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Showing papers on "Literature survey published in 1997"


Journal ArticleDOI
TL;DR: This contribution summarizes recent work in the field of lot sizing and scheduling and explains differences of formal models and provides some first readings recommendations on capacitated, dynamic, and deterministic cases.

606 citations


Journal ArticleDOI
TL;DR: The two-phase resource dynamics hypothesis of plant interactions along productivity gradients is based on the fact that soil resources are usually supplied in pulses rather than continuously, as assumed by most formal theory for community dynamics of terrestrial plants as mentioned in this paper.
Abstract: I Whether or not competition intensity increases or is similar along productivity gradients has been highly controversial for a number of years, but empirical results bearing on this question are quite variable and no consistent answer has yet emerged. We have developed a more general hypothesis that includes these contradictory predictions as special cases that apply under different types of resource dynamics and different types of interactions between the growth and survival components of fitness. 2 The two-phase resource dynamics hypothesis of plant interactions along productivity gradients is based on the fact that soil resources are usually supplied in pulses rather than continuously, as assumed by most formal theory for community dynamics of terrestrial plants. When soil resource supply is temporally variable, individual plants will experience two distinct phases of resource availability: pulse periods when resources are high and most growth and resource accumulation occurs, and interpulse periods when resources are too low for most plants to take up and most mortality due to resource deficits takes place. 3 Competitive effects on growth should occur during pulses at both high and low productivity. In productive environments, interpulse intervals should be relatively mild and infrequent and therefore competitive effects during pulses will usually be important for individual and population persistence. However, as productivity decreases, the frequency of pulses (as well as or in place of their magnitude) often decreases and the duration of interpulse periods increases. Therefore, we suggest that processes occurring during interpulse intervals become increasingly important for individual and population persistence as interpulse intervals become longer. Whether or not competition occurs under low productivity will then depend on (i) the extent to which the asymptotically low resource availability during interpulse periods is determined by plant uptake or by abiotic factors such as leaching, drainage, evaporation and volatization, and (ii) the extent to which decreased growth due to competition during pulses results in decreased survival during interpulse periods. 4 According to the two-phase resource dynamics hypothesis, Grime's hypothesis that competition is unimportant at low productivity will hold when soil resource availability between pulses in unproductive environments is controlled by abiotic factors and when survival during interpulse intervals is independent of or even negatively correlated with growth during pulse periods. In contrast, Newman's and Tilman's hypothesis that competition is equally important along productivity gradients will apply when either of these conditions is not true. We predict that the conditions for Grime's hypothesis to apply are more likely for productivity gradients driven by water than by mineral nutrients and when response to competition is measured for community structure or individual survival rather than for individual growth. 5 We tested the predictions about water vs. nutrient gradients and growth vs. survival or community structure responses using data from a literature survey on field and

