The effect of age on referral to and use of specialist palliative care services in adult cancer patients: a systematic review

Objective: to investigate variations in the use of specialist palliative care (SPC) services for adult cancer patients, in relation to age.Design: systematic review of studies examining use of or referral to SPC services in adult cancer patients.Search strategy and selection criteria: six electronic databases (Medline, Embase, Web of Science, HMIC, SIGLE and AgeInfo) were searched for studies published between 1966 and March 2005, and references in the articles identified were also examined. Inclusion criteria were all studies which provided data on age in relation to use of or referral to SPC. Two reviewers independently selected studies, extracted data and assessed methodological quality according to defined criteria.Main outcome measures: use of or referral to SPC services, determined from all sources of report (patient, informal carer, health care professional, health care records).Results: 14 studies were identified. All reported a statistically significant lower use of SPC among older cancer patients (65 and above or older) at a univariate level [crude odds ratios ranged from 0.33 (0.15-0.72) to 0.82 (0.80-0.82)]. However, there were important methodological weaknesses in all of the studies identified; most crucially, studies failed to consider variations in use in relation to need for SPC.Conclusions: there is some evidence that older people are less likely to be referred to, or to use, SPC. These findings require confirmation in studies using prospectively collected data which control for patient's need for SPC

Comparisons of the execution times and memory requirements for high-speed discrete fourier transforms and fast fourier transforms, for the measurement of AC power harmonics

Conventional wisdom dictates that a Fast Fourier Transform (FFT) will be a more computationally effective method for measuring multiple harmonics than a Discrete Fourier Transform (DFT) approach. However, in this paper it is shown that carefully coded discrete transforms which distribute their computational load over many frames can be made to produce results in shorter execution times than the FFT approach, even for large number of harmonic measurement frequencies. This is because the execution time of the presented DFT actually rises with N and not the classical N2 value, while the execution time of the FFT rises with Nlog2N

Roles, service knowledge and priorities in the provision of palliative care: a postal survey of London GPs

Objectives: To explore general practitioners' (GPs) current involvement in and attitudes towards the provision of palliative care in primary care. Methods: Postal survey of 356 London-based GPs, assessing attitudes towards palliative care provision, district nursing and specialist palliative care services, and priorities for future service development. Results: Currently, 65% of GPs were providing palliative care to patients on their list; 72% agreed or strongly agreed palliative care was a central part of their role; and 27% wanted to hand care over to specialists. Most GPs (66%) disagreed with the statement that 'palliative care is mainly district nursing (DN) work'. Many were unaware of out-of-hours DN and specialist palliative care services. Multi-variable analysis found four GP characteristics - larger practice size, more years experience as a GP, receipt of palliative care education, and current provision of palliative care - were associated with agreement that palliative care was central to a GP's role. Conclusion: A minority of NHS GPs in London would rather have no involvement in palliative care in primary care. Knowledge of current services for palliative care is generally poor among GPs. These findings highlight potential gaps in services, particularly in small practices. Specialists will need to consider these factors in working with GPs to develop primary palliative care and to enable greater access to specialist palliative care

Frequency and fundamental signal measurement algorithms for distributed control and protection applications

Increasing penetration of distributed generation within electricity networks leads to the requirement for cheap, integrated, protection and control systems. To minimise cost, algorithms for the measurement of AC voltage and current waveforms can be implemented on a single microcontroller, which also carries out other protection and control tasks, including communication and data logging. This limits the frame rate of the major algorithms, although analogue to digital converters (ADCs) can be oversampled using peripheral control processors on suitable microcontrollers. Measurement algorithms also have to be tolerant of poor power quality, which may arise within grid-connected or islanded (e.g. emergency, battlefield or marine) power system scenarios. This study presents a 'Clarke-FLL hybrid' architecture, which combines a three-phase Clarke transformation measurement with a frequency-locked loop (FLL). This hybrid contains suitable algorithms for the measurement of frequency, amplitude and phase within dynamic three-phase AC power systems. The Clarke-FLL hybrid is shown to be robust and accurate, with harmonic content up to and above 28% total harmonic distortion (THD), and with the major algorithms executing at only 500 samples per second. This is achieved by careful optimisation and cascaded use of exact-time averaging techniques, which prove to be useful at all stages of the measurements: from DC bias removal through low-sample-rate Fourier analysis to sub-harmonic ripple removal. Platform-independent algorithms for three-phase nodal power flow analysis are benchmarked on three processors, including the Infineon TC1796 microcontroller, on which only 10% of the 2000 mus frame time is required, leaving the remainder free for other algorithms

Tradeoffs between AC power quality and DC bus ripple for 3-phase 3-wire inverter-connected devices within microgrids

