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A paradoxical situation was found in the sand filters of a cold marine mesocosm: meiofaunal masses which were large enough to inhibit the mineralization and nitrification processes coexisted with nitrogen cycling bacteria. To test whether the copepod-dominated meiofauna were resident and actively feeding or transient and carried passively through the sand filters, residence times (RTs) were measured for various meiofaunal groups in a newly started filter and in a long established one. Most meiofauna colonized the newly started filter in less than 6 h, but their RTs were less than 24 h. In contrast, RTs were 147d for halacarids, 291 d for harpacticoid copepods and 1228d for nematodes in the long established filter. Mesocosm periphyton. which occupied a large fraction of the mesocosm surface area and was characterized by high meiofaunal densities, was probably the main source of meiofauna in the sand filters. Pool sediments, consisting of gravel or sand, were second to periphyton and contributed hydrozoans and mesopsammic species to the filters. The small copepod Pseudonychocamptus proximus progressively replaced the large Tisbe furcata in sand filters during the fall of 1995 and was responsible for the large increase in meiofaunal biomass observed after spring 1996. This replacement was presumably facilitated by the copepod size selection process operated by the filters. Large copepods were retained by the surface layer of sand or brought up by the backwash water and then exit the mesocosm through the drain. High meiofaunal populations did not significantly affect nitrogen cycling bacteria in sand filters probably because meiofauna also fed on other abundant food sources which were carried in by the water flow.

Recovery from exercise is associated with significant cardiovascular adjustments. Studies have shown that a single bout of dynamic exercise elicits a persistent reduction in mean arterial pressure lasting nearly 2 h in healthy normotensive individuals (Halliwill, 2001). It occurs in response to either aerobic or resistance exercise (MacDonald et al. 1999) although the magnitude of the decrease in mean arterial pressure is more pronounced and longer following exercise of increasing intensity (Forjaz et al. 2004). The removal of the skeletal muscle pump is thought to promote venous blood pooling which in turn reduces cardiac filling and unloads cardiopulmonary baroreceptors (Halliwill, 2001). The baroreflex is reset to defend a lower blood pressure following exercise and sympathetic vasoconstrictor outflow is consequently reduced (Halliwill et al. 1996). Furthermore, vascular responsiveness to sympathetic vasoconstrictor outflow is impaired so that vascular resistance is attenuated for a given level of sympathetic nerve stimuli (Halliwill et al. 2003). Other factors contributing to the post-exercise hyperaemia include a sustained histamine receptor-dependent vasodilatation (McCord & Halliwill, 2006). The vasodilatation that underlies post-exercise hypotension is not restricted to active skeletal muscles but also involves inactive muscle regions as forearm and calf vascular resistances are decreased in parallel with systemic vascular resistance (Senitko et al. 2002). Recent interpretation of data suggests that post-exercise hypotension in healthy sedentary and normally active individuals is due to a persistent rise in systemic vascular conductance that is not completely offset by increases in cardiac output (Halliwill, 2001). However, endurance-trained men appear to be an exception as systemic vascular conductance remains unchanged or decreases relative to pre-exercise and cardiac output falls during recovery from exercise (Senitko et al. 2002; Dujic et al. 2006). Differences in myocardial contractility and/or central venous pressure (associated with sweating-induced plasma volume losses) response have been proposed as possible factors underlining the post-exercise reduction in cardiac output. Lynn et al. (2009) demonstrate in this issue of The Journal of Physiology that ‘in the absence of either superimposed orthostatic stress or hypervolaemia, oral fluid replacement that restores normal plasma volume does not attenuate post-exercise hypotension’ but does mitigate the reduction in cardiac output (and stroke volume) typically seen in endurance-trained individuals. While it is suggested that factors related to plasma volume changes that affect preload and/or cardiac dimension and function may explain the underlying cause for the reduced cardiac output observed post-exercise in endurance-trained men, Lynn et al. (2009) propose a novel perspective that the cause may be of thermal rather non-thermal origin. An unexpected finding of their study was the observed similarity in the pattern of response in cardiac output following exercise performed in the heat without fluid replacement compared to exercise at normal ambient temperature with fluid replacement. One would expect that exercise performed in the heat would exacerbate the post-exercise reductions in cardiac output due to exercise-induced decreases in central blood volume associated with a greater sweating response (loss of plasma volume) and a parallel elevated skin blood flow response (redistribution of blood to compliant cutaneous vasculature). What are the implications of a possible thermal influence on altering post-exercise haemodynamics? An earlier study by Senitko et al. (2002) compared responses between sedentary and endurance-trained individuals following exercise performed at the same relative peak oxygen consumption . A greater rate of metabolic heat production elicited by workloads based on equal percentages of a different will require substantially greater rates of sweating and skin blood flow to maintain heat balance in endurance-trained individuals. Thus, one cannot discount the possibility that the post-exercise reduction in cardiac output in trained men observed by Senitko et al. (2002) is the result of a greater sweating-related fluid loss leading to greater reductions in plasma volume and therefore central venous pressure. While Lynn et al. (2009) did not compare responses with sedentary or recreationally active individuals, their observation that exercise in the heat without fluid replacement attenuated the post-exercise reduction in cardiac output also suggests an important role for thermal factors. The notion that thermal factors might modulate the post-exercise cardiac output response is certainly an interesting one. Exercise in the heat is associated with significant cardiovascular and thermoregulatory disturbances which can persist for a prolonged period post-exercise. Thus, it is not inconceivable to suggest a possible role of thermal input in the control of cardiac output. Lynn et al. (2009) surmised that the post-exercise elevated cardiac output under warm ambient conditions may be linked to a temperature-dependent increase in myocardiac contractility (Johnson & Proppe, 1996) and/or cardiac function (Brothers et al. 2009). This was shown by the fact that the increase in cardiac output was parallelled by a concomitant increase in heart rate and occurred during a state of elevated hyperthermia (∼0.2°C above baseline resting) for the duration of recovery. In evaluating the effects of fluid replacement and heat stress on post-exercise haemodynamics, the present contribution by Lynn et al. (2009) provides a more comprehensive understanding of the mechanisms governing the post-exercise reduction in cardiac output in highly fit individuals. Further, their work establishes a strong methodological framework from which future investigations may be conducted to examine this response under conditions of increasing levels of cardiovascular (i.e. higher levels of dehydration) and thermal (i.e. elevated levels of hyperthermia) strain. While their findings show that thermal factors have an influence on post-exercise haemodynamics, the precise physiological relationship is an important area of future study.