369 citations


01 Jan 1997
TL;DR: In this article, the authors present the results of a three-year collaborative project between the British Geological Survey and the Environment and Energy Management Agency (EMEA) to collect, collate and present information concerning the physical hydraulic properties of the minor aquifers in England and Wales.
Abstract: This report is the result of a three-year collaborative project between the British Geological Survey and the Environment Agency. The aim of the project has been to collect, collate and present information concerning the physical hydraulic properties of the minor aquifers in England and Wales. These properties include hydraulic conductivity, porosity, transmissivity and storage coefficient. In addition, specific capacity (yield per unit drawdown) values are included for many of the formations described, together with yields for those formations where aquifer properties data are sparse. Although the parameters studied were limited in number, the study has proven to be complex for several reasons. Firstly the aquifers themselves are hydraulically complicated. They are bodies of rock, sometimes with indeterminate boundaries, which are heterogeneous either because of sedimentological factors in the case of the Cainozoic aquifers, or because of the effects of fracturing in older formations. This heterogeneity presents several problems. Firstly, hydraulic tests on such materials often violate the classical assumptions used in the test analysis, and the complexity of the aquifers makes interpolation between data points difficult. Secondly, the physical properties of the aquifers are often scale dependent, so that the value of a parameter at one scale may not be appropriate for use at a larger or smaller scale. Thirdly, there are problems of data quality and quantity which are particularly significant for these smaller aquifers. The quality of the pumping tests is variable and many results are from short duration pumping tests which are designed more to assess the yields of boreholes than to examine the properties of the aquifer. Also, data can be very irregularly distributed, being a product mainly of the evolving requirements of groundwater users and not of well-planned resource assessments. This irregular spacing can be both vertical as well as lateral, as in the case of thick structurally complex sequences with only scattered productive horizons. Awareness of these inherent hydrogeological factors dictated the project’s approach, which was to collect both data and knowledge about the aquifers. This permits the report to describe not only the magnitudes and variability of the aquifer parameters at a given tested locality, but also to provide some insight into factors controlling the properties, so that the results can be more confidently extrapolated. Project resources were therefore initially employed in data collection. This involved a detailed search through Agency records, with additional information from BGS, published and unpublished literature. Most of the data obtained were from analysed pumping tests, the results of which were entered in a database. The latter originally housed data on the major aquifers, collected under a preceding project, but the database needed to be significantly altered and expanded so as to manage efficiently the much larger number of aquifers involved. It was also linked with the BGS Core Analysis Database. The result comprises the National Aquifer Properties Database which is now a major UK geoscience resource, with data from more than 8000 pumping test analyses at over 8250 sites. The second main strand of the project was the collection and summarising of knowledge about the aquifers. In addition to the collection of reports of hydrogeological studies and a literature survey, expert opinion was canvassed. The latter is a vital source of information that is not often published. The results of these two approaches are synthesised in this report. After the introductory sections each chapter takes the form of a detailed review of the physical properties of a group of minor aquifers, subdivided as appropriate on stratigraphic or geographical grounds. The chapters are arranged in order of increasing age. The purpose of the review is to present the magnitudes and variability of the data (mainly from the database, but with other examples) in the context of current understanding of the aquifer systems involved and the controls on the data. To that end the review includes geological, geographical and physical hydrogeological aspects of the aquifers. Useful summaries of data from the database are included on the accompanying CD-ROM. The intention of the report is therefore to acquaint the reader with the aquifer properties data values that characterise the aquifers in the context of what is known about the complexities of their hydraulic structure and the physical controls on the data. The reader is specifically dissuaded from taking raw values out of context. A further purpose of the report is provide a comprehensive set of references by which the reader can obtain more detailed information about particular areas of interest in an aquifer. As a result of the collection and review of information about the physical properties of the minor aquifers in England and Wales, it is apparent that there are many areas in which knowledge is inadequate. For example, a critical comparison of the equivalent aquifer systems in the London and Hampshire basins was not possible in other than the most general terms. Similarly, the lateral variability in aquifer properties in the Lower Cretaceous aquifers of the Weald is suspected to arise partly from fault-controlled compartmentalisation, but the role of the faults is not well enough understood for predictive purposes. For all the effort expended on geological characterisation over almost two centuries of detailed study of English Jurassic rocks, the flow systems of the numerous arenaceous and carbonate minor aquifers of that system are in general poorly characterised. Very localised borehole development and the effects of tapping complex multi-aquifer sequences mean that the fracture-dominant, structurally-affected systems of older rocks of Palaeozoic age are in many cases barely conceptualised. Such gaps in our knowledge are inevitable considering the paucity of data. Nevertheless, the project has provided the first opportunity to review comprehensively the aquifer properties of this second rank of British aquifers whose role is so important in providing local sources of water supply for both private and public use.

354 citations


Journal ArticleDOI
TL;DR: Recognition memory impairment is a robust feature of human amnesia, even when damage is limited primarily to the hippocampus, and it is shown that recognition memory is impaired after damage limited to the hippocampal region.
Abstract: A recent literature survey of results from a widely used recognition memory test raised questions about the extent to which recognition memory impairment ordinarily occurs in human amnesia and, in particular, whether recognition memory is impaired at all after damage limited to the hippocampal region (J. P. Aggleton & C. Shaw, 1996). Experiment 1 examined the performance of 6 amnesic patients on 11 to 25 different recognition memory tests. Three patients had bilateral lesions limited primarily to the hippocampus (G.D.) or the hippocampal formation (W.H. and L.M.), as determined by postmortem, neurohistological analysis (N. Rempel-Clower, S. M. Zola, L. R. Squire, & D. G. Amaral, 1996). All 6 patients exhibited unequivocally impaired recognition memory. In Experiment 2, the 3 patients still available for study were each markedly impaired on a test of object recognition similar to the kind used to test recognition memory in nonhuman primates. Recognition memory impairment is a robust feature of human amnesia, even when damage is limited primarily to the hippocampus.

