Further studies on meiosis and pollen formation in Larix

The meiotic development in pollen mother cells of Larix decidua, L. leptolepis and L. sibirica growing at different localities In Sweden was studied. The percentage of completely damaged buds as well as the pollen sterility was estimated. The reaching of diplotene took place earlier in L, sibirica than in L. decidua and L. leptolepis. The second phase of high frost sensitivity (diakinesis - telophase II, except for the interphase) in the PMC appeared in the sequence L. sibirica - L. leptolepis - L, decidua. Differences within a species from locality to locality regarding the initiation of further development from diplotene could be attributed to differences in temperature conditions at the different growth localities. The same was true for the induction of completely damaged bud

Flowering in a clone trial of Picea abies Karst

The female and male flowering frequency were studied in a clone trial of Picea abies at Röskär nine kilometers north-east of Stockholm. During 1971 the extension in time of pollen shedding and female receptivity was recorded following daily examination of individual strobili. The data obtained revealed a great variation in female as well as male flowering between the clones. Only a part of this variation could be attributed to differences in height of the clones. Great yearly variations in flowering of individual grafts were noticed. Based on the flowering frequency as well as the pollen shedding and female receptivity during each day, the expected contribution of the different clones to the offspring was calculated. According to the calculations four of the clones contributed 55 per cent of the genes to the offspring. Many (66) of the 190 theoretically possible combinations among the 20 clones occurred in a lower frequency than 0.1 per cent. The consequences of the data obtained for the genetic composition of the seed orchard progeny were discussed

Flowering in a seed orchard of Pinus silvestris L.

Flowering phenology and flowering frequencies were investigated in clones of Swedish and Finnish origin growing in a pine seed orchard at Långtora (lat 59°43´, long. 17°08`, alt. 15 m). One purpose was to estimate the gene contribution of individual clones to the progeny. The frequencies of female and male strobili were estimated in 1973-1975. The onset and duration of both female receptivity and pollen dispersal were recorded. The pollen density in the seed orchard was estimated. Great clonal variation prevailed in the seed orchard with respect to the frequency of female and male flowering as well as the onset and duration of female receptivity and pollen dispersal. A good agreement in flowering frequencies and phenological characteristics of the clones between different years was observed. The great vaiation in onset and duration of receptivity and pollen dispersal from year to year was influenced to a great extent by the prevailing temperature conditions in the spring, different years. The calculations of the genetic composition of the progeny revealed that the gene contribution of the analysed clones varied considerably. This was mainly due to differences in the frequency of flowering

Studies on frost hardiness of Pinus contorta Dougl. seedlings grown in climate chambers

Pinus contorta populations from latitudes 47o to 63'N were cultivated in climate chambers and freeze tested at varying photoperiods. The results were compared with data from field trials comprising other populations from the same latitudinal range. A good agreement between our data on frost hardiness from the climate chambers and the ones front field trials was obtained. Breeding for frost hardiness in Pinus contorta ought to be done by early testing using the design developed in the present investigation. The longer the night length the greater the hardiness. Low temperature during the night promotes the development of hardiness. The more northern the origin the shorter the night length required to induce hardiness. Dry matter content of the upper 3 cm of the shoots and the lengthening of the secondary needles are strongly correlated with hardiness

6-Hydroxydopamine induced degeneration of noradrenaline neurons in the scorbutic guinea-pig

The effect of the neurotoxic compound 6-hydroxydopamine and its immediate precursor 6-hydroxy-DOPA on noradrenaline uptake and storage in central and peripheral catecholamine neurons of scorbutic and normal guinea-pigs has been investigated. Endogenous noradrenaline in heart and brain as well as the in vitro uptake-accumulation of 3H-noradrenaline in iris and slices of heart and brain were not significantly changed in scorbutic animals. The in vitro formation of 3H-noradrenaline from 3H-dopamine was markedly reduced in heart slices of scorbutic guinea-pigs, due to ascorbic acid being a co-factor for dopamine-β-hydroxylase. There was an increased depletion of brain noradrenaline following tyrosine hydroxylase inhibition produced by α-methyl-p-tyrosine methylester in scorbutic animals, indicating an increased NA turnover. Administration of 6-hydroxydopamine or 6-hydroxy-DOPA resulted in a similar reduction of endogenous NA in brain and heart as well as of the in vitro uptake of 3H-noradrenaline in iris, and slices from heart, cerebral cortex and hypothalamus in scorbutic and control guinea-pigs. These results are discussed in view of current hypotheses on mechanisms involved in the neurotoxic action of 6-hydroxydopamine on catecholamine neurons

