Binding energies of hydrogen-like impurities in a semiconductor in intense terahertz laser fields

A detailed theoretical study is presented for the influence of linearly polarised intense terahertz (THz) laser radiation on energy states of hydrogen-like impurities in semiconductors. The dependence of the binding energy for 1s and 2p states on intensity and frequency of the THz radiation has been examined.Comment: 14 pages, 4 figure

Truth-telling to the patient, family, and the sexual partner: a rights approach to the role of healthcare providers in adult HIV disclosure in China.

Patients' rights are central in today's legislation and social policies related to health care, including HIV care, in not only Western countries but around the world. However, given obvious socio-cultural differences it is often asked how or to what extent patients' rights should be respected in non-Western societies such as China. In this paper, it is argued that the patients' rights framework is compatible with Chinese culture, and that from the perspective of contemporary patient rights healthcare providers have a duty to disclose truthfully the diagnosis and prognosis to their patients, that the Chinese cultural practice of involving families in care should - with consent from the patient - be promoted out of respect for patients' rights and well-being, and that healthcare providers should be prepared to address the issue of disclosing a patient's HIV status to sexual partner(s). Legally, the provider should be permitted to disclose without consent from the patient but not obliged to in all cases. The decision to do this should be taken with trained sensitivity to a range of ethically relevant considerations. Post-disclosure counseling or psychological support should be in place to address the concerns of potentially adverse consequences of provider-initiated disclosure and to maximize the psychosocial and medical benefits of the disclosure. There is an urgent need for healthcare providers to receive training in ethics and disclosure skills. This paper concludes also with some suggestions for improving the centerpiece Chinese legislation, State Council's "Regulations on AIDS Prevention and Control" (2006), to further safeguard the rights and well-being of HIV patients

Optical spectroscopy study of Nd(O,F)BiS2 single crystals

We present an optical spectroscopy study on F-substituted NdOBiS$_2$ superconducting single crystals grown using KCl/LiCl flux method. The measurement reveals a simple metallic response with a relatively low screened plasma edge near 5000 \cm. The plasma frequency is estimated to be 2.1 eV, which is much smaller than the value expected from the first-principles calculations for an electron doping level of x=0.5, but very close to the value based on a doping level of 7$\%$ of itinerant electrons per Bi site as determined by ARPES experiment. The energy scales of the interband transitions are also well reproduced by the first-principles calculations. The results suggest an absence of correlation effect in the compound, which essentially rules out the exotic pairing mechanism for superconductivity or scenario based on the strong electronic correlation effect. The study also reveals that the system is far from a CDW instability as being widely discussed for a doping level of x=0.5.Comment: 5 pages, 5 figure

Edge Shear Flows and Particle Transport near the Density Limit in the HL-2A Tokamak

Edge shear flow and its effect on regulating turbulent transport have long been suspected to play an important role in plasmas operating near the Greenwald density limit $n_G$. In this study, equilibrium profiles as well as the turbulent particle flux and Reynolds stress across the separatrix in the HL-2A tokamak are examined as $n_G$ is approached in ohmic L-mode discharges. As the normalized line-averaged density $\bar{n}_e/n_G$ is raised, the shearing rate of the mean poloidal flow $\omega_{\rm sh}$ drops, and the turbulent drive for the low-frequency zonal flow (the Reynolds power $\mathcal{P}_{Re}$) collapses. Correspondingly, the turbulent particle transport increases drastically with increasing collision rates. The geodesic acoustic modes (GAMs) gain more energy from the ambient turbulence at higher densities, but have smaller shearing rate than low-frequency zonal flows. The increased density also introduces decreased adiabaticity which not only enhances the particle transport but is also related to a reduction in the eddy-tilting and the Reynolds power. Both effects may lead to the cooling of edge plasmas and therefore the onset of MHD instabilities that limit the plasma density

Simultaneous trapping and imaging of microbubbles at clinically relevant flow rates

Mechanisms for non-invasive target drug delivery using microbubbles and ultrasound have attracted growing interest. Microbubbles can be loaded with a therapeutic payload and tracked via ultrasound imaging to selectively release their payload at ultrasound-targeted locations. In this study, an ultrasonic trapping method is proposed for simultaneously imaging and controlling the location of microbubbles in flow by using acoustic radiation force. Targeted drug delivery methods are expected to benefit from the use of the ultrasonic trap, since trapping will increase the MB concentration at a desired location in human body. The ultrasonic trap was generated by using an ultrasound research system UARP II and a linear array transducer. The trap was designed asymmetrically to produces a weaker radiation force at the inlet of the trap to further facilitate microbubble entrance. A pulse sequence was generated that can switch between a long duration trapping waveform and short duration imaging waveform. High frame rate plane wave imaging was chosen for monitoring trapped microbubbles at 1 kHz. The working principle of the ultrasonic trap was explained and demonstrated in an ultrasound phantom by injecting SonoVue microbubbles flowing at 80 mL/min flow rate in a 3.5 mm diameter vessel