10-year Age Class Research Articles

Elms (Ulmus L.) in the Branch “Myrhorod Forestry” of the State Specialized Forest Enterprise “Forests of Ukraine”

Introduction Elms are spread in forests, landscaping settlements, and protective forest belts. After several waves of elm mortality from Dutch elm disease (DED) in the 20th century, individual populations recovered or formed resistant hybrids. However, epiphytoties of bacterial and fungal diseases sometimes develop, particularly due to pathogen vectoring by bark beetles. In Ukraine, the spread of elms and their damage by different causes are relatively poorly investigated. This research aimed to discover the features of Ulmus sp. distribution by stand origin, age, and forest site condition in the forest fund of the Branch “Myrhorod Forestry”. Materials and Methods The data as of 2010 and 2017 on the forest fund of enterprises belonging to the Branch “Myrhorod Forestry” of the State Specialized Forest Enterprise “Forests of Ukraine” were selected from the database of Ukrainian State Forest Management Planning Association “Ukrderzhlisproekt” using SQL-query and converted to the *.xls files. Area distribution by types of forest site conditions was assessed following the Ukrainian school of forest typology. Such distributions for the entire area covered with forest vegetation, for subcompartments with elms in the stand composition, and with elms as the dominant species were compared for various elm species and stand origins, using c2-test. The percentages of stand areas of different origins and elm species in 2010 and 2017 were compared using z-test in the two proportions comparisons. The data for subcompartments with various elms as the dominant species and as a part of stands composition have been analyzed by 10-year age classes for different origins (natural and planted). The proportion of the stand area of each 10-year age class was assessed for each set of subcompartments. Then the proportion of the stands’ area, which survives up to a certain age, was evaluated. Results and Conclusions In the Branch “Myrhorod forestry”, an area of natural stands with Ulmus sp. as the dominant species for 2010–2017, and the proportion of U. minor has significantly increased. The most dramatic decrease in the survival rate of all elm species of natural stands occurred in the VI age class and planted stands in the V age class. Respective natural and planted stands were formed in the 1960s and 1970s when the peak of DED occurred in many regions. In the Branch “Myrhorod Forestry”, U. minor prefers moist fertile forest site conditions. U. laevis grows mainly in moist forest site conditions, U. pumila occurs in dry to wet habitats, U. glabra is present only in natural stands and absent in plantations. As part of stand composition, the same elm species grow in a wider range of forest site conditions than elms as the dominant species. 2 Figs., 8 Tables, 31 Refs.

The age structure of Ulmus L. stands in the eastern regions of Ukraine

The aim of the research was to determine the features of the age structure for natural and artificial elm stands depending on species, origin, and region. The proportion of the stand area of natural and artificial stands of each elm species by 10-year age classes was evaluated for the forest fund of the Donetsk, Kharkiv, and Sumy Regional Forest and Hunting Management Administrations (RFHMA). Four main forest-forming elm species are represented in the forest fund of the Donetsk and Kharkiv RFHMA (U. minor, U. laevis, U. glabra, and U. pumila). In the Sumy RFHMA, there are three forest-forming elm species: U. minor, U. laevis, and U. glabra. The maximum age of U. minor is 120, 117, and 91 years in the Donetsk, Kharkiv, and Sumy RFHMA, respectively. The mean and the maximum age of U. minor and U. glabra tends to decrease in the Donetsk – Kharkiv – Sumy RFHMA row. The proportion of U. laevis is larger in man-made plantations than in natural stands, however, in natural stands, it also increases in the Donetsk – Kharkiv – Sumy RFHMA row. U. glabra prevails in natural stands. U. pumila in the Donetsk RFHMA grows mainly in man-made plantations. A decrease in the area of newly formed U. minor stands in the Donetsk RFHMA occurred after the 1950s, and in the Kharkiv RFHMA after the 1960s in both artificial and natural stands. In the Sumy RFHMA, this also happened in the 1960s in man-made plantations. A decrease in the area of U. glabra natural and artificial stands occurred also after the 1960s. We suppose that an epiphytoty of the Dutch elm disease, well-known in Europe in the 1960s, could also be the cause of elm decline in the eastern part of Ukraine. The proportion of the stands’ area preserved up to a certain age, depends on particular elm species, region, and stand origin. However, in order to clarify the survival rate, it is necessary to consider the type of forest site conditions, the proportion of elms in the stand composition, and some other features that are to be analyzed in future research.

