This work aims to present our current best physical understanding of common-envelope evolution (CEE). We highlight areas of consensus and disagreement, and stress ideas which should point the way ...forward for progress in this important but long-standing and largely unconquered problem. Unusually for CEE-related work, we mostly try to avoid relying on results from population synthesis or observations, in order to avoid potentially being misled by previous misunderstandings. As far as possible we debate all the relevant issues starting from physics alone, all the way from the evolution of the binary system immediately before CEE begins to the processes which might occur just after the ejection of the envelope. In particular, we include extensive discussion about the energy sources and sinks operating in CEE, and hence examine the foundations of the standard energy formalism. Special attention is also given to comparing the results of hydrodynamic simulations from different groups and to discussing the potential effect of initial conditions on the differences in the outcomes. We compare current numerical techniques for the problem of CEE and also whether more appropriate tools could and should be produced (including new formulations of computational hydrodynamics, and attempts to include 3D processes within 1D codes). Finally we explore new ways to link CEE with observations. We compare previous simulations of CEE to the recent outburst from V1309 Sco, and discuss to what extent post-common-envelope binaries and nebulae can provide information, e.g. from binary eccentricities, which is not currently being fully exploited.
Aims. We aim to determine the geometry, density gradient, and velocity structure of jets in post-asymptotic giant branch (post-AGB) binaries. Methods. Our high cadence time series of high-resolution ...optical spectra of jet-creating post-AGB binary systems provide us with a unique tomography of the jet. We determine the spatio-kinematic structure of the jets based on these data by fitting the synthetic spectral line profiles created by our model to the observed, orbital phase-resolved, Hα-line profiles of these systems. The fitting routine is provided with an initial spectrum and is allowed to test three configurations, derived from three specific jet launching models: a stellar jet launched by the star, an X-wind, and a disk wind configuration. We apply a Markov-chain Monte Carlo routine in order to fit our model to the observations. Our fitting code is tested on the post-AGB binary IRAS 19135+3937. Results. We find that a model using the stellar jet configuration gives a marginally better fit to our observations. The jet has a wide half-opening angle of about 76° and reaches velocities up to 870 km s−1. Conclusions. Our methodology is successful in determining some parameters for jets in post-AGB binaries. The model for IRAS 19135+3937 includes a transparent, low density inner region (for a half-opening angle < 40°). The source feeding the accretion disk around the companion is most likely the circumbinary disk. We will apply this jet fitting routine to other jet-creating post-AGB stars in order to provide a more complete description of these objects.
The occurrence of stellar wind in the central star of a planetary nebula (CSPN) can be revealed by the presence of P Cygni profiles of high-excitation lines overimposed on its stellar continuum. We ...examined the entire Far-Ultraviolet Spectroscopic Explorer (FUSE) archive and merged all useful spectroscopic observations of CSPNe to produce the highest quality spectra that can be used to assess the frequency of stellar winds. Furthermore, the individual spectra of each CSPN were compared to search for variability in the P Cygni profile. P Cygni profiles of high-excitation lines have been found in 44 CSPNe, with a clear correlation between the ionization potential of the lines and the effective temperature of the star. We introduce a prescription to derive the terminal wind velocity (v∞) from saturated and unsaturated P Cygni profiles and provide new values of v∞ for these stars. Another 23 CSPNe do not show P Cygni profiles, or else their data in the FUSE archive are not conclusive enough to determine the occurrence of P Cygni profiles. Variability in the P Cygni profile of high-excitation, far-UV lines is found for the first time in six CSPNe, namely Hen 2-131, NGC 40, NGC 1535, NGC 2392, Sp 3, and SwSt 1. This increases up to 13 the number of CSPNe with variable P Cygni profiles in the UV, including those previously reported using IUE or FUSE observations. Variability is seen primarily in the unsaturated P v and Si iv lines, but also in saturated C iii and O vi lines. The CSPNe with variable P Cygni profiles have similar stellar properties (relatively low log (g) and Teff) that suggest they are less evolved CSPNe. Some of the CSPNe with variable P Cygni profiles show O vi lines, while their effective temperature is insufficient to produce this ion. We suggest that this ion is produced by Auger ionization from X-rays associated to shocks in their stellar winds, as is the case in massive OB stars of high ionization potential ions that cannot be abundantly produced by photoionizations.
