Clearing

The forest buffalo (Syncerus caffer nanus) typically inhabits the dense rain forests of western and central Africa. We recorded the 1st data on the behavior and social interactions of forest buffalo in natural forest clearings that represent crucial places in the rain forest for feeding and social interactions among individuals. Data were collected from a buffalo herd during January 2002-January 2004 in the Bai-Hokou study area (Dzanga-Ndoki National Park, Central African Republic). We analyzed typical behaviors (i.e., grazing, resting or ruminating, and moving) of both the herd and individuals (from 16 to 24 buffalos), as well as the most frequent social interactions. Spatial distribution among buffalos in the herd, related to both distance from forest edge and to the season (wet versus dry seasons), showed that the adult male was commonly closer to the females than to juveniles. Individuals were generally further away from each other when in the vicinity of the forest edge. Moreover, at greater distances from the forest edge, the number of buffalos in the herd increased. During the wet season, the herd was generally smaller and individuals were more spread out within the same clearing. The most common behavior of the male, females, and juveniles was resting or ruminating. Behavioral interactions by adults were mainly addressed to juveniles.

The presence of abundant charcoal in sedimentary deposits is one of the key indicators of early Maori presence in New Zealand. However, it is often difficult to distinguish natural fire from anthropogenic. Studies of sedimentary charcoal and pollen in the Tarahoka clearing (or waerenga) in Waipoua Forest, where intentional burning is supported by the oral history of Te Iwi O Te Roroa, were undertaken with the belief that they would provide a level of detail, which could aid interpretation elsewhere. Vegetation plots and dendrochronological studies of trees on the clearing margins date the cessation of burning and subsequent invasion by woody plants. The radiocarbon and palynological results indicate that the clearing was created by fire ca. AD 1460. Although people were probably present to windward in the Waipoua valley before this time, they left no palynological signature at the study site. The date for the formation of the clearing agrees with others indicating population increase at this time, and with oral tradition for the arrival in the Waipoua valley of Manumanu 1, the ancestor of Te Iwi O Te Roroa. The maintenance of the clearing in seral vegetation by fire for >300 years supports the tradition that it was used as a kiwi (Apterix australis) hunting site. During the period of European contact, fire intensity appears to have declined, while fire frequency may have increased, favouring the spread of bracken (rahurahu, Pteridium esculentum), an important food source. Intentional firing probably ceased ca. 1900, by which time the local Maori population was in decline and European gum-diggers were camped in the clearing. The postulated sequence of formation, use and abandonment of the clearing requires confirmation by investigation of similar nearby sites using the same combination of methods.

Abstract:" Balancing Cooperation and Competition in Retail Payment Systems: Lessons from Latin America Case Studies" presents the findings of four case studies in Latin America (Argentina, Brazil, Colombia and Mexico) that have explored the issue of cooperation and ...

We consider M/G/1-type queueing systems with 'disasters', occurring at certain random times and causing an instantaneous removal of the entire residual workload from the system. After such a clearing, the system is assumed to be ready to start working again immediately. We consider clearings at deterministic equidistant times, at random times and at crossings of some prespecified level, and derive the stationary distribution of the workload process for these clearing times and some of their combinations.

This paper analyses the influence of temperature changes on load transmission between floor slabs and shores during the in situ casting of concrete slabs by the shoring-clearing-striking method. Therefore several experimental studies were carried out which measured both the internal temperature evolution of the slabs and the loads on the shores. With the results of these studies, a Finite Element Model (FEM) of an experimental structure was then developed. In both the FEM and the experimental studies the same behaviour was observed regarding changes in temperature. When temperatures rose, the loads on shores decreased, accompanied by a reduction in slab deflection. When temperatures dropped, the loads on the shores increased, accompanied by an increased slab deflection. In the experimental study, for a temperature increment of ±1°C the load per surface unit on shores varied between 0.13 kN/m 2 and 0.34 kN/m 2 , which represents between 2% and 6% of the self-weight of the slabs. The main cause of these load variations appears to be the temperature gradient inside the floor slabs.

Résumé/Abstract Parmi les différents modèles proposés pour l'agriculture préhistorique, il existe celui des terres défrichées ou culture temporaire dans la forêt après avoir coupé et brûlé la végétation. Pour cet article des recherches ont été faites dans les terres ...

