A Bohr's Semiclassical Model of the Black Hole Thermodynamics

We propose a simple procedure for evaluating the main thermodynamical attributes of a Schwarzschild's black hole: Bekenstein-Hawking entropy, Hawking's temperature and Bekenstein's quantization of the surface area. We make use of the condition that the circumference of a great circle on the black hole horizon contains finite number of the corresponding reduced Compton's wavelength. It is essentially analogous to Bohr's quantization postulate in Bohr's atomic model interpreted by de Broglie's relation. We present black hole radiation in the form conceptually analogous to Bohr's postulate on the photon emission by discrete quantum jump of the electron within the Old quantum theory. It enables us, in accordance with Heisenberg's uncertainty relation and Bohr's correspondence principle, to make a rough estimate of the time interval for black hole evaporation, which turns out very close to time interval predicted by the standard Hawking's theory. Our calculations confirm Bekenstein's semiclassical result for the energy quantization, in variance with Frasca's (2005) calculations. Finally we speculate about the possible source-energy distribution within the black hole horizon.Comment: no figure

Joint theoretical and experimental study on elastic electron scattering from bismuth

We report on experimental elastic differential and integral cross sections for electron scattering from bismuth. The energy range of those measurements is 10-100 eV, while the scattered electron angular range in the differential cross section data is 10 degrees-150 degrees. We also supplement our experimental results with theoretical data from our optical potential approach, in this case applying two different sets of scattering potentials to the problem. Good overall qualitative accord is typically observed between our measured and calculated results, particularly when allowance is made for the dimer contribution in the experimental atomic beam

Testing foundations of quantum mechanics with photons

The foundational ideas of quantum mechanics continue to give rise to counterintuitive theories and physical effects that are in conflict with a classical description of Nature. Experiments with light at the single photon level have historically been at the forefront of tests of fundamental quantum theory and new developments in photonics engineering continue to enable new experiments. Here we review recent photonic experiments to test two foundational themes in quantum mechanics: wave-particle duality, central to recent complementarity and delayed-choice experiments; and Bell nonlocality where recent theoretical and technological advances have allowed all controversial loopholes to be separately addressed in different photonics experiments.Comment: 10 pages, 5 figures, published as a Nature Physics Insight review articl

Dynamic holdup in a countercurrent gas - flowing solids - packed bed contactors

Equations for the prediction of the holdup of dynamic solids in countercurrent gas flowing solids packed bed contactors are presented in this paper. The correlations do not require the use of parameters that need to be determined by experimental measurements in the actual system of interest. They could be used for a wide range of operational conditions, different packing types and a variety of flowing solids materials. The equations are compared with all available experimental data from the literature

Is kurjak antenatal neurodevelopmental test ready for routine clinical application? Bucharest consensus statement

Background: While two-dimensional ultrasound (2D US) is used only for the assessment of fetal startles and gene ral movements, introduction of Kurjak antenatal neuro developmental test (KANET) by four-dimensional ultrasound (4D US) enabled assessment of not only movements but also some signs used in postnatal neurological assessment like cranial sutures, head circumference and finger movements of the hand for the detection of neurological thumb (adducted thumb in the clenched feast). Overall impression on general movement called by Prechtl ‘Gestalt perception’ is also a part of KANET assessment. These parameters cannot be assessed by 2D US, and according to our opinion they are making the difference enabling more accurate and functionally more reliable assessment of the young and immature CNS. After Osaka standardization of KANET has been published, many studies on fetal behavior from different centers using this method have been conducted and published. Although there is lack of long-term follow-up of children who were assessed by KANET as fetuses, some conclusions on the usage of KANET test in clinical practice can be made. There are still inconclusive results of prenatal neurological assessment using KANET test in fetuses with borderline scores, although it was revealed that negative predictive value of the test as well as inter-observer reliability were satisfactory and acceptable. Conclusion: It can be concluded that KANET test can be used in everyday clinical practice for the follow-up of fetuses at neurological risk with the strong recommendation for strict and reliable multidisciplinary postnatal follow-up till the corrected age of at least 3 years and longer whenever appropriate. This will enable to make better correlation of prenatal KANET scores with postnatal neurodevelopmental outcomes. © 2015, Jaypee Brothers Medical Publishers (P) Ltd. All rights reserved