We report the observation of permanent photoinduced birefringence in a Ge‐doped fiber exposed to cw mode locked at 532 nm. This effect is enhanced by increasing the Ge concentration in the core of the fiber, or by submitting it to a thermal hydrogen treatment. The photoinduced birefringence is however very weak, or nonexistent, with irradiation by 514 or 488 nm cw argon laser light.

A novel dual single photon emission computerized tomography (SPECT) imaging system equipped with a modular coded aperture and a conventional parallel hole collimator is introduced. An expectation maximization type blind deconvolution algorithm (EMBD) based on maximum likelihood estimation is derived for restoration of SPECT planar projections acquired by the dual imaging system. The uniformly redundant array (URA) technique is used for decoding the shadowgram acquired by the coded aperture camera head. Results of real phantom data are presented. The new configuration of the dual SPECT imaging system considerably improves the count sensitivity while still maintaining (or slightly improving) the conventional resolutions of high resolution collimation. The results also demonstrate the feasibility of the EMBD algorithm in improving image resolution and reducing background noise and non-uniformity artifacts of the decoded images. Thus, the new imaging system associated with the image restoration algorithm may be an advance of low-count nuclear imaging.

The effects of growing seedlings of red oak (Quercus rubra) and red ash (Fraxinus pennsylvanica) with Hoagland solutions containing five N-regimes, differing in the N-forms (NH4, NO3) and concentrations (High and Low), in relation to light intensity were investigated by the utilization of enzymatic markers of the N assimilation pathway, nitrate reductase (NR) and glutamine synthetase (GS). Red oak and red ash showed different patterns of N-assimilation. Red oak seedlings assimilated NO3 in low amounts in their roots and leaves, whereas red ash seedlings assimilated high amounts of NO3, mostly in the leaves. A significant amount of constitutive NR activity was found in red oak seedlings supplied with NH4 N-regime. This could be characteristic of a species adapted to soils that are poor in nitrogen. Root GS activity was lower in red oak seedlings than in red ash seedlings, indicating that the rate of NH4 assimilation differed in these two hardwood species. Low irradiance reduced growth of both hardwood species, but greatly affected the specific leaf area of red ash and reduced NO3 assimilation (when data are expressed per leaf area). Both species reacted similarly to N-regimes in terms of relative growth rate.