In order to identify marker lines expressing GUS in various endosperm compartments and at different developmental stages, a collection of Arabidopsis thaliana (L.) Heynh. promoter trap lines were screened. The screen identi®ed 16 lines displaying GUS-reporter gene expression in the endosperm, embryo and other seed organs. The distinctive patterns of GUS expression in these lines provide molecular markers for most cell compartments in the endosperm of Arabidopsis seeds at all developmental stages, and represent a valuable research tool for characterizing present and future Arabidopsis seed mutants. GUS expression patterns of these 16 lines are presented here. One line showed chalazal endosperm-speci®c GUS activity at the heart stage of embryo development. In six lines embryo-speci®c GUS activity was detected. Six lines exhibited GUS activity predominantly in the endosperm and embryo while two lines showed strong GUS activity in all seed organs. In one line GUS activity was detected in integuments and syncytial endosperm, while the GUS activity at the cotyledonary stage of the embryo was seed coat-speci®c. In addition, two funiculus markers and two silique markers expressed in the abscission zone and the guard cells are also presented.

In blast engineering, many designs begin with simplified hand procedures with the loading parameters determined based upon a reflective surface of infinite size. Individual structural members such as columns have finite widths and should be considered as finite surfaces for blast loading calculations. A study was performed to investigate the effect of finite flange width on blast loadings on structural components. The diffraction of a blast wave around the leading edges of the cross section and the propagation of rarefaction waves from the leading edges to the column centerline leads to a more rapid reduction in reflected pressure than that of an infinite surface: a process that is widely known as clearing. A series of analyses were performed using the computational fluid dynamics code Air3d. Peak reflected pressures are not changed by the "finiteness" of the section, although the reflected impulse can be substantially reduced by clearing. For a given charge mass, held constant for a range of stand-off distances, R, impulse is approximately proportional to 1 / R when considering an infinite surface. If clearing is considered, the reflected impulse is still proportional to 1 / R, but can be 50% lower than the value computed for an infinite surface, which has significant implications for blast resistant design of structural components.

Travertines are carbonate deposits formed generally during temperate climatic periods. They usually present a succession of travertinous units and detrital sedimentary levels containing leaf impressions and charcoal, respectively. The travertine of St-Antonin was formed during the Holocence in accordance with this model; snail shells and archaeological material have also been preserved, essentially in detrital levels. An interdisciplinary investigation combining two palaeobotanical approaches (identi cation of leaf imprints and charred wood) has been carried out to identify vegetation changes, at a local or microregional scale during the travertine formation. Our results were compared with those of previous malacological, geomorphological and archaeological studies. The Preboreal and Boreal sequence of the travertine shows evidence of a reduction of the riverside vegetation correlated with the establishment of a mesophilous vegetation dominated by the pubescent oak (Quercus pubescens). During the Boreal-Atlantic transition, the vegetation structure changed slightly under anthropogenic in uence. From the Atlantic to the rst part of the Subboreal, vegetation seems to have been profoundly affected by intensive human exploitation. This process has broken up the forested area into different plant communities and favoured the dominance of heliophilous and thermophilous species.

Republic of Uzbekistan produces more than 3000000 tons of cotton per year, 800000 tons of this harvest is a high quality fiber which is exported to abroad. One of good reason, and global task of production high quality fiber, it is value and request from other countries. A main point of taking high quality fiber depends on previous cultivation.

Toxoplasma gondii is an obligate, intracellular parasite with a broad host range, including humans and rodents. In both humans and rodents, Toxoplasma establishes a lifelong persistent infection in the brain. While this brain infection is asymptomatic in most immunocompetent people, in the developing fetus or immunocompromised individuals such as acquired immune deficiency syndrome (AIDS) patients, this predilection for and persistence in the brain can lead to devastating neurologic disease. Thus, it is clear that the brain-Toxoplasma interaction is critical to the symptomatic disease produced by Toxoplasma, yet we have little understanding of the cellular or molecular interaction between cells of the central nervous system (CNS) and the parasite. In the mouse model of CNS toxoplasmosis it has been known for over 30 years that neurons are the cells in which the parasite persists, but little information is available about which part of the neuron is generally infected (soma, dendrite, axon) and if this cellular relationship changes between strains. In part, this lack is secondary to the difficulty of imaging and visualizing whole infected neurons from an animal. Such images would typically require serial sectioning and stitching of tissue imaged by electron microscopy or confocal microscopy after immunostaining. By combining several techniques, the method described here enables the use of thick sections (160 µm) to identify and image whole cells that contain cysts, allowing three-dimensional visualization and analysis of individual, chronically infected neurons without the need for immunostaining, electron microscopy, or serial sectioning and stitching. Using this technique, we can begin to understand the cellular relationship between the parasite and the infected neuron.

