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Nach der Schulzeit droht Lernbeeinträchtigten durch die allgemeine Entwicklung auf dem Arbeits- und Ausbildungsmarkt eine schwierige Berufsfindung, hochgradig unbefriedigende Hilfsarbeiter-Tätigkeit und - in erheblich zunehmendem Maße - Arbeitslosigkeit und der Verlust von Lebensperspektiven. Der Beitrag zeigt Möglichkeiten und Grenzen der qualifizierten und zukunfts orientierten Berufsausbildung dieser Gruppe auf, wobei sowohl moderne technologische Entwicklungen als auch die Förderung personaler und sozialer Kompetenzen Berücksichtigung finden. Die Fragestellung der Integration Lernbeeinträchtigter wird nicht mit der Schulzeit abgeschlossen - sie stellt sich umso stärker danach.
Werkstatt für Behinderte
(1994)
No abstract available
Verhaltensauffälligkeit
(1994)
No abstract available
MCD
(1994)
No abstract available
Lernen
(1994)
No abstract available
Lernbehinderung
(1994)
No abstract available
Ausbildung
(1994)
No abstract available
Assoziationen von Ameisen mit Pflanzen (und oft noch mit pflanzensaugenden Insekten als drittem Partner) dürften eine Ursache des Artenreichtums und der hohen Abundanzen tropischer Formicidae sein. Die von den Ameisen genutzten Pflanzen bieten entweder Nahrung an, über extraflorale Nektarien und/oder Nährkörperchen, oder aber - bei den eigentlichen Myrmekophyten - Nistraum und z.T. auch Nahrung. Diese Beziehungen zeichnen sich durch unterschiedliche Nutzungsweisen und Nutzungsintensitäten und damit stark differierende Abhängigkeit der Partner voneinander aus. Ein besonders breites Spektrum von Ameisen-Pflanzen-Assoziationen finden wir in der paläotropischen Baumgattung Macaranga (Euphorbiaceae), die sich daher als Modellsystem für vergleichende Untersuchungen hervorragend eignet. Die Grundfrage unserer Untersuchungen an diesem System lautet: Verläuft aufgrund der ausgeprägt mosaikartigen Verteilung der von den myrmekophilen Pflanzen angebotenen Nahrungs- und Nistraumressourcen die Neu- und Wiederbesiedlung von Habitaten durch die Ameisen in Form von Zufallsprozessen? Oder werden, im Gegenteil, durch diesen Umstand Spezialisierungen seitens der Ameisen gefördert und die Zusammensetzung der Lebensgemeinschaften dadurch stärker deterministisch geprägt? Unsere bisherigen Untersuchungen zeigen, daß beide Prinzipien wirken. Bei der alleinigen Nutzung von Nahrungsressourcen fehlen spezialisierte Beziehungen weitgehend und stochastische Ereignisse dürften sehr häufig die Pflanzen-Ameisen-Assoziation bestimmen. Bei den eigentlichen Myrmekophyten hingegen ist die Auswahl der assozierten Ameisen viel stärker determiniert, ganz besonders dann, wenn der Wohnraum, den die Pflanze offeriert, nur durch aktives Öffnen seitens der Ameisen erschlossen werden kann.
Homozygous deletions in Wilms' tumor DNA have been a key step in the identification and isolation of the WTI gene. Several additional loci are also postulated to contribute to Wilms' tumor formation. To assess the frequency of WTI alterations we have analyzed the WTI locus in a panel of 77 Wilms' tumors. Eight tumors showed evidence for large deletions of several hundred or thousand kilobasepairs of DNA, some of which were also cytogenetically detected. Additional intragenic mutations were detected using more sensitive SSCP analyses to scan all 10 WTI exons. Most of these result in premature stop codons or missense mutations that inactivate the remaining WTI allele. The overall frequency of WTI alterations detected with these methods is less than 15%. While some mutations may not be detectable with the methods employed, our results suggest that direct alterations of the WTI gene are present in only a small fraction of Wilms' tumors. Thus, mutations at other Wilms' tumor loci or disturbance of interactions between these genes likely play an important role in Wilms' tumor development.
