Clusters of galaxies: setting the stage

Clusters of galaxies are self-gravitating systems of mass ~10^14-10^15 Msun. They consist of dark matter (~80 %), hot diffuse intracluster plasma (< 20 %) and a small fraction of stars, dust, and cold gas, mostly locked in galaxies. In most clusters, scaling relations between their properties testify that the cluster components are in approximate dynamical equilibrium within the cluster gravitational potential well. However, spatially inhomogeneous thermal and non-thermal emission of the intracluster medium (ICM), observed in some clusters in the X-ray and radio bands, and the kinematic and morphological segregation of galaxies are a signature of non-gravitational processes, ongoing cluster merging and interactions. In the current bottom-up scenario for the formation of cosmic structure, clusters are the most massive nodes of the filamentary large-scale structure of the cosmic web and form by anisotropic and episodic accretion of mass. In this model of the universe dominated by cold dark matter, at the present time most baryons are expected to be in a diffuse component rather than in stars and galaxies; moreover, ~50 % of this diffuse component has temperature ~0.01-1 keV and permeates the filamentary distribution of the dark matter. The temperature of this Warm-Hot Intergalactic Medium (WHIM) increases with the local density and its search in the outer regions of clusters and lower density regions has been the quest of much recent observational effort. Over the last thirty years, an impressive coherent picture of the formation and evolution of cosmic structures has emerged from the intense interplay between observations, theory and numerical experiments. Future efforts will continue to test whether this picture keeps being valid, needs corrections or suffers dramatic failures in its predictive power.Comment: 20 pages, 8 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 2; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke

State of the climate in 2013

In 2013, the vast majority of the monitored climate variables reported here maintained trends established in recent decades. ENSO was in a neutral state during the entire year, remaining mostly on the cool side of neutral with modest impacts on regional weather patterns around the world. This follows several years dominated by the effects of either La Niña or El Niño events. According to several independent analyses, 2013 was again among the 10 warmest years on record at the global scale, both at the Earths surface and through the troposphere. Some regions in the Southern Hemisphere had record or near-record high temperatures for the year. Australia observed its hottest year on record, while Argentina and New Zealand reported their second and third hottest years, respectively. In Antarctica, Amundsen-Scott South Pole Station reported its highest annual temperature since records began in 1957. At the opposite pole, the Arctic observed its seventh warmest year since records began in the early 20th century. At 20-m depth, record high temperatures were measured at some permafrost stations on the North Slope of Alaska and in the Brooks Range. In the Northern Hemisphere extratropics, anomalous meridional atmospheric circulation occurred throughout much of the year, leading to marked regional extremes of both temperature and precipitation. Cold temperature anomalies during winter across Eurasia were followed by warm spring temperature anomalies, which were linked to a new record low Eurasian snow cover extent in May. Minimum sea ice extent in the Arctic was the sixth lowest since satellite observations began in 1979. Including 2013, all seven lowest extents on record have occurred in the past seven years. Antarctica, on the other hand, had above-average sea ice extent throughout 2013, with 116 days of new daily high extent records, including a new daily maximum sea ice area of 19.57 million km2 reached on 1 October. ENSO-neutral conditions in the eastern central Pacific Ocean and a negative Pacific decadal oscillation pattern in the North Pacific had the largest impacts on the global sea surface temperature in 2013. The North Pacific reached a historic high temperature in 2013 and on balance the globally-averaged sea surface temperature was among the 10 highest on record. Overall, the salt content in nearsurface ocean waters increased while in intermediate waters it decreased. Global mean sea level continued to rise during 2013, on pace with a trend of 3.2 mm yr-1 over the past two decades. A portion of this trend (0.5 mm yr-1) has been attributed to natural variability associated with the Pacific decadal oscillation as well as to ongoing contributions from the melting of glaciers and ice sheets and ocean warming. Global tropical cyclone frequency during 2013 was slightly above average with a total of 94 storms, although the North Atlantic Basin had its quietest hurricane season since 1994. In the Western North Pacific Basin, Super Typhoon Haiyan, the deadliest tropical cyclone of 2013, had 1-minute sustained winds estimated to be 170 kt (87.5 m s-1) on 7 November, the highest wind speed ever assigned to a tropical cyclone. High storm surge was also associated with Haiyan as it made landfall over the central Philippines, an area where sea level is currently at historic highs, increasing by 200 mm since 1970. In the atmosphere, carbon dioxide, methane, and nitrous oxide all continued to increase in 2013. As in previous years, each of these major greenhouse gases once again reached historic high concentrations. In the Arctic, carbon dioxide and methane increased at the same rate as the global increase. These increases are likely due to export from lower latitudes rather than a consequence of increases in Arctic sources, such as thawing permafrost. At Mauna Loa, Hawaii, for the first time since measurements began in 1958, the daily average mixing ratio of carbon dioxide exceeded 400 ppm on 9 May. The state of these variables, along with dozens of others, and the 2013 climate conditions of regions around the world are discussed in further detail in this 24th edition of the State of the Climate series. © 2014, American Meteorological Society. All rights reserved

