Net Increment Research Articles

PERIODATE-CATALYZED OXIDATIVE COUPLING OF ANILINE-DERIVED P-AMINOPHENOL WITH P-XYLENOL AS A DETECTION METHOD FOR HYDROXYL RADICALS

A simple spectrophotometric method for rapid detection of hydroxyl radical (•OH) has been developed. The principle of the method depends upon the hydroxylation of a trapping agent, aniline, by •OH leading to the formation of various hydroxylated products. One of these hydroxylated products, p-aminophenol (PAP), is capable of undergoing an oxidative coupling reaction with p-xylenol (2,5-dimethylphenol) catalyzed by sodium periodate. The resultant indophenol-derivative formed can be measured spectrophotometrically at 635 nm. The net increment of absorbance at 635 nm can then be used to estimate the degree of hydroxylation of aniline, which is dependent upon the amount of •OH present in the assay system. A specific example for estimating the •OH-scavenging abilities of food products is also given.

Sustainable management regimes for Europe's forests — a projection with EFISCEN until 2050

In Europe, forest policy discussions are moving towards a European Union-wide strategy. This will further intensify the relations between European countries in the field of forests and forest management. European-wide forest planning and decision-making require that policy makers have insight into the long-term development of European forests under alternative regimes. The European Forest Information Scenario Model (EFISCEN) was used to make projections of the development of the European forests under four scenarios: (1) business as usual; (2) EFISCEN European timber trend studies (ETTS); (3) maximum sustainable production; and (4) multifunctional management. The simulations were carried out for 30 countries individually, i.e. harmonized scenarios were run, but the special circumstances and demands that play a role in each country were taken into account. The simulations covered 139.2 million ha increasing to 143 million ha in 2050. The initial year varied per country, but was mostly in the region of 1990. The average age of European forests was 57 years in 1990 with a mean growing stock of 142 m 3 ha −1. The results showed that the future European total fellings may vary between a stable amount of 400 million m 3 year −1 in the ‘business as usual’ scenario to 647 million m 3 year −1 in the ‘maximum sustainable production’ scenario. The other two scenarios incorporated a 9% gradual increase in fellings over the first 30 years of the simulation period (i.e. 0.3% year −1). The average growing stock will rise to approximately 250 m 3 ha −1 in 2050, with the exception being the ‘maximum sustainable production’ scenario, in which the growing remains at approximately 137 m 3 ha −1. The average net annual increment remains at approximately 5 m 3 ha −1 year −1 throughout the simulation period, almost irrespective of the scenario. In the multifunctional scenario, special attention was paid to nature values by increasing the area of strict reserves from 4 million ha in 1990 to 12.3 million ha in 2050 (8.6% of the total forest area). The assumed increase in fellings of 0.3% year −1 appeared possible in combination with this area of reserves. The simulations showed that growing stock development and increment development differed very much for each country separately per scenario. Therefore, the results show a strong need for maintaining the national diversity that constitutes European forestry within harmonized European-wide forest management strategies. In this article, we address what the consequences of each scenario are for wood production, biodiversity, and environmental functions of the forest. The results provide policy makers with a challenge on whether to intervene in the ongoing trend of build-up of growing stock and whether to choose for biodiversity, for increased use of domestically produced wood products, or a combination of these, but spatially separated.

Is Asthma a Risk Factor for Dental Caries? Findings from a Cohort Study

It has been suggested that asthmatic children may have a higher caries risk, both as a result of their medical condition and the physical and physiological effects of their pharmacotherapy. By examining the association over time between asthma and caries increment, this study tested the hypothesis that childhood asthma is associated with an increased caries increment. In a long–standing New Zealand cohort study, participants’ long–term asthma histories and the 3–year net caries increment between the ages of 15 and 18 years were examined. Of the 781 who were examined at 15 and 18 years, 39 participants were consistently taking anti–asthma medication at the ages of 9, 11, 13 and 15 years (and were labelled in this study as ‘medication–determined asthmatics’), 56 were identified as consistent wheezers at the ages of 9, 11, 13 and 15 years (‘wheeze–determined asthmatics’) and 36 were members of both groups. A smaller group (n = 9) was identified as being very–long–term asthmatics (asthma at 5 years of age and at the ages of 9, 11, 13 and 15 years). Some 206 study members were identified as having no history of asthma, asthma medication or significant wheeze at any time up to and including 18 years. The overall mean net caries increment between the ages of 15 and 18 years was 2.06 surfaces (SD, 3.76). There were no significant differences in caries increment between the 206 asthma–free participants and any of the asthma groups. This study provides little evidence for an asthma–caries causative relationship.

