Effects of thermal conduction in sonoluminescence

We show by numerical hydrodynamic calculations that there are two important effects of thermal conduction in sonoluminescence: (i) the bubble remains close to being isothermal during the expansion phase; and (ii) a cold, dense layer of air is formed at the bubble wall during the contraction phase. These conclusions are not sensitive to the particular equation of state used, although details of the dynamical evolution of the bubble are

State detection using coherent Raman repumping and two-color Raman transfers

We demonstrate state detection based on coherent Raman repumping and a two-color Raman state transfer. The Raman coupling during detection selectively eliminates unwanted dark states in the fluorescence cycle without compromising the immunity of the desired dark state to off-resonant scattering. We demonstrate this technique using $^{137}\mathrm{Ba}^+$ where a combination of Raman coupling and optical pumping leaves the $D_{3/2}$ $\ket{F"=3,m_F"=3}$ metastable state optically dark and immune to off-resonant scattering. All other states are strongly coupled to the upper $P_{1/2}$ levels. We achieve a single shot state-detection efficiency of $89.6(3)$ in a $1\mathrm{ms}$ integration time, limited almost entirely by technical imperfections. Shelving to the $\ket{F"=3,m_F"=3}$ state before detection is performed via a two-color Raman transfer with a fidelity of $1.00(3)$

Muon spin rotation study of the topological superconductor SrxBi2Se3

We report transverse-field (TF) muon spin rotation experiments on single crystals of the topological superconductor Sr$_x$Bi$_2$Se$_3$ with nominal concentrations $x=0.15$ and $0.18$ ($T_c \sim 3$ K). The TF spectra ($B= 10$ mT), measured after cooling to below $T_c$ in field, did not show any additional damping of the muon precession signal due to the flux line lattice within the experimental uncertainty. This puts a lower bound on the magnetic penetration depth $\lambda \geq 2.3 ~\mu$m. However, when we induce disorder in the vortex lattice by changing the magnetic field below $T_c$ a sizeable damping rate is obtained for $T \rightarrow 0$. The data provide microscopic evidence for a superconducting volume fraction of $\sim 70~ \%$ in the $x=0.18$ crystal and thus bulk superconductivity.Comment: 6 pages, includes 4 figure

Turbulence and turbulent events in tidal bores: field observations

A tidal bore is a compressive wave of tidal origin, propagating upstream as the tidal flow turns to rising when a macro-tidal flood flow enters a funnel shaped river mouth with shallow waters. New field measurements were conducted in the Garonne River tidal bore at Arcins in 2015. Instantaneous velocity measurements were performed continuously at high-frequency prior to, during and after each bore. The bore occurrence had a marked effect on the velocity and turbulent Reynolds stress field, with large and rapid fluctuations, during the bore passage and the early flood tide. A turbulent event analysis was conducted in the highly unsteady rapidly-varied tidal bore flow. The method detects bursting events by comparing the absolute value of an instantaneous turbulent flux with its standard deviation. This analysis, based upon basic concepts, was extended to the rapidly varied, highly-unsteady tidal bore flood flow motion. The turbulent event data analysis showed relatively close results for all studies and all fluxes. A very large majority of turbulent events had a duration less than 0.01 s, with on average 20 turbulent events per second. During all studies, the event duration showed some tidal trend, with longer turbulent events immediately after the tidal bore passage, occurring simultaneously with sediment erosion processes

The impact of the Medicines Control Council backlog and fast-track review system on access to innovative and new generic and biosimilar medicines of public health importance in South Africa

The fast-track registration policy of the South African National Department of Health allows for rapid registration of new medicines of public health importance and of all medicines on the Essential Medicines List, most of which are generics. No limit is placed on the number of generic brands of a medicine that can be submitted for fast-track registration. This, together with resource constraints at the regulator, may delay access to important new medicines, new fixed-dose combinations of critical medicines or affordable versions of biological medicines (biosimilars). One reason for not limiting the number of fast-track generic applications was to promote price competition among generic brands. We found this not to be valid, since market share correlated poorly with price. Generic brands with high market share were, mostly, those that were registered first. We propose that the number of generic brands accepted for fast-tracking be limited to not more than seven per medicine.

Micro-evaporators for kinetic exploration of phase diagrams

We use pervaporation-based microfluidic devices to concentrate species in aqueous solutions with spatial and temporal control of the process. Using experiments and modelling, we quantitatively describe the advection-diffusion behavior of the concentration field of various solutions (electrolytes, colloids, etc) and demonstrate the potential of these devices as universal tools for the kinetic exploration of the phases and textures that form upon concentration

Magnetodielectric effect in nickel nanosheet-Na-4 mica composites

Nickel nanosheets of thickness 0.6 nm were grown within the nanochannels of Na-4 mica template. The specimens show magnetodielectric effect at room temperature with a change of dielectric constant as a function of magnetic field, the electric field frequency varying from 100 to 700 kHz. A decrease of 5% in the value of dielectric constant was observed up to a field of 1.2 Tesla. This is explained by an inhomogeneous two-component composite model as theoretically proposed recently. The present approach will open up synthesis of various nanocomposites for sensor applications.Comment: 11 pages, 7 figure