 1–4 yrs lost HBeAg by the age of 19 years compared to 30% who lost HBsAg. HBeAg negative carriers had serum HBV DNA levels of < 10⁵copies per mL, HBV DNA positivity declined from 100% in 1–4 yrs old carriers at recruitment to 62.5%,60% and 88% at 5, 9 and 19 years respectively following recruitment.</p> <p>Conclusion</p> <p>After 19 years of follow up, the majority of HBV surface antigen carriers had lost HBeAg positivity and had low levels of viral replication. However small proportions (10–20%) retained HBeAg and continue to have high levels of viral replication.</p

Long-term outcomes of slipped capital femoral epiphysis treated with in situ pinning

PURPOSE: Slipped capital femoral epiphysis (SCFE) is the commonest hip disorder in adolescents. In situ pinning is commonly performed, yet lately there has been an increase in procedures with open reduction and internal fixation. These procedures, however, are technically demanding with relatively high complication rates and unknown long-term outcomes. Nevertheless, reports on long-term results of in situ fixation are not equivocal. This study evaluates the possible higher risk of worse outcome after in situ pinning of SCFE. METHODS: All patients treated for SCFE with in situ fixation between 1980 and 2002 in four different hospitals were asked to participate. Patients were divided into three groups, based on severity of the slip. Patients were invited to the outpatient clinic for physical examination and X-rays, and to fill out the questionnaires HOOS, EQ5D, and SF36. ANOVA and chi-squared tests were used to analyze differences between groups. RESULTS: Sixty-one patients with 78 slips filled out the questionnaires. Patients with severe slips had worse scores on HOOS, EQ5D, and SF36. 75 % of patients with severe slips had severe osteoarthritis, compared to 2 % of mild and 11 % of moderate slips. CONCLUSION: Hips with mild and moderate SCFE generally had good functional and radiological outcome at a mean follow-up of 18 years, and for these hips there seems to be no indication for open procedures. However, severe slips have a significantly worse outcome, and open reduction and internal fixation could therefore be considered

Encouraging survival rates in patients with acute myocardial infarction treated with an intra-aortic balloon pump

Objective To evaluate a 30-day and long-term outcome of patients with acute myocardial infarction (AMI) treated with intra-aortic balloon pump (IABP) counterpulsation and to identify predictors of a 30-day and long-term all-cause mortality. Methods Retrospective cohort study of 437 consecutive AMI patients treated with IABP between January 1990 and June 2004. A Cox proportional hazards model was used to identify predictors of a 30-day and long-term all-cause mortality. Results Mean age of the study population was 61±11 years, 80% of the patients were male, and 68% had cardiogenic shock. Survival until IABP removal after successful haemodynamic stabilisation was 78% (n=341). Cumulative 30-day survival was 68%. Median follow-up was 2.9 years (range, 6 months to 15 years). In patients who survived until IABP removal, cumulative 1-, 5-, and 10-year survival was 75%

Intradialytic protein ingestion and exercise do not compromise uremic toxin removal throughout hemodialysis

Objective Dietary protein and physical activity interventions are increasingly implemented during hemodialysis to support muscle maintenance in patients with end-stage renal disease (ESRD). Although muscle maintenance is important, adequate removal of uremic toxins throughout hemodialysis is the primary concern for patients. It remains to be established whether intradialytic protein ingestion and/or exercise modulate uremic toxin removal during hemodialysis. Methods We recruited 10 patients with ESRD (age: 65 ± 16 y, BMI: 24.2 ± 4.8 kg/m2) on chronic hemodialysis treatment to participate in this randomized cross-over trial. During hemodialysis, patients were assigned to ingest 40 g protein or a nonprotein placebo both at rest (protein [PRO] and placebo [PLA], respectively) and following 30 min of exercise (PRO + exercise [EX] and PLA + EX, respectively). Blood and spent dialysate samples were collected throughout hemodialysis to assess reduction ratios and removal of urea, creatinine, phosphate, cystatin C, and indoxyl sulfate. Results The reduction ratios of urea and indoxyl sulfate were higher during PLA (76 ± 6% and 46 ± 9%, respectively) and PLA + EX interventions (77 ± 5% and 45 ± 10%, respectively) when compared to PRO (72 ± 4% and 40 ± 8%, respectively) and PRO + EX interventions (73 ± 4% and 43 ± 7%, respectively; protein effect: P = .001 and P = .023, respectively; exercise effect: P = .25 and P = .52, respectively). Nonetheless, protein ingestion resulted in greater urea removal (P = .046) during hemodialysis. Reduction ratios and removal of creatinine, phosphate, and cystatin C during hemodialysis did not differ following intradialytic protein ingestion or exercise (protein effect: P > .05; exercise effect: P>.05). Urea, creatinine, and phosphate removal were greater throughout the period with intradialytic exercise during PLA + EX and PRO + EX interventions when compared to the same period during PLA and PRO interventions (exercise effect: P = .034, P = .039, and P = .022, respectively). Conclusion The removal of uremic toxins is not compromised by protein feeding and/or exercise implementation during hemodialysis in patients with ESRD