No abstract available
The 2-halo imidoyl chlorides 7 are obtained from the amide 5 and the 2-halo amides 6 by the action of phosphorus pentachloride and thionyl chloride, respectively. Non-racemic (S)-6a is converted into 7a which is racemic, however. The reaction of Lawesson's reagent with 6a furnishes the diastereomeric 1,3.2-thiazaphospholidine derivatives 15. Treatment of (S)-6a (98% eel with methyl triflate affords 2-chloro imidate 8 (95% eel which reacts with methanamine in the presence of methanammonium chloride to yield the 2-chloro amidine (S)-9a (90% eel. The 2-halo imidoyl halides 7a and b react with methanamine to produce the 2-halo amidines 9a and b. - Strong bases, e.g. potassium tert-butoxide or sodium hydride in the presence of catalytic amounts of tertbutyl alcohol, eliminate hydrogen chloride or bromide from the 2-halo amidines 9a and band (S)-9a to yield mixtures of Recently, we demonstrated that the formation of the chiral non-racemic aziridinone (R)-2 from the a-chloro amide (5)-1 by base-promoted dehydrochlorination[2) as well as the nucleophilic cleavage of the N-C(3) bond of (R)_2[3,4) occur with inversion of configuration, thus excluding the intervention of achiral (acyclic) intermediates. In the temperature range of lOO-170°C, however, slow racemization accompanies the thermolysis of (R)-2 and indicates the existence of an achiral or a racemic transient, e. g. (M)-3 + (P)-3. Indeed, high-level quantum-chemical calculations reveal that an activation energy of (170 ± 25) kJmol- 1 is required for the unimolecular ring opening of the parent aziridinone which affords a species of high diradical character[41. Subsequently, the unstable N-phenylaziridinone invoked in the decomposition of the (5)-2-bromopropananilide anion was shown to react with tert-butylamine or dimethylformamide with inversion of configuration at C(3)[51. Thus, the stereochemical evidence in the series of 3-alkylaziridinones excludes achiral (acyclic) aziridinone isomers as intermediates at low tempera tures [6J. Similar stereochemical studies are still missing in the related series of iminoaziridines. Therefore, we report on the synthesis and thermolysis of the diastereomeric chiral racemic (E)- and (Z)-(4)[71 and non-racemic iminoaziridines (E,R)- and (Z,R)-4. Racemic Iminoaziridines (E)- and (Z)-4 Though a photochemical route to the iminoaziridines (E)- and (Z)-4 has been devised more recently, i. e. the phothe 2-iminoaziridines (E)- and (Z)-4, and (E,R)- and (Z.R)-4 (83% eel, respectively. The 1.3-elimination of hydrogen bromide from 9b is diastereoselective at -30 to -40°C [(E)-4:(Z)-4 = <10:>90). The diastereomers equilibrate at 36°C with (kEZ + k ZE) = (5.92 ± 0.08) . 10-5 S-I (K = kEZlkzE = 0.428 ± 0.013). - The thermolysis of (E)- and (Z)-4 in [D61benzene solution yields the imine 16 and methyl isocyanide (17). The decomposition follows the first-order rate law. The following Arrhenius and Eyring parameters are calculated from five rate constants obtained in the temperature range of 70-110°C: Ea = (115.2 ± 0.4) kJmol-t, IgA = (12.06 ± 0.28), AH* = (112.1 ± 0.4) kJmol- l , AS'" = (-23.9 ± 0.7) JK-I mol-I, AGj73K = 121 kJmol-1 . The enantiomeric excess of the surviving fraction of (E,R)- and (Z.R)-4 is unchanged after two half-lives at 80°C.
No abstract available
The selected area epitaxial overgrowth of narrow gap HgTe as well as wide gap CdTe and ZnTe on CdTe/GaAs substrates, which had been structured by dry etching techniques, has been investigated. A plasma etching process using a barrel reactor with CH\(_4\)-CH\(_2\) gases has been employed to prepare stripes with a width of about 1 μm with anisotropic as well as isotropic etching profiles. It has been found, that the selected area HgTe overgrowth takes place with a high local selectivity to the low index planes of the patterned surface. In contrast, the selected area overgrowth of the wide gap CdTe and ZnTe is controlled by anisotropic growth kinetics provided that the substrate temperature is not lower than 220°C and the starting surface consists of well developed low index crystallographic planes.
The structural properties of HgSe grown by molecular beam epitaxy (MBE) are investigated for different lattice mismatches to the substrate and various growth conditions. The growth rate is shown to depend strongly on the growth temperature above lOO°C as well as on the Hg/Se flux ratio. It has been found that the crystalline perfection and the electrical properties are mainly determined by the layer thickness, especially for the growth on highly lattice mismatched substrates. Changes in the surface morphology are related to growth parameters. Differences between the electrical behavior of MBE-grown and bulk HgSe are discussed. The electrical properties of HgSe contacts on p-ZnSe are investigated as a function of different annealing procedures.
The relationship between different degrees of intraspecific crowding of reedfrog tadpoles and their physiological responses to a deterioration of the natal pond water quality was examined under laboratory conditions. Tadpoles that were reared at a lower density metamorphosed significantly earlier than those raised at a higher density. As density increases, the average body length at metamorphosis decreases. However, at low tadpole density, a significantly higher diversity of body size classes among freshly metamorphosed froglets was observed than under more crowded conditions. Mortality increased during metamorphic climax and was inversely correlated with the tadpole density. In ephemeral ponds, an accumulation of nitrogenous wastes from metabolic processes and/or a concentration by evaporation in prolonged rainless periods can pose a considerable chemical stress to reedfrog tadpoles. Hyperolius viridiflavus ommatostictus responded to an increasing ammonia concentration with an activity increase of the ornithine cycle (intensified urea synthesis). hi contrast, Hyperolius marmoratus taeniatus exhibited a strong tolerance against high ammonia levels. A deterioration of the natal pond water quality caused H. v. ommatostictus and H. v. nitidulus tadpoles to adjust to harsher climatic conditions at the time of metamorphosis. This physiological preadjustment enabled the froglets to start feeding and growing immediately after metamorphosis even at low air humidity and rare precipitation events. In contrast, froglets that were raised in daily refreshed water exhibited high mortality rates if subjected to identical conditions. As one possible indicator of the actual climatic conditions prevailing in the surrounding terrestrial habitat, fluctuations in the water ammonia level are discussed.