A continental record of the Carnian Pluvial Episode (CPE) from the Mercia Mudstone Group (UK):palynology and climatic implications

The generally arid Late Triassic climate was interrupted by a wet phase during the mid-Carnian termed the Carnian Pluvial Episode (CPE). Quantitative palynological data from the Mercia Mudstone Group in the Wessex Basin (UK) reveal vegetation changes and palaeoclimate trends. Palynostratigraphy and bulk organic carbon isotope data allow correlation to other Carnian successions. The palynostratigraphy indicates that the Dunscombe Mudstone is Julian and the lowest part of the overlying Branscombe Mudstone Formation is Tuvalian. The Aulisporites acme characterizing the CPE in Tethyan successions and the Germanic Basin is missing in the UK. The quantitative palynological record suggests the predominance of xerophyte floral elements with a few horizons of increased hygrophytes. A humidity signal is not seen owing to the dry climate in central Pangea. Also, the signal might be masked by the overrepresentation of xerophyte regional pollen and the predominance of xerophyte hinterland flora. The bias towards regional pollen rain is enhanced by the potential increase in continental runoff related to seasonally humid conditions and differences in pollen production rates and transport mechanisms. The vegetation of British CPE successions suggests a more complex climate history during the Carnian, indicating that the CPE is not recognized by the same changes everywhere

New national and regional bryophyte records, 59

Peer reviewe

Increased diversification rates follow shifts to bisexuality in liverworts

Shifts in sexual systems are one of the key drivers of species diversification. In contrast to angiosperms, unisexuality prevails in bryophytes. Here, we test the hypotheses that bisexuality evolved from an ancestral unisexual condition and is a key innovation in liverworts. We investigate whether shifts in sexual systems influence diversification using hidden state speciation and extinction analysis (HiSSE). This new method compares the effects of the variable of interest to the best-fitting latent variable, yielding robust and conservative tests. We find that the transitions in sexual systems are significantly biased toward unisexuality, even though bisexuality is coupled with increased diversification. Sexual systems are strongly conserved deep within the liverwort tree but become much more labile toward the present. Bisexuality appears to be a key innovation in liverworts. Its effects on diversification are presumably mediated by the interplay of high fertilization rates, massive spore production and long-distance dispersal, which may separately or together have facilitated liverwort speciation, suppressed their extinction, or both. Importantly, shifts in liverwort sexual systems have the opposite effect when compared to angiosperms, leading to contrasting diversification patterns between the two groups. The high prevalence of unisexuality among liverworts suggests, however, a strong selection for sexual dimorphism

Variability of the quasi-2-day wave observed in the MLT region during the PSMOS campaign of June-August 1999

A network of 15 northern hemisphere radars has been used to measure horizontal winds in the mesosphere and lower thermosphere during the PSMOS campaign of Summer 1999. The radars are sited at latitudes ranging from 21°N to 75°N and longitudes from 142°E to 157°W. The data were examined to investigate the Northern Hemisphere structure of the quasi-2-day planetary wave during the interval June-August. The amplitude of the 2-day wave was found to exhibit great day-to-day variability. In particular, significant periodic fluctuations in amplitude occurred with periods of 8-10 and 14-17 days. These modulations were strongest in July and largely absent in June and August. In July, the wave activity can be resolved into three westward-propagating waves with zonal wave numbers of 2, 3 and 4. The periods associated with these wave numbers were 53-56, 48-50 and 42-43 h, respectively. The simultaneous presence of at least two spectral components with periods close to each other may serve to explain the observed amplitude modulations as a result of a beating between different spectral components. An earlier analysis of the planetary-wave field during this interval has revealed a westward propagating ∼16-day wave with zonal wave number 1 (Journal of Atmospheric and Solar-Terrestrial Physics 64 (2002b) 1865-1896). A non-linear interaction between this ∼16-day planetary wave and the (3,0) Rossby-gravity mode (the 2-day-wave) provides a possible mechanism to generate the above ∼42 h/wavenumber 4 wave and the ∼55 h/wavenumber 2 waves as sum and difference secondary waves. A bispectral analysis was used to further investigate non-linear interactions between members of the planetary-wave field and suggested a number of interactions occur within the planetary-wave field, but that some of the interactions also involve the non-migrating diurnal tide with zonal wavenumber 6. © 2004 Elsevier Ltd. All rights reserved

Взаимосвязь показателей кровообращения мышц бедра и плеча с координационной точностью при совершенствовании ударных баллистических движений

В работе была исследована взаимосвязь показателей кровообращения мышц бедра и плеча с координационной точностью при совершенствовании ударных баллистических движений. Для этого было сформировано две группы: в экспериментальной группе в качестве предупреждения травматизма кисти использовались боксерские перчатки (10 унций), а в контрольной - снарядные перчатки. В результате после нанесения одиночного акцентированного прямого удара правой рукой в голову по боксерскому мешку в течение раунда было получено, что в экспериментальной группе происходило увеличение интенсивности кровенаполнения задней поверхности правого бедра и увеличение венозного оттока. Можно предположить, что спортсмены экспериментальной группы больше опираются на правую ногу в заключительной фазе ударного действия, что является более правильно с биомеханической точки зрения нанесения ударов. Интенсивность кровенаполнения и венозного оттока плеча в экспериментальной группе, наоборот, падала. Это позволяет сделать предположение о том, что мышцы плеча при выполнении ударных движений лишь незначительно задействуются спортсменами старших спортивных разрядов в завершающей фазе ударного действия. Данный факт им позволяет наносить удары с большей точностью и эффективностью

Patterns and mechanisms of early Pliocene warmth

About five to four million years ago, in the early Pliocene epoch, Earth had a warm, temperate climate. The gradual cooling that followed led to the establishment of modern temperature patterns, possibly in response to a decrease in atmospheric CO2 concentration, of the order of 100 parts per million, towards preindustrial values. Here we synthesize the available geochemical proxy records of sea surface temperature and show that, compared with that of today, the early Pliocene climate had substantially lower meridional and zonal temperature gradients but similar maximum ocean temperatures. Using an Earth system model, we show that none of the mechanisms currently proposed to explain Pliocene warmth can simultaneously reproduce all three crucial features. We suggest that a combination of several dynamical feedbacks underestimated in the models at present, such as those related to ocean mixing and cloud albedo, may have been responsible for these climate conditions

An intercomparison between the GSWM, UARS, and ground based radar observations: a case-study in January 1993

The Global-Scale Wave Model (GSWM) is a steady-state two-dimensional linearized model capable of simulating the solar tides and planetary waves. In an effort to understand the capabilities and limitations of the GSWM throughout the upper mesosphere and thermosphere a comparative analysis with observational data is presented. A majority of the observational data used in this study was collected during the World Day campaign which ran from 20 January to 30 January 1993. During this campaign data from 18 ground-based observational sites across the globe and two instruments located on the UARS spacecraft were analyzed. Comparisons of these data with the simulations from the GSWM indicate that the GSWM results are in reasonable agreement with the observations. However, there are a number of cases where the agreement is not particularly good. One such instance is for the semidiurnal tide in the northern hemisphere, where the GSWM estimates may exceed observations by 50%. Through a number of numerical simulations, it appears that this discrepancy may be due to the eddy diffusivity profiles used by the GSWM. Other differences relating to the diurnal tide and the quasi-two-day wave are presented and discussed. Additionally, a discussion on the biases and aliasing difficulties which may arise in the observational data is alos presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47859/1/585_1997_Article_70151123.pd