Some Good Reasons to Use Matched Filters for the Detection of Point Sources in CMB Maps

In this draft we comment on the results concerning the performances of matched filters, scale adaptive filters and Mexican hat wavelet that recently appeared in literature in the context of point source detection in Cosmic Microwave Background maps. In particular, we show that, contrary to what has been claimed, the use of the matched filters still appear to be the most reliable and efficient method to disantangle point sources from the backgrounds, even when using detection criterion that, differently from the classic $n\sigma$ thresholding rule, takes into account not only the height of the peaks in the signal corresponding to the candidate sources but also their curvature.Comment: Replacement after submission to A&A and referee's comments. Astronomy and Astrophysics, in press, JNL/2003/473

Why did Supernova 1054 shine at late times?

The Crab nebula is the remnant of supernova 1054 (SN 1054). The progenitor of this supernova has, based on nucleosynthesis arguments, been modeled as an 8-10 solar mass star. Here we point out that the observations of the late light curve of SN 1054, from the historical records, are not compatible with the standard scenario, in which the late time emission is powered by the radioactive decay of small amounts of Ni-56. Based on model calculations we quantify this discrepancy. The rather large mass of Ni-56 needed to power the late time emission, 0.06[-0.03,+0.02] solar masses, seems inconsistent with abundances in the Crab nebula. The late light curve may well have been powered by the pulsar, which would make SN 1054 unique in this respect. Alternatively, the late light curve could have been powered by circumstellar interaction, in accordance with scenarios in which 8-10 solar mass stars are progenitors to `dense wind' supernovae.Comment: 5 pages, 2 figures. Accepted for publication in A&

Studies on the inheritance of resistance to crown gall disease of grapevine

Nearly 1800 seedlings of 27 hybrid families were screened for resistance to A. tumefaciens strain AT-1 belonging to biotype 3. The tested families included 12 crosses of sensitive and of resistant phenotypes, and 15 self-pollinated families both of sensitive and of resistant parents. Resistance originated from V. amurensis. The segregation ratio corresponded to 1 : 1 among the crosses and was 3 : 1 (resistant to sensitive) among the selfings of resistant parents. All seedlings from selved susceptible parents formed tumors. According to our results, a Mendelian dominant inheritance can be proposed for resistance to A. tumefaciens strain AT-1.Untersuchungen zur Vererbung der Mauke-Resistenz bei der RebeAnnähernd 1800 Genotypen aus 27 Kreuzungsfamilien wurden auf ihre Anfälligkeit gegen den Stamm AT-1 des Biotyps 3 von Agrobacterium tumefaciens geprüft. Die untersuchten Kreuzungsfamilien umfaßten 12 Kreuzungskombinationen resistenter und anfälliger Phänotypen und 15 Selbstungen resistenter und anfälliger Eltern. Die Quelle der Mauke-Resistenz ist Vitis amurensis. Das Aufspaltungsverhältnis zwischen resistenten und anfälligen Sämlingen beträgt bei Fremdbefruchtung 1 : 1 und bei Selbstung der resistenten Eltern 3 : 1; bei Selbstung der anfälligen Eltern bildete jeder Sämling Tumoren aus. Aufgrund der Ergebnisse kann eine dominante Vererbung der Resistenz gegen A. tumefaciens AT-1 angenommen werden

Inheritance of isoenzymes and soluble proteins in grape varieties and F1 hybrids

The aim or our experiments was to verify the existence of a genetically interpretable molecular polymorphism in several grape varieties and their F1 hybrids, which we can employ for genetical and ampelographical characterization. In addition, we also programmed the progress of investigation methods. The authors present protein and enzyme analysis of two pairs of parents, Pearl of Csaba x S. V. 12375 and Saperavi x Blaufrankisch, and of ten other cultivars and several F1 progenies. The best experimental results for genetic markers can be gained when shoot and callus samples are collected at the end of winter, in February, at the same time. Spring shoot collection is less effective because of high chlorophyll contents, and must and wine samples are less suitable due to their microbial contamination. The esterase enzyme group gives well reproducible, characteristically differentiated patterns. The enzyme patterns of parental varieties typically segregate in individual progenies, hence they prove to be good markers

Genetic diversity among twelve grape cultivars indigenous to the Carpathian Basin revealed by RAPD markers

Twelve cultivars (Vitis vinifera L.) were subjected to RAPD analysis in order to estimate the genetic diversity among these genotypes and to analyse their genetic relationships. The study was performed using 28 primers that generated 120 polymorphic fragments. There was genetic variation among the cultivars with values of genetic diversity ranging from 0.419 to 0.642 using the Jaccard coefficient. UPGMA analysis of distance matrix resulted in a dendrogram with three clusters. The dendrogram shows that the cultivars of our study can be distinguished to a relatively high degree. Results were compared with the taxonomic classification and with the synonyms of the cultivars. The RAPD technique was useful for identification and discrimination of these grape cultivars

No trace of a single-degenerate companion in late spectra of SNe 2011fe and 2014J

Left-over, ablated material from a possible non-degenerate companion can reveal itself after about one year in spectra of Type Ia SNe (SNe Ia). We have searched for such material in spectra of SN 2011fe (at 294 days after the explosion) and for SN 2014J (315 days past explosion). The observations are compared with numerical models simulating the expected line emission. The spectral lines sought for are H-alpha, [O I] 6300 and [Ca II] 7291,7324, and the expected width of these lines is about 1000 km/s. No signs of these lines can be traced in any of the two supernovae. When systematic uncertainties are included, the limits on hydrogen-rich ablated gas in SNe 2011fe and 2014J are 0.003 M_sun and 0.0085 M_sun, respectively, where the limit for SN 2014J is the second lowest ever, and the limit for SN 2011fe is a revision of a previous limit. Limits are also put on helium-rich ablated gas. These limits are used, in conjunction with other data, to argue that these supernovae can stem from double-degenerate systems, or from single-degenerate systems with a spun up/spun down super-Chandrasekhar white dwarf. For SN 2011fe, other types of hydrogen-rich donors can likely be ruled out, whereas for SN 2014J a main-sequence donor system with large intrinsic separation is still possible. Helium-rich donor systems cannot be ruled out for any of the two supernovae, but the expected short delay time for such progenitors makes this possibility less likely, especially for SN 2011fe. The broad [Ni II] 7378 emission in SN 2014J is redshifted by about +1300 km/s, as opposed to the known blueshift of roughly -1100 km/s for SN 2011fe. [Fe II] 7155 is also redshifted in SN 2014J. SN 2014J belongs to a minority of SNe Ia that both have a nebular redshift of [Fe II] 7155 and [Ni II] 7378, and a slow decline of the Si II 6355 absorption trough just after B-band maximum.Comment: 13 pages, submitted to A&

Consensus formation on coevolving networks: groups' formation and structure

We study the effect of adaptivity on a social model of opinion dynamics and consensus formation. We analyze how the adaptivity of the network of contacts between agents to the underlying social dynamics affects the size and topological properties of groups and the convergence time to the stable final state. We find that, while on static networks these properties are determined by percolation phenomena, on adaptive networks the rewiring process leads to different behaviors: Adaptive rewiring fosters group formation by enhancing communication between agents of similar opinion, though it also makes possible the division of clusters. We show how the convergence time is determined by the characteristic time of link rearrangement. We finally investigate how the adaptivity yields nontrivial correlations between the internal topology and the size of the groups of agreeing agents.Comment: 10 pages, 3 figures,to appear in a special proceedings issue of J. Phys. A covering the "Complex Networks: from Biology to Information Technology" conference (Pula, Italy, 2007