Efficiency of neutron tomography in visualizing the internal structure of metal artefacts from Mapungubwe museum collection with the aim of conservation

To aid conservation management of metal artefacts improved knowledge of the internal structure and degree of corrosion therein is highly desired. In this study, neutron- and X-ray tomography were chosen as two complementary noninvasive visualization techniques to study internal structure and corrosion of five representative examples of archaeological metal artefacts from the Mapungubwe museum collection. Tomography was performed at the Neutron Radiography (SANRAD) facility of the South African Nuclear Energy Corporation where thermal neutrons as well as complementary X-rays are conveniently available under one roof. Comparative studies revealed neutron tomography to be generally superior to X-ray tomography due to the enhanced penetration properties of neutrons through the metal objects. In this paper the rich capability of neutron tomography as a nondestructive visualization aid for scientific conservation purposes is introduced and supported by results achieved for the five selected real artefacts.http://www.sciencedirect.com/science/journal/12962074cp201

Global Retinoblastoma Presentation and Analysis by National Income Level

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4) were female. Most patients (n = 3685 84.7%) were from low-and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 62.8%), followed by strabismus (n = 429 10.2%) and proptosis (n = 309 7.4%). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 95% CI, 12.94-24.80, and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 95% CI, 4.30-7.68). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs. © 2020 American Medical Association. All rights reserved

Evidence for indigenous strip-drawing in production of wire at Mapungubwe Hill (1220-1290 AD) : towards an interdisciplinary approach

Several cupreous conical tubes with unclear function are among some of the finds in the collections held at the University of Pretoria which were unearthed by archaeologists on Mapungubwe Hill. Most of these are poorly provenanced, particularly those connected with the activities of Guy Gardner (1935-1940) regarding the waste in northern dump. However, a redetermination of the context following the excavations of the 1970s suggests the funnels date to the period of the rise and development of Mapungubwe as a town and centre of a powerful state. The results from neutron tomography, stereomicroscope and SEM-EDS indicate that the tubes were most probably used in iron strip-drawing to produce wire.http://www.elsevier.com/locate/jascp201

Diatomáceas perifíticas dos arroios Sampaio e Sampainho, Rio Grande do Sul, Brasil Periphitic diatoms from Sampaio and Sampainho streams, Rio Grande do Sul, Brazil

Estudo taxonômico de diatomáceas perifíticas em substrato artificial (fio de poliamida) foi realizado nos arroios Sampaio e Sampainho, localizados na Depressão Central do Estado do Rio Grande do Sul. A investigação baseou-se em amostragens mensais, realizadas no período de um ano (julho de 1994 a junho de 1995). Foram identificados, descritos e ilustrados vinte e um táxons infragenéricos, distribuídos em treze gêneros e onze famílias. Achnanthes rupestoides Hohn, Diadesmis brekkaensis (Petersen) D. G. Mann, Navicula tenelloides Hustedt e Placoneis elginensis (Gregory) E. J. Cox são registrados pela primeira vez em ambientes lóticos no Estado.<br>Taxonomic study of periphitic diatoms on an artificial substrate (polyamide threads) was undertaken in the Sampaio and Sampainho streams, that are located in the Depressão Central region of Rio Grande do Sul State. The investigation was based on monthly sampling taken from July 1994 to June 1995. Twenty one infrageneric taxa distributed in thirteen genera and eleven families were identified, described and illustrated. Achnanthes rupestoides Hohn, Diadesmis brekkaensis (Petersen) D. G. Mann, Navicula tenelloides Hustedt and Placoneis elginensis (Gregory) E. J. Cox are registered for the first time in lotic environments in this state