Towards Design Principles for Data-Driven Decision Making: An Action Design Research Project in the Maritime Industry

Data-driven decision making (DDD) refers to organizational decision-making practices that emphasize the use of data and statistical analysis instead of relying on human judgment only. Various empirical studies provide evidence for the value of DDD, both on individual decision maker level and the organizational level. Yet, the path from data to value is not always an easy one and various organizational and psychological factors mediate and moderate the translation of data-driven insights into better decisions and, subsequently, effective business actions. The current body of academic literature on DDD lacks prescriptive knowledge on how to successfully employ DDD in complex organizational settings. Against this background, this paper reports on an action design research study aimed at designing and implementing IT artifacts for DDD at one of the largest ship engine manufacturers in the world. Our main contribution is a set of design principles highlighting, besides decision quality, the importance of model comprehensibility, domain knowledge, and actionability of results

New low surface brightness dwarf galaxies in the Centaurus group

We conducted an extensive CCD search for faint, unresolved dwarf galaxies of very low surface brightness in the whole Centaurus group region encompassing the Cen A and M 83 subgroups lying at a distance of roughly 4 and 5 Mpc, respectively. The aim is to significantly increase the sample of known Centaurus group members down to a fainter level of completeness, serving as a basis for future studies of the 3D structure of the group. Following our previous survey of 60 square degrees covering the M 83 subgroup, we extended and completed our survey of the Centaurus group region by imaging another 500 square degrees area in the g and r bands with the wide-field Dark Energy Survey Camera at the 4m Blanco telescope at CTIO. The limiting central surface brightness reached for suspected Centaurus members is $\mu_r \approx 29$ mag arcsec$^{-2}$, corresponding to an absolute magnitude $M_r \approx -9.5$. The images were enhanced using different filtering techniques. We found 41 new dwarf galaxy candidates, which together with the previously discovered 16 dwarf candidates in the M 83 subgroup amounts to almost a doubling of the number of known galaxies in the Centaurus complex, if the candidates are confirmed. We carried out surface photometry in g and r, and report the photometric parameters derived therefrom, for all new candidates as well as previously known members in the surveyed area. The photometric properties of the candidates, when compared to those of LG dwarfs and previously known Centaurus dwarfs, suggest membership in the Centaurus group. The sky distribution of the new objects is generally following a common envelope around the Cen A and M 83 subgroups. How the new dwarfs are connected to the intriguing double-planar feature recently reported by Tully et al. (2015) must await distance information for the candidates.Comment: 14 pages, 12 figures, accepted for publication in A&

New dwarf galaxy candidates in the Centaurus group

Recent studies of the distribution and kinematics of the Milky Way and Andromeda satellite galaxy systems have confirmed the existence of coplanar, corotating structures of galaxies. In addition to the 'missing satellite problem', these structures pose a major challenge to the standard $\Lambda$CDM scenario of structure formation. We complement the efforts made by the dwarf galaxy community to extend these studies to other nearby galaxy groups by systematically searching for faint, unresolved dwarf members with a low surface brightness in the Southern Centaurus group of galaxies. The aim is to determine whether these coplanar, corotating structures are a universal phenomenon. We imaged an area of 60 square degrees (0.3 Mpc$^2$) around the M83 subgroup with the wide-field Dark Energy Camera (DECam) at the CTIO 4 m Blanco telescope in $g$ and $r$ down to a limiting surface brightness of $\mu_r\approx 30$ mag arcsec$^{-2}$. Various image-filtering techniques were applied to the DECam data to enhance the visibility of extremely low-surface brightness objects. We report the discovery of 16 new dwarf galaxy candidates in the direction of the M83 subgroup, roughly doubling the number of known dwarfs in that region. The photometric properties of the candidates, when compared to those of the Local Group, suggest membership in the M83 subgroup. The faintest objects have a central star density of $\approx1.3 L_\odot$ pc$^{-2}$ and a total magnitude of $g = 20.25$, corresponding to $M_g = -9.55$ at the nominal distance of 4.9 Mpc. The sky distribution of the new objects is significantly prolonged toward Cen A, suggesting that many of them belong to the Cen A subgroup or a common halo. We also provide updated surface photometry for the brighter, known dwarf members in the surveyed area

Tip of the red giant branch distances to the dwarf galaxies dw1335-29 and dw1340-30 in the Centaurus group

