New insights into the magmatic-hydrothermal system and volatile budget of Lastarria volcano, Chile: Integrated results from the 2014 IAVCEI CCVG 12th Volcanic Gas Workshop.

Recent geophysical evidence for large-scale regional crustal inflation and localized crustal magma intrusion has made Lastarria volcano (northern Chile) the target of numerous geological, geophysical, and geochemical studies. The chemical composition of volcanic gases sampled during discrete campaigns from Lastarria volcano indicated a well-developed hydrothermal system from direct fumarole samples in A.D. 2006, 2008, and 2009, and shallow magma degassing using measurements from in situ plume sampling techniques in 2012. It is unclear if the differences in measured gas compositions and resulting interpretations were due to artifacts of the different sampling methods employed, short-term excursions from baseline due to localized changes in stress, or a systematic change in Lastarria's magmatic-hydrothermal system between 2009 and 2012. Integrated results from a two-day volcanic gas sampling and measurement campaign during the 2014 International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) Commission on the Chemistry of Volcanic Gases (CCVG) 12th Gas Workshop are used here to compare and evaluate current gas sampling and measurement techniques, refine the existing subsurface models for Lastarria volcano, and provide new constraints on its magmatic-hydrothermal system and total degassing budget. While compositional differences among sampling methods are present, distinct compositional changes are observed, which if representative of longterm trends, indicate a change in Lastarria's overall magmatic-hydrothermal system. The composition of volcanic gases measured in 2014 contained high proportions of relatively magma- and water-soluble gases consistent with degassing of shallow magma, and in agreement with the 2012 gas composition. When compared with gas compositions measured in 2006-2009, higher relative H2O/CO2 ratios combined with lower relative CO2/St and H2O/St and stable HCl/St ratios (where St is total S [SO2 + H2S]) are observed in 2012 and 2014. These compositional changes suggest variations in the magmatic-hydrothermal system between 2009 and 2012, with possible scenarios to explain these trends including: (1) decompression-induced degassing due to magma ascent within the shallow crust; (2) crystallization-induced degassing of a stalled magma body; (3) depletion of the hydrothermal system due to heating, changes in local stress, and/or minimal precipitation; and/or (4) acidification of the hydrothermal system. These scenarios are evaluated and compared against the geophysical observations of continuous shallow inflation at ~8 km depth between 1997 and 2016, and near-surface ( < 1 km) inflation between 2000 and 2008, to further refine the existing subsurface models. Higher relative H2O/CO2 observed in 2012 and 2014 is not consistent with the depletion or acidification of a hydrothermal system, while all other observations are consistent with the four proposed models. Based on these observations, we find that scenarios 1 or 2 are the most likely to explain the geochemical and geophysical observations, and propose that targeted shallow interferometric synthetic-aperture radar (InSAR) studies could help discriminate between these two scenarios. Lastly, we use an average SO2 flux of 604 \ub1 296 t/d measured on 22 November 2014, along with the average gas composition and diffuse soil CO2 flux measurements, to estimate a total volatile flux from Lastarria volcano in 2014 of ~12,400 t/d, which is similar to previous estimates from 2012

Malaria control in East Africa: the Kampala Conference and the Pare-Taveta Scheme: a meeting of common and high ground.

The 1950 Malaria Conference in Equatorial Africa, held in Kampala, Uganda, has been remembered primarily for its decision to control malaria '...by modern methods as soon as feasible, whatever the original degree of endemicity, and without awaiting the outcome of further experiments.' This decision was far from conclusive and, indeed, reflects only one side of the argument which brought two groups of malariologists into direct opposition on the wisdom of malaria control in equatorial Africa, using modern methods such as DDT. Through an examination of the unpublished verbatim transcript of the Kampala Conference, we are able to document the 'furious debates' which took place at Kampala in 1950. We highlight, in particular, the adamant concerns expressed by some of the delegates that intervention in areas of high malaria transmission might lead to a loss of naturally acquired immunity which, in turn, could give rise to a resurgence of malaria, should the control strategies fail to be sustained. As we show, this concern had been expressed by a number of malariologists working in East Africa in the first half of the twentieth century, but it was only with the advent of DDT, as a residual insecticide, that the implications of wide-spread control, in the absence of any knowledge of the long-term consequences, became a serious possibility. While the Kampala Conference gave the 'go ahead' to control malaria in Africa without awaiting the outcome of 'further experiments', a number of participants insisted that a field trial should be set up to evaluate the impact of malaria on areas of high transmission both before and after spraying: to this end, a field trial in Pare-Taveta was carried out in 1954-59. In this paper we look at the Kampala Conference for its scientific debates and the Pare-Taveta Scheme for its field applications. In the final part of the paper, we address a number of questions raised at Kampala which have, once more, become contentious issues, following the recent successful trials of ITBNs. We believe that an understanding of the historical foundations of these issues should provide an important component of the new WHO campaign to Roll Back Malaria

THE EAST AFRICAN MEDICAL JOURNAL: ITS HISTORY AND CONTRIBUTION TO REGIONAL MALARIA RESEARCH DURING THE LAST 75 YEARS.

Since its inception seventy five years ago, the East African Medical Journal has provided an uninterrupted forum through which medical practitioners and scientists could publish their research. Although the EAMJ was initially prepared for an audience of colonial medical officers, by the 1930s the journal expanded to include subscription and submissions from Northern Rhodesia (now Zimbabwe) and West Africa. Our review begins with a history of the journal's production, exploring the shifts in editorial composition. We then focus more directly on a discussion of papers and editorials on malaria, a disease that continues to challenge the region of East Africa. Our review highlights the importance of the journal's commitment to publications on this major health problem within the East African environment. Of particular interest, our review shows that many of today's concerns, debates and recommendations for control or treatment of malaria in East Africa were discussed and debated in earlier issues of the EAMJ. Medical policy for the region with regard to malaria will benefit from revisiting previous volumes of the EAMJ. These contributions will ensure the journal a significant place in the world of research publications for the coming seventy five years

Stability and bearing capacity of arch-shaped corrugated shell elements: experimental and numerical study

The paper presents problems related to the numerical modeling of profiled steel sheets used as self-supporting arch structures for roof covering. The rules of preparing and full analysis of a set of numerical models of these elements with a different level of complexity are given. The models are evaluated by comparing numerical results with the results of extended experimental tests performed by 3D Digital Image Correlation (DIC) method. For each model the comparison of numerical and experimental results has been made for samples of a single-wave trapezoidal profile with corrugated web and lower flanges subjected to compression and bending. The full-field analysis allows to determine the allowed simplification of numerical models which do not affect in significant way the reliability of the results. The proposed methodology is the first step in the development of full assessment methodology for different types of self-supporting arch structures produced by ABM technology

Application of Image Based Methods for Monitoring and Measurements of Structures in Power Stations

score: 8collation: 24-3