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Complete Block Design (complete + block_design)
Kinds of Complete Block Design Selected AbstractsCumulative Damage Survival Models for the Randomized Complete Block DesignBIOMETRICAL JOURNAL, Issue 2 2003Gavin G. Gregory Abstract A continuous time discrete state cumulative damage process {X(t), t , 0} is considered, based on a non-homogeneous Poisson hit-count process and discrete distribution of damage per hit, which can be negative binomial, Neyman type A, Polya-Aeppli or Lagrangian Poisson. Intensity functions considered for the Poisson process comprise a flexible three-parameter family. The survival function is S(t) = P(X(t) , L) where L is fixed. Individual variation is accounted for within the construction for the initial damage distribution {P(X(0) = x) | x = 0, 1, ,,}. This distribution has an essential cut-off before x = L and the distribution of L , X(0) may be considered a tolerance distribution. A multivariate extension appropriate for the randomized complete block design is developed by constructing dependence in the initial damage distributions. Our multivariate model is applied (via maximum likelihood) to litter-matched tumorigenesis data for rats. The litter effect accounts for 5.9 percent of the variance of the individual effect. Cumulative damage hazard functions are compared to nonparametric hazard functions and to hazard functions obtained from the PVF-Weibull frailty model. The cumulative damage model has greater dimensionality for interpretation compared to other models, owing principally to the intensity function part of the model. [source] Agronomic performance and nutritive value of common and alternative grass and legume species in the Peruvian highlandsGRASS & FORAGE SCIENCE, Issue 2 2009K. Bartl Abstract The agronomic performance and nutritive value of twelve annual and perennial grasses and legumes were analysed in order to define alternatives to local forages for dry-season feeding of ruminants in the Peruvian Andes. There were twelve species and two fertilizer treatments (no fertilizer and a N;P;K fertilizer mainly applied at sowing) in an experiment with a randomized complete block design with three replicates at each of two sites. Plant height, soil cover by forage and weed species, frost damage, dry matter (DM) yield and nutritive value of herbage were evaluated in 2005 and 2006. Among the annual species, Hordeum vulgare L. cv. UNA 80 and ×Triticosecale Wittm. had the highest DM yields when fertilized (8226 and 6934 kg ha,1 respectively). Without fertilizer the alternative cultivars had similar DM yields to that of the local forages. Cultivars of Avena sativa L. had lower concentrations of neutral-detergent fibre (NDF) (557 g kg,1 DM) and higher concentrations of predicted net energy for lactation (5·86 MJ kg,1 DM) than the other annual grass species (625 g kg,1 DM and 5·01 MJ kg,1 DM respectively), while the legumes were superior in concentrations of crude protein (277 g kg,1 DM) and NDF (362 g kg,1 DM). Considering the low agronomic performance of the perennial forages, a mixture of fertilized annual grasses and legumes appears the most appropriate approach to meeting the demand for forage of high nutritive value in the Peruvian highlands. [source] Changes in the physiology and feed quality of cocksfoot (Dactylis glomerata L.) during regrowthGRASS & FORAGE SCIENCE, Issue 3 2002R. P. Rawnsley Abstract A glasshouse study was undertaken to determine the physiological and morphological changes in cocksfoot (Dactylis glomerata L.) during regrowth after defoliation. Individual plants were arranged in a mini-sward in a randomized complete block design. Treatments involved harvesting each time one new leaf had expanded (one-leaf stage), up to the six-leaf stage, with the plants separated into leaf, stubble (tiller bases) and roots. Stubble and root water-soluble carbohydrate (WSC), stubble and leaf dry matter (DM), tiller number per plant and leaf quality (crude protein (CP), estimated metabolizable energy (ME) and mineral content) were measured to develop optimal defoliation management of cocksfoot-based pastures. WSC concentration in stubble and roots was highest at the five- and six-leaf stages. Mean WSC concentration (g kg,1 DM) was greater in stubble than roots (32·7 ± 5·9 vs. 9·4 ± 1·5 respectively). There was a strong positive linear relationship between plant WSC concentration and leaf DM, root DM and tillers per plant after defoliation (Adj R2 = 0·72, 0·88 and 0·95 respectively). Root DM plant,1 and tiller DM tiller,1 decreased immediately following defoliation and remained low until the three-leaf stage, then increased from the four-leaf stage. Tillers per plant remained stable until the four-leaf stage, after which they increased (from 9·9 ± 0·5 to 15·7 ± 1·0 tillers plant,1). Estimated metabolizable energy concentration (MJ kg,1 DM) was significantly lower at the six-leaf stage (11·01 ± 0·06) than at any previous leaf regrowth stage, whereas CP concentration (g kg,1 DM) decreased with regrowth to the six-leaf stage. Both the levels of ME and CP concentrations were indicative of a high quality forage throughout regrowth (11·37 ± 0·04 and 279 ± 8·0 for ME and CP respectively). Results from this study give a basis for determining appropriate criteria for grazing cocksfoot-based pastures. The optimal defoliation interval for cocksfoot appears to be between the four- and five-leaf stages of regrowth. Delaying defoliation to the four-leaf stage allows time for replenishment of WSC reserves, resumption of root growth and an increase in tillering, and is before herbage is lost and quality falls due to onset of leaf senescence. [source] Changes in total carotenoid content at different stages of traditional processing of yellow-fleshed cassava genotypesINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2009Busie Maziya-Dixon Abstract The changes in content of total carotenoid at each stage of processing cassava storage roots were investigated with three improved yellow-fleshed cassava varieties (TMS 94/0006, TMS 01/1235 and TMS 01/1371) grown in 2005/2006 in a randomised complete block design with two replications at Ibadan, Nigeria. When the cassava roots were grated to a mash, results obtained indicate that there was a significant reduction in total carotenoid content for all the genotypes. The reduction was highest for TMS 01/1235 (1.20 ,g g,1), intermediate for TMS 01/1371 (0.78 ,g g,1) and least for TMS 94/0006 (0.35 ,g g,1). In most cases, we observed higher total carotenoid concentration, especially when the intermediate step involved pressing to remove excess water, and during roasting compared with the initial concentration in the raw cassava storage roots. In conclusion, grating, drying and cooking to a paste resulted in reduction of total carotenoid content, while roasting and pressing resulted in higher carotenoid concentration. A change in total carotenoid content during processing depends on variety, processing method, especially unit operation and the initial total carotenoid content of the variety. [source] Assessment of the water,salinity crop production function of wheat using experimental data of the Golestan province, Iran,IRRIGATION AND DRAINAGE, Issue 4 2009A. R. Kiani stress hydrique; stress de salinité; fonctions de production; blé Abstract Optimisation of agricultural water management in arid and semi-arid regions requires the availability of water,salinity crop production functions. A two-year experiment was conducted in the northern Golestan province of Iran to assess the water,salinity production function of wheat. The treatments in the experiment consisted of four levels of irrigation water, i.e. 50 (W1), 75 (W2), 100 (W3) and 125 (W4) % of crop water requirement, and four levels of water salinity, respectively 1.5 (S1), 8.5 (S2), 11.5 (S3) and 14.2 (S4) dS,m,1. The plots were arranged in a randomised complete block design with three replications and water quantity as main plot treatment and water quality as subplot treatment. The data were analysed using linear, quadratic, Cobb,Douglas and transcendental functions, complemented with an economic analysis. The results indicate that for the given climate,soil conditions, transcendental functions best predict wheat yield under both water and salinity stress conditions. Yield reduction caused by a unit increase of matric potential is found to be larger than that caused by a unit increase of osmotic potential. The marginal rate of technical