Thomassen's Choosability Argument Revisited

Thomassen (1994) proved that every planar graph is 5-choosable. This result was generalised by {\v{S}}krekovski (1998) and He et al. (2008), who proved that every $K_5$-minor-free graph is 5-choosable. Both proofs rely on the characterisation of $K_5$-minor-free graphs due to Wagner (1937). This paper proves the same result without using Wagner's structure theorem or even planar embeddings. Given that there is no structure theorem for graphs with no $K_6$-minor, we argue that this proof suggests a possible approach for attacking the Hadwiger Conjecture

Thirty-fold: Extreme gravitational lensing of a quiescent galaxy at z=1.6z=1.6

We report the discovery of eMACSJ1341-QG-1, a quiescent galaxy at $z=1.594$ located behind the massive galaxy cluster eMACSJ1341.9$-$2442 ($z=0.835$). The system was identified as a gravitationally lensed triple image in Hubble Space Telescope images obtained as part of a snapshot survey of the most X-ray luminous galaxy clusters at $z>0.5$ and spectroscopically confirmed in ground-based follow-up observations with the ESO/X-Shooter spectrograph. From the constraints provided by the triple image, we derive a first, crude model of the mass distribution of the cluster lens, which predicts a gravitational amplification of a factor of $\sim$30 for the primary image and a factor of $\sim$6 for the remaining two images of the source, making eMACSJ1341-QG-1 by far the most strongly amplified quiescent galaxy discovered to date. Our discovery underlines the power of SNAPshot observations of massive, X-ray selected galaxy clusters for lensing-assisted studies of faint background populations

INTERVIEW: Knowledge and Terminology Management at the Danish National Board of Social Services

Margrethe H. Møller interviews David Rosendahl(translator/coauthor: Birthe Toft)“We need to do more than simply create classifications” The concept secretariat of the Danish National Board of Social Services carries out terminology and classification work in connection with IT projects, among others, in the field of social services. This work is interesting for several reasons. On the one hand, terminology work obviously contributes to enhanced efficiency and transparency from the points of view of all types of users. On the other hand, some social services professionals are skeptical vis-à-vis the terminology projects because they fear unification and standardization of their professionalism and working procedures in connection with the introduction of new IT systems. And finally, a number of ethical issues have to be taken into consideration when deciding on terminology in the social services field. All in all, target group and communicative aspects become central to the effort.David Rosendahl Terminology consultant at the Danish National Board of Social ServicesThe Danish National Board of Social Services(“Socialstyrelsen”) is an independent subdivision of The Ministry of Social Affairs and Integration. The Board aims to promote new development and initiatives in social services while also supporting and counselling local authorities in providing services to citizens, i.e. children, young people, socially marginalised groups, elderly and disabled

Multiplication and Composition in Weighted Modulation Spaces

We study the existence of the product of two weighted modulation spaces. For this purpose we discuss two different strategies. The more simple one allows transparent proofs in various situations. However, our second method allows a closer look onto associated norm inequalities under restrictions in the Fourier image. This will give us the opportunity to treat the boundedness of composition operators.Comment: 49 page

INTERVIEW: Knowledge and Terminology Management at Crisplant

Margrethe H. Møller interviews Lisbeth Kjeldgaard Almsten(translator/coauthor: Birthe Toft)“If you think that terminology work is simply a matter of buying terminology management software and getting started, you are in for trouble” At Crisplant, we have been doing terminology management for the past 20 years. Today, term bases are used not just for terminology-oriented term management. Recording other types of master data needed by all kinds of professionals in the enterprise is equally important. Within the past year, Crisplant has been acquired by the German BEUMER group, which means that the terminological resources of the two enterprises are in the process of being integrated. The challenges presented by this process demonstrate the importance of adhering to terminological principles when recording terminology resources, while at the same time reminding us what an essential discipline terminology management really is, in enterprise practice as well as in education. Lisbeth Kjeldgaard AlmstenProject Manager & Linguistic Coordinator at Crisplant.Lisbeth Kjeldgaard Almsten is dedicated to language technology, and she plays the role of coordinator vis-à-vis her colleagues in the BEUMER Group, who use the same language technology tools as the ones she works with