Effects of stand age, tree species, and climate on water table fluctuations and estimated evapotranspiration in managed peatland forests

Lowland conifer forests dominated by black spruce (Picea mariana) and tamarack (Larix laricina) typically occur in peatlands in the boreal North American forest with near-surface water tables throughout the year. These forests are ecologically and economically important resources that may be impacted by climate change. However, information characterizing effects of forest disturbance, such as even-aged harvest on water table dynamics is needed to evaluate which forest tree species cover types are most hydrologically susceptible to even-aged harvest and changes in precipitation. We used a chronosequence approach to evaluate water table fluctuations and evapotranspiration across four stand age classes (<10, 15–30, 40–80, and >100-years old) and three distinct forest cover types (productive black spruce, stagnant black spruce, and tamarack) for a period of three years in Minnesota, USA. In general, there is limited evidence for elevated water tables in the younger age classes; the <10-year age class had no significant difference in mean weekly water table depth compared to the older age classes across all cover types. Estimated actual daily evapotranspiration (ET) generally agreed with the water table observations, with the exception of the tamarack cover type where ET was significantly lower in the <10-year age class. Productive black spruce sites that are 40–80-years old had higher evapotranspiration, and lower water table, possibly reflecting increased transpiration associated with the stem exclusion stage of stand development. Tamarack in the 40-80-year age class had higher water tables but no difference in ET compared to all other age classes, indicating that other external factors are driving higher water tables in that age class. To evaluate susceptibility to changing climate, we also assessed the sensitivity and response of water table dynamics to pronounced differences in growing season precipitation that occurred across study years. In general, tamarack forests are more sensitive to changes in precipitation compared to the two black spruce forest cover types. These findings can inform expected responses of site hydrology for a range of precipitation scenarios that may occur under future climate and be used by forest managers to evaluate hydrologic impacts of forest management activities across lowland conifer forest cover types.

Rubber expansion and age-class mapping in the state of Tripura (India) 1990-2021 using multi-year and multi-sensor data.

The presentstudy focuses on the spread of rubber monoculture in the state of Tripura during past three decades (1990-2021) in the northeast region of India which is known for itsrich biodiversity, shifting cultivation, and extensive forest dynamics. Earth observation(EO) data of seven time periods from Landsat missions (1990, 1995, 2000, 2004, and2009) and Sentinel-2 (2016 and 2021) were the main source for mapping and were supplemented with MODIS-EVI temporal spectral profiles, GEDI-derived vegetation heights (2019), and Google Earth high-resolution historical images for additional cues to support discrimination, mapping, and accuracy assessment. The methodology for rubber used its unique phenology from spectral-temporal profile and multi-year comparison of patches and their dynamics for age-class mapping. The results indicate that in the state of Tripura (geographic area 1.08 Mha), the area under rubber increased from 0.3% in 1990 to 8.9% of the geographic area in 2021. The overall classification accuracy for the maps created for the years 1990, 1995, 2000, 2004, 2009, 2016, and 2021 was 84.2%, 83.9%, 84.8%, 88.0%, 86.0%, 86.7%, and 89.5%, respectively. New areas under rubber originated from various land cover classes including open forests, shifting cultivationlands, and scrub. Recent expansion has resulted in 84.3% of rubber plantations under the 10-year age class. Implications of this transformation of the natural landscape, biodiversity and biomass, and carbon pool assessment are discussed.

15-F2t-Isoprostane during the lifespan: from children to middle age

BACKGROUND AND AIM: 15-F2t-Isoprostane is a product of arachidonic acid non-enzymatic oxidation by free radicals. Validated in animal and clinical models, it is a golden standard tool for the oxidative status assessment. The aim of this study is to assess how this biomarker levels could vary during the lifespan. METHODS: The 15-F2t-Isoprostane urinary concentration was measured in 889 subjects aged between 7 and 69. The analyses were performed by ELISA kit. The levels of 15-F2t-Isoprostane were normalised by creatinine (Kinetic Jaffé method). The analysis was performed considering 10-year age classes: 10 years, 10-19 years, 20-29 years, 30-39 years, 40-49 years, 50-59 years, 60-69 years. RESULTS:The average 15-F2t-Isoprostane levels were 4.41 ± 4.69 ng/mg creatinine. The descriptive analysis reveals an apparent reduction in the age-class 11-19 years (2.78 ± 2.54 ng/mg creatinine). The average predicted values for the age classes resulting from a GLM analysis are: 10 years: 3.72 ng/mg creatinine (p0.001, 95%C.I. 2.87-4.58); 10-19 years: 2.78 ng/mg creatinine (p0.001, 95%C.I. 2.25-3.31); 20-29 years: 4.08 ng/mg creatinine (p0.001, 95%C.I. 3.04-5.12); 30-39 years 5.09 ng/mg creatinine (p0.001, 95%C.I. 4.20-5.98); 40-49 years 4.98 ng/mg creatinine (p0.001, 95%C.I. 4.35-5.60); 50-59 years: 4.28 ng/mg creatinine (p0.001, 95%C.I. 3.68-4.88) and 60-69 years: 5.23 ng/mg creatinine (p0.001, 95%C.I. 3.83-6.62). CONCLUSIONS:Oxidative stress biomarkers levels are currently studied in various populations due to their increase in pre-clinical stages of diseases that could be related to lifestyle, environmental or occupational exposures. The main evidence consists in the reduction in the concentration of 15-F2t-isoprostane in adolescence, which leads to an interruption of the constant increase in oxidative stress over the years. The knowledge of how the 15-F2t-Isoprostane levels change during the lifespan and the assessment of the trend-shape of this phenomenon are crucial to better understand the meaning of this biomarker in molecular epidemiology research. KEYWORDS: Long-term exposure, Environmental epidemiology, Molecular epidemiology