substitution indicates that each one of the two factors studied, namely soil salinity and water supply, can be substituted with the other in a wide range in order to achieve equal amount of yield. Copyright © 2008 John Wiley & Sons, Ltd. L'optimisation de la gestion de l'eau agricole dans les zones arides et semi-arides nécessite de savoir la relation entre l'apport d'eau selon sa salinité et la production végétale. Une expérience de deux ans a été menée dans le nord de la province du Golestan en Iran pour évaluer la fonction de production de l'eau saline sur le blé. Les traitements expérimentaux consistaient en quatre niveaux d'apports d'eau soit 50% (W1), 75% (W2), 100% (W3) et 125% (W4) des besoins en eau des cultures, et quatre niveaux de salinité de l'eau, respectivement 1.5 (S1), 8.5 (S2), 11.5 (S3) et 14.2 (S4) dS,m,1. Les parcelles ont été disposées dans un bloc de Fisher randomisé avec trois répétitions avec la quantité de l'eau comme variable principale et la qualité de l'eau comme variable secondaire. Les données ont été analysées en utilisant les fonctions linéaires, quadratiques, Cobb,Douglas et transcendantes, complétées par une analyse économique. Les résultats indiquent que, pour un climat et un état du sol donnés, les fonctions transcendantes donnent les meilleures prédictions du rendement de blé en condition de salinité et de stress hydrique. La baisse de rendement causée par une augmentation d'une unité de potentiel hydrique est plus importante que celle causée par l'augmentation d'une unité de potentiel osmotique. Le taux marginal de substitution technique indique que chacun des deux facteurs étudiés, à savoir la salinité des sols et l'apport d'eau, peuvent être largement substitués l'un à l'autre pour viser rendement identique. Copyright © 2008 John Wiley & Sons, Ltd. [source] Determination of the selenium requirement in kittens,JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 9-10 2003K. J. Wedekind Summary The purpose of this study was to determine the selenium (Se) requirement in kittens. Thirty-six specific-pathogen-free kittens (9.8 weeks old) were utilized in a randomized complete block design to determine the Se requirement in cats with gender and weight used as blocking criteria. Kittens were fed a low Se (0.02 mg/kg Se) torula yeast-based diet for 5 weeks (pre-test) after which an amino acid-based diet (0.027 mg Se/kg diet) was fed for 8 weeks (experimental period). Six levels of Se (0, 0.05, 0.075, 0.10, 0.20 and 0.30 mg Se/kg diet) as Na2SeO3 were added to the diet and were used to construct a response curve. Response variables included Se concentrations and Se-dependent glutathione peroxidase activities (GSHpx) in plasma and red blood cells (RBC) as well as plasma total T3 (TT3) and total T4 (TT4). No significant changes in food intake, weight gain or clinical signs of Se deficiency were noted. Estimates of the kitten's Se requirement (i.e. breakpoints) were determined for RBC and plasma GSHpx (0.12 and 0.15 mg Se/kg diet, respectively), but no definitive breakpoint was determined for plasma Se. Plasma TT3 increased linearly, whereas plasma TT4 and the ratio of TT4 : TT3 decreased in a quadratic fashion to dietary Se concentration. The requirement estimate determined in this study (0.15 mg Se/kg) for kittens is in close agreement with other species. As pet foods for cats contain a high proportion of animal protein with a Se bioavailability of 30%, it is recommended that commercial diets for cats contain 0.5 mg Se/kg DM. [source] Testing liana cutting and controlled burning as silvicultural treatments for a logged forest in the eastern AmazonJOURNAL OF APPLIED ECOLOGY, Issue 6 2001Jeffrey J. Gerwing Summary 1In the eastern Brazilian Amazon, logged forests frequently include patches where liana density is particularly high. In these so-called liana tangles, competition from lianas is predicted to reduce tree growth significantly, thus effectively impeding future timber production. To begin to develop a silvicultural strategy for these patches, the impact of liana cutting and controlled burning on liana density, tree growth and tree regeneration in liana-dominated patches was investigated in a logged forest in the eastern Brazilian Amazon. 