ABSTRACT
This paper presents a numerical study of the structural parameters of a one-dimensional chain of three dust particles levitating in the near-electrode layer of an rf discharge or in the stratum of a dc discharge. The model considers the motion of dust particles under the action of gravity, external electric field, the Coulomb repulsion, and the electrostatic force from the space charge surrounding the dust particles. Particular attention is paid to the effect of plasma polarization around dust particles and the wake formation under the action of the external electric field. Calculations showed that the charge of the first dust particle in the chain and the total charge of the entire chain, as well as the length of the chain, grow linearly with the external electric field strength. Obtained data are in qualitative agreement with the experimental and numerical data presented in the literature. It was shown that for a certain large value of the external electric field, the charge of the third dust particle is the smallest of all the particles in the chain. It was found that with an increase in the mean value of the external electric field, the chain of dust particles is displaced as a whole in the direction opposite to the action of the electrostatic force on them.
ABSTRACT
A self-consistent model of plasma polarization around an isolated micron-sized dust particle under the action of an external electric field is presented. It is shown that the quasineutral condition is fulfilled and the formed volume charge totally screens the dust particle. The ion focusing and wake formation behind the dust particle are demonstrated for different ion mean free paths and the external electric fields. It is obtained that at low values of the external electric field the trapped ions play the main role in the screening of the dust particle charge. For high external electric fields, the density of trapped ions decreases and the dust particle is screened mainly by the free ions.
ABSTRACT
AIM: To compare clinical and morphological results of treatment of ischemic stroke in three groups of patients which differed by the forms and duration of an antioxidant therapy. MATERIAL AND METHODS: A randomized clinical trial was performed in 8 vascular centers of the Russian Federation in 2010-2014. It included 373 patients with ischemic stroke in the carotid territory. Patients were randomized into 3 groups to receive different regimens of antioxidant therapy as an adjunct to standard therapy: control group (ascorbic acid; 132 patients); cytoflavin (20 ml per day for 10 days; 133 patients); cytoflavin (the dose was decreased to 10 ml per day from 11th to 20th day) (108 patients). Patient's condition was assessed in 1, 10 and 21 day by a complex of clinical, laboratory and instrumental methods. RESULTS AND CONCLUSION: The analysis of CT in 1th and 21th day revealed a significant 1,5-1,7- fold decrease in the cerebral ischemic lesion in both groups treated with cytoflavin with no significant morphologic changes in the ascorbic acid group. The percentage of patients with ischemic lesion, increased during days 1-21, was 2-fold higher in the ascorbic acid group compared to cytoflavin groups. Morphologic changes were correlated with clinical variables and outcome. In patients with ≥14 points on NIH scale on admission, prolonged 20 day cytoflavin therapy was associated with a more prominent improvement of neurologic, functional and cognitive status compared to 10-day cytoflavin infusion. No differences in clinical variables were observed in patients with mild symptoms (<14 points on NIH scale on admission) receiving cytoflavin for 10 and 20 days.
