Flux Creep and Flux Jumping

We consider the flux jump instability of the Bean's critical state arising in the flux creep regime in type-II superconductors. We find the flux jump field, $B_j$, that determines the superconducting state stability criterion. We calculate the dependence of $B_j$ on the external magnetic field ramp rate, $\dot B_e$. We demonstrate that under the conditions typical for most of the magnetization experiments the slope of the current-voltage curve in the flux creep regime determines the stability of the Bean's critical state, {\it i.e.}, the value of $B_j$. We show that a flux jump can be preceded by the magneto-thermal oscillations and find the frequency of these oscillations as a function of $\dot B_e$.Comment: 7 pages, ReVTeX, 2 figures attached as postscript file

Composition of Fluids Responsible for Gold Mineralization in the Pechenga Structure-Imandra-Varzuga Greenstone Belt, Kola Peninsula, Russia.

This study presents the first fluid inclusion data from quartz of albite–carbonate–quartz altered rocks and metasomatic quartzite hosting gold mineralization in the Pechenga structure of the Pechenga– Imandra–Varzuga greenstone belt. A temperature of 275–370°C, pressure of 1.2–4.5 kbar, and the fluid composition of gold-bearing fluid are estimated by microthermometry, Raman spectroscopy, and LA-ICP-MS of individual fluid inclusions, as well as by bulk chemical analyses of fluid inclusions. In particular, the Au and Ag concentrations have been determined in fluid inclusions. It is shown that albite–carbonate–quartz altered rocks and metasomatic quartzite interacted with fluids of similar chemical composition but under different physicochemical conditions. It is concluded that the gold-bearing fluid in the Pechenga structure is similar to that of orogenic gold deposits

Gaia Early Data Release 3: The celestial reference frame (Gaia-CRF3)

Context. Gaia-CRF3 is the celestial reference frame for positions and proper motions in the third release of data from the Gaia mission, Gaia DR3 (and for the early third release, Gaia EDR3, which contains identical astrometric results). The reference frame is defined by the positions and proper motions at epoch 2016.0 for a specific set of extragalactic sources in the (E)DR3 catalogue. Aims. We describe the construction of Gaia-CRF3 and its properties in terms of the distributions in magnitude, colour, and astrometric quality. Methods. Compact extragalactic sources in Gaia DR3 were identified by positional cross-matching with 17 external catalogues of quasi-stellar objects (QSO) and active galactic nuclei (AGN), followed by astrometric filtering designed to remove stellar contaminants. Selecting a clean sample was favoured over including a higher number of extragalactic sources. For the final sample, the random and systematic errors in the proper motions are analysed, as well as the radio-optical offsets in position for sources in the third realisation of the International Celestial Reference Frame (ICRF3). Results. Gaia-CRF3 comprises about 1.6 million QSO-like sources, of which 1.2 million have five-parameter astrometric solutions in Gaia DR3 and 0.4 million have six-parameter solutions. The sources span the magnitude range G = 13-21 with a peak density at 20.6 mag, at which the typical positional uncertainty is about 1 mas. The proper motions show systematic errors on the level of 12 μas yr-1 on angular scales greater than 15 deg. For the 3142 optical counterparts of ICRF3 sources in the S/X frequency bands, the median offset from the radio positions is about 0.5 mas, but it exceeds 4 mas in either coordinate for 127 sources. We outline the future of Gaia-CRF in the next Gaia data releases. Appendices give further details on the external catalogues used, how to extract information about the Gaia-CRF3 sources, potential (Galactic) confusion sources, and the estimation of the spin and orientation of an astrometric solution

Risk-reducing hysterectomy and bilateral salpingo-oophorectomy in female heterozygotes of pathogenic mismatch repair variants: a Prospective Lynch Syndrome Database report

Purpose To determine impact of risk-reducing hysterectomy and bilateral salpingo-oophorectomy (BSO) on gynecological cancer incidence and death in heterozygotes of pathogenic MMR (path_MMR) variants. Methods The Prospective Lynch Syndrome Database was used to investigate the effects of gynecological risk-reducing surgery (RRS) at different ages. Results Risk-reducing hysterectomy at 25 years of age prevents endometrial cancer before 50 years in 15%, 18%, 13%, and 0% of path_MLH1, path_MSH2, path_MSH6, and path_PMS2 heterozygotes and death in 2%, 2%, 1%, and 0%, respectively. Risk-reducing BSO at 25 years of age prevents ovarian cancer before 50 years in 6%, 11%, 2%, and 0% and death in 1%, 2%, 0%, and 0%, respectively. Risk-reducing hysterectomy at 40 years prevents endometrial cancer by 50 years in 13%, 16%, 11%, and 0% and death in 1%, 2%, 1%, and 0%, respectively. BSO at 40 years prevents ovarian cancer before 50 years in 4%, 8%, 0%, and 0%, and death in 1%, 1%, 0%, and 0%, respectively. Conclusion Little benefit is gained by performing RRS before 40 years of age and premenopausal BSO in path_MSH6 and path_PMS2 heterozygotes has no measurable benefit for mortality. These findings may aid decision making for women with LS who are considering RRS.Hereditary cancer genetic