Sólidos totais do leite em amostras de tanque nos estados do Paraná, Santa Catarina e São Paulo Milk total solids in bulk tank samples of Paraná, Santa Catarina and São Paulo States

Objetivou-se, neste trabalho, estudar a variação dos sólidos totais em amostras de leite de tanques de 32.590 rebanhos dos estados do Paraná, Santa Catarina e São Paulo. Foram analisadas 257.540 amostras de leite de tanques coletadas entre janeiro de 1999 e novembro de 2001, no Laboratório Central do Programa de Análise de Rebanhos Leiteiros do Paraná (PARLPR), da Associação Paranaense de Criadores de Bovinos da Raça Holandesa. Utilizando-se o método dos quadrados mínimos, foram estudados os efeitos de rebanho, região, mês e ano de análise, idade da amostra e escore de células somáticas sobre os sólidos totais, em amostras de leite de tanques. As médias ajustadas dos sólidos totais por região variaram de 11,78 a 12,83%; a maior média foi verificada em maio de 2001 e a menor, em janeiro de 2000; os sólidos totais não demonstraram variação até o quinto dia de análise; o efeito de escore de células somáticas foi contraditório, se comparado aos relatados por outros autores. Todos os fatores incluídos no modelo linear foram altamente significativos sobre as características analisadas. O coeficiente de correlação entre sólidos totais e seus componentes foi de 0,875 para gordura, 0,653 para proteína, 0,237 para lactose, e 0,643 para sólidos não-gordurosos. A correlação de sólidos totais com contagem de células somáticas foi 0,012, e com escore de células somáticas, de 0,023.<br>The objective of this research was to study the variation of total solids in bulk tank milk samples in 32,590 herds of Paraná, Santa Catarina and São Paulo states, in Brazil. A total of 257,540 bulk tank samples collected between January 1999 and November 2001 were analyzed at the Central Laboratory of the Programa de Análise dos Rebanhos Leiteiros do Paraná (PARLPR) of the Holstein Association of the state of Paraná. Least Square Means Method procedures were used to study the effects of herd, region, month and year of test, age of the sample and somatic cell score on total solids of bulk tank milk. The adjusted means of total solids by region ranged from 11.78 to 12.83%; the greatest means were in May 2001 and the smallest in January 2000; total solids did not show variation until the fifth day of analysis; the effect of cell score was contradictory, when compared with other authors. All factors included in the linear model had highly significant effect on the trait analyzed. The correlation coefficient between total solids and their components were 0.875 for fat, 0.653 for protein, 0.237 for lactose, and 0.643 for solids not fat. Correlation of total solids with somatic cell count was 0.012, and 0.023 with somatic cell score