Eastern Arctic Ocean Diapycnal Heat Fluxes through Large Double-Diffusive Steps

The diffusive layering (DL) form of double-diffusive convection cools the Atlantic Water (AW) as it circulates around the Arctic Ocean. Large DL steps, with heights of homogeneous layers often greater than 10 m, have been found above the AW core in the Eurasian Basin (EB) of the eastern Arctic. Within these DL staircases, heat and salt fluxes are determined by the mechanisms for vertical transport through the high-gradient regions (HGRs) between the homogeneous layers. These HGRs can be thick (up to 5 m and more) and are frequently complex, being composed of multiple small steps or continuous stratification. Microstructure data collected in the EB in 2007 and 2008 are used to estimate heat fluxes through large steps in three ways: using the measured dissipation rate in the large homogeneous layers; utilizing empirical flux laws based on the density ratio and temperature step across HGRs after scaling to account for the presence of multiple small DL interfaces within each HGR; and averaging estimates of heat fluxes computed separately for individual small interfaces (as laminar conductive fluxes), small convective layers (via dissipation rates within small DL layers), and turbulent patches (using dissipation rate and buoyancy) within each HGR. Diapycnal heat fluxes through HGRs evaluated by each method agree with each other and range from ~2 to ~8 W m−2, with an average flux of ~3–4 W m−2. These large fluxes confirm a critical role for the DL instability in cooling and thickening the AW layer as it circulates around the eastern Arctic Ocean

Ocean stratification and sea-ice cover in Barents and Kara seas modulate sea-air methane flux: satellite data

The diverse range of mechanisms driving the Arctic amplification and global climate are not completely understood and, in particular, the role of the greenhouse gas methane (CH4) in the Arctic warming remains unclear. Strong sources of methane at the ocean seabed in the Barents Sea and other polar regions are well documented. Nevertheless, some of those publications suggest that negligible amounts of methane fluxed from the seabed enter the atmosphere, with roughly 90% of the methane consumed by bacteria. Most in situ observations are taken during summer, which is favorable for collecting data but also characterized by a stratified water column. We present perennial observations of three Thermal IR space-borne spectrometers in the Arctic between 2002 and 2020. According to estimates derived from the data synthesis ECCO (Estimating the Circulation and Climate of the Ocean), in the ice-free Barents Sea the stratification in winter weakens after the summer strong stability. The convection, storms, and turbulent diffusion mix the full-depth water column. CH4 excess over a control area in North Atlantic, measured by three sounders, and the oceanic Mixed Layer Depth (MLD) both maximize in winter. A significant seasonal increase of sea-air exchange in ice-free seas is assumed. The amplitude of the seasonal methane cycle for the Kara Sea significantly increased since the beginning of the century. This may be explained by a decline of ice concentration there. The annual CH4 emission from the Arctic seas is estimated as 2/3 of land emission. The Barents/Kara seas contribute between 1/3 and 1/2 into the Arctic seas annual emission

Fluctuating Atlantic inflows modulate Arctic atlantification

Enhanced warm, salty subarctic inflows drive high-latitude atlantification, which weakens oceanic stratification, amplifies heat fluxes, and reduces sea ice. In this work, we show that the atmospheric Arctic Dipole (AD) associated with anticyclonic winds over North America and cyclonic winds over Eurasia modulates inflows from the North Atlantic across the Nordic Seas. The alternating AD phases create a “switchgear mechanism.” From 2007 to 2021, this switchgear mechanism weakened northward inflows and enhanced sea-ice export across Fram Strait and increased inflows throughout the Barents Sea. By favoring stronger Arctic Ocean circulation, transferring freshwater into the Amerasian Basin, boosting stratification, and lowering oceanic heat fluxes there after 2007, AD+ contributed to slowing sea-ice loss. A transition to an AD− phase may accelerate the Arctic sea-ice decline, which would further change the Arctic climate system.acceptedVersio

Weakening of cold halocline layer exposes sea ice to oceanic heat in the eastern Arctic Ocean

A 15-yr duration record of mooring observations from the eastern (>70°E) Eurasian Basin (EB) of the Arctic Ocean is used to show and quantify the recently increased oceanic heat flux from intermediate-depth (~150–900 m) warm Atlantic Water (AW) to the surface mixed layer and sea ice. The upward release of AW heat is regulated by the stability of the overlying halocline, which we show has weakened substantially in recent years. Shoaling of the AW has also contributed, with observations in winter 2017–18 showing AW at only 80 m depth, just below the wintertime surface mixed layer, the shallowest in our mooring records. The weakening of the halocline for several months at this time implies that AW heat was linked to winter convection associated with brine rejection during sea ice formation. This resulted in a substantial increase of upward oceanic heat flux during the winter season, from an average of 3–4 W m−2 in 2007–08 to >10 W m−2 in 2016–18. This seasonal AW heat loss in the eastern EB is equivalent to a more than a twofold reduction of winter ice growth. These changes imply a positive feedback as reduced sea ice cover permits increased mixing, augmenting the summer-dominated ice-albedo feedback

On the seasonal cycles observed at the continental slope of the Eastern Eurasian Basin of the Arctic Ocean

