14 research outputs found

    Sr isotope stratigraphy across the Paasivaara PGE reef of the Penikat intrusion, Northern Finland:insights into the genesis of reef-type PGE mineralization

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    Abstract. Layered mafic-ultramafic intrusions host the largest reserves of feasible PGE commodities. Worldwide rare in the geological record, these deposits are well-constrained in a few large igneous provinces. Despite extensive research on layered intrusions and related PGE ores, the models regarding the PGE ore-formation are diverse, involving both magmatic and hydrothermal processes, and the subject remains largely debatable. In Europe, research efforts around the Baltic Large Igneous Province (BLIP) has doubled due to the new geopolitical strategy of the European Union in their search for new sources of critical metals. Global politics have placed Finnish mafic-ultramafic layered intrusions in the spotlight. Penikat is a Paleoproterozoic 2.44 Ga layered intrusion part of the east-west trending Tornio-N√§r√§nk√§vaara belt in northern Finland. The exposed intrusion is 23 km long and 1.5 km to 3.5 km on the current erosional level. Based on seismic and gravimetric data, it extends to 2.5 km deep. The intrussion is split into five westward-dipping blocks: Sompuj√§rvi, Kilkka, Yli-Penikka, Keski-Penikka, and Ala-Penikka. Traditionally, Penikat is divided into five megacyclic units (MCU I-MCU V), hosting three main PGE reef horizons: the Sompuj√§rvi Reef (SJ), located to the basal part of MCU IV; the Ala-Penikka Reef (AP), occurring within the lower proportion of unit IV; and the Paasivaara Reef (PV), which defines the hanging wall contact from the MCU IV to the MCU V. The present study comprises 700 m of stratigraphy in the Ala-Penikka block and focuses on the Paasivaara reef (PV). This platinum-enriched reef appears at the Transition Zone (TZ), along the MCU IV-V boundary. To gain new insight into Penikat‚Äôs petrogenesis, we utilize fourteen thick section samples from historic drill cores, both intersecting the PV reef, and two additional samples made after hand specimens. The sections were reviewed using petrologic microscopy before subjecting them to geochemical analyses. From these sections, we obtained new in-situ Sr isotope data in plagioclase grains by using the LA-MC-ICP-MS laser ablation technique at the GTK facilities in Espoo, Finland. The procedure can track sub-grain scale heterogeneities from core to rim. As radiogenic ratios are rarely affected by melting or crystallization, subgrain analyses are a powerful tool for tracing the contributors in a magmatic system. In addition, EPMA was used to analyze the plagioclase composition, with dedicated attention to the anorthite content in the assayed grains, at the University of Oulu, Finland. The anorthite content analysis was then compared to the LA-MC-ICP-MS results to assess the magmatic differentiation undergone by the plagioclase crystals. The results support crystallization stability in most of MCU IV (Sr(i) ~ 0.7027 ¬Ī 0.0005) and MCU V (Sr(i) 0.7032 ¬Ī 0.0005 ). Nonetheless, data record a systematic, gradual increase in radiogenic Sr signature in the sparsely 38 m between MCU IV and V. In addition, rim to core distributions register more than a single Sr(i) signature at a subgrain scale in TZ samples. The variability in the Sr signature at the Transition Zone converges with a sharp An86 content spike at the PV reef boundary, arguing for a primitive magma contributor. The results confirm affinity between the SHMB type magma, related to plume magmatism, and the parental magma of Penikat. The Transition Zone would be a product of binary and asymmetric magma mixing, each with contrasting isotopic lineages and varying degrees of crustal contamination. The discussion supports magma ascension from a staging chamber as a likely origin of the PV reef, thus supporting the new magma pulse hypothesis. Finally, the present study is compared with previous Sr(i) stratigraphy in Bushveld, showing similarities between the UPZ-MZ transition and the Transition Zone in Penikat. The detection of similar Sr(i) may lead to new PGE discoveries in the future

    The impact of surgical delay on resectability of colorectal cancer: An international prospective cohort study

