Kondo effect in coupled quantum dots: a Non-crossing approximation study

The out-of-equilibrium transport properties of a double quantum dot system in the Kondo regime are studied theoretically by means of a two-impurity Anderson Hamiltonian with inter-impurity hopping. The Hamiltonian, formulated in slave-boson language, is solved by means of a generalization of the non-crossing approximation (NCA) to the present problem. We provide benchmark calculations of the predictions of the NCA for the linear and nonlinear transport properties of coupled quantum dots in the Kondo regime. We give a series of predictions that can be observed experimentally in linear and nonlinear transport measurements through coupled quantum dots. Importantly, it is demonstrated that measurements of the differential conductance ${\cal G}=dI/dV$, for the appropriate values of voltages and inter-dot tunneling couplings, can give a direct observation of the coherent superposition between the many-body Kondo states of each dot. This coherence can be also detected in the linear transport through the system: the curve linear conductance vs temperature is non-monotonic, with a maximum at a temperature $T^*$ characterizing quantum coherence between both Kondo states.Comment: 20 pages, 17 figure

Elevated lactate/albumin ratio as a novel predictor of in-hospital mortality in hospitalized cirrhotics

Introduction and Objectives: Novel predictors of prognosis in cirrhotic patients have been emerging in recent years and studies show that the lactate/albumin ratio can serve as an early prognostic marker in different patient groups. We aimed to uncover the clinical significance of the lactate/albumin ratio in hospitalized patients with acutely decompensated cirrhosis. Materials and Methods: A retrospective single-center cohort study was conducted in a tertiary medical center. Subjects included had an established diagnosis of liver cirrhosis and were admitted to the ICU or the Internal Medicine department with a clinical picture of acute-on-chronic liver failure between the years 2010 and 2021. The primary outcome was to assess the utility of the lactate/albumin ratio as a prognostic marker to predict mortality in hospitalized cirrhotic patients with acute-on-chronic hepatic failure. Results: Two hundred seventy-nine patients were included in this study. Univariate analysis revealed that mean WBC count, platelet/creatinine ratio, aspartate transaminase (AST), lactate, and MELD score were all significantly associated with the primary outcome. Multivariate analysis showed that the lactate/albumin ratio was the strongest statistically significant (p < 0.001) predictor of death during hospitalization - OR 13.196 (95% CI 3.6–48.3), followed by mean WBC count, MELD score, and serum lactate levels. A ROC curve was constructed, which resulted in an area under the curve (AUC) equal to 0.77. Crosstabs from the ROC showed a sensitivity of 66.7% and a specificity of 76.2% when the lactate/albumin ratio chosen as a cutoff was 0.9061 Conclusions: Elevated lactate/albumin ratio predicts in-hospital mortality in hospitalized cirrhotics with acute-on-chronic hepatic failure