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Major Influence (major + influence)
Selected AbstractsA Catastrophic Destruction of African Forests about 2,500 Years Ago Still Exerts a Major Influence on Present Vegetation FormationsIDS BULLETIN, Issue 1 2002Jean Maley First page of article [source] Major influence of liver function itself but not of immunosuppression determines glucose tolerance after living-donor liver transplantation,,LIVER TRANSPLANTATION, Issue 4 2006Martin Stockmann Controversial data exists concerning the impact of immunosuppressive therapy on the development of post-transplantation diabetes mellitus (PTDM). Therefore, we investigated glucose metabolism in healthy donors and in recipients of living-donor liver transplants (LD-LTX, n=18) without pre-existing diabetes mellitus before, on day 10, month 6, and month 12 after intervention. The computer-assisted analysis of glucose, insulin, and C-peptide profiles obtained from frequently sampled intravenous glucose tolerance tests allows to achieve an integrated view of factors controlling glucose tolerance, i.e., insulin sensitivity (SI), first and second phase insulin secretion (,1 and ,2). SI of donors declined by day 10 after operation (SI 2.65 ± 0.41 vs. 4.90 ± 0.50 10,4 minute,1 ,U ml,1, P < 0.01) but returned to values as before after 6 months. ,1 did not change. ,2, however, significantly increased by day 10 (8.57 ± 0.82 109 minute,1 to 13.77 ± 1.53 109 minute,1, P < 0.01) but was in the same range as before after 6 months. In parallel to donors SI of recipients progressively increased after LD-LTX. ,1 did not alter in recipients. ,2 continuously decreased and was not different from donors by month 12. The extent of liver injury assessed by liver enzyme concentrations and liver function represented by cholinesterase activity, albumin, and INR were closely related with changes of SI in donors and recipients during the first year after intervention. In conclusion, the extent of liver damage plays a predominant role in regulating glucose tolerance. No impact of immunosuppressive therapy on SI, ,1 and ,2 was detected. Liver Transpl 12:535,543, 2006. © 2006 AASLD. [source] Understanding the ,epidemic' of complete tooth loss among older New ZealandersGERODONTOLOGY, Issue 2 2010Philip V. Sussex doi:10.1111/j.1741-2358.2009.00306.x Understanding the ,epidemic' of complete tooth loss among older New Zealanders Objective:, The aim of this study was to obtain a deeper understanding of the social factors driving New Zealand's historic ,epidemic of edentulism' and how they operated. Method:, In-depth, semi-structured interviews with 31 older New Zealanders were analysed using applied grounded theory. Results:, Universal factors present in the data were: (a) the way in which New Zealand society accepted and indeed encouraged edentulism without stigma for those who had a ,sub-optimal' natural dentition; (b) how the predominant patterns of dental care utilisation (symptomatic and extraction-based) were often strongly influenced by economic and social disadvantage; and (c) the way in which lay and professional worldviews relating to ,calcium theory' and dental caries were fundamental in decisions relating to the transition to edentulism. Major influences were rural isolation, the importance of professional authority and how patient-initiated transitions to edentulism were ultimately facilitated by an accommodating profession. Conclusion:, The combined effects of geography, economics, the dental care system and the professional culture of the day, in the context of contemporary (flawed) understandings of oral disease, appear to have been the key drivers. These were supported (in turn) by a widespread acceptance by the profession and society alike of the extraction/denture philosophy in dealing with oral disease. [source] Particle clusters in gravel-bed rivers: an experimental morphological approach to bed material transport and stability conceptsEARTH SURFACE PROCESSES AND LANDFORMS, Issue 11 2005Lea Wittenberg Abstract Structured gravel river beds clearly exert a major influence on bed stability. Indexing structural stability by field measurements of bed strength neglects the processes operating to entrain and transport bed material in different parts of each structure. This study takes a morphological approach to interpreting the critical processes, using particle tracing to determine the movement of individual cluster particles over a range of flood event magnitudes and durations. The experiment was carried out on the River South Tyne, UK; it uses flow hydrographs measured nearby and also benefits from previous studies of historical development, channel morphology and sediment transport at the same site. More than 30 clusters were monitored over a seven-month period during which clusters occupied 7,16 per cent of the bed. Threshold flows delimiting three apparently contrasting bed sediment process regimes for cluster particles are tentatively set at 100 m3 s,1 and 183 m3 s,1; durations of flow at these levels are critical for cluster development, rather than flow peak values. Wake particles are transported most easily. Flow straightening in the wandering channel planform reduces the stability of clusters, since mechanical strength is markedly reduced by this change of direction. The overall area covered by clusters between significant transport events varies little, implying a dynamic equilibrium condition. Copyright © 2005 John Wiley & Sons, Ltd. [source] Host shifting by Operophtera brumata into novel environments leads to population differentiation in life-history traitsECOLOGICAL ENTOMOLOGY, Issue 5 2003Adam J. Vanbergen Abstract., 1. Operophtera brumata L. (Lepidoptera: Geometridae), a polyphagous herbivore usually associated with deciduous trees such as oak Quercus robur L., has expanded its host range to include the evergreen species heather Calluna vulgaris (L.) Hull and, most recently, Sitka spruce Picea sitchensis (Bong.) Carrière. 