Home About us Contact
|
Home About us Contact | ||
|
|
||
Spatial Differences (spatial + difference)
Selected AbstractsImpact of predators on artificially augmented populations of Lymantria dispar L. pupae (Lep., Lymantriidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 2-3 2002T. Gschwantner The impact of predators on artificially augmented populations of Lymantria dispar pupae (Lep., Lymantriidae) and the species composition of the predator community were investigated in two oak stands in eastern Austria. The population density of L. dispar has been at innocuous levels for several years at both sites. From mid-June to mid-July, we created artificial prey populations by mounting gypsy moth pupae with beeswax on burlap bands placed at the base, 25, 50 and 100 cm height on 25 trees at each site. A total of 6600 pupae were exposed at each site. A total of 92% of exposed pupae were destroyed by predators, at site I (with dense understorey vegetation) whereas 67% were destroyed on site II (with sparse understorey vegetation). Initially, pupal mortality was highest at the base of trees, but differences in mortality among the four locations where pupae were exposed decreased during the course of the study period. Spatial differences in predation were ascertained, suggesting that the aggregation of small mammals, for example, is related to patches of dense shrub vegetation. Pupal mortality was primarily caused by mice (46.3% at site I and 36.4% at site II). Many exposed pupae simply disappeared (40.4% at site I and 22.8% at site II). Calosoma spp. and other invertebrate predators caused very little mortality among L. dispar pupae (5.5% at site I and 7.8% at site II). Trap catches on separate study plots at both sites revealed that Apodemus flavicollis (Rodentia, Muridae) was the most important predator species present, whereas Apodemus sylvaticus (Rodentia, Muridae) and Clethrionomys glareolus (Rodentia, Arvicolidae) were captured in low numbers. [source] Spatial differences in breeding success in the pied avocet Recurvirostra avosetta: effects of habitat on hatching success and chick survivalJOURNAL OF AVIAN BIOLOGY, Issue 4 2006Szabolcs Lengyel I studied the breeding biology of pied avocets Recurvirostra avosetta in natural habitats (alkaline lakes), and in semi-natural sites (dry fishpond, reconstructed wetlands) in Hungary to relate habitat selection patterns to spatial and temporal variation in breeding success. Colonies were initiated earlier in semi-natural sites than in natural habitats, and earlier on islands than on the mainland. Hatching success was higher on islands than on the mainland, in semi-natural sites than in natural habitats, in colonies of at least 15 pairs than in smaller colonies, and for nests initiated earlier than later within a colony. Fledging success was higher in the wet years (1999,2000) than in the dry year (1998), decreased strongly by season in both habitats and increased with average daily temperature in the first week post-hatch in 1999,2000. Most pairs hatching young in semi-natural sites attempted to lead their chicks to feeding areas in natural habitats, whereas no such movement occurred in the opposite direction. Chick mortality due to predation was high during brood movements and only 23% of the pairs moving their young produced fledglings, compared to 43% for pairs remaining in semi-natural sites and 68% for pairs hatching and rearing young in natural habitats (total n=192 broods). These results suggest that semi-natural sites were more suitable for nesting, whereas natural habitats were more suitable for chick-rearing. The opposing trends in habitat-related breeding success between nesting and chick-rearing suggest sub-optimal habitat selection by Pied Avocets due to an incorrect assessment of the potential for successful reproduction of semi-natural sites, which may thus function as ecological traps. [source] Spatial differences in acquisition of soil phosphate between two arbuscular mycorrhizal fungi in symbiosis with Medicago truncatulaNEW PHYTOLOGIST, Issue 2 2000F. A. SMITH Responses of Medicago truncatula to colonization by two arbuscular mycorrhizal fungi, Scutellospora calospora isolate WUM 12(2) and Glomus caledonium isolate RIS 42, were compared in the light of previous findings that the former fungus can be ineffective as a beneficial microsymbiont with some host plants. The plants were grown individually in two-compartment systems in which a lateral side arm containing soil labelled with 33P was separated from the main soil compartment by a nylon mesh that prevented penetration by roots but not fungal hyphae. Fungal inoculum was applied as a root,soil mixture in a band opposite the side arm. Nonmycorrhizal controls were set up similarly, without inoculum. There were harvests at 28, 35, 42 and 49 d. Both sets of mycorrhizal plants grew better than nonmycorrhizal plants and initially had higher concentrations of P in shoots and roots. Plants grown with S. calospora grew better than plants grown with G. caledonium, and this was associated with somewhat greater fungal colonization in terms of intraradical hyphae and numbers of arbuscules. Scutellospora calospora formed denser hyphae at root surfaces than G. caledonium. By 28 d there were extensive hyphae of both fungi in the side arms, and after 35 d S. calospora