The importance of long-period binaries for the formation and evolution of planetary nebulae is still rather poorly understood, which in part is due to the lack of central star systems that are known ...to comprise such long-period binaries. Here, we report on the latest results from the on-going Mercator-HERMES survey for variability in the central stars of planetary nebulae. We present a study of the central stars of NGC 1514, BD+30°623, the spectrum of which shows features associated with a hot nebular progenitor as well as a possible A-type companion. Cross-correlation of high-resolution HERMES spectra against synthetic spectra shows the system to be a highly eccentric (e ~ 0.5) double-lined binary with a period of ~3300 days. Previous studies indicated that the cool component might be a horizontal branch star of mass ~0.55 M⊙, but the observed radial velocity amplitudes rule out such a low mass. If we assume that the nebular symmetry axis and binary orbital plane are perpendicular, then the data are more consistent with a post-main-sequence star ascending towards the giant branch. We also present the continued monitoring of the central star of LoTr 5, HD 112313, which has now completed one full cycle, allowing the orbital period (P~2700 days) and eccentricity (e ~ 0.3) to be derived. To date, the orbital periods of BD+30°623 and HD 112313 are the longest to have been measured spectroscopically in the central stars of planetary nebulae. Furthermore, these systems, along with BD+33°2642, comprise the only spectroscopic wide-binary central stars currently known.
Aims.
In this study we determine the morphology and mass-loss rate of jets emanating from the companion in post-asymptotic giant branch (post-AGB) binary stars with a circumbinary disc. In doing so ...we also determine the mass-accretion rates onto the companion, and investigate the source feeding the circum-companion accretion disc.
Methods.
We perform a spatio-kinematic modelling of the jet of two well-sampled post-AGB binaries, BD+46°442 and IRAS 19135+3937, by fitting the orbital phased time series of H
α
spectra. Once the jet geometry, velocity, and scaled density structure are computed, we carry out radiative transfer modelling of the jet for the first four Balmer lines to determine the jet densities, thus allowing us to compute the jet mass-loss rates and mass-accretion rates. We distinguish the origin of the accretion by comparing the computed mass-accretion rates with theoretically estimated mass-loss rates, both from the post-AGB star and from the circumbinary disc.
Results.
The spatio-kinematic model of the jet reproduces the observed absorption feature in the H
α
lines. The jets have an inner region with extremely low density in both objects. The jet model for BD+46°442 is tilted by 15° with respect to the orbital axis of the binary system. IRAS 19135+3937 has a smaller tilt of 6°. Using our radiative transfer model, we find the full 3D density structure of both jets. By combining these results, we can compute the mass-loss rates of the jets, which are of the order of 10
−7
− 10
−5
M
⊙
yr
−1
. From this we estimate mass-accretion rates onto the companion of 10
−6
− 10
−4
M
⊙
yr
−1
.
Conclusions.
Based on the mass-accretion rates found for these two objects, we conclude that the circumbinary disc is most likely the source feeding the circum-companion accretion disc. This is in agreement with the observed depletion patterns in post-AGB binaries, which is caused by re-accretion of gas from the circumbinary disc that is under-abundant in refractory elements. The high accretion rates from the circumbinary disc imply that the lifetime of the disc will be short. Mass transfer from the post-AGB star cannot be excluded in these systems, but it is unlikely to provide a sufficient mass-transfer rate to sustain the observed jet mass-loss rates.
Malpighiaceae has undergone unprecedented changes in its traditional classification in the past two decades due to several phylogenetic studies shedding light on the non-monophyly of all subfamilies ...and most tribes and genera. Even though morphological characters were used to reconstruct the last molecular generic phylogeny of Malpighiaceae, a new classification system has never been proposed for this family. Based on a comprehensive review of the last twenty years of published studies for this family, we propose a new classification system and provide a taxonomic synopsis for Malpighiaceae based on molecular phylogenetics, morphology, palynology, and chemistry as a baseline for the systematics, conservation, and taxonomy of this family worldwide. Malpighiaceae currently comprises two subfamilies (Byrsonimoideae and Malpighioideae), 12 tribes ( Acmanthereae, Acridocarpeae
, Barnebyeae
, Bunchosieae
, Byrsonimeae, Galphimieae, Gaudichaudieae, Hiptageae, Hiraeeae, Malpighieae, Mcvaughieae
, and Ptilochaeteae
), 72 genera (incl.
), and 1,499 accepted species (715 of which are currently under some kind of extinction threat). We present identification keys for all subfamilies, tribes, and genera, a full morphological description for the proposed new genus, the re-circumscription of ten genera alongside the needed new combinations, the proposition of several new synonyms, the typification of several names, and notes on the taxonomy, distribution, conservation, and ecology up to the genus rank. Morphological plates are also provided to illustrate the immense diversity of morphological traits used in the new classification and synopsis.
Se analiza la presencia de metales pesados en tejidos de organismos provenientes del sector aledaño a Isla Rocuant, Bahía Concepción. Los organismos estudiados fueron los bivalvos bentónicos Tagelus ...dombeii ("navajuela"), Mulinia edulis ("taquilla"), las macroalgas Gracilaria chilensis ("pelillo") y Rhodymenia sp ("rodymenia") y el pez Stromateus stellatus ("pampanito"). Los metales analizados en sus tejidos fueron Cd, Fe, Hg, Pb y Zn para los cuales no existen registros previos en la localidad. La obtención de las muestras fue realizada por medio de buceo "hooka" para los organismos bentónicos, mientras que los peces fueron capturados mediante redes de pesca. En general, los metales encontrados presentan concentraciones comparables con los valores reportados en la literatura para las misma especies, pero en otras localidades, por lo que reflejan una condición natural, indicando además que los niveles de Cd, Hg y Pb en los moluscos bivalvos se encuentran bajo los niveles de aceptación para productos de exportación. Se destaca además que en el caso del Pb, este se encuentra bajo los niveles de detección analíticas en todos los organismos, al igual que el Cd en el pez S. stellatus y el alga G. chilensis. Otra diferencia que resalta corresponde a la presencia de Fe en Rhodymenia sp. que presenta el mayor valor absoluto de todo el estudio.
