Random telegraph signal amplitudes in sub 100 nm (decanano) MOSFETs: a 3D `Atomistic' simulation study

In this paper we use 3D simulations to study the amplitudes of random telegraph signals (RTS) associated with the trapping of a single carrier in interface states in the channel of sub 100 nm (decanano) MOSFETs. Both simulations using continuous doping charge and random discrete dopants in the active region of the MOSFETs are presented. We have studied the dependence of the RTS amplitudes on the position of the trapped charge in the channel and on the device design parameters. We have observed a significant increase in the maximum RTS amplitude when discrete random dopants are employed in the simulations

Hierarchical approach to 'atomistic' 3-D MOSFET simulation

We present a hierarchical approach to the 'atomistic' simulation of aggressively scaled sub-0.1-μm MOSFETs. These devices are so small that their characteristics depend on the precise location of dopant atoms within them, not just on their average density. A full-scale three-dimensional drift-diffusion atomistic simulation approach is first described and used to verify more economical, but restricted, options. To reduce processor time and memory requirements at high drain voltage, we have developed a self-consistent option based on a solution of the current continuity equation restricted to a thin slab of the channel. This is coupled to the solution of the Poisson equation in the whole simulation domain in the Gummel iteration cycles. The accuracy of this approach is investigated in comparison to the full self-consistent solution. At low drain voltage, a single solution of the nonlinear Poisson equation is sufficient to extract the current with satisfactory accuracy. In this case, the current is calculated by solving the current continuity equation in a drift approximation only, also in a thin slab containing the MOSFET channel. The regions of applicability for the different components of this hierarchical approach are illustrated in example simulations covering the random dopant-induced threshold voltage fluctuations, threshold voltage lowering, threshold voltage asymmetry, and drain current fluctuations

Ring-opening copolymerization (ROCOP): synthesis and properties of polyesters and polycarbonates

Controlled routes to prepare polyesters and polycarbonates are of interest due to the widespread application of these materials and the opportunities provided to prepare new copolymers. Furthermore, ring-opening copolymerization may enable new poly(ester–carbonate) materials to be prepared which are inaccessible using alternative polymerizations. This review highlights recent advances in the ring-opening copolymerization catalysis, using epoxides coupled with anhydrides or CO2, to produce polyesters and polycarbonates. In particular, the structures and performances of various homogeneous catalysts are presented for the epoxide–anhydride copolymerization. The properties of the resultant polyesters and polycarbonates are presented and future opportunities highlighted for developments of both the materials and catalysts

Evaluation of the Intubating Laryngeal Mask Airway (ILMA) as an intubation conduit in patients with a cervical collar simulating fixed cervical spine

Background: Cervical spine immobilisation with a semi-rigid cervical collar imposes difficulty in tracheal intubation. There is increasing use of the Intubating Laryngeal Mask Airway (LMA- FastrachTM) for intubation in patients with difficult airways. The present study was conducted to assess its potential role for tracheal intubation in simulated fixed cervical spine patients.Method: After obtaining approval from the ethics committee and patients’ consent, this observational study was performed on 35 adult patients of either sex of ASA physical status I and II scheduled to undergo surgery under general anaesthesia requiring tracheal intubation. A two-piece semi-rigid cervical collar of appropriate size was positioned around the neck of patients. A standard anaesthesia protocol comprising glycopyrrolate, propofol and vecuronium was used for induction of anaesthesia. ILMA placement and blind tracheal intubation through this was attempted by using dedicated silicone tube provided with the ILMA set. Success rate, number of attempts required, time taken, difficulties encountered and any complication that occurred were noted. Anaesthesia was maintained with isoflurane in oxygen and nitrous oxide, pethidine and vecuronium. Following completion of surgery, neuromuscular blockade was reversed with glycopyrrolate and neostigmine.Results: The overall success rate was 85.7% and the success rate for ILMA placement at first attempt was 57.1%. Tracheal intubation was successful at first attempt in 70.5% of patients. The time taken for ILMA placement and tracheal intubation through this was 31.76 ± 9.74 and 34.04 ± 12.68 seconds respectively. Decreased mouth opening due to presence of the collar led to difficulty in ILMA placement.Conclusions: Blind tracheal intubation through ILMA is a possible option for airway management in patients with a semi-rigid cervical collar.Keywords: cervical collar, difficult airway, ILMA, intubatio

Constraints on the Growth and Spin of the Supermassive Black Hole in M32 From High Cadence Visible Light Observations

We present 1-second cadence observations of M32 (NGC221) with the CHIMERA instrument at the Hale 200-inch telescope of the Palomar Observatory. Using field stars as a baseline for relative photometry, we are able to construct a light curve of the nucleus in the g-prime and r-prime band with 1sigma=36 milli-mag photometric stability. We derive a temporal power spectrum for the nucleus and find no evidence for a time-variable signal above the noise as would be expected if the nuclear black hole were accreting gas. Thus, we are unable to constrain the spin of the black hole although future work will use this powerful instrument to target more actively accreting black holes. Given the black hole mass of (2.5+/-0.5)*10^6 Msun inferred from stellar kinematics, the absence of a contribution from a nuclear time-variable signal places an upper limit on the accretion rate which is 4.6*10^{-8} of the Eddington rate, a factor of two more stringent than past upper limits from HST. The low mass of the black hole despite the high stellar density suggests that the gas liberated by stellar interactions was primarily at early cosmic times when the low-mass black hole had a small Eddington luminosity. This is at least partly driven by a top-heavy stellar initial mass function at early cosmic times which is an efficient producer of stellar mass black holes. The implication is that supermassive black holes likely arise from seeds formed through the coalescence of 3-100 Msun mass black holes that then accrete gas produced through stellar interaction processes.Comment: 8 pages, 3 figures, submitted to the Astrophysical Journal, comments welcom