Acceleration waves and oscillating gas bubbles modelled by rational extended thermodynamics

The study of acceleration waves for a rarefied polyatomic gas is carried out in planar, cylindrical and spherical geometry referring to the rational extended thermodynamics theory with 14 moments. The case of a rarefied monatomic gas is determined as a limit case, and the role of geometry and molecular degrees of freedom is investigated. In addition, the behaviour of an acceleration wave travelling inside an oscillating gas bubble is modelled by the 14-moment PDE system under adiabatic condition. We show that dissipation combined with hyperbolicity tends to inhibit shock formation, and that the dynamic pressure cannot be zero inside the oscillating bubble. This fact can produce observable effects even in the Navier–Stokes approximation, if the gas exhibits high bulk viscosity.

Nutritional patterns in elderly patients with dementia of Alzheimer type

Body weight and some nutritional serum parameters (albumin, urea nitrogen, creatinine, glycemia, hemoglobin, total cholesterol, triglycerides, potassium) were analyzed in 44 subjects aged over 60 in order to evaluate weight loss and its possible link with the progression of dementia. Patients were consecutively admitted to our Day Hospital with the complaint of psychogeriatric symptoms. They all were living at home, no one presented risk factors for malnutrition and their cognitive impairment did not exceed the 4th degree of GDS (Global Deterioration Scale). Subjects were divided into two groups on the basis of diagnosis at discharge: (i) Possible or probable dementia of Alzheimer type (30 subjects, mean age 72.1 +/- 5.9 years), (ii) Age-associated memory impairment (14 subjects, mean age 73.6 +/- 6.2 years). One year later, a second control of body weight and nutritional parameters was performed. Differences between these latter measures versus the initial values were not significant when analyzed in the total group of demented patients or in the subgroups with different degree of cognitive impairment and physical activity. A possible hypothesis to explain the absence of differences among groups is that the caregivers were very carefully looking after all the patients examined.