1,485 research outputs found

    Party-Political Responses to the Alternative for Germany in Comparative Perspective

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    In September 2017, the Alternative for Germany (AfD) became the first far-right party to join the Bundestag in nearly seventy years. Yet, it was not the first time that a challenger party entered the parliament to the chagrin of the political establishment. After introducing the AfD, the BHE, the Greens, and the Party of Democratic Socialism (PDS), the article analyzes how established parties treated the newcomers and why they did so. This comparative perspective offers insights into the AfD’s challenge, how distinctive the policies toward the AfD have been, and why the established parties have dealt with the AfD as they have

    The Dynamics of Galaxy Pairs in a Cosmological Setting

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    We use the Millennium Simulation, and an abundance-matching framework, to investigate the dynamical behaviour of galaxy pairs embedded in a cosmological context. Our main galaxy-pair sample, selected to have separations under 250 kpc/h, consists of over 1.3 million pairs at redshift z = 0, with stellar masses greater than 10^9 Msun, probing mass ratios down to 1:1000. We use dark matter halo membership and energy to classify our galaxy pairs. In terms of halo membership, central-satellite pairs tend to be in isolation (in relation to external more massive galaxies), are energetically- bound to each other, and are also weakly-bound to a neighbouring massive galaxy. Satellite-satellite pairs, instead, inhabit regions in close proximity to a more massive galaxy, are energetically-unbound, and are often bound to that neighbour. We find that 60% of our paired galaxies are bound to both their companion and to a third external object. Moreover, only 9% of our pairs resemble the kind of systems described by idealised binary merger simulations in complete isolation. In sum, we demonstrate the importance of properly connecting galaxy pairs to the rest of the Universe.Comment: 25 pages, 14 figures, accepted by MNRA

    Mapping galaxy encounters in numerical simulations: The spatial extent of induced star formation

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    We employ a suite of 75 simulations of galaxies in idealised major mergers (stellar mass ratio ~2.5:1), with a wide range of orbital parameters, to investigate the spatial extent of interaction-induced star formation. Although the total star formation in galaxy encounters is generally elevated relative to isolated galaxies, we find that this elevation is a combination of intense enhancements within the central kpc and moderately suppressed activity at large galacto-centric radii. The radial dependence of the star formation enhancement is stronger in the less massive galaxy than in the primary, and is also more pronounced in mergers of more closely aligned disc spin orientations. Conversely, these trends are almost entirely independent of the encounter's impact parameter and orbital eccentricity. Our predictions of the radial dependence of triggered star formation, and specifically the suppression of star formation beyond kph-scales, will be testable with the next generation of integral-field spectroscopic surveys.Comment: 12 pages, 8 figures, accepted by MNRA

    Bulge mass is king: The dominant role of the bulge in determining the fraction of passive galaxies in the Sloan Digital Sky Survey

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    We investigate the origin of galaxy bimodality by quantifying the relative role of intrinsic and environmental drivers to the cessation (or `quenching') of star formation in over half a million local Sloan Digital Sky Survey (SDSS) galaxies. Our sample contains a wide variety of galaxies at z=0.02-0.2, with stellar masses of 8 < log(M*/M_sun) < 12, spanning the entire morphological range from pure disks to spheroids, and over four orders of magnitude in local galaxy density and halo mass. We utilise published star formation rates and add to this recent GIM2D photometric and stellar mass bulge + disk decompositions from our group. We find that the passive fraction of galaxies increases steeply with stellar mass, halo mass, and bulge mass, with a less steep dependence on local galaxy density and bulge-to-total stellar mass ratio (B/T). At fixed internal properties, we find that central and satellite galaxies have different passive fraction relationships. For centrals, we conclude that there is less variation in the passive fraction at a fixed bulge mass, than for any other variable, including total stellar mass, halo mass, and B/T. This implies that the quenching mechanism must be most tightly coupled to the bulge. We argue that radio-mode AGN feedback offers the most plausible explanation of the observed trends.Comment: Accepted to MNRAS. 32 pages, 27 figures. [This version is virtually identical to v1

