Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016

[This corrects the article DOI: 10.1186/s13054-016-1208-6.].

Charge state switching of deep levels for low-power optical modulation in silicon waveguides

We demonstrate a method for the efficient modulation of optical wavelengths around 1550 nm in silicon waveguides. The amplitude of a propagating signal is mediated via control of the charge state of indium centers, rather than using free-carriers alone as in the plasma-dispersion effect. A 1×1 switch formed of an integrated p-i-n junction in an indium-doped silicon on insulator (SOI) waveguide provides 'normally-off' silicon absorption of greater than 7 dB at zero bias. This loss is decreased to 2.8 dB with application of a 6 V applied reverse bias, with a power consumption of less than 1 μW.

Optical modulation in silicon waveguides via charge state control of deep levels

The control of defect mediated optical absorption at a wavelength of 1550 nm via charge state manipulation is demonstrated using optical absorption measurements of indium doped Silicon-On-Insulator (SOI) rib waveguides. These measurements introduce the potential for modulation of waveguide transmission by using the local depletion and injection of free-carriers to change deep-level occupancy. The extinction ratio and modulating speed are simulated for a proposed device structure. A 'normally-off' depletion modulator is described with an extinction coefficient limited to 5 dB/cm and switching speeds in excess of 1 GHz. For a carrier injection modulator a fourfold enhancement in extinction ratio is provided relative to free carrier absorption alone. This significant improvement in performance is achieved with negligible increase in driving power but slightly degraded switching speed.

Excitatory and inhibitory responses of the ongoing sympathetic discharge in single renal neurons to liminal stimulation of aortic C-fibres in the rabbit

Excitatory and inhibitory responses of sympathetic discharge were recorded in single renal postganglionic neurons of rabbits anaesthetized with urethane and chloralose. The animals were vagotomized and had transected aortic nerves. Responses were elicited by single volleys in the aortic C-fibres. Excitatory responses consisted in short-lasting increase in the rate of ongoing sympathetic discharge and were followed by inhibitory responses. Excitatory effects together with inhibitory responses were seen in 68% of units (19/28). Only excitatory effects appeared in 2 neurons (7.1%) and only inhibitory effects in 7 neurons (25%). In renal neurons exhibiting both effects, the excitatory responses appeared after latency of 172 +/- 8 ms (x +/- S.D.) and had duration of 64 +/- 11 ms. Inhibitory effects had latency o f 257 +/- 10 ms and their duration amounted to 265 +/- 22 ms. In more than half of recordings the excitatory responses were separated from the inhibitory effects by discharge lasting 33 +/- 4 ms. Significant correlations between latencies of excitatory and inhibitory responses and between duration of excitatory and latency of inhibitory responses suggest interaction between both effects. Increase in the number of afferent volleys (1 through 5) evoked relatively small changes in duration of the excitatory effect indicating that temporal facilitation is of minor importance in generating this response. Temporal facilitation was found to play an important role in determining duration of the inhibitory response. Comparison of effects of unilateral and bilateral stimulation of the aortic C-fibres showed larger occlusion of durations of the excitatory than inhibitory responses.

ATP-regulated K+ channel in mitochondria: pharmacology and function

Mitochondria from several tissues contain a potassium-specific channel similar to the ATP-regulated K+ (K ATP) channel of the plasma membrane. The mitochondrial channel shares with the plasma membrane K ATP channel the sensitivity to sulfonylurea derivatives and some other blockers as well as to channel openers of diverse chemical character. In contrast to the plasma membrane channel, which is blocked by free ATP, the mitochondrial K ATP channel reconstituted into liposomes requires the ATP-Mg complex for inhibition. The mitochondrial K ATP channel, possibly in a concerted action with other K+ permeability pathways, plays an important role in mitochondrial volume control. Its function in the regulation of the components of the protonmotive force is also suggested.

Electron-density study of m-nitrophenol in the orthorhombic structure

m-Nitrophenol (m-NPH) occurs at room temperature in two solid modifications: monoclinic P21/n and orthorhombic P212121 [Pandarese, Ungaretti & Coda (1975). Acta Cryst. B31, 2671–2675]. The thermal vibrations and electronic-density distribution of the molecule in the orthorhombic structure have been analyzed in terms of Stewart's rigid pseudoatom model, using restricted Slater radial functions and angular multipole terms extending to actapoles for C, N and O and dipoles for H pseudoatoms. The net atomic charge and the in-crystal molecular dipole moment have been determined in order to understand the nature of the inter- and intramolecular charge transfer. The analysis suggests that aspherical pseudoatoms are essential for modeling the charge distribution in a noncentrosymmetric crystal. Careful consideration must also be given to the treatment of the H atoms, in the absence of complementary neutron diffraction data.