title: Reversible pyranyl complex formation and the mechanism of rearrangement to (η5-6-oxocycloheptadienyl)Mn(CO)3 complexes in the reaction of β-cyclomanganated 1,5-diarylpenta-1,4-dien-3-ones and alkynes; the crystal structure of [2,4-diphenyl-6-(2-phenylethenyl)pyranyl-η5]tricarbonylmanganese

authors: Mace, Wade

subjects: Manganese

abstract: 1-Phenyl-2-[(E)-3-phenylprop-2-en-1-oyl-κO]ethenyl-κC1]tetracarbonylmanganese (1a) reacts with PhCCH in CCl4 at room temperature to form [2,4-diphenyl-6-(2-phenylethenyl)pyranyl-η5]tricarbonylmanganese (2a), whose X-ray crystal structure is reported to complement that of its isomer [6-oxo-2,4,7-triphenylcyclohepta-1,4-dienyl-1,2,3,4,5-η]tricarbonylmanganese (3a), previously obtained from the reaction under reflux; but for 1a and PhCCPh the pyranyl complex cannot be isolated before rearrangement to the 3a analogue occurs. More forcing reaction conditions for 1a with Me3SiCCH and for [1-(2-trifluoromethylphenyl)-2-[(E)-3-(2-trifluoromethylphenyl)prop-2-en-1-oyl-κO]ethenyl-κC1]tetracarbonylmanganese (1b) with Me3SiCCH and PhCCH give new analogues of 3a where previously only 2a analogues had been isolated.
The reaction in CCl4 under reflux of PhCCH and the β-deuterio analogue of 1a, [1-phenyl-2-[(E)-3-phenylprop-2-en-1-oyl-3d-κO]ethenyl-κC1]tetracarbonylmanganese, gave deuteriated 3a with exo-D at the α-carbon, C7. This is inconsistent with the Mn-mediated Ph migration mechanism originally proposed to accommodate the endo position of Ph in 3a, and instead it implicates a cyclopropyl carbonyl-addition intermediate or a cyclopropyl acyl-substitution transition state in the key rearrangement step for 2a → 3a.

text: Reversible pyranyl complex formation and the mechanism of rearrangement to (η5-6-oxocycloheptadienyl)Mn(CO)3 complexes in the reaction of β-cyclomanganated 1,5-diarylpenta-1,4-dien-3-ones and alkynes; the crystal structure of [2,4-diphenyl-6-(2-phenylethenyl)pyranyl-η5]tricarbonylmanganese 1-Phenyl-2-[(E)-3-phenylprop-2-en-1-oyl-κO]ethenyl-κC1]tetracarbonylmanganese (1a) reacts with PhCCH in CCl4 at room temperature to form [2,4-diphenyl-6-(2-phenylethenyl)pyranyl-η5]tricarbonylmanganese (2a), whose X-ray crystal structure is reported to complement that of its isomer [6-oxo-2,4,7-triphenylcyclohepta-1,4-dienyl-1,2,3,4,5-η]tricarbonylmanganese (3a), previously obtained from the reaction under reflux; but for 1a and PhCCPh the pyranyl complex cannot be isolated before rearrangement to the 3a analogue occurs. More forcing reaction conditions for 1a with Me3SiCCH and for [1-(2-trifluoromethylphenyl)-2-[(E)-3-(2-trifluoromethylphenyl)prop-2-en-1-oyl-κO]ethenyl-κC1]tetracarbonylmanganese (1b) with Me3SiCCH and PhCCH give new analogues of 3a where previously only 2a analogues had been isolated.
The reaction in CCl4 under reflux of PhCCH and the β-deuterio analogue of 1a, [1-phenyl-2-[(E)-3-phenylprop-2-en-1-oyl-3d-κO]ethenyl-κC1]tetracarbonylmanganese, gave deuteriated 3a with exo-D at the α-carbon, C7. This is inconsistent with the Mn-mediated Ph migration mechanism originally proposed to accommodate the endo position of Ph in 3a, and instead it implicates a cyclopropyl carbonyl-addition intermediate or a cyclopropyl acyl-substitution transition state in the key rearrangement step for 2a → 3a.