This paper presents Artificial Neural Network based critical clearing time (CCT) calculation for IEEE-9 bus system. The critical clearing time (CCT) at the critical contingency is considered as an index for transient stability. By selecting loads and generators active and reactive power as a input neurons critical clearing time is determined. The modeling and simulation results for load flow and CCT calculations are accomplished using the simulation package ETAP. The ANN training and testing is implemented in MATLAB software

In blast engineering, many designs begin with simplified hand procedures with the loading parameters determined based upon a reflective surface of infinite size. Individual structural members such as columns have finite widths and should be considered as finite surfaces for blast loading calculations. A study was performed to investigate the effect of finite flange width on blast loadings on structural components. The diffraction of a blast wave around the leading edges of the cross section and the propagation of rarefaction waves from the leading edges to the column centerline leads to a more rapid reduction in reflected pressure than that of an infinite surface: a process that is widely known as clearing. A series of analyses were performed using the computational fluid dynamics code Air3d. Peak reflected pressures are not changed by the "finiteness" of the section, although the reflected impulse can be substantially reduced by clearing. For a given charge mass, held constant for a range of stand-off distances, R, impulse is approximately proportional to 1 / R when considering an infinite surface. If clearing is considered, the reflected impulse is still proportional to 1 / R, but can be 50% lower than the value computed for an infinite surface, which has significant implications for blast resistant design of structural components.

Resolving disputes resulting from high speed and fast-moving financial transactions has become an essential requirement for the stability of global financial markets as proven by previous crises. In the 2007 crisis, millions of investors ended with worthless investment agreements. The public did not believe they could pursue claims in state courts and had no faith in the operating regulatory systems. Delays in the enforcement of compensatory awards drained the concept of justice of its meaning. Bankers were bailed out instead of being made to pay for acts of recklessness, information asymmetry and mis-selling. The result was panic and a run on investment banks and the financial crisis ensued. The question is whether an arbitration process that guarantees immediate payment of arbitral awards can accelerate recovery from a crisis and alleviate the burden on state bailouts using taxpayers’ money? Empirical research show that enforceable and swift dispute resolution for financial disput...

It is somewhat known that poetry occupies a privileged place in Heideggerian philosophy. Though as Heidegger himself saw, its proximity to thought is framed by a subtle difference which is not easy to discover. This relation is often seen as a mixture. The present text aims to elucidate central aspects which will allow for a better understanding of the nearness of philosophizing and poeticizing. The author's aim is to clarify elements which make it possible to comprehend this closeness, with a starting point of understanding the difference between poetry (Dichtung) and Clearing (Lichtung). Since these conclusions are drawn from a late-Heidegger perspective, the author begins by offering an exposition of the historical perspective of Being, and more precisely, of the contemporary technical epoch.

Despite a lot of re-structuring and many innovations in recent years, the securities transaction industry in the European Union is still a highly inefficient and inconsistently configured system for cross-border transactions. This paper analyzes the functions performed, the institutions involved and the parameters concerned that shape market and ownership structure in the industry. Of particular interest are microeconomic incentives of the main players that can be in contradiction to social welfare. We develop a framework and analyze three consistent systems for the securities transaction industry in the EU that offer superior efficiency than the current, inefficient arrangement. Some policy advice is given to select the ’best ’ system for the Single European Financial Market. JEL Classification: F 36, G 28, G 34, L22, P 51

Local sharing is a method designed for efficient multimodal optimisation that combines fitness sharing with spatially-structured populations and elitist replacement. In local sharing, the bias toward sharing and the influence of spatial structure is controlled by the deme (neighbourhood) size. This introduces an undesirable trade-off; to maximise the sharing effect, large deme sizes must be used, but the opposite must be true if one wishes to maximise the influence of spatial population structure. This paper introduces two modifications to the local sharing method. The first alters local sharing so that parent selection and fitness sharing operate at two different spatial levels; parent selection is performed within small demes, while the effect of fitness sharing is weighted according to the distance between individuals in the entire population structure. The second method replaces fitness sharing within demes with clearing to produce a method that we call local clearing. The proposed methods, as tested on several benchmark problems, demonstrate a level of efficiency that surpasses that of traditional fitness sharing and standard local sharing. Additionally, they offer a level of parameter robustness that surpasses other elitist niching methods, such as clearing. Through analysis of the local clearing method, we show that this parameter robustness is a result of the isolated nature of the demes in a spatially-structured population being able to independently concentrate on subsets of the desired optima in a fitness landscape.

