Synthetic spectra of H Balmer and HeI absorption lines. II: Evolutionary synthesis models for starburst and post-starburst galaxies

We present evolutionary stellar population synthesis models to predict the spectrum of a single-metallicity stellar population, with a spectral sampling of 0.3 A in five spectral regions between 3700 and 5000 A. The models, which are optimized for galaxies with active star formation, synthesize the profiles of the hydrogen Balmer series (Hb, Hg, Hd, H8, H9, H10, H11, H12 and H13) and the neutral helium absorption lines (HeI 4922, HeI 4471, HeI 4388, HeI 4144, HeI 4121, HeI 4026, HeI 4009 and HeI 3819) for a burst with an age ranging from 1 to 1000 Myr, and different assumptions about the stellar initial mass function. Continuous star formation models lasting for 1 Gyr are also presented. The input stellar library includes NLTE absorption profiles for stars hotter than 25000 K and LTE profiles for lower temperatures. The temperature and gravity coverage is 4000 K <Teff< 50000 K and 0.0< log g$< 5.0, respectively. The models can be used to date starburst and post-starburst galaxies until 1 Gyr. They have been tested on data for clusters in the LMC, the super-star cluster B in the starburst galaxy NGC 1569, the nucleus of the dwarf elliptical NGC 205 and a luminous "E+A" galaxy. The full data set is available for retrieval at http://www.iaa.es/ae/e2.html and at http://www.stsci.edu/science/starburst/, or on request from the authors at [email protected]: To be published in ApJS. 48 pages and 20 figure

Synthetic spectra of H Balmer and HeI absorption lines. I: Stellar library

We present a grid of synthetic profiles of stellar H Balmer and HeI lines at optical wavelengths with a sampling of 0.3 A. The grid spans a range of effective temperature 4000 K < Teff < 50000 K, and gravity 0.0 < log g < 5.0 at solar metallicity. For Teff > 25000 K, NLTE stellar atmosphere models are computed using the code TLUSTY (Hubeny 1988). For cooler stars, Kurucz (1993) LTE models are used to compute thesynthetic spectra. The grid includes the profiles of the high-order hydrogen Balmer series and HeI lines for effective temperatures and gravities that have not been previously synthesized. The behavior of H8 to H13 and HeI 3819 with effective temperature and gravity is very similar to that of the lower terms of the series (e.g. Hb) and the other HeI lines at longer wavelengths; therefore, they are suited for the determination of the atmospheric parameters of stars. These lines are potentially important to make predictions for these stellar absorption features in galaxies with active star formation. Evolutionary synthesis models of these lines for starburst and post-starburst galaxies are presented in a companion paper. The full set of the synthetic stellar spectra is available for retrieval at our website http://www.iaa.es/ae/e2.html and http://www.stsci.edu/science/starburst/ or on request from the authors at [email protected]: To be published in ApJS. 28 pages and 12 figure

Spectrophotometric investigations of Blue Compact Dwarf Galaxies: Markarian 35

We present results from a detailed spectrophotometric analysis of the blue compact dwarf galaxy Mrk 35 (Haro 3), based on deep optical (B,V,R,I) and near-IR (J,H,K) imaging, Halpha narrow-band observations and long-slit spectroscopy. The optical emission of the galaxy is dominated by a central young starburst, with a bar-like shape, while an underlying component of stars, with elliptical isophotes and red colors, extends more than 4 kpc from the galaxy center. High resolution Halpha and color maps allow us to identify the star-forming regions, to spatially discriminate them from the older stars, and to recognize several dust patches. We derive colors and Halpha parameters for all the identified star-forming knots. Observables derived for each knot are corrected for the contribution of the underlying older stellar population, the contribution by emission lines, and from interstellar extinction, and compared with evolutionary synthesis models. We find that the contributions of these three factors are by no means negligible and that they significantly vary across the galaxy. Therefore, careful quantification and subtraction of emission lines, galaxy host contribution, and interstellar reddening at every galaxy position, are essential to derive the properties of the young stars in BCDs. We find that we can reproduce the colors of all the knots with an instantaneous burst of star formation and the Salpeter initial mass function with an upper mass limit of 100 M_solar. In all cases the knots are just a few Myr old. The underlying population of stars has colors consistent with being several Gyr old.Comment: 21 pages, 13 figures. Accepted for publication in ApJ, tentatively scheduled for the ApJ November 1, 2007 v669n1 issu

