Outcomes and costs of blunt trauma in England and Wales

Background Trauma represents an important public health concern in the United Kingdom, yet the acute costs of blunt trauma injury have not been documented and analysed in detail. Knowledge of the overall costs of trauma care, and the drivers of these costs, is a prerequisite for a cost-conscious approach to improvement in standards of trauma care, including evaluation of the cost-effectiveness of new healthcare technologies. Methods Using the Trauma Audit Research Network database, we examined patient records for persons aged 18 years and older hospitalised for blunt trauma between January 2000 and December 2005. Patients were stratified by the Injury Severity Score (ISS). Results A total of 35,564 patients were identified; 60% with an ISS of 0 to 9, 17% with an ISS of 10 to 16, 12% with an ISS of 17 to 25, and 11% with an ISS of 26 to 75. The median age was 46 years and 63% of patients were men. Falls were the most common cause of injury (50%), followed by road traffic collisions (33%). Twenty-nine percent of patients were admitted to critical care for a median length of stay of 4 days. The median total hospital length of stay was 9 days, and 69% of patients underwent at least one surgical procedure. Seven percent of the patients died before discharge, with the highest proportion of deaths among those in the ISS 26–75 group (32%). The mean hospital cost per person was £9,530 (± 11,872). Costs varied significantly by Glasgow Coma Score, ISS, age, cause of injury, type of injury, hospital mortality, grade and specialty of doctor seen in the accident and emergency department, and year of admission. Conclusion The acute treatment costs of blunt trauma in England and Wales vary significantly by injury severity and survival, and public health initiatives that aim to reduce both the incidence and severity of blunt trauma are likely to produce significant savings in acute trauma care. The largest component of acute hospital cost is determined by the length of stay, and measures designed to reduce length of admissions are likely to be the most effective in reducing the costs of blunt trauma care

Microwave-induced resistance oscillations and zero-resistance states in 2D electron systems with two occupied subbands

We report on theoretical studies of recently discovered microwave-induced resistance oscillations and zero resistance states in Hall bars with two occupied subbands. In the same results, resistance presents a peculiar shape which appears to have a built-in interference effect not observed before. We apply the microwave-driven electron orbit model, which implies a radiation-driven oscillation of the two-dimensional electron system. Thus, we calculate different intra and inter-subband electron scattering rates and times that are revealing as different microwave-driven oscillations frequencies for the two electronic subbands. Through scattering, these subband-dependent oscillation motions interfere giving rise to a striking resistance profile. We also study the dependence of irradiated magnetoresistance with power and temperature. Calculated results are in good agreement with experiments.Comment: 7 pages, 6 figure

Theory of phonon-drag thermopower of extrinsic semiconducting single-wall carbon nanotubes and comparison with previous experimental data

A theoretical model for the calculation of the phonon-drag thermopower, $S^{g}$, in degenerately doped semiconducting single-wall carbon nanotubes (SWCNTs) is proposed. Detailed calculations of $S^{g}$ are performed as a function of temperature, tube radius and position of the Fermi level. We derive a simple analytical expression for $S^{g}$ that can be utilized to determine the free carrier density in doped nanotubes. At low temperatures $S^{g}$ shows an activated behavior characteristic of the one-dimensional (1D) character of carriers. Screening effects are taken into account and it is found that they dramatically reduce the magnitude of $S^{g}$. Our results are compared with previous published experimental data in bulk p-doped SWCNT materials. Excellent agreement is obtained in the temperature range 10-200 K for a consistent set of parameters. This is a striking result in view of the complexity of these systems.Comment: 21 pages, 6 figures. This version has been accepted for publication in Phys. Rev.

Performance of internal wall insulation systems - experimental test for the validation of a hygrothermal simulation tool

In the UK, transient models of heat, air and moisture transport (HAMT) are common tools used by building practitioners to better understand moisture movement within building elements and construction systems. Enforced by BS 5250:2011, hygrothermal simulations are also used for condensation risk analysis and to estimate the likelihood of mould growth and fabric decay. This paper describes the methodology applied in the validation of a hygrothermal-modelling tool used in the evaluation of internal wall insulation. Wall assemblies typically constructed for internal insulation were exposed to transient boundary conditions derived from vapour pressure profiles and their response to step changes and fluctuations were analysed. The wall assemblies were constructed using one wall substrate (aerated clay blocks and gypsum plaster) and eight commonly used internal insulation systems. Relative humidity and temperature levels measured at the interface between the wall substrate and each insulation system were used to assess the hygrothermal performance of each insulation system. As a result, the wall assemblies were clustered in three subgroups; dense capillaryactive insulation, lightweight vapour-permeable insulation and synthetic vapour-closed insulation, and the hygrothermal performance of the proposed clusters compared with the results provided by the simulation tool. It was found that simulated assemblies have similar hygrothermal performance as those monitored