year: 2005-07-01

title: Effects of population size on singing behavior of a rare duetting songbird

authors: Valderrama Ortiz, Sandra Viviana

subjects: behavioral conservation

abstract: Although the genetic and ecological effects of population declines in endangered species have been well studied, little is known of the social consequences. Changes in signaling behavior may result in disrupted communication and affect both reproductive and conflict-resolution activities. The North Island Kōkako (Callaeas wilsoni) is an endangered, duetting (i.e., alternating, coordinated singing by mated pairs) songbird endemic to New Zealand temperate rain forests. Scattered populations (approximately 1500 individuals in 13 surviving and 11 translocated populations) in isolated conservation areas of different sizes have been rescued from extirpation and are currently recovering. We examined key song attributes of the Kōkako to assess whether population size or growth rate are related to song complexity, the reduction of which may compromise effective communication. We analyzed song repertoire size and phrase-type sharing (i.e., Jaccard index of similarity), vocal performance (singing rates, song switching rates, and diversity of phrase types), and song syntactical characteristics (i.e., unpredictability in sequences of phrase types) in surviving and translocated populations (populations of approximately 19–250 territorial individuals). Population size was positively correlated with a population's song repertoire, song diversity, and switching of song phrase types and negatively correlated with shared phrase types and variation in syntactical structure of songs. Population growth rate correlated positively with pair repertoire size, population repertoire size, and singing rates during song bouts. As for solo-singing species in fragmented landscapes, songs in the fragmented populations of Kōkako appear to be undergoing microevolution as occurs in island colonization events. Our results suggest that vocal changes in small populations could affect population establishment and growth, particularly in multiple-source translocations. We believe measurement of vocal behavior could be used as a supplement to periodic population censuses to allow more frequent monitoring of population size.

text: Effects of population size on singing behavior of a rare duetting songbird Although the genetic and ecological effects of population declines in endangered species have been well studied, little is known of the social consequences. Changes in signaling behavior may result in disrupted communication and affect both reproductive and conflict-resolution activities. The North Island Kōkako (Callaeas wilsoni) is an endangered, duetting (i.e., alternating, coordinated singing by mated pairs) songbird endemic to New Zealand temperate rain forests. Scattered populations (approximately 1500 individuals in 13 surviving and 11 translocated populations) in isolated conservation areas of different sizes have been rescued from extirpation and are currently recovering. We examined key song attributes of the Kōkako to assess whether population size or growth rate are related to song complexity, the reduction of which may compromise effective communication. We analyzed song repertoire size and phrase-type sharing (i.e., Jaccard index of similarity), vocal performance (singing rates, song switching rates, and diversity of phrase types), and song syntactical characteristics (i.e., unpredictability in sequences of phrase types) in surviving and translocated populations (populations of approximately 19–250 territorial individuals). Population size was positively correlated with a population's song repertoire, song diversity, and switching of song phrase types and negatively correlated with shared phrase types and variation in syntactical structure of songs. Population growth rate correlated positively with pair repertoire size, population repertoire size, and singing rates during song bouts. As for solo-singing species in fragmented landscapes, songs in the fragmented populations of Kōkako appear to be undergoing microevolution as occurs in island colonization events. Our results suggest that vocal changes in small populations could affect population establishment and growth, particularly in multiple-source translocations. We believe measurement of vocal behavior could be used as a supplement to periodic population censuses to allow more frequent monitoring of population size.

year: 2013

title: Transformative pedagogy and language learning in Maori and Irish contexts

authors: Glynn, Ted

subjects: transformative pedagogy

abstract: Establishing positive learning communities in classrooms where pedagogies are socially and culturally responsive and centred on shared life experiences is critical for the revitalisation of minoritised languages such as Irish and Māori, which lack the dominance and power of the wider languages of government and communication. Transformative pedagogy and pedagogical re-positioning of teachers are essential to legitimising and affirming minoritised languages in the classroom. Three small-scale New Zealand studies of emerging literacy in Māori are introduced, exemplifying a responsive and transformative pedagogy that enables teachers to position themselves as socially and culturally responsive participants within classroom contexts. These studies offer strategies that might facilitate the development of similar transformative pedagogy in Irish contexts also.

text: Transformative pedagogy and language learning in Maori and Irish contexts Establishing positive learning communities in classrooms where pedagogies are socially and culturally responsive and centred on shared life experiences is critical for the revitalisation of minoritised languages such as Irish and Māori, which lack the dominance and power of the wider languages of government and communication. Transformative pedagogy and pedagogical re-positioning of teachers are essential to legitimising and affirming minoritised languages in the classroom. Three small-scale New Zealand studies of emerging literacy in Māori are introduced, exemplifying a responsive and transformative pedagogy that enables teachers to position themselves as socially and culturally responsive participants within classroom contexts. These studies offer strategies that might facilitate the development of similar transformative pedagogy in Irish contexts also.

year: 2009