Mesoarchean kola-karelia continent

The Mesoarchean Kola-Karelia continent in the eastern Fennoscandian Shield includes three tectonic provinces, Kola, Karelia and Belomoria, that were formed by the Paleoarchean and Mesoarchean microcontinents. Traces of Mesoarchean tonalite-trondhjemite-granodiorite (TTG)-type early crust were documented in all of the most ancient units of the Kola-Karelia continent. Ancient crust was revealed and dated in the Ranua and Iisalmi microcontinents, 3.5-3.4 Ga; Vodlozero and Khetolambina microcontinents, 3.25-3.15 Ga; Kuhmo-Segozero microcontinent, 3.0 Ga; Murmansk and Inari-Kola microcontinents, 2.93 Ga; and Kianta microcontinent, 2.83-2.81 Ga. In the older (>3.0 Ga) tectonic units and microcontinents, the ancient crust was possibly formed in brief bursts of endogenic activity. In younger microcontinents (3.0-2.93 Ga), these processes could continue until 2.8 and even 2.72 Ga. The tectonic settings in which early TTG crust has been produced are largely uncertain. The primary melt glassy inclusions with a glass phase in cores of prismatic zircon crystals from TTG gneisses provide evidence for the volcanic origin of gneiss protolith. Suggested genetic modeling of TTG-type complexes assumes that felsic K-Na melts with positive Eu anomaly are a product of dry high-temperature partial melting of the previously formed mafic-to-felsic crustal rocks and/or thick older TTG crust. Positive Eu anomaly in the eutectic is directly related to the predominance of plagioclase and K-feldspar in the melt. TTG-type crust melted to produce granitegranodiorite (GG) rocks. Earliest microcontinents are separated by Mesoarchean greenstone belts (mainly 3.05-2.85 Ga, in some cases up to 2.75 Ga), which are fragments of paleo-islandarc systems accreted to their margins: the Kolmozero-Voronya, Central Belomorian, Vedlozero-Segozero, Sumozero-Kenozero, and Tipasjärvi-Kuhmo-Suomussalmi belts; and the mature island arcs (microcontinents): Khetolambina and Kovdozero. These structural units are characterized by significant extent, close to rectilinear trend, localization along the boundaries between Archean microcontinents, and a specific set of petrotectonic assemblages (basalt-andesite-rhyolite, komatiite-tholeiite, and andesite-dacite associations). The recently discovered Meso-Neoarchean Belomorian eclogite province that is structurally linked with the Central Belomorian greenstone belt contains two eclogite associations distributed within TTG gneisses: the subduction-type Salma association and the Gridino eclogitized mafic dikes. The protolith of the Salma eclogites is thought to have been a sequence of gabbro, Fe-Ti gabbro, and troctolite, formed at ca. 2.9 Ga in a slow-spreading ridge (similar to the Southwest Indian Ridge). The main subduction and eclogite-facies events occurred between ca. 2.87 and ca. 2.82 Ga. Mafic magma injections into the crust of the active margin that led to formation of the Grigino dike swarm were associated with emplacement of a mid-ocean ridge in a subduction zone, beginning at ca. 2.87 Ga. Crustal delamination of the active margin and subsequent involvement of the lower crust in subduction 2.87-2.82 Ga ago led to high-pressure metamorphism of the Gridino dikes that reached eclogite-facies conditions during a collision event between 2.82 and 2.78 Ga. This collision resulted in consolidation of the Karelia, Kola, and Khetolamba blocks and formation of the Mesoarchean Belomorian accretionary-collisional orogen. To date, the subductionrelated Salma eclogites provide the most complete and meaningful information on the nature of plate tectonics in the Archean, from ocean-fl oor spreading to subduction and collision. The Kovdozero granite-greenstone terrain that separates the Khetolambina and Kuhmo-Segozero microcontinents is formed by TTG granitoids and gneisses hosting metasediments and metavolcanics of several greenstone belts, which belonged to the Parandovo-Tiksheozero island arc that existed from ca. 2.81 to 2.77 Ga. The Iringora greenstone belt includes the ophiolite complex of the same name with an age of 2.78 Ga. The collision of microcontinents resulted in the upward squeezing of the island arc and the obduction of its marginal portions onto surrounding structures. © 2015 The Geological Society of America. All rights reserved

