Confirmation of circumstellar phosphine

Phosphine (PH3) was tentatively identified a few years ago in the carbon star envelopes IRC+10216 and CRL2688 from observations of an emission line at 266.9 GHz attributable to the J=1-0 rotational transition. We report the detection of the J=2-1 rotational transition of PH3 in IRC+10216 using the HIFI instrument on board Herschel, which definitively confirms the identification of PH3. Radiative transfer calculations indicate that infrared pumping to excited vibrational states plays an important role in the excitation of PH3 in the envelope of IRC+10216, and that the observed lines are consistent with phosphine being formed anywhere between the star and 100 R* from the star, with an abundance of 1e-8 relative to H2. The detection of PH3 challenges chemical models, none of which offers a satisfactory formation scenario. Although PH3 locks just 2 % of the total available phosphorus in IRC+10216, it is together with HCP, one of the major gas phase carriers of phosphorus in the inner circumstellar layers, suggesting that it could be also an important phosphorus species in other astronomical environments. This is the first unambiguous detection of PH3 outside the solar system, and a further step towards a better understanding of the chemistry of phosphorus in space.Comment: Accepted for publication in ApJ Letter

Robles y hayas en España. Conservación de recursos genéticos

Spain is an active member in EUFORGEN Social Broadleaves Network since 1999. This network includes Beech and European white oaks. Quercus spp includes a complex of species intimately related geneticaly and ecologicaly. It therefore reveals the Iberic Peninsula, together with F. sylvatica, as an interesting emplacement with a high genetic potential sharing the species nemoral and mediterranean climate. In this paper a revision of the conservation state of the forest genetic resources of oaks and beech is presented. The problematic of these species is also studied as well as an evaluation of the works already done towards this area in order to be able to define a conservation program of the genetic resources. Actually we have available information about geographic variation of the species across the delimitation of regions of provenance and regions of identification and use. The filogenetic relationship studied through chloroplast DNA reveals 2 European lineages for Beech and various lineages from inside and outside the Iberian Peninsula for Oaks, indicating furthermore a strong relationship within it. The structure of the genetic diversity is partially known for Beech showing a clear geographic trend. There are several provenance tests for Beech, an evaluation of which is essential to learn about the behavior of our genetic material and to be able to make recommendations for the use of the species. When Oaks are considered the situation is more precarious and studies aiming the knowledge of genetic variation must be reinforced.Las visibles consecuencias de la fuerte influencia antrópica que directamente sufren y han sufrido nuestros bosques obliga a la integración de científicos de distintas disciplinas, gestores de los montes, políticos y a la sociedad en general, para aunar esfuerzos dirigidos a la conservación de nuestros recursos genéticos forestales. La Estrategia Forestal Española constituye actualmente el marco administrativo para diseñar y llevar a cabo los programas de conservación. España toma parte activa en el grupo de trabajo sobre robles y hayas EUFORGEN Social Broadleaves desde 1999. El grupo incluye a las hayas y los robles blancos europeos. En el programa español se hace necesaria la consideración de las siguientes especies: Fagus sylvatica, Quercus robur, Q. petraea, Q. humilis, Q. pyrenaica, Q. faginea, Q. canariensis y Q. lusitanica. El género Quercus forma un complejo de especies estrechamente relacionadas ecológica y genéticamente, presentando en la Península Ibérica, junto a F. sylvatica, una situación interesante y con alto potencial genético por ser especies que comparten los climas nemoral con el mediterráneo. En el presente trabajo se hace una revisión del estado de conservación de los recursos genéticos forestales de robles y hayas y de la problemática que presentan estas especies, y se hace una evaluación de los trabajos realizados ya en este sentido, para poder definir un programa de conservación de sus recursos genéticos. Actualmente contamos con importante información sobre la variación geográfica de las especies a través de la delimitación de las regiones de procedencia y de las regiones de identificación y uso. La relación filogenética estudiada a través del ADN de cloroplastos indica dos linajes para el haya procedentes de Europa y varios linajes para el conjunto de los robles con origen dentro y fuera de la Península Ibérica, indicando además un fuerte parentesco dentro del grupo. La estructuración de la diversidad genética se conoce parcialmente para el haya, mostrando una agrupación geográfica clara. En la actualidad existen ensayos de procedencia de haya, cuya periódica evaluación se hace imprescindible para el conocimiento del comportamiento de nuestro material genético y poder así hacer recomendaciones de uso de la especie. En el caso de los robles, la situación es más precaria, debiendo apoyar el inicio de estudios genéticos cuyo objetivo sea el conocimiento de la variabilidad genética, tanto con marcadores genéticos como con ensayos de comportamiento de las procedencias

