Reproductive ecology ot the boreal riparian guild of Draophtla -Ecography 16 65-72The reproductive ecology of four sympatric Drosophila virths group species (Diptcra Drosophilidae) was studied in the field to trace the factors maintaining species isolation There was a high probability of meeting a heterospecific individual belonging to the same species group on the basis of adult spatial occurrence Direct field observations revealed that the males court also females of the foreign species but interspecific courtships do not lead to mating The main mating period among these species lasted only several weeks and the timing of mating periods differed markcdlv in the three most common species Reproductive character displacement between species may explain the observed differences m the liming of the mating periods but they could have arisen in the context of other selective pressures than the prevention of interspecific courtships and matings
In Finland, forest management planning is based on standwise assessment of forest variables. The data is traditionally gathered partly by (subjective) sampling and partly by visual assessment, which makes the accuracy assessments difficult. This study consists of an experiment where the visual assessments of field technicians were compared with the accurately measured values. The data consists of assessments from 18 sample plots made by 19 technicians. Each technician assessed four forest characteristics from each stand, for each tree species and each tree class. Basal area was observed in all cases; the other three variables varied according to 18 different measurement strategies. From these observations, mixed models were estimated to analyze to what extent the assessment errors depend on forest characteristics. Variation among both sample plots and field technicians was also considered. The results show that some of the variables could be interpreted as Berkson cases. The assessment errors were also often highly hetero sce dastic. Therefore, variance was explicitly modeled, and the final error models were estimated with weighted mixed regression using the variance estimates as weights. The results show clear variation among technicians, especially in characteristics that include personal judgment. The effect of training could be detected from variation between the technician groups. Furthermore, the broad-leaved tree classes were generally more difficult to assess than conifers.
We use recently digitized sunspot drawings from Mount Wilson Observatory to investigate the latitudinal dependence of tilt angles of active regions and its change with solar cycle. The drawings cover the period from 1917 to present and contain information about polarity and strength of magnetic field in sunspots. We identify clusters of sunspots of same polarity, and used these clusters to form "bipole pairs". The orientation of these bipole pairs was used to measure their tilts. We find that the latitudinal profile of tilts does not monotonically increase with latitude as most previous studies assumed, but instead, it shows a clear maximum at about 25-30 degree latitudes. Functional dependence of tilt (γ) on latitude (ϕ) was found to be γ = (0.20 ± 0.08) sin(2.80ϕ) + (−0.00 ± 0.06). We also find that latitudinal dependence of tilts varies from one solar cycle to another, but larger tilts do not seem to result in stronger solar cycles. Finally, we find the presence of a systematic offset in tilt of active regions (non-zero tilts at the equator), with odd cycles exhibiting negative offset and even cycles showing the positive offset.
Context. Systematic observations of magnetic field strength and polarity in sunspots began at Mount Wilson Observatory (MWO), USA in early 1917. Except for a few brief interruptions, this historical dataset has continued until the present. Aims. Sunspot field strength and polarity observations are critical in our project of reconstructing the solar magnetic field over the last hundred years. We provide a detailed description of the newly digitized dataset of drawings of sunspot magnetic field observations. Methods. The digitization of MWO drawings is based on a software package that we developed. It includes a semiautomatic selection of solar limbs and other features of the drawing, and a manual entry of the time of observations, measured field strength, and other notes handwritten on each drawing. The data are preserved in an MySQL database. Results. We provide a brief history of the project and describe the results from digitizing this historical dataset. We also provide a summary of the final dataset and describe its known limitations. Finally, we compare the sunspot magnetic field measurements with those from other instruments, and demonstrate that, if needed, the dataset could be continued using modern observations such as, for example, the Vector Stokes Magnetograph on the Synoptic Optical Long-term Investigations of the Sun platform.
Objective: To resolve how the preferred chewing side (PCS) affects facial asymmetry in twins, whether there are differences between monozygotic (MZ) and dizygotic (DZ) twins, and whether the twins with PCS have more asymmetric faces compared to symmetrically chewing twins. Material and methods: The study included 106 Lithuanian twin pairs of the same sex, 59 MZ and 47 DZ pairs. The data were analysed from facial 3D images and manually added landmarks. 3D images were analysed by Rapidform2006 software and statistical analyses were done by using the R software environment version 4.1.0. Results: The contralateral effect of PCS and larger chin side was dominant among right and non-right side chewing twins. Being female increased the whole face symmetry. Conclusion:The volume of the chin becomes larger on the side opposite to the twins' habitual chewing side. As the results are quite similar in both twin types, functional factors are more prominent than heredity.
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