Observations of oscillations of temperature and wind in planetary atmospheres provide a means of generalizing models for atmospheric dynamics in a diverse set of planets in the Solar System and elsewhere. An equatorial oscillation similar to one in the Earth's atmosphere has been discovered in Jupiter. Here we report the existence of similar oscillations in Saturn's atmosphere, from an analysis of over two decades of spatially resolved observations of its 7.8-mum methane and 12.2-mum ethane stratospheric emissions, where we compare zonal-mean stratospheric brightness temperatures at planetographic latitudes of 3.6 degrees and 15.5 degrees in both the northern and the southern hemispheres. These results support the interpretation of vertical and meridional variability of temperatures in Saturn's stratosphere as a manifestation of a wave phenomenon similar to that on the Earth and in Jupiter. The period of this oscillation is 14.8 +/- 1.2 terrestrial years, roughly half of Saturn's year, suggesting the influence of seasonal forcing, as is the case with the Earth's semi-annual oscillation.

When considering the probabilistic approach to neural networks in the framework of statistical pattern recognition we assume approximation of class-conditional probability distributions by finite mixtures of product components. The mixture components can be interpreted as probabilistic neurons in neurophysiological terms and, in this respect, the fixed probabilistic description contradicts the well known short-term dynamic properties of biological neurons. By introducing iterative schemes of recognition we show that some parameters of probabilistic neural networks can be "released" for the sake of dynamic processes without disturbing the statistically correct decision making. In particular, we can iteratively adapt the mixture component weights or modify the input pattern in order to facilitate correct recognition. Both procedures are shown to converge monotonically as a special case of the well known EM algorithm for estimating mixtures.

The atmospheres of the gas giant planets (Jupiter and Saturn) contain jets that dominate the circulation at visible levels. The power source for these jets (solar radiation, internal heat, or both) and their vertical structure below the upper cloud are major open questions in the atmospheric circulation and meteorology of giant planets. Several observations and in situ measurements found intense winds at a depth of 24 bar, and have been interpreted as supporting an internal heat source. This issue remains controversial, in part because of effects from the local meteorology. Here we report observations and modelling of two plumes in Jupiter's atmosphere that erupted at the same latitude as the strongest jet (23 degrees N). The plumes reached a height of 30 km above the surrounding clouds, moved faster than any other feature (169 m s(-1)), and left in their wake a turbulent planetary-scale disturbance containing red aerosols. On the basis of dynamical modelling, we conclude that the data are consistent only with a wind that extends well below the level where solar radiation is deposited.

Although lightning has been seen on other planets, including Jupiter, polar lightning has been known only on Earth. Optical observations from the New Horizons spacecraft have identified lightning at high latitudes above Jupiter up to 80 degrees N and 74 degrees S. Lightning rates and optical powers were similar at each pole, and the mean optical flux is comparable to that at nonpolar latitudes, which is consistent with the notion that internal heat is the main driver of convection. Both near-infrared and ground-based 5-micrometer thermal imagery reveal that cloud cover has thinned substantially since the 2000 Cassini flyby, particularly in the turbulent wake of the Great Red Spot and in the southern half of the equatorial region, demonstrating that vertical dynamical processes are time-varying on seasonal scales at mid- and low latitudes on Jupiter.

Studies have shown the chemopreventive effects of alpha-santalol on chemically and UVB-induced skin cancer in mice. The objective of the present investigation was to find the lowest effective concentration of alpha-santalol for the chemopreventive effects on UVB-induced skin tumor development in mice and to determine antiperoxidant effect of alpha-santalol in order to elucidate its possible mechanism of action. Female SKH-1 mice were divided into different groups receiving either vehicle alone or different concentrations of alpha-santalol. Mice in all the groups were initiated and promoted with UVB radiation for skin tumor development. The promotion phase continued for 30 weeks. Skin tumors were counted once a week for 30 weeks. Lipid peroxidation was assayed in skin and liver microsomes by measuring malonaldehyde formed using thiobarbituric acid method. Topical administration of alpha-santalol reduced UVB-induced skin tumor development in a concentration-dependent manner. Application of alpha-santalol (5%) significantly (p < 0.05) delayed skin tumor development for 25 weeks and reduced tumor multiplicity. alpha-Santalol also inhibited in vitro lipid peroxidation in skin and liver microsomes. alpha-Santalol application prevents UVB-induced skin tumor development possibly by acting as an antiperoxidant.

Previous studies from this laboratory have indicated that alpha-santalol (5%) provides chemopreventive effects in 7,12-dimethylbenz[a]anthracene (DMBA)-initiated and 12-O-tetradecanoylphorbol-13-acetate (TPA)-promoted skin cancer in CD-1 and SENCAR mice. Skin cancer development is associated with increased ornithine decarboxylase (ODC) activity, DNA synthesis and rapid proliferation of epidermal cells. The purpose of this investigation was to determine the effects of various concentrations (1.25% and 2.5%) of alpha-santalol on DMBA-initiated and TPA-promoted skin cancer development, TPA-induced ODC activity, and DNA synthesis in CD-1 mice. alpha-Santalol treatment at both concentrations (1.25% and 2.5%) prevented the skin cancer development. alpha-Santalol treatment (1.25% and 2.5%) resulted in a significant decrease in the TPA-induced ODC activity and incorporation of [3H]thymidine in DNA in the epidermis of CD-1 mice. There was no significant difference in the effects of 1.25% and 2.5% alpha-santalol on tumour incidence, multiplicity, epidermal TPA-induced ODC activity, or DNA synthesis in CD-1 mice.

Pomegranate seed oil was investigated for possible skin cancer chemopreventive efficacy in mice. In the main experiment, two groups consisting each of 30, 4-5-week-old, female CD(1) mice were used. Both groups had skin cancer initiated with an initial topical exposure of 7,12-dimethylbenzanthracene and with biweekly promotion using 12-O-tetradecanoylphorbol 13-acetate (TPA). The experimental group was pretreated with 5% pomegranate seed oil prior to each TPA application. Tumor incidence, the number of mice containing at least one tumor, was 100% and 93%, and multiplicity, the average number of tumors per mouse, was 20.8 and 16.3 per mouse after 20 weeks of promotion in the control and pomegranate seed oil-treated groups, respectively (P <.05). In a second experiment, two groups each consisting of three CD(1) mice were used to assess the effect of pomegranate seed oil on TPA-stimulated ornithine decarboxylase (ODC) activity, an important event in skin cancer promotion. Each group received a single topical application of TPA, with the experimental group receiving a topical treatment 1 h prior with 5% pomegranate seed oil. The mice were killed 5 h later, and ODC activity was assessed by radiometric method. The experimental group showed a 17% reduction in ODC activity. Pomegrante seed oil (5%) significantly decreased (P <.05) tumor incidence, multiplicity, and TPA-induced ODC activity. Overall, the results highlight the potential of pomegranate seed oil as a safe and effective chemopreventive agent against skin cancer.