Atmospheric implications of studies of Central American volcanic eruption clouds

During February 1978 a group of scientists from the National Center for Atmospheric Research, several colleges and universities, the U.S. Geological Survey, and NASA used a specially equipped Beech Queen Air aircraft to make 11 sampling flights in Guatemala through the eruption clouds from the volcanoes Pacaya, Fuego, and Santiguito. Measurements were made of SO42−, SO2, HCl, HF, and 11 cations that were in water-soluble form, on samples collected by a specially designed filter pack. Particle size distributions were obtained with a piezoelectric cascade impactor, and the particles were identified by energy dispersive X ray analysis. Evacuated canisters were flown to obtain samples for gas Chromatographic analysis. Some of the conclusions reached are that since most of the sulfur was found to be in the form of SO2, the H2SO4 droplets resulting from major explosive eruptions must largely result from the reaction of SO2 with OH, at the same time depleting the atmosphere of OH; the volume concentration ratio [SO2]/[HCl] always somewhat exceeded unity; and the amount of fine ash remaining in the stratosphere for long periods of time may depend on the crystallinity of the magma. Correlation spectrometry showed that each volcano was emitting 300–1500 metric tons of SO2 per day

Understanding Global Change: From Documentation and Collaboration to Social Transformation

The conclusion to the book situates the chapters within four programs of anthropological research on climate change: (1) documentation of local impacts of and adaptations to climate change, (2) connections to socioeconomic and political contexts, (3) collaborations with nonanthropologists, and (4) activism and social transformation. The final section notes the persistent challenges to creating positive change and meaningful research outcomes. It highlights some examples of success and outlines future directions for politically engaged anthropological work around climate change

Hydrogen Peroxide in the Troposphere

Uloga vodikova peroksida (H2O2) u atmosferskoj kemiji i njegov doprinos u nastanku slobodnih radikala počeli su se proučavati tek posljednjih nekoliko desetljeća. Fotokemijskim reakcijama s ozonom i H2O2 nastaju oksidansi (slobodni radikali) koji mogu oksidirati biomolekule unutar stanica te dovesti do smrti stanica i ozljeda tkiva. Zbog toga se slobodni radikali smatraju uzrokom više od sto bolesti. H2O2 smatra se boljim indikatorom za atmosferski oksidacijski kapacitet od ozona. U atmosferi može biti prisutan u plinovitoj i tekućoj fazi te pokazuje tipične dnevne i sezonske varijacije. Me|utim, zbog skupe i slo`ene opreme, mjerenja H2O2 su rijetka i ograničena na samo nekoliko mjesta u svijetu. Mjerenja u slojevima leda na Grenlandu pokazala su da koncentracije H2O2 rastu posljednjih 200 godina. Značajan porast primijećen je upravo posljednjih dvaju desetljeća, a procjene pokazuju da će i dalje rasti zbog smanjene emisije sumporova dioksida. Mjerenja H2O2 u Hrvatskoj do sada još nisu bila provedena te će uporedo s već postojećim dugogodišnjim rezultatima mjerenja ozona i dušikovih oksida dati uvid u stanje i utjecaj na oksidativni stres.The past few decades saw a rising interest in the role of hydrogen peroxide (H2O2) in atmospheric chemistry and its contribution to the formation of free radicals. Free radicals (oxidants) are formed by photochemical reactions between ozone and H2O2. Free radicals formed within cells can oxidise biomolecules, and this may lead to cell death and tissue injury. For this reason, free radicals are believed to cause more than 100 diseases. H2O2 has been suggested as a better indicator of atmospheric oxidation capacity than ozone. Atmospheric H2O2 can appear in the gas phase or in the aqueous phase. It shows typical diurnal and seasonal variations. However, measurements of H2O2 with expensive and sophisticated equipment are rare and limited to but a few sites in the world. Measurements in Greenland ice cores showed that H2O2 concentrations increased over the last 200 years and most of the increase has occurred over the last 20 years. Evaluations show that concentrations will still rise as a result of decreasing SO2 emission. H2O2 measurements have not been carried out in Croatia until now, and, accompanied by the existing longterm measurements of ozone and nitrogen oxides, they will provide an idea of the oxidative capacity of the atmosphere and its influence on oxidative stress

Identification and Recognition of Vehicle Environment Using Artificial Neural Networks

Object detection using deep learning over the years became one of the most popular methods for implementation in autonomous systems. Autonomous vehicle requires very reliable and accurate identification and recognition of surrounding objects in real traffic environments to achieve decent detection results. In this paper, special type of Artificial Neural Network (ANN) named Convolutional Neural Network (CNN) was used for identification and recognition of surrounding objects in real traffic. The new model based on CNN was trained and developed to be able to identify and recognize 4 different classes of objects: cars, traffic lights, persons and bicycles. The developed model has shown 94.6% accuracy of object identification and recognizing on the test set

SULFUR AND HALOGEN CHEMISTRY OF THE STRATOSPHERE AND OF VOLCANIC ERUPTION PLUMES.

The major eruption of Volcan de Fuego caused an enhancement of 1. 6 multiplied by 10**9 kg of SO//4** minus in the stratosphere 6 months after the eruption. Measurable changes in nitric acid vapor and particulate chloride were not observed. Subsequent data suggests that HCl was not injected into the stratosphere. The first simulataneous measurements of halogen and sulfur content of gases and particles in explosive eruption plumes is reported. The average percents of elements in particles were sulfur, 2. 5 plus or minus 2. 1; chlorine, 18 plus or minus 12; and fluorine, 38 plus or minus 29. The average molecular ratio of HCl/SO//2 and HCl/HF were 0. 41 plus or minus 0. 26 and 14 plus or minus 12 in the Guatemalan eruption plumes