produced denser hyphae there than G. caledonium. Nevertheless, there was very little transfer of 33P via S. calospora to the plant at 28 d, and thereafter its transfer increased at a rate only c. 33% of that via G. caledonium. The results showed that plants colonized by S. calospora preferentially obtained P from sites in the main soil chamber relatively close to the roots, compared with plants colonized by G. caledonium. Hence formation of a highly beneficial arbuscular mycorrhizal symbiosis does not necessarily depend on development of hyphae at a distance from the roots or on large-scale translocation of P from distant sites. The results are discussed in relation to previous studies with compartmented systems that have involved the same fungi. Possible causes of the variable effects of S. calospora in symbiosis with different host plants are briefly assessed. Differences in spatial abilities of individual arbuscular mycorrhizal fungi to acquire P might have strong ecological implications for plant growth in soils low in P. [source] Seasonal march and its spatial difference of rainfall in the PhilippinesINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 6 2007I. Akasaka Abstract On the basis of the pentad rainfall data averaged from 1961 to 2000, the seasonal march of rainfall in the Philippines is analyzed in this study. The relation to the atmospheric circulation at the 850 hPa level is also discussed. To investigate the temporal and spatial features of rainfall, the Empirical orthogonal function (EOF) analysis was applied to rainfall data. The result showed two dominant modes in the seasonal march of rainfall. The first mode reveals the increase of rainfall amount in the entire Philippines during summer monsoon while the second mode represents the contrast between the west and east coasts in the seasonal march of rainfall. The rainy season starts simultaneously over the entire west coast in the middle of May and withdraws gradually from northern stations around November. And on the east coast, the rainfall amount increases in autumn and winter rather than in summer. These regional differences between west and east coasts are considered to correspond to the seasonal change of Asian summer monsoon and orographic effect. The seasonal march of rainfall in the Philippines is characterized by the sudden change of atmospheric circulation around the Philippines. Particularly, the onset and peak of rainy season on the west coast are influenced by the eastward shift of the subtropical high and the evolution of the monsoon trough with southwesterly, respectively. The increase of rainfall on the east coast is related with the weakened monsoon trough around early September. Copyright © 2006 Royal Meteorological Society [source] Application of the high-order symplectic FDTD scheme to the curved three-dimensional perfectly conducting objectsMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2007Wei Sha Abstract A high-order symplectic finite-difference time-domain (SFDTD) scheme using the diagonal split-cell model is presented to analyze electromagnetic scattering of the curved three-dimensional perfectly conducting objects. On the one hand, for the undistorted cells, the fourth-order accurate spatial difference is employed. On the other hand, for the completely distorted cells, the treatment of the curved surfaces is based on the diagonal split-cell model. Finally, for the partially distorted cells, the interpolation strategy is proposed to keep the field components continuous. The numerical experiments suggest that the diagonal SFDTD scheme can obtain more accurate results than both the staircased SFDTD scheme and the traditional diagonal FDTD method. Furthermore, in view of the high numerical stability, the improved symplectic scheme does not need to decrease time increment to comply with the stability criterion. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 931,934, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22306 [source] Reproduction in three species of rainbowfish (Melanotaeniidae) from rainforest streams in northern Queensland, AustraliaECOLOGY OF FRESHWATER FISH, Issue 2 2001B. J. Pusey Abstract , The reproductive biology of three species of rainbowfish (Melanotaeniidae) in northeastern Australian rainforest streams was investigated. Two species, Melanotaenia eachamensis and Cairnsichthys rhombosomoides are endemic to the area, whereas the third, M. splendida splendida, is more widespread. The species were all highly fecund, producing many hundreds of eggs between 1.10 and 1.24 mm in diameter. Melanotaenia eachamensis was the most fecund, produced the largest eggs of the three species, and consequently exhibited the greatest maternal investment (as measured by gonadosomatic index). The majority of reproductive effort occurred during the dry season, although reproductively active fish were present year-round for each of the species, but particularly so for M. s. splendida and C. rhombosomoides. No evidence for a role by temperature or photoperiod as environmental cues for reproduction was found, and it was suggested that gonad development was strongly tied to somatic growth. The concentration of reproduction to the dry season ensures that larvae are produced during a period of relatively stable and benign physical conditions. Comparison of temporal