Refugee flow or brain-drain? The humanitarian policy and post-Tiananmen mainland Chinese immigration to Canada

"The humanitarian policy that the Canadian government implemented in response to the 1989 Tiananmen Square crackdown changed a migration system primarily based on personal networks into a brain drain. Post-Tiananmen mainland Chinese immigrants (MCIs) were better educated than those arriving in Canada previously. Among the post-Tiananmen MCIs, those who landed under the policy were better educated than those landing in other categories. The analysis suggests that post-Tiananmen MCIs represented a brain-drain rather than a refugee flow, that the humanitarian policy implicitly contained ideological and human capital concerns in addition to humanitarian concerns, and that Canada benefited from the policy by obtaining human capital as well as satisfying its humanitarian obligations and ideological aspirations."     

The effect of an optically thin region on stability of an accretion disk around a supermassive black hole

We analyse conditions of the innermost portion of an accretion disk and establish a set of equations for this region. A stable innermost region may exist, which can probably explain the observed UV and X-ray spectra, avoiding the unstable emission. We then discuss the detailed radial structure of a disk around a black hole for typical AGN parameters and obtain different kinds of- relationships for different regions of a disk. On the basis of this, we discuss the stability. A new type of cycle is present, which we call a double S shaped cycle. In this cycle, the extent of accretion rate variability is much larger than that in dwarf nova cycles. This probably solves the problem of violent variability of AGN. In the meantime, the very high accretion rate at the hottest state in limit cycles in the unstable region may provide continuous injection of matter to the jet and power the relativistic motion of the jet.     

Microwave radiation from magnetic stars

Cyclotron microwave emission from magnetic stars is considered, assuming that they have coronae with the temperatureT10⁷ K and the emission measureEM10⁵⁴ cm^–3. It has been shown that the cyclotron radiation from a star with a dipole magnetic field has a specific spectrum with a maximum in the frequency rangesv _o/2 >v >sv _o/2 (s being the number of cyclotron harmonic, andv _o the gyrofrequency corresponding to the polar magnetic field) and radiation flux decreasing towards lower frequencies asv _4/3. The frequency of the spectrum maximum depends on the angle between the line-of-sight and the magnetic axis of the star. The observed radiation from a rotating magnetic star can be modulated with a modulation depth of about 0.2 at frequencies near maximum. The radiation is partially circularly-polarized in the sense of an extraordinary mode. The degree of polarization is almost constant at frequenciesv >sv _o/2 and increases with frequency atv >sv _o/2. The estimation of cyclotron radio fluxes of the nearest magnetic stars shows that they are observable in microwaves by means of modern radio astronomy.     

Models of pulsating low-massive yellow supergiants

The nonlinear self-excited oscillations of the envelopes of low-massive highly luminous stars are described. The parameters for these models wereM=0.8M ,M _bol=–5.5, –5.84 mag,T _eff=4500, 5000, 5500 K. The oscillations have been found to consist of the standing wave pulsation near the envelope bottom and running waves in outer layers. The ratio of the standing wave frequency _s to the average frequency of the running waves _r increases with the stellar luminosity: _s / _r =1.7 whenM _bol=–5.5 mag and _s / _r =2.4 whenM _bol=–5.84 mag. The frequency of oscillations near the photosphere is found to be in close agreement with the critical frequency for running waves. Mass loss from these stars is caused by shocks. It has been shown that agreement between FG Sge's period change observed during the last decade and the period-luminosity relation for double shell stars takes place when FG Sge's luminosity isM _bol=–5.96 mag.     

On geological processes on venus: Analysis of the relationship between altitude and degree of surface roughness

Aiming to study the relationship between Venus surface heights and surface roughness, the Pioneer Venus surface altitude map and map of r.m.s. slope in m-dkm scale have been analy sed for the Beta and Ishtar regions using a system of digital image processing. To integrate the data obtained, the results of geomorphological analysis of Venera 9 and 10 TV panoramas as well as gamma-spectrometric and photometric measurements were used. The analysis gives proof that Venera 9 and 10 landing sites represent geologic-morphologic situations typical of Venus, thus enabling the results of observations made at landing sites to be extended to large provinces. Apparently this conclusion is also applicable to the Venera 8 landing site. No strong relationship exists between the roughness of the surface and its altitude or the amount of a regional slope; neither for the Beta nor for the Ishtar region. A weak direct correlation observable for roughness-altitude pairs for the Beta region and roughness-altitude, roughness-slope pairs for the Ishtar region are quite obviously a consequence of regional roughness control, i.e. of an overall character of geological structure. On Venus the factors contributing to higher surface roughness on the m-dkm scale are, obviously, mostly volcanic and tectonic in their nature whilst those responsible for smoothing-out of the surface are chiefly exogenic. The rate of exogenic transformation of the Cytherean surface may be fairly high. On Venus, similarly as on the Earth, active tectono-magmatic processes have possibly taken place in recent geological epochs. One of the places where they are manifest is an extensive zone running from north to south across the Beta, Phoebe and Themis highlands. Within its limits occur both the process of basaltic shield-type volcanism and areal basalt effusions at low hypsometric levels accounting for the formation of lowland plains at the expense of ancient rolling plains. The basalts of the shield volcano Beta show some differences in composition compared to those of areal effusions at low hypsometric levels. The overall character of Cytherean tectonics in the recent geologic epoch is apparently block-type with a predominance of vertical movements. Against the background of the sinking of some of the blocks the other ones are rising and, possibly, such compensation upheavals have been responsible for the formation of the Ishtar region.