Reaction Networks For Interstellar Chemical Modelling: Improvements and Challenges

We survey the current situation regarding chemical modelling of the synthesis of molecules in the interstellar medium. The present state of knowledge concerning the rate coefficients and their uncertainties for the major gas-phase processes -- ion-neutral reactions, neutral-neutral reactions, radiative association, and dissociative recombination -- is reviewed. Emphasis is placed on those reactions that have been identified, by sensitivity analyses, as 'crucial' in determining the predicted abundances of the species observed in the interstellar medium. These sensitivity analyses have been carried out for gas-phase models of three representative, molecule-rich, astronomical sources: the cold dense molecular clouds TMC-1 and L134N, and the expanding circumstellar envelope IRC +10216. Our review has led to the proposal of new values and uncertainties for the rate coefficients of many of the key reactions. The impact of these new data on the predicted abundances in TMC-1 and L134N is reported. Interstellar dust particles also influence the observed abundances of molecules in the interstellar medium. Their role is included in gas-grain, as distinct from gas-phase only, models. We review the methods for incorporating both accretion onto, and reactions on, the surfaces of grains in such models, as well as describing some recent experimental efforts to simulate and examine relevant processes in the laboratory. These efforts include experiments on the surface-catalysed recombination of hydrogen atoms, on chemical processing on and in the ices that are known to exist on the surface of interstellar grains, and on desorption processes, which may enable species formed on grains to return to the gas-phase.Comment: Accepted for publication in Space Science Review

Discovery of the propargyl radical (CH2CCH) in TMC-1: one of the most abundant radicals ever found and a key species for cyclization to benzene in cold dark clouds

We present the first identification in interstellar space of the propargyl radical (CH2CCH). This species was observed in the cold dark cloud TMC-1 using the Yebes 40m telescope. The six strongest hyperfine components of the 2,0,2-1,0,1 rotational transition, lying at 37.46~GHz, were detected with signal-to-noise ratios in the range 4.6-12.3 sigma. We derive a column density of 8.7e13 cm-2 for CH2CCH, which translates to a fractional abundance relative to H2 of 8.7e-9. This radical has a similar abundance to methyl acetylene, with an abundance ratio CH2CCH/CH3CCH close to one. The propargyl radical is thus one of the most abundant radicals detected in TMC-1, and it is probably the most abundant organic radical with a certain chemical complexity ever found in a cold dark cloud. We constructed a gas-phase chemical model and find calculated abundances that agree with, or fall two orders of magnitude below, the observed value depending on the poorly constrained low-temperature reactivity of CH2CCH with neutral atoms. According to the chemical model, the propargyl radical is essentially formed by the C + C2H4 reaction and by the dissociative recombination of C3Hn+ ions with n = 4-6. The propargyl radical is believed to control the synthesis of the first aromatic ring in combustion processes, and it probably plays a key role in the synthesis of large organic molecules and cyclization processes to benzene in cold dark clouds.Comment: Accepted for publication in A&A Letter