changes in gonadosomatic index values suggest that the spawning season of M. eachamensis, which occurs in high-elevation streams, is more restricted and commences about 1 month earlier than either other species. A similar phenology was observed for the M. s. splendida population found at high elevation and highlights the potential for spatial differences in stream productivity to influence life history., [source] A Bayesian hierarchical extreme value model for lichenometryENVIRONMETRICS, Issue 6 2006Daniel Cooley Abstract Currently, there is a tremendous scientific research effort in the area of climate change. In this paper, our motivation is to improve the understanding of historical climatic events such as the Little Ice Age (LIA), a period of relatively cold weather around 1450,1850 AD. Although the LIA is well documented in Europe, its extent and timing are not known in areas of the globe where climatological records were not kept during this period. To study the climate, which predates historical records, proxy climate records must be used. A proxy record for the timing of climatic cooling events are the ages of the moraines left behind by glacial advances. Unfortunately, to determine the ages of these moraines in alpine environments there is little material available but lichens. Hence, lichenometry was developed to determine the ages of glacial landforms by using lichen measurements. To our knowledge, this article provides the first attempt at deriving a comprehensive statistical model for lichenometry. Our model foundation is based on extreme value theory because only the largest lichens are measured in lichenometry studies. This application is novel to extreme value theory because the quantities of interest (the ages of climatic events) are not the measured quantities (lichen diameters), i.e., it is a inverse problem. We model the lichen measurements with the generalized extreme value (GEV) distribution, upon which a Bayesian hierarchical model is built. The hierarchical model enables estimation of the hidden covariate ages of the moraines. The model also allows for pooling of data from different locations and evaluation of spatial differences in lichen growth. Parameter inference is obtained using a straightforward Markov Chain Monte Carlo method. Our procedure is applied to data gathered from the Cordillera Real region in Bolivia. Copyright © 2006 John Wiley & Sons, Ltd. [source] The influence of oxygen saturation on the distributional overlap of predator (cod, Gadus morhua) and prey (herring, Clupea harengus) in the Bornholm Basin of the Baltic SeaFISHERIES OCEANOGRAPHY, Issue 1 2002Stefan Neuenfeldt Environmental heterogeneity can create boundary conditions for the co-occurrence of marine predators and their prey. If one or both are spatially constrained by their tolerance to environmental variables, then spatial differences in the availability of possible habitats define the volume of distributional overlap. Cod (Gadus morhua L.) and its prey, herring (Clupea harengus L.), in the vertically stratified Bornholm Basin of the Baltic Sea are presented as an example. A non-linear model was used to estimate oxygen avoidance thresholds for both species. Herring avoided oxygen saturation levels below 50%, while cod tolerated oxygen saturation down to 16%. The threshold of 50% oxygen saturation, below which cod could not encounter its prey, herring, was applied to a time series of vertical oxygen profiles from the centre of the Bornholm Basin to estimate the size of the overlap volume during the winter period from 1958 to 1999. Dependent on the oxygenation of the deep-water, the overlap volume varied between 57 km3 and 250 km3. [source] The influence of atmospheric circulation at different spatial scales on winter drought variability through a semi-arid climatic gradient in Northeast SpainINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 11 2006Sergio M. Vicente-Serrano Abstract This paper analyses the spatial and temporal variability of winter droughts in a semi-arid geographic gradient in Northeast Spain, from the Pyrenees in the north to the Mediterranean coastland in the south. Droughts that occurred between 1952 and 1999 were analysed by means of the Standardised Precipitation Index (SPI). The influence of the weather-type frequency and of the general North Atlantic atmospheric circulation patterns was analysed. The results indicate that winter droughts show an important spatial variability in the study area, differentiating three well-defined patterns. These correspond to the Pyrenees, the centre of the Ebro Valley, and the Mediterranean coastland. General negative trends in winter SPI have been found, which are indicative of the increase in winter drought conditions in the study area. Nevertheless, important spatial differences have also been recorded. Dominant north,south gradients in the influence of weather types are shown. Moreover, the negative trends in winter-SPI values agree with the negative trend in the frequency of the weather types prone to cause precipitation, such as the C, SW and W weather types and the increase in the frequency of A weather types. Nevertheless, in the Mediterranean coastland, the positive trend in SPI values agrees with the increase in the frequency of weather types of the east (E, SE), which are prone to cause