    Thomomys bottae pocket gophers of the central Rio Grande Valley, New Mexico: local differentiation, gene flow, and historical biogeography

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    Representatives of two strongly differentiated geographic units within Thomomys bottae come in contact along the Rio Grande south of Albuquerque, New Mexico. The two forms share an average genic similarity of only 69%, and differ in karyotype by as much as 17 pairs of uniarmed autosomes. This high level of genic and chromosomal differentiation might suggest extremely limited introgression, or perhaps none at all. However, diagnostic alleles at several strongly differentiated loci were detected in contact zone populations of the opposite group, indicating that some gene flow does oc\u3c;ur. Suitable habitat and available land area are limited in the zone of contact, and these factors, in combination with the structure of local breeding populations of pocket gophers, contribute to restriction of gene flow through the contact zone. The measured width of the contact zone corresponds reasonably well with predictions derived from a neutral diffusion cline model under current estimates of gene flow rates and time of secondary contact

    The Alternative for Germany’s radicalization in historical-comparative perspective

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    This article chronicles the AfD’s rightward repositioning and compares it with the programmatic development of three postwar German parties on the ideological wings. By highlighting factors that tilt the balance of power away from moderate reformers towards hardliners, this comparative analysis sheds light on the conditions that lead a relatively successful party on the ideological wings, such as the AfD, to radicalize its programme. Four variables stand out: whether party hardliners take the blame for the recent election loss; whether they offer a convincing programmatic and strategic alternative to the reformers; whether changes in party composition strengthen hardliners; and whether external factors enhance their weight within the party. The essay concludes that the AfD’s radicalization was unusual, but not exceptional. It is however too early to conclude that the Federal Republic’s distinctive institutions and political culture no longer impose significant costs on parties that shift their programmes away from the centre

    What shapes a galaxy? - Unraveling the role of mass, environment and star formation in forming galactic structure

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    We investigate the dependence of galaxy structure on a variety of galactic and environmental parameters for ~500,000 galaxies at z<0.2, taken from the Sloan Digital Sky Survey data release 7 (SDSS-DR7). We utilise bulge-to-total stellar mass ratio, (B/T)_*, as the primary indicator of galactic structure, which circumvents issues of morphological dependence on waveband. We rank galaxy and environmental parameters in terms of how predictive they are of galaxy structure, using an artificial neural network approach. We find that distance from the star forming main sequence (Delta_SFR), followed by stellar mass (M_*), are the most closely connected parameters to (B/T)_*, and are significantly more predictive of galaxy structure than global star formation rate (SFR), or any environmental metric considered (for both central and satellite galaxies). Additionally, we make a detailed comparison to the Illustris hydrodynamical simulation and the LGalaxies semi-analytic model. In both simulations, we find a significant lack of bulge-dominated galaxies at a fixed stellar mass, compared to the SDSS. This result highlights a potentially serious problem in contemporary models of galaxy evolution.Comment: Accepted to MNRAS. 31 pages, 15 figure

    Synthesis of Triple-Stranded Diruthenium(II) Compounds

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    A series of ligands containing a 1,4-disubstituted 1,2,3-triazole unit have been used for the formation of triple-stranded dinuclear Ru(II) complexes. In contrast to the previously reported complexes of labile metals, the use of inert Ru(II) enabled stereoisomeric mixtures of triple-stranded diruthenium(II) complexes to be accessed. The chromatographic resolution of the enantiomers of a reported helicate containing a more rigid 1,4-xylyl spacer was carried out on cellulose. The ligand spacer was modified and as the flexibility increased the production of isomeric mixtures was detected; the mesocate and helicate forms were separated when an n-propyl spacer was used. This pair of diastereomers was found to exhibit photoconversion, a unique observation for Ru(II) compounds of this type. Partial separation via chromatographic resolution was achieved for compounds containing an n-butyl spacer, and the presence of a mesocate/helicate pair confirmed
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