Criticality of the Mean-Field Spin-Boson Model: Boson State Truncation and Its Scaling Analysis

The spin-boson model has nontrivial quantum phase transitions at zero temperature induced by the spin-boson coupling. The bosonic numerical renormalization group (BNRG) study of the critical exponents $\beta$ and $\delta$ of this model is hampered by the effects of boson Hilbert space truncation. Here we analyze the mean-field spin boson model to figure out the scaling behavior of magnetization under the cutoff of boson states $N_{b}$. We find that the truncation is a strong relevant operator with respect to the Gaussian fixed point in $0<s<1/2$ and incurs the deviation of the exponents from the classical values. The magnetization at zero bias near the critical point is described by a generalized homogeneous function (GHF) of two variables $\tau=\alpha-\alpha_{c}$ and $x=1/N_{b}$. The universal function has a double-power form and the powers are obtained analytically as well as numerically. Similarly, $m(\alpha=\alpha_{c})$ is found to be a GHF of $\epsilon$ and $x$. In the regime $s>1/2$, the truncation produces no effect. Implications of these findings to the BNRG study are discussed.Comment: 9 pages, 7 figure

Transferrin-targeted porous silicon nanoparticles reduce glioblastoma cell migration across tight extracellular space

Mortality of glioblastoma multiforme (GBM) has not improved over the last two decades despite medical breakthroughs in the treatment of other types of cancers. Nanoparticles hold tremendous promise to overcome the pharmacokinetic challenges and off-target adverse effects. However, an inhibitory effect of nanoparticles by themselves on metastasis has not been explored. In this study, we developed transferrin-conjugated porous silicon nanoparticles (Tf@pSiNP) and studied their effect on inhibiting GBM migration by means of a microfluidic-based migration chip. This platform, designed to mimic the tight extracellular migration tracts in brain parenchyma, allowed high-content time-resolved imaging of cell migration. Tf@pSiNP were colloidally stable, biocompatible, and their uptake into GBM cells was enhanced by receptor-mediated internalisation. The migration of Tf@pSiNP-exposed cells across the confined microchannels was suppressed, but unconfined migration was unaffected. The pSiNP-induced destabilisation of focal adhesions at the leading front may partially explain the migration inhibition. More corroborating evidence suggests that pSiNP uptake reduced the plasticity of GBM cells in reducing cell volume, an effect that proved crucial in facilitating migration across the tight confined tracts. We believe that the inhibitory effect of Tf@pSiNP on cell migration, together with the drug-delivery capability of pSiNP, could potentially offer a disruptive strategy to treat GBM.</p

Awareness of lifestyle-related cancer risk factors and health promoting behaviours among nurses in Malaysia

Aims and objectives: To assess the awareness of lifestyle-related cancer risk factors and health-promoting behaviors among nurses in Malaysia. Background: The essence of nursing is caring. Nurses are known for taking care of others at the cost of their own health. Lack of self-care among nurses can lead to compassion fatigue, errors on the job, personal health problems and general disdain for life. The nurses' self-care starts with the awareness of modifiable health risk factors and their behaviors in promoting health. Design: A descriptive cross-sectional design. Methods: A total of 357 participants completed the questionnaire in a tertiary referral hospital. The awareness of cancer risk factors was measured based on twenty-nine established lifestyle factors. The health-promoting behaviors were evaluated by the Health-Promoting Lifestyle Profile II. Results: Almost half of the participants are overweight and obese. Awareness among the six clearly established lifestyle-related cancer risk factors showed alcohol gamering the highest number of participants, followed by cured meats, overweight, high red meat diets, low vegetables, and fruit diets, and insufficient physical activity. 37.7% and 47.4% of the participants reported low and moderate levels of health-promoting behavior respectively. The highest mean score reported in the spiritual growth subscale and the lowest in the physical activity subscale. Conclusion: Lifestyle-related cancer risk factors such as overweight, high red meat diets, low vegetables/fruit diets, and insufficient physical activity were not prioritized by the nurses. Although almost half of the nurses reported moderate levels of health-promoting behavior, it is worth noting that the nurses reported of the physical activity subscale to be the least. Relevance to clinical practice: The findings have provided a useful insight into the current health behaviors of nurses and may serve well as an important indicator as to where education and supportive services should target their focus

Evaluation of the photovoltaic potential in built environment using spatial data captured by unmanned aerial vehicles

10.1002/ese3.408Energy Science and Engineering752011-202

Fabrication and modulation characteristics of 1.3 µm p-doped InAs quantum dot vertical cavity surface emitting lasers

We present the fabrication of 1.3 µm waveband p-doped InAs quantum dot (QD) vertical cavity surface emitting lasers (VCSELs) with an extremely simple process. The continuous-wave saturated output power of 1.1 mW with a lasing wavelength of 1280 nm is obtained at room temperature. The high-speed modulation characteristics of p-doped QD VCSELs of two different oxide aperture sizes are investigated and compared. The maximum 3 dB modulation bandwidth of 2.5 GHz can be achieved at a bias current of 7 mA for a p-doped QD VCSEL with an oxide aperture size of 10 µm in the small signal frequency response measurements. The crucial factors for the 3 dB bandwidth limitation are discussed according to the parameters' extraction from frequency response

1.3-μm InAs quantum dot vertical cavity surface emitting lasers with planar electrode configuration

We present the 1.3-μm InAs quantum dot (QD) vertical cavity surface emitting lasers (VCSELs) with novel planar electrodes configuration. The lasing wavelength is around 1274 nm. The lowest threshold current of wafer level device is ~1 mA, which corresponds to a low threshold current density of ~1.3 kA/cm2 or 76 A/cm2 per QD layer. The maximum output power of 1 mW can be obtained at room temperature. High temperature stability can be seen in temperature dependence L-I characteristics of InAs QD VCSEL 3-dB modulation frequency response of 1.7 GHz can be obtained in the small signal response measurements