63,182 research outputs found
An Extremely Carbon-rich, Extremely Metal-poor Star in the Segue 1 System
We report the analysis of high-resolution, high-S/N spectra of an extremely
metal-poor, extremely C-rich red giant, Seg 1-7, in the Segue 1 system -
described in the literature alternatively as an unusually extended globular
cluster or an ultra-faint dwarf galaxy. The radial velocity of Seg 1-7
coincides precisely with the systemic velocity of Segue 1, and its chemical
abundance signature of [Fe/H] = -3.52, [C/Fe] = +2.3, [N/Fe] = +0.8, [Na/Fe] =
+0.53, [Mg/Fe] = +0.94, [Al/Fe] = +0.23 and [Ba/Fe] < -1.0 is similar to that
of the rare and enigmatic class of Galactic halo objects designated CEMP-no
(Carbon-rich, Extremely Metal-Poor and with no enhancement (over solar ratios)
of heavy neutron-capture elements). This is the first star in a Milky Way
``satellite'' that unambiguously lies on the metal-poor, C-rich branch of the
Aoki et al. (2007) bimodal distribution defined by field halo stars in the
([C/Fe], [Fe/H])-plane. Available data permit us only to identify Seg 1-7 as a
member of an ultra-faint dwarf galaxy or as debris from the Sgr dwarf
spheroidal galaxy. In either case, this demonstrates that at extremely low
abundance, [Fe/H ] < -3.0, star formation and associated chemical evolution
proceeded similarly in the progenitors of both the field halo and satellite
systems. By extension, this is consistent with other recent suggestions the
most metal-poor dwarf spheroidal and ultra-faint dwarf satellites were the
building blocks of the Milky Way's outer halo.Comment: 18 pages, 2 figures, submitted to Astrophysical Journal Letter
A Frame Bundle Generalization of Multisymplectic Momentum Mappings
This paper presents generalized momentum mappings for covariant Hamiltonian
field theories. The new momentum mappings arise from a generalization of
symplectic geometry to , the bundle of vertically adapted linear frames
over the bundle of field configurations . Specifically, the generalized
field momentum observables are vector-valued momentum mappings on the
vertically adapted frame bundle generated from automorphisms of . The
generalized symplectic geometry on is a covering theory for
multisymplectic geometry on the multiphase space , and it follows that the
field momentum observables on are generalized by those on .
Furthermore, momentum observables on produce conserved quantities along
flows in . For translational and orthogonal symmetries of fields and
reparametrization symmetry in mechanics, momentum is conserved, and for angular
momentum in time-evolution mechanics we produce a version of the parallel axis
theorem of rotational dynamics, and in special relativity, we produce the
transformation of angular momentum under boosts.Comment: 23 page
Application of electrospray mass spectrometry to the analysis of lipids : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Food Technology at Massey University
This work investigated the application of electrospray mass spectrometry (MS) to the elucidation of lipid structure, especially related to milkfat. This was the first time that the instrument in our laboratory had been used for this purpose. Standard samples of triacylglycerols (TAGs) were prepared in 1,2 dichloroethane: acetonitrile:formic acid (63:35:2) at approximately 0.005 mg/mL and were then used to optimise and quantify the ion signal (response) generated by the Perkin Elmer Sciex API300 electrospray mass spectrometer. Both MS and tandem MS experiments were performed. In the spectra, the TAG molecule was seen as an ammonium ion adduct (M+NH4)+.
It was found that the relative responses of diacylglycerol (DAG) ions, formed during front end fragmentation of the (M+NH4)+
ion, depended on the position of the 'lost' fatty acid on the glycerol backbone and its carbon number, with the former rather than the latter being the more critical. This information enabled the fatty acid esterified to the sn2 carbon of the glycerol backbone to be identified, and also demonstrated that it was possible to identify each of the fatty acids in a TAG molecule accurately by molecular and DAG ion identification. MS/MS experiments were performed on DAG ions, rather than parent ions, to identify and measure the response of acylium ions generated during collision-assisted dissociation (CAD). In contrast to the response of the DAG ions above, it was found that the response of these acylium ions was dependent on their carbon number and degree of saturation rather than the position that the fatty acid had held on the glycerol backbone. Optimal voltage settings for analysis of TAGs by infusion MS were obtained, which gave good quality spectra and ample amounts of molecular and DAG ions. With this information, a novel liquid chromatography-mass spectrometry (LC-MS) method, which was able to characterise the TAGs in a number of complex lipid samples, was developed. The method was used to elucidate differences in the TAG structure of different bovine milkfats and also differences in fat from milk of various mammalian species
Recommended from our members
Toxic waters: Ibrahim Hazboun and the struggle for a Dead Sea concession, 1913-1948
In 1930, the British Colonial Office signed a formal agreement with Moshe Novomeysky, a Jewish Russian mining engineer from Siberia and committed Zionist, creating Palestine Potash Ltd (PPL). This company was given exclusive rights over the extraction of mineral salts from the Dead Sea for a period of 50 years and was the predecessor to todayâs Israeli enterprise, the Dead Sea Works (DSW). Reading through Novomeyskyâs memoirs, as well as the handful of Israeli histories of the Dead Sea industry, the concession appears as a hard-fought Zionist victory in the face of stiff opposition within British parliamentary circles. From this point, the formation and subsequent success of PPL is described as an important early stage in the attempt to build up a national chemical industry in the state of Israel. Arab Palestinians are almost entirely invisible in this story, save for Novomeyskyâs occasional mention of PPLâs âfriendly relationsâ with Arab communities in the area. Focusing on the story of Ibrahim Hazboun, a Catholic merchant trader from Bethlehem, this article retells the story of the Dead Sea concession from a local Arab perspective, employing a variety of sources, both written and oral, to fill in the gaps left by the colonial and Zionist archives. Contrary to the claims of British and Zionist officials, it is shown that Arab Palestinians had been intensely interested in exploiting the riches of the Dead Sea since the end of Ottoman rule, and they continued to express their interest throughout the Mandate period. Weaving Ibrahimâs personal story into the bigger picture of national opposition to the Dead Sea project, it is argued that this neglected historical episode can serve as a window onto the wider problems facing the Arab merchant classes during the transition from Ottoman to British rule in Palestin
Exporting the Holy Land: artisans and merchant migrants in Ottoman-era Bethlehem
This article explores an aspect of Arab migration in the nineteenth century that is often retold in popular memory but rarely discussed in academic work: that of Bethlehem merchants and the âHoly Landâ wares they sold. Beginning roughly in the 1850s, these travelling salesmen established trading connections in all corners of the globe, constituting one of the earliest manifestations of the wider movement of Arabic-speaking people away from the Ottoman Empire in the nineteenth and early twentieth centuries. To properly contextualize the emergence and significance of this merchant activity, the article firstly offers an account of how Bethlehem came to be the manufacturing center of a global industry in religious souvenirs. It then turns to the nineteenth-century merchants themselves, exploring their multi-directional
trajectories in the nineteenth century. Through these twin dynamics of production and circulation, the article questions some of the commonly held assumptions about
the nature of the nineteenth-century âArab diasporaâ or mahjar
Why the Cameron-Clegg coalition will be a shock to both Tory and Liberal Democrat voters
There has been intensive speculation about how Conservative and Liberal Democrat voters will react to the coalition government cemented in their name. Pippa Norris of Harvard University has the first stunning data, showing that in 2010 Tories predominantly put the far right parties as their second preference, and Liberal Democrat voters predominantly wanted Labour as their second choice
- âŠ