Adrenocortical Secretion of Dehydroepiandrosterone in Healthy Women: Highly Variable Response to Adrenocorticotropin

Excess adrenal androgen (AA) levels are observed in 25--50% of women with the polycystic ovary syndrome (PCOS), and AA excess in PCOS may represent selection bias. Thus, it is possible that AA secretion among the general population is highly variable, and that those women who are predisposed to secreting greater amounts of AA have a greater probability of having PCOS. We now hypothesize that the levels of AAs are highly variable among normal nonhyperandrogenic women, and that this heterogeneity is the result of a variable response of AAs to ACTH stimulation. To test this hypothesis we prospectively studied the response of dehydroepiandrosterone (DHA) and cortisol (F) to a 60-min acute stimulation with ACTH-(1--24) in 56 healthy eumenorrheic nonhirsute healthy women with a mean age of 28.9 yr (range, 20--37 yr.) and a mean body mass index (BMI) of 29.2 kg/m(2) (18.2--46.2 kg/m(2)). Baseline samples and poststimulation samples were assayed for DHA and F. The basal and ACTH-stimulated levels of DHA, but not those of F, were negatively correlated with age, although neither the basal nor ACTH-stimulated responses of DHA and F varied with BMI. After controlling for age, the basal F level was negatively correlated to its net increment (i.e. Delta F; r = -0.54; P < 0.001), whereas there was no significant relationship between basal DHA and Delta DHA. We also compared the intersubject variability (coefficient of variation) for basal and stimulated levels of DHA and F. For basal (DHA(0)), 60 min (DHA(60)), and net increment in (Delta DHA) DHA levels, the coefficients of variation were 67.9%, 61.4%, and 76.0%, respectively; for F(0), F(60), and Delta F, they were 40.4%, 16.9%, and 31.3%, respectively. The variance in Delta DHA was significantly higher, and the variance in F(60) was significantly lower than that in all other variables; DHA(0), DHA(60), F(0), and Delta F had similar variances. In conclusion, in our population of healthy reproductive-aged women we observed that both basal and ACTH-stimulated levels of DHA after ACTH-(1--24) stimulation had significantly greater intersubject variance (approximately 60--70%) compared with the basal and poststimulation levels of F (approximately 15--40%). These data support the hypothesis that among normal women, AA (i.e. DHA) levels are highly variable compared to those of F. In addition, the intersubject variability in DHA levels is at least in part due to a variable response of AAs to ACTH stimulation. Whether the AA excess frequently observed in PCOS is due to the greater risk of those women with higher AA levels, basally and after ACTH stimulation, remains to be confirmed.

Adrenocortical secretion of dehydroepiandrosterone in healthy women: highly variable response to adrenocorticotropin.

Excess adrenal androgen (AA) levels are observed in 25--50% of women with the polycystic ovary syndrome (PCOS), and AA excess in PCOS may represent selection bias. Thus, it is possible that AA secretion among the general population is highly variable, and that those women who are predisposed to secreting greater amounts of AA have a greater probability of having PCOS. We now hypothesize that the levels of AAs are highly variable among normal nonhyperandrogenic women, and that this heterogeneity is the result of a variable response of AAs to ACTH stimulation. To test this hypothesis we prospectively studied the response of dehydroepiandrosterone (DHA) and cortisol (F) to a 60-min acute stimulation with ACTH-(1--24) in 56 healthy eumenorrheic nonhirsute healthy women with a mean age of 28.9 yr (range, 20--37 yr.) and a mean body mass index (BMI) of 29.2 kg/m(2) (18.2--46.2 kg/m(2)). Baseline samples and poststimulation samples were assayed for DHA and F. The basal and ACTH-stimulated levels of DHA, but not those of F, were negatively correlated with age, although neither the basal nor ACTH-stimulated responses of DHA and F varied with BMI. After controlling for age, the basal F level was negatively correlated to its net increment (i.e. Delta F; r = -0.54; P < 0.001), whereas there was no significant relationship between basal DHA and Delta DHA. We also compared the intersubject variability (coefficient of variation) for basal and stimulated levels of DHA and F. For basal (DHA(0)), 60 min (DHA(60)), and net increment in (Delta DHA) DHA levels, the coefficients of variation were 67.9%, 61.4%, and 76.0%, respectively; for F(0), F(60), and Delta F, they were 40.4%, 16.9%, and 31.3%, respectively. The variance in Delta DHA was significantly higher, and the variance in F(60) was significantly lower than that in all other variables; DHA(0), DHA(60), F(0), and Delta F had similar variances. In conclusion, in our population of healthy reproductive-aged women we observed that both basal and ACTH-stimulated levels of DHA after ACTH-(1--24) stimulation had significantly greater intersubject variance (approximately 60--70%) compared with the basal and poststimulation levels of F (approximately 15--40%). These data support the hypothesis that among normal women, AA (i.e. DHA) levels are highly variable compared to those of F. In addition, the intersubject variability in DHA levels is at least in part due to a variable response of AAs to ACTH stimulation. Whether the AA excess frequently observed in PCOS is due to the greater risk of those women with higher AA levels, basally and after ACTH stimulation, remains to be confirmed.