Suppression of Quantum Scattering in Strongly Confined Systems

We demonstrate that scattering of particles strongly interacting in three dimensions (3D) can be suppressed at low energies in a quasi-one-dimensional (1D) confinement. The underlying mechanism is the interference of the s- and p-wave scattering contributions with large s- and p-wave 3D scattering lengths being a necessary prerequisite. This low-dimensional quantum scattering effect might be useful in "interacting" quasi-1D ultracold atomic gases, guided atom interferometry, and impurity scattering in strongly confined quantum wire-based electronic devices.Comment: 3 figs, Phys. Rev. Lett. (early November issue

Polarization immunity of magnetoresistivity response under Microwave excitation

We analyze theoretically the dependence of the microwave polarization sate and sense on the magnetoresistivity response of two-dimensional electron systems. Linear and circular polarization have been considered with different senses and directions. We discuss the polarization dependence of the longitudinal magnetoresistivity and propose an explanation for the experimentally observed polarization immunity, i.e., resistivity oscillations and zero resistance state regions are unaffected by the sense of circular polarization or by the direction of microwave electric field.Comment: 4 pages and 1 figur

Theory of Interfacial Plasmon-Phonon Scattering in Supported Graphene

One of the factors limiting electron mobility in supported graphene is remote phonon scattering. We formulate the theory of the coupling between graphene plasmon and substrate surface polar phonon (SPP) modes, and find that it leads to the formation of interfacial plasmon-phonon (IPP) modes, from which the phenomena of dynamic anti-screening and screening of remote phonons emerge. The remote phonon-limited mobilities for SiO$_{2}$, HfO$_{2}$, h-BN and Al$_{2}$O$_{3}$ substrates are computed using our theory. We find that h-BN yields the highest peak mobility, but in the practically useful high-density range the mobility in HfO$_{2}$-supported graphene is high, despite the fact that HfO$_{2}$ is a high-$\kappa$ dielectric with low-frequency modes. Our theory predicts that the strong temperature dependence of the total mobility effectively vanishes at very high carrier concentrations. The effects of polycrystallinity on IPP scattering are also discussed.Comment: 33 pages, 7 figure

Pattern Formation in Semiconductors

In semiconductors, nonlinear generation and recombination processes of free carriers and nonlinear charge transport can give rise to non-equilibrium phase transitions. At low temperatures, the basic nonlinearity is due to the autocatalytic generation of free carriers by impact ionization of shallow impurities. The electric field accelerates free electrons, causing an abrupt increase in free carrier density at a critical electric field. In static electric fields, this nonlinearity is known to yield complex filamentary current patterns bound to electric contacts

Analysis of particulate emissions from tropical biomass burning using a global aerosol model and long-term surface observations

We use the GLOMAP global aerosol model evaluated against observations of surface particulate matter (PM₂⋅₅) and aerosol optical depth (AOD) to better understand the impacts of biomass burning on tropical aerosol over the period 2003 to 2011. Previous studies report a large underestimation of AOD over regions impacted by tropical biomass burning, scaling particulate emissions from fire by up to a factor of 6 to enable the models to simulate observed AOD. To explore the uncertainty in emissions we use three satellite-derived fire emission datasets (GFED3, GFAS1 and FINN1). In these datasets the tropics account for 66-84% of global particulate emissions from fire. With all emission datasets GLOMAP underestimates dry season PM₂⋅₅ concentrations in regions of high fire activity in South America and underestimates AOD over South America, Africa and Southeast Asia. When we assume an upper estimate of aerosol hygroscopicity, underestimation of AOD over tropical regions impacted by biomass burning is reduced relative to previous studies. Where coincident observations of surface PM₂⋅₅ and AOD are available we find a greater model underestimation of AOD than PM₂⋅₅, even when we assume an upper estimate of aerosol hygroscopicity. Increasing particulate emissions to improve simulation of AOD can therefore lead to overestimation of surface PM₂⋅₅ concentrations. We find that scaling FINN1 emissions by a factor of 1.5 prevents underestimation of AOD and surface PM₂⋅₅ in most tropical locations except Africa. GFAS1 requires emission scaling factor of 3.4 in most locations with the exception of equatorial Asia where a scaling factor of 1.5 is adequate. Scaling GFED3 emissions by a factor of 1.5 is sufficient in active deforestation regions of South America and equatorial Asia, but a larger scaling factor is required elsewhere. The model with GFED3 emissions poorly simulates observed seasonal variability in surface PM₂⋅₅ and AOD in regions where small fires dominate, providing independent evidence that GFED3 underestimates particulate emissions from small fires. Seasonal variability in both PM₂⋅₅ and AOD is better simulated by the model using FINN1 emissions. Detailed observations of aerosol properties over biomass burning regions are required to better constrain particulate emissions from fires

Suppression of electron relaxation and dephasing rates in quantum dots caused by external magnetic fields

An external magnetic field has been applied in laterally coupled dots (QDs) and we have studied the QD properties related to charge decoherence. The significance of the applied magnetic field to the suppression of electron-phonon relaxation and dephasing rates has been explored. The coupled QDs have been studied by varing the magnetic field and the interdot distance as other system parameters. Our numerical results show that the electron scattering rates are strongly dependent on the applied external magnetic field and the details of the double QD configuration.Comment: 13 pages, 6 figure