Light distribution in a standard scintillation camera is a complex process. The photons come across many different optical materials and many types of specular and rough optical surfaces. Complexity is further added to the model when the spatial and angular sensitivities of the detection components--the photomultipliers--are considered. To be able to correctly predict the PSF of a gamma camera, we developed a Monte-Carlo ray-tracing model which was subsequently compared to data measured on an existing gamma camera head (PRISM 3000 from Picker International Inc.). The experimental configuration was first replicated: geometry, optical properties of the crystal, light guide, photomultiplier tube window and photocathode, index matching fluid and gamma ray energy. Several other parameters, such as back mirror reflectivity and border reflectivity, were the optimized. Finally an a posteriori modelization of the scattered refracted and reflected fields at the rough interface between the crystal and the light guide was obtained by fitting simulation results to experimental data.

Gamma camera technology has evolved during the past two or three decades and is now a mature product. This paper will show that important gains can still be made at the detection level by modifying some optical components and by considering a new description of the physical phenomena. The first design modification to the detector would be to match the indices of all optical materials, from the crystal to the photomultiplier tube's window. The second and equally important point where improvement is possible is in the elimination of the spatial/spectral distortions. We will show that a complete description of the scintillation process is only possible when taking into account the depth-of-interaction (DOI) of the gamma in the crystal. Finally, the spectral contamination caused by gamma rays undergoing Compton interaction either in the object or in the detector itself is addressed by the Holospectral imaging technique. In this approach, events from the whole spectrum are accepted (as opposed to the energy windowing presently in use) and formatted into a series of energy frames. Statistical analysis is then performed on these multidimensional data to segregate object-related variance and contamination.

The different phenomena related to photoinduced self-organization in optical fiber are reviewed, from pho-toinduced absortion and refraction changes, to index grating formation and harmonic generation. Some pertinentquestions regarding the origin and the physics of these effects are exposed. 1. INTRODUCTION The optical fiber was from the beginning meant to be a transmission medium, and indeed a lot of (succesful)efforts have been made to improve its transmission properties up to the limit imposed by Rayleigh scattering. Itmay therefore appear surprising that in such a clean and transparent medium, the action of light alone can bringabout important changes in the optical properties, as have been observed in the past few years. For example,these changes make possible the formation of high reflectivity Bragg gratings [1] or second harmonic generationwith high efficiency [2]. The difficulty found in understanding these effects has prompted the organization ofthis workshop on "Photoinduced Self-organization in Optical Fiber". The aim of this introductory paper is togive a brief overview of the current questions related to photoinduced self-organization in optical fiber. As thetitle says, there are some answered questions, but also some, or even many unsanswered questions about these

Holospectral Imaging (HI), unlike the conventional technique, acquires data over a wide energy range. The new data is then used to form a series of frames corresponding to the object's spatial distribution at different energies. The multidimensional information is examined using the principal component analysis in order to characterize the different energy-dependent processes, namely: the primary photon information, the Compton scattering, the camera distorsions and the quantum noise. Each one of these factors has a typical location in the energy space RN (N is the number of energy frames). The primary photon is the main source of variance and has the most important contribution to the "principal" axis. In theory, without interference from other processes, the primaiy photon distribution defines a straight line in RN. Quantum noise will be distributed "around" this principal axis. However, scattering and camera distorsions will tend to pull the distribution toward a definite direction in the energy space. HI then finds, for each set of data, a transformation optimizing the "principal" information, the quality of this information being limited by the level of the statistical noise. Resulting images show an improvement in contrast to noise ratio and in quantitative analysis. We conclude that HI is a useful tool to describe the different contributions of scatter, camera non-uniformity and quantum noise to image variance. Therefore, energy variable should be included in the generalized transfer function of future nuclear medicine imaging systems.