Circulating thyrotropin bioactivity in sporadic central hypothyroidism.

The etiopathogenesis of sporadic central hypothyroidism (CH) involves pituitary and hypothalamic lesions. Pituitary CH (pCH) implies a diminished number of functioning thyrotropes, accounting for the quantitative impairment of TSH secretion. Hypothalamic CH (hCH) is characterized by normal or even increased TSH concentrations and qualitative abnormalities of TSH secretion, including a decreased bioactivity of circulating TSH. However, controversy still exists about the actual occurrence of bioinactive TSH among CH patients, and no data are available in pCH. Therefore, we studied 41 CH patients with different hypothalamic-pituitary disorders. Immunoreactive TSH (TSH-I) ranged from 0.08-11.1 mU/L (normal, 0.24-4.0), free T4 (FT4) ranged from 0.6-8.8 pmol/L (normal, 9-18), and FT3 ranged from 1.2-5.4 pmol/L (normal, 4-8). A blunted TSH response to TRH (<4 mU/L), indicating prevalent pCH, was found in 56% of the patients, and a net TSH-I increment > or =4 mU/L, indicating prevalent hCH, was found in the remaining 44%. Net TSH-I increments showed significant correlation with basal FT4 (P < 0.02), indicating the relevance of pituitary TSH reserve in the pathogenesis of CH. Circulating TSH was immunoconcentrated and tested in bioassay and in ricin affinity chromatography. The ratio between biological (B) and immunological (I) activities of circulating TSH was reduced (n = 25; TSH B/I, 0.38+/-0.19) compared to the values recorded in normal subjects (n = 26; TSH B/I, 1.53+/-0.54; P < 0.001) and primary hypothyroid patients (n = 24; TSH B/I, 0.74+/-0.31; P < 0.001), but no difference between pCH (n = 9; 0.36+/-0.16) and hCH (n = 16; 0.39+/-0.20) was seen. TSH B/I values in CH patients showed a limited overlap with normal values (20%) and a highly significant correlation with the FT3 response to endogenous TRH-stimulated TSH (P < 0.005). The elevated sialylation degree of TSH molecules may explain part of these findings. In conclusion, the secretion of TSH molecules with reduced bioactivity is a common alteration in the patients with hypothalamic-pituitary lesions, contributing along with the impairment of pituitary TSH reserve to the pathogenesis of CH.

Low glycaemic-index foods.

Accumulating data indicate that a diet characterized by low glycaemic-index (GI) foods not only improves certain metabolic ramifications of insulin resistance, but also reduces insulin resistance per se. Epidemiological data also suggest a protective role against development of non-insulin-dependent diabetes mellitus and cardiovascular disease. A major disadvantage in this connection is the shortage of low-GI foods, and many common starchy staple foods, such as bread products, breakfast cereals and potato products, have a high GI. Studies in our laboratory show that it is possible to significantly lower the GI of starchy foods, for example by choice of raw material and/or by optimizing the processing conditions. Such low-GI foods may or may not influence glucose tolerance at a subsequent meal. Consequently, certain low-GI breakfasts capable of maintaining a net increment in blood glucose and insulin at the time of the next meal significantly reduced post-prandial glycaemia and insulinaemia following a standardized lunch meal, whereas others had no 'second-meal' impact. These results imply that certain low-GI foods may be more efficient in modulating metabolism in the long term. Although the literature supports a linear correlation between the GI and insulinaemic index (II) of foods, this is not always the case. Consequently, milk products elicited elevated IIs, indistinguishable from a white bread reference meal, despite GIs in the lower range. This inconsistent behaviour of milk products has not been acknowledged, and potential metabolic consequences remain to be elucidated.