precipitation in this area. Interannual variations in the frequency of the different weather types have been highly determined by different general atmospheric circulation patterns, mainly the North Atlantic Oscillation (NAO). Nevertheless, the correlation between the time series of weather-type frequency and the winter SPI is higher than that found between the SPI and the NAO. Thus, although the interannual NAO variability explains a high percentage of the interannual differences in the frequency of different weather types, it is not sufficient to explain the spatial and temporal variability of droughts, which respond better to atmospheric variability at more detailed (synoptic) spatial scales. Copyright © 2006 Royal Meteorological Society. [source] Increased Right Ventricular Repolarization Gradients Promote Arrhythmogenesis in a Murine Model of Brugada SyndromeJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2010CLAIRE A. MARTIN M.R.C.P. Repolarization Gradients in Brugada Syndrome.,,Introduction: Brugada syndrome (BrS) is associated with loss of Na+ channel function and increased risks of a ventricular tachycardia exacerbated by flecainide but reduced by quinidine. Previous studies in nongenetic models have implicated both altered conduction times and repolarization gradients in this arrhythmogenicity. We compared activation latencies and spatial differences in action potential recovery between different ventricular regions in a murine Scn5a+/, BrS model, and investigated the effect of flecainide and quinidine upon these. Methods and Results: Langendorff-perfused wild-type and Scn5a+/, hearts were subjected to regular pacing and a combination of programmed electrical stimulation techniques. Monophasic action potentials were recorded from the right (RV) and left ventricular (LV) epicardium and endocardium before and following flecainide (10 ,M) or quinidine (5 ,M) treatment, and activation latencies measured. Transmural repolarization gradients were then calculated from the difference between neighboring endocardial and epicardial action potential durations (APDs). Scn5a+/, hearts showed decreased RV epicardial APDs, accentuating RV, but not LV, transmural gradients. This correlated with increased arrhythmic tendencies compared with wild-type. Flecainide increased RV transmural gradients, while quinidine decreased them, in line with their respective pro- and antiarrhythmic effects. In contrast, Scna5+/, hearts showed slowed conduction times in both RV and LV, exacerbated not only by flecainide but also by quinidine, in contrast to their differing effects on arrhythmogenesis. Conclusion: We use a murine genetic model of BrS to systematically analyze LV and RV action potential kinetics for the first time. This establishes a key role for accentuated transmural gradients, specifically in the RV, in its arrhythmogenicity. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1153-1159) [source] Spatial patterns of recruitment in Mediterranean plant species: linking the fate of seeds, seedlings and saplings in heterogeneous landscapes at different scalesJOURNAL OF ECOLOGY, Issue 6 2008Lorena Gómez-Aparicio Summary 1Plant recruitment is a multiphase process that takes place in environments that are heterogeneous in space and time. In this work, I analyse how environmental heterogeneity in Mediterranean forests affects dynamics of early recruitment at different scales, using the wind-dispersed tree Acer opalus subsp. granatense as a case study. 2Seed dispersal and viability, post-dispersal predation, seedling emergence and seedling and sapling survival were evaluated in different habitats (regional scale) and microhabitats (local scale). Simultaneously, a review of the literature on spatial dynamics of plant recruitment in Mediterranean systems was conducted to look for general patterns and investigate their fit to the Acer system. Nineteen woody and herbaceous species were included in the review. 3At the regional scale, Acer recruitment dynamics strongly converged among sites of the same habitat. This was mainly due to large seedling emergence and survival differences among habitats. Although most of the studies reviewed analyzed only one site per habitat type, they also support strong regional variation (either site- or habitat-specific) in recruitment patterns. 4At the local scale, Acer recruitment was microhabitat-specific, a result shared by almost all the reviewed species independently of their life form and dispersal syndrome. This was mostly due to spatial differences in seed arrival (higher under conspecifics) and seedling survival (higher under nurse shrubs). 5Spatial discordance among seed rain and recruitment was found in 60% of the reviewed species at the regional scale, and in 67% at the local scale. Acer results supported this predominant lack of concordance. Discordance among seed rain and recruitment suggests that regeneration is largely limited by safe sites than by seed availability. Because seedling survival was the limiting process with a larger impact on the magnitude and spatial pattern of recruitment, safe sites might be defined as those where seedlings have a higher survival probability. 