We report the observation of enhanced photosensitivity in fibers exposed to a 12-atmosphere hydrogen pressure and 400C heat for 4 hours. Photosensitivity was measured with two different techniques. First, short Bragg gratings (1 cm long) were written with counterpropagating pulses from a mode- locked continuous-wave frequency-doubled Nd:YAG laser. The 80 ps pulses meet at the middle of a short strand of single-mode fiber, and the standing wave induces the formation of the grating. This portion of the fiber is maintained at a constant temperature. The grating reflectivity is measured by means of time-domain reflectometry with a fast photodiode and a sampling oscilloscope (resolution of 75 ps). Reflectivities as low as 0.1% are easily detectable. The rate of grating formation was found to be much faster in the treated fiber than in the untreated fiber. Our second technique uses the fact that the index change follows the polarization of the writing light. Thus, polarized light from the doubled Nd:YAG laser was sent through a short fiber strand, and we measured the transmission through an analyzer of a HeNe laser probe that was polarized at 45 with respect to the green beam. This technique minimizes the influence of thermal effects. Again, an increase by as much as a factor of five in the polarization rotation rate was observed in the treated fiber.

Florida scrub is a pyrogenic shrubland ecosystem occurring on well-drained sands derived from contemporary and relictual beach dunes. Despite average annual precipitation > 1300 mm, Florida scrub is dominated by xeromorphic plants. We monitored spatio-temporal variation in soil moisture to determine if the distribution of Florida scrub communities reflects patterns in soil moisture variation. Using frequency domain reflectometry, we measured soil moisture at 24 sampling stations (3 depths per station) in 3 Florida scrub communities (rosemary scrub, scrubby flatwoods, and oak–hickory scrub) at Archbold Biological Station for 3y (October 1998–September 2001). Stations were arrayed to sample 2 microhabitats (gaps, shrubs) and 2 burn histories. Soil moisture closely tracked cumulative rainfall across widely varying precipitation in the 3 y studied. Soil moisture changed through time and differed significantly among habitats; it was generally highest in scrubby flatwoods, particularly during the wette...

Fusarium solani (Mart.) Sacc., causing wilt of leaves and twigs in the crown and annual cankers on trunks and branches of red oak (Quercus rubra L.) in the field, was found for the first time in Canada. F. solani is known to occur on red or black oaks of sect. LOBATAE: nuttall oak (Q. nuttallii E. J. Palmer), red oak, willow oak (Q. phellos L.), and water oak (Q. nigra L.) throughout the eastern half of the United States (1,2). In autumn 1997 and summer 1998, the disease was observed in 10-year-old trees at an experimental plantation near Cazaville (45°03′, 74°22′) located 5 km north of New York State in the St. Lawrence Valley of Québec, where 224 of 350 (64%) of the trees were symptomatic. The fungus was isolated on 2% potato dextrose agar from the necrotic bark around the active cankers (0.5 to 32 cm long) or it was obtained as erumpent sporodochia at green bark lenticels initiated from subcortical streaks in a moist chamber (relative humidity >90%). Previously, no fungus had been isolated from brown streaks found in vascular tissues with the use of two trapping techniques, either in a moist chamber or in water. From detached dead bark, other opportunistic fungi such as an Alternaria sp., Cytospora intermedia, a Phoma sp., and a Teichospora sp. were also isolated. Koch's postulates was completed for F. solani by dipping the roots of five 2-year-old Q. rubra seedlings that had their stem collar wounded by removal of a 5 mm2 area of bark, in a conidial suspension (4 × 103 conidia per ml) for 30 min. Five control seedlings were dipped in sterile, distilled water. Plants were potted in a soil mix and incubated in a growth chamber at 22°C. Within 3 weeks, inoculated plants exhibited wilted leaves and necrotic bark symptoms similar to those originally observed. The fungus was reisolated from the leaf petioles and bark tissues of symptomatic plants, but never from the controls. After 1 month all inoculated seedlings were dead. The pathogen could have a significant impact on commercial oak production in Québec. References: (1) W. A. Sinclair et al. 1993. Diseases of Trees and Shrubs. 3th ed. Cornell University Press, Ithaca, NY. (2) E. R. Toole. Plant Dis. Rep. 50:160, 1966.