Validation of the European Forest Information Scenario Model (EFISCEN) and a projection of Finnish forests

Large-scale forest scenario models are intensively used to make projections of forest areas of up to hundreds of millions of hectares. Within Europe, such projections have been done for 11 countries at the individual national scale, most often to foresee the long-term implications of the ongoing forest management. However, the validity of the models has rarely been tested. The aim of this study was 1. to validate the European Forest Information SCENario model (EFISCEN) by running it on historic Finnish forest inventory data, 2. to improve the model based on the validation, and 3. to project the Finnish forest development till 2050 with the improved model under alternative scenarios. The results of the validation showed that EFISCEN is capable of making reliable large-scale projections of forest resources for periods up to 50–60 years. Based on the validation, the model was improved concerning simulation of age development, thinning regimes and regrowth after thinning. The projection of the Finnish forests till 2050 with the improved model presented a maximum sustainable felling level of around 70 million m3 per year. That provides an average growing stock of 106 m3 ha–1 in 2050 and a net annual increment of 3.6 m3 ha–1 y–1. If the current trend towards more nature oriented forest management continues and 1.39 million ha of forests have been set aside additionally for nature reserves by 2050, the felling level could meet a realistic demand of 57 million m3 per year in 2050. Under the latter regime the average growing stock will have grown to 160 m3 ha–1 in 2050.

Daily stem growth patterns in irrigated Eucalyptus globulus and E. nitens in relation to climate

Daily increments in stem radius were determined from hourly dendrometer measurements in each of three irrigated Eucalyptus nitens and E. globulus trees. Multiple regressions determined from daily weather variables accounted for 40–50% of the variance in increment. The use of weather variables lagged by 1–2 days increased the variance explained. The diurnal variation in stem radius was resolved into three mathematically defined phases: shrinkage, recovery and increment. The positive daily net increment in stem radius, by definition, occurred in the increment phase. Average weather conditions during this phase (predominantly night-time) did not explain any more variance in increment than the average daily conditions, determined over a 24 h period. Daily increment was resolved into a rate of stem radius increase during the increment phase and the duration (hours) of that phase. Significant species by month interactions were evident with growth in summer characterised by faster rates of stem expansion over shorter time periods within each diurnal cycle. E. nitens tended to have longer increment phases in spring and autumn, and faster phase rates in autumn than E. globulus. Interactions between weather variables and cambial growth were complicated and varied over the year. The correlation between temperature and stem growth varied from positive in spring to zero or negative during summer. The data indicate a need to understand weather-by- climate interactions at the level of whole tree physiology in order to fully understand the effect of weather on cambial activity and therefore stem increment and wood properties.

