824 research outputs found
The interplay between market factors and regulation in next-generation broadband: evidence from Europe
Although many factors affect next-generation access (NGA) deployment, regulatory frameworks have the power to guide future investments, further development and, consequently, the competitiveness of a next-generation broadband market. Understanding the link between markets and regulatory requirements, therefore, is essential. Using data collected from broadband stakeholders in three markets, this paper provides an empirical analysis of this relationship. The market conditions in The Netherlands, Sweden and the United Kingdom (UK) and their roles in influencing the regulatory decisions made by the respective national regulatory authorities (NRAs) are examined. Such analysis first shows that market conditions present different priorities for regulators and policymakers. While markets with weaker incentives for investment, such as the UK, are in need of regulatory and public policy intervention, The Netherlands and Sweden require less stringent measures. Despite this, evidence shows that some level of NGA regulation is presently required in all three markets, albeit to varying degrees and with different foci. The paper then highlights the interaction of the market factors, explaining that this interrelationship is more important for policymakers than the effects of a single factor. The findings of the paper are useful for regulators in addressing the challenges of next-generation broadband deployment. --Next-generation access,Regulation,The Netherlands,Sweden,United Kingdom,Comparison
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Investigating Dielectric Properties of Sintered Polymers for Rapid Manufacturing
Selective Laser Sintering (SLS) of polymers is the leading technology in the growing field of
Rapid Manufacturing. High Speed Sintering (HSS) is a process that offers the potential to reduce
costs and processing times and thus open significant new markets for Rapid Manufactured parts.
Much academic research has been performed with respect to mechanical properties of Rapid
Manufactured parts, however the area of electrical properties has received little attention to date.
Electrical properties are obviously important in applications that will involve embedding of
circuits with Rapid Manufactured 3D objects. However electrical properties are also important
for a wide variety of electrical products where Rapid Manufactured parts can be used as housings
etc.
This paper focuses on the dielectric properties of parts made by SLS and HSS and compares
properties with those for conventionally processed polymers. Dielectric strength results show
that SLS parts are comparable with injection moulded parts, while HSS parts are inferior to SLS
parts. Dielectric constant and dissipation factor results show that HSS parts are comparable with
injection moulded parts, whilst SLS parts have superior properties. The presence of porosity
(SLS and HSS) and the presence of carbon (HSS) are suggested as reasons behind the variation in
dielectric properties when compared with injection moulded parts.Mechanical Engineerin
The control of exocytosis in sea urchin eggs
Fertilisation in the sea urchin egg is characterised by a transient increase in intracellular free calcium. This triggers the exocytosis of the cortical secretory granules which lie immediately beneath the plasma membrane, producing a structure called the fertilisation envelope. The exocytotic apparatus or cortex can be isolated and responds to the physiological trigger — Ca2+ — in vitro, it is an ideal system in which to study exocytosis directly. I have developed a method of reconstituting the exocytotic apparatus. This is a very useful technique because it allows manipulation of individual components of the system. I have used this technique to study the effects of calcium ion treatment of each component of the system. I show that this does not affect the responsiveness of subsequent reconstitution. I have investigated the mechanisms by which various compounds activate eggs and cause the increase in Ca2+, which triggers exocytosis. Using a permeabilised egg preparation I show that neither guanosine 3',5'-cyclic monophosphate (cGMP) nor guanosine 5'-O-(3-thio-triphosphate) (GTPyS—a compound which causes irreversible activation of GTP-binding proteins), directly stimulate the release of calcium from intracellular stores. Using an indirect single cell assay for DAG by measuring pH changes due to activation of a Na+/H+ antiport, I show that GTIyS but not cGMP can stimulate the enzyme phosphoinositidase C in the absence of an increased intracellular free calcium. I also show that, under the conditions of this assay, insemination fails to activate the Na+/H+ antiport. This suggests that sperm do not trigger the array of events which occur at fertilisation by interaction with GTP-binding proteins. It has been suggested that a change in the phosphorylation state is important in secretory control in many cells. I have investigated whether this also the case in the sea urchin egg by microinjecting into eggs the compound adenosine-5'-O-(3-thiotriphosphate) (ATPyS) which can be used to irreversibly phosphorylate proteins. ATPyS prevents fertilisation envelope elevation after insemination but does not prevent the sperm induced rise in intracellular free calcium. I present evidence to show that ATPyS requires the presence of cytoplasm in order to elicit its inhibitory effects. I also show that the effect is irreversible and that ATPyS is not itself the inhibitor. The results with this compound strongly suggest that a protein, when phosphorylated inhibits exocytosis in the sea urchin egg
