Ferruccio Ritossa’s scientific legacy 50 years after his discovery of the heat shock response: a new view of biology, a new society, and a new journal

The pioneering discovery of the heat shock response by the Italian scientist Ferruccio Ritossa reached maturity this year, 2012. It was 50 years ago that Professor Ritossa, through an extraordinary combination of serendipity, curiosity, knowledge and inspiration, published the first observation that cells could mount very strong transcriptional activity when exposed to elevated temperatures, which was coined the heat shock response. This discovery led to the identification of heat shock proteins, which impact many areas of current biology and medicine, and has created a new avenue for more exciting discoveries. In recognition of the discovery of the heat shock response, Cell Stress Society International (CSSI) awarded Professor Ritossa with the CSSI medallion in October 2010 in Dozza, Italy. This article is based on a session of the Fifth CSSI Congress held in Québec commemorating Professor Ritossa and his discovery

EC-SNe from super-AGB progenitors: theoretical models vs. observations

Using a parametric approach, we determine the configuration of super-AGB stars at the explosion as a function of the initial mass and metallicity, in order to verify if the EC-SN scenario involving a super-AGB star is compatible with the observations regarding SN2008ha and SN2008S. The results show that both the SNe can be explained in terms of EC-SNe from super-AGB progenitors having a different configuration at the collapse. The impact of these results on the interpretation of other sub-luminous SNe is also discussed.Comment: Accepted for publication in ApJ

The Possible White Dwarf-Neutron Star Connection

The current status of the problem of whether neutron stars can form, in close binary systems, by accretion-induced collapse (AIC) of white dwarfs is examined. We find that, in principle, both initially cold C+O white dwarfs in the high-mass tail of their mass distribution in binaries and O+Ne+Mg white dwarfs can produce neutron stars. Which fractions of neutron stars in different types of binaries (or descendants from binaries) might originate from this process remains uncertain.Comment: 6 pages. To appear in "White Dwarfs", ed. J. Isern, M. Hernanz, and E. Garcia-Berro (Dordrecht: Kluwer

Hsp21potentiates antifungal drug tolerance in Candida albicans

Peer reviewedPublisher PD

The Resolved Stellar Population of the Post-Starburst Galaxy NGC 1569

We present WFPC2-HST photometry (in the F439W and F555W bands) of the resolved stars in NGC 1569. The derived color-magnitude diagram (CMD) contains 2800 objects down to the 26th mag, and is complete down to the 23rd. Adopting the literature distance modulus and reddening, the CMD samples stars more massive than 4 Mo, corresponding to a look-back time of 0.15 Gyr approximately. The data are compared to synthetic CMDs to derive the recent star formation history in NGC 1569. It is found that the observed field has experienced a global burst of star formation (SF) lasting at least 0.1 Gyr, and ended a few Myr ago. During the burst, the SF rate was approximately constant, and, if quiescent periods occurred, they lasted less than 10 Myr. The level of the SF rate was very high: 0.5 Mo/yr for a Salpeter IMF, in stars with mass ranging from 0.1 to 120 Mo. When scaled for the surveyed area, the SF rate is approximately 100 times larger than found in the most active dwarf irregulars in the Local Group. The data are consistent with a Salpeter IMF, or slightly steeper exponents. We discuss the implications of our results in the general context of the evolution of dwarf galaxies.Comment: 63 pages including 2 tables and 12 figures, to be published in The Astrophysical Journa

Supernova rates from the Southern inTermediate Redshift ESO Supernova Search (STRESS)

To measure the supernova (SN) rates at intermediate redshift we performed the Southern inTermediate Redshift ESO Supernova Search (STRESS). Unlike most of the current high redshift SN searches, this survey was specifically designed to estimate the rate for both type Ia and core collapse (CC) SNe. We counted the SNe discovered in a selected galaxy sample measuring SN rate per unit blue band luminosity. Our analysis is based on a sample of ~43000 galaxies and on 25 spectroscopically confirmed SNe plus 64 selected SN candidates. Our approach is aimed at obtaining a direct comparison of the high redshift and local rates and at investigating the dependence of the rates on specific galaxy properties, most notably their colour. The type Ia SN rate, at mean redshift z=0.3, amounts to 0.22^{+0.10+0.16}_{-0.08 -0.14} h_{70}^2 SNu, while the CC SN rate, at z=0.21, is 0.82^{+0.31 +0.30}_{-0.24 -0.26} h_{70}^2 SNu. The quoted errors are the statistical and systematic uncertainties. With respect to local value, the CC SN rate at z=0.2 is higher by a factor of ~2 already at redshift, whereas the type Ia SN rate remains almost constant. This implies that a significant fraction of SN Ia progenitors has a lifetime longer than 2-3 Gyr. We also measured the SN rates in the red and blue galaxies and found that the SN Ia rate seems to be constant in galaxies of different colour, whereas the CC SN rate seems to peak in blue galaxies, as in the local Universe. SN rates per unit volume were found to be consistent with other measurements showing a steeper evolution with redshift for CC SNe with respect to SNe Ia. Finally we have exploited the link between star formation (SF) and SN rates to predict the evolutionary behaviour of the SN rates and compare it with the path indicated by observations.Comment: Accepted for publication in A&A; 25 pages (including on line material), 13 figure

Evolution of the number of accreting white dwarfs with shell nuclear burning and of occurrence rate of SN Ia

We analyze temporal evolution of the number of accreting white dwarfs with shell hydrogen burning in semidetached and detached binaries. We consider a stellar system in which star formation lasts for 10 Gyr with a constant rate, as well as a system in which the same amount of stars is formed in a single burst lasting for 1 Gyr. Evolution of the number of white dwarfs is confronted to the evolution of occurrence rate of events that usually are identified with SN Ia or accretion-induced collapses, i.e. with accumulation of Chandrasekhar mass by a white dwarf or a merger of a pair of CO white dwarfs with total mass not lower than the Chandrasekhar one. In the systems with a burst of star formation, at $t=$10 Gyr observed supersoft X-ray sources, most probably, are not precursors of SN Ia. The same is true for an overwhelming majority of the sources in the systems with constant star formation rate. In the systems of both kinds mergers of white dwarfs is the dominant SN Ia scenario. In symbiotic binaries, accreting CO-dwarfs do not accumulate enough mass for SN Ia explosion, while ONeMg-dwarfs finish their evolution by an accretion-induced collapse with formation of a neutron star.Comment: 11 pages, 2 figures, accepted by Astronomy Letter

Description of the Scenario Machine

We present here an updated description of the "Scenario Machine" code. This tool is used to carry out a population synthesis of binary stars. Previous version of the description can be found at http://xray.sai.msu.ru/~mystery//articles/review/contents.htmlComment: 32 pages, 3 figures. Corrected typo

Tune in to your emotions: a robust personalized affective music player

The emotional power of music is exploited in a personalized affective music player (AMP) that selects music for mood enhancement. A biosignal approach is used to measure listeners’ personal emotional reactions to their own music as input for affective user models. Regression and kernel density estimation are applied to model the physiological changes the music elicits. Using these models, personalized music selections based on an affective goal state can be made. The AMP was validated in real-world trials over the course of several weeks. Results show that our models can cope with noisy situations and handle large inter-individual differences in the music domain. The AMP augments music listening where its techniques enable automated affect guidance. Our approach provides valuable insights for affective computing and user modeling, for which the AMP is a suitable carrier application