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In this work, momentum-space decoherence using minimum and nonminimum-uncertainty-product (stretched) Gaussian wave packets in the framework of Caldeira-Leggett formalism and under the presence of a linear potential is studied. As a dimensionless measure of decoherence, purity, a quantity appearing in the definition of the linear entropy, is studied taking into account the role of the stretching parameter. Special emphasis is on the open dynamics of the well-known cat states and bosons and fermions compared to distinguishable particles. For the cat state, while the stretching parameter speeds up the decoherence, the external linear potential strength does not affect the decoherence time; only the interference pattern is shifted. Furthermore, the interference pattern is not observed for minimum-uncertainty-product-Gaussian wave packets in the momentum space. Concerning bosons and fermions, the question we have addressed is how the symmetry of the wave functions of indistinguishable particles is manifested in the decoherence process, which is understood here as the loss of being indistinguishable due to the gradual emergence of classical statistics with time. We have observed that the initial bunching and anti-bunching character of bosons and fermions, respectively, in the momentum space are not preserved as a function of the environmental parameters, temperature, and damping constant. However, fermionic distributions are slightly broader than the distinguishable ones and these similar to the bosonic distributions. This general behavior could be interpreted as a residual reminder of the symmetry of the wave functions in the momentum space for this open dynamics.
RESUMEN
OBJECTIVE: To develop a competency based discriminatory assessment method for physiology practical examination. METHOD: Results from 1st professional M.B.B.S. Part I and II of three batches were taken and students performance in traditional and objective structured practical examination (OSPE) were compared. The course objective for practical examination of all three batches were same. However, Batch II appeared in the conventional examination, while Batches III and IV were examined by OSPE. RESULTS: The mean score of Batch II was 68 +/- 6, of Batch III 53 +/- 13 and Batch IV 50 +/- 16. Batch II had thus an overall higher score as compared to Batches III and IV. The comparison of mean scores using ANOVA showed a significant (P < .001) difference between scores of Batch II as compared to Batches III and IV. Tukey's pair wise comparison of the batches showed a significant difference between batches II and III (95% CI for difference: 9.1, 20.5 with P < 0.001) and batches II and IV (95% CI for difference: 12.2, 23.6 with P < 0.001). However, no significant difference was found between batches III and IV (95% CI for difference: -2.6, 8.8 with P = 0.27). The result also showed that Batch II with conventional method of examination had a lesser spread around the mean (scores ranging from 52 to 81) as compared to Batch III (25 to 80) and Batch IV (14 to 90). CONCLUSION: OSPE is an effective tool to discriminate between good and poor performers in physiology practical examinations.