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    AIM: The SARS-CoV-2 pandemic has provided a unique opportunity to explore the impact of surgical delays on cancer resectability. This study aimed to compare resectability for colorectal cancer patients undergoing delayed versus non-delayed surgery. METHODS: This was an international prospective cohort study of consecutive colorectal cancer patients with a decision for curative surgery (January-April 2020). Surgical delay was defined as an operation taking place more than 4‚ÄČweeks after treatment decision, in a patient who did not receive neoadjuvant therapy. A subgroup analysis explored the effects of delay in elective patients only. The impact of longer delays was explored in a sensitivity analysis. The primary outcome was complete resection, defined as curative resection with an R0 margin. RESULTS: Overall, 5453 patients from 304 hospitals in 47 countries were included, of whom 6.6% (358/5453) did not receive their planned operation. Of the 4304 operated patients without neoadjuvant therapy, 40.5% (1744/4304) were delayed beyond 4‚ÄČweeks. Delayed patients were more likely to be older, men, more comorbid, have higher body mass index and have rectal cancer and early stage disease. Delayed patients had higher unadjusted rates of complete resection (93.7% vs. 91.9%, P¬†=¬†0.032) and lower rates of emergency surgery (4.5% vs. 22.5%, P‚ÄČ<‚ÄČ0.001). After adjustment, delay was not associated with a lower rate of complete resection (OR 1.18, 95% CI 0.90-1.55, P¬†=¬†0.224), which was consistent in elective patients only (OR 0.94, 95% CI 0.69-1.27, P¬†=¬†0.672). Longer delays were not associated with poorer outcomes. CONCLUSION: One in 15 colorectal cancer patients did not receive their planned operation during the first wave of COVID-19. Surgical delay did not appear to compromise resectability, raising the hypothesis that any reduction in long-term survival attributable to delays is likely to be due to micro-metastatic disease

    Global, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990‚Äď2017: A systematic analysis for the Global Burden of Disease Study 2017

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    Background: The Global Burden of Diseases, Injuries, and Risk Factors Study 2017 (GBD 2017) includes a comprehensive assessment of incidence, prevalence, and years lived with disability (YLDs) for 354 causes in 195 countries and territories from 1990 to 2017. Previous GBD studies have shown how the decline of mortality rates from 1990 to 2016 has led to an increase in life expectancy, an ageing global population, and an expansion of the non-fatal burden of disease and injury. These studies have also shown how a substantial portion of the world's population experiences non-fatal health loss with considerable heterogeneity among different causes, locations, ages, and sexes. Ongoing objectives of the GBD study include increasing the level of estimation detail, improving analytical strategies, and increasing the amount of high-quality data. Methods: We estimated incidence and prevalence for 354 diseases and injuries and 3484 sequelae. We used an updated and extensive body of literature studies, survey data, surveillance data, inpatient admission records, outpatient visit records, and health insurance claims, and additionally used results from cause of death models to inform estimates using a total of 68 781 data sources. Newly available clinical data from India, Iran, Japan, Jordan, Nepal, China, Brazil, Norway, and Italy were incorporated, as well as updated claims data from the USA and new claims data from Taiwan (province of China) and Singapore. We used DisMod-MR 2.1, a Bayesian meta-regression tool, as the main method of estimation, ensuring consistency between rates of incidence, prevalence, remission, and cause of death for each condition. YLDs were estimated as the product of a prevalence estimate and a disability weight for health states of each mutually exclusive sequela, adjusted for comorbidity. We updated the Socio-demographic Index (SDI), a summary development indicator of income per capita, years of schooling, and total fertility rate. Additionally, we calculated differences between male and female YLDs to identify divergent trends across sexes. GBD 2017 complies with the Guidelines for Accurate and Transparent Health Estimates Reporting. Findings: Globally, for females, the causes with the greatest age-standardised prevalence were oral disorders, headache disorders, and haemoglobinopathies and haemolytic anaemias in both 1990 and 2017. For males, the causes with the greatest age-standardised prevalence were oral disorders, headache disorders, and tuberculosis including latent tuberculosis infection in both 1990 and 2017. In terms of YLDs, low back pain, headache disorders, and dietary iron deficiency were the leading Level 3 causes of YLD counts in 1990, whereas low back pain, headache disorders, and depressive disorders were the leading causes in 2017 for both sexes combined. All-cause age-standardised YLD rates decreased by 3·9% (95% uncertainty interval [UI] 3·1-4·6) from 1990 to 2017; however, the all-age YLD rate increased by 7·2% (6·0-8·4) while the total sum of global YLDs increased from 562 million (421-723) to 853 million (642-1100). The increases for males and females were similar, with increases in all-age YLD rates of 7·9% (6·6-9·2) for males and 6·5% (5·4-7·7) for females. We found significant differences between males and females in terms of age-standardised prevalence estimates for multiple causes. The causes with the greatest relative differences between sexes in 2017 included substance use disorders (3018 cases [95% UI 2782-3252] per 100 000 in males vs 1400 [1279-1524] per 100 000 in females), transport injuries (3322 [3082-3583] vs 2336 [2154-2535]), and self-harm and interpersonal violence (3265 [2943-3630] vs 5643 [5057-6302]). Interpretation: Global all-cause age-standardised YLD rates have improved only slightly over a period spanning nearly three decades. However, the magnitude of the non-fatal disease burden has expanded globally, with increasing numbers of people who have a wide spectrum of conditions. A subset of conditions has remained globally pervasive since 1990, whereas other conditions have displayed more dynamic trends, with different ages, sexes, and geographies across the globe experiencing varying burdens and trends of health loss. This study emphasises how global improvements in premature mortality for select conditions have led to older populations with complex and potentially expensive diseases, yet also highlights global achievements in certain domains of disease and injury

