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In forests, a significant proportion of the carbon fixed by trees during photosynthesis is transported belowground along the conducting phloem, so variations in phloem anatomy can lead to variations in transport capacity. Phloem conductance at tree level (Ktree) is also affected by tree height. Both the phloem anatomy and the tree size change during ontogeny, and also differ under different environmental conditions. The goal of our work was to identify the main drivers of variation in Ktree in Scots pine trees growing in natural boreal forests. We conducted a phloem anatomical study and calculated Ktree in trees of three age groups growing in different climatic conditions along a latitudinal gradient from south to north. We found that Ktree was maintained at the same level in actively growing pine trees (25–80-years-old) but increased in old-aged trees (180–190-years-old), possibly reflecting the shift in source-sink relationships of aboveground and belowground parts of trees. Trees of the same age group growing in different climatic conditions demonstrated similar values of Ktree due to coordinated changes in the phloem anatomy and the tree height. In general, the negative influence of tree height on Ktree is offset by the positive influence of phloem width (or trunk diameter) and sieve cell diameter. The exception was young trees growing in the transition zone of the northern taiga subzone to the tundra, where Ktree was the highest in its age group and even exceeded Ktree of middle-aged trees. [ABSTRACT FROM AUTHOR]

The Earth close approach of near-Earth asteroid 2005 LW3 on 2022 November 23 represented a good opportunity for a second observing campaign to test the timing accuracy of astrometric observation. With 82 participating stations, the International Asteroid Warning Network collected 1046 observations of 2005 LW3 around the time of the close approach. Compared to the previous timing campaign targeting 2019 XS, some individual observers were able to significantly improve the accuracy of their reported observation times. In particular, U.S. surveys achieved good timing performance. However, no broad, systematic improvement was achieved compared to the previous campaign, with an overall negative bias persisting among the different observers. The calibration of observing times and the mitigation of timing errors should be important future considerations for observers and orbit computers, respectively.

Experimental studies of vibrations of asynchronous electric motors (EMs) of the electric bus traction electric drive arecarried out in the paper. The presented studies are based on generalization of the diagnostic features of vibrationcharacteristics and statistics concerning the limiting values of vibration parameters of EMs and their dependence on thetechnical condition. The analysis of the obtained results allowed us to determine the permissible vibration levels of EMs inthe frequency range from 5 Hz to 10 kHz. The method of diagnosing EMs traction electric drive according to theindicators of vibration levels is developed, which allows to evaluate their technical condition. The values of thepermissible vibrational accelerations of the electric bus EMs are determined, which enable to estimate their technical level.This method allowed to develop classes of evaluation of the EMs technical condition by the level of their vibration, whichmakes possible to predict their resource.

In the review it is come up with information on the possibilities of breeding programs and the creation of seed orhards of Scots pine (Pinus sylvestris L) as one of the key species of forests in Eurasia, which has significant economic value. Somatic embryogenesis is a promising biotechnological method that allows mass propagation of valuable individuals obtained, including during the implementation of breeding programs. Using the example of various species of the Pinus genus, the main stages of somatic embryogenesis are described. The influence of the conditions and period of cultivation on the effectiveness of somatic embryogenesis and the subsequent conversion of somatic embryos into the plants are considered. Particular attention is paid to the growth and physiology of clones in the field.

The effect of site preparation (mixed mounding and removal of the humus layer) under a shelterwood of mixed boreal forest along a forest interior-edge gradient on Norway spruce (Picea abies) seedlings was studied two years after planting. Mounds had a positive effect on root development, ectomycorrhiza formation and the absorption of nitrogen (N) and phosphorus (P) in the seedlings, and augmented their survival, growth and biomass. Humus removal had an adverse effect on the root biomass and ectomycorrhiza formation. A decreased soil fertility after the removal of humus led to a low N and P content in the seedlings. Two years after planting, humus removal had not affected the growth of the seedlings, but reduced their biomass. The influence of the forest edge, compared to the interior plot, was mostly associated with a decrease in the stand density, reduced amount of litter and increased light availability for the seedlings. [ABSTRACT FROM AUTHOR]

Experimental studies of vibrations of asynchronous electric motors (EMs) of the electric bus traction electric drive are carried out in the paper. The presented studies are based on generalization of the diagnostic features of vibration characteristics and statistics concerning the limiting values of vibration parameters of EMs and their dependence on the technical condition. The analysis of the obtained results allowed us to determine the permissible vibration levels of EMs in the frequency range from 5 Hz to 10 kHz. The method of diagnosing EMs traction electric drive according to the indicators of vibration levels is developed, which allows to evaluate their technical condition. The values of the permissible vibrational accelerations of the electric bus EMs are determined, which enable to estimate their technical level. This method allowed to develop classes of evaluation of the EMs technical condition by the level of their vibration, which makes possible to predict their resource. [ABSTRACT FROM AUTHOR]

In the present paper, the results of the research of biometric parameters and functional peculiarities of photosynthetic apparatus of Stellaria humifusa in West Spitsbergen are discussed. The study showed that the largest proportion of the mat is composed of a brown layer of dead leaves covering the assimilative organs (about 70%). Green leaves and shoots accounted for about 20%, whereas generative organs - for about 10% of the mat mass. The values of the maximum photochemical quantum yield of PS II (FV/FM) in all the studied plants were lower than the optimal values (0.83), which suggests that the plants are exposed to stress factors. The low values of chlorophyll and carotenoid content and relatively high values of the light-harvesting complex (70-80%), the sharp decrease in the quantum yield of PS II (ΦPSII) entailed by a marginal increase in PPFD indicative of a sufficiently high of photochemical activity within the range of low and medium values of light. It also suggests that Stellaria humifusa is well-adapted to the shaded conditions created in the mat. Besides, a considerable decrease the maximum fluorescence yield of a light-adapted leaf (FM') at increasing PPFD was observed, which suggests that Stellaria humifusa has a well-developed mechanism of energy dissipation via the non-photochemical (NPQ) pathway. The rapid development of NPQ gives reason to assume that, under high light conditions, non-photochemical quenching is likely to serve as the main mechanism for preventing the photodamage of the photosynthetic apparatus. Thus, it was shown that the photosynthetic apparatus of Stellaria humifusa works efficiently under the conditions created in the mat, and the thick layer of dead leaves covering the assimilative organs, on the one hand, protects them from excessive light, and on the other hand, absorbs thermal energy, which raises temperature of the local habitat. [ABSTRACT FROM AUTHOR]

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We report observations of colour in the inner coma of Comet C/2013 UQ4 (Catalina) with the broad-band B and R filters. We find significant temporal variations of the colour slope, ranging from -12.67 ± 8.16% per 0.1 µm to 35.09 ± 11.70% per 0.1 µm. It is significant that the comet changes colour from red to blue over a period of only 2 d. Such dispersion cannot be characterized with an average colour slope. We also observe Comet C/2013 UQ4 (Catalina) in infrared using Spitzer and find no significant CO/CO2 gaseous species in its coma. Therefore, we classify Comet C/2013 UQ4 (Catalina) as a dust-rich comet and attribute the measured colour slope to its dust. We analyse the colour slope using the model of agglomerated debris particles and conclude that the C/2013 UQ4 coma was chemically heterogeneous, consisting of at least two components. The first component producing the bluest colour is consistent with Mg-rich silicates. There are three different options for the second component producing the reddest colour. This colour is consistent with either Mg-Fe silicates, kerogen type II or organic matter processed with a low dose of ultraviolet radiation. [ABSTRACT FROM AUTHOR]