6Synthesis: This study indicates that the influence of seed dispersal on the spatial patterns and demography of plant species could be limited in heterogeneous and stressful environments (as are found in the Mediterranean), where recruitment is restricted to a small fraction of the landscape. If we are to preserve the distribution and abundance of Mediterranean species in the face of environmental changes, we need to explicitly consider the strong patch-specificity that characterizes their recruitment process at all scales. [source] MIND THE GAP: UNEMPLOYMENT IN THE NEW EU REGIONSJOURNAL OF ECONOMIC SURVEYS, Issue 1 2008Anna Maria Ferragina Abstract The paper surveys the theoretical and empirical literature on regional unemployment during transition in Central and Eastern Europe. The focus is on optimal speed of transition (OST) models and on comparison of them with the neo-classical tradition. In the typical neo-classical models, spatial differences essentially arise as a consequence of supply side constraints and institutional rigidities. Slow-growth, high-unemployment regions are those with backward economic structures and constraints on factors mobility contribute to making differences persistent. However, such explanations leave the question unanswered of how unemployment differences arise in the first place. Economic transition provides an excellent testing ground to answer this question. Pre-figuring an empirical law, the OST literature finds that the high degree of labour turnover of high unemployment regions is associated with a high rate of industrial restructuring and, consequently, that low unemployment may be achieved by implementing transition more gradually. Moreover, international trade, foreign direct investment and various agglomeration factors help explain the success of capital cities compared to peripheral towns and rural areas in achieving low unemployment. The evidence of the empirical literature on supply side factors suggests that wage flexibility in Central and Eastern Europe is not lower than in other EU countries, while labour mobility seems to reinforce rather than change the spatial pattern of unemployment. [source] Spatially heterogeneous stochasticity and the adaptive diversification of dormancyJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 10 2009E. Rajon Abstract Diversified bet-hedging, a strategy that leads several individuals with the same genotype to express distinct phenotypes in a given generation, is now well established as a common evolutionary response to environmental stochasticity. Life-history traits defined as diversified bet-hedging (e.g. germination or diapause strategies) display marked differences between populations in spatial proximity. In order to find out whether such differences can be explained by local adaptations to spatially heterogeneous environmental stochasticity, we explored the evolution of bet-hedging dormancy strategies in a metapopulation using a two-patch model with patch differences in stochastic juvenile survival. We found that spatial differences in the level of environmental stochasticity, restricted dispersal, increased fragmentation and intermediate survival during dormancy all favour the adaptive diversification of bet-hedging dormancy strategies. Density dependency also plays a major role in the diversification of dormancy strategies because: (i) it may interact locally with environmental stochasticity and amplify its effects; however, (ii) it can also generate chaotic population dynamics that may impede diversification. Our work proposes new hypotheses to explain the spatial patterns of bet-hedging strategies that we hope will encourage new empirical studies of this topic. [source] Spatial interpolation of GPS integrated water vapour measurements made in the Swiss AlpsMETEOROLOGICAL APPLICATIONS, Issue 1 2007June Morland Abstract The 31 stations in the Swiss GPS network are located at altitudes between 330 and 3584 m and have provided hourly Integrated Water Vapour (IWV) measurements since November 2000. A correction based on an exponential relationship is proposed for the decrease in IWV with altitude. The scale height depends on the ratio of IWV measured at Jungfraujoch (3584 m) to that measured at Payerne (498 m). An additional coefficient, dependent on the east-west and north-south spatial differences in the IWV, improves the fit to the data. The IWV at heights between 750 and 3500 m was estimated from GPS measurements at Payerne and compared with the Payerne radiosounding. The altitude correction introduced an additional bias of 0.2 to 0.4 mm between GPS and radiosonde. The IWV was normalized to 500 m and the increases and decreases due to the passage of a series of frontal systems between 11 and 14 January 2004 were mapped. A four-year climatology of IWV normalized to 500 m showed that the Alpine stations are more moist in spring, summer and autumn than the stations in the Swiss plains to the north of the Alps. This was attributed to more moist Mediterranean air being blocked by the Alps. Copyright © 2007 Royal Meteorological Society [source] Calcium requirement for ethylene-dependent responses involving 1-aminocyclopropane-1-carboxylic acid oxidase in radicle tissues of germinated pea seeds,PLANT CELL & ENVIRONMENT, Issue 5 2003L. PETRUZZELLI ABSTRACT The Ca2+ requirements of ethylene-dependent responses were investigated in germinating seeds of Pisum sativum L. using 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (Ps-ACO1), ACC