STUDIES ON PLANT BILE PIGMENTS-6. PHOTOCHEMICALLY ASSISTED REACTION OF A-DIHYDROBILINDIONE WITH NUCLEOPHILES AS A MODEL FOR PHYTOCHROME INTERCONVERSION

From the A-dihydrobilindione 3. the pyridinium derivatives 6a,b and analogues thereof have been obtained by a formal nucleophilic substitution. The reaction is rationalized as a photochemically assisted oxidation of 3 with a subsequent regioselective addition of pyridine at C-5. By thermolysis. 6a.b yields back the parent bilin 3, together with an oxidation product. The significance of the reaction with respect to the phytochrome interconversion is discussed

Zwischen Marginalität und Allmachtsfantasien. Neuere Publikationen zum Pädagogikunterricht in der gymnasialen Oberstufe

Nach kurzen Hinweisen zur Institutionalisierung des Faches bzw. zur prekären Situation der Fachdidaktik Pädagogikunterricht und einem kurzen Überblick über die aktuelle Ausdifferenzierung des Diskursfeldes werden für den aktuellen Stand der fachdidaktischen Diskussion charakteristische Arbeiten von K. Beyer, E. Wortmann, E. Stiller und G. Koumides vorgestellt. Dabei werden Subjektorientierung und Handlungspropädeutik als der - trotz unterschiedlicher Akzentuierungen - gemeinsame Bezugspunkt dieser Arbeiten herausgestellt und das Fehlen einer empirischen Bedingungsanalyse des Faches sowie das Desinteresse an bildungssoziologischen Fragestellungen moniert. (DIPF/Orig.)Following a brief sketch of the institutionalization of the school subject pedagogics and of the precarious situation of the didactics of pedagogical instruction as well as a short survey on the recent differentiation of the field of discourse, the authors report on the studies by K. BEYER, E. WORTMANN, E. STILLER, and G. KOUMIDES, which are characteristic of the recent discussion on pedagogical didactics. Subject orientation and practice-related preparatory courses are revealed as a point of reference common to all of these studies, despite their different accentuations. However, the authors criticize the lack of an empirical analysis of the conditions of the subject pedagogics as well as the lack of interest in issues relating to educational sociology. (DIPF/Orig.

Acute tryptophan depletion in accordance with body weight: influx of amino acids across the blood–brain barrier

Acute tryptophan depletion (ATD) is a method of reducing central nervous serotonin (5-HT) synthesis in humans by administering an amino acid (AA) beverage lacking in tryptophan (TRP), the physiological precursor of 5-HT. However, to date, the use of conventional ATD protocols in children and adolescents was limited due to frequently observed side effects (e.g., vomiting and nausea). This study investigated the effects of diminished central nervous system 5-HT synthesis on plasma concentrations of relevant AAs and TRP influx into the brain in 24 healthy young adults using the ATD procedure Moja-De, a test protocol that has been used in preliminary research in youths. Twenty-four healthy participants received ATD and a TRP-balanced amino acid load (BAL) using a randomized double-blind within-subject crossover design. Plasma concentrations of the relevant AAs that compete with TRP on the same transport system were assessed at baseline and 90, 180, and 240 min after ATD/BAL intake. TRP influx across the blood–brain barrier was calculated using Michaelis–Menten kinetics with a correction for multiple substrate competition, indicating a significant decrease in TRP influx into the central nervous system under Moja-De. ATD Moja-De decreased TRP influx into the brain and central nervous system 5-HT synthesis safely and effectively and was well tolerated, allowing it to be used in children and adolescents. Future research into other secondary, compensatory effects induced by ATD in patients with neuropsychiatric disorders and healthy populations is needed. ATD Moja-De allows this type of research with a focus on a developmental viewpoint. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00702-012-0793-z) contains supplementary material, which is available to authorized users

Lost in bureaucracy : the experience of Rwandan refugee women in Cape Town

Bibliography: leaves 72-78

Dune ages in the sand deserts of the southern Sahara and Sahel

In this paper we aim to document the history of aeolian processes within the southern Sahara as part of the INQUA Dune Atlas. We review available luminescence ages for sand dunes across the southern Sahara to develop an improved understanding of the dune chronology on a regional basis and attempt to correlate periods of sand accumulation. This was achieved by analysing dune age by country, as well as by latitude and longitude. The results show a very patchy spatial distribution of dune ages with large gaps that encompass some of the largest sand seas. Despite these gaps, some related patterns in dune morphology and stratigraphy appear to be consistent between northern Nigeria and southern Mali where older linear dunes are distinct from younger Late Holocene transverse and barchanoid dunes. Elsewhere in Mauretania linear dunes with different orientations appear to have accumulated at different times, most likely in response to changes in atmospheric circulation. Regional climatic changes are identified where dunes are transgressed by lake deposits within endorehic basins. We identify four locations where dune accumulation is terminated by lacustrine transgressions, two of which, in Lake Chad and the Bodélé Depression, occur shortly after the last glacial maximum (LGM). The third example at Gobiero in Niger occurred later, in the early Holocene, around 8.4 ka and a fourth marks a later transgression of Palaeolake MegaChad after 4.7 ka. Larger-scale latitudinal and longitudinal distributions in dune ages across the southern Sahara do not show any consistent patterns, though this may be due to the small sample size relative to the study area. In addition, local variations in external controls such as wind regime, rainfall, vegetation and sand supply need to be considered, sometimes on a site by site basis. Limiting the analysis to dune ages determined using the single-aliquot regenerative-dose (SAR) protocol indicates a lack of dune preservation during the LGM and the Younger Dryas, times associated with increased dust input to the oceans which is assumed to indicate increased aeolian activity. The SAR dune dates suggest that preservation of dunes at the onset of succeeding humid intervals is an important component of the dune record. The most striking examples of this phenomenon occur where dunes are preserved within endorehic basins by lacustrine transgressions