Effect on the Biosphere of Elevated Atmospheric CO 2

The report “Net primary production of a forest ecosystem with experimental CO2 by enrichment” by E.H. DeLucia et al. (14 May, p. [1177][1]) provides excellent and much-needed experimental work on the responses of the terrestrial biosphere to elevated atmospheric carbon dioxide (CO2). However, we are concerned about the report's last statement (also appearing in the abstract), which extrapolates measurements of net primary production (NPP) from this one experiment to the world's forests as a whole, suggesting that they could absorb as much as 50% of the projected fossil fuel emissions of CO2 in 2050. This projection gives a misleading, perhaps erroneous, picture of the role of the terrestrial biosphere in the global carbon cycle. First, NPP is not the appropriate measurement to apply when considering the net uptake (or release) of CO2 by the terrestrial biosphere on a biome or larger spatial scale and over several decades. The most appropriate concept is net biome production (NBP) ([1][2]), which includes not only NPP, but also losses of carbon resulting from heterotrophic respiration, fires, insect-induced mortality, logging, and other natural and human-induced disturbances ([2][3]). In contrast to global terrestrial NPP, which is about 60 picograms of carbon per year, global terrestrial NBP is about ± 1 or 2 picograms per year. Second, there is considerable difficulty in extrapolating up in time and space from a single experiment based on a step-change in CO2 concentration over a young, rapidly growing stand of trees, as noted by the authors of the report immediately before the final statement. Third, applying the same methodology for extrapolation as used in this report, we conclude that the world's forests should now be taking up at least 3 picograms of carbon per year of fossil-fuel emissions. This is significantly higher than current estimates of terrestrial carbon sequestration [for example, ([3][4])] and is inconsistent with atmospheric inverse calculations, as well as with estimates of oceanic carbon uptake. In the current, post-Kyoto international political climate, scientific statements about the behavior of the terrestrial carbon cycle must be made with care, especially extrapolations from stand-level experiments or observations. 1. [↵][5]1. J.N. Galloway, 2. J.M. Melillo 1. E.D. Schulze, 2. M. Heimann , in Asian Change in the Context of Global Change, J.N. Galloway, J.M. Melillo, Eds. (Cambridge Univ. Press, Cambridge, 1998), pp. 145-161 (No. 3, IGBP Book Series,. 2. [↵][6]1. IGBP Terrestrial Carbon Working Group , Science 280, 1393 (1998). [OpenUrl][7][Abstract/FREE Full Text][8] 3. [↵][9]1. D.S. Schimel , Global Change Biol. 1, 77 (1995). [OpenUrl][10] # Effect on the Biosphere of Elevated Atmospheric CO2 {#article-title-2} NPP is the difference between total, annually integrated photosynthesis (gross primary production) and plant respiration and therefore represents the rate of carbon uptake from the atmosphere by ecosystems ([1][2]). By assuming that all forests of the world are similar to our young, fast-growing stand of loblolly pine, we attempted to constrain an estimate of the maximum net increment of NPP when the atmosphere contains 560 parts per million of CO2. Our value for forest uptake, 50% of the anticipated CO2 emissions from fossil fuels in the year 2050, indicates that forests will not solve the global warming problem for us. And, as Bolin et al. indicate, actual long-term carbon storage will be much less than NPP, owing to the activity of soil microbes, fires, human land-use changes, and so forth, which act to return CO2 to the atmosphere. 1. 1. W.H. Schlesinger , Biogeochemistry (Academic Press, San Diego, CA, 1997). [1]: /lookup/doi/10.1126/science.284.5417.1177 [2]: #ref-1 [3]: #ref-2 [4]: #ref-3 [5]: #xref-ref-1-1 View reference 1 in text [6]: #xref-ref-2-1 View reference 2 in text [7]: {openurl}?query=rft.jtitle%253DScience%26rft.stitle%253DScience%26rft.issn%253D0036-8075%26rft.aulast%253DIGBP%2BTerrestrial%2BCarbon%2BWorking%2BGroup%26rft.auinit1%253D%2B%26rft.volume%253D280%26rft.issue%253D5368%26rft.spage%253D1393%26rft.epage%253D1394%26rft.atitle%253DCLIMATE%253A%2B%2BThe%2BTerrestrial%2BCarbon%2BCycle%253A%2BImplications%2Bfor%2Bthe%2BKyoto%2BProtocol%26rft_id%253Dinfo%253Adoi%252F10.1126%252Fscience.280.5368.1393%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx [8]: /lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6Mzoic2NpIjtzOjU6InJlc2lkIjtzOjEzOiIyODAvNTM2OC8xMzkzIjtzOjQ6ImF0b20iO3M6MjU6Ii9zY2kvMjg1LzU0MzUvMTg0OS45LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ== [9]: #xref-ref-3-1 View reference 3 in text [10]: {openurl}?query=rft.jtitle%253DGlobal%2BChange%2BBiol.%26rft.volume%253D1%26rft.spage%253D77%26rft.atitle%253DGLOBAL%2BCHANGE%2BBIOL%26rft.genre%253Darticle%26rft_val_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Ajournal%26ctx_ver%253DZ39.88-2004%26url_ver%253DZ39.88-2004%26url_ctx_fmt%253Dinfo%253Aofi%252Ffmt%253Akev%253Amtx%253Actx

Asymptotics of palm-stationary buffer content distributions in fluid flow queues

We study a fluid flow queueing system with m independent sources alternating between periods of silence and activity; m ≥ 2. The distribution function of the activity periods of one source, is supposed to be intermediate regular varying. We show that the distribution of the net increment of the buffer during an aggregate activity period (i.e. when at least one source is active) is asymptotically tail-equivalent to the distribution of the net input during a single activity period with intermediate regular varying distribution function. In this way, we arrive at an asymptotic representation of the Palm-stationary tail-function of the buffer content at the beginning of aggregate activity periods. Our approach is probabilistic and extends recent results of Boxma (1996; 1997) who considered the special case of regular variation.

Asymptotics of palm-stationary buffer content distributions in fluid flow queues

We study a fluid flow queueing system with m independent sources alternating between periods of silence and activity; m ≥ 2. The distribution function of the activity periods of one source, is supposed to be intermediate regular varying. We show that the distribution of the net increment of the buffer during an aggregate activity period (i.e. when at least one source is active) is asymptotically tail-equivalent to the distribution of the net input during a single activity period with intermediate regular varying distribution function. In this way, we arrive at an asymptotic representation of the Palm-stationary tail-function of the buffer content at the beginning of aggregate activity periods. Our approach is probabilistic and extends recent results of Boxma (1996; 1997) who considered the special case of regular variation.

