Planetary nebulae, tracers of stellar nucleosynthesis

We review the information that planetary nebulae and their immediate progenitors, the post-AGB objects, can provide to probe the nucleosynthesis and mixing in low and intermediate mass stars. We emphasize new approaches based on high signal-to-noise spectroscopy of planetary nebulae and of their central stars. We mention some of the problems still to overcome. We emphasize that, as found by several authors, planetary nebulae in low metallicity environments cannot be used to probe the oxygen abundance in the interstellar medium out of which their progenitors were formed, because of abundance modification during stellar evolution.Comment: 13 pages, to appear in "StellarNucleosynthesis: 50yearsafterB2FH", eds. C. Charbonnel and J.-P. Zahn, EAS PublicationsSerie

Hartmann's procedure versus sigmoidectomy with primary anastomosis for perforated diverticulitis with purulent or fecal peritonitis:Three-year follow-up of a randomised controlled trial

Background: The aim of the present study is to present the three years follow-up a randomised controlled trial that compared Hartmann's Procedure (HP) with sigmoidectomy with primary anastomosis (with or without defunctioning ileostomy) (PA) in a randomised design to determine the optimal treatment strategy for perforated diverticulitis with purulent or fecal peritonitis. Methods: Data were prospectively gathered for the first 12 months after randomization and retrospectively collected up to 36 months. The primary long-term endpoint was stoma free rate 36 months after the index procedure. Secondary outcomes were patients with a stoma at 36 months, percentage of stoma reversals, related reinterventions, parastomal/incisional hernia rates, total in hospital days including all readmissions regardless their relation to the intervention, overall morbidity and mortality. Results: Three years follow-up was completed in 119 of the originally 130 included patients, with 57 (48%) in the PA-group and 62 (52%) patients in the HP-group. 36 months stoma free rate was significantly better for patients undergoing PA compared with HP (PA 92% vs HP 81%, hazard ratio 2.326 [95% CI 1.538–3.517]; log-rank p < 0·0001). Stoma reversal rates did not significantly differ (PA 31/40(78%) versus HP 45/61(74%), p = 0.814). Overall cumulative morbidity (PA 21/57(36%) versus HP 30/62(48%), p = 0.266) and mortality (PA 6/57(11%) versus HP 7/62 (11%), p = 1.000) did not differ between groups. However, more parastomal hernias occurred in the HP-group (HP 10/62(16%) vs PA 1/57(2%), p = 0.009) and the mean total in hospital days after three years follow-up was significantly lower in the PA-group compared to the HP-group (PA 14 days (IQR 9.5–22.5) versus HP 17 days (IQR 12.5–27.5)), p = 0.025). Conclusion: Long-term results showed that in haemodynamically stable, immunocompetent patients primary anastomosis is superior to Hartmann's procedure as treatment for perforated diverticulitis with respect to long-term stoma free rate, overall hospitalization and parastomal hernias

Laparoscopic peritoneal lavage versus sigmoidectomy for perforated diverticulitis with purulent peritonitis:three-year follow-up of the randomised LOLA trial

Background : This study aimed to compare laparoscopic lavage and sigmoidectomy as treatment for perforated diverticulitis with purulent peritonitis during a 36 month follow-up of the LOLA trial. Methods : Within the LOLA arm of the international, multicentre LADIES trial, patients with perforated diverticulitis with purulent peritonitis were randomised between laparoscopic lavage and sigmoidectomy. Outcomes were collected up to 36 months. The primary outcome of the present study was cumulative morbidity and mortality. Secondary outcomes included reoperations (including stoma reversals), stoma rates, and sigmoidectomy rates in the lavage group. Results : Long-term follow-up was recorded in 77 of the 88 originally included patients, 39 were randomised to sigmoidectomy (51%) and 38 to laparoscopic lavage (49%). After 36 months, overall cumulative morbidity (sigmoidectomy 28/39 (72%) versus lavage 32/38 (84%), p = 0·272) and mortality (sigmoidectomy 7/39 (18%) versus lavage 6/38 (16%), p = 1·000) did not differ. The number of patients who underwent a reoperation was significantly lower for lavage compared to sigmoidectomy (sigmoidectomy 27/39 (69%) versus lavage 17/38 (45%), p = 0·039). After 36 months, patients alive with stoma in situ was lower in the lavage group (proportion calculated from the Kaplan–Meier life table, sigmoidectomy 17% vs lavage 11%, log-rank p = 0·0268). Eventually, 17 of 38 (45%) patients allocated to lavage underwent sigmoidectomy. Conclusion : Long-term outcomes showed that laparoscopic lavage was associated with less patients who underwent reoperations and lower stoma rates in patients alive after 36 months compared to sigmoidectomy. No differences were found in terms of cumulative morbidity or mortality. Patient selection should be improved to reduce risk for short-term complications after which lavage could still be a valuable treatment option. Graphical abstract: [Figure not available: see fulltext.