The meadow spittlebug, Philaenus spumarius L. (Hemiptera, Aphrophoridae) is a commonly found vector of Xylella fastidiosa Wells et al. (1987) strain subspecies pauca associated with the "Olive Quick ...Decline Syndrome" in Italy. To contribute to the knowledge of the adult P. spumarius chemoreceptivity, electroantennographic (EAG) responses of both sexes to 50 volatile organic compounds (VOCs) including aliphatic aldehydes, alcohols, esters, and ketones, terpenoids, and aromatics were recorded. Measurable EAG responses were elicited by all compounds tested. In both sexes, octanal, 2-octanol, 2-decanone, (E)-2-hexenyl acetate, and vanillin elicited the strongest antennal amplitude within the chemical groups of aliphatic saturated aldehydes, aliphatic alcohols, aliphatic acetates and aromatics, respectively. Male and female EAG responses to sulcatol, (±)linalool, and sulcatone were higher than those to other terpenoinds. In both sexes, the weakest antennal stimulants were phenethyl alcohol and 2-pentanone. Sexual differences in the EAG amplitude were found only for four of test compounds suggesting a general similarity between males and females in antennal sensitivity. The olfactory system of both sexes proved to be sensitive to changes in stimulus concentration, carbon chain length, and compound structure. Compounds with short carbon chain length (C5-C6) elicited lower EAG amplitudes than compounds with higher carbon chain length (C9-C10) in all classes of aliphatic hydrocarbons with different functional groups. The elucidation of the sensitivity profile of P. spumarius to a variety of VOCs provides a basis for future identification of behaviorally-active compounds useful for developing semiochemical-based control strategies of this pest.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
IntroductionAcute laryngeal dystonia due to antipsychotics is an uncommon but potentially lethal form of extrapyramidal reaction. The initial symptoms may be subtle but progressively appear ...difficulties in phonation, stridor and dyspnea which are often life-threatening.ObjectivesTo describe a case of acute laryngeal dystonia and oculogyric crisis secondary to risperidone.MethodsThe present study is a case report of a patient admitted for schizophrenia who was presented a laryngeal dystonia and oculogyric crisis after being treated with 5mg risperidone. We also searched previously case reports, series and systematic reviews of laryngeal dystonia using a pubmed query.ResultsA 30-year-old Caucasian woman who was admitted for schizophrenia presented rhinolalia, oropharynx paresthesias, mild dyspnea without stridor, and prolonged involuntary upword desviation of the eyes. All these symptoms started within 24 hours of starting risperidone 5mg per day. A laryngoscopy showed abnormal motion of the vocal cords that suggested laryngeal dystonia. Symptoms remitted after administration of intramuscular biperiden 4mg. Risperidone was later switched to olanzapine because of better psychomotor side-effect profile.ConclusionsLaryngeal dystonia is a medical emergency requiring early diagnosis and immediate treatment. Anticholinergic agents should be carried out, without waiting for the results of complementary tests. The route of administration can be intramuscular or intravenous. This complication should be always kept into account when a patient is taking any antipsychotic, and remembered for the antipsychotic election in following treatments.Disclosure of InterestNone Declared
•Interconnecting grounding systems of a wind farm strongly reduces the resistance.•Interconnecting grounding systems does not improve impulse response in all cases.•Improvement of the impulse ...response with interconnection rises with resistivity.•Interconnecting electrode length to be considered is given by the effective length.•Care should be taken with transferred voltages through interconnecting electrodes.
Previous analysis of the lightning response of wind turbine grounding systems has often considered only one unit. This paper investigates the impulse and low-frequency performance of isolated and interconnected grounding systems of wind turbines, subjected to lightning currents representative of first and subsequent negative downward strokes and return strokes associated with upward negative flashes. The system behavior is studied for different lengths of interconnecting conductor between adjacent grounding systems and for distinct values of soil resistivity considering frequency-dependent soil parameters. It is shown that in the case of lightning currents with shorter front-times, the interconnection improves the impulse response of grounding, reducing the GPR peak, only for soils of higher resistivity, whereas in the case of currents with longer front-times, the interconnecting improves the impulse response in all cases. The relative improvement of the impulse response when the adjacent grounding systems are interconnected becomes more significant with the increase of the soil resistivity. In all cases, interconnecting the grounding systems strongly reduces the low-frequency grounding resistance seen by each individual wind turbine earth termination.
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