288 citations


Journal ArticleDOI
TL;DR: The flowers that cease to be attractive to pollinators, shortly following pollination, tend to be from families that are known mainly to comprise species in which flower longevity, petal colour, or flower closure, is sensitive to exogenous ethylene, indicating that the effect of pollination on floral attraction is generally mediated by endogenous ethylene.
Abstract: The end of a flower's attraction to pollinators may be due to a range of visible cues such as permanent flower closure, a colour change, and withering or abscission of the petals. Floral attraction may be reduced by pollination. Pollination-induced conclusion of floral attraction is often due to a colour change or to flower closure. This may or may not be followed by a reduction in floral longevity, defined as the time to petal withering, wilting or shattering. In a few species floral longevity is increased following pollination-induced flower closure or a pollination-induced change in colour. Floral attraction, therefore, has to be distinguished from floral longevity. A literature survey shows that pollination rapidly reduces floral attraction in numerous orchids, but among other plant families only about 60 genera have been found to show pollination-induced shortening of floral attraction. Although only a few species have been investigated, it was invariably established that the effect of pollination is blocked by inhibitors of ethylene synthesis or ethylene perception, hence is mediated by ethylene. The flowers that cease to be attractive to pollinators, shortly following pollination, tend to be from families that are known mainly to comprise species in which flower longevity, petal colour, or flower closure, is sensitive to exogenous ethylene. This indicates that the effect of pollination on floral attraction is generally mediated by endogenous ethylene. Numerous species reportedly show a decrease in the period of floral attraction after exposure to ethylene, whereas only for a small number of species a decrease in the period of floral attraction induced by pollination has been observed. This discrepancy may be due to the greater attention that has been paid to the effects of ethylene. Nonetheless, the possibility remains that endogenous ethylene has a role in changing perianth form and colour in addition to signalling the occurrence of pollination.

176 citations


Journal ArticleDOI
TL;DR: In this paper, the authors reported new experimental results on the solubility of Pt in silicate melts at one atmosphere total pressure, with two different melt compositions: an anorthitediopside eutectic and a CaO-free system (3SiO 2 ·MgO·Al 2 O 3, by weight).

162 citations


Journal ArticleDOI
TL;DR: In this article, a comparative study on the effects of single air pollutants on the corrosion of copper, zinc and aluminium under realistic test conditions is presented. And the results from gravimetric evaluation are also reported.

155 citations


Journal ArticleDOI
TL;DR: This work describes four patients and their dramatic clinical and hemodynamic response to treatment with prednisone when symptomatic measures failed and a novel approach for symptomatic antiphospholipid syndrome (APS) related valvulopathy involves treatment with systemic corticosteroid.

149 citations


Journal ArticleDOI
TL;DR: In this paper, a literature survey including all experimental papers on fractals which appeared in the six Physical Review journals (A\char21{}E and Letters) during the 1990s shows that experimental reports of fractal behavior are typically based on a scaling range $\ensuremath{\Delta}$ that spans only 0.5
Abstract: Fractal structures appear in a vast range of physical systems. A literature survey including all experimental papers on fractals which appeared in the six Physical Review journals (A\char21{}E and Letters) during the 1990s shows that experimental reports of fractal behavior are typically based on a scaling range $\ensuremath{\Delta}$ that spans only 0.5\char21{}2 decades. This range is limited by upper and lower cutoffs either because further data are not accessible or due to crossover bends. Focusing on spatial fractals, a classification is proposed into (a) aggregation, (b) porous media, (c) surfaces and fronts, (d) fracture, and (e) critical phenomena. Most of these systems [except for class (e)] involve processes far from thermal equilibrium. The fact that for self-similar fractals [in contrast to the self-affine fractals of class (c)] there are hardly any exceptions to the finding of $\ensuremath{\Delta}l~2$ decades, raises the possibility that the cutoffs are due to intrinsic properties of the measured systems rather than the specific experimental conditions and apparatus. To examine the origin of the limited range we focus on a class of aggregation systems. In these systems a molecular beam is deposited on a surface, giving rise to nucleation and growth of diffusion-limited-aggregation-like clusters. Scaling arguments are used to show that the required duration of the deposition experiment increases exponentially with $\ensuremath{\Delta}$. Furthermore, using realistic parameters for surfaces such as Al(111) it is shown that these considerations limit the range of fractal behavior to less than two decades in agreement with the experimental findings. It is conjectured that related kinetic mechanisms that limit the scaling range are common in other nonequilibrium processes that generate spatial fractals.

147 citations


Journal ArticleDOI
TL;DR: In this paper, the thermal properties of Th0 2 and Th 1− y PU y O 2 were evaluated using a limited amount of data, as a result a critical evaluation is not possible.

147 citations


Journal ArticleDOI
TL;DR: From the fragmented data available for the prokaryotic glycoproteins, similarities with the eukaryotic system can be noticed.
Abstract: Rather recently it has become clear that prokaryotes (Archaea and Bacteria) are able to glycosylate proteins. A literature survey revealed the different types of glycoproteins. They include mainly surface layer (S-layer) proteins, flagellins, and polysaccharide-degrading enzymes. Only in a few cases is structural information available. Many different structures have been observed that display much more variation than that observed in eukaryotes. A few studies have given evidence for the function of the prokaryotic glycoprotein glycans. Also from the biosynthetic point of view, information is rather scarce. Due to their different cell structure, prokaryotes have to use mechanisms different from those found in eukaryotes to glycosylate proteins. However, from the fragmented data available for the prokaryotic glycoproteins, similarities with the eukaryotic system can be noticed.