The Eurasian Basin (EB) of the Arctic Ocean is subject to substantial seasonality. We here use data collected between 2013 and 2015 from six moorings across the continental slope in the eastern EB and identify three domains, each with its own unique seasonal cycle: 1) The upper ocean (<100 m), with seasonal temperature and salinity differences of Δθ = 0.16°C and ΔS = 0.17, is chiefly driven by the seasonal sea ice cycle. 2) The upper-slope domain is characterized by the influence of a hydrographic front that spans the water column around the ~750-m isobath. The domain features a strong temperature and moderate salinity seasonality (Δθ = 1.4°C; ΔS = 0.06), which is traceable down to ~600-m depth. Probable cause of this signal is a combination of along-slope advection of signals by the Arctic Circumpolar Boundary Current, local wind-driven upwelling, and a cross-slope shift of the front. 3) The lower-slope domain, located offshore of the front, with seasonality in temperature and salinity mainly confined to the halocline (Δθ = 0.83°C; ΔS = 0.11; ~100–200 m). This seasonal cycle can be explained by a vertical isopycnal displacement (ΔZ ~ 36 m), arguably as a baroclinic response to sea level changes. Available long-term oceanographic records indicate a recent amplification of the seasonal cycle within the halocline layer, possibly associated with the erosion of the halocline. This reduces the halocline’s ability to isolate the ocean surface layer and sea ice from the underlying Atlantic Water heat with direct implications for the evolution of Arctic sea ice cover and climate

Quantum Phase Transition in Frustrated Two-Dimensional Antiferromagnets

We study frustrated, two-dimensional, quantum antiferromagnets in the vicinity of a quantum transition from a non-collinear, magnetically-ordered ground state to a quantum disordered phase. The general scaling properties of this transition are described. A detailed study of a particular field-theoretic model of the transition, with bosonic spin-1/2 spinon fields, is presented. Explicit universal scaling forms for a variety of observables are obtained and the results are compared with numerical data on the spin-1/2 triangular antiferromagnet. Universal properties of an alternative field-theory, with confined spinons, are also briefly noted.Comment: 51 pages, REVTEX 3.0, 5 uuencoded EPS figures appended, YCTP-xxz

Universal Magnetic Properties of La2−δSrδCuO4La_{2-\delta} Sr_{\delta} Cu O_4 at Intermediate Temperatures

We present the theory of two-dimensional, clean quantum antiferromagnets with a small, positive, zero temperature ($T$) stiffness $\rho_s$, but with the ratio $k_B T / \rho_s$ arbitrary. Universal scaling forms for the uniform susceptibility ($\chi_u$), correlation length($\xi$), and NMR relaxation rate ($1/T_1$) are proposed and computed in a $1/N$ expansion and by Mont\'{e}-Carlo simulations. For large $k_B T/\rho_s$, $\chi_u (T)/T$ and $T\xi(T)$ asymptote to universal values, while $1/T_{1}(T)$ is nearly $T$-independent. We find good quantitative agreement with experiments and some numerical studies on $La_{2-\delta} Sr_{\delta} Cu O_4$.Comment: 14 pages, REVTEX, 1 postscript figure appende

Аутотрансплантация почки – метод лечения поражения мочеточника в урологической и онкологической практике

The first successful kidney autotransplantation was performed in 1902. The technique has undergone several changes since then. The indications and surgical technique are presented in this literature review. Kidney autotransplantation is the treatment of choice for preserving renal function. Three clinical observations on the use of kidney autotransplantation in urological and oncological practice are described: a patient after iatrogenic ureteral injury and two patients with primary retroperitoneal tumor. Literature analysis and clinical observations from urological and oncological practice show that kidney autotransplantation could be safely used for strictly selected indications.Первая аутотрансплантация почки была выполнена в 1902 г., с этого времени техника ее выполнения претерпела ряд изменений. В литературном обзоре представлены показания и хирургическая техника. Аутотрансплантация почки является методом выбора лечения, направленного на сохранение почечной функции. Описаны 3 клинических наблюдения по применению аутотрансплантации почки в урологической и онкологической практике: пациент после ятрогенного повреждения мочеточника и два пациента с неорганной опухолью забрюшинного пространства. Анализ литературы и клинические наблюдения из урологической и онкологической практики показывают возможность безопасного применения аутотрансплантации почки по строго выбранным показаниям

Theory of Two-Dimensional Quantum Heisenberg Antiferromagnets with a Nearly Critical Ground State

We present the general theory of clean, two-dimensional, quantum Heisenberg antiferromagnets which are close to the zero-temperature quantum transition between ground states with and without long-range N\'{e}el order. For N\'{e}el-ordered states, `nearly-critical' means that the ground state spin-stiffness, $\rho_s$, satisfies $\rho_s \ll J$, where $J$ is the nearest-neighbor exchange constant, while `nearly-critical' quantum-disordered ground states have a energy-gap, $\Delta$, towards excitations with spin-1, which satisfies $\Delta \ll J$. Under these circumstances, we show that the wavevector/frequency-dependent uniform and staggered spin susceptibilities, and the specific heat, are completely universal functions of just three thermodynamic parameters. Explicit results for the universal scaling functions are obtained by a $1/N$ expansion on the $O(N)$ quantum non-linear sigma model, and by Monte Carlo simulations. These calculations lead to a variety of testable predictions for neutron scattering, NMR, and magnetization measurements. Our results are in good agreement with a number of numerical simulations and experiments on undoped and lightly-doped $La_{2-\delta} Sr_{\delta}Cu O_4$.Comment: 81 pages, REVTEX 3.0, smaller updated version, YCTP-xxx