2The two treatments (liana cutting and controlled burning) and a control were installed in 40 × 40-m plots in a randomized complete block design of six blocks. Treatments were conducted during October 1997, and tree diameter growth and mortality, canopy cover, regeneration and liana density were monitored over 2 years. 3Mean mortality following burning was significantly higher for lianas (79%) than for trees (48%), as was the mean coppicing rate of top-killed stems (42% for lianas vs. 20% for trees). Coppicing combined with some recruitment from seed resulted in liana densities in the burned plots returning to 70% of the values in the control plots only 2 years post-treatment. 4Canopy light transmittance, estimated from hemispherical canopy photographs taken at 1 m above the ground, increased significantly from c. 4% in controls to 8% in cut and 12% in burned treatments, and these differences persisted over the 2-year study period. 5In the absence of silvicultural intervention, mean tree diameter increments were low (1·3 mm year,1), suggesting that the successional transition to higher stature forest was occurring very slowly. Each of the treatments resulted in a more than doubling of mean annual tree growth (3 and 2·8 mm year,1 for liana-cut and burned treatments, respectively). The treatments also significantly reduced the occurrence of trees that showed no growth over the study period, from 56% in controls to 30% in cut and 32% in burned treatments. 6The results of this study suggest that although burning resulted in increased tree growth, rapid recolonization of surviving trees by lianas and the high vulnerability of burned stands to unwanted repeat burns are likely to cancel out any of the possible benefits of controlled burning as a silvicultural treatment for liana-dominated patches. Liana cutting, on the other hand, showed promise and its adoption as part of a larger strategy for the recuperation of the timber production potential of logged tropical forests seems warranted. [source] Paired comparisons for the evaluation of crispness of cereal flakes by untrained assessors: correlation with descriptive analysis and acoustic measurementsJOURNAL OF CHEMOMETRICS, Issue 3 2005Philippe Courcoux Abstract This study investigates the effectiveness of the paired comparison method in the evaluation of a complex sensory attribute by untrained assessors. The crispness perception of cereal flakes by a panel of 100 consumers is measured using a complete block design, and the fitting of the Bradley,Terry,Luce model leads to a ranking of the samples on a crispness intensity scale. A log,linear formulation of the Bradley model provides insight into goodness-of-fit tests and allows the effects of covariates to be incorporated in the prediction of the sensory scores. Results show a high correlation between crispness assessment by consumers and rating of texture attributes by trained assessors. Acoustic emission is shown to have a significant effect on crispness perception, and the power spectra of signals recorded during compression provide a prediction of the crispness of cereal flakes. Copyright © 2005 John Wiley & Sons, Ltd. [source] Bleaching Agents with Varying Concentrations of Carbamide and/or Hydrogen Peroxides: Effect on Dental Microhardness and RoughnessJOURNAL OF ESTHETIC AND RESTORATIVE DENTISTRY, Issue 6 2008JULIANA JENDIROBA FARAONI-ROMANO DDS ABSTRACT Purpose:, To evaluate the effect of low and highly concentrated bleaching agents on microhardness and surface roughness of bovine enamel and root dentin. Methods:, According to a randomized complete block design, 100 specimens of each substrate were assigned into five groups to be treated with bleaching agents containing carbamide peroxide (CP) at 10% (CP10); hydrogen peroxide (HP) at 7.5% (HP7.5) or 38% (HP38), or the combination of 18% of HP and 22% of CP (HP18/CP22), for 3 weeks. The control group was left untreated. Specimens were immersed in artificial saliva between bleaching treatments. Knoop surface microhardness (SMH) and average surface roughness (Ra) were measured at baseline and post-bleaching conditions. Results:, For enamel, there were differences between bleaching treatments for both SMH and Ra measurements (p = 0.4009 and p = 0.7650, respectively). SMH