Journal ArticleDOI
TL;DR: This article looks at a specific instance of traffic dispersion in communication networks, where the processes are communication processes, and the resource is the link capacity in a packet switched network.
Abstract: Aggregation of resources is a means to improve performance and efficiency in statistically shared systems in general, and communication networks in particular. One approach to this is traffic dispersion, which means that the traffic from a source is spread over multiple paths and transmitted in parallel through the network. Traffic dispersion may help in utilizing network resources to their full potential, while providing quality-of-service guarantees. It is a topic gaining interest, and much work has been done in the field. The results are, however, difficult to find, since the technique appears under many different labels. This article is therefore an attempt to gather and report on the work done on traffic dispersion in communication networks. It looks at a specific instance of this general method. The processes are communication processes, and the resource is the link capacity in a packet switched network.

Journal ArticleDOI
TL;DR: In this article, the authors examine key factors which affect make-or-buy decisions in research and development (R&D) settings-whether technology is developed in house or acquired from external sources (e.g., through licensing or R&D contracts).
Abstract: This paper examines key factors which affect make-or-buy decisions in research and development (R&D) settings-whether technology is developed in house or acquired from external sources (e.g., through licensing or R&D contracts). The paper constructs several hypotheses from the literature survey and discussions and tests these hypotheses by using data from small technology based firms in the United States and Japan. Our analyses show external technology acquisitions are more likely to be practiced when the number of rivals expected to develop a similar product is greater, and the needed technology is less related to a firm's core technology. Our analyses also imply two qualitatively different goals in external technology acquisitions: to shorten development time, and thereby reap short-term profits (short-term strategy), and to maximize long-term profits over the life of the innovation (long-term strategy). Our analyses suggest the dominance of the former strategy.

Journal ArticleDOI
TL;DR: A patient with chronic asthma who developed numbness of head, facial angioedema, and wheezing after application of fenugreek paste to her scalp as a treatment for dandruff has enlarged the list of food allergens with the addition of fENugreek.
Abstract: Background Allergic reactions after consumption of spices are well known. In Asia, fenugreek seeds are consumed as spices and also as medicines. Literature survey carried out does not reveal reports of allergic reactions to fenugreek. In our survey carried out on patients with food allergy, we found two cases of severe allergy to fenugreek. Methods We report here two cases of immediate allergy following ingestion, inhalation, and external application of fenugreek seed powder. In the first case, inhalation of the fenugreek seed powder resulted in rhinorrhea, wheezing, and fainting. The second case was of a patient with chronic asthma who developed numbness of head, facial angioedema, and wheezing after application of fenugreek paste to her scalp as a treatment for dandruff. Skin scratch test was performed with fenugreek and other members of the Leguminosae family as fenugreek also belongs to Leguminosae. Objective evidence of the reaction was obtained by conducting double-blind placebo-controlled challenges (DBPCFC). For detecting IgE binding by immunoblotting method, the proteins of the fenugreek extract were resolved using sodium dodecyl sulphate polyacrylamide gel electrophoresis. Results Skin scratch tests for the patients revealed strong sensitivity to fenugreek and chickpeas. None of the controls showed such response with fenugreek extract. During DBPCFC, both patients showed >20% drop in peak flow rate after consumption of fenugreek and chickpea. Immunoblots demonstrated binding of specific IgE from the patients' sera with the protein from extracts between 20 to 70 kD bands. Conclusion This case report has enlarged the list of food allergens with the addition of fenugreek.

Journal ArticleDOI
TL;DR: The results of an ethnobotanical survey of the plant species used in the treatment of malaria in the Brazilian State of Roraima are presented and the plants are currently undergoing laboratory screening for anti-malarial activity and toxicity.
Abstract: Malaria is probably the most serious health problem facing northern Amazonia, and isolated populations can benefit greatly from the knowledge of local resources which may effectively be used to control it. The results of an ethnobotanical survey of the plant species used in the treatment of malaria in the Brazilian State of Roraima are presented. Fieldwork was carried out amongst seven savanna-and forest-dwelling indigenous groups, and among the Luso-Brazilian population. Ninety-nine species, of 82 genera and 41 families, were identified as having been used for this purpose in the region. The results are discussed in the context of previously published information on anti-malarial plants of northern Latin America, which was analysed by a broad literature survey whose overall results are also presented here. Of the species collected in Roraima, only 24 appear previously to have been reported as anti-malarials, although 49% of the represented genera are known to be used in this way elsewhere. The plants are currently undergoing laboratory screening for anti-malarial activity and toxicity.

