A non-main-sequence secondary in SY Cancri

Simultaneous spectroscopic and photometric observations of the Z Cam type dwarf nova SY Cancri were used to obtain absolute flux calibrations. A comparison of the photometric calibration with a wide slit spectrophotometric calibration showed that either method is equally satisfactory. A radial velocity study of the secondary star, made using the far red NaI doublet, yielded a mass ratio q = 0.68; this is very different from the value of 1.13 quoted in the literature. Using the new lower mass ratio, and constraining the mass of the white dwarf to be within reasonable limits, then leads to a mass for the secondary star that is substantially less than would be expected for its orbital period if it satisfied a main-sequence mass-radius relationship. We find a spectral type of M0 that is consistent with that expected for a main-sequence star of the low mass we have found. However, in order to fill its Roche lobe, the secondary must be significantly larger than a main sequence star of that mass and spectral type. The secondary is definitely not a normal main-sequence star.Comment: 13 pages, 9 figures, 6 tables, accepted for publication in MNRA

A study of event traffic during the shared manipulation of objects within a collaborative virtual environment

Event management must balance consistency and responsiveness above the requirements of shared object interaction within a Collaborative Virtual Environment (CVE) system. An understanding of the event traffic during collaborative tasks helps in the design of all aspects of a CVE system. The application, user activity, the display interface, and the network resources, all play a part in determining the characteristics of event management. Linked cubic displays lend themselves well to supporting natural social human communication between remote users. To allow users to communicate naturally and subconsciously, continuous and detailed tracking is necessary. This, however, is hard to balance with the real-time consistency constraints of general shared object interaction. This paper aims to explain these issues through a detailed examination of event traffic produced by a typical CVE, using both immersive and desktop displays, while supporting a variety of collaborative activities. We analyze event traffic during a highly collaborative task requiring various forms of shared object manipulation, including the concurrent manipulation of a shared object. Event sources are categorized and the influence of the form of object sharing as well as the display device interface are detailed. With the presented findings the paper wishes to aid the design of future systems

Opportunities and constraints of adopting market governance in protected areas in Central and Eastern Europe

This article analyses the transition from the traditional hierarchical governance of natural resources in Central and Eastern Europe towards the new forms of market governance of protected areas, including the introduction of fees and compensation. Our conceptual framework suggests that markets can be effective in governing transactions that involve low asset specificity and low frequency of disturbances. However, the introduction of markets should be accompanied by appropriate rules of market organization that particularly regulate their monitoring and impose sanctions in cases of mismanagement. The analysis of market governance in Poland, the Czech Republic and Slovakia reveals that in the face of decreasing funding for biodiversity protection and state budgetary problems, markets are more a necessity than a means to improve resource management. Although markets should complement rather than substitute traditional forms of governance, for certain types of transactions, markets are useful. They can be effectively implemented, provided that property rights are recognized and legal settings that regulate the monitoring and enforcement of market rules are set up

Rigorous asymptotics of traveling-wave solutions to the thin-film equation and Tanner's law

We are interested in traveling-wave solutions to the thin-film equation with zero microscopic contact angle (in the sense of complete wetting without precursor) and inhomogeneous mobility with slippage exponent n ∈ (3/2,7/3). Existence and uniqueness of these solutions have been established by Maria Chiricotto and the first of the authors in previous work under the assumption of subquadratic growth as h → ∞. In the present work we investigate the asymptotics of solutions as h → 0 (the contact-line region) and h → ∞. As h → 0 we observe, to leading order, the same asymptotics as for traveling waves or source-type self-similar solutions to the thin-film equation  with homogeneous mobility and we additionally characterize corrections to this law. Moreover, as h → ∞ we identify, to leading order, the logarithmic Tanner profile, i.e. the solution to the corresponding homogeneous problem that determines the apparent macroscopic contact angle. Besides higher-order terms, corrections turn out to affect the asymptotic law as h → ∞ only by setting the length scale in the logarithmic Tanner profile. Moreover, we prove that both the correction and the length scale depend smoothly on n. Hence, in line with the common philosophy, the precise modeling of liquid–solid interactions (within our model, the mobility exponent) does not affect the qualitative macroscopic properties of the film