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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of network and systems management 2 (1994), S. 95-123 
    ISSN: 1573-7705
    Keywords: Network Restoration ; Digital Cross-Connect System (DCS) ; routing algorithms ; multicommodity flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract A crucial issue in the management of telecommunications networks is restoration after a network failure. We compare the capacity efficiency (the amount of traffic restored over fixed capacity) of several types of restoration methods for Digital Crossconnect Systems (DCSs) under both node or link failures in metropolitan networks. These restoration methods can be broadly categorized based on the type of control of the restoration process and the type of procedure for rerouting traffic around the failure. It is easily shown that point-to-point methods (where traffic is rerouted end-to-end) restore a higher percent of traffic than patch methods (where traffic is rerouted only around the failed segment). However, quantification of the difference in efficiency among the methods is important to fully evaluate other trade-offs, such as cost and speed of restoration. To evaluate the efficiency difference, we generated random network traffic distributions by simulation and then failed links and nodes for each simulation sample. Statistics were generated on the expected amount of restored traffic for each restoration method. In particular, we found that the efficiency advantage of point-to-point methods over patch methods is greater for link failure than for node failure. Also, the difference was not statistically significant in low levels of network congestion (i.e., networks with large amounts of excess capacity) and became more significant as network congestion increased.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1435-604X
    Keywords: Light propagation ; Radiation transport ; Tissue optics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This paper is the first of two reviewing the propagation of electromagnetic radiation of wavelength 0.25–10μm in tissue. After a brief discussion of light/tissue interactions, a mathematical description of light propagation in terms of radiative transfer is developed. Formal solutions of the resulting equation are outlined, but the emphasis is on approximate method of solution—namely the discrete ordinates method, the technique of functional expansion and Monte Carlo simulation. The application of the simplest of these approximate methods, namely the 2-flux and diffusion models, to tissue optics is discussed in some detail. The second paper deals with the optical properties of tissue and the salient characteristics of light fluence distributions in these tissues.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-604X
    Keywords: Tissue optics ; Absorption ; Scattering ; Fluence distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract This paper is the second of two reviewing the propagation of electromagnetic radiation of wavelength 0.25–10μm in tissue. This part begins with a discussion of how the fundamental optical interaction coefficients of tissue may be measured. Both direct methods, in which the coefficients are measured for optically thin samples, and indirect methods, in which the coefficients are inferred from measurements on bulk samples are described. The difficulties inherent in both types of measurement are outlined. Next the wavelength dependence of the scattering and absorption coefficient is discussed, both from a heuristic point of view and by illustration from current literature. We illustrate how the optical spectrum can be divided into regions where the propagation of light is dominated by absorption or scattering effects. Finally we show how the distribution of light fluence in these spectral regions is dramatically different and illustrate the important features of these distributions.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 5 (1990), S. 245-252 
    ISSN: 1435-604X
    Keywords: Photodynamic therapy ; Supratentorial tumours ; Cerebral gliomas ; Cerebral metastasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Experience with intraoperative PDT in 50 patients with malignant supratentorial tumours is reported; in 33 cases the tumour was recurrent. In 45 patients the tumour was a cerebral glioma and in five cases a solitary cerebral metastasis. There were 29 males and 17 females with an age range of 17–73 (mean 48) years. All patients received either haematoporphyrin derivative (HPD) or dihaematoporphyrin ether (DHE) 18–24 h preoperatively. A photoilluminating device, of the authors' design, was coupled to an argon dye pump laser in order to deliver light at 630 nm to a tumour cavity created by radical tumour resection and/or tumour cyst drainage. The total light energy delivered ranged from 440 to 3888 J and the light energy density ranged from 8 to 175 J/cm2. In eight patients a line fibre(s) was used to administer interstitial light as a supplement to the cavitary photoillumination. The additional light dose ranged from 60 to 945 J/cm. There were two postoperative deaths as the consequence of haematoma accumulation in the tumour resection cavity. In three patients neurological function was worse postoperatively and did not recover. Postoperative cerebral oedema was pronounced in some cases and required second craniotomy in two patients (the histology from both showed haemorrhagic necrosis of residual tumour). Four patients developed wound infections; two of these required surgical treatment. Four patients, two of whom were hemiparetic, developed deep vein thrombosis and required anticoagulant therapy. There were no adverse systemic