2. Phenology, morphology, and survival of O. brumata were measured at several life-history stages in populations from the three different host plant communities sampled from a range of geographical locations. The data were used to test for population differences, reflecting the marked differences in host-plant secondary chemistry, growth form, and site factors such as climate. The hypothesis that spruce-feeding populations originated from populations feeding on moorland, commonly sites of coniferous afforestation, was also tested. 3. Altitude, not host plant species, was the major influence on the timing of adult emergence. An effect of insect population independent of altitude was found, implying that additional unidentified factors contribute to this phenological variation. Larval survival and adult size varied between populations reared on different host plant species. Survival of larvae was affected negatively when reared on the novel host plant, Sitka spruce, versus the natal plant (oak or heather) but oak and heather-sourced insects did not differ in survivorship on Sitka spruce. 4. Host range extension into novel environments has resulted in population differentiation to the local climate, demonstrating that host shifts pose challenges to the herbivore population greater than those offered by the host plant alone. The hypothesis that Sitka spruce feeding populations have arisen predominantly from moorland feeding populations was not supported. [source] Estimating the probability of bird mortality from pesticide sprays on the basis of the field study recordENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2002Pierre Mineau Abstract The outcome of avian field studies was examined to model the likelihood of mortality. The data were divided into clusters reflecting the type of pesticide application and bird guilds present on site. Logistic regression was used to model the probability of a bird kill. Four independent variables were tested for their explanatory power: a variable reflecting acute oral toxicity and application rate; a variable reflecting the relative oral to dermal toxicity of the pesticides; Henry's law constant; and a variable reflecting possible avoidance of contaminated food items, the hazard factor (HF). All variables except for HF significantly improved model prediction. The relative dermal to oral toxicity, especially, was shown to have a major influence on field outcome and clearly must be incorporated into future avian risk assessments. The probability of avian mortality could be calculated from a number of current pesticide applications and the conclusion was made that avian mortality occurs regularly and frequently in agricultural fields. [source] Social Environment and Feeding State Influence Movement Decisions in a Web-building SpiderETHOLOGY, Issue 10 2009Maxence Salomon It is well recognized that feeding rate has a major influence on the amount of movement between microhabitats for many animals. However, the role of other extrinsic and intrinsic factors, and particularly how these factors may interact, is not well understood. This three-part study examines the movement decisions of a web-building spider, Latrodectus hesperus, by assessing microhabitat tenacity in established spiders and by testing how the presence of conspecific neighbours and the combined influence of individual feeding state (determined by prior feeding experience) and neighbour presence influence microhabitat residence time in unestablished spiders. The results show that naturally established spiders did not leave their microhabitats readily, emphasizing the importance of choosing a profitable location. Unestablished spiders stayed longer in microhabitats occupied by conspecifics than in unoccupied ones, and there was practically no cannibalism even though neighbours shared webs. Furthermore, feeding state and neighbour presence showed an interactive effect on microhabitat residence time. When spiders were housed alone, microhabitat residence time increased with feeding state. However, in the presence of conspecifics, spiders had a low propensity to move, regardless of feeding state. Together, these results demonstrate the combined importance of grouping dynamics and feeding state in shaping movement decisions. [source] Effects of wetting and drying cycles on in situ soil particle mobilizationEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2008S. Majdalani Summary Understanding particle mobilization and transport in soils is a major concern for environmental protection and water resource management as they can act as vectors for sorbing pollutants. In natural soils, the existence of a finite size and renewable pool of dispersible particles has been hypothesized. Even though freeze-thaw and wetting-drying cycles have been identified as possible mechanisms of pool replenishment between rainfall events, to date the underlying phenomena ruling the renewal of particle pools are still largely unexplored. We carried out a series of infiltration-drainage experiments to study systematically the effects of periods without rain (pauses) on in situ particle mobilization in undisturbed soil columns. We found that, for a given column, pause duration between two rainfall events has a major influence on subsequent particle mobilization: the mass of leached particles increases with pause duration until it reaches a maximum (mass for a 200-hours pause is 15 time greater than for a 1-hour pause), and then it decreases for even longer pauses. This behaviour was correlated with soil water content, and can be explained by soil matrix weakening due to differential capillary stresses during drying. The consequences of this finding are important because the 15-fold increase in mass of leached particles, when pause duration is changed from 1 hour to 4 days, might overwhelm variations caused by changes in other parameters such as the ionic strength of the incoming solution or the rainfall intensity. [source] SEASONAL CYCLES OF ALLOZYME-BY-CHROMOSOMAL-INVERSION GAMETIC DISEQUILIBRIUM IN DROSOPHILA SUBOBSCURAEVOLUTION, Issue 4 2003Francisco Rodríguez-Trelles Abstract Allozyme loci are frequently found non randomly associated to the chromosomal inversions in