Visions of future power systems contain high penetrations of inverters which are used to convert power from dc (direct current) to ac (alternating current) or vice versa. The behavior of these devices is dependent upon the choice and implementation of the control algorithms. In particular, there is a tradeoff between dc bus ripple and ac power quality. This study examines the tradeoffs. Four control modes are examined. Mathematical derivations are used to predict the key implications of each control mode. Then, an inverter is studied both in simulation and in hardware at the 10 kVA scale, in different microgrid environments of grid impedance and power quality. It is found that voltage-drive mode provides the best ac power quality, but at the expense of high dc bus ripple. Sinusoidal current generation and dual-sequence controllers provide relatively low dc bus ripple and relatively small effects on power quality. High-bandwidth dc bus ripple minimization mode works well in environments of low grid impedance, but is highly unsuitable within higher impedance microgrid environments and/or at low switching frequencies. The findings also suggest that the certification procedures given by G5/4, P29 and IEEE 1547 are potentially not adequate to cover all applications and scenarios

Impact of marine power system architectures on IFEP vessel availability and survivability

In recent years integrated full electric propulsion (IFEP) has become a popular power system concept within the marine community, both for the naval and the commercial community. In this paper the authors discuss the need for a detailed investigation into the impact of different IFEP power system architectures on the availability of power and hence on the survivability of the vessel. The power system architectures considered here could relate to either a commercial or a naval vessel and include radial, ring and hybrid AC/DC arrangements. Comparative fault studies of the architectures were carried out in an attempt to make valuable observations on the survivability of a vessel. Simulation results demonstrate that the ring and hybrid AC/DC architectural contribute to a higher survivability than the radial architecture. However, there are still challenges that need to be addressed and therefore potential solutions such as fault current limiters will be considered

Benchmarking and optimisation of Simulink code using Real-Time Workshop and Embedded Coder for inverter and microgrid control applications

When creating software for a new power systems control or protection device, the use of auto-generated C code via MATLAB Simulink Real-Time Workshop and Embedded Coder toolboxes can be a sensible alternative to hand written C code. This approach offers the benefits of a simulation environment, platform independence and robust code. This paper briefly summarises recent experiences with this coding process including the pros and cons of such an approach. Extensive benchmarking activities are presented, together with descriptions of simple (but non-obvious) optimisations made as a result of the benchmarking. Examples include replacement of certain Simulink blocks with seemingly more complex blocks which execute faster. "S functions" are also designed for certain key algorithms. These must be fully "in-lined" to obtain the best speed performance. Together, these optimisations can lead to an increase in execution speed of more than 1.4x in a large piece of auto-generated C code. An example is presented, which carries out Fourier analysis of 3 signals at a common (variable) frequency. The overall speed improvement relative to the baseline is 2.3x, of which more than 1.4x is due to non-obvious improvements resulting from benchmarking activities. Such execution speed improvements allow higher frame rates or larger algorithms within inverters, drives, protection and control applications

Increasing security of supply by the use of a local power controller during large system disturbances

This paper describes intelligent ways in which distributed generation and local loads can be controlled during large system disturbances, using Local Power Controllers. When distributed generation is available, and a system disturbance is detected early enough, the generation can be dispatched, and its output power can be matched as closely as possible to local microgrid demand levels. Priority-based load shedding can be implemented to aid this process. In this state, the local microgrid supports the wider network by relieving the wider network of the micro-grid load. Should grid performance degrade further, the local microgrid can separate itself from the network and maintain power to the most important local loads, re-synchronising to the grid only after more normal performance is regained. Such an intelligent system would be a suitable for hospitals, data centres, or any other industrial facility where there are critical loads. The paper demonstrates the actions of such Local Power Controllers using laboratory experiments at the 10kVA scale

Architecture of a network-in-the-Loop environment for characterizing AC power system behavior

This paper describes the method by which a large hardware-in-the-loop environment has been realized for three-phase ac power systems. The environment allows an entire laboratory power-network topology (generators, loads, controls, protection devices, and switches) to be placed in the loop of a large power-network simulation. The system is realized by using a realtime power-network simulator, which interacts with the hardware via the indirect control of a large synchronous generator and by measuring currents flowing from its terminals. These measured currents are injected into the simulation via current sources to close the loop. This paper describes the system architecture and, most importantly, the calibration methodologies which have been developed to overcome measurement and loop latencies. In particular, a new "phase advance" calibration removes the requirement to add unwanted components into the simulated network to compensate for loop delay. The results of early commissioning experiments are demonstrated. The present system performance limits under transient conditions (approximately 0.25 Hz/s and 30 V/s to contain peak phase-and voltage-tracking errors within 5. and 1%) are defined mainly by the controllability of the synchronous generator

Thermal buoyancy on Venus: Preliminary results of finite element modeling

Enhanced surface temperatures and a thinner lithosphere on Venus relative to Earth have been cited as leading to increased lithospheric buoyancy. This would limit or prevent subduction on Venus and favor the construction of thickened crust through underthrusting. In order to evaluate the conditions distinguishing between underthrusting and subduction, we have modeled the thermal and buoyancy consequences of the subduction end member. This study considers the fate of a slab from the time it starts to subduct, but bypasses the question of subduction initiation. Thermal changes in slabs subducting into a mantle having a range of initial geotherms are used to predict density changes and thus their overall buoyancy. Finite element modeling is then applied in a first approximation of the assessment of the relative rates of subduction as compared to the buoyant rise of the slab through a viscous mantle