In the present paper, we introduce some notions of variation using the statistical convergence with respect to power series method. By the use of the notions of variation, we prove criterions that can be used to verify convergence without using limit value. Also, some results that give relations between P-statistical variations are studied.

The article presents the results of a study of the biographies of Koreans from Central Asia living in the Ural city of Chelyabinsk, conducted in 2014−2020. The author raises a number of research questions: How do Central Asian Koreans see their future? Do they intend to stay in Chelyabinsk or plan to return to their homeland? Are they ready to emigrate to South Korea or any other country? The source base of the study is biographical interviews with migrants and participant observation materials. The methodological basis of the article is a transnational approach. Using this approach, the everyday practices of Koreans, implemented here and there, are analyzed. The article focuses on the transnational ties of informants in the interpersonal, family, economic and socio-cultural spheres and shows how the transnational space covering Russia, Central Asia, the United States, and South Korea is constituted with the help of these ties. It is established that the idea of returning to the homeland or the myth of return are present in some way in most migrant stories, having a significant impact on the vision of the past and strategies for the future. The functioning and development of the transnational present practiced by the interviewed Koreans is the foundation for realizing future scenarios on different sides of the border(s). The subjects\' willingness to relocate within the transnational space acquires a permanent and self-reproducing nature. In these conditions, more and more new participants are being drawn into the transnational space. The planning of the transnational future is directly influenced by the situation in which the migrant and his family find themselves. The picture of this future is largely associated with a high degree of uncertainty in the key points of the transnational space, the inability to track the entire spectrum of hidden factors, etc.

The Os Odontoideum (OD) is a closure defect of ossification at the nucleus of the odontoid, it was described in 1886 by Giacomini and comes from the Latin Os meaning bone and odontoid meaning tooth 2.\nObjective: To describe the combined technique for C1-C2 fixation in 3 clinical cases of the Hospital Regional de Alta Especialidad del Bajío. \n\nMaterials and Methods: We identified 3 patients with OD and performed Rx imaging studies of the cervical spine, simple and dynamic craniocervical junction, CT scan of the same region, CT angiography of supra-aortic vessels, cervical MRI, Electromyography (EMG), nerve conduction velocities (NCV) of the 4 extremities.\nFirst case\n58-year-old male with parenthesis of all four limbs, cervicalgia and disproportionate quadriparesis, 3/5 left upper limb, 4/5 right upper limb, 4/5 lower left limb for all myotomes, clinical data of pyramidal release such as hyperreflexia, Babinski and substitutes. C1-C2 instability is corroborated with X-ray and CT, alterations are found in EMG and VCN studies such as decreased nerve conduction and denervation. MRI registered cord compression at the level of the atlas (Figs. 1, 2). C1-C2 fixation was performed with the Magerl transarticular screw and the Gallie technique sublaminar wiring with heterologous bone graft.\n\nResults: The surgery performed was the combination of transarticular screw placement and sublaminar wiring without neurological, vascular or bone complications.\n Discussion and Conclusions: Combined C1-C2 fixation techniques provide stability and lower surgical risks than isolated fixation techniques.