Constraints on the H2O formation mechanism in the wind of carbon-rich AGB stars

Context. The recent detection of warm H$_2$O vapor emission from the outflows of carbon-rich asymptotic giant branch (AGB) stars challenges the current understanding of circumstellar chemistry. Two mechanisms have been invoked to explain warm H$_2$O vapor formation. In the first, periodic shocks passing through the medium immediately above the stellar surface lead to H$_2$O formation. In the second, penetration of ultraviolet interstellar radiation through a clumpy circumstellar medium leads to the formation of H$_2$O molecules in the intermediate wind. Aims. We aim to determine the properties of H$_2$O emission for a sample of 18 carbon-rich AGB stars and subsequently constrain which of the above mechanisms provides the most likely warm H$_2$O formation pathway. Methods, Results, and Conclusions. See paper

Time Variability of Molecular Line Emission in IRC+10216

We present the results of monitoring the molecular emission of the C-rich AGB star IRC+10216 over 3 years with the Herschel Space Observatory. Observations of rotational transitions of various vibrational levels of CO, 13CO, CS, CCH, H2O, SiO, SiS, SiC2, HCN and HNC have been collected with the HIFI, PACS and SPIRE instruments over multiple epochs. The intensity monitoring shows strong and periodic variations of most of the observed molecules, often with differential behavior depending on the transition level (larger variation at higher J), and generally enhanced modulations in the vibrational modes of some of these molecules (e.g. HCN). These results show that the effect of IR pumping through the different vibrational levels on the emergent line profiles of a given transition can be really significant. This implies that the IR radiation field of the circumstellar envelope and its time variation has to be taken into account in any radiative transfer model in order to derive accurately the physico-chemical structure of the envelope

Strong CH+ J=1-0 emission and absorption in DR21

We report the first detection of the ground-state rotational transition of the methylidyne cation CH+ towards the massive star-forming region DR21 with the HIFI instrument onboard the Herschel satellite. The line profile exhibits a broad emission line, in addition to two deep and broad absorption features associated with the DR21 molecular ridge and foreground gas. These observations allow us to determine a CH+ J=1-0 line frequency of 835137 +/- 3 MHz, in good agreement with a recent experimental determination. We estimate the CH+ column density to be a few 1e13 cm^-2 in the gas seen in emission, and > 1e14 cm^-2 in the components responsible for the absorption, which is indicative of a high line of sight average abundance [CH+]/[H] > 1.2x10^-8. We show that the CH+ column densities agree well with the predictions of state-of-the-art C-shock models in dense UV-illuminated gas for the emission line, and with those of turbulent dissipation models in diffuse gas for the absorption lines.Comment: Accepted for publication in A&

Genetic variability of histamine receptors in patients with Parkinson's disease

<p>Abstract</p> <p>Background</p> <p>Changes in the density and expression of histamine receptors (HRH) have been detected in Parkinson's disease (PD) patients, and HRH antagonists bring about improvements in motor and other symptoms, thus suggesting that HRH play a role in the clinical response of PD patients. This study is aimed to analyse polymorphic variations of HRH in patients with PD.</p> <p>Methods</p> <p>Leukocytary DNA from 195 PD patients and a control group of 231 unrelated healthy individuals was studied for the nonsynonymous HRH1Leu449Ser and the promoter HRH2G-1018A polymorphisms by using amplification-restriction analyses.</p> <p>Results</p> <p>The HRH1Leu449Ser amino acid substitution was identified in two women with late-onset PD whereas it was not observed among healthy subjects. The HRH2G-1018A polymorphism was observed with allele frequencies = 3.59 (95% CI = 1.74–5.44) and 5.0 (95% CI = 3.00–6.96) for patients with PD and healthy controls, respectively. These frequencies were independent of gender and age of onset of the disease. Multiple comparison analyses revealed that differences were not statistically significant.</p> <p>Conclusion</p> <p>These results indicate that the polymorphisms analyzed are not a major risk factor for PD, although the HRH1Leu449Ser amino acid substitution might be related to PD.</p