2,540 research outputs found
Predicting the Future of Superhumps in Classical Nova Systems
Oscillations observed in the light curve of Nova V1974 Cygni 1992 since
summer 1994 have been interpreted as permanent superhumps. From simple
calculations based on the Tidal-Disk Instability model of Osaki, and assuming
that the accretion disc is the dominant optical source in the binary system, we
predict that the nova will evolve to become an SU UMa system as its brightness
declines from its present luminosity by another 2-3 magnitudes. Linear
extrapolation of its current rate of fading (in magnitude units) puts the time
of this phase transition within the next 2-4 years. Alternatively, the
brightness decline will stop before the nova reaches that level, and the system
will continue to show permanent superhumps in its light curve. It will then be
similar to two other old novae, V603 Aql and CP Pup, that still display the
permanent superhumps phenomenon 79 and 55 years, respectively, after their
eruptions. We suggest that non-magnetic novae with short orbital periods could
be progenitors of permanent superhump systems.Comment: 5 pages, 2 eps. figures, Latex, accepted for publication in MNRA
Nova V1425 Aquilae 1995 - The Early Appearance of Accretion Processes in An Intermediate Polar Candidate
Continuous CCD photometry of Nova Aquilae 1995 was performed through the
standard B,V,R and I filters during three nights in 1995 and with the I filter
during 18 nights in 1996. The power spectrum of the 1996 data reveals three
periodicities in the light curve: 0.2558 d, 0.06005 d and 0.079 d, with
peak-to-peak amplitudes of about 0.012, 0.014 and 0.007 mag. respectively.
The two shorter periods are absent from the power spectrum of the 1995 light
curve, while the long one is probably already present in the light curve of
that year.
We propose that V1425 Aql should be classified as an Intermediate - Polar CV.
Accordingly the three periods are interpreted as the orbital period of the
underlying binary system, the spin period of the magnetic white dwarf and the
beat period between them. Our results suggest that no later than 15 months
after the outburst of the nova, accretion processes are taking place in this
stellar system. Matter is being transferred from the cool component, most
likely through an accretion disc and via accretion columns on to the magnetic
poles of the hot component.Comment: 7 pages, 4 eps. figures, Latex, accepted for publication in MNRA
Examining How Auditing Text Books Cover the AICPA’s Conceptual Frameworks for Ethics
The AICPA’s Codification of the Code of Professional Conduct (the Revised Code), issued in June 2014, features two “principle-based” conceptual frameworks that employ a “threats and safeguards” approach to CPAs’ ethical dilemmas. These 2014 conceptual frameworks reprise concepts and terminology from similar AICPA 2006 and 2008 conceptual frameworks. This article discusses the heightened relevance of principle-based conceptual frameworks and examines how eight major auditing textbooks, all written since the 2006 and 2008 frameworks, cover how contemporary principles-based professional ethics supplement and enhance traditional “rules-based” ethics. The results show that few of the eight examined auditing textbooks cover adequately or at all the Code of Professional Conduct’s conceptual frameworks. An appendix presents materials to help auditing professors augment their classroom coverage and to help auditing textbook authors strengthen their future textbook editions
Breeding structure of Drosophila buzzatii in relation to competition in prickly pears (Opuntia ficus-indica)
No Right to Remain Silent: Isolating Malicious Mixes
Mix networks are a key technology to achieve network anonymity and private messaging, voting and database lookups. However, simple mix network designs are vulnerable to malicious mixes, which may drop or delay packets to facilitate traffic analysis attacks. Mix networks with provable robustness address this drawback through complex and expensive proofs of correct shuffling but come at a great cost and make limiting or unrealistic systems assumptions. We present Miranda, an efficient mix-net design, which mitigates active attacks by malicious mixes. Miranda uses both the detection of corrupt mixes, as well as detection of faults related to a pair of mixes, without detection of the faulty one among the two. Each active attack -- including dropping packets -- leads to reduced connectivity for corrupt mixes and reduces their ability to attack, and, eventually, to detection of corrupt mixes. We show, through experiments, the effectiveness of Miranda, by demonstrating how malicious mixes are detected and that attacks are neutralized early
Breeding structure of Drosophila buzzatii in relation to competition in prickly pears (Opuntia ficus-indica)
International audienc
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