Spectral fluctuations and 1/f noise in the order-chaos transition regime

Level fluctuations in quantum system have been used to characterize quantum chaos using random matrix models. Recently time series methods were used to relate level fluctuations to the classical dynamics in the regular and chaotic limit. In this we show that the spectrum of the system undergoing order to chaos transition displays a characteristic $f^{-\gamma}$ noise and $\gamma$ is correlated with the classical chaos in the system. We demonstrate this using a smooth potential and a time-dependent system modeled by Gaussian and circular ensembles respectively of random matrix theory. We show the effect of short periodic orbits on these fluctuation measures.Comment: 4 pages, 5 figures. Modified version. To appear in Phys. Rev. Let

Antipathogenic Activity of Spirulina Powder

Spirulina is a microscopic blue-green alga in the shape of a spiral coil, living both in sea and fresh water. In this study, dried Spirulina was extracted at different solvents such as Hexane, Ethyl acetate, Ethanol, Butanol, Acetone, Methanol and chloroform. That extracts were stored in an airtight glass bottles in a refrigerator. Antimicrobial activity analysis from different pathogens and using well diffusion methods. Butanol extract of Spirulina also gave the highest antimicrobial activity of 19 mm against Staphylococcus epidermids, 18mm against Staphylococcus aureus and Aeromonas liquefaciens, 13mm against Candida glabrata, 12mm against Enterococcus feacalis, 11mm against Campylobacter coil and Vibrio cholerae and low activity against 5mm Salmonella typhi. Remaining solvents extracts antimicrobial activity low compare to butanol

Classical bifurcations and entanglement in smooth Hamiltonian system

We study entanglement in two coupled quartic oscillators. It is shown that the entanglement, as measured by the von Neumann entropy, increases with the classical chaos parameter for generic chaotic eigenstates. We consider certain isolated periodic orbits whose bifurcation sequence affects a class of quantum eigenstates, called the channel localized states. For these states, the entanglement is a local minima in the vicinity of a pitchfork bifurcation but is a local maxima near a anti-pitchfork bifurcation. We place these results in the context of the close connections that may exist between entanglement measures and conventional measures of localization that have been much studied in quantum chaos and elsewhere. We also point to an interesting near-degeneracy that arises in the spectrum of reduced density matrices of certain states as an interplay of localization and symmetry.Comment: 7 pages, 6 figure

Case studies to enhance online student evaluation: Bond University – Surveying students online to improve learning and teaching

One of the most sensible ways of improving learning and teaching is to ask the students for feedback. At the end of each teaching period (i.e. semester or term) all universities and many schools survey their students. Usually these surveys are managed online. Questions ask for student perceptions about teaching, assessment and workload. The survey administrators report four common problems

Chaos and Dynamical localization in interacting kicked systems

Is quantum localization preserved under the effect of interactions that make a system non-integrable and completely chaotic? This work attempts to answer this question through a detailed study of the momentum-coupled, two-body linear kicked rotor model. It was recently shown that dynamical many-body localization exists in an integrable model of spatially interacting linear kicked rotors. Later, such localized phases in a non-integrable model -- coupled relativistic kicked rotors -- were also shown to exist. However, the presence of dynamical localization remains an open question in an interacting system that is far from the integrable limit and hence is completely chaotic. In this work, we show that chaos can be induced in the integrable linear kicked rotor model through interactions between the momenta of rotors. An approximate estimate of its Lyapunov exponent is obtained. Further, the quantum dynamics of this chaotic model, upon variation of kicking and interaction strengths, is shown to exhibit a variety of phases -- classically induced localization, dynamical localization, subdiffusive and diffusive phases. We also discuss this perspective from entanglement production in this system. By defining an effective Hilbert space dimension, the entanglement growth rate can be understood using appropriate random matrix averages.Comment: 11 pages, 6 figure

THE POTENTIAL OF CANARIUM ODONTOPHYLLUM MIQ. (DABAI) AS ANTI-METHICILLIN RESISTANT STAPHYLOCOCCUS AUREUS AGENT

Objective: The present study evaluates the antimicrobial potential of C. Odontophyllum leaves against Methicillin-resistant Staphylococcus aureus, Candida albicans, Candida glabrata, Candida krusei, Candida tropicalis,  Aspergillus fumigatus, Aspergillus niger and Aspergillus flavus. Materials: The extracts from C. odontophyllum leaf were prepared using acetone, methanol and distilled waterprior to screening at concentrations from12.5 mg/ml to 100 mg/ml against the test microorganisms using disc diffusion method. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of the extracts against susceptible organisms were determined using microbroth dilution method and streak-plate technique, respectively. Results: Water produced the highest yield of extract (5.03%) followed by methanol (2.65%) and acetone (1.79%). Out of all the microbes tested, only MRSA was found to be susceptible towards acetone and methanol extracts of C. odontophyllum leaves which showed concentration-dependent growth inhibitory effect against MRSA. Despite the highest extractive potential of water, no antimicrobial activity was observed by the aqueous extract from the screening assay. The MIC values for methanol and acetone extracts were respectively,6.25 mg/ml and 3.125 mg/ml. The MBC value of methanol extract was twice its MIC value which was 12.5 mg/ml whereas the MIC and MBC values of acetone extract against MRSA were the same (3.125 mg/ml). Conclusion: C. odontophyllum leaves have the potential to be developed as an alternative phytotherapeutic agent against MRSA infection

Zero delay synchronization of chaos in coupled map lattices

We show that two coupled map lattices that are mutually coupled to one another with a delay can display zero delay synchronization if they are driven by a third coupled map lattice. We analytically estimate the parametric regimes that lead to synchronization and show that the presence of mutual delays enhances synchronization to some extent. The zero delay or isochronal synchronization is reasonably robust against mismatches in the internal parameters of the coupled map lattices and we analytically estimate the synchronization error bounds.Comment: 9 pages, 9 figures ; To appear in Phys. Rev.