Occurrence of pulsus alternans during anaesthesia of two dogs and one cat and its treatment

The authors report the occurrence of pulsus alternans, a condition characterised by the alternance of pulses of higher and lower amplitude, in two dogs and one cat under general anaesthesia. The presence of an underlying cardiac disease was confirmed in the cat but not in either dog, which – based on history and clinical findings – had presumably normal cardiovascular function before the anaesthetic. Possible mechanisms, including negative inotropy and haemodynamic and Frank‐Starling effects, as well as the role of general anaesthesia as the potential triggering factor, are discussed in this report. Ephedrine resulted in the successful treatment of pulsus alternans, as demonstrated by the return of normal pulse and synchronisation of heart and pulse rates in the cat and in one dog. In the other dog, pulse pattern and frequency returned to normal once the guidewire for central line placement was withdrawn

Ejaculate allocation by male sand martins, Riparia riparia

Males of many species allocate sperm to ejaculates strategically in response to variation in the risk and intensity of sperm competition. The notable exception is passerine birds, in which evidence for strategic allocation is absent. Here we report the results of a study testing for strategic ejaculate allocation in a passerine bird, the sand martin (Riparia riparia). Natural ejaculates were collected from males copulating with a model female. Ejaculates transferred in the presence of a rival male contained significantly more sperm than ejaculates transferred in the absence of a rival male. There was no evidence that this difference was due to the confounding effects of the year of ejaculate collection, the identity of the model female, the colony, the stage of season or the period of the day in which ejaculates were collected. A more detailed examination of the ejaculate patterns of individual males, achieved by the DNA profiling of ejaculates, provided additional evidence for strategic allocation of sperm

Eccentric Ellipsoidal Red Giant Binaries in the LMC: Complete Orbital Solutions and Comments on Interaction at Periastron

Modelling ellipsoidal variables with known distances can lead to exact determination of the masses of both components, even in the absence of eclipses. We present such modelling using light and radial velocity curves of ellipsoidal red giant binaries in the LMC, where they are also known as sequence E stars. Stars were selected as likely eccentric systems on the basis of light curve shape alone. We have confirmed their eccentric nature and obtained system parameters using the Wilson-Devinney code. Most stars in our sample exhibit unequal light maxima as well as minima, a phenomenon not observed in sequence E variables with circular orbits. We find evidence that the shape of the red giant changes throughout the orbit due to the high eccentricity and the varying influence of the companion. Brief intervals of pulsation are apparent in two of the red giants. We determine pulsation modes and comment on their placement in the period-luminosity plane. Defining the parameters of these systems paves the way for modelling to determine by what mechanism eccentricity is maintained in evolved binaries.Comment: 14 pages, 11 figures. Accepted to MNRAS 2012 January