Impact of the COVID-19 pandemic on patients with paediatric cancer in low-income, middle-income and high-income countries: a multicentre, international, observational cohort study

Objectives Paediatric cancer is a leading cause of death for children. Children in low-income and middle-income countries (LMICs) were four times more likely to die than children in high-income countries (HICs). This study aimed to test the hypothesis that the COVID-19 pandemic had affected the delivery of healthcare services worldwide, and exacerbated the disparity in paediatric cancer outcomes between LMICs and HICs. Design A multicentre, international, collaborative cohort study. Setting 91 hospitals and cancer centres in 39 countries providing cancer treatment to paediatric patients between March and December 2020. Participants Patients were included if they were under the age of 18 years, and newly diagnosed with or undergoing active cancer treatment for Acute lymphoblastic leukaemia, non-Hodgkin\"s lymphoma, Hodgkin lymphoma, Wilms\" tumour, sarcoma, retinoblastoma, gliomas, medulloblastomas or neuroblastomas, in keeping with the WHO Global Initiative for Childhood Cancer. Main outcome measure All-cause mortality at 30 days and 90 days. Results 1660 patients were recruited. 219 children had changes to their treatment due to the pandemic. Patients in LMICs were primarily affected (n=182/219, 83.1%). Relative to patients with paediatric cancer in HICs, patients with paediatric cancer in LMICs had 12.1 (95% CI 2.93 to 50.3) and 7.9 (95% CI 3.2 to 19.7) times the odds of death at 30 days and 90 days, respectively, after presentation during the COVID-19 pandemic (p<0.001). After adjusting for confounders, patients with paediatric cancer in LMICs had 15.6 (95% CI 3.7 to 65.8) times the odds of death at 30 days (p<0.001). Conclusions The COVID-19 pandemic has affected paediatric oncology service provision. It has disproportionately affected patients in LMICs, highlighting and compounding existing disparities in healthcare systems globally that need addressing urgently. However, many patients with paediatric cancer continued to receive their normal standard of care. This speaks to the adaptability and resilience of healthcare systems and healthcare workers globally

Dynamic stability analysis of pretwisted aerofoil cross-section blade packets under rotating conditions

This paper presents a finite element model for the static and dynamic stability of a rotating pretwisted aerofoil cross-section two-bladed packet subjected to uniform radial periodic force. The effects of various parameters such as shroud dimensions, pretwist angle, stagger angle, rotational speed and distance of shear center from the centroid on the stability of the blade packets are presented. The numerical results show that pretwist angle and the coupling effect are important in high-frequency modes depending on shear center distance from the centroid on dynamic stability regions. The increase in stagger angle makes the pretwisted two-bladed packet less stable. However, the increase in rotational speed makes the pretwisted two-bladed packet more stable. (c) 2007 Elsevier Ltd. All rights reserved

Dynamic stability analysis of rotating asymmetric cross-section blade packets

In this paper static and dynamic stability of rotating asymmetric cross-section two-bladed packets subjected to uniform radial periodic force are studied using the finite element method. The effects of various parameters such as shroud dimensions, stagger angle, rotational speed and distance of shear center from the centroid on the stability of the blade packets are presented. The numerical results indicate that the coupling effect is important in frequency modes depending on shear center distance from the centroid. The increase in stagger angle makes the two-bladed packet less stable. However, the increase in rotational speed makes the two-bladed packet more stable. (C) 2006 Elsevier Ltd. All rights reserved

A stochastic programming approach to multicriteria portfolio optimization

We study a stochastic programming approach to multicriteria multi-period portfolio optimization problem. We use a Single Index Model to estimate the returns of stocks from a market-representative index and a random walk model to generate scenarios on the possible values of the index return. We consider expected return, Conditional Value at Risk and liquidity as our criteria. With stocks from Istanbul Stock Exchange, we make computational studies for the two and three-criteria cases. We demonstrate the tradeoffs between criteria and show that treating these criteria simultaneously yields meaningful efficient solutions. We provide insights based on our experiments

Dynamic stability of multi-span frames subjected to periodic loading

In this study, in-plane dynamic stability analysis of multi-span frames, which are composed of columns and beams and subjected to periodic loading, is investigated by using the Finite Element Method. Periodic loading is considered to be applied to each column member as an axial load and no loading is applied on the beams. The effects of beam to column length ratio, beam to column cross-section ratio and beam to column moment of area ratio are investigated for in-plane frames. In addition, the effect of the number of span and static and dynamic load parameters on the free vibration, buckling and dynamic stability analysis is also investigated. The results are compared with the recent literature in terms of the fundamental natural frequency and critical buckling load. (C) 2011 Elsevier Ltd. All rights reserved

EFFECTS OF MULTIPLE CRITERIA ON PORTFOLIO OPTIMIZATION

We study the effects of considering different criteria simultaneously on portfolio optimization. Using a single-period optimization setting, we use various combinations of expected return, variance, liquidity and Conditional Value at Risk criteria. With stocks from Borsa Istanbul, we make computational studies to show the effects of these criteria on objective and decision spaces. We also consider cardinality and weight constraints and study their effects on the results. In general, we observe that considering alternative criteria results in enlarged regions in the effi-cient frontier that may be of interest to the decision maker. We discuss the results of our experiments and provide insights

Color correction of stained tissue section images by histogram transfer according to control images

© Science Printers and Publishers, Inc.OBJECTIVE: To present a color correction method by histogram transfer depending upon control tissue image (CTI) differences, and subsequently evaluate its performance. STUDY DESIGN: Images from colon and placenta sections stained by anti-CD34 were used as CTI and/or sample tissue images (STIs). In total, 36 slides were stained: 1 according to standard procedure and 35 with some variation in the durations or dilutions used for the staining process. For hematoxylin and eosin (20 slides) and Van Gieson (20 slides) stains, colonic mucosa and liver tissues were used. Digital images without normalization were taken by a CCD camera connected to a light microscope and stored on a computer. A software tool was developed in order to find the histogram difference between 2 CTIs and transfer the difference to the STI for achieving a corrected STI (corSTI). sSTI (1 image) and STI and corSTI (for each image) were semiquantitatively scored by 2 observers in blind fashion, and the STI and corSTI scores were compared with the sSTI score. Total optic density (TOD) and median optic density (MOD) and intensity were also calculated by the software. RESULTS: The STI semiquantitative score was equal to the sSTI in 23.5% of the image; this improved to 76.35% when the corSTI was compared to the sSTI. The concordance of TOD and intensity values of CD34-stained placenta images, as well as TOD and MOD values of H&E-stained colonic mucosa images, with the values calculated for the sSTI, increased following image correction. CONCLUSION: These results suggest that histogram transfer depending upon CTIs may be a valuable tool for color correction of tissue section images