which they are included in Drosophila. Two opposite views compete to explain strong allozyme-by-inversion gametic disequilibria: they result from natural selection or, conversely, merely represent remnants of associations accidentally established at the origin of inversions. Empirical efforts aimed at deciding between adaptive and historical scenarios have focused on the spatial distribution of disequilibria. Yet, the evolutionary significance of these associations remains uncertain. I report here the results of a time-series analysis of the seasonal variation of alleles at six allozyme loci (Acph, Lap, Pept-1, Ao, Mpi, and Xdh) in connection with the O chromosomal polymorphisms of D. subobscura. The findings were: (1) in the segment I of the O chromosome, Lap and Pept-1 allozymes changed seasonally in a cyclical fashion within the ST gene arrangement, but they changed erratically within the 3+4 gene configuration; (2) the frequencies of Lap111 and Pept-10,40 within ST dropped to their lowest values in early and late summer, respectively, when the seasonal level of the ST arrangement is lowest. Furthermore, Lap1,11 and Pept-10,40 covary with ST only within these seasons, yet in a fashion inconsistent with these alleles having a major influence on the dynamics of the inversion; (3) seasonal cycling of alleles within inversions were not detected at Acph, Ao, Mpi, and Xdh, yet these loci are nearly monomorphic at the study population, and/or their sampled series were shorter than those for Lap and Pept-1; and (4) simply monitoring allozyme frequencies separately for each inversion proved to be superior, for evidencing the seasonal cycles of the disequilibria, to the use of the D' coefficient of association. Observed seasonal cycles of allozymes within inversions likely reflect natural selection. [source] Glechoma hederacea (Lamiaceae) in North America: invasion history and current distribution,FEDDES REPERTORIUM, Issue 1-2 2004M. Scholler Glechoma hederacea L. (Ground-ivy, Lamiaceae), a perennial mat-forming herb, is native to the temperate regions of Eurasia and was introduced elsewhere (South East Asia, New Zealand and North America). Based on data obtained from herbaria, literature, online and other data bases and field studies, we documented the invasion history and current distribution of this plant in North America. At present, the plant is recorded from all but two continental states of the USA and all southern provinces of Canada. There are two main ranges: the larger one covers mainly the eastern part of the U.S.A. and a smaller one stretches along the West Coast. While published records of Glechoma hederacea date from 1814, the oldest specimen is from 1829. During the 19th century the species spread westwards at a rate of approximately 30 km/year. The spread and present range of G. hederacea can only be explained by climatic factors (degree of oceanicity) and considering human activity. Especially long distance propagation of vegetative parts of the plants and the change of the environment that accompanies human settlements may have had a major influence on these processes. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) Glechoma hederacea L. (Lamiaceae) in Nordamerika: Invasionsgeschichte und derzeitige Verbreitung Glechoma hederacea (Gewöhnlicher Gundermann; Lamiaceae), eine im temperaten Eurasien beheimatete ausdauernde krautige Pflanze konnte sich als Neophyt in Südostasien, Neuseeland und Nordamerika etablieren. Basierend auf Daten aus der Literatur und Datenbanken, Belegdaten aus Herbarien und Felduntersuchungen werden die Ausbreitungsgeschichte der Art in Nordamerika und ihr gegenwärtiges Areal dokumentiert. Gegenwärtig ist die Art aus allen kanadischen Provinzen und mit Ausnahme von zwei Bundesstaaten auch von allen kontinentalen Bundesstaaten der USA dokumentiert. Es gibt zwei Hauptareale: ein großes, welches einen Großteil der östlichen USA einnimmt und ein kleineres an der Westküste. Der älteste Nachweis von 1814 von Glechoma hederacea stammt aus der Literatur, der älteste Beleg von 1829. Im Laufe des 19. Jahrhunderts breitete sich die Art mit einer Geschwindigkeit von etwa 30 km/Jahr nach Westen aus. Ausbreitungsgeschwindigkeit und das gegenwärtige Areal können nur mit Hilfe klimatischer (Ozeanität) und anthropogener Faktoren erklärt werden. Der Mensch trägt vor allem zur Verbreitung vegetativer Pflanzenteile bei und schafft in Siedlungen günstige Wachstumsbedingungen. [source] Yeast diversity of Ghanaian cocoa bean heap fermentationsFEMS YEAST RESEARCH, Issue 5 2009Heide-Marie Daniel Abstract The fermentation of the Theobroma cacao beans, involving yeasts, lactic acid bacteria, and acetic acid bacteria, has a major influence on the quality of the resulting cocoa. An assessment of the microbial community of cocoa bean heap fermentations in Ghana resulted in 91 yeast isolates. These were grouped by PCR-fingerprinting with the primer M13. Representative isolates were identified using the D1/D2 region of the large subunit rRNA gene, internal transcribed spacer sequences and partial actin gene sequences leading to the detection of 15 species. Properties of importance for cocoa bean fermentation, namely sucrose, glucose, and citrate assimilation capacity, pH-, ethanol-, and heat-tolerance, were examined for selected isolates. Pichia kudriavzevii (Issatchenkia orientalis), Saccharomyces cerevisiae, and Hanseniaspora opuntiae formed the major components of the yeast community. Hanseniaspora opuntiae was identified conclusively for the first time from cocoa fermentations. Among the less frequently encountered species, Candida carpophila, Candida orthopsilosis, Kodamaea ohmeri, Meyerozyma (Pichia) caribbica, Pichia manshurica, Saccharomycodes ludwigii, and Yamadazyma (Pichia) mexicana were not yet documented from this substrate. Hanseniaspora opuntiae was preferably growing during the earlier phase of fermentation, reflecting its tolerance to low pH and its citrate-negative phenotype, while no specific temporal distribution was recognized for P. kudriavzevii and S. cerevisiae. [source] Interannual changes in