A simplified model of the reflow soldering process
Previous models of the reflow soldering process have used
commercial finite difference (FD) or computational fluid
dynamics simulation software to create detailed
representations of the product and/or the reflow furnace. Such
models have been shown to be highly accurate at predicting
the temperatures a PCB design will achieve during the reflow
process. These models are however complex to generate and
analysis times are long, even using modern high performance
workstations. With the move to adopt lead free soldering
technology, and the consequently higher reflow process
temperatures, optimisation of the reflow profile is gaining a
renewed emphasis. This paper describes a less complex
approach to modelling of the process, which uses simplified
representations of both the product and the process, together
with a FD solver developed specifically for this application,
and which achieves an accuracy comparable with more
detailed models. In order to establish an accurate
representation of the specific reflow furnace being simulated,
a reflow logger is used to make measurements of the
temperature and level of thermal convection at each point
along the length of the furnace for a small number of carefully
chosen reflow profiles. The temperatures for any other reflow
profile can then be predicted from these measurements
Reflow soldering process simulation: a simplified model
Established models of temperature development during reflow soldering have used general purpose,
finite difference (FD) or computational fluid dynamics modelling tools to create detailed
representations of both the product and the reflow furnace. Such models have been shown to
achieve a high degree of accuracy, but are complex to generate and analysis times are long. With
the move to adopt lead free soldering technology, and the consequently higher reflow process temperatures,
optimisation of the reflow profile will gain a renewed emphasis. This paper will report
a model of the process which uses simplified representations of both the product and the process
which achieves an accuracy comparable with more detailed models. In order to establish an accurate
representation of the specific reflow furnace being simulated, a reflow logger is used to make
measurements of the temperature and level of thermal convection at each point along the length of
the furnace for a small number of carefully chosen reflow profiles. The behaviour for any other reflow
profile may then be extrapolated from these measurements
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Image processing techniques in nuclear medicine
The application of image processing techniques to radionuclide images acquired on a gamma camera - computer system has been investigated.
Hepatic perfusion imaging studies with 99Tcm-tin colloid were performed in patients with primary colorectal carcimma. The hepatic perfusion index performed poorly in the detection of those patients with occult or overt hepatic metastastes, as did mean transit times of liver colloid flow derived from deconvolution analysis. A discriminant function was developed which separated those patients with occult metastases from those without liver disease.
A fully automatic algorithm to derive a left ventricular edge from each frame of an ECG gated cardiac blood pool study was developed and validated in patient studies. Left ventricular ejection fractions calculated from count rates within the edge were reproducible and correlated well with ejection fractions derived from the same images by a manual technique, and with ejection fractions derived from left ventricular cineangiography.
Studies were performed in patients to evaluate the effectiveness of tomographic imaging of the myocardial perfusion imaging agent 99Tcm-tBIN for detection of ischaemic heart disease. Tomographic reconstructions in the planes of the axes of the left ventricle gave better results than transaxial reconstructions or planar imaging. Choice of the optimum reconstruction filter for use in tomography using 99Tcm-tBIN was examined by means of patient am phantom studies. These showed that more accurate diagnoses and better reconstructions were obtained with smoothing filters than by the use of sharp reconstruction filters.