significantly increased (p < 0.0001), whereas Ra decreased (p = 0.0207) from baseline to post-bleaching condition. For root dentin, the group treated with CP10 exhibited the significantly highest SMH value differing from those groups bleached with HP18/CP22, HP7.5, which did not differ from each other. Application of HP38 resulted in intermediate SMH values. No significant differences were found for Ra (p = 0.5975). Comparing the baseline and post-bleaching conditions, a decrease was observed in SMH (p < 0.0001) and an increase in Ra (p = 0.0063). Conclusion:, Bleaching agents with varying concentrations of CP and/or HP are capable of causing mineral loss in root dentin. Enamel does not perform in such bleaching agent-dependent fashion when one considers either hardness or surface roughness evaluations. CLINICAL SIGNIFICANCE Bleaching did not alter the enamel microhardness and surface roughness, but in root dentin, microhardness seems to be dependent on the bleaching agent used. [source] Erythroneura lawsoni abundance and feeding injury levels are influenced by foliar nutrient status in intensively managed American sycamoreAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2010David Robert Coyle 1Abundance and feeding injury of the leafhopper Erythroneura lawsoni Robinson was measured in an intensively-managed American sycamore Platanus occidentalis L. plantation. Trees were planted in spring 2000 in a randomized complete block design, and received one of three annual treatments: (i) fertilization (120 kg N/ha/year); (ii) irrigation (3.0 cm/week); (iii) fertilization + irrigation; or (iv) control (no treatment). 2Foliar nutrient concentrations were significantly influenced by the treatments because only sulphur and manganese levels were not statistically greater in trees receiving fertilization. 3Over 116 000 E. lawsoni were captured on sticky traps during the study. Leafhopper abundance was highest on nonfertilized trees for the majority of the season, and was positively correlated with foliar nutrient concentrations. Significant temporal variation in E. lawsoni abundance occurred, suggesting five discrete generations in South Carolina. 4Significant temporal variation occurred in E. lawsoni foliar injury levels, with the highest injury ratings occurring in late June and August. Foliar injury was negatively correlated with foliar nutrient content, and higher levels of injury occurred more frequently on nonfertilized trees. 5The results obtained in the present study indicated that increased E. lawsoni abundance occurred on trees that did not receive fertilization. Nonfertilized trees experienced greater foliar injury, suggesting that lower foliar nutrient status may have led to increased levels of compensatory feeding. [source] Genetic Analysis of the Latent Period of Stripe Rust in Wheat SeedlingsJOURNAL OF PHYTOPATHOLOGY, Issue 6 2004H. Dehghani Abstract Genetics of slow-rusting resistance to yellow rust (Puccinia striiformis f.sp. tritici) was studied by a half-diallel design using six wheat varieties, Tiritea (susceptible), Tancred, Kotare, Otane, Karamu, and Briscard. The parents and 15 F1 progenies were evaluated in the greenhouse by three pathotypes 7E18A,, 38E0A+, and 134E134A+. The latent period was measured as the number of days from inoculation to the appearance of the first pustule. For each pathotype a randomized complete block design was used and data were analysed by methods of Griffing and Hayman. The range of average degree of dominance was from complete dominance to over-dominance. Positive and negative degrees of dominance were observed for each pathotype that showed the reversal of dominance. Analysis of variance showed the importance of both additive and dominance effects in controlling the latent period. Broad-sense heritabilities were 0.99 and narrow-sense heritabilities ranged from 0.85 to 0.94. Briscard and Karamu for the pathotypes 38E0A+ and 134E134A+, Kotare for the pathotype 7E18A, and Tancred for the pathotype 38E0A+ had significant and positive general combining ability (GCA) (more resistance) for latent period. The crosses of Kotare with Tancred, Briscard and Karamu indicated the highest and positive specific combining ability (SCA) for the pathotype 7E18A,. Significant