sablefish (Anoplopoma fimbria) recruitment in relation to oceanographic conditions within the California Current SystemFISHERIES OCEANOGRAPHY, Issue 1 2006MICHAEL J. SCHIRRIPA Abstract Sablefish (Anoplopoma fimbria) supports substantial fisheries in both the eastern and western Pacific Oceans. Juvenile recruitment along the west coast of the continental United States has been highly variable over the past three decades. Using a generalized additive model, we demonstrate that physical oceanographic variables within the California Current System have significant effects on sablefish recruitment. Significant relationships were found between juvenile recruitment and northward Ekman transport, eastward Ekman transport, and sea level during key times and at key locations within the habitat of this species. The model explains nearly 70% of the variability in sablefish recruitment between the years 1974 and 2000. The predictive power of the model was demonstrated by refitting without the last 5 yr of data and subsequent prediction of those years. Bootstrap assessments of bias associated with parameter estimates and jackknife-after-bootstrap assessments of the influence of individual data on parameter estimates are presented and discussed. Using this model, it is possible to draw preliminary conclusions concerning year-class strength of cohorts not yet available to the survey gear as well as historic year-class strengths. We discuss changes in zooplankton abundance and shifts in species of copepods associated with fluctuations in the physical variables that appear to have a major influence on sablefish recruitment. [source] Cre-loxP mediated control of PrP to study transmissible spongiform encephalopathy diseasesGENESIS: THE JOURNAL OF GENETICS AND DEVELOPMENT, Issue 1 2004Nadia L. Tuzi Abstract Expression of the PrP glycoprotein is essential for the development of the transmissible spongiform encephalopathy (TSE) or prion diseases. Although PrP is widely expressed in the mouse, the precise relevance of different PrP-expressing cell types to disease remains unclear. To address this, we generated two lines of floxed PrP gene-targeted transgenic mice using the Cre recombinase- loxP system. These floxed mice allow a functional PrP allele to be either switched "on" or "off." We demonstrate control of PrP expression for both alleles following Cre-mediated recombination, as determined by PrP mRNA and protein expression in the brain. Moreover, we show that Cre-mediated alteration of PrP expression in these mice has a major influence on the development of TSE disease. These floxed PrP mice will allow the involvement of PrP expression in specific cell types following TSE infection to be defined, which may identify potential sites for therapeutic intervention. genesis 40:1,6, 2004. © 2004 Wiley-Liss, Inc. [source] Resource settings have a major influence on the outcome of maintenance hemodialysis patients in South IndiaHEMODIALYSIS INTERNATIONAL, Issue 2 2010ABRAHAM Georgi Abstract Chronic kidney disease is reaching epidemic proportions and the number of patients on renal replacement therapy (RRT) is increasing worldwide and also in developing countries. To meet the challenge of providing RRT, a few charity organizations provide hemodialysis units for underprivileged patients, as the private hospitals are unaffordable for the majority. There is a paucity of information on the outcome of dialysis in these patients. Here, we describe the outcome of hemodialysis patients comparing the middle- and upper-class income group with the lower class income group. A retrospective analysis was carried out in 558 CKD patients initiated on maintenance hemodialysis in two different dialysis facilities. Group A (n=247) included those who belonged to the lowermost socioeconomic status and were undergoing dialysis in two nonprofit, charity (TANKER)-run dialysis units, and Group B (n=311) was undergoing dialysis in a nonprofit hospital setting where no subsidy was given. Those patients of a low socioeconomic status, especially those who are diabetics, have a higher death rate (Group A-38.1%, Group B-4.2%) and loss to follow-up (Group A-25.9%, Group B-0.3%) compared with those who are in the middle- and high-income group. Higher EPO use and hence higher hemoglobin levels (Group A-6.4±1.2, Group B-8.9±1.5 P<0.001) were observed in those who were in the middle and the higher income group. Lower serum phosphorus level was observed in the low-socioeconomic group (Group A-4.7±1.5, Group B-5.5±1.9, P<0.001). Patients belonging to the middle and higher socioeconomic group undergo more transplantations compared with the lower socioeconomic group (Group A-2.4%, Group B-65.6%). [source] Simulating soil-water movement under a hedgerow surrounding a bottomland reveals the importance of transpiration in water balanceHYDROLOGICAL PROCESSES, Issue 5 2008Z. Thomas Abstract The objective of this study was to quantify components of the water balance related to root-water uptake in the soil below a hedgerow. At this local scale, a two-dimensional (2D) flow domain in the x,z plane 6 m long and 1·55 m deep was considered. An attempt was made to estimate transpiration using a simulation model. The SWMS-2D model was modified and used to simulate temporally and spatially heterogeneous boundary conditions. A function with a variable spatial distribution of root-water uptake was considered, and model calibration was performed by adjusting this root-water uptake distribution. Observed data from a previous field study were compared against model predictions. During the validation step, satisfactory agreement was obtained, as the difference between observed and modelled pressure head values was less than 50 cm for 80% of the study data. Hedge transpiration capacity is a significant component of soil-water balance in the summer, when predicted transpiration reaches about 5·6 mm day,1. One of the most important findings is that hedge transpiration is nearly twice that of a forest canopy. In addition, soil-water content is significantly different whether downslope or upslope depending on the