Ranjan Sengupta

Multiplicity characteristics of heavy-ion interactions at 4.5GeV/yc per nucleon

Abstract This paper presents exhaustive, new data on the shower and compound multiplicity charactersties of 24 Mg-emulsion and 12 C-emulsion interactions at incident momentum of 4.5 GeV/ c per nucleon. A comparative study is made (whenever possible) with p-emulsion interaction data at the same incident momentum per nucleon. The linear dependences of different multplicities on shower and compound multiplicity, e.g., 〈 n i 〉 = a ij + k ij n j -( i ≠ j ), are also shown in this paper.

Study of multiparticle production in the interaction of 12C with photoemulsion nuclei at 4.5 GeV/c per nucleon

Abstract The paper presents exhaustive data on the interaction of 12 C-emulsion at 4.5 GeV/ c per nucleon. It deals with the multiplicity characteristics, i.e. multiplicity distribution, multiplicity correlation, mean multiplicity for the secondary particles, shower and compound (grey + shower) multiplicity scaling. We also discuss in this paper two-particle pseudorapidity correlations including a Monte Carlo simulation for comparison and the azimuthal angle dependence on it. A comparative study with the proton-emulsion interaction data at the same initial momentum, wherever possible, is also done.

On tanpura drone and brain electrical correlates

We describe a new conceptual framework of using tanpura drone for auditory stimulation in EEG. The question of reference for baseline EEG in the resting condition where the subject has no task to perform is addressed. In a laboratory setting we observed spontaneous brain electrical activity during Tanpura drone stimulation and periods of silence. The sound stimulus was given by an electronic substitute Tanpura (EST) that allows to closely control its parameters. The timbral characteristics of the drone samples are given. The brain-electrical response of the subject is analyzed with global descriptors, a way to monitor the course of activation in the time domain in a three-dimensional state space, revealing patterns of global dynamical states of the brain. Preliminary results are presented that serve as a stepping stone for a larger longitudinal study.

Observation of hot and cold events in the 12C-emulsion interaction at 4.5 GeV/c per nucleon-a signal for quark matter formation?

The authors present a study of the transverse momentum distribution of relativistic alpha particles emerging from the interaction of 12C and emulsion at 4.5 GeV/c per nucleon. A large statistics study of 1200 events when compared with the Maxwell-Boltzmann distribution reveals the existence of two temperatures, a hot and a cold, since a single Maxwell-Boltzmann distribution cannot fit the peak and the tail simultaneously. This yield of two distinctly different temperatures in the fragmentation region may be interpreted as a possible signal for the formation of a quark-gluon plasma.

Detrended Fluctuation and Power Spectral Analysis of alpha and delta EEG brain rhythms to study music elicited emotion

The study reports the effect of two different types of Hindustani music which are supposed to evoke contrasting emotions on brain activity using Electroencephalography (EEG) data. Two different sets of Hindustani music raga clips of contrasting emotion (romantic/sorrow) were used in the study. EEG was performed on five male subjects while they listened to the clips. The linear analysis of their alpha and delta spectral power showed that in most cases arousal based activities were enhanced in both the subjects while they listened to the two music clips. Further, we used a robust nonlinear method called Detrended Fluctuation Analysis (DFA) to analyze the scaling behavior of the observed fluctuations in EEG. The scaling exponent (α) values determined for the different experimental conditions show different levels of neural activity when the two different types of music are played. The implications are discussed in detail.

