Journal of the Transvaal, Natal and Orange Free State Provincial Institutes of South African Architects and the Chapter of South African Quantity Surveyors

JournalsSouth African Architectural RecordInstitutes of South African Architects and the Chapter of South African Quantity Surveyor

Duration of Classicality of Homogeneous Condensates with Attractive Interactions

Dark matter axions and other highly degenerate bosonic fluids are commonly described by classical field equations. In a recent paper \cite{BECprop} we calculated the duration of classicality of homogeneous condensates with attractive contact interactions and of self-gravitating homogeneous condensates in critical expansion. According to their classical equations of motion, such condensates persist forever. In their quantum evolution parametric resonance causes quanta to jump in pairs out of the condensate into all modes with wavevector less than some critical value. We estimated in each case the time scale over which the condensate is depleted and after which a classical description is invalid.Comment: 5 pages, no figures, contributed to the 13th Patras Workshop on Axions, WIMPs and WISPs, Thessaloniki, May 15 to 19, 201

A Preliminar Evidence of Quantum Like Behavior in Measurements of Mental States

Experimental results presented in this paper supports the hypothesis on quantum-like statistical behaviour of cognitive systems (at least human beings). Our quantum-like approach gives the possibility to represent mental states by Hilbert space vectors (complex amplitudes). Such a representation induces huge reduction of information about a mental state. We realize an approach that has no direct relation with reductionist quantum models and we are not interested in statistical behavior of micro systems forming the macro system of the brain. We describe only probabilistic features of cognitive measurements. Our quantum-like approach describes statistics of measurements of cognitive systems with the aim to ascertain if cognitive systems behave as quantum-like systems where here quantum-like cognitive behavior means that cognitive systems result to be very sensitive to changes of the context with regard to the complex of the mental conditions

Axion dark matter echo: A detailed analysis

It was recently shown that a powerful beam of radio/microwave radiation sent out to space can produce detectable backscattering via the stimulated decay of ambient axion dark matter. This echo is a faint and narrow signal centered at an angular frequency close to half the axion mass. In this article, we provide a detailed analytical and numerical analysis of this signal, considering the effects of the axion velocity distribution as well as the outgoing beam shape. In agreement with the original proposal, we find that the divergence of the outgoing beam does not affect the echo signal, which is only constrained by the axion velocity distribution. Moreover, our findings are relevant for the optimization of the experimental parameters in order to attain maximal signal-to-noise ratio or minimal energy consumption