The fish communities of mangrove and cleared sites were investigated in Gazi Bay, Kenya. Five forested sites were compared with paired sites that had been cleared of mangroves by human activity. Forested sites included plantations and natural stands of Sonneratia alba and natural Rhizophora mucronata stands. Two methods of stake netting were used to take quantitative samples; method one used a single 100-m-long, 18-mm mesh net, method two used paired 24-m-long, 1-mm mesh netsdsamples were taken during seven different months in 2002. Mean abundances of fish found in mangrove and cleared sites, respectively, were 0.004 m ÿ2 and 0.014 m ÿ2 (method 1) and 0.21 m ÿ2 and 0.25 m ÿ2 (method 2). Thirty species were sampled, 12 of which were found exclusively in mangrove habitats and 10 of which were limited to cleared sites. The most abundant species in mangrove plots was Atherina afra (although it was only found in two, large catches); the most abundant in cleared plots was Gerres oyena (found frequently). Mean abundance (using data pooled for all sites) was significantly higher in cleared, compared with forested, sites, and multivariate analysis showed significantly different community structures in the two habitat types. There was large variation in catch rates between dates and sites, with one forested site recording no catches at all. These results do not support the predator refuge hypothesis (which predicts higher abundance of juvenile fish inside mangroves). The low abundance of fish recorded in the mangrove sites may have been due to site-specific factors determining fish abundance within mangrove forests, to the sampling techniques used or to relatively high turbidities at these sites.

Accounting of carbon stocks in woody vegetation for greenhouse purposes requires definition of medium term trends with accurate error assessment. Tree and shrub cover was sampled through time at randomly located sites over a large area of central Queensland, Australia using aerial photography from 1945 to 1999. Calibration models developed from field data for the same land types as those represented within the study area allowed for the extrapolation of overstorey and understorey cover, basal area and biomass values and these were modelled as trends over the latter half of the 20th century. These structural attributes have declined over the region because of land clearing with values for biomass changing from a mean of 58.0(^1.2) t/ha in 1953 to 41.1(^1.0) t/ha in 1991. The biomass of Acacia on clay and Eucalypt on texture contrast soils land types has declined most dramatically. Within uncleared vegetation there was an overall trend of increase from 56.1(^1.2) t/ha in 1951 to 67.6(^1.3) t/ha in 1995. The increase in structural attributes within uncleared vegetation was most pronounced for the Eucalypt on texture contrast soils and Eucalypt on clay land types. It was demonstrated that the sites sampled were representative of their land types and that spatial bias of the photography, undetected tree-killing, sampling error, inherent variability of structural attributes and measurement error should not have impacted greatly on bias or precision of trend estimates for well-sampled land types. Certainly the errors are not likely to be substantial for trends averaged over all land types and they provide an accurate assessment of the magnitude and direction of change. The technique presented here would appear to be a robust means of accounting for the above-ground woody component of woodlands and open forests and will also contribute to a broader understanding of savanna dynamics. q

Honduras or bigleaf mahogany (Swietenia macrophylla King) is the most commercially important timber species in the Neotropics, but it often does not regenerate successfully after harvesting. Effective methods are needed to sustain or increase mahogany yields by increasing regeneration. This study evaluates the effects of three treatments (slash, fell and burn; slash, fell and leave; and uprooting and pushing away trees using machines) used to open 0.5 ha clearings, plus a control under the forest canopy, and two sowing methods (surface-sown seed and buried seed) on the germination, establishment, survival, and early growth of mahogany. After 10 months, significantly more buried seeds yielded established seedlings (20%) than surface-sown seeds (9%), but there were no significant differences among clearing treatments. Establishment on controls averaged 18%.

The western lowland gorilla (Gorilla gorilla gorilla) is one of the most sexually dimorphic primate species. Mature males are twice the size of females and have grey fur on their backs and a fibrous, adipose Grant sponsors: Espèces-Phares program (DG Environnement,

... Auteur(s) / Author(s). ERNY-RODMANN C. (1) ; GROSS-KLEE E. (2) ; HAAS JN (3) ; JACOMET S. (1) ; ZOLLER H. (1) ; ... Résumé / Abstract. Autrefois, on considérait que l'installation des premiers villages sur les rives des lacs marquait le début du processus de néolithisation. ...