root-water uptake. The high transpiration rate was mainly due to the presence of a shallow water table below the hedgerow trees. Soil-water content was not a limiting factor for transpiration in this context, as it could be in one with a much deeper water table. Hedgerow tree transpiration exerts a strong impact not only on water content within the vadose zone but also on the water-table profile along the transect. Results obtained at the local scale reveal that the global impact of hedges at the catchment scale has been underestimated in the past. Transpiration rate exerts a major influence on water balance at both the seasonal and annual scales for watersheds with a dense network of hedgerows. Copyright © 2007 John Wiley & Sons, Ltd. [source] Wet and dry summers in Europe since 1750: evidence of increasing droughtINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2009K. R. Briffa Abstract Moisture availability across Europe is calculated based on 22 stations that have long instrumental records for precipitation and temperature. The metric used is the self-calibrating Palmer Drought Severity Index (scPDSI) which is based on soil moisture content. This quantity is calculated using a simplified water budget model, forced by historic records of precipitation and temperature data, where the latter are used in a simple parameterization for potential evaporation. The precipitation and temperature records are updated to include the 2003 summer and all records, except for one, span at least 200 years, with the record for Kew going back to 1697. The Kew record shows a significant clustering of dry summers in the most recent decade. When all the records are considered together, recent widespread drying is clearly apparent and highly significant in this long-term context. By substituting the 1961,1990 climatological monthly mean temperatures for the actual monthly means in the parameterization for potential evaporation, an estimate is made of the direct effect of temperature on drought. This analysis shows that a major influence on the trend toward drier summer conditions is the observed increase in temperatures. This effect is particularly strong in central Europe. Based on the 22 scPDSI records, a gridded scPDSI dataset covering a large part of Europe has been constructed and compared to a recent high-resolution scPDSI dataset spanning the twentieth century only. We again observe that a major cause for the large areal extent of summer drought in the last two decades is high temperatures. Temperatures in the 12 months preceding and including the summer of 2003 explain an increase in the areas experiencing slightly dry (or worse) conditions of 11.1%. Copyright © 2009 Royal Meteorological Society [source] Twenty-three deaths with ,-hydroxybutyrate overdose in western Sweden between 2000 and 2007ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2010K. KNUDSEN Background: ,-Hydroxybutyrate (GHB) is a drug of abuse with a status as being safe. In spite of a reputation of low toxicity, a huge number of deaths associated with this drug have been recorded during recent years in Sweden. It is unclear whether coingestion with other drugs or ethanol causes death in GHB overdoses or whether GHB itself is the main cause of death. Objectives: The aim of this study was to analyze the cause of death in GHB-related fatalities seen in our region. Methods: All cases of deaths with GHB during the year 2000,2007 in the region of western Sweden were studied retrospectively. The cases were classified as either GHB poisonings without any, with a minor or a major influence of other drugs on the cause of death. Results: Twenty-three cases were diagnosed as deaths due to GHB overdose. Ninety-one percent coingested other substances. Ninety-one percent of the decedents were male. Age varied between 16 and 46, with the median age at 25 years. Forty-three percent of the cases were classified as GHB poisonings without any or a minor influence of other drugs on the cause of death. Thirty percent also ingested ethanol. Two patients (9%) were only intoxicated with GHB. Conclusions: Intoxication with GHB carries some mortality. Combining GHB with ethanol does not explain the many deaths in our region, nor do extremely high plasma concentrations of GHB. The intake of opioids increases the toxicity of GHB. The drug itself has such biological activities that an overdose is dangerous and may lead to death. [source] The distribution of file transmission duration in the webINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 5 2004R. Nossenson Abstract It is well known that the distribution of files transmission duration in the Web is heavy-tailed (A practical guide to Heavy Tails: Statistical Techniques and Application. Birkhauser: Boston, 1998; 3,26). This paper attempts to understand the reasons for this phenomenon by isolating the three major factors influencing the transmission duration: file size, network conditions and server load. We present evidence that the transmission-duration distribution (TDD) of the same file from the same server to the same client in the Web is Pareto and therefore heavy tailed. Furthermore, text files transmission delay for a specific client/server pair is not significantly affected by the file sizes: all files transmitted from the same server to the same client have very similar transmission duration distributions, regardless of their size. We use simulations to estimate the impact of network conditions and server load on the TDD. When the server and the client are on the same local network, the TDD of each file is usually Pareto as well (for server files and client requests that are distributed in a realistic way). By examining a wide-area network situation, we conclude that the network conditions do not have a major influence on the heavy-tailed behaviour of TDD. In contrast, the server load is shown to have a significant impact on the high variability of this distribution. Copyright © 2004 John Wiley & Sons, Ltd. [source] Ranking factors of an investment in cogeneration: Sensitivity analysis ranking the technical and economical factorsINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 3 2001Gunnel Sundberg Abstract A deregulation of the electricity market in Europe will result in increased competition among the power-producing companies. They will therefore carefully estimate the financial risk in an investment in new power-producing capability. One part of the risk assessment is to perform a sensitivity analysis. This paper presents a sensitivity analysis using factorial design, resulting in an assessment of the most important technical and economical factors affecting an investment in a gas turbine combined cycle and a steam cycle fired by woodchips. The study is performed using a simulation model that optimizes the operation of existing power plants and potential new investments to fulfil the desired heat demand. The local utility system analysed is a Swedish district heating system with 655 GWh y,1 heat demand. The conclusion is that to understand which of the technical and economical factors affect the investment, it is not sufficient to investigate the parameters of the studied plant, but also the parameters related to the competing plants. Both the individual effects of the factors and the effect of their interaction should be investigated. For the energy system studied the price of natural gas, price of woodchips and investment cost have the major influence on the profitability of the investment. Copyright © 2001 John Wiley & Sons, Ltd. [source] Cationic Ruthenium-Cyclopentadienyl-Diphosphine Complexes as Catalysts for the Allylation of Phenols with Allyl Alcohol; Relation between Structure and Catalytic Performance in O - vs.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009C -Allylation Abstract A new catalytic method has been investigated to obtain either O - or C -allylated phenolic products using allyl alcohol or diallyl ether as the allyl donor. With the use of new cationic ruthenium(II) complexes as catalyst, both reactions can be performed with good selectivity. Active cationic Ru(II) complexes, having cyclopentadienyl and bidentate phosphine ligands are generated from the corresponding Ru(II) chloride complexes with a silver salt. The structures of three novel (diphosphine)Ru(II)CpCl catalyst precursor complexes are reported. It appears that the structure of the bidentate ligand has a major influence on catalytic activity as well as chemoselectivity. In addition, a strong cocatalytic effect of small amounts of acid is revealed. Model experiments are described that have been used to build a reaction network that explains the origin and evolution in time of both O -allylated and C -allylated phenolic products. Some mechanistic implications of the observed structure vs. performance relation of the [(diphosphine)RuCp]+ complexes and the cocatalytic role of added protons are discussed. [source] Electrospinning of degradable elastomeric nanofibers with various morphology and their interaction with human fibroblastsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Erik Borg Abstract Artelon® (degradable poly(urethane urea) elastomer) was electrospun into scaffolds for tissue engineering. The diameter of the electrospun fibers, studied by scanning electron microscopy, ranged from 100 nm to a few ,m, with an average diameter of 750 nm. The molar mass of the polymer had a major influence on the morphology of the scaffold. Furthermore, aging of the polymer solution caused changes in viscosity, as measured by stress sweeps between 13.5,942 Pa that affected the morphology. The electrospun Artelon mats exhibited about the same elongations to break, both exceeding 200%, measured by tensile tests. The degradation study showed similar degradation behavior in electrospun mats and solids. In vitro study showed that human fibroblasts not only adhere to the surface but also migrate, proliferate, and produce components of an extracellular matrix. These results strongly support the use of electrospun Artelon as a scaffold in tissue engineering. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Using historical ecology to understand patterns of biodiversity in fragmented agricultural landscapesJOURNAL OF BIOGEOGRAPHY, Issue 11 2005Ian D. Lunt Abstract Aim, To enhance current attempts to understand biodiversity patterns by using an historical ecology approach to highlight the over-riding influence of land-use history in creating past, current and future patterns of biodiversity in fragmented agricultural landscapes. Methods, We develop an integrative conceptual framework for understanding spatial and temporal variations in landscape patterns in fragmented agricultural landscapes by presenting five postulates (hypotheses) which highlight the important role of historical, anthropogenic disturbance regimes. We then illustrate each of these postulates with examples drawn from fragmented woodlands in agricultural areas of south-eastern Australia, and discuss these findings in an international context. Location examples are drawn from agricultural areas in south-eastern Australia. Results, We conclude that there is limited potential to refine our understanding of patterns of biodiversity in human-modified landscapes based on traditional concepts of island biogeography, or simple assumptions of ongoing destruction and degradation. Instead, we propose that in agricultural landscapes that were largely cleared over a century ago: (1) present-day remnant vegetation patterns are not accidental, but are logically arrayed due to historic land-use decisions, (2) historic anthropogenic disturbances have a major influence on current ecosystem conditions and diversity patterns, and (3) the condition of remnant ecosystems is not necessarily deteriorating rapidly. Main conclusions, An historical ecology approach can enhance our understanding of why different species and ecosystem states occur where they do, and can explain internal variations in ecological conditions within remnant ecosystems, too often casually attributed to the ,mess of history'. This framework emphasizes temporal changes (both past and future) in biotic patterns and processes in fragmented