109 research outputs found
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What is the climate system able to do ‘on its own’?
The climate of the Earth, like planetary climates in general, is broadly controlled by solar irradiation, planetary albedo and emissivity as well as its rotation rate and distribution of land (with its orography) and oceans. However, the majority of climate fluctuations that affect mankind are internal modes of the general circulation of the atmosphere and the oceans. Some of these modes, such as El Nino-Southern Oscillation (ENSO), are quasi-regular and have some longer-term predictive skill; others like the Arctic and Antarctic Oscillation are chaotic and generally unpredictable beyond a few weeks. Studies using general circulation models indicate that internal processes dominate the regional climate and that some like ENSO events have even distinct global signatures. This is one of the reasons why it is so difficult to separate internal climate processes from external ones caused, for example, by changes in greenhouse gases and solar irradiation. However, the accumulation of the warmest seasons during the latest two decades is lending strong support to the forcing of the greenhouse gases. As models are getting more comprehensive, they show a gradually broader range of internal processes including those on longer time scales, challenging the interpretation of the causes of past and present climate events further
Analysis of the impact of sex and age on the variation in the prevalence of antinuclear autoantibodies in Polish population: a nationwide observational, cross-sectional study
The detection of antinuclear autoantibody (ANA) is dependent on many factors and varies between the populations. The aim of the study was first to assess the prevalence of ANA in the Polish adult population depending on age, sex and the cutoff threshold used for the results obtained. Second, we estimated the occurrence of individual types of ANA-staining patterns. We tested 1731 patient samples using commercially available IIFA using two cutoff thresholds of 1:100 and 1:160. We found ANA in 260 participants (15.0%), but the percentage of positive results strongly depended on the cutoff level. For a cutoff threshold 1:100, the positive population was 19.5% and for the 1:160 cutoff threshold, it was 11.7%. The most prevalent ANA-staining pattern was AC-2 Dense Fine speckled (50%), followed by AC-21 Reticular/AMA (14.38%) ANA more common in women (72%); 64% of ANA-positive patients were over 50 years of age. ANA prevalence in the Polish population is at a level observed in other highly developed countries and is more prevalent in women and elderly individuals. To reduce the number of positive results released, we suggest that Polish laboratories should set 1:160 as the cutoff threshold
Problemy akustyczne elementów i układów mikrohydraulicznych
This paper presents selected applications of the miniaturized hydraulic components offered by specialized manufacturers and some results of the authors' own research on microflows, including results of hydraulic microfeeder vibration measurements performed by the touchless method using a laser vibrometer. The latter was chosen in order to eliminate measuring instrument influence on the investigated microhydraulic object. Special attention was focused on acoustic problems: noise sources and methods of noise reduction.W pracy przedstawiono wybrane przykłady zastosowań zminiaturyzowanych elementów hydraulicznych proponowanych przez wyspecjalizowanych producentów oraz podano wyniki niektórych prac własnych nad zjawiskami związanymi z mikroprzepływami. W artykule prezentuje się m.in. wyniki pomiarów drgań zaworu przelewowego mikrozasilacza hydraulicznego wykonane za pomocą wibrometru laserowego - metodą bezdotykową. Wykorzystanie do pomiarów w obszarze mikrohydrauliki wibrometru laserowego podyktowane było koniecznością wyeliminowania wpływu przyrządów pomiarowych na badany obiekt. Szczególną uwagę skupiono na problemach akustycznych: źródłach hałasu i metodach jego redukcji
Discussion of ‘The permeability of fly ash concrete’, by M. D. A. Thomas and J. D. Matthews
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