Journal ArticleDOI
TL;DR: A survey of the development studies literature dealing with the connections between social structure, politics and the emergence or development of "indigenous" capitalism in developing countries can be found in this paper.
Abstract: This survey critically examines the development studies literature dealing with the connections between social structure, politics and the emergence or development of ‘indigenous’ capitalism in developing countries. This literature has focused mainly on the apparent absence or weakness of indigenous capitalism, and on a set of questions and problems assumed to some degree to be generic to the ‘Third World’. Most of it has been framed by three major paradigms: the concept of ‘social barriers ‘ to capitalism; Marxian concerns about connections between economic and political domination; and a (neo‐liberal) notion that ‘politics’ necessarily constitutes an obstacle to capitalist growth. The conclusion is that these paradigms, and the underlying assumption of a generic Third World problem of weak indigenous capitalism, have ceased to be very fruitful. In this area of enquiry, development studies has run out of intellectual steam. Researchers interested in developing countries can usefully connect with recent s...

Journal ArticleDOI
15 Nov 1997-Cancer
TL;DR: The proportion of familial testicular cancer was analyzed in a prospective multicentric study involving 1692 patients and the median ages of patients with and without a family history of the disease were compared.
Abstract: BACKGROUND Undescended testes and antecedent testicular tumor are recognized risk factors for testicular germ cell cancer. It has been suggested that a family history of testicular cancer constitutes another major risk indicator. This postulation is mainly based on clinical observations and on very few systematic investigations. In the current study, the authors analyzed the proportion of familial testicular cancer in their study population and estimated the relative risk created by a family history of the disease. METHODS The proportion of familial testicular cancer was analyzed in a prospective multicentric study involving 1692 patients. The median ages of patients with and without a family history of the disease were compared. In a different patient population consisting of 518 patients and 531 age-matched controls, the frequency of family history was investigated and the relative risk calculated. In addition, a literature survey was performed to look for previous systematic reports on familial testicular cancer. RESULTS In the prospective study, 18 patients (1.1%; 95% confidence interval, 0.63-1.68%) had a first-degree relative afflicted with testicular cancer. Age at presentation was not significantly different between patients with a family history and those without. In the retrospective series, the proportion of those with a family history was 1.7% (95% confidence interval [CI], 0.80-3.27%). There was a 3.1-fold increased relative risk (95% CI, 0.77-17.95) for first-degree relatives of patients with testicular cancer. Ten previous reports on familial testicular cancer were identified in the literature. Combining the results of those previous reports and the current study led to a weighted mean prevalence of familial testicular cancer of 1.35% (95% CI, 1.12-1.58%). CONCLUSIONS The current study underscores that susceptibility to testicular germ cell cancer is influenced by genetic factors. A family history of testicular cancer is encountered in about 1.35% of patients. The relative risk for first-degree relatives of patients with the disease is increased by a factor of 3-10. Cancer 1997; 80:1954-60. © 1997 American Cancer Society.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the relationship between the quantity measured in opposed-nozzle devices and the true extensional viscosity of low-viscosity liquids and found that the relationship is not as strong as it appears.
Abstract: Opposed-nozzle devices are widely used to try to measure the extensional viscosity of low-viscosity liquids. A thorough literature survey shows that there are still several unanswered questions on the relationship between the quantity measured in opposed-nozzle devices and the “true” extensional viscosity of the liquids. In addition to extensional stresses, opposed nozzle measurements are influenced by dynamic pressure, shear on the nozzles, and liquid inertia. Therefore the ratio of the apparent extensional viscosity that is measured to the shear viscosity that is independently measured is greater than three even for Newtonian liquids. The effect of inertia on the extensional measurements is analyzed by computer-aided solution of the Navier-Stokes system, and by experiments on low-viscosity Newtonian liquids (1 mPa s

Journal ArticleDOI
07 Jun 1997-BMJ
TL;DR: This article is based on a literature survey of the field since 1980, recent monographs and review series that cover the thalassaemia field, and a detailed appraisal of the statistical analysis of the validity of screening techniques.
Abstract: The thalassaemias, the commonest monogenic diseases, are a family of inherited disorders of haemoglobin synthesis characterised by a reduced output of one or other of the globin chains of adult haemoglobin. They are likely to pose an increasing health problem for many developing countries during the early part of the new millennium.1 This review focuses mainly on their control and management, a subject of increasing importance not only for parts of the world in which the disease is particularly common but for any country which has an immigrant population from these regions. This article is based on a literature survey of the field since 1980, recent monographs2 3 and review series4 that cover the thalassaemia field, and a detailed appraisal of the statistical analysis of the validity of screening techniques.5 Various aspects of the disease were discussed at the 26th congress of the International Society of Haematology held in Singapore in August 1996, the published proceedings of which provide a valuable, up to the minute account of some aspects of current practice.6 7 8 9 10 All the human haemoglobins consist of two different pairs of globin chains combined with haem, the iron containing moiety that binds oxygen. Embryonic haemoglobin has ζ chains and γ chains (ζ2γ2); fetal haemoglobin, the synthesis of which continues throughout fetal life and declines after birth, has α chains and γ chains (α2γ2), and in adults there is a major component called haemoglobin A (α2s2) and a minor fraction, haemoglobin A2 (α2δ2). The α-like chains–that is, ζ and α–are controlled by genes at the tip of the short arm of chromosome 16 and the genes that control the γ, γ, s, and δ chains form a linked cluster on chromosome 11 in the order γ, γ, δ, s. Both the …

Journal ArticleDOI
TL;DR: The maximum holding time (MHT) was categorically studied to analyze its influence on postures, classify postures based on MHT and to develop ergonomic recommendations for MHT of categories of postures.

Journal ArticleDOI
TL;DR: In this paper, the investment principle is used to predict the optimum size increase at each moult, under simplifying assumptions such as the scaling of feeding rate with size, the efficiency of moulting, and the optimum increase at the preceding moult.
Abstract: We consider animals whose feeding rate depends on the size of structures that grow only by moulting (e.g. spiders' legs). Our Investment Principle predicts optimum size increases at each moult; under simplifying assumptions these are a function of the scaling of feeding rate with size, the efficiency of moulting and the optimum size increase at the preceding moult. We show how to test this quantitatively, and make the qualitative prediction that size increases and instar durations change monotonically through development. Thus, this version of the model does not predict that proportional size increases necessarily remain constant, which is the pattern described by Dyar's Rule. A literature survey shows that in nature size increases tend to decline and instar durations to increase, but exceptions to monotonicity occur frequently: we consider how relaxing certain assumptions of the model could explain this. Having specified various functions relating fitness to adult size and time of emergence, we calculate (using dynamic programming) the effect of manipulating food availability, time of hatching and size of the initial (or some intermediate) instar. The associated norms of reaction depend on the fitness function and differ from those when growth follows Dyar's Rule or is continuous. We go on to consider optimization of the number of instars. The Investment Principle then predicts upper and lower limits to observed size increases and explains why increases usually change little or decline through development. This is thus a new adaptive explanation for Dyar's Rule and for the most common deviation from the Rule.

Journal ArticleDOI
H. Visarius1, J. Gong1, Carsten Scheer1, S. Haralamb1, Lutz-Peter Nolte1 
TL;DR: The clinical potential of computer assisted surgery has been more and more widely acknowledged since CAS systems have been introduced into the operating room (OR) theater, and the improvements in safety and accuracy are remarkable and strengthen the ties between surgeons and engineers.
Abstract: The clinical potential of computer assisted surgery (CAS) has been more and more widely acknowledged since CAS systems have been introduced into the operating room (OR) theater. Especially the improvements in safety and accuracy are remarkable and strengthen the ties between surgeons and engineers. Tumor stereotaxis was introduced to neurological surgery in the early 1980s, and currently systems with and without robotic navigation are in use for specific medical indications. Recently, solutions for computer assisted orthopedic surgery were developed and applied to various anatomical regions. However, with the establishment of CAS in vivo, a new complex of problems, which was not present in the laboratory setup, was introduced: the man-machine interface. Currently, the complexity of available CAS systems requires the presence of at least one system engineer (often called the "operator") in the OR. As a consequence, there is no possibility for direct communication between the surgeon and the machine or software. Most of the program steps involved in CAS and choices to be made intraoperatively have to be transferred to the software by means of communication of the surgeon with the operator. Particularly, the establishment of a relation between the virtual object (i.e., a medical image) and the surgical object (i.e., the patient), often denoted as "matching" or "skeletal registration," requires intensive interaction of the surgeon with the computer. A literature survey revealed that no CAS system in clinical use exists without a system engineer or a comparable person, and our clinical experience indicated that the matching process is a weak point in most systems. Because it appears to be contradictory to cost-reduction efforts in health care to have a highly paid specialist in the OR, this research evaluates strategies to facilitate the man-machine interface with the final goal of establishing a direct control of the system by the surgeon or the medical personnel traditionally present at surgery. Options to be investigated include 1) a CAS control panel (virtual keyboard) as an integrated component of the existing navigation system and 2) introduction of a commercial voice-recognition system. The implementation of these strategies into the existing CAS setup at the Department of Orthopaedic Surgery at the Inselspital (University of Bern) and clinical experience gained are reported.

Journal ArticleDOI
TL;DR: A revised procedure and method for obtaining the subjective delay time estimate is proposed, and the models for combining experts' opinions and updating the delay time distribution are also discussed.

Journal ArticleDOI
TL;DR: There is some evidence of difficulty in understanding the aims and methods of RCTs, and some disquiet about elements of the RCT methodologies, which most likely reflects an absence of research rather than absence of objections.
Abstract: BACKGROUND Health technology assesment (HTA) requires scientifically rigorous experimentation involving patients as subjects. HTA itself is required so that treatment given to patients will be both effective and efficient; this requirement is itself ethical in nature. At the same time it is essential that the methods used in HTA are ethically sound. Most healthcare researchers agree that the most effective and soundest method for assessing treatments is the randomised controlled trial (RCT). However, some researchers believe that the RCT is unethical, either in essence, or for use in some forms of medical research and HTA. Furthermore, many patients seem unable to understand the principles and purposes of the RCT, a factor which is highly detrimental for the validity of informed consent. Informed consent is the key to the ethics of medical research, both in most theories and in all codes of research conduct. Many RCTs therefore risk being unethical in practice, even if ethical in principle. AIM OF REPORT To survey the main objections to the RCT and its alternatives. To assess the philosophical and methodological basis of these objections, and of the methods recommended for addressing them. To identify areas where objections are founded in social or cultural factors normally overlooked in ethical argument about the RCT methodology. To identify alternative arguments or methods which might resolve ethical conflicts in this area. HOW THE RESEARCH WAS CONDUCTED The methods used were adapted from systematic reviews in medicine. Systematic searches of Medline, Psychlit and Sociofile CD-ROM databases; hand-searches of the major journals in general medicine and surgery, medical ethics and philosophy; and searches of books were carried out. The literature survey was restricted to articles published or abstracted in English. A database of the most relevant and useful materials was compiled, and is accessible on the Internet (http://www.liv.ac.uk/sdthomps/page1.html). RESEARCH FINDINGS UNDERSTANDING RCTS AND THEIR ALTERNATIVES: There is some evidence of difficulty in understanding the aims and methods of RCTs, and some disquiet about elements of the RCT methodologies. These objections are well known and much discussed, and concern the use of placebo, the continuation of trials after significant differentials in benefit or harm are apparent, and randomisation. CULTURAL OR RELIGIOUS OBJECTIONS There was an absence of evidence of cultural or religious objections to randomisation, placebo or other kinds of controlled prospective trials. This most likely reflects an absence of research rather than absence of objections. (ABSTRACT TRUNCATED)

01 Jan 1997
TL;DR: In this article, the authors investigated the relationship between permanent deformation in unbound granular materials and the number of load cycles and the impact of applied stresses in road pavement design.
Abstract: The purpose of the study is to increase the understanding of plastic behaviour of unbound granular materials through a literature survey and laboratory testing. Reviews of previous research show that permanent deformation in granular materials is influenced by several factors. Generally, modelling of plastic behaviour is based on the gradual accumulation of permanent strain with number of load cycles and the impact of applied stresses. During the last two decades, attention has been paid to the shakedown theory and its potential for developing true analytical models in road pavement design. The experimental part of the investigation deals with the permanent deformation behaviour of five different aggregates under repetitive loading. Triaxial and hollow cylinder tests are used to assess the relationship between permanent strain and both number of load applications and stress level. The test results are used to verify some of the existing models found in the literature, with greater emphasis on the newly developed Paute model. The general concept suggested by the Paute model regarding the effect of stresses is discussed and shown to be questionable, as it leads to incorrect conclusions about material behaviour. However, the Paute model is found generally suitable for predicting the accumulation of permanent strain with number of load applications. A model is introduced expressing the accumulation of permanent axial strain, at any given number of cycles, as a function of applied stresses, taking into account the maximum shear stress ratio and the length of stress path in p-q space. The results of the analysis indicate similarities between the model and the concept of the shakedown theory. At low levels of shear stress ratio, the growth of permanent strain appears to level off, resulting in an ultimate equilibrium condition characterised by an elastic material behaviour. (A)

