RESUMO
New complex-plasma facility, Plasmakristall-4 (PK-4), has been recently commissioned on board the International Space Station. In complex plasmas, the subsystem of µm-sized microparticles immersed in low-pressure weakly ionized gas-discharge plasmas becomes strongly coupled due to the high (103-104 e) electric charge on the microparticle surface. The microparticle subsystem of complex plasmas is available for the observation at the kinetic level, which makes complex plasmas appropriate for particle-resolved modeling of classical condensed matter phenomena. The main purpose of PK-4 is the investigation of flowing complex plasmas. To generate plasma, PK-4 makes use of a classical dc discharge in a glass tube, whose polarity can be switched with the frequency of the order of 100 Hz. This frequency is high enough not to be felt by the relatively heavy microparticles. The duty cycle of the polarity switching can be also varied allowing to vary the drift velocity of the microparticles and (when necessary) to trap them. The facility is equipped with two videocameras and illumination laser for the microparticle imaging, kaleidoscopic plasma glow observation system and minispectrometer for plasma diagnostics and various microparticle manipulation devices (e.g., powerful manipulation laser). Scientific experiments are programmed in the form of scripts written with the help of specially developed C scripting language libraries. PK-4 is mainly operated from the ground (control center CADMOS in Toulouse, France) with the support of the space station crew. Data recorded during the experiments are later on delivered to the ground on the removable hard disk drives and distributed to participating scientists for the detailed analysis.
RESUMO
Ovarian germ cell cancers are rare malignancies accounting for less than 5% of all ovarian cancers. We present a family in which three closely related women were diagnosed with ovarian germ cell malignancies. This family's cancer history prompted a family history investigation of women treated for ovarian germ cell malignancies in the Gynecologic-Oncology Clinic at the University of Wisconsin. One of the eight patients whose family histories were reviewed had an uncle who had been diagnosed with testicular germ cell cancer. A review found six other previously reported families in which more than one relative had been diagnosed with a malignant ovarian germ cell tumor. Additionally, several cases of families with both males and females diagnosed with germ cell cancers have been documented. The low incidence of ovarian germ cell cancers suggests that multiple occurrences in the same family may not be due to chance. Rather, it is possible that a gene conferring susceptibility to ovarian germ cell cancers, and possibly to germ cell tumors in males as well, is present in at least some of these families.