This work shows that optimum image processing techniques must be established to attain the best possible results with new radiopharmaceuticals for nuclear medicine investigations
Micro-architecture designs and methods for eager execution and fetching of instructions
Micro-architecture designs and methods are provided. A computer processing architecture may include an instruction cache for storing producer instructions, a half-instruction cache for storing half instructions, and eager shelves for storing a result of a first producer instruction. The computer processing architecture may fetch the first producer instruction and a first half instruction; send the first half instruction to the eager shelves; based on execution of the first producer instruction, send a second half instruction to the eager shelves; assemble the first producer instruction in the eager shelves based on the first half instruction and the second half instruction; and dispatch the first producer instruction for execution.https://digitalcommons.mtu.edu/patents/1155/thumbnail.jp
Internet of Things (IoT) enabled assistive care services: Designing for value and trust
The rising elderly demographic, often with long-term conditions, represents a significant challenge globally in terms of planning for the efficient use of increasingly expensive and constrained health care resources. The internet of things (IoT) emerged as a disruptive and transformative new technology that could potentially stimulate development of new innovative assisted living health and care services. In this paper, we argue that as the human agency and relationship intrinsically associated with care get transferred to the material agency of smart technology, value and trust should be a vital consideration for designing such services.Drawing on interdisciplinary perspectives from the literature on services innovation, design science and trust in relation to healthcare technologies, we present a conceptual framework that articulates various levels of trust among the concerned stakeholders in the service ecosystem and suggests value-sensitive design considerations, anchored on the principles of trust, for future IoT-enabled assistive care services
Thermal design of high power semiconductor packages for aircraft electronic systems
The More Electric Aircraft is likely to require more extensive use of power electronics, for which thermal management will be a key issue. This paper presents an approach to designing integrated air cooled heatsinks which is being developed by Loughborough University as part of the CARAD funded Variable Frequency to Constant Frequency (VFCF) Converter project in collaboration with project partners TRW Aeronautical Systems, Mitel Semiconductor, AEA Technology and BAe Airbus. The paper shows how simple models of the heat transfer from heatsink fins, which are based on well established empirical correlations, may be utilised in combination with either simple analytical models or two dimensional finite element models of the heat conduction from the semiconductor die through the multilayer package structure to the base of the fins. These models allow the generation of design curves which may be used to rapidly explore a wide range of design options before selecting potential designs for more detailed evaluation using 3D FE analysis. In systems such as a VFCF convertor the semiconductor devices are switched at high frequency to ensure good input and output current waveforms. The power dissipated in the semiconductors, and therefore the heatsink weight, will however increase with the switching frequency, whereas the associated filtering components will be smaller and lighter at higher frequencies. The optimisation of the overall system weight therefore involves a tradeoff between the heatsinking and filtering requirements rather than just determining the optimum heatsink design for a specific power dissipatio
Designing sustainable business models for telehealthcare services adoption: A critical realism informed case study approach
A rising elderly population in England, together with the prevalence of long-term chronic health conditions and higher demands for social care, raise significant issues in terms of financing the provision of telehealthcare services. These emerging technologies can potentially provide more meaningful opportunities for operational efficiency and cost savings by supporting ‘ageing in place’, as opposed to an increasing reliance on commissioning expensive institutional provisions such as care homes. Accordingly, policymakers advocate the provision and implementation of telehealthcare services on an increased population scale. This study employs an investigative framework that brings together two interdisciplinary and complementary theoretical frames, synthesised from the existing literature on business models and service innovation. Using the principles of Critical Realism (CR) to inform a qualitative case study research design, we empirically contextualise our value-driven investigative framework and present our findings that identify four main themes, namely (i) Nature of the service, (ii) Advocacy and collaborations, (iii) Organisational characteristics, and (iv) Technology and Information systems. These four themes emerging from the empirical investigation concern value proposition, value co-creation and value realisation within a service and inform our next stage of CR analysis – to unearth the hidden structures and causal mechanisms and to better explain the underlying reality within a service ecosystem
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