additive genetic component and moderate narrow-sense heritability indicate the possibility of improving for longer latent period of stripe rust in breeding programmes. [source] Comparison of the cardio-respiratory effects of methadone and morphine in conscious dogs,JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 4 2009A. A. MAIANTE The effects of methadone and morphine were compared in conscious dogs. Six animals received morphine sulfate (1 mg/kg) or methadone hydrochloride (0.5 mg/kg [MET0.5] or 1.0 mg/kg [MET1.0]) intravenously (i.v.) in a randomized complete block design. Cardiopulmonary variables were recorded before (baseline), and for 120 min after drug administration. One outlier was not included in the statistical analysis for hemodynamic data. Morphine decreased heart rate (HR) compared to baseline from 30 to 120 min (,15% to ,26%), while cardiac index (CI) was reduced only at 120 min (,19%). Greater and more prolonged reductions in HR (,32% to ,46%) and in CI (,24% to ,52%) were observed after MET1.0, while intermediate reductions were recorded after MET0.5 (,19 to ,28% for HR and ,17% to ,27% for CI). The systemic vascular resistance index (SVRI) was increased after methadone; MET1.0 produced higher SVRI values than MET0.5 (maximum increases: 57% and 165% for MET0.5 and MET1.0, respectively). Compared to morphine, oxygen partial pressure (PaO2) was lower (,12% to ,13%) at 5 min of methadone (0.5 and 1.0 mg/kg), while carbon dioxide partial pressure (PaCO2) did not change significantly. It was concluded that methadone induces cardiovascular changes that are dose-related and is a more potent cardiovascular depressant agent than morphine in conscious dogs. [source] Water-soluble phosphorus excretion in pigs fed diets supplemented with microbial phytaseANIMAL SCIENCE JOURNAL, Issue 3 2009Joshua A. JENDZA ABSTRACT Three experiments were conducted to compare the excretion of water-soluble phosphorus (P) of starter, grower, and finisher pigs fed corn-soybean meal-based P-deficient basal diet containing no added inorganic P (B), P-adequate diet (the basal diet with added dicalcium phosphate; B + P), the basal diet plus 500 units of microbial phytase/kg (B + 500), or the basal diet plus 1000 units of microbial phytase/kg (B + 1000). There were 6 barrows per diet, in a randomized complete block design, with an average initial body weight of 10.4, 20.0, or 51.1 kg for each of starter, grower, and finisher pigs in the three phosphorus balance experiments, respectively. In the experiments, the addition of dicalcium phosphate or phytase to the basal diet increased (P < 0.05) the digestibility and retention of P, and there were linear reductions (P < 0.05) in water-soluble P excretion as a result of supplementing the basal diet with phytase. In the starter pig experiment, phytase addition at 500 or 1000 units/kg reduced (P < 0.05) water-soluble P excretion by 28 or 42%, respectively when compared with the B + P diet. In the grower pig experiment, adding phytase at 500 or 1000 units/kg reduced (P < 0.05) water-soluble P excretion by 24 or 34%, respectively when compared with the B + P diet. The use of phytase at 500 or 1000 units/kg reduced (P < 0.05) water-soluble P excretion by 11 or 30%, respectively in the finisher pig experiment. The proportion of water-soluble phosphorus in total phosphorus was not affected by dietary treatment in any of the three experiments. In conclusion, adding phytase at 1000 units/kg to a corn-soybean meal-based P-deficient diet basal diet containing no added inorganic P compared with B + P diet reduced the daily excretion of water-soluble P in starter, grower, and finisher pigs by 42, 34, and 30%, respectively. [source] Comparison of the effect of market crop wastes and chemical soil fertility amendments on insect pests, natural enemies and yield of Brassica oleraceaANNALS OF APPLIED BIOLOGY, Issue 2 2006J. Karungi Abstract Field studies were conducted over three growing seasons during 2 years to assess the relative effect of market crop waste (MCW)-derived soil fertility amendments and conventional fertiliser (NPK) on tritrophic relations as well as yield performance of white cabbage. A randomised complete block design with four treatments and a control replicated four