Theoretical backgrounds of durability analysis by normalized equivalent stress functionals

Generalized durability diagrams and their properties are considered for a material under a multiaxial loading given by an arbitrary function of time. Material strength and durability under such loading are described in terms of durability, safety factor and normalized equivalent stress. Relations between these functionals are analysed. We discuss some material properties including time and load stability, self-degradation (ageing), and monotonic damaging. Phenomenological strength conditions are presented in terms of the normalized equivalent stress. It is shown that the damage based durability analysis is reduced to a particular case of such strength conditions. Examples of the reduction are presented for some known durability models. The approach is applicable to the strength and durability description at creep and impact loading and their combination

Urinary tract infections in pregnancy (review)

Urinary tract infections in pregnancy are common in obstetric practice. This urological pathology is recorded in about every third pregnant woman. There is no trend forward to decline the disease prevalence. Moreover, the number of pregnant women with kidney diseases has increased 4 times over the last 20 years. The best practice for diagnosis of urinary tract infections is urine culture test, which is considered to be the most reliable and accurate diagnostic. According to Order No. 572n by the Ministry of Public Health of the Russian Federation dated 01.11.2012, the procedure is carried out for all pregnant women started from 14 weeks of pregnancy. The necessity for early diagnostics and treatment of urinary tract infections in pregnancy is obvious, since there is a risk of the infection negative impact on a mother and a fetus, course of pregnancy, childbirth and postpartum period. Antibacterial therapy is a method of choice and should be administrated taking into account criteria of safety and tolerability (Food And Drug Administration criteria). Taking into account that antibiotics administration is often empiric, the constant dynamic monitoring of the structure of uropathogens and antimicrobial resistance having specific local features is required

Gestational weight galns in the first trimesrter and risk of pathological birth weight deviations

The cohort study of 467 pregnant women. Analysis has indicated impact of body weight gains in the first trimester on antenatal fetal growth. Low body weight gain or weight loss in early pregnancy were associated with increased risk of small for gestational age. And on the contrary, a fast weight gain with accumulation of a fatty component was associated with the subsequent macrosomia

Theoretical backgrounds of durability analysis by normalized equivalent stress functionals

Generalized durability diagrams and their properties are considered for a material under a multiaxial loading given by an arbitrary function of time. Material strength and durability under such loading are described in terms of durability, safety factor and normalized equivalent stress. Relations between these functionals are analysed. We discuss some material properties including time and load stability, self-degradation (ageing), and monotonic damaging. Phenomenological strength conditions are presented in terms of the normalized equivalent stress. It is shown that the damage based durability analysis is reduced to a particular case of such strength conditions. Examples of the reduction are presented for some known durability models. The approach is applicable to the strength and durability description at creep and impact loading and their combination