Kinematics of the ring-like nebula SuWt 2

We present the first detailed spatio-kinematical analysis and modelling of the southern planetary nebula SuWt 2. This object presents a problem for current theories of planetary nebula formation and evolution, as it is not known to contain a central post-main-sequence star. Deep narrow-band [NII]6584Å images reveal the presence of faint bipolar lobes emanating from the edges of the nebular ring. Long-slit observations of the Ha and [NII]6584Å emission lines were obtained using the ESO (European Southern Observatory) Multi-Mode Instrument on the 3.6-m ESO New Technology Telescope. The spectra reveal the nebular morphology as a bright torus encircling the waist of an extended bipolar structure. By deprojection, the inclination of the ring is found to be 68° +/- 2° (cf. ~90° for the double A-type binary believed to lie at the centre of the nebula), and the ring expansion velocity is found to be 28 kms-1. Our findings are discussed with relation to possible formation scenarios for SuWt 2. Through comparison of the nebular heliocentric systemic velocity, found here to be -25 +/- 5km s-1, and the heliocentric systemic velocity of the double A-type binary, we conclude that neither component of the binary could have been the nebular progenitor. However, we are unable to rule out the presence of a third component to the system, which would have been the nebula progenitor.

A study of Heck cyclization reactions to form phenanthridine ring systems

A survey of conditions for the palladium catalyzed intramol. Heck cyclization of protected amines has shown that the Herrmann-Beller palladacycle can be exploited under 'cationic' conditions to provide a robust and rapid route (

A Ring Rearrangement Approach to the Synthesis of Benzo[b]quinolizine and Benzoindolizine Architectures

An efficient ring rearrangement metathesis (RRM) approach to the synthesis of benzo[b]quinolizine and benzoindolizine systems from N-propargyl-phenanthridine derivatives is reported. A Hovel use of flash vacuum pyrolysis (FVP) for the Boc-deprotection of acid-sensitive substrates is also disclosed.

Synthesis of the alkaloid homaline in ( ) and natural (S,S)-(-) forms, using amination and transamidative ring expansion in liquid ammonia.

Crombie, Leslie; Haigh, David; Jones, Raymond C. F.; Mat-Zin, A.Rasid. Dep. Chem., Univ. Nottingham, Nottingham, UK. Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999) (1993), (17), 2047-54. CODEN: JCPRB4 ISSN: 0300-922X. Journal written in English. CAN 120:164608 AN 1994:164608 CAPLUS (Copyright (C) 2009 ACS on SciFinder (R)) Abstract The alkaloid homaline I was prepd. in (?) and natural (S,S)-(-) forms. Linking of 2-azacyclooctanone units either directly or successively using 1,4-dihalogenobutanes or 1,4-dihalogenobut-2-ynes is examd. (?)-5-Methyl-4-phenyl-1,5-diazacyclooctan-2-one is first made by a 2,2'-dithiodipyridine/triphenylphosphine-mediated cyclization, and then by amination and transamidative ring expansion from N-(3-chloropropyl)-4-phenylazetidin-2-one in liq. ammonia, followed by N-methylation. Coupling through a 1,4-dihalogenobutane of either the N-methylated azalactam, or the unmethylated azalactam followed by methylation, gave homaline in (?) and meso forms. (R)-(-)-phenylglycine was converted via (S)-?-phenyl-?-alanine into an (S)-?-lactam which was then alkylated with 1-bromo-3-chloropropane, and aminated and ring expanded in liq. ammonia. Coupling of the homochiral azalactam (2 mol) so formed with 1,4-dibromobutane, followed by N-methylation, gave (S,S)-(-)-homaline identical with the natural material.

Split slot ring spatial quasi-circulator for RCS characterisation

A prototype X-band scale model for a quasi-optical three-port circulator utilising a double-layer circularly polarising frequency selective surface is proposed. The operating principles and measured characteristics of the device are discussed. A prototype device operating at 9.9 GHz has been built and validated experimentally. The port 1 to port 2 insertion loss of the quasi-circulator has been measured to be 2 dB, while port 1 to port 3 isolation is 16 dB. It is demonstrated that port 1 to 3 isolation can be increased to 25 dB by embedding the quasi-circulator in a feedforward setup.

Amplitude and Phase Controlled Reflectarray Element Based on an Impedance Transformation Unit

An architecture to simultaneously affect both amplitude and phase control from a reflectarray element using an impedance transformation unit is demonstrated. It is shown that a wide range of control is possible from a single element, removing the conventional necessity for variable sized elements across an array in order to form a desired reflectarray far-field pattern. Parallel plate waveguide measurements for a 2.2 GHz prototype element validate the phase and amplitude variation available from the element. It is demonstrated that there is sufficient control of the element's reflection response to allow Dolph-Tschebyscheff weighting coefficients for major-lobe to side-lobe ratios of up to 36 dB to be implemented.

