Unitary relation between a harmonic oscillator of time-dependent frequency and a simple harmonic oscillator with and without an inverse-square potential

The unitary operator which transforms a harmonic oscillator system of time-dependent frequency into that of a simple harmonic oscillator of different time-scale is found, with and without an inverse-square potential. It is shown that for both cases, this operator can be used in finding complete sets of wave functions of a generalized harmonic oscillator system from the well-known sets of the simple harmonic oscillator. Exact invariants of the time-dependent systems can also be obtained from the constant Hamiltonians of unit mass and frequency by making use of this unitary transformation. The geometric phases for the wave functions of a generalized harmonic oscillator with an inverse-square potential are given.Comment: Phys. Rev. A (Brief Report), in pres

Exact quantum states of a general time-dependent quadratic system from classical action

A generalization of driven harmonic oscillator with time-dependent mass and frequency, by adding total time-derivative terms to the Lagrangian, is considered. The generalization which gives a general quadratic Hamiltonian system does not change the classical equation of motion. Based on the observation by Feynman and Hibbs, the propagators (kernels) of the systems are calculated from the classical action, in terms of solutions of the classical equation of motion: two homogeneous and one particular solutions. The kernels are then used to find wave functions which satisfy the Schr\"{o}dinger equation. One of the wave functions is shown to be that of a Gaussian pure state. In every case considered, we prove that the kernel does not depend on the way of choosing the classical solutions, while the wave functions depend on the choice. The generalization which gives a rather complicated quadratic Hamiltonian is simply interpreted as acting an unitary transformation to the driven harmonic oscillator system in the Hamiltonian formulation.Comment: Submitted to Phys. Rev.

Exact Eigenfunctions of NN-Body system with Quadratic Pair Potential

We obtain all the exact eigenvalues and the corresponding eigenfunctions of $N$-body Bose and Fermi systems with Quadratic Pair Potentials in one dimension. The originally existed first excited state level is missing in one dimension, which results from the operation of symmetry or antisymmetry of identical particles. In two and higher dimensions, we give all the eigenvalues and the analytical ground state wave functions and the number of degeneracy. Through the comparison with Avinash Khare's results, we have perfected his results.Comment: 7 pages,1 figur

On the correlation between Nd:YAG laser-induced wettability characteristics modification and osteoblast cell bioactivity on a titanium alloy

The factors responsible for modifications to the wettability characteristics of a titanium (Ti6Al4V) alloy bio-metal following Nd:YAG laser treatment and the effects thereof on the response of osteoblast cells were considered in this work. It was found that interaction of the Nd:YAG laser beam with the Ti6Al4V alloy resulted in the wettability characteristics of the bio-metal improving. Such improvements in the wettability characteristics of the Ti6Al4V alloy were found to be due to: an increase in the surface roughness; and increase in the surface oxygen content and an increase in the polar component of the surface energy. From the cell response tests it was determined that the osteoblast cell adhesion and proliferation on the Nd:YAG laser treated Ti6Al4V alloy samples was considerably greater than on the untreated samples. By isolating the effects of surface roughness it was possible to confirm or refute the existence of a correlation between wettability characteristics and osteoblast cell bioactivity for the Nd:YAG laser treated Ti6Al4V alloy. The findings indicated that the aspects of wettability characteristics: surface oxygen content and polar component of the surface energy play an important role in promoting cell proliferation, particularly when surface roughness was simultaneously increased. Thus it was possible to conclude that the wettability characteristics of the Nd:YAG laser treated Ti6Al4V alloy were correlated to osteoblast cell bioactivity

A geometric approach to time evolution operators of Lie quantum systems

Lie systems in Quantum Mechanics are studied from a geometric point of view. In particular, we develop methods to obtain time evolution operators of time-dependent Schrodinger equations of Lie type and we show how these methods explain certain ad hoc methods used in previous papers in order to obtain exact solutions. Finally, several instances of time-dependent quadratic Hamiltonian are solved.Comment: Accepted for publication in the International Journal of Theoretical Physic

Quantum transport through STM-lifted single PTCDA molecules

Using a scanning tunneling microscope we have measured the quantum conductance through a PTCDA molecule for different configurations of the tip-molecule-surface junction. A peculiar conductance resonance arises at the Fermi level for certain tip to surface distances. We have relaxed the molecular junction coordinates and calculated transport by means of the Landauer/Keldysh approach. The zero bias transmission calculated for fixed tip positions in lateral dimensions but different tip substrate distances show a clear shift and sharpening of the molecular chemisorption level on increasing the STM-surface distance, in agreement with experiment.Comment: accepted for publication in Applied Physics