Long‐term growth dynamics of natural forests in Hokkaido, northern Japan

Abstract. The long‐term growth dynamics of natural forest stands on the island of Hokkaido were described on the basis of an analysis of data from 38 permanent plots spanning 15–22 yr. Stand structure was characterized by basal area, stem density and tree size variability. To detect trends in stand structure, regression models for recruitment rate (per ha per yr), mortality rate and the rate of change in stem density and tree size variability were developed by a stepwise method using initial basal area, stem density, tree size variability, species composition summarized by LNMDS ordination, altitude, annual mean temperature, annual precipitation, type of understorey vegetation, topography and slope aspect as candidates for predictor variables. The same analyses were conducted for basal area increment (net growth) and its components: survivor growth = basal area gain by growth of surviving individuals and mortality = basal area loss by death of individuals.Stem density remained generally unchanged; recruitment was relatively low even in very sparse stands. Stand basal area generally increased as survivor growth was approximately double the mortality.Recruitment rate was strongly affected by the presence of dwarf bamboo (Sasa spp.) vegetation on the forest floor which inhibited tree regeneration. Mortality rate was density‐dependent; dense stands had higher mortality than sparse stands. Density change rate (recruitment rate ‐ mortality rate) was, therefore, determined by both the type of understorey vegetation and stem density. Survivor growth was high in stands with high stem density and basal area. Mortality was dependent on basal area and altitude. Net basal area increment (net growth) was dependent only on stem density with other factors that influenced survivor growth and mortality omitted. Tree size variability decreased in stands with high tree size variability whereas it increased in stands with low size variability. Based on the obtained models for density change rate and net basal area increment, trajectories of stands were illustrated on a log‐log diagram of stem density and basal area. The predicted differences in trajectories as affected by the understorey vegetation type indicated the importance of dwarf bamboo vegetation for forest dynamics on Hokkaido.

A Comparison of Increment and Incidence Density Analyses in Evaluating the Anticaries Effects of Two Dentifrices

This study aimed to determine whether incidence density (ID) calculations of caries incidence rates would provide a more sensitive means of detecting caries–preventive effects than would traditional techniques. A secondary analysis was conducted using data from a 1981 study in which three dentifrices were compared in a double–blind randomized clinical trial. Subjects were examined at baseline and 1, 2 and 3 years after baseline. Three–year DMFS increments were calculated for 1,754 subjects attending the baseline and 3–year examinations. Caries ID rates then were calculated for 2,661 subjects who had at least two examinations, using each surface's net increment (–1, 0 or +1) as the numerator and the surface's time at risk as the denominator. Despite theoretical advantages, the ID method did not alter the conclusions drawn using DMFS increments, apparently because (a) subjects lost to follow–up were similar to those completing the study, and (b) loss to follow–up was similar among treatment groups.

Androgen response to hypothalamic-pituitary-adrenal stimulation with naloxone in women with myotonic muscular dystrophy.