In a series of papers we have developed various mathematical models for the solid angle centered at a scintillation point and subtended by a circular photomultiplier tube (PMT) in a gamma camera. In this third paper, the scintillation crystal, where the gamma ray is converted to visible light, shows a very diffusive plane in the PMT direction. The media on each side of the boundary are homogeneous. We develop a full mathematical model for the PMT response. This model depends on several physical parameters. They can be set up according to the kind of diffusion occurring at the interface. We also show that the direct and refracted solid angles are particular cases of the diffusive model. Then, for computational purposes, we approximate the model to bring its four-level integral representation to a two-level one. Numerical results show the effectiveness of our mathematical model of the solid angle function transmitted through a diffusive plane.

Allium tricoccum is a long-lived perennial, harvested for its edible bulbs. This study provides precise information on vital rates in vulnerable populations at the northern limits of its distribution in southern Quebec. A dense population was studied for 5 years, by mapping 18 1-m × 1-m plots and measuring all ramets to estimate annual mortality, recruitment, growth, sexual and asexual reproduction rates. Ramets were classified both by their size and flowering status. A stage-classified projection matrix model was used to reveal population trends. Elasticity analyses and simulations were performed to identify the demographic variables most relevant to population growth and to estimate the effect of harvests. All vital rates estimated were closely size-dependent, and differed greatly between sterile and flowering ramets (...)

The calculation of the solid angle subtended by a given surface is required in a wide variety of applications, ranging from optics to particles transport. Integration via a Monte Carlo process is prohibitive from the computational point of view even with state-of-the-art variance reduction techniques. Exact computation of the solid angle from the distance z between the emission and the detection plane and the lateral distance ρ to the detector center requires the two-dimensional integration of a density function. We develop an approximation strategy whose form optimizes the precision requirements and the computational speed. One way to achieve this simplification is to approximate the trigonometric function in the full description of the solid angle by a series of line segments. The approximation obtained gives results that are precise to at least 1 part in 1000 and that are as fast as known algorithms.

Previously, we developed a classical solid angle function that is valid only when the light is traveling within a homogeneous medium. As soon as the light path contains a refractive interface, the direct solid angle formula is invalid. A different approach must be used if one is to include refraction effects in the solid angle formulation. The variables of integration are given more of a physical interpretation than a geometrical one: by using the emitting point instead of the detection aperture as the basis for the coordinates system, we are able to use the symmetry of the light distribution to simplify the bounds of integration. With carefully chosen coordinate changes, we are thus able to obtain an expression for the solid angle subtended by a circular aperture from a point source situated in a different optical medium. The final refracted solid angle formula also includes the expression of Fresnel's transmission coefficient.

The dynamic energy exchange between the two orthogonal modes of an elliptical-core photosensitive optical fiber was measured. We found that the polarization of the light in the fiber always tends to move toward the fast axis, which implies an asymmetry in the photosensitive properties of the fiber.

Relationships were studied between the concentrations of N, P, K, and Mg in the needles and the growth of planted white spruce (Piceaglauca (Moench) Voss) on sandy marine and associated soils at Grand'Mère, Quebec. Multiple correlation analysis indicated a positive and highly significant relationship between K concentrations and growth expressed in terms of basal area and total volume. Foliar N was positively and significantly correlated with basal area and Mg with total volume. There was a negative relationship between P concentrations and both basal area and total volume. However, the coefficients of partial correlation for N, Mg, and P were low.Significant increases in increments of basal area and total volume were obtained with 50 and 100 kg/ha K, 5 and 10 years after application. There was a moderate response in total basal area to rates of 57.5 and 115 kg/ha N in the first 5 years only. No growth response was obtained with 45 kg/ha Mg for either period of observation. K, N, and Mg were applied as K2SO4, urea, and MgSO4 respectively. No significant residual effects of N or K on foliar levels of N, K, and Mg could be established 10 years after treatment, although a marked and significant residual effect of Mg on foliar Mg concentrations could still be detected in the fertilized plots. Thus, K appeared to be the main element that limited growth of white spruce in these plantations.

The forest vegetation of the north-west section of the St. Lawrence Valley in Quebec was sampled within 68 quadrats. The location of the quadrats was selected by means of a stratified random sampling plan. Ordination (detrended correspondence analysis) and cluster analysis (TWINSPAN) allowed the identification of 11 forest community types. The ecological factors most closely associated with the distribution of these communities are soil drainage and richness. These two factors are strongly related to the types of surface deposits. Communities dominated by Acer saccharum are found on well drained and nutrient-rich moraines. On the contrary, communities dominated by Acer rubrum and the majority of coniferous forests are found on poorly drained and nutrient-poor soils. Two floristically distinct community types, the Fraxinus – Tilia americana forests and the Tsuga canadensis – Acer saccharum forests, are found on poorly drained marine deposits with edaphically identical lower horizons. However, the pH and major cation concentrations of the upper soil horizons are much lower under the cover of the hemlock forests than under the cover of the ash – basswood forests.

