Über periodische und säkulare Schwankungen der Gewitterhäufigkeit auf der Erde

Zusammenfassung Die statistische Untersuchung mittels des ²-Tests über den Zusammenhang zwischen Gewittertätigkeit und Sonnenaktivität und die Realität desselben führt zu dem Ergebnis, daß nur in 40,9% der betrachteten Stationen mit großer Wahrscheinlichkeit auf einen Zusammenhang geschlossen werden darf. Diese Stationen umfassen vor allem Berg- und Küstenstationen, daher scheint ein Zusammenhang—wenn überhaupt—dann für Wärme- und orographische Gewitter zu bestehen und zwar vor allem in den Tropen und Gebieten nördlich von 55°N. Dabei fallen die Extremwerte der verschiedenen Stationen in ganz verschiedene Jahre innerhalb des Fleckenzyklus, was durchaus kein Argument für einen reellen Zusammenhang der beiden Phänomene ist.Betrachtungen einer 26 tägigen Periode zeigen, daß wohl einige Tage dieser Periode besonders gewitterreich oder gewitterarm sind, doch schwanken die Vorzeichen der Abweichungen vom Mittelwert ziemlich unregelmäßig. Da außerdem eine Ähnlichkeit zwischen den Gängen in den einzelnen Stationen nicht besteht, dürfte die Periode nicht reell sein. Die Betrachtung der säkularen Änderung der Gewitterhäufigkeiten zeigt, daß die Gewittertätigkeit im großen und ganzen zunahm. Die starke Zunahme vor der Jahrhundertwende kann wohl durch genauere Beobachtung erklärt werden. Im letzten Jahrzehnt ist ein Rückgang der Gewittertätigkeit in Europa festzustellen.Aus Vergleichen mit den Resultaten früherer Untersuchungen über dasselbe Thema geht hervor, daß die kurzen Beobachtungsreihen und das Fehlen statistischer Realitätsprüfungsmethoden die betreffenden Autoren zu Schlüssen veranlaßten, die sich bei Verlängerung der Beobachtungsreihen nicht aufrechterhalten ließen. Besonders die behaupteten kurzen Perioden heilten den statistischen Kriterien nicht stand.

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Summary A statistical investigation carried out by the ²-test on the relation between thunderstorm activity and solar activity, and its reality, leads to the result that such a relation can be concluded with high probability in only 40,9 per cent of the considered stations being predominantly mountain and coastal stations. Therefore, a relation—if there is any at all—seems to exist for thermic and orographic thunderstorms, and particularly in the tropics and in the regions north of 55° N. The extreme values of different stations were found in quite different years of the sunspot cycle which is by no means an argument for a real relation of the two phenomena.Considerations of a 26 day period show that some days of the period are either especially rich or poor in thunderstorms, the signs of deviations from the mean value, however, vary rather irregularly. Moreover, as there is no similarity between the records of different stations the period does not seem to be a real one. The study of the secular variation of thunderstorm frequencies shows a general increase of thunderstorm activity. The strong increase at the end of the last century may be explained by better observations, though. During the last decade, a decrease of thunderstorm activity in Europe was found.Comparisons with results of former investigations on the same problem reveal that the short series of observations and the lack of statistical test of reality led authors to conclusions which could not be maintained any more when the series of observations were extended. In particular, the alleged short periods did not hold when tested by statistical criterions.

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Résumé L'étude statistique au moyen du test ² de la relation entre l'activité orageuse et celle des taches solaires montre que le 40,9% seulement des stations considérées fournit une grande probabilité de l'existence d'une telle relation. Il s'agit surtout de stations de montagne et de littoral, de sorte que le relation—si elle existe—concernerait apparemment les orages locaux et de littoral, cela surtout sous les tropiques et dans les régions situées au Nord du 55ème parallèle N. Toutefois les valeurs extrêmes des différentes stations apparaissent dans des années différentes du cycle des taches solaires, ce qui n'est pas un argument en faveur d'une relation réelle entre les deux phénomènes.En ce qui concerne une périodicité de 26 jours, il y a bien certains jours dans cette période plus riches et d'autres plus pauvres en orages, mais les écarts par rapport à la moyenne sont assez irréguliers. Et comme de plus il n'y a pas d'analogie entre les courbes de fréquence des différentes stations, cette période ne semble pas être réelle. Du point de vue de la variation séculaire, l'activité organeuse a augmenté dans l'ensemble. Le fort accroissement de fréquence à la fin du siècle passé peut s'expliquer par des observations meilleures à ce moment là. Pendant la dernière décade, l'activité orageuse en Europe a diminué.Des comparaisons avec des recherches antérieures sur le même sujet montrent que des séries trop courtes d'observations et l'absence de tests statistiques ont parfois conduit les auteurs à des conclusions que la prolongation des séries ne permet pas de maintenir. Les prétendues périodes courtes en particulier sont réduites à néant par les critères statistiques.

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The Alpine Seed Conservation and Research Network–a new initiative to conserve valuable plant species in the European Alps

Safeguarding plants as seeds in ex situ collections is a cost effective element in an integrated plant conservation approach. The European Alps are a regional centre of plant diversity. Six institutions have established a regional network covering the European Alps which will conserve at least 500 priority plant species and which will improve the conservation status of plant species in grassland communities in the subalpine, alpine and nival altitudinal belts. Targeted research will expand the knowledge of the ecology of target species. Public engagement activities will raise the awareness for the importance of specific conservation actions in the European Alps.     