agricultural landscapes. Integration of spatially and temporally explicit historical land-use information into ecological studies can prove extremely useful to test hypotheses of the effects of changes in landscape processes, and to enhance future research, restoration and conservation management activities. [source] Evolutionary divergence and possible incipient speciation in post-glacial populations of a cosmopolitan aquatic plantJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2005G. Nies Abstract Habitat configuration is expected to have a major influence on genetic exchange and evolutionary divergence among populations. Aquatic organisms occur in two fundamentally different habitat types, the sea and freshwater lakes, making them excellent models to study the contrasting effects of continuity vs. isolation on genetic divergence. We compared the divergence in post-glacial populations of a cosmopolitan aquatic plant, the pondweed Potamogeton pectinatus that simultaneously occurs in freshwater lakes and coastal marine sites. Relative levels of gene flow were inferred in 12 lake and 14 Baltic Sea populations in northern Germany using nine highly polymorphic microsatellite markers developed for P. pectinatus. We found highly significant isolation-by-distance in both habitat types (P < 0.001). Genetic differentiation increased approximately 2.5-times faster among freshwater populations compared with those from the Baltic Sea. As different levels of genetic drift or population history cannot explain these differences, higher population connectivity in the sea relative to freshwater populations is the most likely source of contrasting evolutionary divergence. These findings are consistent with the notion that freshwater angiosperms are more conducive to allopatric speciation than their life-history counterparts in the sea, the relative species poor seagrasses. Surprisingly, population pairs from different habitat types revealed almost maximal genetic divergence expected for complete reproductive isolation, regardless of their respective geographical distance. Hence, the barrier to gene flow between lake and sea habitat types cannot be due to dispersal limitation. We may thus have identified a case of rapid incipient speciation in post-glacial populations of a widespread aquatic plant. [source] Otolith-based analysis of survival and size-selective mortality of stocked 0+ year pike related to time of stockingJOURNAL OF FISH BIOLOGY, Issue 6 2004P. Grønkjær The effect of time of stocking on the extent and source of mortality in 0+ year pike Esox lucius was investigated in a lake (20 ha) and a drainable pond (0·5 ha) using pike with alizarin marked otoliths. The results indicated that pike stocked late relative to the recruitment of native 0+ year pike fell victim to cannibalism from these larger individuals. This resulted in very low survival through the first growing season (<2%). Pike stocked early in the season exhibited significantly higher survival (>12%). Analyses of the size distribution of the alizarin marks from these fish revealed that the largest 0+ year pike exhibited by a factor of 3·3, higher survival than the average 0+ year pike in the lake. In order for large 0+ year pike to exhibit such high relative fitness a minimum of 69·7% of the original population must suffer size dependent mortality. In the pond the survival of the largest pike was by a factor of 4·2 higher than the average pike, and the corresponding size dependent mortality was 76·4%. The substantial size-dependent mortality was most probably due to intra-cohort cannibalism or habitat segregation between large and small 0+ year pike that exposes the small pike to predatory fishes in the open lake. Cannibalism exerts a major influence on the survival of 0+ year pike post-stocking although the magnitude and origin differ in relation to stocking time. [source] LOCATION EFFECTS ON OXIDATIVE STABILITY OF CHÉTOUI VIRGIN OLIVE OILJOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2006SONIA BEN TEMIME ABSTRACT The effect of growing area on the natural antioxidant and oxidative stability of Chétoui virgin olive oil was studied. Total phenolic content, tocopherol composition, fatty acid composition and oxidative stability were analyzed. The results obtained in this study showed that Chétoui virgin olive oil composition is greatly influenced by growing environment, i.e., mainly by the climatic and pedologic factors. The cumulative rainfall appears to have a major influence on phenolic and o -diphenol content. Among studied samples, Amdoun oil had the highest total phenolic content, which exceeded 700 mg/kg. Moreover, it contained the highest amounts of o -diphenols 286.08 ± 6.74 mg/kg and total tocopherols 405.65 ± 4.17 mg/kg. The amounts of total phenols and o -diphenols showed a good correlation (P , 0.001) with stability while tocopherols showed a very low relation to oxidative stability. [source] Alternative Scenarios for Managing the Environmental Performance of a Service Sector CompanyJOURNAL OF INDUSTRIAL ECOLOGY, Issue 4 2006Seppo Junnila Summary This article presents a scenario analysis for a life-cycle model of service sector companies. The model is based on six case companies and it is applied to test the influence of 32 management scenarios. The scenarios simulate feasible options for environmental management measures in companies, and the life-cycle assessment method is used to model their relevance in terms of the total environmental impact of the company. The study found that the bulk of tested scenarios had only a minor influence on the total environmental impact of the company. Some individual management scenarios, though, turned out to have a major influence on the organization's environmental performance. The scenarios with greatest influence were those related to the procurement of electricity, building energy consumption, commuting vehicle mix, space usage efficiency, and refurbishment periods of the building. All of these management scenarios had an influence of more than 10% on the environmental impact of the model organization. [source] An