Confirming the Existence of Gaps and Depletions in the Irish Oak Tree-Ring Record

In the course of building the 7000 year Belfast long oak chronology a series of depletion problems were encountered. These problems were overcome by 1984 when the completion of the long chronology was announced. The solution to the bridging of the various ‘gaps’ in the Irish chronology lay in the use of long sections of oak chronology from Britain. Now that a quarter of a century has elapsed and large numbers of additional oak samples, and site assemblages, have been accumulated it seems reasonable to review the ‘gaps’ in order to see if the Irish chronology could now be constructed without the use of British material. That is, are the depletion periods in the Irish chronology still evident, and if so, what might they imply about past conditions and human populations? The perhaps surprising conclusion is that the original depletions are still evident after 25 years of quasi-random sampling by archaeologists and palaeoecologists throughout Ireland.

A ring-closing metathesis approach to the bicyclo[4.3.1]decane core of caryolanes

A synthesis of highly substituted and sterically congested bicyclo[4.3.1]decenes, a structure embedded in the core 4,7,6-tricyclic system of natural caryolanes, was successfully achieved via a ring-closing metathesis (RCM) reaction of syn-1,3-diene substituted cyclohexanols. The construction of the diene substrates, starting from 4-acetoxy-3-methyl-2-cyclohexen-1-one, employed diastereoselective copper-mediated conjugate addition and Grignard reactions. An X-ray crystal structure determination of a key synthetic intermediate confirmed the relative stereochemistry of the RCM bicyclic product.

325GHz Single Layer Sub-Millimeter Wave FSS Based Split Ring Linear to Circular Polarisation Convertor

A single layer, frequency selective surface based, sub-millimeter wave transmission polarizer is presented that converts incident slant linear 45° polarization into circular polarization upon transmission. The polarization convertor consists of a 30 mm diameter 10 thick silicon reinforced metalized screen containing 2700 resonator cells and perforated with nested split ring slot apertures. The screen was designed and optimized using CST Microwave Studio and predictions were validated experimentally by transmission measurements over the 250-365 GHz frequency range. This frequency range is used for remote environmental monitoring and 325 GHz represents a molecular emission line for H2O. The results obtained show good agreement between measured and modeled predictions. The measured 3 dB axial ratio bandwidth was 11.75%, measured minimum Axial Ratio was 0.19 dB and the measured insertion loss of the single layer screen was 3.38 dB

Culture and the Irish Border:Spaces for Conflict Transformation

The Irish border has been described as a ‘natural’ cultural divide between the island's two dominant indigenous ethno-national communities. However, an examination of key resources of ethno-national group culture - religion, sport and language - provides evidence to challenge this representation. Moreover, in the post-1994 period of conflict transformation, evidence is also presented to support the proposition that the Irish border region has developed into a cultural space in which Irish nationalist and Ulster unionist ethno-national communities can explore cultural differences and commonalities through cross-border, cross-community contact and communication in small group encounters. This space underpins the reconfiguration of the border from barrier to political bridge between North and South. European Union (EU) Peace programmes for Ireland, beginning in 1995, provided the support for a cross-border approach to escaping the cage of ethno-national conflict in Northern Ireland. However, post-2004 EU enlargement signalled the beginning of the end for EU Peace funding and severe economic recession has undermined the expectation of British-Irish intergovernmental intervention to support cross-border partnerships and their work. Therefore, the outlook for the sustainability of this cross-border cultural space is gloomy with potentially deleterious consequences for the continued reconfiguration of the border from barrier to bridge.

Confronting the Settler Legacy: Indigenisation and Transformation in South Africa and Zimbabwe

This article examines attempts to negotiate a perceived residual dominance of settler populations in South Africa and Zimbabwe by means of developmental and cultural policies deemed necessary to restore sovereignty to Africans. Indigenisation has become a preferred strategy for reconstructing post-colonial states in Africa: indigenisation of the economy as part of a Third Chimurenga in Zimbabwe and Black Economic Empowerment in the socio-cultural context of Ubuntu in South Africa. These are issues arising from the regional legacy of contested and uneven transitions to majority rule. Identifying how governments frame the ‘settler problem’, and politicise space in doing so, is crucial for understanding post-colonial politics. Indigenisation in Zimbabwe allows the government to maintain a network of patronage and official rhetoric is highly divisive and exclusivist although couched in terms of reclaiming African values and sovereignty. Revival of Ubuntu as a cultural value system in South Africa facilitates a more positive approach to indigenisation, although Black Economic Empowerment displays elitist tendencies and cultural transformation remains controversial and elusive. The perceived need to anchor policy in socially acceptable (i.e., ostensibly indigenous/traditional) contexts has become a prominent feature of post-colonial politics and is indicative of an indigenous turn in Southern African politics.