Spectrophotometric Observations of Blue Compact Dwarf Galaxies: Mrk 370

We present results from a detailed spectrophotometric analysis of the blue compact dwarf galaxy (BCD) Mrk 370, based on deep UBVRI broad-band and Halpha narrow-band observations, and long-slit and two-dimensional spectroscopy of its brightest knots. The spectroscopic data are used to derive the internal extinction, and to compute metallicities, electronic density and temperature in the knots. By subtracting the contribution of the underlying older stellar population, modeled by an exponential function, removing the contribution from emission lines, and correcting for extinction, we can measure the true colors of the young star-forming knots. We show that the colors obtained this way differ significantly from those derived without the above corrections, and lead to different estimates of the ages and star-forming history of the knots. Using predictions of evolutionary synthesis models, we estimate the ages of both the starburst regions and the underlying stellar component. We found that we can reproduce the colors of all the knots with an instantaneous burst of star formation and the Salpeter initial mass function with an upper mass limit of 100 solar masses. The resulting ages range between 3 and 6 Myrs. The colors of the low surface brightness component are consistent with ages larger than 5 Gyr. The kinematic results suggest ordered motion around the major axis of the galaxy.Comment: 26 pages with 14 figures; accepted for publication in Ap

Enteric Neurospheres Are Not Specific to Neural Crest Cultures: Implications for Neural Stem Cell Therapies

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited

Translation, Identity, Society: The European Case of Cultural Multiplicity

The article discusses the philosophy of the translation of Domenico Jervolino applying it to the case of the European Union. The models of multi-culturalism and interculture are implemented within the EU

Active or passive? A multi-marker approach to compare active and passive eDNA sampling in riverine environments

: Environmental DNA (eDNA) is increasingly used in biodiversity monitoring with several collection techniques proposed. Those applied to aquatic eDNA can now be divided into two categories: active and passive sampling. Active sampling involves the deliberate and controlled collection of environmental samples, and the most common method is water filtration. Passive sampling is a more recent technique that involves capturing eDNA by relying on its adsorption to samplers, which can be fabricated from various materials, and submerged for minutes, hours or weeks. In this study, we compared the performance of water filtration and Passive eDNA Sampling (PEDS) with granular active carbon in terms of detected taxa collected from four different sites of the same river system. eDNA samples were amplified for three molecular markers for 18S rRNA, 12S rRNA and COI genes, with primers according to the literature that target invertebrates and vertebrates. The study revealed that PEDS detected on average more species in 18S rRNA and 12S rRNA assays, with 18S rRNA results presenting a significantly higher homogeneity of read variances between samples. Biological communities captured differed between PEDS and filters. The former method retrieved a significant number of microinvertebrates and chironomids (Chironomidae, Diptera), detecting a similar number of vertebrates to filters, but with lower performance in the detection of fish. Notably, both methods performed well with amphibians, successfully identifying all species linked to lotic environments in the studied area. Compared to PEDS, the eDNA capture protocol using filters yielded more sequences identified as ephemeropterans, trichopterans, and acarines. In addition, PEDS was more cost-effective and environmentally sustainable. These findings imply that there is no definitive superior eDNA sampling method. Consequently, in conjunction with studies proposing new methods of eDNA sampling, studies comparing their performance with a broad taxonomic representation will be pivotal

Prognostic value of innate and adaptive immunity in cancers

Cancer remains one of the most complex diseases affecting humans and, despite the impressive advances that have been made in molecular and cell biology, how cancer cells progress and acquire their metastatic ability still remains debated. Tumors are heterogeneous cellular systems whose growth depends on dynamical interactions among the cancer cells, and between cells and the constantly changing microenvironment. Several types of immune cells, including cells of both the innate and adaptive immune system, are comprised in the microenvironment of human cancers. While chronic inflammation is considered as one of the hallmarks of cancer being associated to increased risk of tumor development and progression, the clinical relevance of innate and adaptive cellular components of the immune system is still today less clear. A relevant issue is to unravel the discrepancy between the inhibitory effects on cancer growth exerted by the local immune response and the promoting effects on cancer proliferation, invasion, and dissemination induced by some types of inflammatory cells. Here, we discuss the actual knowledge on the role played by innate and adaptive immune system in the local progression and metastasis of human cancer of unrelated histological origin and the prognostic information that we can currently understand and exploit

Adoption of a Newly Introduced Dermal Matrix: Preliminary Experience and Future Directions

Introduction. Acellular dermal matrix (ADM) products are adopted in the management of injuries to soft tissues. ADMs have been increasingly employed for their clinical advantages, and they are acquiring relevance in the future of plastic surgery. The aim of our study is to evaluate the application of ADMs in our patients who could not undergo fast reconstruction. Materials and Methods. We performed a retrospective study on 12 patients who underwent ADM placement for scalp and limb surgical reconstructions at the Humanitas Research Hospital, Rozzano (Milano), Italy. Wounds resulted from 9 tumor resections and 3 chronic ulcers. The ADM substrate used to treat these lesions was PELNACTM (Gunze, Japan), a double-layered matrix composed of atelocollagen porcine tendon and silicon reinforcement. All patients underwent a second surgical operation to complete the treatment with a full-thickness skin graft to cover the lesion. Results. In this study, 12 patients were treated with PELNACTM: 11 out of 12 patients showed a good attachment over a median time of 21.3 days (range 14-27). After almost 23 days, all patients were ready to undergo a full-thickness skin grafting. Conclusion. This study assesses the benefits of PELNACTM and proposes this method as an alternative to traditional approaches, especially in situations where the latter techniques cannot be applied