ISSN 1400‐3902Exploratory Learning Structure in Artificial Cognitive Systems ⋆

Abstract. One major goal of the COSPAL project is to develop an artificial cognitive system architecture with the capability of exploratory learning. Exploratory learning is a strategy that allows to apply generalization on a conceptual level, resulting in an extension of competences. Whereas classical learning methods aim at best possible generalization, i.e., concluding from a number of samples of a problem class to the problem class itself, exploration aims at applying acquired competences to a new problem class. Incremental or online learning is an inherent requirement to perform exploratory learning. Exploratory learning requires new theoretic tools and new algorithms. In the COSPAL project, we mainly investigate reinforcement-type learning methods for exploratory learning and in this paper we focus on its algorithmic aspect. Learning is performed in terms of four nested loops, where the outermost loop reflects the user-reinforcement-feedback loop, the intermediate two loops switch between different solution modes at symbolic respectively sub-symbolic level, and the innermost loop performs the acquired competences in terms of perception-action cycles. We present a system diagram which explains this process in more detail

Exploratory Learning Structure in Artificial Cognitive Systems

One major goal of the COSPAL project is to develop an artificial cognitive system architecture with the capability of exploratory learning. Exploratory learning is a strategy that allows to apply generalization on a conceptual level, resulting in an extension of competences. Whereas classical learning methods aim at best possible generalization, i.e., concluding from a number of samples of a problem class to the problem class itself, exploration aims at applying acquired competences to a new problem class. Incremental or online learning is an inherent requirement to perform exploratory learning. Exploratory learning requires new theoretic tools and new algorithms. In the COSPAL project, we mainly investigate reinforcement-type learning methods for exploratory learning and in this paper we focus on its algorithmic aspect. Learning is performed in terms of four nested loops, where the outermost loop reflects the user-reinforcement-feedback loop, the intermediate two loops switch between different solution modes at symbolic respectively sub-symbolic level, and the innermost loop performs the acquired competences in terms of perception-action cycles. We present a system diagram which explains this process in more detail. We discuss the learning strategy in terms of learning scenarios provided by the user. This interaction between user (’teacher’) and system is a major difference to most existing systems where the system designer places his world model into the system. We believe that this is the key to extendable robust system behavior and successful interaction of humans and artificial cognitive systems. We furthermore address the issue of bootstrapping the system, and, in particular, the visual recognition module.We give some more in-depth details about our recognition method and how feedback from higher levels is implemented. The described system is however work in progress and no final results are available yet. The available preliminary results that we have achieved so far, clearly point towards a successful proof of the architecture concept

Exploratory learning structure in artificial cognitive systems

Abstract. One major goal of the COSPAL project is to develop an artificial cognitive system architecture with the capability of exploratory learning. Exploratory learning is a strategy that allows to apply generalization on a conceptual level, resulting in an extension of competences. Whereas classical learning methods aim at best possible generalization, i.e., concluding from a number of samples of a problem class to the problem class itself, exploration aims at applying acquired competences to a new problem class. Incremental or online learning is an inherent requirement to perform exploratory learning. Exploratory learning requires new theoretic tools and new algorithms. In the COSPAL project, we mainly investigate reinforcement-type learning methods for exploratory learning and in this paper we focus on its algorithmic aspect. Learning is performed in terms of four nested loops, where the outermost loop reflects the user-reinforcement-feedback loop, the intermediate two loops switch between different solution modes at symbolic respectively sub-symbolic level, and the innermost loop performs the acquired competences in terms of perception-action cycles. We present a system diagram which explains this process in more detail. We discuss the learning strategy in terms of learning scenarios provided by the user. This interaction between user (’teacher’) and system is a major difference to most existing systems where the system designer places his world model into the system. We believe that this is the key to extendable robust system behavior and successful interaction of humans and artificial cognitive systems. We furthermore address the issue of bootstrapping the system, and, in particular, the visual recognition module. We give some more in-depth details about our recognition method and how feedback from higher levels is implemented. The described system is however work in progress and no final results are available yet. The available preliminary results that we have achieved so far, clearly point towards a successful proof of the architecture concept.