reactions to the administration of either photosensitizer and only three skin photosensitivity reactions. Follow up ranged from 1 to 30 months. In the group of 45 patients with gliomas the death rate per observation year was 0.92 for the interval between PDT and death. For the interval between first diagnosis and death the rate was 0.41 deaths per observation year. The median survival was 8.6 months with a 1 and 2 year actuarial survival rate of 32% and 18%, repectively. In 12 patients a complete or near complete CT scan response was identified post PDT. These patients tended to have a tumour geometry (e.g. cystic) that allowed complete or near complete light distribution to the tumour. The median survival for this group was 17.1 months with a 1 and 2 year actuarial survival of 62% and 38%, respectively. In the 33 cases without a complete response the median survival was 6.5 months with a 1 and 2 year actuarial survival of 22% and 11%, respectively. Photodynamic therapy of malignant brain tumours can be carried out with acceptable risk. Good responses appear to be related to adequate light delivery to the tumour.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Lasers in medical science 1 (1986), S. 235-244 
    ISSN: 1435-604X
    Keywords: Dihaematoporphyrin ether ; Aluminium chlorosulphonated phthalocyanine ; Penetration depth ; Diffusion theory ; Photodynamic therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The additional optical absorption in tissue resulting from the uptake of exogenous photosensitizers increases the effective attenuation of photoactivating light. This may be significant for the irradiation of solid tumours in photodynamic therapy, since it reduces the depth or volume of tissue treated. The effect has been studied in vitro by using dihaematoporphyrin ether (DHE) and 630 nm light in tissues representing a wide range of absorption and scattering conditions. While the attenuation may be markedly changed by small concentrations of DHE in pure scattering media, tissues with significant inherent light absorption are little affected by the additional absorption of DHE at concentrations relevant to clinical photodynamic therapy. However, it is shown that for other potential photosensitizers such as the phthalocyanines, which have substantially greater absorption at the treatment wavelength than DHE, the penetration of light in tissues may be significantly reduced.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Higher education 13 (1984), S. 1-22 
    ISSN: 1573-174X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Nature of Science, Research, Systems of Higher Education, Museum Science
    Notes: Abstract A considerable amount of information is available concerning the adjustment problems that students from developed countries experience when they transfer from school to university. Comparatively little is known about the problems of African students, despite the existence of a number of factors which might be expected to produce large numbers of problems and relatively severe problems. Having adopted certain criteria regarding the “acceptability” or otherwise of adjustment problems, a preliminary survey was conducted at the University of Zambia in order to see whether adjustment problems existed and to give some insight into the type of problem experienced. The survey indicated the presence of a large number and wide variety of problems and a questionnaire was subsequently developed in order to test the potency, generality and persistency of the student's difficulties. The results obtained with a representative sample of 242 first-year and 60 fourth-year students showed that there are problems which are sufficiently potent, general and/or persistent to be a cause for concern to the university authorities.
    Type of Medium: Electronic Resource
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  • 7
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    Manchester University Press
    Publication Date: 2024-03-29
    Description: Golf is a major global industry. It is played by more than 60 million people worldwide, and there are more than 32,000 courses across the globe in 140 countries. This book looks at the power relationships in and around golf, examining whether the industry has demonstrated sufficient leadership on environmental matters for the government to be able to trust them to make decisions with implications for public health. It is the first comprehensive study of the varying impacts of golf on the environment, and is based on extensive empirical research, including interviews with major stakeholders in the golf industry and members of protest groups. The authors examine golf as a sport and as a global industry, drawing on three discrete literatures – the study of sport as a global social movement, environmental sociology and the study of corporate environmentalism.
    Keywords: sociology ; globalization ; corporate ; power ; environmentalism ; golf ; environment ; sport ; thema EDItEUR::J Society and Social Sciences::JH Sociology and anthropology::JHB Sociology::JHBS Sociology: sport and leisure
    Language: English
    Format: image/png
    Format: image/png
    Format: image/png
    Format: image/jpeg
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  • 8
    Publication Date: 1983-03-01
    Print ISSN: 0163-1829
    Electronic ISSN: 1095-3795
    Topics: Physics
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  • 9
    Publication Date: 2008-04-09
    Print ISSN: 0031-9155
    Electronic ISSN: 1361-6560
    Topics: Biology , Medicine , Physics
    Published by Institute of Physics
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  • 10
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