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1.
MAARTEN T.BASTIAENS RUDI G.J. WESTENDORP BERT J. VERMEER JAN N. BOUWES BAVINCK 《Pigment cell & melanoma research》1999,12(5):316-322
Ephelides and solar lentigines are benign pigmented spots, which are currently associated with an increased risk of skin cancer. These two pigmented spots are known to be discriminated by their clinical, histological, and electron microscopic characteristics, even though occasional misclassification can occur because of their similarity. It has also been questioned whether these spots are not one and the same. In this study, we have attempted to differentiate between these two pigmented spots with the use of a standardized protocol for clinical examinations on 272 healthy volunteers, paying particular consideration to their pigmentary and constitutional host factors. We found that solar lentigines 1) are more prevalent than ephelides, 2) increase in prevalence and number with higher age, and 3) are most prevalent on the trunk and occur more frequently in males than in females. A trend is also observed whereby ephelides 1) loose their prevalence with age, 2) become equally distributed on the face, arms, and trunk, and 3) occur more frequently in females. An intimate association of ephelides, but not solar lentigines, has been found with hair color and skin type. All of these findings are in agreement with most of those reported in the literature, supporting the view that ephelides and solar lentigines are different types of pigmented lesions. 相似文献
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In the Chihuahuan Desert of the southwestern United States we monitored responses of both winter and summer annual plant communities to natural environmental variation and to experimental removal of seed-eating rodents and ants for 13 years. Analyses of data on population densities of the species by principal component analysis (PCA) followed by repeated measures analysis of variance (rmANOVA) on PCA scores showed that: (1) composition of both winter and summer annual communities varied substantially from year to year, presumably in response to interannual climatic variation, and (2) community composition of winter annuals was also significantly affected by the experimental manipulations of seed-eating animals, but the composition of the summer annual community showed no significant response to these experimental treatments. Canonical discriminant analysis (CDA) was then applied to the data for winter annuals to more clearly identify the responses to the different classes of experimental manipulations. This analysis showed that removing rodents or ants or both taxa caused distinctive changes in species composition. There was a tendency for large-seeded species to increase on rodent removal plots and to decrease on ant removal plots, and for small-seeded species to change in the opposite direction. In the winter annual community there was a significant time x treatment interaction: certain combinations of species that responded differently to removal of granivores also showed opposite fluctuations in response to long-term climatic variation. The large year-to-year variation in the summer annual community was closely and positively correlated across all experimental treatments. The use of multivariate analysis in conjunction with long-term monitoring and experimental manipulation shows how biotic interactions interact with variation in abiotic conditions to affect community dynamics. 相似文献
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E. Gacia H. Kennedy J. Terrados S. Papadimitriou 《Journal of experimental marine biology and ecology》2005,316(1):55-67
Seagrass meadows are important primary producers in SE-Asia coastal areas that are increasingly threatened by human activities resulting in a deterioration of the underwater light environment. The resilience of seagrass meadows to decreasing light availability should be approached in an integrative manner, because they shelter complex communities of primary and secondary producers. The aim of this study was to measure the in situ metabolism of a seagrass community under different levels of light availability following changes in the water column dissolved oxygen (DO) and dissolved inorganic carbon (DIC), the sediment redox potential and seagrass production. Net community production (NCP) and respiration were measured along two diel cycles to produce a balance of NCP under different light treatments. On a daily basis, at full irradiance, the community metabolism presented a net production which was close to zero, with values of −7.75 to 16.6 mmol O2 m−2 day−1 for DO, and −56.8 to 22.7 mmol C m−2 day−1 for DIC in the first and second incubation runs, respectively. Compensation irradiance for the NCP was thus found to be close to 80% of the present light availability. Shading resulted in a general decrease in the sediment redox potential, while the initial redox potential had not recovered 6 days after exposure to full sunlight. This community appears to be in a fragile equilibrium with the environment, and any minor decrease in the water transparency would lead to a shift from an autotrophic to a heterotrophic system. 相似文献
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I. N. Konareva 《Neurophysiology》2006,38(3):201-208
Modifications of different EEG rhythms induced by a single neurofeedback session (by the EEG characteristics) directed toward
an increase in the ratio of the spectral powers (SPs) of the α vs θ oscillations were compared with the psychological characteristics of the tested subjects (the group included 30 persons).
A generally accepted neurofeedback technique was used; the intensity of acoustic white noise served as the feedback signal.
EEG potentials were recorded from the C3 and C4 leads. Psychological testing was carried out using Eysenck’s (EPQ), Rusalov’s
(OST), and (16 PF) questionnaires. The directions of changes in the SPs of EEG frequency components were found to significantly
correlate with some individuality-related peculiarities of the tested subjects. The SP of the δ rhythm correlated with the
EPQ scale “neuroticism,” OST scale “social plasticity,” and 16 PF factors H (“parmia”), I (“premsia”), and Q3 (“self-control of behavior”). The SP of the θ component demonstrated correlations with the OST scales “ergisity,” “plasticity,”
and “social temp” and with 16 PF factors M (“autia”), Q4 (“frustration”), and Q1 (“exvia”). The SP of the α rhythm correlated with 16 PF factors Q3 (“self-control of behavior”), G (“strength of superEgo”), O (“hypothymia”), L (“protension”), and N (“shrewdness”). The SP
of the β rhythm correlated with the OST scale “emotionality,” while that of the γ rhythm showed correlations with the 16 PF
indices L (“protension”) and M (“autia”). Changes in the ratio of the α vs θ SPs correlated with the EPQ scale “neuroticism.” Thus, our data confirm the statement that a high individual variability
of the results of a single (first in the series) neurofeedback session is to a great extent related to peculiarities of the
individual psychological pattern of the subject.
Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 239–247, May–June, 2006. 相似文献
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Kristjan Zobel 《Evolutionary ecology》2008,22(3):487-492
Although sexuality is considered evolutionarily progressive, clonality is very common in plants and the prevailing means of
reproduction in several community types. I discuss what could be the forces that have influenced the selection among sexual
versus non-sexual reproduction at community level. I propose that, among others, the probability of self-competition must
have been one of the key factors. The probability of meeting one’s own genes for wasteful competition is higher in communities
where clonality prevails (and relatively high mean intra-species relatedness is expected), and higher in communities with
low species diversity. On the other hand, lower diversity indicates a higher average fitness of species since the (finite)
total pool of resources is distributed among fewer population with high density. I show, using four community types with contrasting
diversity and clonality that community fitness (average fitness in the assemblage of species) can be expressed as the product
of two variables––anti-diversity and degree of sexuality. 相似文献