At the northern limit of red pine (Pinusresinosa Ait.) fire may be of critical importance in determining the persistence of red pine and its restriction to islands and shores of lakes. The objectives of the study were to document the distribution pattern of red pine populations of the Lake Duparquet area in northwestern Quebec and to analyze the age structure and fire history of the populations. The combined age structure of 22 red pine populations is balanced and uneven aged, with two periods of increased recruitment from 1805 to 1864 and from 1925 to 1974. The analysis of individual populations indicates that they can be separated into three groups associated with specific site conditions: (i) uneven-aged populations with constant recruitment occurring on xeric sites, (ii) even-aged populations without regeneration occurring on mesic sites, and (iii) uneven-aged populations, showing both a constant recruitment and peak periods of regeneration, occurring on sites with xeric and mesic portions. Although all fires registered, lethal and nonlethal, are generally asynchronous between sites, the fires of 1825 and 1944 seem to have affected large areas of the lake. Two mechanisms for the maintenance of red pine were detected: self-regeneration of populations resistant to fires on xeric sites, and the transitory colonization of mesic sites by populations susceptible to lethal fires and established by seed from distant seed sources. Red pine may be restricted to lake landscapes because of the abundance of sites protected from lethal fires.

The objective of this study is to describe the structure, composition, and ecological relationships of old-growth forests of west central Vancouver Island. Data were obtained by sampling 172 plots, at elevations up to 1000 m, located within 13 drainage areas. Relationships between vegetation and environmental variation were examined using indirect and direct gradient analysis. Successive reciprocal averaging ordinations using data from the tree, sapling, seedling, shrub, herb, and bryophyte – lichen strata led to the recognition of six vegetation groups (floodplain, subalpine, Pinus contorta, Pseudotsuga, Thuja, Abies) and 23 community types. Vegetation groups are differentiated along climatic and soil parent material gradients. The floodplain group occurs on alluvial terraces and the Pinus contorta group on rock outcrops. The vegetation of the Pseudotsuga group, dominant inland and influenced by fire disturbance, appears to respond to gradients of elevation and soil moisture. The Thuja group is found only near the coast, and its vegetation varies along gradients of soil nutrients and elevation, soil moisture having little effect. Wind is the strongest disturbance factor in this group. The vegetation patterns of the Abies group are correlated with elevation and soil moisture. Most community types of this group are associated with cool microclimates.

Data from coastal forests on west-central Vancouver Island were used to examine correlations between compositional variation in six forest strata among themselves (trees, saplings, tree seedlings, shrubs, herbs, and bryophytes) and with site environmental variables. These relationships were examined with data from three geographical areas: (i) a dry inland area dominated by Pseudotsugamenziesii, (ii) a wet coastal area dominated by Thujaplicata, and (iii) the entire study area including a few sites dominated by Abiesamabilis. Principal component analysis was used to summarize the main compositional variation within the strata of each of the three areas. Canonical correlation analysis was then used to assess the degree of correlation among strata, as well as between strata and several environmental variables. Patterns of correlation among strata differed in the three geographical areas analysed. The most strongly correlated strata were commonly associated with similar environmental factors, although the total variance in the data explained by the correlations was low (

Some aspects of the pollination ecology of a wild leek (Allium tricoccum Ait.) population were studied in Gatineau Park, Southern Quebec, Canada. Self-compatibility was determined by a pollinator exclusion experiment. Pollinator limitation of seed production was tested by comparing naturally pollinated plants with hand cross-pollinated plants. The insects observed on the umbels were collected for identification. Wild leek was found to be self-compatible. Seed production does not seem to be limited by pollinator activity. An important year to year variability of pollinator activity was observed according to the flowering intensity within the population.