Myotonic muscular dystrophy (MMD) is a disease of autosomal dominant inheritance characterized by multisystem disease, including myotonia, muscle-wasting and weakness of all muscular tissues, and endocrine abnormalities attributed to a genetic abnormality causing a defective cAMP-dependent kinase. We have previously reported that MMD patients demonstrate ACTH hypersecretion after endogenous CRH release stimulated by naloxone administration while manifesting a normal cortisol (F) response. Additionally, others have reported a reduced adrenal androgen (AA) response to exogenous ACTH administration in MMD patients. As ACTH stimulates the secretion of both AAs and F, it is possible that the discordant relationship of these hormones in MMD patients results from a defect of adrenocortical ACTH receptor function or postreceptor signaling or subsequent biochemical events. Furthermore, the molecular abnormality seen in MMD patients may suggest that the mechanism underlying the frequently observed discordances in the secretion of glucocorticoids and AAs (e.g. adrenarche, surgical trauma, severe burns, or intermittent glucocorticoid administration) are explainable solely via an alteration in the function of the ACTH receptor or postreceptor signaling. To ascertain whether the responses of F and AAs to endogenous ACTH diverged in this disorder, we prospectively studied the responses of these hormones to naloxone-stimulated CRH release in nine premenopausal women with MMD and seven healthy age and weight-matched control women. After naloxone infusion (125 micrograms/kg, i.v.), blood sampling was performed at baseline (i.e. -5 min) and at 30 and 60 min. In addition to the absolute hormone level at each time, we calculated the net increment (i.e. change) at 30 and 60 min and the area under the curve (AUC) for F, ACTH, dehydroepiandrosterone (DHA), and androstenedione (A4). Consistent with our previous study, MMD patients demonstrated higher ACTH levels at all sampling times except [minud]5 min. AUC analysis revealed the ACTHAUC values were significantly higher in MMD than in control women (457 +/- 346 vs. 157 +/- 123 pmol/min.L; P < 0.03), whereas the FAUC response did not differ between MMD and controls (13860 +/- 3473 vs. 13375 +/- 3465 nmol/min.L; P > 0.5). Despite the greater ACTH secretion, the baseline circulating dehydroepiandrosterone sulfate levels were significantly lower in MMD compared with control women (18 +/- 23 vs. 61 +/- 23 mumol/L; P < 0.002). The serum concentrations of A4 at baseline, 30 min, and 60 min and DHA levels at 30 and 60 min were also significantly lower in MMD vs. control women. Additionally, the A4AUC and DHAAUC values were significantly lower in MMD patients than in controls. Furthermore, the net response of DHA at 60 min to the endogenous ACTH increase was also reduced in MMD patients compared with that in control subjects (2.3 +/- 2.1 vs. 5.6 +/- 2.6 nmol/L; P < 0.02). In conclusion, in addition to ACTH hypersecretion to CRH-mediated stimuli, these data suggest that MMD patients have a defect in the adrenocortical response to ACTH, reflected in normal F and reduced DHA and A4 secretion. Whether this defect is inherent to the disease or simply reflects adaptive changes to chronic disease remains to be demonstrated. However, it is possible that further studies of the response of MMD patients to ACTH may reveal a mechanism that explains the frequently observed dichotomy in the secretion of glucocorticoids and AAs.

The Rapid Inhibitory Effect of Glucocorticoid on Cytosolic Free Ca2+Increment Induced by High Extracellular K+and Its Underlying Mechanism in PC12 Cells

The effect of glucocorticoid(GC) on peak cytosolic free calcium net increment (Δ [Ca2+]i) induced by high-K+was deteced with MiraCal Image System. The main results were as follows: (1) Corticosterone(B) could inhibit Δ[ Ca2+]iin a time-dependent and concentration-dependent manner. (2) The inhibitory effect of B could be mimicked by bovine-serum albumin conjugated corticosterone (B-BSA) also in a dose-dependent manner. (3) G-protein inhibitor, either PTX or GDPβS significantly reduced the inhibitory effect of B and B-BSA on Δ[ Ca2+]i(4) PMA, a stimulator for protein kinase C(PKC), could inhibit Δ[Ca2+]i. (5) Although the inhibitors of PKC,chelerythrine chloride and bisindolylamide Iper sehad no influence on Δ[ Ca2+]i, but they significantly antagonized the inhibitory effect of B and B-BSA on Δ[ Ca2+]i. It is postulated that GC inhibit Δ[Ca2+]iinduced by high-K+through a membrane mechanism and by a pathway involving G-protein and PKC.

Développement de sapinières éclaircies exposées à une épidémie de tordeuse des bourgeons de l'épinette

In 1968, three intensities of low thinning were applied in 33-year-old balsam fir (Abies balsamea [L.] Mill.) stands of eastern Québec in order to remove 0, 20 and 30% of the total basal area. Sample plots were located in two distinct areas, one of which was annually sprayed with insecticides between 1978 and 1982 while the other was never protected against a spruce budworm (Choristoneura fumiferana [Clem.]) outbreak that occurred between 1976 and 1983. A total of 32 0.04-ha sample plots were periodically measured between 1968 and 1994. Low thinnings mostly removed non merchantable trees (DBH &lt; 9.1 cm) and left 5 000 to 7 000 trees/ha while stand density of control plots reached 10 000 stems/ha. From 1968 to 1976, net annual increment in merchantable volume was around 8 m3/ha but no differences were detected between thinning levels. During the period of severe defoliation caused by spruce budworm (1976-1985), net annual increment in merchantable volume of sample plots sprayed with insecticides decreased by 50% but get back to its initial level after 1985. Net annual increment of sample plots that were never protected against spruce budworm was strongly negative during the outbreak period until the extinction of all trees was completed. While thinning level only slightly affected merchantable yield of sample plots during the 26-year period, mean annual increment in DBH was inversely proportional to stand density. This advantage of thinned plots could have been greater if stand density had been reduced further at the beginning of the study. Indeed, the analysis of the evolution of stand density as a function of mean volume of trees shows that mortality rate of all sample plots was similar to that given by the self-thinning rule. This suggests that even trees of most heavily thinned plots suffered from strong intra-specific competition. Key words: balsam fir, low thinning, spruce budworm, growth and yield, diameter increment, self-thinning rule

