Steering between Bloch oscillation and dipole oscillation in parabolic optical waveguide arrays

We study the optical oscillations of supermodes in planar optical waveguide arrays with parabolically graded propagation constant in individual waveguide interacting through nearest neighbor couplings. In these arrays, we have identified a transition between a symmetric dipole oscillation (DO) and a symmetry-breaking Bloch oscillation (BO) under appropriate conditions. There exist obvious correspondences between gradon localization and various optical oscillations. By virtue of an analogue between the oscillation of optical system and that of a plane pendulum, we propose a shift of the graded profile to cause a transition from BO to DO. We confirm the optical transition by means of Hamiltonian optics, as well as by the field evolution of the supermodes. The results offer great potential applications in optical switching, which can be applied to design suitable optical devices.Comment: Submitted to JOSA B for publication

Recurrent Meningeal Hemangiopericytoma with Multiple Metastasis and Hypoglycemia: A Case Report

Aims. We report on the unusual case of a 43-year-old man who developed recurrent meningeal hemangiopericytoma and presented with hypoglycemia 6 years after excision of the tumor. Methods and Results. We utilized computed tomography to assure multiple tumor metastasis and cranial recurrence of previous meningeal hemangiopericytoma and clinical laboratory tests and immunohistochemical staining to characterize this case. Magnetic resonance imaging and computed tomography showed the recurrent tumor at original torcular site was increased in size. Abnormal low levels of growth hormone, insulin, and insulin-like growth factor-I except insulin-like growth factor-II were detected in the serum. By immunohistochemistry, the neoplastic cells characteristically express diffusely CD99, bcl2, and variable CD34. After radio- and chemotherapy, serum glucose level of the patient returned to normal. Conclusions. Comparing other brain tumors, meningeal hemangiopericytoma has a higher recurrent and metastatic rate, but this tumor with hypoglycemia is very rare

Harmonic oscillations and their switching in elliptical optical waveguide arrays

We have studied harmonic oscillations in an elliptical optical waveguide array in which the coupling between neighboring waveguides is varied in accord with a Kac matrix so that the propagation constant eigenvalues can take equally spaced values. As a result, long-living Bloch oscillation (BO) and dipole oscillation (DO) are obtained when a linear gradient in the propagation constant is applied. Moreover, we achieve a switching from DO to BO or vice versa by ramping up the gradient profile. The various optical oscillations as well as their switching are investigated by field evolution analysis and confirmed by Hamiltonian optics. The equally spaced eigenvalues in the propagation constant allow viable applications in transmitting images, switching and routing of optical signals.Comment: 14 pages, 5 figure

Pediatric osteomyelitis due to rare tropical multi-drug resistance (MDR) organisms: a treatment quandary

Osteomyelits due to concurrent multi-drug resistance organisms is difficult to treat for any surgeon and infectious disease physician. An eleven-year-old boy presenting with an open fracture of the left radius and ulna after a fall in a stagnant wet field. Despite prophylactic antibiotics and surgical intervention, the open wound was infected, and Chromobacterium violaceum as well as Klebsiella pneumoniae were isolated. He was treated with six weeks of parenteral cefepime and amikacin and was discharged upon clinical improvement. Unfortunately, chronic osteomyelitis set in with persistent sinus drainage. He then underwent a second procedure for debridement of the wound and Burkholderia pseudomallei was isolated. Parenteral antibiotic therapy was initiated progressing with a marked improvement. However, the long course of antibiotics had exhausted the patient and his family, leading to a premature interruption of the parenteral antibiotic. Despite the suboptimal antibiotic course, there were no signs of relapsed osteomyelitis during subsequent review. The timely surgical intervention with appropriate sampling for subsequent microorganism isolation guided the suitability of the treatment line

Stripe order in the underdoped region of the two-dimensional Hubbard model

Competing inhomogeneous orders are a central feature of correlated electron materials including the high-temperature superconductors. The two- dimensional Hubbard model serves as the canonical microscopic physical model for such systems. Multiple orders have been proposed in the underdoped part of the phase diagram, which corresponds to a regime of maximum numerical difficulty. By combining the latest numerical methods in exhaustive simulations, we uncover the ordering in the underdoped ground state. We find a stripe order that has a highly compressible wavelength on an energy scale of a few Kelvin, with wavelength fluctuations coupled to pairing order. The favored filled stripe order is different from that seen in real materials. Our results demonstrate the power of modern numerical methods to solve microscopic models even in challenging settings