The general ecology of an undescribed indigenous earthworm species in the Megascolecidae, found in the organic horizons of Podzolic soils under mixed stands of Tsugaheterophylla, Abiesamabilis, Thujaplicata, and Pseudotsugamenziesii, is described. The earthworm is a member of the genus Arctiostrotus. Over a range of sites, population numbers of earthworms were correlated to rooting concentration in and immediately below the mor humus. By micromorphological examination, earthworm casts were found to account for up to 60% by volume of the constituent solids of the organic horizons. The abundance of both fine roots and fungal hyphae in the worm casts suggested high nutrient availability. Analysis of fresh faecal material showed a marked increase in most important nutrients (N, P, K, Mg, Fe, Na) relative to levels in noningested litter. Observations indicate that this earthworm species, whose population density may reach 200 m−2, has a major role in the decomposer subsystem of these ecosystems.

Impacts of silvicultural practices on soil structure were evaluated in hardwood plantations. On two different sites, four treatments (mechanical weed control, herbicide weed control, seeding of nitrogen-fixing companion species and a control) were undertaken, with and without earthworm introduction, according to a complete randomized block design. Treatments had significant effects on the water stability of soil aggregates, macroporosity and bulk density. Earthworm introduction significantly increased macroporosity in control plots while decreasing it in the three other treatments. Key words: Soil structure, silvicultural practices, earthworm, Lumbricus terrestris

Leclair Raymond, Bourassa Jean-P., Gagnon Daniel. Exploitation de pontes d'Amphibiens par des larves de Diptères Chironomidés : étude de la coïncidence phénologique. In: Bulletin de la Société entomologique de France, volume 88 (3-4), Mars-avril 1983. Livre du Cent Cinquantenaire. Premier congrès international des entomologistes d'expression française. Paris, 6-9 juillet 1982. Comptes rendus des travaux. II. pp. 268-271.

The vegetation of the Eardley Escarpment, in Gatineau Park, was sampled in 69 stands using Whittaker's methodology. The plant communities, most of which are xeric and dominated by Quercus rubra or Pinus spp. or mesic and dominated by Acer saccharum, are analysed with indirect and direct ordinations. The analysis is based on the structure and floristic composition of the vegetation, as well as on environmental factors, disturbances, and successional status. The soils are described. The data for four meteorological stations were used to interpret microclimate. The spatial distribution of the communities seems influenced mostly by topography and fire disturbances. Two types of oak communities studied, rare or absent elsewhere in Quebec, have affinities with the Midwest.

The influence of monthly rainfall on the mean annual ring width in a 31-year-old plantation of white spruce, Picea glauca (Moench) Voss, on sandy soils near Grand'Mère, Quebec, was studied. Analysis carried out on 43 dominant trees growing without competition on a very poor dry site of coarse material indicated that current mean annual ring width is closely related to the mean monthly precipitation during June, July and August of the preceding year. Although this relationship was evident for the past 18 years, the possibility that other factors may act concurrently is recognized.

An approach to image analysis and processing, called holospectral imaging, is proposed for dealing with Compton scattering contamination in nuclear medicine imaging. The method requires that energy information be available for all detected photons. A set of frames (typically 16) representing the spatial distribution at different energies is then formed. The relationship between these energy frames is analyzed, and the original data is transformed into a series of eigenimages and eigenvalues. In this space it is possible to distinguish the specific contribution to the image of both primary and scattered photons and, in addition, noise. Under the hypothesis that the contribution of the primary photons dominates the image structure, a filtering process can be performed to reduce the scattered contamination. The proportion of scattered information removed by the filtering process is evaluated for all images and depends on the level of residual quantum noise, which is estimated from the size of the smaller eigenvalues. Results indicate a slight increase in the statistical noise but also an increase in contrast and greatly improved ability to quantitate the image. >