It is somewhat known that poetry occupies a privileged place in Heideggerian philosophy. Though as Heidegger himself saw, its proximity to thought is framed by a subtle difference which is not easy to discover. This relation is often seen as a mixture. The present text aims to elucidate central aspects which will allow for a better understanding of the nearness of philosophizing and poeticizing. The author's aim is to clarify elements which make it possible to comprehend this closeness, with a starting point of understanding the difference between poetry (Dichtung) and Clearing (Lichtung). Since these conclusions are drawn from a late-Heidegger perspective, the author begins by offering an exposition of the historical perspective of Being, and more precisely, of the contemporary technical epoch.

ABSTRACT Abstract The dry sclerophyll forest community of the Tomago Sandbeds, near Newcastle in New South Wales, has been subject to regular disturbances due to fire, clearing and strip mining for over 18 years. In this study we use chronosequence analysis to examine whether the structure of the ant community varies with the type of disturbance and the time since disturbance. We treat the recovery trajectory after fire as a control trajectory because fire is an endogenous disturbance. The main analyses were based on an ant fauna comprising 72 species sampled from 44 sites surveyed in December 1992. Comparison with samples taken in April and December 1991, and for cumulative records for all sites over this 20 month period, all show quantitatively similar responses. Results suggest that while fire has a minor effect on the composition of the ant community over time, the impact of clearing and mining is much more severe. Ant species richness at cleared and mined sites recovers rapidly, overshoots controls in mid-succession and returns to control levels by 18 years after disturbance. The cumulative number of species recorded over all sites (from the total recorded fauna of 82 species) for each different disturbance type were: burned, 61; cleared, 55; and mined 56. Species composition at cleared or mined sites, after 18 years, approaches but does not match controls. The recovery trend for mined sites lags slightly behind that for cleared sites, which have reached 49% similarity with the oldest burned sites, while mined sites have not exceeded 39% similarity of species composition. The main patterns in the ant community appear to be related to habitat variables. These results provide further evidence that the ant community may be used as a reliable bio-indicator for evaluating the extent of habitat damage and recovery after disturbance in these Australian forests.

The aim of this study was to evaluate both the precision of filling and the extension of voids in main root canals as well as filling of lateral canals after using a two-phase filling technique with two sealers. Twenty-four maxillary and 26 mandibular molars were selected and randomly assigned to two groups. Root canals were instrumented and then filled using the vertical compaction with the apical backfilling technique, with Pulp Canal Sealer (EWT) in group "A" and AH Plus in group "B." After clearing, voids within the filled main canals were measured by using a stereomicroscope. In addition, visible lateral canals were counted, each unfilled space was measured, and five ratings (0-4) were fixed. In both groups, in the most apical 4 mm of main canals, where gutta-percha was cold compacted, lesser voids (p <or= 0.05) were found than in the middle-coronal thirds backfilled with thermomechanical compaction. In group "B," more precision (p <or= 0.05)...

Aims of this work were to examine lateral canals in extracted teeth, to propose a new technique to produce artificial lateral canals, and to compare two obturation techniques. Cleared roots were examined to record measure and shape of lateral canals. Artificial lateral canals were prepared on human demineralized teeth before final clearing. Specimens were divided in two groups: canals of group 1 were filled with Schilder's technique, canals of group 2 were filled with vertical compaction with apical backfilling. Stereomicroscopic analysis of lateral canal filling revealed lower filling rates in apical canals compared to coronal ones and higher filling rates with "vertical compaction with apical backfilling" compared to Schilder's group. The tested procedure appears to be a reliable technique to obtain standardized lateral canals and to compare filling procedures.

This special issue of Interfaces is devoted to the finalists of the 36th annual competition for the Franz Edelman Award for Achievement in Operations Research and the Management Sciences, the profession's prestigious award for the practice of operations research. Brian Denton, chair of the competition, and ManMohan S. Sodhi, editor of this special issue, provide an overview of the competition and introduce the finalists.

Die Dokumente auf EconStor dürfen zu eigenen wissenschaftlichen Zwecken und zum Privatgebrauch gespeichert und kopiert werden. Sie dürfen die Dokumente nicht für öffentliche oder kommerzielle Zwecke vervielfältigen, öffentlich ausstellen, öffentlich zugänglich machen, vertreiben oder anderweitig nutzen. Sofern die Verfasser die Dokumente unter Open-Content-Lizenzen (insbesondere CC-Lizenzen) zur Verfügung gestellt haben sollten, gelten abweichend von diesen Nutzungsbedingungen die in der dort genannten Lizenz gewährten Nutzungsrechte. Terms of use: Documents in EconStor may be saved and copied for your personal and scholarly purposes. You are not to copy documents for public or commercial purposes, to exhibit the documents publicly, to make them publicly available on the internet, or to distribute or otherwise use the documents in public.