Accurate path integral representations of the Fokker-Planck equation with a linear reference system: Comparative study of current theories

This paper presents an application of new discrete path integral solutions recently introduced for Fokker-Planck dynamics with the aim to compare their relative efficacy in giving precise numerical results. The basic idea used in the derivation of these solutions is to model a complex Fokker-Planck equation with a general drift coefficient by a linear (Ornstein-Uhlenbeck) process, which is solved exactly, and to then employ an iterative technique to quantify what is missing from the reference description. We reexamine and analyze two different approaches to realize the above strategy. These are an operator decoupling technique and a power series expansion method. Both approaches allow one to construct higher-order propagators valid to any desired precision in a time increment $\ensuremath{\tau}$. Their use in a path integral means that many fewer time steps $N$ are required to achieve a given accuracy for a given net increment $t=N\ensuremath{\tau}$. Our comparison also includes results from standard path integral representations. The relative efficacy of the various different methods is illustrated by means of two problems, namely, the dynamics of an overdamped Brownian particle in a potential field and the Kramers model of chemical reaction. The former process can be modeled by a one-dimensional Fokker-Planck equation for the position coordinate only, while the latter is governed by a two-dimensional Fokker-Planck equation where the relaxation over velocity is taken into account. The numerical applications clearly demonstrate that the new representations are superior in the sense that they yield much more accurate results with less computational effort than the best alternative path integral method now in use.

The analysis of return and its components of non-industrial private forest ownership by forestry board districts in Finland

Non-industrial private forest ownership returns and risks in Finland are both estimated and disaggregated to local Forestry Board Districts (FBD) level. Additionally, the FBD level return is divided into price change, felling and change in the growing stock components, which are compared with the inflation rate. The results are based on a complete count of the stumpage prices, silvicultural costs and state subsidies as well as the National Forest Inventory (NFI) data. The influence of taxation is discussed as well. Although this database is excellent for economic studies as well, the estimation methodology is vitiated by a host of problems, the resolution of which is the major contribution of this study. The study period is 1972–1996. The results show that there have been fairly large differences in forest ownership returns and prices depending on the Forestry Board District. Results show that the price change component has been larger in Northern Forestry Board Districts, as much as 0.9% above the inflation rate in Lapland FBD, than in Southern Forestry Board Districts, 1.5% less than the inflation rate in southern Helsinki FBD. The net increase, however, has been larger in Southern Forestry Board Districts than in Northern Forestry Board Districts. Using the average net increment in Finland as a comparison base, the net increment in South Karelia exceeded it by 0.6%, but fell below it by 1.8% in Northeastern Finland. Finally, the return over the whole period is compared to the return on private housing and inflation in the case of North Savo. In all, the estimation methodology developed also serves as spin-off product development for the Forest Statistics Information Service (FSIS).

High-accuracy discrete path integral solutions for stochastic processes with noninvertible diffusion matrices. II. Numerical evaluation

We present a fast, high precision and easily implementable path integral method for numerically solving Fokker–Planck equations. It is based on a generalized Trotter formula, which permits one to attain an adequate description of dynamical and equilibrium properties even though the time increment τ=t/N is rather large. A remarkable property of the symmetric Trotter splitting is used to systematically eliminate the lower-order errors resulting from time discretization. This means a significant reduction of the number of time steps that are required to retain a given accuracy for a given net increment t=Nτ, and, therefore, significantly increasing the feasibility of path integral calculations. Yet another attractive feature of the present technique is that it allows for equations with singular diffusion matrices that are known to present a special problem within the scope of the path integral formalism. The favorable scaling of the fast Fourier transform is used to numerically evaluate the path integral on a grid. High efficiency is achieved due to the Stirling interpolation which dynamically readjusts the distribution function every time step with a mild increase in cost and with no loss of precision. These developments substantially improve the path integral method and extend its applicability to various time-dependent problems which are difficult to treat by other means. One can even afford to extract information on eigenvalues and eigenfunctions from a time-dependent solution thanks to the numerical efficiency of the present technique. This is illustrated by calculating the propagator and the lowest eigenvalues of a one-dimensional Fokker–Planck equation. The method is also applied to a two-dimensional Fokker–Planck equation, whose diffusion matrix does not possess an inverse (a so-called Klein-Kramers equation). The numerical applications show our method to be a dramatic improvement over the standard matrix multiplication techniques available for evaluating path integrals in that it is much more efficient in terms of speed and storage requirements.