ВАРИАЦИИ СИЛЫ ТЯЖЕСТИ И СОВРЕМЕННАЯ ГЕОДИНАМИКА ЮГОЗАПАДНОЙ ЧАСТИ БАЙКАЛЬСКОГО РЕГИОНА

Modern methods for determination of gravity values make it possible to obtain measurements with the accuracy up to 10–9 from g0 of the normal value (up to 1 microgal = 10 m/sec2). While all the systematic and periodic effects are excluded, a question is raised about stability of the gravity field of the Earth over time. Changes of the altitude (the Earth’s radius) with time can be estimated with an accuracy of 0.1 mm by modern space geodetic techniques, such as VLBI method. Our experiments for evaluation of stability of the gravity values over the past decades are based on the data obtained by Russian and foreign observatories using absolute ballistic laser gravimeters. The results put a limit of 10–10 per year to changes of the Earth’s radius. These estimations can be useful for testing hypotheses in tectonics.Measurements of non-tidal variations of gravity (Δg), which were obtained from 1992 to 2012 at the Talaya seismic station (located in the south-western part of the Baikal region), are interpreted together with GPS observation data. At the Talaya seismic station, the linear component of gravity variations corresponds to changes in the elevation of this site. The correlation coefficient is close to the normal value of the vertical gradient of gravity. At this site, coseismic gravity variations at the time of the Kultuk earthquake (27 August 2008, Mw=6.3) were caused by a combined effect of the change of the site’s elevation and deformation of the crust. Our estimations of the coseismic effects are consistent with results obtained by modeling based on the available seismic data.Современные методы определения значения силы тяжести позволяют проводить измерения с точностью до 10–9 от g0 нормального значения (до 1 микрогала = 10 нм/с2). При этом исключаются все систематические и периодические эффекты и возникает вопрос о стабильности поля силы тяжести Земли во времени. Оценить изменения высоты (радиуса Земли) во времени с точностью до 0.1 мм позволяют современные методы космической геодезии (VLBI метод). Экспериментальные оценки стабильности значения силы тяжести за последние десятилетия сделаны по материалам отечественных и зарубежных обсерваторий, использующих абсолютные лазерные баллистические гравиметры. Полученные результаты ограничивают изменение радиуса Земли значением 10–10 в год. Эти оценки можно использовать для тестирования тектонических гипотез.Результаты измерений неприливных вариаций ускорения силы тяжести Δg, проведенных в 1992–2012 гг. на сейсмостанции «Талая» (юго-западная часть Байкальского региона), интерпретируются совместно с данными GPS-наблюдений. Линейная составляющая вариации силы тяжести на станции Талая соответствует изменениям высоты пункта. Коэффициент корреляции близок к нормальному значению вертикального градиента силы тяжести. Косейсмические вариации силы тяжести на этом пункте в эпоху Култукского землетрясения (27.08.2008 г., Мw=6.3) вызваны комплексным эффектом изменения высоты пункта и деформации земной коры. Оценки косейсмических эффектов соответствуют результатам моделирования на основе сейсмологических данных

GRAVITY VARIATIONS AND RECENT GEODYNAMICS OF THE SOUTH-WESTERN PART OF THE BAIKAL REGION

Modern methods for determination of gravity values make it possible to obtain measurements with the accuracy up to 10–9 from g0 of the normal value (up to 1 microgal = 10 m/sec2). While all the systematic and periodic effects are excluded, a question is raised about stability of the gravity field of the Earth over time. Changes of the altitude (the Earth’s radius) with time can be estimated with an accuracy of 0.1 mm by modern space geodetic techniques, such as VLBI method. Our experiments for evaluation of stability of the gravity values over the past decades are based on the data obtained by Russian and foreign observatories using absolute ballistic laser gravimeters. The results put a limit of 10–10 per year to changes of the Earth’s radius. These estimations can be useful for testing hypotheses in tectonics.Measurements of non-tidal variations of gravity (Δg), which were obtained from 1992 to 2012 at the Talaya seismic station (located in the south-western part of the Baikal region), are interpreted together with GPS observation data. At the Talaya seismic station, the linear component of gravity variations corresponds to changes in the elevation of this site. The correlation coefficient is close to the normal value of the vertical gradient of gravity. At this site, coseismic gravity variations at the time of the Kultuk earthquake (27 August 2008, Mw=6.3) were caused by a combined effect of the change of the site’s elevation and deformation of the crust. Our estimations of the coseismic effects are consistent with results obtained by modeling based on the available seismic data

Oncometabolites in cancer aggressiveness and tumour repopulation

Tumour repopulation is recognized as a crucial event in tumour relapse where therapy-sensitive dying cancer cells influence the tumour microenvironment to sustain therapy-resistant cancer cell growth. Recent studies highlight the role of the oncometabolites succinate, fumarate, and 2-hydroxyglutarate in the aggressiveness of cancer cells and in the worsening of the patient's clinical outcome. These oncometabolites can be produced and secreted by cancer and/or surrounding cells, modifying the tumour microenvironment and sustaining an invasive neoplastic phenotype. In this review, we report recent findings concerning the role in cancer development of succinate, fumarate, and 2-hydroxyglutarate and the regulation of their related enzymes succinate dehydrogenase, fumarate hydratase, and isocitrate dehydrogenase. We propose that oncometabolites are crucially involved in tumour repopulation. The study of the mechanisms underlying the relationship between oncometabolites and tumour repopulation is fundamental for identifying efficient anti-cancer therapeutic strategies and novel serum biomarkers in order to overcome cancer relapse