The accretion disks are usually supposed symmetric to reflection on the Z=0 plane. Asymmetries in the flow are be ver-y small in the vicinity of the compact accretor. However their existence can have a important role in the case of subkeplerian accretion flows onto black holes. These flows lead to strong heating and even to the formation of shocks close to the centrifugal barrier. Large asymmetries are due to the development of the KH instability triggered by the small turbulences at the layer separating the incoming flow from the out coming shocked flow. The consequence of this phenomenon is the production of asymmetric outflows of matter and quasi periodic oscillations of the inner disk regions up and down the Z=0 plane.

The Committee has, for the 9th consecutive year, compiled statistics of embryos collected and transferred worldwide. Geographically, all regions have participated in the survey; however, there are still some places where it has been impossible to retrieve such data (particularly in Asia). The statistics, therefore, are partially underestimated. By contrast, in other areas, the system has proven to be more efficient than before, particularly in North and South America. This has resulted in the present report, which gives a somewhat more satisfactory picture of the current situation of the ET industry. For the second year, it has also been possible to collect data for several species other than cattle. In cattle, the number of in vivo-derived embryos collected and transferred has once again increased with more than half a million embryos trans-ferred in 1999(520,712), a new record. The number of bovine in vitro-produced embryos has remained stable this year as compared with the previous year(approximately 30,000 embryos transferred). However, there are still teams that have not Yet reported their data. More than 10,000 embryos in each of the ovine and caprine species and close to 2,000 cervid embryos were reported transferred in 1999. Some 500 embryos of the equine species and a few thousand in the porcine and rabbit species have also been transferred in 1999. It is concluded that the ET industry continues to be very active, and, in many species, it encompasses a larger segment of the livestock population overall, which is to the farmer s benefit.

국내 서식종 호박벌(Bombus ignitus)의 생태적 특성을 조사하기 위하여, 호박벌의 여왕벌을 야외에서 채집하여 온도 1, 상대습도 5% 및 암조건 하에서 실내사육하였다. 채집된 여왕벌의 산란율은 94.4%이었고, 채집 후 산란시기는 6.002.41일이었다. 산란된 알로부터 첫일벌 출현은 1.16일에, 첫수펄 출현은 3.94일이었다. 채집된 여왕벌의 봉군형성율은 86.1%이었고, 봉군을 형성한 채집 여왕벌 중에서 새여왕벌의 출현율은 96.8%였으며, 새여왕벌의 출현일은 6.88일이었다. 채집 여왕벌의 생존일수는 봉군을 형성한 여왕벌의 경우에 24.35일이었으며, 봉군을 형성하지 않은 여왕벌은 7.37일로 나타나, 봉군을 형성하는 여왕벌이 봉군을 형성하지 않는 여왕벌보다 약 5.5배 정도 수명이 길었다. 봉군의 크기를 조사한 결과, 일벌수는 18.23마리, 수펄수는 159.24마리, 여왕벌수는 47.48마리로 전체 봉군의 크기는 987.82145.84마리였다. 여왕벌의 출현기간을 조사한 결과, 6.95일의 단기형과 17.61일의 장기형의 2가지 형태가 나타났으며 이의 비율은 1:0.93이었다. 여왕벌과 수펄의 교미시간은 평균 7.33분이었다. 여왕벌이 산란한 난괴의 크기는 단경 0.88mm, 장경 1.11mm, 높이는 0.22mm이었다. 난괴당 난의 수는 평균 4.00개였으며, 난기간은 산란 후 3일이었다. 난의 크기는 단경 0.09mm, 장경 0.21mm로써 바나나형이며, 무게는 0.30mg이었다.

It. has been discovered that. active regions commonly have numerous flare-like transient. loop brightenings. We use a magnetic reconnection theory driven by a ponderamotive force on account. of the basic properties of a transient. brightening: lifetime a few mins, total energy 10 25~10 29 erg. The numerical results are consistent with the observations.

Assuming that particles can be accelerated to high energies via diffusive shock acceleration process at the accretion shocks formed by the infalling flow toward the clusters of galaxies, we have calculated the expected spectrum of high-energy protons from the cosmological ensemble of the cluster accretion shocks. The model with Jokipii diffusion limit could explain the observed cosmic ray spectrum near 10 19eV with reasonable parameters and models if about 10-4 of the infalling kinetic energy can be injected into the intergalactic space as the high energy particles.

The local instabilities of accretion disks were extensively studied, with the considerations of radial advection, thermal diffusion and different disk geometry, dominated pressure and optical depth. Two inertial-acoustic modes in a geometrically thin, radiative cooling dominated disk depart from each other if very little advection is included. A geometrically slim, advection-dominated disk is found to be always stable if it is optically thin. However, if it is optically thick, the thermal diffusion has no effect on the stable viscous mode but has a significant contribution to enhance the thermal instability.

Within the next few years eclipsing binaries should yield primary distance measurements for the Magellanic Clouds as well as provide tests of theoretical low-metallicity stellar models.