|Chaos refers to a phenomenon whose behavior is extremely complex, erratic and
unstable and is incapable of predicting the state of the far future, despite
the generation system of the phenomenon is based on a set of firm rules (deterministic rules).
There are 5 characteristics that make up the properties of chaos:
|Sensitive to initial values (replication by
controling initial values is very rare)
|Hold a wide power spectrum with no distinct
shape in frequency components
|Neighboring orbits passing the subspace of the attractor
are approximately in the same direction
|Correlation function rapidly becomes zero along with time
| Largest Lyapunov exponent is positive
|Have a non-integer fractal dimension
|Characteristics of 2, 4, 5 and 6 are also found in random signals. The characteristic of 3
is also found in quasi-periodically signals.
|Cannon's "homeostasis" is said the basic principle in
physiology that pursues the principles of life phenomena.
Homeostatis is a term coined from the Greek words of homeo meaning "the same" and statis meaning "the state" by Walter B. Cannon, an American physiologist, and refers to the function that maintains the composition and
the physical conditions of the living body at a constant state. It has been said that homeostatis
should be preserved for a living body to maintain life and there
was an automatic adjustment feature made from a negative feedback circuit within the body.
When applying the concept of homeostatis to vital signs (such as heart rate, respiration, blood pressure and body temperature
whose are directly related to the maintenance of life), it was
thought that there was a feedback mechanism in a human body, which compensate
for any outside disturbance that causes deviation from a constant
state (normal values), and the more these values were stable, the
more the control system of a living body was functioning well . However,
the fact is even when a human is lying still, the beating interval of
his/her heart is not constant, and shows considerable erratic fluctuations (heart-rate fluctuation). Respiration, blood pressure and body temperature are
also the same. About heart-rate fluctuations, It is known that elder
humans and sick humans have less fluctuations.
In the field of physiology, from the mid of the 1980's, there was a flurry of reports indicating
that biological signals such as heart-rate fluctuations and brain waves may be chaotic.
And a review of chaos (T. Elbert, W. J. Ray, Z. Kowalik, J. E. Skinner, K. E. Graf and N.
Birbaumer, Physiol. Rev. 74 (1994) 1) was published in Physiological Review, an authoritative magazine in the field of physiology
. In the field of physiology, research
on chaos is getting common .
of the human body is called vital signs and include body temperature, blood pressure, pulse rate, etc.
As the vital sign to use, we measure the amount of blood flowing in the vessels at the
fingertip, and construct time-series waves from it. The advantage of
using a fingertip rather than a heart, is that fingertip pulse waves
contain more information such as the nerve system than heart pulse
waves. This is because fingertips locate at the end of the body.
The measured vital signs show so complex (chaotic) behavior that we
use nonlinear (chaos) analysis and calculate Lyapunov exponents from
the measured waves.
|It is said that physical immunity is important for human beings to maintain
health, and declining in physical immunity cause various illnesses.
We defend ourselves against declining in physical immunity by many
ways as proper eating habits, adequate rest, medicine and physical
exercise. On the other hand, even though mental immunity is also extremely important for human
beings, there was no way to measure our mental immunity in the
past. However, as the result of our psychological and
bio-informatics research, we found the value of Lyapunov exponents
of the fingertip plethysmogram and the mental immunity are closely related
as described below.
|Mental immunity refers to human's adaptability, communication
skill, ability of self-expression, flexibility of the mind, etc. against changes in the
environment we face throughout our lives. To maintain our lives, we human beings
skillfully manage various changes, encounters and attacks through
adaptation, engagement, handling and self-expression. Those are
exactly the effectiveness of the mental immunity. Mental immunity is
one of the most important index for the human life. Mental immunity
dynamically changes time by time based on his/her condition and emotion such as delight, anger, sorrow and pleasure. The mental immunity
dynamically fluctuates in occasions such as, for example, when you
concentrate on work or lose concentration, when you are strongly motivated, when you
are uncomfortable to communicate with a certain type of people or when you
enjoy communication with people you like. It can be said that he/she
has high mental immunity when one can motivate and drive oneself to
perform a difficult task. The value of mental immunity (the
Lyapunov exponents value) is used to fluctuate dynamically.
Permanently high or permanently low state of mental immunity with no fluctuation
can be said an abnormal condition for human being. Excessive tension or stress will show a continuous high value. On other hand, state of dementia caused by depression or aging will show a continuous low value.
Up to now, we have reported a various of researches about
relationship between the mental immunity and the Lyapunov exponents.
Among these are, correlation between lower values in the Lyapunov exponents
and lesser communication skill caused by aging or progression of
dementia, relationship between the Lyapunov exponents and work errors, verification of
the mental turning point of 3 year old children seen in worldwide in
respect to the Lyapunov exponents values. As the result of our
researches, it can be said for human beings that our mental immunity
is desirable to have constantly moderate fluctuation regardless of the age.
Just as one becomes ill when one lose physical immunity, The mental immunity may be considered
as a synonymous word of the "vitality of the mind" whose
term was a vague sense up to now. The "vitality of the mind"
have not been able to quantitatively measure, but now we believe it can be grasped by measuring the "fluctuation"
using the Lyapunov exponents.
|Our prime purpose of research is to establish ways that allow us to scientifically
explore human life and body. By focusing on the chaotic characteristics of human beings, we have
now two major research themes such as the relationship between cognitive psychology
and fluctuation of bio-information measured by the Lyapunov
exponents values, and relationship between visual impressions and
presented picture image. In order to fulfill our research, we have adopted data mining and text mining as methods for analyzing experiment and survey data.
For the first theme, we have developed a system that calculates and displays fluctuation values of pulse waves using chaos analysis,
and also a graphical presentation system and a database system for further
grasping the fluctuation in long term. These systems are used to conduct researches
to explore relationship between bio-information and various fields
such as the anxieties or depressions of working people, the growth of children,
affection of mothers/problem behavior of children, human emotion
caused by scent, music and laugh, and so on. We also have a plan to develop a compact
device that is user friendly and handy to carry so that anyone and
at anywhere can measure pulse waves. Our plan of development and
sales of such a device is with manufacturing partners and sales
partners. For the accumulation of data, our plan is to develop a
database in Internet with companies who have rich of experience and
skill about data security. Cellular phones is also one of our target
The research of our second theme is focused on human's sight. we
pursue the way to measure from image data how much these images give
human good impression. We conducted researches on relationship
between human's preferable impression and the fractal dimensions of
presented picture images.
With our two research themes, we expect our researches will be applied
in variety of fields including welfare/nursing care, psychotherapy, child growth and education.