Retinoblastoma seeds: Impact on American Joint Committee on Cancer clinical staging

Aim To investigate whether the American Joint Committee on Cancer (AJCC) clinical category cT2b needs to be subclassified by the type and distribution of retinoblastoma (RB) seeding. Methods Multicentre, international registry-based data were collected from RB centres enrolled between January 2001 and December 2013. 1054 RB eyes with vitreous or subretinal seeds from 18 ophthalmic oncology centres, in 13 countries within six continents were analysed. Local treatment failure was defined as the use of secondary enucleation or external beam radiation therapy (EBRT) and was estimated with the Kaplan-Meier method. Results Clinical category cT2b included 1054 eyes. Median age at presentation was 16.0 months. Of these, 428 (40.6%) eyes were salvaged, and 430 (40.8%) were treated with primary and 196 (18.6%) with secondary enucleation. Of the 592 eyes that had complete data for globe salvage analysis, the distribution of seeds was focal in 143 (24.2%) and diffuse in 449 (75.8%). The 5-year Kaplan-Meier cumulative globe-salvage (without EBRT) was 78% and 49% for eyes with focal and diffuse RB seeding, respectively. Cox proportional hazards regression analysis confirmed a higher local treatment failure risk with diffuse seeds as compared with focal seeds (hazard rate: 2.8; p<0.001). There was insufficient evidence to prove or disprove an association between vitreous seed type and local treatment failure risk(p=0.06). Conclusion This international, multicentre, registry-based analysis of RB eyes affirmed that eyes with diffuse intraocular distribution of RB seeds at diagnosis had a higher risk of local treatment failure when compared with focal seeds. Subclassification of AJCC RB category cT2b into focal vs diffuse seeds will improve prognostication for eye salvage.Fil: Tomar, Ankit Singh. New York Eye Cancer Center; Estados UnidosFil: Finger, Paul T.. New York Eye Cancer Center; Estados UnidosFil: Gallie, Brenda. University Of Toronto. Hospital For Sick Children; CanadáFil: Kivelä, Tero. University of Helsinki; Finlandia. Helsinki University Hospital; FinlandiaFil: Mallipatna, Ashwin. University Of Toronto. Hospital For Sick Children; Canadá. Narayana Nethralaya; IndiaFil: Zhang, Chengyue. Beijing Children's Hospital; ChinaFil: Zhao, Junyang. Beijing Children's Hospital; ChinaFil: Wilson, Matthew. University of Tennessee; Estados UnidosFil: Brennan, Rachel. St Jude Children's Research Hospital; Estados UnidosFil: Burges, Michala. University of Tennessee; Estados UnidosFil: Kim, Jonathan. Keck Medical School of the University of Southern California; Estados UnidosFil: Berry, Jesse L.. Children's Hospital Los Angeles; Estados UnidosFil: Jubran, Rima. Childrens Hospital Society of Los Angeles; Estados UnidosFil: Khetan, Vikas. Vitreo Retinal Services; IndiaFil: Ganeshan, Suganeswari. Vitreo Retinal Services; IndiaFil: Yarovoy, Andrey. Fyodorov Eye Microsurgery Federal State Institution; RusiaFil: Yarovaya, Vera. Fyodorov Eye Microsurgery Federal State Institution; RusiaFil: Kotova, Elena. Fyodorov Eye Microsurgery Federal State Institution; RusiaFil: Volodin, Denis. Fyodorov Eye Microsurgery Federal State Institution; RusiaFil: Yousef, Yacoub. King Hussein Cancer Center; JordaniaFil: Nummi, Kalle. University of Helsinki; Finlandia. Helsinki University Hospital; FinlandiaFil: Ushakova, Tatiana L.. N.N. Blokhin Russian Cancer Research Center; Rusia. Russian Academy of Postgraduate Medical Education; RusiaFil: Yugay, Olga V.. N.N. Blokhin Russian Cancer Research Center; RusiaFil: Polyakov, Vladimir G. N.N. Blokhin Russian Cancer Research Center; Rusia. Russian Academy of Sciences; RusiaFil: Ramirez Ortiz, Marco Antonio. Hospital Infantil de Mexico Federico Gomez; MéxicoFil: Esparza Aguiar, Elizabeth. Hospital Infantil de Mexico Federico Gomez; MéxicoFil: Chantada, Guillermo Luis. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Schaiquevich, Paula Susana. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Fandiño, Adriana Cristina. Gobierno de la Ciudad de Buenos Aires. Hospital de Pediatría "Juan P. Garrahan"; ArgentinaFil: Yam, Jason C.. The Chinese University of Hong Kong Faculty of Medicine; Hong Kon