71 research outputs found

    Learning and Educational Programs for Entrepreneurs

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    This chapter summarizes the latest studies in entrepreneurial learning in order to highlight their implications for the design of educational programs (Pittaway & Thorpe, 2012). It examines in detail the latest thinking on the subject, summarizes the key concepts and empirical contributions with a particular focus on expanding understanding of ‘situated’, social and contextual learning (Lave & Wenger, 1991). The chapter stems from Pittaway and Thorpe’s (2012: 850) summary of Cope’s framework. Here it highlights critical concepts, such as dynamic temporal phases, forms and characteristics of learning (Cope, 2010) and lays out the underlying principles of each concept. Following this initial framework recent contributions to the subject of entrepreneurial learning, both conceptual and empirical, are presented to provide an up-to-date picture of thinking in the field. The latter part of the chapter highlights implications of current thinking on the design of development programs for entrepreneurs. It focuses on how concepts in this field can be used to enhance efforts to consider, design and deliver educational programs for entrepreneurs. A number of forms of educational practice are recommended based on this analysis. The chapter closes by considering future developments and lines of inquiry in entrepreneurial learnin

    Mapping functional regions of the segment-specific transcription factor Krox-20.

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    Krox-20, a zinc finger transcription factor with similarity to Sp1, is likely to play an important role in the development of the vertebrate central nervous system. A knowledge of its molecular properties will help to understand its physiological functions. We have therefore performed a structure-function analysis of the protein to identify the regions involved in DNA-binding and transcriptional activation. Our data suggest that only the zinc fingers are required for high affinity, specific DNA-binding. Transcriptional activation was not affected by deletion of the C-terminal tail of the protein. In contrast, deletion of the N-terminal half, upstream of the zinc fingers, completely abolished transactivation without affecting DNA-binding or nuclear localization. Two transcriptional activation domains were identified in this region. They cooperate to establish full activity. They are rich in negatively-charged amino acids and are therefore may constitute acidic activation domains. Comparative analysis of the amino acid sequences of several zinc finger proteins belonging to the Krox-20 subfamily indicates that they contain acidic regions at similar locations within their N-terminal region, suggesting that the functional organization of these proteins has been conserved during evolution

    Calcium-magnesium exchange on Wyoming bentonite in the presence of adsorbed sodium

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    The exchange of magnesium for calcium at 298 K on Wyoming bentonite was investigated in a SO mol m~3 perchlorate background maintained at pH 7. The charge fraction of Na+ in the aqueous solution phase was controlled at the values of 0.74 or 0.87 during the exchange experiments, resulting in average exchangeable sodium percentages (ESP) of either 16 or 36% on the clay. The Vanselow selectivity coefficient for Ca —• Mg exchange was equal to 1.0 and was independent of exchanger composition at both ESP values. This result implied that, under the conditions of the exchange experiments, the clay exhibited equal affinities for Ca2* and Mg2+ regardless of the quantity of adsorbed sodium present

    Family of Ebf/Olf-1-related genes potentially involved in neuronal differentiation and regional specification in the central nervous system

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    International audienceTwo novel mouse genes, Ebf2 and Ebf3, have been identified which show high similarity to the rodent Ebf/Olf-1 and the Drosophila collier genes. The strong conservation of the protein regions corresponding to the DNA binding and dimerisation domains previously defined in Ebf strongly suggests that Ebf2 and Ebf3 also constitute DNA sequence-specific transcription factors. Determination of the chromosomal locations of the two genes indicated that the different members of this novel mouse multigene family are not clustered. A detailed analysis of the expression of each of the three Ebf genes in the developing central nervous system revealed partially overlapping patterns with two salient features: 1) In the region extending from the midbrain to the spinal cord, the expression of the three genes correlated with neuronal maturation, with a general activation in early post-mitotic cells, followed by specific patterns of extinction also consistent with the neurogenic gradient. 2) In the forebrain area, although the patterns of expression of the Ebf genes also reflected neuronal maturation, they appeared in addition to be region specific. These data suggest that Ebf genes may be involved in the control of neuronal differentiation in the CNS and in enforcing regional diversity in populations of post-mitotic forebrain neurons

    The segment-specific gene Krox-20 encodes a transcription factor with binding sites in the promoter region of the Hox-1.4 gene

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    Krox-20 is a mouse zinc finger gene expressed in a segment-specific manner in the early central nervous system, which makes it a potential developmental control gene. In this report, we show that the Krox-20 protein binds in vitro to two specific DNA sites located upstream from the homeobox containing gene Hox-1.4. The nucleotide sequence recognized by Krox-20 is closely related to the Sp1 target sequence, which is consistent with the similarity existing between the zinc fingers of the two proteins. In co-transfection experiments in cultured cells, Krox-20 dramatically activates transcription from the herpes simplex virus thymidine kinase promoter when an oligomer of its binding site is present in cis close to the promoter. Analysis of mutated binding sites demonstrates that the level of activation by Krox-20 correlates with the affinity of the protein for the mutant sequence. These data indicate that Krox-20 constitutes a sequence-specific DNA-binding transcription factor. Parallel analysis of the expression of Krox-20 and Hox-1.4 in the neural tube by in situ hybridization revealed no overlap, arguing against direct interactions between these two genes. The possible involvement of Krox-20 in the regulation of the transcription of other homeobox genes is discussed in view of their respective patterns of expression
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