Integrative Framework for Measuring the Extent to which Organizational Variables Influence the Success of Process Improvement ProgrammesJOURNAL OF MANAGEMENT STUDIES, Issue 7 2005Peter Lok abstract Studies on the three types of process improvement programmes (Continuous Improvement, Reengineering and Benchmarking) have appeared many times in the literature. These studies suggest that certain organizational variables act as enablers and their presence or absence can significantly influence success rates. Such studies have tended to examine companies where a single programme has been implemented. In contrast, this paper examines a sample of companies who have experienced all three programmes. Our aim is to compare and contrast each programme's impact on firm performance and identify which organizational variables are common and which are programme-specific enablers of success. We build and test an integrative framework to support our analysis. Our study found that: (1) Reengineering delivered the greatest impact on performance; (2) executive commitment was needed to make this happen; (3) strategic alignment was the major influence on the success rate of Reengineering and Continuous Improvement programmes; and (4) employee empowerment was necessary for each programme to work effectively. [source] The FIC1 gene: structure and polymorphisms in baboonJOURNAL OF MEDICAL PRIMATOLOGY, Issue 1 2002Laura A. Cox A genome scan performed on 648 pedigreed baboons to detect and localize quantitative trait loci (QTL) for lipoprotein phenotypes that are known risk factors for atherosclerosis indicated the presence of a QTL on chromosome 18q that exerts a major influence on HDL-cholesterol (HDL-C) related phenotypes. Inspection of the human gene map revealed that the familial intrahepatic cholestatis gene 1 (FIC1) maps to the homologous region of baboon chromosome 18 containing the major QTL influencing HDL-C phenotypes. FIC1 is a strong biological candidate for this QTL because HDL-C is the preferred precursor for bile acid synthesis. In this study, we cloned and sequenced FIC1 cDNA and found that it is highly conserved between human and baboon. We also sequenced FIC1 cDNAs from a panel of unrelated baboons revealing single nucleotide polymorphisms (SNPs) and a polymorphic dinucleotide repeat. None of the baboon SNPs corresponded to human FIC1 mutations associated with familial intrahepatic cholestasis or benign recurrent intrahepatic cholestasis disorders. [source] Effects of matrix grain size on the kinetics of intergranular diffusionJOURNAL OF METAMORPHIC GEOLOGY, Issue 8 2004W. D. Carlson Abstract A linear relationship exists between the mean volume of garnet porphyroblasts and the squared inverse of mean matrix grain diameter for six samples of garnetiferous mica quartzite with identical thermal histories and similar mineralogy and modes. This relationship accords with theoretical predictions of the dependence of intergranular diffusive fluxes on the volume fraction of grain edges that function as diffusional pathways during porphyroblast growth. The impact of matrix grain size is large: compared to a rock with a 1-mm matrix, a rock with a 10- ,m matrix would experience rates of diffusion-controlled porphyroblast growth that are 10 000 times faster, and characteristic length scales for chemical equilibration that are 100 times larger. Precursor grain sizes may therefore exert a major influence on crystallization kinetics. If matrix coarsening occurs during prograde reaction, a decrease in the volume fraction of diffusional pathways will tend to counteract the exponential thermal increase in diffusive fluxes. The impact of such matrix grain growth, although difficult to assess without firm knowledge of coarsening rates in polymineralic aggregates, might be significant for matrices finer than c. 100 ,m at temperatures above c. 500,600 °C, but is likely negligible for coarser grain sizes and lower temperatures. [source] Living with a spouse with chronic obstructive pulmonary disease: the meaning of wives' experiencesJOURNAL OF NURSING AND HEALTHCARE OF CHRONIC ILLNE SS: AN INTERNATIONAL INTERDISCIPLINARY JOURNAL, Issue 4 2009Anne H Boyle PhD Aim., To describe and understand the meaning of the experience of living with a spouse who has chronic obstructive pulmonary disease. Background., Living with a spouse with a chronic illness may have a profound effect on women's lives since society expects families, and especially women, to care for the chronically ill. The family member providing care and support is usually the wife. Design., This study investigated the wife's experience of living with a husband's chronic illness. A hermeneutic phenomenological approach was used to describe and understand the experience of women living with a spouse who has chronic obstructive pulmonary disease to determine the meaning this experience has for their lives. Methods., In-depth interviews were conducted with ten women whose husbands had mild to severe obstructive lung disease. Thematic analysis was based on interpretive methods. Data were collected in 1997. Results., The findings are presented as two clusters, living with everyday illness and surviving the illness. Everyday illness includes monitoring, regulating activity, integrating illness effects, and managing technologies. Surviving the illness includes riding the roller coaster, keep on going, garnering support and finding explanations. Conclusions., The spouse's illness had a major influence on these women's lives, and the effects are very complex and interwoven with one another. Relevance to clinical practice., Health professionals can have a major role in assisting women to both live with the everyday illness and to survive its effects. Women were eager to tell their stories. Health professionals can help women deal with the experience by forming support groups and by asking the ,How can I help?' question more often and then actively listening to expressed concerns. Supporting women in their monitoring and regulating role is especially critical. [source] | ||||||||||||||||||||||||||||||||||