Precision Measurement of the Proton and Deuteron Spin Structure Functions g2 and Asymmetries A2

We have measured the spin structure functions g2p and g2d and the virtual photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 0.7 < Q^2 < 20 GeV^2 by scattering 29.1 and 32.3 GeV longitudinally polarized electrons from transversely polarized NH3 and 6LiD targets. Our measured g2 approximately follows the twist-2 Wandzura-Wilczek calculation. The twist-3 reduced matrix elements d2p and d2n are less than two standard deviations from zero. The data are inconsistent with the Burkhardt-Cottingham sum rule if there is no pathological behavior as x->0. The Efremov-Leader-Teryaev integral is consistent with zero within our measured kinematic range. The absolute value of A2 is significantly smaller than the sqrt[R(1+A1)/2] limit.Comment: 12 pages, 4 figures, 2 table

Measurement of the Proton and Deuteron Spin Structure Functions g2 and Asymmetry A2

We have measured the spin structure functions g2p and g2d and the virtual photon asymmetries A2p and A2d over the kinematic range 0.02 < x < 0.8 and 1.0 < Q^2 < 30(GeV/c)^2 by scattering 38.8 GeV longitudinally polarized electrons from transversely polarized NH3 and 6LiD targets.The absolute value of A2 is significantly smaller than the sqrt{R} positivity limit over the measured range, while g2 is consistent with the twist-2 Wandzura-Wilczek calculation. We obtain results for the twist-3 reduced matrix elements d2p, d2d and d2n. The Burkhardt-Cottingham sum rule integral - int(g2(x)dx) is reported for the range 0.02 < x < 0.8.Comment: 12 pages, 4 figures, 1 tabl

Tracking echovirus eleven outbreaks in Guangdong, China

In April 2019, a suspect cluster of enterovirus cases was reported in a neonatology department in Guangdong, China, resulting in five deaths. We aimed to investigate the pathogen profiles in fatal cases, the circulation and transmission pattern of the viruses by combining metatranscriptomic, phylogenetic, and epidemiological analyses. Metatranscriptomic sequencing was used to characterize the enteroviruses. Clinical and environmental surveillance in the local population was performed to understand the prevalence and genetic diversity of the viruses in the local population. The possible source(s), evolution, transmission, and recombination of the viruses were investigated by incorporating genomes from the current outbreak, from local retrospective surveillance, and from public databases. Metatranscriptomic analysis identified Echovirus 11 (E11) in three fatal cases. Seroprevalence of neutralization antibody to E11 was 35 to 44 per cent in 3–15 age groups of general population, and the viruses were associated with various clinical symptoms. From the viral phylogeny, nosocomial transmissions were identified and all E11 2019 outbreak strains were closely related with E11 strains circulating in local population 2017–19. Frequent recombination occurred among the 2019 Guangdong E11 outbreak strains and various genotypes in enterovirus B species. This study provides an example of combining advanced genetic technology and epidemiological surveillance in pathogen diagnosis, source(s), and transmission tracing during an infectious disease outbreak. The result highlights the hidden E11 circulation and the risk of viral transmission and infection in the young age population in China. Frequent recombination between Guangdong-like strains and other enterovirus genotypes also implies the prevalence of these emerging E11 strains

pi Conjugated small molecules enable efficient perovskite growth and charge extraction for high performance photovoltaic devices

A amp; 960; conjugated small molecule N,N amp; 8242; bis naphthalen 1 yl N,N bis phenyl benzidine NPB is introduced into a poly bis 4 phenyl 2,4,6 trimethylphenyl amine PTAA hole transport layer in inverted perovskite solar cells PSCs . The NPB doping induces better perovskite crystal growth owing to a strong amp; 960; amp; 960; interaction with PTAA and cation amp; 960; interactions with CH3NH3 MA . In addition, NPB doping not only improves the wettability of PTAA and regulates the perovskite crystallization to achieve a larger grain size, but also moves the valence band energy of the hole transport layer closer to the perovskite layer. Consequently, the fabricated PSCs delivered a power conversion efficiency PCE of 20.15 , with a short circuit current density JSC of 22.60 amp; 8239;mA cm2 and open circuit voltage VOC of 1.14 amp; 8239;V. This outcome indicates that PTAA NPB composite materials present great potential for fabricating high performance PSC