No abstract

The electromagnetically induced transparency (EIT) observations in two Λ-systems of 87 Rb atom, |5 2 S 1/2 F = 1 → |5 2 P 3/2 F = 1 ← |5 2 S 1/2 F = 2 and |5 2 S 1/2 F = 1 → |5 2 P 3/2 F = 2 ← |5 2 S 1/2 F = 2 , have been investigated in detail and the results are found consistent with our proposed theoretical models. The second Λ-system provides EIT signal with higher magnitude than the first system, both in absence and in presence of an applied magnetic field. The observed steeper slope of the EIT signal in presence of the magnetic field can enable one to achieve tight frequency locking of lasers using these EIT signals.

A Λ-system in D2 line transition of the 87 Rb atom has been investigated for quantum interference effects for different configurations of coupling field. With a travelling wave coupling field (copropagating with probe field), the probe beam shows the earlier known electromagnetically induced transparency (EIT) effect at the resonance. With a standing wave coupling field (which is co-and counter-propagating with probe beam), the probe EIT gets transformed into an electromagnetically induced absorption (EIA). A variation in coupling beam power has shown that, at high coupling power, EIA signals have much larger amplitude and slope than those of EIT signals with and without applied magnetic field. These EIA signals can be useful for tight laser frequency locking and optical switching.

Muscles are the only tissues in the body that have the ability to contract and hence move the other parts of the body. The strength of any given muscle, in terms of force exerted on the skeleton depends upon length, shortening speed, cross-sectional area, sarcomere length, myosin isoforms and neural activation of motor units. Fatigue is a reversible physiological state in which there is an objective reduction in the performance or it's absence resulting from continuous or prolonged activity. The degree, duration and type of work are the important factors that affect the performance and onset of fatigue. To correlate body mass index (BMI) and muscle fatigability in young healthy adults. This cross sectional study included 100 apparently healthy young adults, both males and females between 18-24 years of age and without a history of alcohol or tobacco consumption, history of any cardiovascular disorders or diabetes mellitus and any drug history like corticosteroids, beta blockers. and underwent fatigue test using Mosso's Ergograph and the work done (Kgm) was calculated and correlated with body mass index. The results showed a strong positive correlation between Body Mass Index and work done(r=1) which was found to be statistically significant (p<0.05). Moreover, The results showed a very strong positive correlation(r=1) between different categories of Body Mass Index and the amount of work done by the exercising muscle, but the results were statistically non significant (p<0.05) in all the sub categories of body mass index. A strong positive correlation between Body Mass Index and amount of work done by the exercising muscle suggests that the level of fatigueness in an individual is related to his/her nutritional status and physical fitness.