times was used. Treatments were (a) MCW compost incorporated in the soil, (b) uncomposted MCW incorporated in the soil, (c) uncomposted MCW applied as surface mulch, (d) a conventional chemical fertiliser (NPK) incorporated in the soil and (e) the untreated control. Results indicated that relative to NPK-amended plants, MCW-amended cabbage performed better in plant growth parameters as well as yield, despite having sustained aphid and Plutella xylostella infestations that could be as much as double as those in the NPK treatment. Natural enemy occurrence followed the trend of host insect infestations. The average yield performance and net financial benefits from MCW-compost-amended plants were three-fold as that of NPK-amended plants. Soil analysis results indicated an advantage in soil quality accruing from the MCW amendments. This study, therefore, provides documentation for the utilisation of MCW, previously handled as garbage to be disposed of, as a key component in integrated management of insect pests and depleted soils in crop production in sub-Saharan Africa and beyond. [source] Effects on vegetation composition of a modified forest harvesting and propagation method compared with clear-cutting, scarification and plantingAPPLIED VEGETATION SCIENCE, Issue 2 2008Johan Bergstedt Question: How does the vegetation of boreal forests respond to harvesting and scarification? Location: 650 m a.s.l., central Sweden (61°38' N). Methods: The response of boreal forest vegetation to cutting and scarification was studied in a field trial, which consisted of three treatments plus conventional harvesting as a control in a complete block design with four replicates. The cutting was done 14 years prior to vegetation inventory and scarification and planting were conducted the first or second years after cutting. Results: The species most abundant at higher cutting intensities were crustose lichens, Cladonia spp., Cladina arbuscula, Polytrichum spp. and pioneer mosses, the grass Deschampsia flexuosa, and the tree Betula pubescens, A few species had substantially lower abundance in treatments with higher cutting intensity, notably Hylocomium splendens and Vaccinium myrtillus. Scarification had a strong effect that was different from the one created by cutting. In scarification treatments, Polytrichum spp. were the only species with high abundance; most species had low abundance, i.e. Barbilophozia lycopodioides, Vaccinium vitis-idaea, Pleurozium schreberi, Carex globularis, Empetrum nigrum, Cladina arbuscula, Sphagnum spp. Conclusions: Our results elaborate on the details of the well-known effect of cutting on ground-layer flora, and also give support for the profound and long-lasting effect that soil scarification has on forest vegetation. [source] Cumulative Damage Survival Models for the Randomized Complete Block DesignBIOMETRICAL JOURNAL, Issue 2 2003Gavin G. Gregory Abstract A continuous time discrete state cumulative damage process {X(t), t , 0} is considered, based on a non-homogeneous Poisson hit-count process and discrete distribution of damage per hit, which can be negative binomial, Neyman type A, Polya-Aeppli or Lagrangian Poisson. Intensity functions considered for the Poisson process comprise a flexible three-parameter family. The survival function is S(t) = P(X(t) , L) where L is fixed. Individual variation is accounted for within the construction for the initial damage distribution {P(X(0) = x) | x = 0, 1, ,,}. This distribution has an essential cut-off before x = L and the distribution of L , X(0) may be considered a tolerance distribution. A multivariate extension appropriate for the randomized complete block design is developed by constructing dependence in the initial damage distributions. Our multivariate model is applied (via maximum likelihood) to litter-matched tumorigenesis data for rats. The litter effect accounts for 5.9 percent of the variance of the individual effect. Cumulative damage hazard functions are compared to nonparametric hazard functions and to hazard functions obtained from the PVF-Weibull frailty model. The cumulative damage model has greater dimensionality for interpretation compared to other models, owing principally to the intensity function part of the model. [source] |