Age-Based Survival Analysis of Coniferous and Broad-Leaved Trees: A Case Study of Preserved Forests in Northern Japan

Scientifically sound methods are essential to estimate the survival of trees, as they can substantially support sustainable management of natural forest resources. Tree mortality assessments have mainly been based on forest inventories and are mostly limited to planted forests; few studies have conducted age-based survival analyses in natural forests. We performed survival analyses of individual tree populations in natural forest stands to evaluate differences in the survival of two coniferous species (Abies sachalinensis (F. Schmidt) Mast. and Picea jezoensis var. microsperma) and all broad-leaved species. We used tree rings and census data from four preserved permanent plots in pan-mixed and sub-boreal natural forests obtained over 30 years (1989–2019). All living trees (diameter at breast height ≥ 5 cm in 1989) were targeted to identify tree ages using a Resistograph. Periodical tree age data, for a 10-year age class, were obtained during three consecutive observation periods. Mortality and recruitment changes were recorded to analyze multi-temporal age distributions and mean lifetimes. Non-parametric survival analyses revealed a multi-modal age distribution and exponential shapes. There were no significant differences among survival probabilities of species in different periods, except for broad-leaved species, which had longer mean lifetimes in each period than coniferous species. The estimated practical mean lifetime and diameter at breast height values of each coniferous and broad-leaved tree can be applied as an early identification system for trees likely to die to facilitate the Stand-based Silvicultural Management System of the University of Tokyo Hokkaido Forest. However, the survival probabilities estimated in this study should be used carefully in long-term forest dynamic predictions because the analysis did not include the effects of catastrophic disturbances, which might significantly influence forests. The mortality patterns and survival probabilities reported in this study are valuable for understanding the stand dynamics of natural forests associated with the mortality of individual tree populations.

Association between socioeconomic status and physical inactivity in a general Japanese population: NIPPON DATA2010.

BackgroundLower socioeconomic status (SES) may be related to inactivity lifestyle; however, the association between SES and physical inactivity has not been sufficiently investigated in Japan.MethodsThe study population is the participants of NIPPON DATA2010, which is a prospective cohort study of the National Health and Nutrition Survey 2010 in Japan. They were residents in 300 randomly selected areas across Japan. This study included 2,609 adults. Physical activity was assessed by physical activity index (PAI) calculated from activity intensity and time. The lowest tertile of PAI for each 10-year age class and sex was defined as physical inactivity. Multivariable logistic regression analyses were conducted to examine the association of SES (employment status, educational attainment, living status, and equivalent household expenditure (EHE)) with physical inactivity.ResultsIn the distribution of PAI by age classes and sex, the highest median PAI was aged 30–39 years among men (median 38.6), aged 40–49 years among women (38.0), and median PAI was decreased with increasing age. Multivariable-adjusted model shows that not working was significantly associated with physical inactivity after adjustment for age in all age groups and sexes. Not living with spouse for adult women and elderly men was significantly associated with physical inactivity compared to those who living with spouse. However, neither educational attainment nor EHE had any significant associations with physical inactivity.ConclusionsThe result indicated that physical inactivity was associated with SES in a general Japanese population. SES of individuals need to be considered in order to prevent inactivity lifestyle.