To mimic catastrophic disturbances which have favored the establishment of natural stands rich in mahogany (Swietenia macrophylla), two 5000 m 2 clearings were established in each of four locations using each of three treatments: complete felling; slashing, felling and burning; and machine-clearing, which uprooted all prior vegetation. One to three months later, and again after an additional 12 months, twenty 4-month-old mahogany seedlings were planted in the center of each clearing, and, simultaneously, nearby, under the forest canopy. One year after the first planting and again 7 months later, vines and competing vegetation were cleaned from around the seedlings on one of each type of clearing in each location. Fifty-eight months later, only 5% of mahogany seedlings survived under the canopy, as compared to 32% on felled clearings and 50% on burned or machine-made clearings. Average annual growth of seedlings planted the year clearings were opened was approximately double that of seedlings planted a year later, after natural regeneration of other species had become established. At 58 months uncleaned trees averaged 352 cm in height (and the tallest 600 cm) on burned clearings, 324 cm on machine-made clearings, and 195 cm on felled clearings. Surviving seedlings planted under the forest canopy had grown less than 30 cm during the same period. On burned and machine-made clearings the effect of cleaning on growth was not statistically significant, but on felled clearings cleaning increased growth by 120%, to rates similar to those on burned clearings. Attack by the Hypsipyla grandella shootborer was significantly affected by cleaning. After 58 months, only 12% of seedlings on uncleaned plots had been attacked, compared to 44% of seedlings on cleaned plots. Cleaning also significantly increased vines, particularly on seedlings planted the year after clearings were created: 36% of all seedlings on cleaned plots had vines, as compared to 19% of uncleaned seedlings. In summary, planting mahogany seedlings under the forest canopy cannot be expected to regenerate mahogany trees. However, mahogany seedlings survive and grow well on clearings, with no subsequent interventions, if planted shortly after these are opened by machine or burning. This approach to regeneration could be expected to yield densities of 100 commercialsized mahogany trees/ha among a matrix of 400 naturally regenerated trees/ha of other species. At this rate, regenerating mahogany on clearings equivalent to 3% of the annual cutting area intervened at each harvest, could provide for replacement of mahogany trees harvested from the permanent forest reserves in the region.

Many predict that innovations in retail payment may render cash obsolete. We investigate this possibility in the context of recent payment innovations such as contactless-credit and stored-value cards. We apply causal inference methods on the 2009 Bank of Canada Method of Payment survey, a representative sample of adult Canadians' shopping behaviour for retail consumption over a three-day period. We find that using contactless credit cards and stored-value cards lead to a reduction in average cash usage for transactions both in terms of value and volume. Sensitivity analysis is undertaken and our estimates are robust to hidden bias.

Honduras or bigleaf mahogany (Swietenia macrophylla King) is the most commercially important timber species in the Neotropics, but it often does not regenerate successfully after harvesting. Effective methods are needed to sustain or increase mahogany yields by increasing regeneration. This study evaluates the effects of three treatments (slash, fell and burn; slash, fell and leave; and uprooting and pushing away trees using machines) used to open 0.5 ha clearings, plus a control under the forest canopy, and two sowing methods (surface-sown seed and buried seed) on the germination, establishment, survival, and early growth of mahogany. After 10 months, significantly more buried seeds yielded established seedlings (20%) than surface-sown seeds (9%), but there were no significant differences among clearing treatments. Establishment on controls averaged 18%.

Aims of this work were to examine lateral canals in extracted teeth, to propose a new technique to produce artificial lateral canals, and to compare two obturation techniques. Cleared roots were examined to record measure and shape of lateral canals. Artificial lateral canals were prepared on human demineralized teeth before final clearing. Specimens were divided in two groups: canals of group 1 were filled with Schilder's technique, canals of group 2 were filled with vertical compaction with apical backfilling. Stereomicroscopic analysis of lateral canal filling revealed lower filling rates in apical canals compared to coronal ones and higher filling rates with "vertical compaction with apical backfilling" compared to Schilder's group. The tested procedure appears to be a reliable technique to obtain standardized lateral canals and to compare filling procedures.