Copper- and iron-induced injuries in roots and rhizomes of reed (Phragmites australis)

About 1 mg/g dw Cu²⁺ and 8 mg/g dw Fe²⁺ were found in roots of reed plants when fed with heavy metal concentrations of 100 μM Cu²⁺ and 10 mM Fe²⁺ under hypoxia. Roots seemed to act as a kind of filter since the amounts in rhizomes were only 0.06 mg Cu²⁺/g dw and 2 mg Fe²⁺/g dw. Increased contents of both ions reduced posthypoxic respiration capacity by 40–50% and also the sum of adenylates (ATP, ADP, AMP) by the same order of magnitude, although energy charge values remained above 0.85 in Cu²⁺ and 0.79 in Fe²⁺ treatments. Energy metabolism of rhizomes was not affected. Copper and iron contents of roots as well as of rhizomes were high enough to induce oxidative stress when roots were fed with 40 μM Cu²⁺ and 1 mM Fe²⁺, respectively.From our results we conclude that increased, but environmentally attainable, amounts of copper and reduced iron ions disturb root energy metabolism, and therefore root functioning and development. Latent injuries, based on oxidative stress, may be harmful for roots and rhizomes under long term exposure.     

Disc heating in NGC 2985

Various processes have been proposed to explain how galaxy discs acquire their thickness. A simple diagnostic for ascertaining this 'heating' mechanism is provided by the ratio of the vertical to radial velocity dispersion components. In a previous paper we have developed a technique for measuring this ratio, and demonstrated its viability on the Sb system NGC 488. Here we present follow-up observations of the morphologically similar Sab galaxy NGC 2985, still only the second galaxy for which this ratio has been determined outside the solar neighbourhood. The result is consistent with simple disc-heating models that predict ratios of σ _z σ _R less than one.     

Automatic detection and tracking of pedestrians from a moving stereo rig

We report on a stereo system for 3D detection and tracking of pedestrians in urban traffic scenes. The system is built around a probabilistic environment model which fuses evidence from dense 3D reconstruction and image-based pedestrian detection into a consistent interpretation of the observed scene, and a multi-hypothesis tracker to reconstruct the pedestrians’ trajectories in 3D coordinates over time. Experiments on real stereo sequences recorded in busy inner-city scenarios are presented, in which the system achieves promising results.     

Temporal distributions of anthropogenic Al, Zn and Pb in Hong Kong Porites coral during the last two centuries

A 182-year long record of trace metal concentrations of aluminum, zinc and lead was reconstructed from a massive Porites coral skeleton from southeastern Hong Kong to evaluate the impacts of anthropogenic activity on the marine environment. Zn/Ca and Pb/Ca ratios fluctuate synchronously from the early 19th century to the present, indicating that the marine environment has been anthropogenically influenced since industrialization. Additionally, land reclamation, mining, and ship building activities are recorded by elevated Al/Ca ratios from 1900 to 1950. The coral record indicates that high levels of Zn, Pb and Al occur coincidentally with local wars, and may have contributed to partial colony mortality. Pb/Ca does not correlate well with hemispheric proxy records after 1950, indicating that coastal corals may be recording local rather than hemispheric contamination. Pb/Ca levels in Hong Kong, Guangdong and Hainan corals imply a continuous supply of Pb-based contamination to southern China not reflected in hemispheric signals.     

Model-independent measurements of bar pattern speeds

The pattern speed is one of the fundamental parameters that determines the structure of barred galaxies. This quantity is usually derived from indirect methods or by employing model assumptions. The number of bar pattern speeds derived using the model-independent Tremaine & Weinberg technique is still very limited. We present the results of model-independent measurements of the bar pattern speed in four galaxies ranging in Hubble type from SB0 to SBbc. Three of the four galaxies in our sample are consistent with bars being fast rotators. The lack of slow bars is consistent with previous observations and suggests that barred galaxies do not have centrally concentrated dark matter haloes. This contradicts simulations of cosmological structure formation and observations of the central mass concentration in nonbarred galaxies.     

Geochemical features of re-deposited organic matter occurring in fluvioglacial sediments in the Racibórz region (Poland): A case study

The erosion of rocks rich in organic matter typically leads to the complete mineralization of the organic material. However, in some cases, it is re-deposited to become a part of sediments once more. This process should be considered to be a part of global carbon cycle, possibly much more significant than assumed to-date. The research presented here aims to characterize re-worked organic matter occurring in post-glacial sediments of southern part of Poland, in the Oder river valley (the Racibórz town region, Miocene, Pleistocene and Holocene age). Organic substances extracted from the sediments originated from organic matter that had resided in rocks eroded by glaciers. Sediments were sampled in two boreholes which sediments were correlated. Sediments were extracted and extracts analyzed with gas chromatography-mass spectrometry (GC-MS) to assess distributions of biomarker groups. Organic matter of selected samples was pre-concentrated and analyzed with Py/GC-MS. In the extracts several biomarker parameters of source/environment and thermal maturity were calculated. Organic substances in the investigated sediments come from variable re-deposited organic matter occurring in rocks eroded by glaciers. Three main parent types of re-deposited organic material are identified showing variable geochemical features: 1) organic matter of recent or almost recent age being the source of polar labile compounds; probably formed in situ, 2) re-deposited organic matter of the middle diagenesis showing features similar to lignites (huminite reflectance Rf ~ 0.25–0.35%) deriving from angiosperm remains, mainly monocotyledons and to the lower extend also deciduous trees, 3) re-deposited organic matter at the middle catagenesis (Rf ~ 0.65–0.75%) being the source of most of aromatic hydrocarbons and biomarkers such as steranes, hopanes of the more thermally advanced distribution type. Its geochemical properties and assumed directions of sediment transport indicate bituminous coals of Upper Silesian Coal Basin together with coaly shales as a possible source of this organic matter. Such mixed origin of organic matter caused large discrepancies in values of thermal maturity parameters depending on input from the particular sources and occurrence both geochemical biomarkers and their biochemical precursors in the same samples.