Associations between child maltreatment and adolescents’ health-related quality of life and emotional and social problems in low-income families, and the moderating role of social support

This study aimed to examine the associations between different types of child maltreatment and health-related quality of life (HRQoL) and emotional and social problems in adolescents, and to examine the moderating effect of social support on those associations. A cross-sectional survey was conducted between January and June 2016 in Hong Kong. The sample comprised 351 parent and adolescent dyads from low-income families. The parents reported on child maltreatment (physical abuse, psychological aggression, and neglect), and the adolescents reported on their HRQoL, emotional problems, and social problems. The adolescents’ perceived social support was included as a potential moderator. Results of the study show that child physical abuse was strongly associated with emotional and social problems (B = 0.91-1.45, p < .05). Lower overall HRQoL was associated with psychological aggression (B = −3.96, p < .05) and neglect (B = −4.14, p < .05). Physical functioning was affected by psychological aggression (B = −3.16, p < .05), and emotional functioning was affected by neglect (B = −4.82, p < .05). Social functioning was impacted by all three types of maltreatment (B = −9.16 to −5.26, p < .05). This study extends previous literature by showing the varying effects of different types of child maltreatment on children’s health in the context of low-income families. The findings of this study also support that peer social support may buffer the effects of child physical abuse on adolescents’ emotional and social problems

Associations between child maltreatment and adolescents’ health-related quality of life and emotional and social problems in low-income families, and the moderating role of social support

This study aimed to examine the associations between different types of child maltreatment and health-related quality of life (HRQoL) and emotional and social problems in adolescents, and to examine the moderating effect of social support on those associations. A cross-sectional survey was conducted between January and June 2016 in Hong Kong. The sample comprised 351 parent and adolescent dyads from low-income families. The parents reported on child maltreatment (physical abuse, psychological aggression, and neglect), and the adolescents reported on their HRQoL, emotional problems, and social problems. The adolescents’ perceived social support was included as a potential moderator. Results of the study show that child physical abuse was strongly associated with emotional and social problems (B = 0.91-1.45, p < .05). Lower overall HRQoL was associated with psychological aggression (B = −3.96, p < .05) and neglect (B = −4.14, p < .05). Physical functioning was affected by psychological aggression (B = −3.16, p < .05), and emotional functioning was affected by neglect (B = −4.82, p < .05). Social functioning was impacted by all three types of maltreatment (B = −9.16 to −5.26, p < .05). This study extends previous literature by showing the varying effects of different types of child maltreatment on children’s health in the context of low-income families. The findings of this study also support that peer social support may buffer the effects of child physical abuse on adolescents’ emotional and social problems

The development of a virtual cycling simulator

Cycling is one of the current thirteen elite sports in Hong Kong. Despite cycling is one of the well known activities in the world and has numerous advantages for health, it is still far from popular in Hong Kong. In this research, a virtual cycling simulator is developed for exercise and entertainment purpose, and for promoting the cycling activity. The hardware of the cycling simulator consists of four major units including a bike platform, an actuation unit, a sensing unit and a display unit. The control system receives signals from the sensing unit and controls the motions of the actuation unit. It also computes and renders the virtual environment in real-time thereby providing the experience of cycling on different terrain models

Photonic Bloch-dipole-Zener Oscillations in Binary Parabolic Optical Waveguide Arrays

We have studied the propagation and Zener tunneling of light in the binary parabolic optical waveguide array (BPOWA), which consists of two evanescently coupled dissimilar optical waveguides. Due to Bragg reflections, BPOWA attains two minibands separated by a minigap at the zone boundary. Various coherent superpositions of optical oscillations and Zener tunneling occur for different parameters on the phase diagram. In particular, Bloch-Zener oscillation and a different type of Bloch-dipole-Zener oscillation are obtained by the field-evolution analysis. The results may have potential applications in optical splitting and waveguiding devices and shed light on the coherent phenomena in optical lattices.Comment: Submitted to JOSA