Galactic planetary nebulae with Wolf-Rayet nuclei. II. A consistent observational data set

We present high resolution spectrophotometric data for 34 galactic planetary nebulae with [WC] nuclei (WRPNe).The sample includes PNe with early and late [WC] stars and some WELS. Physical conditions and chemical abundances have been derived and expansion velocities were estimated for most objects of the sample. A statistical study was developed to find fundamental relationships between the nebular and central star parameters.We found evidence for a strong unexpected electron temperature gradient in WRPNe which is related to nebular excitation. Abundance ratios indicate that there seems to be no preferential stellar mass for the WR phenomenon to occur in the nucleus of a planetary nebula. The PNe M 1-25 and M 1-32 were found to have very small Ne/O ratios.Our data confirm the trend of the electron density decreasing with decreasing spectral type, which was interpreted as evidence that [WC] stars evolve from late to early [WC] types. On the other hand, the expansion velocities do not show the increase with decreasing spectral type, that one might expect in such a scenario. Two objects with very late [WC] central stars, K 2-16 and PM 1-188, do not follow the general density sequence, being of very low density for their spectral types. We suggest that the stars either underwent a late helium flash (the ``born again'' scenario) or that they have had a particularly slow evolution from the AGB. The 6 WELS of our sample follow the same density vs. [WC]-type relation as the bona fide WRPNe, but they tend to have smaller expansion velocities. The comparison between the WRPNe in the Magellanic Clouds and in the Galaxy indicates that metallicity affects the [WR] phenomenon in central stars of planetary nebulae.Comment: 20 pages, including 2 figures and 3 tables. Paper accepted in Astronomy and Astrophysics, 200

The effect of feedback on the emission properties of the Warm-Hot Intergalactic Medium

At present, 30-40 per cent of the baryons in the local Universe is still undetected. According to theoretical predictions, this gas should reside in filaments filling the large-scale structure (LSS) in the form of a Warm-Hot Intergalactic Medium (WHIM), at temperatures of 10^5 - 10^7 K, thus emitting in the soft X-ray energies via free-free interaction and line emission from heavy elements. In this work we characterize the properties of the X-ray emission of the WHIM, and the LSS in general, focusing on the influence of different physical mechanisms, namely galactic winds (GWs), black-hole feedback and star-formation, and providing estimates of possible observational constraints. To this purpose we use a set of cosmological hydrodynamical simulations that include a self-consistent treatment of star-formation and chemical enrichment of the intergalactic medium, that allows us to follow the evolution of different metal species. We construct a set of simulated light-cones to make predictions of the emission in the 0.3-10 keV energy range. We obtain that GWs increase by a factor of 2 the emission of both galaxy clusters and WHIM. The amount of oxygen at average temperature and, consequently, the amount of expected bright Ovii and Oviii lines is increased by a factor of 3 due to GWs and by 20 per cent when assuming a top-heavy IMF. We compare our results with current observational constraints and find that the emission from faint groups and WHIM should account from half to all of the unresolved X-ray background in the 1-2 keV band.Comment: 15 pages, 8 figures, 4 tables. Accepted for publication in the MNRAS. Minor changes after referee repor