En fin d’année 2016, après un va-et-vient devant différentes instances judiciaires débuté en 2009, le Tribunal administratif du travail (TAT) décrétait que l’exclusion des cadres du droit d’association prévue au Code du travail ne s’appliquait pas pour les demandes déposées par les cadres de premier niveau chez Hydro-Québec ainsi qu’à la Société des casinos du Québec. Au terme de cette décision, doit-on conclure qu’à l’avenir tous les cadres de premier niveau auront droit à l’accréditation syndicale? Si tel est le cas, quelles seront les conséquences sur les unités de négociation existantes et, de façon plus générale, sur les relations de travail chez les employeurs visés par ces nouvelles demandes d’accréditation? Dans le présent exposé, nous ferons état des démarches entreprises devant les instances judiciaires pour nous pencher par la suite sur les motifs ayant justifié la décision du TAT, le tout à la lumière de l’évolution du droit d’association tel qu’établi par la Cour suprême du Canada. Au terme de cette analyse, le lecteur devrait être en mesure d’avoir sa propre opinion quant à l’issue potentielle des demandes d’accréditation déposées par des cadres de premier niveau., At the end of 2016, after a back and forth in front of different judicial bodies started in 2009, the Administrative Labor Tribunal (TAT) decreed that the exclusion of the right of association provided in the Quebec Labor Code did not apply to Hydro-Québec and the Société des casinos for their first level managers. At the end, should we conclude that in a near future all first level managers will be entitled to union accreditation? If that is the case, what will be the consequences for existing bargaining units and more generally on the labor relations of the employers targeted by this news applications for unionization? In this presentation, we will discuss the steps taken in judicial proceedings to consider later the reasons that justified the decision of the TAT, all in the light of the evolution of the right of association as established by the Supreme Court of Canada. At the end of this analysis, the reader should be able to have his or her own opinion as to the potential outcome of the requests accreditation filed by first level managers.

During a study on the litter arthropods of the natural forests of southern Quebec, Mymarommatidae specimens were found near Lachute, northwest of Montreal. Fewer than 200 specimens of Mymarommatidae have been collected throughout the world (Huber 1987); there are only nine species, all in the genus Palaeomymar Meunier (Yoshimoto 1984). Morphologically, the insects are characterized by a two-segmented abdominal petiole and atrophied posterior wings attached to the anal margin of entirely reticulated anterior wings (Huber 1987). Their biology is still unknown (J.T. Huber, pers. comm.), although it is thought that they may be insect egg parasites (Yoshimoto 1984). Yoshimoto (1984) included the Mymarommatidae in the Chalcidoidea. However, Gibson (1986) proposed not to include them in a superfamily until the phyletic relationships of the Terebrantes are better defined.

In a 1984 study on the ecological factors influencing the forest vegetation in the southern region of the province of Quebec (Gauthier 1985; St-Jacques 1986), an adult specimen of Cleruchus biciliatus (Ferrière) was found. This is the first record of the occurrence of the species in North America.Sampling was done in 120 sites selected in a stratified random design in natural forests of the Mirabel area, northwest of Montreal (from 45°33' to 45°45'N and from 74°3' to 74°44'W). At each site, vegetation was sampled from an area 20 by 50 m. A 400-cm2 sample of litter was taken from each of these areas. In the laboratory, the litter samples were put into modified Berless funnels (Phillipson 1971). Following a 48-h extraction process, the organisms, collected in 70% ethyl alcohol, were identified and counted.

NAULT, A. AND D. GAGNON (Dept. Sci. biol., Univ. du Quebec a Montreal, Groupe Rech. Ecol. Forest., Montreal, Quebec H3C 3P8, Canada). Seasonal biomass and nutrient allocation patterns in wild leek (Allium tricoccum Ait.), a spring geophyte. Bull. Torrey Bot. Club 115: 45-54. 1988.-Biomass and nutrient allocation patterns were studied during the growing season in a wild leek (Allium tricoccum Ait.) population in southern Quebec, Canada. Wild leek is a spring geophyte in which the photosynthetic phase precedes and does not overlap the reproductive phase. N, P, K, Mg and Ca allocation to plant structures was studied concurrently with biomass allocation in reproductive plants during the 1983 growing season. Biomass allocation to individuals of all size-classes (divided into two size-classes) of the population was studied in 1984 and 1985. Patterns observed are typical of plants with a spring ephemeral phenology, such as a high investment to leaves during the short photosynthetic period. The large allocation to the bulb suggests a conservative survival strategy, based primarily on vegetative propagation. Nutrient and biomass allocation patterns were largely similar, except for mobile nutrients (N and P) in the scape. Little variation in biomass allocation was seen in large reproductive wild leek plants from year to year; smaller, non-reproductive plants showed higher variability, probably because of higher phenological response to climate.

The objectives of this study were to compare coarse root (diameter > 2 mm) and fine root (diameter