Mesoarchean kola-karelia continent

The Mesoarchean Kola-Karelia continent in the eastern Fennoscandian Shield includes three tectonic provinces, Kola, Karelia and Belomoria, that were formed by the Paleoarchean and Mesoarchean microcontinents. Traces of Mesoarchean tonalite-trondhjemite-granodiorite (TTG)-type early crust were documented in all of the most ancient units of the Kola-Karelia continent. Ancient crust was revealed and dated in the Ranua and Iisalmi microcontinents, 3.5-3.4 Ga; Vodlozero and Khetolambina microcontinents, 3.25-3.15 Ga; Kuhmo-Segozero microcontinent, 3.0 Ga; Murmansk and Inari-Kola microcontinents, 2.93 Ga; and Kianta microcontinent, 2.83-2.81 Ga. In the older (>3.0 Ga) tectonic units and microcontinents, the ancient crust was possibly formed in brief bursts of endogenic activity. In younger microcontinents (3.0-2.93 Ga), these processes could continue until 2.8 and even 2.72 Ga. The tectonic settings in which early TTG crust has been produced are largely uncertain. The primary melt glassy inclusions with a glass phase in cores of prismatic zircon crystals from TTG gneisses provide evidence for the volcanic origin of gneiss protolith. Suggested genetic modeling of TTG-type complexes assumes that felsic K-Na melts with positive Eu anomaly are a product of dry high-temperature partial melting of the previously formed mafic-to-felsic crustal rocks and/or thick older TTG crust. Positive Eu anomaly in the eutectic is directly related to the predominance of plagioclase and K-feldspar in the melt. TTG-type crust melted to produce granitegranodiorite (GG) rocks. Earliest microcontinents are separated by Mesoarchean greenstone belts (mainly 3.05-2.85 Ga, in some cases up to 2.75 Ga), which are fragments of paleo-islandarc systems accreted to their margins: the Kolmozero-Voronya, Central Belomorian, Vedlozero-Segozero, Sumozero-Kenozero, and Tipasjärvi-Kuhmo-Suomussalmi belts; and the mature island arcs (microcontinents): Khetolambina and Kovdozero. These structural units are characterized by significant extent, close to rectilinear trend, localization along the boundaries between Archean microcontinents, and a specific set of petrotectonic assemblages (basalt-andesite-rhyolite, komatiite-tholeiite, and andesite-dacite associations). The recently discovered Meso-Neoarchean Belomorian eclogite province that is structurally linked with the Central Belomorian greenstone belt contains two eclogite associations distributed within TTG gneisses: the subduction-type Salma association and the Gridino eclogitized mafic dikes. The protolith of the Salma eclogites is thought to have been a sequence of gabbro, Fe-Ti gabbro, and troctolite, formed at ca. 2.9 Ga in a slow-spreading ridge (similar to the Southwest Indian Ridge). The main subduction and eclogite-facies events occurred between ca. 2.87 and ca. 2.82 Ga. Mafic magma injections into the crust of the active margin that led to formation of the Grigino dike swarm were associated with emplacement of a mid-ocean ridge in a subduction zone, beginning at ca. 2.87 Ga. Crustal delamination of the active margin and subsequent involvement of the lower crust in subduction 2.87-2.82 Ga ago led to high-pressure metamorphism of the Gridino dikes that reached eclogite-facies conditions during a collision event between 2.82 and 2.78 Ga. This collision resulted in consolidation of the Karelia, Kola, and Khetolamba blocks and formation of the Mesoarchean Belomorian accretionary-collisional orogen. To date, the subductionrelated Salma eclogites provide the most complete and meaningful information on the nature of plate tectonics in the Archean, from ocean-fl oor spreading to subduction and collision. The Kovdozero granite-greenstone terrain that separates the Khetolambina and Kuhmo-Segozero microcontinents is formed by TTG granitoids and gneisses hosting metasediments and metavolcanics of several greenstone belts, which belonged to the Parandovo-Tiksheozero island arc that existed from ca. 2.81 to 2.77 Ga. The Iringora greenstone belt includes the ophiolite complex of the same name with an age of 2.78 Ga. The collision of microcontinents resulted in the upward squeezing of the island arc and the obduction of its marginal portions onto surrounding structures. © 2015 The Geological Society of America. All rights reserved