Discovery of an overdensity of faint red galaxies in the vicinity of the z=1.786 radio galaxy 3C 294

We report the discovery of an overdensity of faint red galaxies in the vicinity of the z=1.786 radio galaxy 3C 294. The overdensity, discovered in a 84 min Ks-band ISAAC/VLT image is significant at the 2.4 sigma level (compared to the local field density), and overlaps with the extended X-ray emission around 3C 294 detected with the Chandra X-ray Observatory. The near-infrared colours of the galaxies making up the overdensity show a large scatter and the galaxies do not follow a red sequence in the colour magnitude diagram. If the galaxies are in a cluster at z=1.786 they must be dominated by young stellar populations with different star-formation histories.Comment: Accepted for publication in MNRA

Quasicontinuum γ\gamma-decay of 91,92^{91,92}Zr: benchmarking indirect (n,γn,\gamma) cross section measurements for the ss-process

Nuclear level densities (NLDs) and $\gamma$-ray strength functions ($\gamma$SFs) have been extracted from particle-$\gamma$ coincidences of the $^{92}$Zr($p,p' \gamma$)$^{92}$Zr and $^{92}$Zr($p,d \gamma$)$^{91}$Zr reactions using the Oslo method. The new $^{91,92}$Zr $\gamma$SF data, combined with photonuclear cross sections, cover the whole energy range from $E_{\gamma} \approx 1.5$~MeV up to the giant dipole resonance at $E_{\gamma} \approx 17$~MeV. The wide-range $\gamma$SF data display structures at $E_{\gamma} \approx 9.5$~MeV, compatible with a superposition of the spin-flip $M1$ resonance and a pygmy $E1$ resonance. Furthermore, the $\gamma$SF shows a minimum at $E_{\gamma} \approx 2-3$~MeV and an increase at lower $\gamma$-ray energies. The experimentally constrained NLDs and $\gamma$SFs are shown to reproduce known ($n, \gamma$) and Maxwellian-averaged cross sections for $^{91,92}$Zr using the {\sf TALYS} reaction code, thus serving as a benchmark for this indirect method of estimating ($n, \gamma$) cross sections for Zr isotopes.Comment: 10 pages and 9 figure

Susceptibility to apoptosis is differentially regulated by c-myc and mutated Ha-ras oncogenes and is associated with endonuclease availability.

Oncogenes and oncosuppressors can deregulate cell replication in tumours, and recently have been shown to influence the probability of apoptosis. The effects of human c-myc and mutated (T24) Ha-ras oncogenes on susceptibility to apoptosis were investigated by introducing them into immortalised rat fibroblasts. The resulting family of transfectants showed closely similar measures of proliferation, but widely divergent rates of apoptosis, differing by up to fifteen-fold, that correlated inversely with population expansion rates in vitro. T24-ras transfectants with moderate or high p21ras expression showed reduced apoptosis, and this was reversed by pharmacological inhibition of membrane localisation of p21ras by mevinolin. In contrast, c-myc stimulated apoptosis, and this was further enhanced by serum deprivation. Inducibility of effector proteins represents one possible mechanism of genetic control of the susceptibility to apoptosis, and its investigation showed that c-myc was associated with expression by viable cells of latent calcium/magnesium sensitive endonuclease activity characteristic of apoptosis. In contrast, endonuclease activity was not detected in viable cells of a T24-ras transfectant expressing high levels of p21ras. Thus, there appeared to be differential regulation of susceptibility to apoptosis, positively by c-myc and negatively by activated ras, and this was associated with availability of endonuclease activity. Genetic modulation of apoptosis in human neoplasms is likely to influence net growth rate, retention of cells acquiring new mutations and response to certain chemotherapeutic agents