synthase (Ps-ACS2) and class I , -1,3-glucanase as molecular markers. Ethylene biosynthesis and responsiveness are localized to the elongation and differentiation zones of the pea radicle. Ethylene treatment induced ectopic root hair formation in the cell elongation zone and promoted root hair elongation growth in the radicles of germinated seeds. Characterized Ca2+ antagonists, including EGTA, lanthanum, verapamil, ruthenium red, W-7, lithium and neomycin, were used to test for the involvement of the apoplastic and the intracellular Ca2+ -pool, the Ca2+/calmodulin complex and the phoshoinositide (PI) cycle in the ethylene responses. Ca2+ release from internal pools, but no appreciabe apoplastic Ca2+, is involved in the transcriptional induction by ethylene of Ps-ACO1 and in ectopic root hair formation in the radicle elongation zone of germinated pea seeds. Furthermore, the Ca2+/calmodulin complex and the PI cycle seem to be involved in these ethylene responses. In contrast, both the intracellular and the apoplastic Ca2+ -pools are required for the negative and positive ethylene responses to the gene expression of PS-ACS2 and class I , -1,3-glucanase, respectively; and, apoplastic Ca2+ also promotes root hair elongation growth. Tissues from adult plants and germinating seeds exhibit temporal and spatial differences in the signal/response coupling by Ca2+ of ethylene-regulated processes. [source] Native Australian frogs avoid the scent of invasive cane toadsAUSTRAL ECOLOGY, Issue 1 2009LÍGIA PIZZATTO Abstract Invasive species can affect the ecosystems they colonize by modifying the behaviour of native taxa; for example, avoidance of chemical cues from the invader may modify habitat use (shelter site selection) by native species. In laboratory trials, we show that metamorphs of most (but not all) native frog species on a tropical Australian floodplain avoid the scent of invasive cane toads (Bufo marinus Linnaeus 1758). Cane toads also avoid conspecific scent. This response might reduce vulnerability of metamorph frogs and toads to larger predatory toads. However, similar avoidance of one type of pungency control (garlic), and the presence of this avoidance behaviour in frogs at the toad invasion front (and hence, with no prior exposure to toads), suggest that this may not be an evolved toad-specific response. Instead, our data support the simpler hypothesis that the metamorph anurans tend to avoid shelter sites that contain strong and unfamiliar scents. Temporal and spatial differences in activity of frogs versus toads, plus the abundance of suitable retreat sites during the wet season (the primary time of frog activity), suggest that avoiding toad scent will have only a minor impact on the behaviour of native frogs. However, this behavioural impact may be important when environmental conditions bring toads and frogs into closer contact. [source] Disease Mapping of Stage-Specific Cancer Incidence DataBIOMETRICS, Issue 3 2002Leonhard Knorr-Held Summary. We propose two approaches for the spatial analysis of cancer incidence data with additional information on the stage of the disease at time of diagnosis. The two formulations are extensions of commonly used models for multicategorical response data on an ordinal scale. We include spatial and age-group effects in both formulations, which we estimate in a nonparametric smooth way. More specifically, we adopt a fully Bayesian approach based on Gaussian pairwise difference priors where additional smoothing parameters are treated as unknown as well. We argue that the methods are useful in monitoring the effectiveness of mass cancer screening and illustrate this through an application to data on cervical cancer in the former German Democratic Republic. The results suggest that there are large spatial differences in the stage proportions, which indicate spatial variability with respect to the introduction and effectiveness of Pap smear screening programs. [source] Reproductive Phenology of a Tropical Canopy Tree, Spondias mombin,BIOTROPICA, Issue 4a 2000Gregory H. Adler ABSTRACT We studied the reproductive phenology of isolated populations of Spondias mombin to determine the degree of flowering and fruiting synchrony among populations and to examine spatial and temporal variability in fruit production. The study was conducted on six small islands (1.8,3.5 ha) in the Panama Canal. All individuals (10 cm in diameter at breast height (DBH) were marked in 1991 and censused each year through 1994 to record recruits and deaths. All marked trees were censused monthly for flowering and fruiting activity from April 1992 through December 1995. Spondias mombin was seasonal and highly synchronous in flower and fruit production among islands and across years. Proportions of individuals fruiting varied among islands, years, and tree size classes. There was a positive relationship between probability of fruit production and tree size. Synchronous reproductive activity in S. mombin probably was due to responses to proximate environmental cues such as fluctuations in irradiance, but other factors must have been responsible for temporal and spatial variation in reproductive performance. We suggest that this variation may have been due partly to temporal and spatial differences in pollinator abundance. [source] | ||||||||||||||||||||||||||||