Neutron star cooling - a challenge to the nuclear mean field

The two recent density-dependent versions of the finite-range M3Y interaction (CDM3Y$n$ and M3Y-P$n$) have been probed against the bulk properties of asymmetric nuclear matter (NM) in the nonrelativistic Hartree Fock (HF) formalism. The same HF study has also been done with the famous Skyrme (SLy4) and Gogny (D1S and D1N) interactions which were well tested in the nuclear structure calculations. Our HF results are compared with those given by other many-body calculations like the Dirac-Brueckner Hartree-Fock approach or ab-initio variational calculation using free nucleon-nucleon interaction, and by both the nonrelativistic and relativistic mean-field studies using different model parameters. Although the two considered density-dependent versions of the M3Y interaction were proven to be quite realistic in the nuclear structure or reaction studies, they give two distinct behaviors of the NM symmetry energy at high densities, like the Asy-soft and Asy-stiff scenarios found earlier with other mean-field interactions. As a consequence, we obtain two different behaviors of the proton fraction in the $\beta$-equilibrium which in turn can imply two drastically different mechanisms for the neutron star cooling. While some preference of the Asy-stiff scenario was found based on predictions of the latest microscopic many-body calculations or empirical NM pressure and isospin diffusion data deduced from heavy-ion collisions, a consistent mean-field description of nuclear structure database is more often given by some Asy-soft type interaction like the Gogny or M3Y-P$n$ ones. Such a dilemma poses an interesting challenge to the modern mean-field approaches.Comment: Version accepted for publication in Phys. Rev.

Isospin dependence of 6He+p optical potential and the symmetry energy

A consistent folding analysis of the elastic p(6He,6He)p scattering and charge exchange p(6He,6Li*)n reaction data measured at Elab=41.6A MeV has been performed within the coupled channels formalism. We have used the isovector coupling to link the isospin dependence of 6He+p optical potential to the cross section of p(6He,6Li*)n reaction exciting the 0+ isobaric analog state (IAS) at 3.563 MeV in 6Li. Based on these results and the Hartree-Fock calculation of asymmetric nuclear matter using the same isospin-dependent effective nucleon-nucleon interaction, we were able to confirm that the most realistic value of the symmetry energy Esym is around 31 MeV. Our analysis has also shown that the measured charge exchange p(6He,6Li*)n data are quite sensitive to the halo tail of the 6He density used in the folding calculation and the IAS of 6Li is likely to have a halo structure similar to that established for the ground state of 6He.Comment: Accepted for publication in Phys. Rev.

Search-Based Planning and Replanning in Robotics and Autonomous Systems

In this chapter, we present one of the most crucial branches in motion planning: search-based planning and replanning algorithms. This research branch involves two key points: first, representing traverse environment information as discrete graph form, in particular, occupancy grid cost map at arbitrary resolution, and, second, path planning algorithms calculate paths on these graphs from start to goal by propagating cost associated with each vertex in graph. The chapter will guide researcher through the foundation of motion planning concept, the history of search-based path planning and then focus on the evolution of state-of-the-art incremental, heuristic, anytime algorithm families that are currently applied on practical robot rover. The comparison experiment between algorithm families is demonstrated in terms of performance and optimality. The future of search-based path planning and motion planning in general is also discussed

An Investigation of Thai High School Students' English Language Learning Problems

A way to improve English language teaching is an investigation of students' English language problems. This study therefore explored Thai high school students' English language learning problems. This was a case study, employing a survey design and using a questionnaire as instrument for data collection. The subjects were 104 high school students in Lampang Province, Thailand. The results of this study revealed the following findings. On listening, the students had difficulty in class discussion in English. On speaking, they had trouble with asking questions in English in the classroom. On reading, they could not understand English idioms. On writing, they were unable to finish essay writing within a limited time. On sociocultural perspectives on second language learning, they lacked opportunity to spend time associate with native speakers. On International communication barriers, on oral presentation for a lesson assignment, they rehearsed it only 2-3 times to prepare themselves. Lastly, of all language learning tasks, the most problematic English task was writing. This study is a puzzle to the whole picture. Future inquiry should replicate this study to see the whole picture of this issue

An Alternative Electrode System for Monitoring Belousov-Zhabotinsky Chemical Oscillations

The capability of copper-platinum (Cu/Pt) electrode system as a BelousovZhabotinsky (BZ) chemical oscillation monitor was compared with that of the normally used SCE/Pt electrode system, by testing it on three BZ systems, which were obtained by varying the oscillator in the combination bromate, oscillator and malonic acid. The oscillators, used separately, were cerium(IV), manganese(II) and ferroin [iron (II)-1,10- phenanthroline complex].Cu/Pt electrode gave essentially identical values of oscillation characteristics (oscillation period, peak potential, induction period, peak width) except peak potentials. This indicated that the Cu/Pt electrode system would be more useful than the SCE/Pt electrode system (which had chloride leakage problem), in electrical applications of chemical oscillations, such as electrical switches, which would depend only on the on/off frequency

Braking and Body Angles Control of an Insect-Computer Hybrid Robot by Electrical Stimulation of Beetle Flight Muscle in Free Flight

While engineers put lots of effort, resources, and time in building insect scale micro aerial vehicles (MAVs) that fly like insects, insects themselves are the real masters of flight. What if we would use living insect as platform for MAV instead? Here, we reported a flight control via electrical stimulation of a flight muscle of an insect-computer hybrid robot, which is the interface of a mountable wireless backpack controller and a living beetle. The beetle uses indirect flight muscles to drive wing flapping and three major direct flight muscles (basalar, subalar and third axilliary (3Ax) muscles) to control the kinematics of the wings for flight maneuver. While turning control was already achieved by stimulating basalar and 3Ax muscles, electrical stimulation of subalar muscles resulted in braking and elevation control in flight. We also demonstrated around 20 degrees of contralateral yaw and roll by stimulating individual subalar muscle. Stimulating both subalar muscles lead to an increase of 20 degrees in pitch and decelerate the flight by 1.5 m/s2 as well as an induce an elevation of 2 m/s2.Comment: 9 pages, 7 figures, supplemental video: https://youtu.be/P9dxsSf14LY . Cyborg and Bionic Systems 202

Mechanical Attributes of Fractal Dragons

Fractals are ubiquitous natural emergences that have gained increased attention in engineering applications, thanks to recent technological advancements enabling the fabrication of structures spanning across many spatial scales. We show how the geometries of fractals can be exploited to determine their important mechanical properties, such as the first and second moments, which physically correspond to the center of mass and the moment of inertia, using a family of complex fractals known as the dragons

Phenomenology of the Equivalence Principle with Light Scalars

Light scalar particles with couplings of sub-gravitational strength, which can generically be called 'dilatons', can produce violations of the equivalence principle. However, in order to understand experimental sensitivities one must know the coupling of these scalars to atomic systems. We report here on a study of the required couplings. We give a general Lagrangian with five independent dilaton parameters and calculate the "dilaton charge" of atomic systems for each of these. Two combinations are particularly important. One is due to the variations in the nuclear binding energy, with a sensitivity scaling with the atomic number as $A^{-1/3}$. The other is due to electromagnetism. We compare limits on the dilaton parameters from existing experiments.Comment: 5 page