Chaotic Brain, Musical Mind-A Non-Linear eurocognitive Physics Based Study

Music engages much of the brain, and coordinates a wide range of processing mechanisms. This naturally invites consideration of how music processing in the brain might relate to other complex dynamical abilities. The tremendous ability that music has to affect and manipulate emotions and the brain is undeniable, and yet largely inexplicable. The study of music cognition is drawing an increasing amount of research interest. Like language, music is a human universal involving perceptual discrete elements organized into hierarchically structured sequences. Music can thus provide the study of brain mechanisms, underlying complex sound processing, and also can provide novel insights into the functional and neural architecture of brain functions. The change in the structure and form of music might bring a change in the neural dynamics. So it is important to study and analyze music and see its correlation with the changes it brings about in the neural dynamics. This work is essentially a case report of the various robust scientific nonlinear tools used by us in the assessment of complex neural dynamics induced by a variety of musical clips. Also, the inherent self-similarity in the musical clips can also be studied with the help of these analysis techniques. These methods can be best described taking the example of a mathematical microscope which can wonderfully describe the complex nature of various bio-signals as well as the music signals. The findings and implications are discussed in detail.

Multifractal Detrended Fluctuation Analysis of the music induced EEG signals

The electrical activity of the human brain arising from the effect of listening to music has been recorded with the help of EEG recordings in different electrodes. The non-linear EEG signals arising from various lobes of the brain has been studied with the help of a robust technique called Multifractal Detrended Fluctuation Analysis (MFDFA). The presence of multifractality has been justified by the help of MATLAB software and the multifractal spectrum has been drawn for various signals. The spectral widths and the Hurst exponents are compared with a random set of data to verify the presence of self-similarity in the signals. The results are discussed in detail.

Emotion specification from musical stimuli: An EEG study with AFA and DFA

The present study reports interesting findings in regard to emotional arousal based activities while listening to two Hindustani classical ragas of contrast emotion. EEG data was taken on 5 naïve listeners while they listened to two ragas — Bahar and Mia ki Malhar which are conventionally known to portray contrast emotions. The EEG data were analyzed with the help of two robust non-linear tools viz. Adaptive Fractal Analysis (AFA) and Detrended Fluctuation Analysis (DFA). A comparative study of the Hurst Exponents obtained from the two methods have been shown which shows that DFA provides more rigorous results compared to AFA when it comes to the scaling analysis of bio-signal data. The results and implications have been discussed in detail.

Universality and Domain Specificity of Emotion-A Quantitative Non Linear EEG Based Approach

Music has been present in human culture since time immemorial, some say music came even before speech. The effort to understand the wide variety of emotions evoked by music has started not long back. With the advent and rapid growth of various neurological bio-sensors we can now attempt to quantify various dimensions of emotional experience induced by music especially instrumental music – since it is free from any language barriers. In this study, we took eight (8) cross cultural instrumental clips originating mainly from Indian and Western music. A listening test comprising of 100 participants across the globe was conducted to associate each clip with its corresponding emotional valence. The participants were asked to mark each clip according to their perception of four basic emotions (joy/sorrow and anxiety/serenity) invoked by each instrumental clip. EEG study was then conducted on 10 participants to measure the response evoked by the same instrumental clips in the alpha and theta frequency regions. We took the help of latest non-linear multi-fractal analysis technique – MFDFA to estimate the change in multi-fractal spectral width (corresponding to alpha as well as theta waves) associated with each of the clips in frontal, temporal and occipital lobes. The response in the alpha domain reveals a hint in the direction of universality of music, while in theta domain we have culture specific response. Moreover, we tried to develop alpha as well as theta multi-fractal spectral width as a single parameter with which we can quantify the valence and arousal based effects corresponding to a particular musical clip. The results and implications are discussed in detail.

Forward-backward multiplicity correlations of pions and protons for different temperature events in heavy-ion interactions

A comparison of transverse momentum (PT) distribution of the alpha particles emitted as projectile fragments from12C-emulsion interaction at 4.5 A GeV/c with double Maxwell-Boltzmann distribution yields two temperatures in the projectile fragmentation region, i.e., 10 MeV and 40 MeV with different reaction mechanisms, thereby giving rise to two classes of events. This work presents a detailed study of the multiplicity characteristics for pions and protons emitted in both forward and backward hemispheres in these two classes of events. The results show some interesting features in these two classes.