Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On conditions of negativity of friction resistance for non-stationary
  modes of blood flow and possible mechanism of affecting of environmental
  factors on energy effectiveness of cardio-vascular system functioning   It is shown that initiated by action of molecular viscosity impulse flow,
directed usually from the moving fluid to limiting it solid surface, can, under
certain conditions, turn to zero and get negative values in the case of
non-stationary flow caused by alternating in time longitudinal (along the pipe
axis) pressure gradient. It is noted that this non-equilibrium mechanism of
negative friction resistance in the similar case of pulsating blood flow in the
blood vessels, in addition to the stable to turbulent disturbances swirled
blood flow structure providing, can also constitute hydro-mechanical basis of
the observed but not explained yet paradoxically high energy effectiveness of
the normal functioning of the cardio-vascular system (CVS). We consider
respective mechanism of affecting on the stability of the normal work of CVS by
environmental variable factors using shifting of hydro-dynamic mode with
negative resistance realization range boundaries and variation of linear
hydro-dynamic instability leading to the structurally stable swirled blood flow
organization.

27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
4
The categories of this paper are: cond-mat
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
31
The categories of this paper are: ao-sci
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
19
The categories of this paper are: eess
2
The categories of this paper are: math
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin