Showing papers by "University of Greenwich published in 1999"
TL;DR: In this paper, the authors extend the standard network centrality measures of degree, closeness and betweenness to apply to groups and classes as well as individuals, and propose a measure of group centrality efficiency, which indicates the extent to which a group's centrality is principally due to a small subset of its members.
Abstract: This paper extends the standard network centrality measures of degree, closeness and betweenness to apply to groups and classes as well as individuals. The group centrality measures will enable researchers to answer such questions as ‘how central is the engineering department in the informal influence network of this company?’ or ‘among middle managers in a given organization, which are more central, the men or the women?’ With these measures we can also solve the inverse problem: given the network of ties among organization members, how can we form a team that is maximally central? The measures are illustrated using two classic network data sets. We also formalize a measure of group centrality efficiency, which indicates the extent to which a group's centrality is principally due to a small subset of its members.
592 citations
TL;DR: The results support the hypothesis that bumble bees do not necessarily forage close to their nest, and illustrate that studies on a landscape scale are required if the authors are to evaluate bee foraging ranges fully with respect to resource availability.
Abstract: Summary
1. Bumble bees play a vital role in the pollination of many crops and wild flowers, and plans for their conservation require a knowledge of the dynamics and spatial scale of their foraging flights, which are, at present, poorly understood.
2. We investigated the foraging range and constancy of two colonies of bumble bees Bombus terrestris L. on a mixed arable farm using harmonic radar, which has a unique capability to record the trajectories of insects flying at low altitude in the field.
3. Foraging bees were fitted with lightweight radar transponders and tracked as they flew to and from the nest to forage. The resulting tracks gave information on length, direction and straightness of foraging routes. Superimposition onto a map of the foraging landscape allowed interpretation of the bees’ destinations in relation to the spatial distribution of forage.
4. Outward tracks had a mean length of 275·3 ± 18·5 m (n = 65) and a range of 70–631 m, and were often to forage destinations beyond the nearest available forage. Most bees were constant to compass bearing and destination over successive trips, although one bee was tracked apparently switching between forage patches. Both outward and return tracks had a mean straightness ratio of 0·93 ± 0·01 (n = 99). The bees’ ground speeds ranged from 3·0 m s–1 to 15·7 m s–1 (n = 100) in a variety of wind conditions.
5. The results support the hypothesis that bumble bees do not necessarily forage close to their nest, and illustrate that studies on a landscape scale are required if we are to evaluate bee foraging ranges fully with respect to resource availability. Such evaluations are required to underpin assessments of gene flow in bee-pollinated crops and wild flowers. They are also required when making decisions about the management of bees as pollinators and the conservation of bee and plant biodiversity.
491 citations
TL;DR: A review of evacuation models can be found in this article, where the authors describe each of the modelling approaches adopted and critically review the inherent capabilities of each approach based on available published literature.
383 citations
TL;DR: This work investigates an extension to the classical insertion-based heuristic for the vehicle routing problem with backhauling (VRPB) based on the idea of inserting more than one backhaul at a time, with encouraging results.
Abstract: We investigate an extension to the classical insertion-based heuristic for the vehicle routing problem with backhauling (VRPB). It is based on the idea of inserting more than one backhaul at a time. This method is tested on data sets with single and multiple depots with encouraging results at no additional computational burden. This approach can also be useful in generating good starting solutions for the more computer-intensive meta-heuristics.
304 citations
TL;DR: In this article, an implicit finite difference approach to the pricing of American options on assets with stochastic volatility is described and a multigrid procedure is described for the fast iterative solution of the discrete linear complementarity problems that result.
Abstract: The paper describes an implicit finite difference approach to the pricing of American options on assets with a stochastic volatility. A multigrid procedure is described for the fast iterative solution of the discrete linear complementarity problems that result. The accuracy and performance of this approach is improved considerably by a strike-price related analytic transformation of asset prices and adaptive time-stepping.
225 citations
TL;DR: In this article, the preparation of spherical phosphor particles that are monosized for a given set of conditions is described, and the nature of the resulting self-assembled and close packed phosphor spherical particles appears to be very promising for both field emission devices (FED) and high definition television (HDTV).
Abstract: The preparation of spherical phosphor particles that are monosized for a given set of conditions, are described. The nature of the resulting self‐assembled and close packed phosphor spherical particles appears to be very promising for both field emission devices (FED) and high definition television (HDTV). The size of the particles can be controlled by careful manipulation of the experimental conditions, the rationale behind this is discussed. The luminescent efficiency of the particles as a function of particle size is also reported. It is demonstrated that good light output is possible from nanocrystals. © 1999 The Electrochemical Society. All rights reserved.
179 citations
TL;DR: Hambrey, MJ; Bennett, MR; Dowdeswell, JA, et al. as mentioned in this paper studied the deformation and transfer of polythermal valley glaciers, and found that deformation entrainment and transfer occurs in the same season.
Abstract: Hambrey, MJ; Bennett, MR; Dowdeswell, JA, et al. (1999). Debris entrainment and transfer in polythermal valley glaciers. Journal of Glaciology, 45 (149), 69-86. Published: 1999
163 citations
TL;DR: In contrast with existing work that explores ethical trade issues in terms of sectors and often tries to separate social and environmental dimensions, the authors identifies the common ground between sectoral approaches, examining, for instance, work from forestry, fairtrade, agriculture and the apparel industry.
Abstract: Ethical trade is a fast-growing field both in terms of interest and practice, but one where there is little independent analysis or literature. This paper provides an overview of what is happening in the field, including the unpublished debates of many of ethical trade's key players. In contrast with existing work that explores ethical trade issues in terms of sectors and often tries to separate social and environmental dimensions, the paper identifies the common ground between sectoral approaches, examining, for instance, work from forestry, fairtrade, agriculture and the apparel industry. It shows the different approaches that are being adopted, and the strengths and weaknesses of these approaches. It also highlights the consequences for developing countries of initiatives that are typically driven by the North, and how existing approaches do not lend themselves to participation by Southern stakeholders. The paper concludes by arguing the need for greater integration of social and environmental issues, ...
151 citations
TL;DR: A review of evacuation models can be found in this paper, where the authors describe each of the modelling approaches adopted and critically review the inherent capabilities of each approach based on available published literature.
Abstract: Computer based analysis of evacuation can be performed using one of three different approaches, namely optimization, simulation and risk assessment. Furthermore, within each approach different means of representing the enclosure, the population and the behaviour of the population are possible. The myriad of approaches that are available has led to the development of some 22 different evacuation models. This review attempts to describe each of the modelling approaches adopted and critically review the inherent capabilities of each approach. The review is based on available published literature.
146 citations
TL;DR: These studies indicate that feeding quebracho tannin to ruminants has both ruminal and post-ruminal effects that, together, result in reduced nutrient utilisation and impaired animal performance.
Abstract: The effect of feeding quebracho tannin, a mixture of condensed tannins, on dietary nutrient utilisation and nitrogen (N) retention and its effects on the gastrointestinal (GI) tract was investigated in sheep and rats. Sheep (n = 24) were fed on a pelleted diet of dried grass alone (controls) or containing quebracho tannin at 50 g kg−1 diet dry matter (DM) (tannin-fed animals) at a level sufficient to achieve a daily liveweight gain (DLWG) of 100 g day−1. Complete collections of faeces and urine were made for two seven-day periods after two and six weeks of feeding these diets (n = 6 per group). Apparent digestibilities of dry matter, N and neutral detergent fibre (NDF) were significantly (P < 0.001) reduced in tannin-fed animals at both measurement periods. No evidence was obtained to suggest that rumen micro-organisms can adapt to the presence of dietary tannins with prolonged feeding. Tannin-fed animals excreted significantly (P < 0.01) more N in faeces and less in urine than controls suggesting an alteration in N metabolism. Histological examination of samples of the GI tract obtained from pairs of sheep slaughtered after two, five and seven weeks of feeding the diets indicated ulceration and an increase in mucosal histiocytes, particularly in the jejunum and ileum of most tannin-fed animals. In a subsequent experiment, rats were fed ad libitum a ground chow containing either cellulose or quebracho tannin at 40 g kg−1 DM. Tannin-fed rats had significantly (P < 0.05) reduced feed intakes, DLWG, N retention and body fat deposition compared to controls. Protein synthesis rates in the duodenal mucosa were not increased in tannin-fed rats suggesting that enterocyte proliferation was not stimulated in this region of the GI tract.
These studies indicate that feeding quebracho tannin to ruminants has both ruminal and post-ruminal effects that, together, result in reduced nutrient utilisation and impaired animal performance.
© 1999 Society of Chemical Industry
133 citations
TL;DR: Chemostratigraphy has been applied to onshore Duckmantian/Stephanian successions encountered in outcrop and penetrated by two boreholes from the West Midlands (U.K.).
TL;DR: In this article, the Apsheron sill is defined as a south-dipping basin characterized by fault-controlled facies and thickness variations, and the large-scale east-west- to west-northwest-east-southeast oriented arrays of periclinal folds of the Kopet Dag range, which indicate a north-south oriented compression, were generated by a fault propagation mechanism.
Abstract: The 2-17-km-thick, post-Triassic sediments of the Turan continental block accumulated in a south-dipping basin characterized by fault-controlled facies and thickness variations. Since the late Miocene, the thickest part of the basin fill, on the southern margin of the Turan block, has been folded and uplifted as the Kopet Dag range, in response to the Iran-Turan convergence. The Apsheron sill, which separates the northern continental from the southern oceanic Caspian Sea basins, links the Kopet Dag-Greater Balkan ranges (Turkmenistan) to the Caucasus (Azerbaijan). The large-scale east-west- to west-northwest-east-southeast-oriented arrays of periclinal folds of the Kopet Dag range, which indicate a north-south oriented compression, were generated by a fault propagation mechanism. The migration and accumulation of hydrocarbons has been controlled by the deformation pattern. The 75 km of north-south shortening in the western Kopet Dag-Greater Balkan area can be resolved into 70 km of pure compression, orthogonal to the N120°-oriented Ashgabat fault, and 35 km of dextral slip along this fault. The north-south Iran-Asia relative motion has produced the oblique convergent northwest-southeast structures along the dextral Ashgabat fault and the pure convergent east-west structures in the western Kopet Dag-Greater Balkan region. The orientation of the structures has been controlled by the angular relationship between the relative motion of two blocks and the orientation of their boundaries. The Ashgabat fault as a major crustal anisotropy has concentrated the deformation into a narrow fold and thrust belt, whereas in the west the deformation is distributed over a wider area. The pattern of deformation has been controlled by the Iran-Turan boundary conditions.
TL;DR: In this article, it was shown that clast fabric alone alone is not able to discriminate between different glacigenic facies, and it is argued that it offers little quantitative support in the interpretation of glacigenics sediments.
Abstract: The interpretation of glacigenic diamictons is a subjective process, for which quantitative support is frequently sought from parameters such as clast shape and fabric. It has been widely suggested that different glacigenic diamicton facies possess distinct clast-fabric signatures. This paper examines this concept using a data set of 111 clast fabrics, and a synthesis of published results. Eigenvalues are calculated and compared for a variety sedimentary facies. It is concluded that clast fabric alone is not able to discriminate between different glacigenic facies, and it is argued that clast fabric offers little quantitative support in the interpretation of glacigenic sediments. It is suggested, therefore, that although clast fabric may continue to have a role as an indicator of relative strain at specific sites, its use in the discrimination of glacigenic facies is limited. Consequently, we should be much more selective in undertaking such analyses in the future. Copyright © 1999 John Wiley & Sons, Ltd.
TL;DR: In this paper, Church et al. explored the significance of cross-border strategies for the development and restructuring of the role of local governance in institutional arrangements and territories, and considered the interaction between crossborder spaces, the transnational spatial planning regions promoted by the European Commission and the emerging regional politics of South East England.
Abstract: CHURCH A. and REID P. (1999) Cross-border co-operation, institutionalization and political space across the English Channel, Reg. Studies 33 , 643-655. Cross-border initiatives are based on flexible co-operative networks and have many of the characteristics which the institutionalist perspective argues are often present in regions that have developed effective institutional forms. Transfrontier programmes involving local authorities in northern France and southern England are examined. The paper explores the significance of cross-border strategies for the development and restructuring of the role of local governance in institutional arrangements and territories. It also considers the interaction between cross-border spaces, the transnational spatial planning regions promoted by the European Commission and the emerging regional politics of South East England. CHURCH A. and REID P. (1999) La cooperation transfrontaliere, l'institutionnalisation et l'espace politique outre Manche, Reg. Studies 33 , 643-655. ...
TL;DR: Nucleotide and derived amino acid sequences of the 13 protein-coding genes from Atlantic salmon have been compared with their counterparts in rainbow trout and a putative structure for the origin of L-strand replication is proposed.
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01 Feb 1999TL;DR: Three parallel optimisation algorithms, for use in the context of multilevel graph partitioning of unstructured meshes, are described and are compared and seen to produce very high global quality partitions, very rapidly.
Abstract: Three parallel optimisation algorithms, for use in the context of multilevel graph partitioning of unstructured meshes, are described. The first, interface optimisation, reduces the computation to a set of independent optimisation problems in interface regions. The next, alternating optimisation, is a restriction of this technique in which mesh entities are only allowed to migrate between subdomains in one direction. The third treats the gain as a potential field and uses the concept of relative gain for selecting appropriate vertices to migrate. The results are compared and seen to produce very high global quality partitions, very rapidly. The results are also compared with another partitioning tool and shown to be of higher quality although taking longer to compute.
TL;DR: In this paper, a system consisting of a high-speed CCD camera, a frame grabber and associated image processing software was developed for on-line continuous flicker measurements of combustion flames.
Abstract: The flicker of a flame is an important physical parameter associated with the characteristics of a combustion process. This paper presents a novel instrumentation system developed for on-line continuous flicker measurements of combustion flames. The system comprises a high-speed CCD camera, a frame grabber and associated image processing software. The flicker signal was obtained by processing the radiation intensity of individual pixels within the luminous region of a flame image. Power spectral density analysis was performed to obtain the frequency components of the flicker signal. The quantitative flicker of a flame is defined in terms of weighted spectral components in the frequency domain and this definition has been proven to be well suited to quantification of the flickering characteristics of a flame. A tungsten lamp driven by a frequency-varying power supply was employed to calibrate the measurement system. The calibration results show that the system is capable of measung the flicker of an unknown light source with a relative error no greater than 3% . The system developed has been utilized to investigate the relationship between the flicker of a diffusion flame and the burner diameter, and to study the effect of the equivalence ratio on the flicker of a premixed flame under a range of combustion conditions. The experimental results obtained by both motion image analysis and spectral analysis have demonstrated that the flicker of a diffusion flame depends predominantly on the burner diameter. It has also been found that the flicker of a premixed flame varies with the equivalence ratio and a peak flicker exists for a given air flow rate.
TL;DR: In this article, the authors combined these factors with measures from Bandura's self efficacy theory (computer self efficacy and computer anxiety) in conjunction with assessments of current computer experience to account for how perceived ease of use, perceived usefulness, and attitudes predict behavioral intention to use computers and found that self-reported wordprocessor usage over a 13-week period was predicted by levels of usage at the beginning of the semester, expected usage, and perceived usefulness.
TL;DR: In this paper, the flight trajectories of individual bumble-bees (Bombus terrestris L) foraging over arable farmland were used to study the effect of lateral wind drift on honeybee navigation and found that most bees overcompensated by heading partly into the wind and moving obliquely over the ground.
Abstract: In his classic studies on honeybee navigation, von Frisch had to rely on qualitative visual observations of the bees' flight paths, but nevertheless reached the surprising conclusion that bees seem to anticipate lateral wind drift and compensate by flying in shallow curves on the upwind side of their intended tracks1,2. We have investigated wind compensation1,2,3 with much greater precision by using radar4,5 to record the flight trajectories of individual bumble-bees (Bombus terrestris L.) foraging over arable farmland6. Flights typically covered distances of 200 to 700 metres, but bees maintained direct routes between the forage areas and their nests, even in winds with a strong cross-track component. Some bees overcompensated slightly, as described by von Frisch, but most stayed on course byheading partly into the wind and moving obliquely over the ground.
09 Aug 1999-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: The anatomy and optics of the eyes of a range of mosquito species from the wholly dark-active blood-feeding Anopheles gambiae to the diurnal plant-feeder Toxorhynchites brevipalpis are studied, finding that dark- active and crepuscular species have short fused rhabdoms with a conical construction.
Abstract: We have studied the anatomy and optics of the eyes of a range of mosquito species from the wholly dark-active blood-feeding Anopheles gambiae to the diurnal plant-feeder Toxorhynchites brevipalpis. Consistent with studies by Sato in the 1950s, we find that dark-active and crepuscular species have short fused rhabdoms with a conical construction. This maximises the amount of light the rhabdoms receive from the almost hemispherical wide-aperture lenses. Toxorhynchites, on the other hand, has long narrow rhabdomeres that are separated from each other over their entire length, and so resemble the open rhabdoms of advanced flies (Brachycera and Cyclorrhapha). These findings are confirmed by studies of the pseudopupil, whose form indicates the layout of the rhabdomere tips in the focal plane of each ommatidial lens. In anopheline species the pseudopupil is a single undivided ellipse, indicating a fused rhabdom structure, whereas in Toxorhynchites there is a ring of six outer elements surrounding a central one. This means that each rhabdomere views a separate direction in space, and our measurements indicate that, as in higher Diptera, adjacent rhabdomeres share their fields of view with one of the rhabdomeres in the immediately adjacent ommatidia. This in turn means that in the diurnal type of mosquito eye there is a basis for neural superposition, but the fused construction of anopheline rhabdoms precludes this. The Aedes species studied were similar to Anopheles but with lenses of less extreme aperture, and Sabethes cyaneus, a diurnal blood-feeder, was intermediate in structure, with fused conical rhabdoms in the centre of the eye and unfused rhabdomeres around the periphery.
TL;DR: The composition of two varieties of Omani dates, fard and khalas, was determined as maturity progressed as mentioned in this paper, and free sugars and dietary fibre content were examined in detail.
Abstract: The composition of two varieties of Omani dates, fard and khalas, was determined as maturity progressed. Free sugars and dietary fibre content were examined in detail. High-performance liquid chromatography (HPLC) of the extracts showed that at the early green stage (Arabic kimri), dates contained small amounts of glucose and fructose. At the intermediate yellow (khalal) and red (rutab) stages, large amounts (500–565 g kg−1 dry weight) of sucrose had accumulated, but no additional glucose or fructose was detected. At the final mature (tamar) stage, all sucrose was converted to glucose and fructose (>800 g kg−1 dry weight). Dietary fibre, determined as non-starch polysaccharides (NSPs) by gas chromatography (GC), decreased from 250 g kg−1 (kimri) to 50 g kg−1 (tamar) on a dry weight basis. The principal monomers of NSPs were glucose, galactose, xylose, mannose, arabinose and rhamnose. On a dry weight basis, pectin, protein and ash contents decreased as the dates matured. On a fresh weight basis, changes in NSPs, pectin, protein and ash could be attributed to loss of moisture and the accumulation of sucrose initially, or of invert sugar later as maturation progressed.
© 1999 Society of Chemical Industry
TL;DR: Radial basis function (RBF) neural network models for the simultaneous estimation of flash point (Tf) and boiling Point (Tb) based on 25 molecular functional groups and their first-order molecular connectivity index (1χ) have been developed.
Abstract: Radial basis function (RBF) neural network models for the simultaneous estimation of flash point (Tf) and boiling point (Tb) based on 25 molecular functional groups and their first-order molecular connectivity index (1χ) have been developed. The success of the whole modeling process depended on a network optimization strategy based on biharmonic spline interpolation for the selection of an optimum number of RBF neurons (n) in the hidden layer and their associated spread parameter (σ). The RBF networks were trained by the Orthogonal Least Squares (OLS) learning algorithm. After dividing the total database of 400 compounds into training (134), validation (133), and testing (133), the average absolute errors obtained for the validation and testing sets ranges from 10 °C to 12 °C and 11 °C to14 °C for Tf and Tb, respectively, and are in agreement with the experimental value of about 10 °C. Results of a standard Partial Least Square (PLS) regression model for single output predictions range from 23 °C to 24 °C...
TL;DR: In this article, the authors describe the landform and sediment assemblage produced by a surge (in 1948) of the Kongsvegen/Kronebreen glacier complex in northwest Spitsbergen.
TL;DR: The results show that pregnancy-related weight gains are not simply the result of retaining weight that is gained during pregnancy, but that they also originate from gaining additional weight in the postpartum period.
Abstract: The aim of the present study was to assess whether the psychosocial and behavioral changes that occur during and after pregnancy influence long-term weight gain. The study examined 74 mothers enrolled in the Antenatal Care (ANC) Project (a randomized controlled trial of antenatal care based in South London), all of whom had volunteered to take part in a subsequent follow-up study. Data on body weight at the beginning of pregnancy; lifestyle and behavior during pregnancy; antenatal care and obstetric history; together with measures of postnatal depression and parenting stress following pregnancy were taken from the existing ANC Project database. Additional measurements of height and weight together with information on a variety of lifestyle changes and psychosocial characteristics, were gathered during semi-structured interviews at each mother's home, two and a half years after their children had been born. The results show that pregnancy-related weight gains are not simply the result of retaining weight that is gained during pregnancy, but that they also originate from gaining additional weight in the postpartum period. Mothers who felt they ate more after their children were born, had significantly greater long-term weight gains (2.78 (1.42) kg) than those who felt that they had not increased their food intake (-1.15 (0.76) kg; t = 2.49, p = 0.016). Similarly, mothers who felt they had greater access to food postpartum, had significantly greater long-term weight gains (1.70 (0.87) kg) than those who felt they did not have greater access to food (-1.37 (1.13) kg; t = 2.18, p = 0.032). There was some evidence that the lifestyle changes which accompany pregnancy and motherhood increase some women's vulnerability to eating disorder psychopathology. Mothers who felt they did less exercise after pregnancy than they did before, were also at greater risk of long-term weight gain (p = 0.028), as were mothers with low numbers of supportive individuals (p = 0.033). Neither the stress of parenting nor maternal depression were significantly associated with an increased risk of long-term weight gain (p > 0.05).
TL;DR: Beauveria bassiana isolates possessing the capacity to grow systemically in the maize plant are considered one of the more interesting candidates for development as microbial control agents despite limited control in preliminary trials.
Abstract: A review of the existing basis for maize stem borer IPM is given and the role of pathogens in the system is evaluated. Survey work outlining the major groups of insect pathogens is described; fungi (Beauveria bassiana and Metarhizium anisopliae), bacteria (Bacillus thuringiensis and Serratia marcesens), and viruses (granuloviruses and cytoplasmic polyhedroviruses) were identified. The presence of other unidentified protozoans, nematodes, fungi and viruses was noted. The virulence of some of the more promising known insect pathogens was explored in preliminary bioassays. Considering the cryptic habits of the insects, and the low input agriculture practiced by the majority of maize farmers in sub-Saharan Africa, Beauveria bassiana isolates possessing the capacity to grow systemically in the maize plant are considered one of the more interesting candidates for development as microbial control agents despite limited control in preliminary trials. Further work should also investigate the potential of pathogens of moderate virulence, such as the protozoans and CPVs.
TL;DR: It was clear that varietal resistance to infection could be an important component of disease management but whether, once infected, the tomato plants acted as a source of inoculum had little impact on disease incidence in the tomato crop.
Abstract: Summary
1. A number of insect vectors of plant-virus diseases make only transitory visits to the crop in which the economic effects of the disease are important. The incidence of disease in the crop depends primarily on the immigration of vectors from alternative hosts which act as a reservoir of both the virus and vector.
2. An epidemiological model was developed to represent this situation and parameters were estimated for the case of tomato leaf curl virus disease (TLCVD) (Geminiviridae, Subgroup III) in India. From an analysis of the model, the following possibilities for the management of TLCVD emerged.
3. It was clear that varietal resistance to infection could be an important component of disease management but whether, once infected, the tomato plants acted as a source of inoculum had little impact on disease incidence in the tomato crop.
4. A very low rate of simulated vector immigration into a tomato crop sufficed to cause almost total infection. Around Bangalore, vectors may migrate into tomato crops in numbers in excess of those required for disease ‘saturation’, explaining why, using conventional insecticides, very efficient and intensive vector control is currently required to reduce disease incidence.
5. Disease incidence was sensitive to vector mortality only when vector numbers were low. In most cases, the immigration of viruliferous vectors made disease incidence insensitive to the mortality of vectors within the tomato crop.
6. A strategy for disease management which targets more than one of the parameters to which the model proved most sensitive is likely to be necessary. In particular, the use of protective netting combined with the growing of resistant varieties has the potential to reduce both B. tabaci immigration to the crop and to reduce virus inoculation by those insects which do reach the crop.
15 Jul 1999-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: Comparison of age modelled, unfiltered grey–scale data between the two sections reveals strikingly similar patterns, and enables the identification of a 80 ka hiatus in the UK chalks.
Abstract: Outcrops of Cenomanian marly chalks in the Crimea (Ukraine) and SE England (UK), 2600 km apart, display conspicuous decimetrescale rhythmicity and can be correlated by using 12 biostratigraphical events. Closely spaced samples from the two sections were used to generate long timeseries of digitally captured greyscale reflectance data. Spectral analysis of these data demonstrates that if the rhythmicity is assumed to be driven by precession (bedding cycles; mode at 20 ka), it is seen to be modulated by the short eccentricity cycle (100 ka bundles). The latter signal is expressed in the sediments by the occurrence of dark marls at precession minima occurring at eccentricity maxima. Although identified in the spectra, tilt (38 ka) and the long eccentricity cycle (400 ka) are not strongly expressed. Comparison of age modelled, unfiltered greyscale data between the two sections reveals strikingly similar patterns, and enables the identification of a 80 ka hiatus in the UK chalks.
TL;DR: In this article, the relation between phosphorus, flow and chlorophyll-a (used as the measure of algal abundance) was analyzed by regression analysis, showing that there was a clear relationship between phosphorus and phytoplankton growth.
TL;DR: The results of this study suggest that under the experimental conditions PA athletes are at no greater thermal risk than AB athletes and a relationship between the available muscle mass for heat production and sweating capacity appears evident for the maintenance of thermal balance.
Abstract: STUDY DESIGN Single trial, two factor repeated measures design. SETTING England, Cheshire. OBJECTIVES To examine the thermoregulatory responses of able-bodied (AB) athletes, paraplegic (PA) athletes and a tetraplegic (TP) athlete at rest, during prolonged upper body exercise and recovery. METHODS Exercise was performed on a Monark cycle ergometer (Ergomedic 814E) adapted for arm exercise at 60% VO2 peak for 60 min in cool conditions ('normal' laboratory temperature; 21.5+/-1.7 degrees C and 47+/-7.8% relative humidity). Aural and skin temperatures were continually monitored. RESULTS Mean (+/-S.D.) peak oxygen uptake values were greater (P<0. 05) for the AB when compared to the PA (3.45+/-0.45 l min-1 and 2. 00+/-0.46 l min-1, respectively). Peak oxygen uptake for the TP was 0.91 l min-1. At rest, aural temperature was similar between groups (36.2+/-0.3 degrees C, 36.3+/-0.3 degrees C and 36.3 degrees C for AB, PA and TP athletes, respectively). During exercise, aural temperature demonstrated relatively steady state values increasing by 0.6+/-0.4 degrees C and 0.6+/-0.3 degrees C for the AB and PA athletes, respectively. The TP athlete demonstrated a gradual rise in aural temperature throughout the exercise period of 0.9 degrees C. Thigh skin temperature increased by 1.3+/-2.5 degrees C for the AB athletes (P<0.05) whereas the PA athletes demonstrated little change in temperature (0.1+/-3.4 degrees C and -0.7 degrees C respectively). Calf temperature increased for the PA athletes by 1.0+/-3.6 degrees C (P<0.05), whereas a decrease was observed for the AB athletes of -1.0+/-2.0 degrees C (P<0.05) during the exercise period. During 30 min of passive recovery, the AB athletes demonstrated greater decreases in aural temperatures than those for the PA athletes (P<0. 05). Aural temperature for the TP increased peaking at 5 min of recovery remaining elevated until the end of the recovery period. Fluid consumption and weight losses were similar for the AB and PA athletes (598+/-433 ml and 403+/-368 ml; 0.38+/-0.39 kg and 0.38+/-0. 31 kg, respectively), whereas changes in plasma volume were greater for the AB athletes (-9.8+/-5.8% and 4.36+/-4.9%, respectively; P<0. 05). CONCLUSION The results of this study suggest that under the experimental conditions PA athletes are at no greater thermal risk than AB athletes. A relationship between the available muscle mass for heat production and sweating capacity appears evident for the maintenance of thermal balance. During recovery from exercise, decreases in aural temperature, skin temperature and heat storage were greatest for the AB athletes with the greatest capacity for heat loss and lowest for the TP athlete with the smallest capacity for heat loss. Initial observations on one TP athlete suggest substantial thermoregulatory differences when compared to AB and PA athletes.
TL;DR: The incubation period and temperature are identified as key factors, although they account for less than 40% of the yield variation, and the variation in conidial viability and contamination are correlated with several parameters, but none can adequately explain this variation.
Abstract: Aerial conidia of Metarhizium anisopliae (flavoviride) var. acridum strain IMI 330189 used for the inundative biological control of grasshoppers and locusts in sub-Saharan Africa are produced in a purpose-built facility at the International Institute for Tropical Agriculture in Benin using a standard, two-stage mass-production system. The yields average 31.1 g of dry conidia powder/kg of rice substrate, the production capacity is 300-350 kg of conidia/year and the production costs are estimated at US$21/100 g (the recommended dose for 1 ha). The production process parameters vary within narrow limits established during optimization, but the yield is characterized by a high level of variation over time. The incubation period and temperature are identified as key factors, although they account for less than 40% of the yield variation. The variation in conidial viability and contamination are correlated with several parameters, but none can adequately explain this variation. The handling time, a principal li...