The chemical enrichment of the ICM from hydrodynamical simulations

The study of the metal enrichment of the intra-cluster and inter-galactic media (ICM and IGM) represents a direct means to reconstruct the past history of star formation, the role of feedback processes and the gas-dynamical processes which determine the evolution of the cosmic baryons. In this paper we review the approaches that have been followed so far to model the enrichment of the ICM in a cosmological context. While our presentation will be focused on the role played by hydrodynamical simulations, we will also discuss other approaches based on semi-analytical models of galaxy formation, also critically discussing pros and cons of the different methods. We will first review the concept of the model of chemical evolution to be implemented in any chemo-dynamical description. We will emphasise how the predictions of this model critically depend on the choice of the stellar initial mass function, on the stellar life-times and on the stellar yields. We will then overview the comparisons presented so far between X-ray observations of the ICM enrichment and model predictions. We will show how the most recent chemo-dynamical models are able to capture the basic features of the observed metal content of the ICM and its evolution. We will conclude by highlighting the open questions in this study and the direction of improvements for cosmological chemo-dynamical models of the next generation.Comment: 25 pages, 11 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 18; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke

Metal enrichment processes

There are many processes that can transport gas from the galaxies to their environment and enrich the environment in this way with metals. These metal enrichment processes have a large influence on the evolution of both the galaxies and their environment. Various processes can contribute to the gas transfer: ram-pressure stripping, galactic winds, AGN outflows, galaxy-galaxy interactions and others. We review their observational evidence, corresponding simulations, their efficiencies, and their time scales as far as they are known to date. It seems that all processes can contribute to the enrichment. There is not a single process that always dominates the enrichment, because the efficiencies of the processes vary strongly with galaxy and environmental properties.Comment: 18 pages, 8 figures, accepted for publication in Space Science Reviews, special issue "Clusters of galaxies: beyond the thermal view", Editor J.S. Kaastra, Chapter 17; work done by an international team at the International Space Science Institute (ISSI), Bern, organised by J.S. Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke

Cellular and Mitochondrial Effects of Alcohol Consumption

Alcohol dependence is correlated with a wide spectrum of medical, psychological, behavioral, and social problems. Acute alcohol abuse causes damage to and functional impairment of several organs affecting protein, carbohydrate, and fat metabolism. Mitochondria participate with the conversion of acetaldehyde into acetate and the generation of increased amounts of NADH. Prenatal exposure to ethanol during fetal development induces a wide spectrum of adverse effects in offspring, such as neurologic abnormalities and pre- and post-natal growth retardation. Antioxidant effects have been described due to that alcoholic beverages contain different compounds, such as polyphenols as well as resveratrol. This review analyzes diverse topics on the alcohol consumption effects in several human organs and demonstrates the direct participation of mitochondria as potential target of compounds that can be used to prevent therapies for alcohol abusers

Climate Change Impacts on Groundwater and Dependent Ecosystems - in press

[EN] Aquifers and groundwater-dependent ecosystems (GDEs) are facing increasing pressure from water consumption, irrigation and climate change. These pressures modify groundwater levels and their temporal patterns and threaten vital ecosystem services such as arable land irrigation and ecosystem water requirements, especially during droughts. This review examines climate change effects on groundwater and dependent ecosystems. The mechanisms affecting natural variability in the global climate and the consequences of climate and land use changes due to anthropogenic influences are summarised based on studies from different hydrogeological strata and climate zones. The impacts on ecosystems are discussed based on current findings on factors influencing the biodiversity and functioning of aquatic and terrestrial ecosystems. The influence of changes to groundwater on GDE biodiversity and future threats posed by climate change is reviewed, using information mainly from surface water studies and knowledge of aquifer and groundwater ecosystems. Several gaps in research are identified. Due to lack of understanding of several key processes, the uncertainty associated with management techniques such as numerical modelling is high. The possibilities and roles of new methodologies such as indicators and modelling methods are discussed in the context of integrated groundwater resources management. Examples are provided of management impacts on groundwater, with recommendations on sustainable management of groundwaterThe preparation of this review was partly funded by EC 7th framework Project GENESIS (Contract Number 226536).Klove, B.; Ala-Aho, P.; Bertrand, G.; Gurdak, JJ.; Kupfersberger, H.; Kværner, J.; Muotka, T.... (2014). Climate Change Impacts on Groundwater and Dependent Ecosystems - in press. Journal of Hydrology. 518(Part B):250-266. https://doi.org/10.1016/j.jhydrol.2013.06.037S250266518Part