    Global, regional, and national age-sex-specific mortality and life expectancy, 1950-2017: a systematic analysis for the Global Burden of Disease Study 2017

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    Background: Assessments of age-specific mortality and life expectancy have been done by the UN Population Division, Department of Economics and Social Affairs (UNPOP), the United States Census Bureau, WHO, and as part of previous iterations of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD). Previous iterations of the GBD used population estimates from UNPOP, which were not derived in a way that was internally consistent with the estimates of the numbers of deaths in the GBD. The present iteration of the GBD, GBD 2017, improves on previous assessments and provides timely estimates of the mortality experience of populations globally. Methods: The GBD uses all available data to produce estimates of mortality rates between 1950 and 2017 for 23 age groups, both sexes, and 918 locations, including 195 countries and territories and subnational locations for 16 countries. Data used include vital registration systems, sample registration systems, household surveys (complete birth histories, summary birth histories, sibling histories), censuses (summary birth histories, household deaths), and Demographic Surveillance Sites. In total, this analysis used 8259 data sources. Estimates of the probability of death between birth and the age of 5 years and between ages 15 and 60 years are generated and then input into a model life table system to produce complete life tables for all locations and years. Fatal discontinuities and mortality due to HIV/AIDS are analysed separately and then incorporated into the estimation. We analyse the relationship between age-specific mortality and development status using the Socio-demographic Index, a composite measure based on fertility under the age of 25 years, education, and income. There are four main methodological improvements in GBD 2017 compared with GBD 2016: 622 additional data sources have been incorporated; new estimates of population, generated by the GBD study, are used; statistical methods used in different components of the analysis have been further standardised and improved; and the analysis has been extended backwards in time by two decades to start in 1950. Findings: Globally, 18¬∑7% (95% uncertainty interval 18¬∑4‚Äď19¬∑0) of deaths were registered in 1950 and that proportion has been steadily increasing since, with 58¬∑8% (58¬∑2‚Äď59¬∑3) of all deaths being registered in 2015. At the global level, between 1950 and 2017, life expectancy increased from 48¬∑1 years (46¬∑5‚Äď49¬∑6) to 70¬∑5 years (70¬∑1‚Äď70¬∑8) for men and from 52¬∑9 years (51¬∑7‚Äď54¬∑0) to 75¬∑6 years (75¬∑3‚Äď75¬∑9) for women. Despite this overall progress, there remains substantial variation in life expectancy at birth in 2017, which ranges from 49¬∑1 years (46¬∑5‚Äď51¬∑7) for men in the Central African Republic to 87¬∑6 years (86¬∑9‚Äď88¬∑1) among women in Singapore. The greatest progress across age groups was for children younger than 5 years; under-5 mortality dropped from 216¬∑0 deaths (196¬∑3‚Äď238¬∑1) per 1000 livebirths in 1950 to 38¬∑9 deaths (35¬∑6‚Äď42¬∑83) per 1000 livebirths in 2017, with huge reductions across countries. Nevertheless, there were still 5¬∑4 million (5¬∑2‚Äď5¬∑6) deaths among children younger than 5 years in the world in 2017. Progress has been less pronounced and more variable for adults, especially for adult males, who had stagnant or increasing mortality rates in several countries. The gap between male and female life expectancy between 1950 and 2017, while relatively stable at the global level, shows distinctive patterns across super-regions and has consistently been the largest in central Europe, eastern Europe, and central Asia, and smallest in south Asia. Performance was also variable across countries and time in observed mortality rates compared with those expected on the basis of development. Interpretation: This analysis of age-sex-specific mortality shows that there are remarkably complex patterns in population mortality across countries. The findings of this study highlight global successes, such as the large decline in under-5 mortality, which reflects significant local, national, and global commitment and investment over several decades. However, they also bring attention to mortality patterns that are a cause for concern, particularly among adult men and, to a lesser extent, women, whose mortality rates have stagnated in many countries over the time period of this study, and in some cases are increasing

    Oldowan stone knapping and percussive activities on a raw material reservoir deposit 1.4 million years ago at Barranco León (Orce, Spain)

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