The abundance and spatial distribution of dwarf galaxies are excellent empirical benchmarks to test models of structure formation on small scales. The nearby Centaurus group, with its two subgroups centered on CenA and M83, stands out as an important alternative to the Local Group for scrutinizing cosmological model predictions in a group of galaxies context. We have obtained deep optical images of three recently discovered M83 satellite galaxy candidates with the FORS2 instrument mounted on the Very Large Telescope. We aim to confirm their group membership and study their stellar population. Deep VI-band photometry is used to resolve the brightest stars in our targets. Artificial star tests are performed to estimate the completeness and uncertainties of the photometry. The color-magnitude diagrams reveal the red giant branch (RGB) stars allowing to use the Sobel edge detection method to measure the magnitude of the RGB tip and thus derive distances and group membership for our targets. The mean metallicity of the dwarf galaxies are further determined by fitting BASTI model isochrones to the mean RGB locus. We confirm the two candidates, dw1335-29 and dw1340-30, to be dwarf satellites of the M83 subgroup, with estimated distances of 5.03 +- 0.24 Mpc and 5.06 +- 0.24 Mpc, respectively. Their respective mean metallicities of = -1.79 +- 0.4 and = -2.27 +- 0.4 are consistent with the metallicity-luminosity relation for dwarf galaxies. The third candidate, dw1325-33, could not be resolved into stars due to insufficiently deep images, implying its distance must be larger than 5.3 Mpc. Using the two newly derived distances we assess the spatial distribution of the galaxies in the M83 subgroup and discuss a potential plane-ofsatellites around M83.Comment: 10 pages, 9 figures, accepted for publication in A&

The M101 group complex: new dwarf galaxy candidates and spatial structure

The fine details of the large-scale structure in the local universe provide important empirical benchmarks for testing cosmological models of structure formation. Dwarf galaxies are key object for such studies. Enlarge the sample of known dwarf galaxies in the local universe. We performed a search for faint, unresolved low-surface brightness dwarf galaxies in the M101 group complex, including the region around the major spiral galaxies M101, M51, and M63 lying at a distance 7.0, 8.6, and 9.0 Mpc, respectively. The new dwarf galaxy sample can be used in a first step to test for significant substructure in the 2D-distribution and in a second step to study the spatial distribution of the galaxy complex. Using filtering algorithms we surveyed 330 square degrees of imaging data obtained from the Sloan Digital Sky Survey. The images were visually inspected. The spatial distribution of known galaxies and candidates was analyzed transforming the system into a M101 eigenframe, using the geometrical alignment of the group. We discovered 15 new dwarf galaxies and carried out surface photometry in the g and r bands. The similarity of the photometric properties of these dwarfs to those of Local Group dwarfs suggest membership to the M101 group complex. The sky distribution of the candidates follows the thin planar structure outlined by the known members of the three subgroups. The ~3Mpc long filamentary structure has a rms thickness of 67 kpc. The planar structure of the embedded M101 subgroup is even thinner, with rms=46 kpc. The formation of this structure might be due to the expansion of the Local Void to which it borders. Other implications are discussed as well. We show the viability of SDSS data to extend the sample of dwarfs in the local universe and test cosmological models on small scales.Comment: 12 pages, 8 figures, accepted for publication in A&

Planes of satellites in the nearby Universe

Since the mid 70ies it is known that the dwarf galaxies around the Milky Way are arranged in a thin, polar structure. The arrangement and motion within this structure has been identified as a severe challenge to the standard model of cosmology, dubbed as the plane of satellites problem. More observational evidence for such structures has been put forward around other galaxies, such as the Andromeda galaxy, Cen\,A or NGC\,253, among others, adding to the previously identified tensions. Solutions to the plane of satellite problem should therefore not only be tailored to the Milky Way, but need to explain all these different observed systems and environments.Comment: 5 pages. Submitted to the Proceedings of IAU Symposium 379: Dynamical Masses of Local Group Galaxie

Thermodynamic characterization of an engineered tetracycline-binding riboswitch

Riboswitches reflect a novel concept in gene regulation that is particularly suited for technological adaptation. Therefore, we characterized thermodynamically the ligand binding properties of a synthetic, tetracycline (tc)-binding RNA aptamer, which regulates gene expression in a dose-dependent manner when inserted into the untranslated region of an mRNA. In vitro, one molecule of tc is bound by one molecule of partially pre-structured and conformationally homogeneous apo-RNA. The dissociation constant of 770 pM, as determined by fluorimetry, is the lowest reported so far for a small molecule-binding RNA aptamer. Additional calorimetric analysis of RNA point mutants and tc derivatives identifies functional groups crucial for the interaction and including their respective enthalpic and entropic contributions we can propose detailed structural and functional roles for certain groups. The conclusions are consistent with mutational analyses in vivo and support the hypothesis that tc-binding reinforces the structure of the RNA aptamer, preventing the scanning ribosome from melting it efficiently