Patent
06 Jun 1997
TL;DR: In this article, a method of assisting the carrying out of a research process is implemented with the aid of specialized computer software, where a sequence of predetermined research process steps is defined, and prompts are generated to guide the researcher to enter proposal data and selected data is retrieved from the database to include in a written proposal to a sponsor.
Abstract: A method of assisting the carrying out of a research process is implemented with the aid of specialized computer software. The software defines a sequence of predetermined research process steps. In a first step, predetermined prompts are generated which guide the researcher to enter data corresponding to the results of a literature survey, to set up a database which is used by subsequent steps. In a second step, prompts are generated to guide the researcher to enter proposal data, and selected data is retrieved from the database to include in a written proposal to a sponsor. The proposal data and the selected reference data from the first database are combined in a second database, which is used as the basis for the next step in the process. In the next step, the software generates prompts to assist the researcher in entering research results which are also stored in the second database in a predetermined format. The contents of the altered second database are then used to generate a research report in a partially predetermined format, as well as articles or papers, and presentations. The invention streamlines the research process and is particularly advantageous in assisting inexperienced researchers to follow the corrected procedure.

Journal ArticleDOI
TL;DR: This literature survey gives a critical review of research in automation of colonoscopy through in vitro and in vivo experimentations to prove the possibilities of a robot moving along a patient's colon, treating polyps as they are encountered.
Abstract: Automation of colonoscopy can be broken down into two aspects: locomotion and steerable distal end. The problems of locomotion are concerned with activation systems and the control sequencing of actuator elements within an environment that is slippery and has a highly varied anatomy. Steerable tips have difficulties associated with the need for remote activation and the need to negotiate tight radii without penetrating the colon wall. This literature survey gives a critical review of research in these areas. The results of some of the researchers seem very promising. In vitro and in vivo experimentations have been carried out to prove the possibilities of a robot moving along a patient's colon, treating polyps as they are encountered. The authors believe that conventional colonoscopy will shortly be revolutionized.

Journal ArticleDOI
TL;DR: A comprehensive review of emerging technologies and recent developments in air pollution control equipment and processes specifically addressing particulate removal is provided in this paper, focusing on approaches with a high degree of novelty and/or involving new modifications to conventional systems.

Journal ArticleDOI
TL;DR: The first phase of a project to develop a national consensus standard for the design, fabrication, and erection of structures constructed from pultruded fiber-reinforced-plastic structural plate, rod, and shapes is described in this paper.
Abstract: This paper presents the results of the first phase of a project to develop a national consensus standard for the design, fabrication, and erection of structures constructed from pultruded fiber-reinforced-plastic structural plate, rod, and shapes. The project was undertaken by ASCE for the Pultrusion Industry Council of the Society of the Plastics Industry, Inc. The scope of Phase 1 comprises a literature survey to assemble background information for the effort, and the development of a draft outline of the standard (i.e., a “prestandard”). The effort and significant findings are discussed in this paper. It presents the proposed prestandard outline, which is annotated to include the scope of each chapter and a brief commentary on anticipated provisions. The load and resistance factor design (LRFD) philosophy, which is the basis of the prestandard, is also discussed. Design criteria, engineering properties and factors, and ancillary standards that are needed in order to implement design via the proposed ap...

01 Jan 1997
TL;DR: The longer the life-span of the host, the higher the proportion of trematode-mollusc associations where the gonad is the main site of infection, and it is found that the longer the lives of the hosts are short, the more likely it is that the parasites adjust their cercarial production to the same period as the uninfected clams.
Abstract: In a long-lived molluscan host, trematode adaptations that minimize the risk of parasite-induced host mortality may evolve because the residual reproductive value of a parasite would not be limited by a short life-span of the host. Two features of the host exploitation (site selection and timing of the reproductive period) were examined for the bucephalid trematodes Rhipidocotyle fennica and R. campanula in their first intermediate host Anodonta piscinalis which is a long-lived freshwater clam. The gonad, assumed to be less critical for survival of the host, was the organ most frequently parasitized by both of the parasite species. Except for the kidney in the case of R. campanula, the prevalence of infection was low in organs that were expected to be important for host survival (kidney, gills, digestive gland). We also made a literature survey on the site selection of larval trematodes of aquatic molluscs in general. We found that the longer the life-span of the host, the higher the proportion of trematode-mollusc associations where the gonad is the main site of infection. Infected A. piscinalis do not reproduce due to parasitic castration but the uninfected individuals develop their offspring, presumably, during the period of most abundant resources in the seasonally fluctuating environment. Therefore, if the parasites adjust their cercarial production to the same period as the uninfected clams they should minimize mortality caused by an energetic stress for the host. We found the reproductive period of R. fennica to co-occur with that of the host, while the cercarial production of R. campanula started 2 weeks earlier than the host reproduction. In summary, R. fennica followed a “damage avoidance tactic” but R. campanula to a lesser extent.