ABSTRACT A closed-form analytical solution to rheological phenomena is obtained based on Hoek-Brown (HB) yield criterion and the generalized Bingham model. Once the circular tunnel is excavated, an initial plastic region is formed. When the total stresses fulfil the yield condition, the initial plastic region steps into the viscoplastic region, in which the displacement develops with time. The one-dimensional constitutive equation of the generalized Bingham model is transformed into a three-dimensional expression in polar coordinates by combining the plane strain condition. With the help of equilibrium differential equation, geometric equation and boundary condition, the stress and displacement in the initial plastic region can be expressed. At the moment of t, the stresses and displacements are described similar to the solutions of the elasto-plastic state. The stresses, strains and displacements after transformation can be expressed in the viscoplastic region. The proposed solution was verified by the closed-form solution of circular tunnels in elastic-brittle-plastic rock mass.

Abstract This paper deals with a deep circular tunnel excavated in infinite homogeneous and isotropic elasto-viscoplastic rock mass subjected to a hydrostatic initial stresses. The tunnel is divided into the initial plastic, viscoplastic, and elastic zones. By combining the generalized Bingham model with Mohr-Coulomb yield criteria, analytical solutions of the circular tunnel are derived with the consideration of non-associated flow rule and elasto-viscoplasticity. The initial plastic zone is defined as the instantaneous change of rock mass excavation. Based on the initial plastic zone, the stresses in viscoplastic zone are transferred to the deep surrounding rock with time due to the initial earth stresses. The results are compared with the elastic-brittle solution at static conditions, and the solutions of this paper are validated. Moreover, the presented results shows that the stress and displacement of the surrounding rock varies with time, and the solutions can be obtained at different instants of time.

ABSTRACT Objective: The aim was to characterize blood glucose fluctuations in patients with fulminant type 1 diabetes (FT1DM) at the stable stage using continuous blood glucose monitoring systems (CGMSs). Subjects and methods: Ten patients with FT1DM and 20 patients with classic type 1 diabetes mellitus (T1DM) (the control group) were monitored using CGMSs for 72 hours. Results: The CGMS data showed that the mean blood glucose (MBG), the standard deviation of the blood glucose (SDBG), the mean amplitude glycemic excursions (MAGE), the blood glucose areas and the percentages of blood glucose levels below 13.9 mmol/L were similar between the two groups. However, the percentage of blood glucose levels below 3.9 mmol/L was significantly higher in the FT1DM group compared to the T1DM group (p < 0.05). The minimum (Min) blood glucose level in the FT1DM group was significantly lower than that of the T1DM group (p < 0.05). Patients with FT1DM had severe dysfunction of the islet beta cells and alpha cells compared to patients with T1DM, as indicated by lower C-peptide values and higher glucagon/C-peptide values. Conclusion: In conclusion, patients with FT1DM at the stable stage were more prone to hypoglycemic episodes as recorded by CGMSs, and they had a greater association with severe dysfunction of both the beta and alpha islet cells compared to patients with T1DM.

Resumo Fundamentos: A antraciclina gera uma disfunção ventricular esquerda progressiva associada a um prognóstico ruim. Objetivos: O propósito deste estudo foi avaliar se a análise layer específico de strain poderia avaliar disfunção ventricular esquerda subclínica após exposição a antraciclina. Métodos: Foram inscritos quarenta e dois sobreviventes tratados com antraciclina por linfoma não Hodgkin de células B grandes, de 55,83 ± 17,92 anos (grupo de quimioterapia) e 27 voluntários saudáveis, de 51,39 ± 13,40 anos (grupo controle). A dose cumulativa de epirrubicina no grupo de quimioterapia foi de 319,67 ± 71,71 mg/m2. O tempo desde a última dose de epirrubicina até o exame ecocardiográfico foi de 52,92 ± 22,32 meses. Analisaram-se o strain longitudinal global (GLS), o circunferencial (GCS) e o strain radial (GRS), os valores das camadas subendocárdica, média e subepicárdica so strain longitudinal (LS-ENDO, LS-MID, LS-EPI) e do strain circunferencial (CS-ENDO, CS-MID, CS-EPI). O gradiente de strain transmural foi calculado como a diferença no strain sistólico pico entre as camadas subendocárdicas e subepicárdicas. Um valor de p < 0,05 foi considerado significativo. Resultados: Os parâmetros convencionais da função sistólica e diastólica não mostraram diferenças significativas entre dois grupos. Comparados aos controles, os pacientes apresentaram GCS e GLS significativamente menores. A análise de speckle tracking multi-layer mostrou uma redução significativa no strain circunferencial da camada subendocárdica, o gradiente transmural CS e o strain longitudinal das três camadas. Em contraste, os dois grupos não diferiram no gradiente de strain longitudinal transmural e de strain radiais. Conclusões: Provou-se a deterioração preferencial do strain subendocárdico em sobreviventes de longa duração após exposição à antraciclina. O ecocardiograma de speckle tracking multi-layer pode facilitar o acompanhamento longitudinal dessa coorte de pacientes em risco. (Arq Bras Cardiol. 2018; 110(3):219-228)

Abstract Background: Anthracycline generates progressive left ventricular dysfunction associated with a poor prognosis. Objectives: The purpose of this study was to evaluate whether layer-specific strain analysis could assess the subclinical left ventricular dysfunction after exposure to anthracycline. Methods: Forty-two anthracycline-treated survivors of large B-cell non-Hodgkin lymphoma, aged 55.83 ± 17.92 years (chemotherapy group) and 27 healthy volunteers, aged 51.39 ± 13.40 years (control group) were enrolled. The cumulative dose of epirubicin in chemotherapy group was 319.67 ± 71.71mg/m2. The time from last dose of epirubicin to the echocardiographic examination was 52.92 ± 22.32 months. Global longitudinal (GLS), circumferential (GCS) and radial strain (GRS), subendocardial, mid and subepicardial layer of longitudinal (LS-ENDO, LS-MID, LS-EPI) and circumferential strain (CS-ENDO, CS-MID, CS-EPI) values were analyzed. Transmural strain gradient was calculated as differences in peak systolic strain between the subendocardial and subepicardial layers. A value of p < 0.05 was considered significant. Results: Conventional parameters of systolic and diastolic function showed no significant difference between two groups. Compared with controls, patients had significantly lower GCS and GLS. Multi-layer speckle tracking analysis showed significant reduction of circumferential strain of subendocardial layer, transmural CS gradient and longitudinal strain of all three layers. In contrast, the two groups did not differ in transmural longitudinal strain gradient and radial strains. Conclusions: It proved the preferential impairment of subendocardial deformation in long-term survivors after exposure to anthracycline. Multi-layer speckle tracking echocardiography might facilitate the longitudinal follow-up of this at-risk patient cohort.