We report on the long-term variability of the Be/X-ray binary LS I +61◦ 235/RX J0146.9+6121. New optical spectroscopic and infrared photometric observations confirm the presence of global one-arm oscillations in the circumstellar disc of the Be star and allow us to derive a V/R quasi-period of 1240±30 days. Pronounced shell events, reminiscent of the spectacular variations in Be stars, are also...

Let X be a compact 2-manifold with nonempty boundary ∂X and let f : (X, ∂X) → (X, ∂X) be a boundary-preserving map. Denote by MF∂ [f ] the minimum number of fixed point among all boundary-preserving maps that are homotopic through boundary-preserving maps to f . The relative Nielsen number N∂(f) is the sum of the number of essential fixed point classes of the restriction f̄ : ∂X → ∂X and the num...

The Galactic black hole candidate XTE J1752−223 was observed during the decay of its 2009 outburst with the Suzaku and XMM–Newton observatories. The observed spectra are consistent with the source being in the ‘intermediate’ and ‘low-hard’ states, respectively. The presence of a strong, relativistic iron emission line is clearly detected in both observations and the line profiles are found to b...

Justham, Rappaport & Podsiadlowski (2006) recently suggested that black-hole lowmass X-ray binaries (BHLMXBs) with short orbital periods may have evolved from black-hole intermediate-mass X-ray binaries (BHIMXBs). In their model the secondaries in BHIMXBs are assumed to possess anomalously high magnetic fields, so that magnetic braking can lead to substantial loss of angular momentum. In this p...

We present the first mid-IR long baseline interferometric observations of the circumstellar matter around binary post-AGB stars. Two objects, SX Cen and HD 52961, were observed using the VLTI/MIDI instrument during Science Demonstration Time. Both objects are known binaries for which a stable circumbinary disc is proposed to explain the SED characteristics. This is corroborated by our N-band sp...

The new compact disc from the Department of Veterans Affairs, Tonal and Speech Materials for Auditory, Perceptual Assessment, Disc 2.0 (1998), contains two lists of randomly interleaved 1-, 2-, and 3-pair dichotic digits. Two experiments are reported, in which the effects of low-pass filtering and inter-digit interval on dichotic digit recognition were investigated in adult listeners with norma...

The combined effects of hydrostatic pressure and temperature on the optical absorption coefficient and refractive index changes of a hydrogenic impurity in a disc-shaped quantum dot with parabolic confinement in the presence of an external electric field have been investigated by using the perturbation method within the effective-mass approximation. Analytical expressions for the linear and thi...

We algebraically analysis the quantum Hall effect of a system of particles living on the disc B1 in the presence of an uniform magnetic field B. For this, we identify the non-compact disc with the coset space SU(1, 1)/U(1). This allows us to use the geometric quantization in order to get the wavefunctions as the Wigner D-functions satisfying a suitable constraint. We show that the corresponding...

To achieve high quality and reliability in mechatronics products, thorough consideration of dynamic performance in structural design is essential. Typical examples include the design of optical pick-ups for disk related products, such as Compact Disc (CD) drives, and Magneto-optical Disc (MO) drives. Many researchers have developed design methodologies to optimize the nominal dynamic characteri...

Basic trade-offs between the rate of combined DC-free runlength-limited (DCRLL) modulation codes and the amount of suppression of low-frequency components are presented. The main results are obtained by means of a numerical study of dependencies between statistical properties of ideal, ‘maxentropic’ DCRLL sequences. The numerical results are mathematically founded by proving the observed behavi...