How sick is Austria? – A decision support framework for different evaluations of the burden of disease within the Austrian population based on different data sources

ABSTRACT&#x0D; ObjectivesIn healthcare it is crucial to have a fundamental knowledge of the burden of diseases within the population. Therefore we aimed to develop an Atlas of Epidemiology to gain better insight on the epidemiological situation. Based on primary and secondary health care data, we aimed to present results in interactive charts and maps, comprehensible to experts and the general public. The atlas builds a framework for rapid deployment of new data and results in a reproducible and efficient way. As a first use case three methods based on two different databases for the estimation of diabetes prevalence in Austria are compared.&#x0D; ApproachDatasources: (i) reimbursement data 2006/2007 (GAP-DRG); (ii) national routine health survey (ATHIS) for 2006/2007. Methods for diabetes prevalence estimation: 1) ATC-ICD statistically relates pseudonymized data on medications to data on diagnoses from hospitalizations and sick leaves. 2) With the method Experts, medical experts assign specific medications to diabetes diagnoses. Patients with these medications are identified together with hospitalized diabetes diagnosed patients in GAP-DRG. 3) In ATHIS a sample of 15.000 persons was questioned if they a) ever had diabetes and b) were treated against diabetes in the last 12 months. Results are projected onto the Austrian population. Patients are divided by 10-year age-classes, gender and state. For the publicly online framework, implemented in html and javascript, pre-processed data in different granularity is required and used.&#x0D; ResultsMaps of Austria represent the prevalence of diabetes for each method and granularity level. The difference of the methods can be seen by clicking on the next map. For different age-classes (resp. different gender) the three methods can be compared directly within a bar chart. The technology for a rapid deployment of new data is now developed. For the use case first results have already been presented to decision makers, and feedback has been incorporated.&#x0D; ConclusionBesides depicting disease prevalence, the atlas of epidemiology also allows to visualize health care service data and results of simulation models in a fast and efficient way, which is important for decision makers. Soon the results of the ATC-ICD project on the prevalence of different diseases based on ICD9 diagnoses and medication data will be published in an aggregated form. This project is part of the K-Project dexhelpp in COMET – Competence Centers for Excellent Technologies that is funded by BMVIT, BMWGJ and transacted by FFG.

The Decrease in Traumatic Brain Injury Epidemics Deriving from Road Traffic Collision Following Strengthened Legislative Measures in France.

BackgroundSince 2002, France has been strengthening legislation on road traffic. This study is intended to evaluate the changes in Traumatic Brain Injury (TBI) incidence and mortality resulting from Road Traffic Collision (RTC) in the two 6-year periods before and after 2002.MethodsWe used a Registry of all RTC casualties in the Rhône Department of France. Each casualty was coded according to the Abbreviated Injury Scale (AIS). The study describes changes in demographic variables, TBI (AIS ≥ 2) incidence and mortality, other body lesions (AIS ≥ 3) associated with TBI, road user types, seatbelt and helmet wearing.FindingsRTC casualty occurrences decreased by 21% (from 64,312 to 50,746) during the period after 2002. TBI occurrence accounted for 8.6% and 6.7% of all RTC in both periods. This corresponds to a reduction of TBI casualty incidence (-42%), which was much more pronounced than RTC casualty incidence (-25%) (p < 0.0001). Severe and critical TBI (AIS-4 and -5) incidences were reduced by half as much (-21%), compared to TBI incidence. TBI mortality rate (among population) and lethality (among TBI related to RTC casualties) decreased 56% and 23%, respectively. This reduction particularly affected car occupants and victims who deceased. TBI incidence decreased 43% in all 10-year age classes until 60 on average, this decrease declining with age in the period after 2002. After adjustment for age, sex, road user types, and severity of lesions at the head and other body regions, logistic regression analysis displayed a protective effect of the period following 2002, on the risk of death after RTC-related TBI.InterpretationThe greater reductions in the incidence, severity and mortality of TBI when compared with the reduction of casualty incidence have mainly affected car users. These results should be attributable to the improvements in standards of care, primary safety of the car fleet and general road architecture safety. However, the increased reduction in the TBI epidemics in France, when compared to those observed in other developed countries for the same periods, suggests that the effects should be strongly attributable to changes in road user behaviour induced by law enforcement. The at-risk groups for TBI after RTC are now two-wheel users (motorized or not) and individuals over 60 years of age.

High Risk versus Proportional Benefit: Modelling Equitable Strategies in Cardiovascular Prevention

ObjectiveTo examine the performances of an alternative strategy to decide initiating BP-lowering drugs called Proportional Benefit (PB). It selects candidates addressing the inequity induced by the high-risk approach since it distributes the gains proportionally to the burden of disease by genders and ages.Study Design and SettingMild hypertensives from a Realistic Virtual Population by genders and 10-year age classes (range 35–64 years) received simulated treatment over 10 years according to the PB strategy or the 2007 ESH/ESC guidelines (ESH/ESC). Primary outcomes were the relative life-year gain (life-years gained-to-years of potential life lost ratio) and the number needed to treat to gain a life-year. A sensitivity analysis was performed to assess the impact of changes introduced by the ESH/ESC guidelines appeared in 2013 on these outcomes.ResultsThe 2007 ESH/ESC relative life-year gains by ages were 2%; 10%; 14% in men, and 0%; 2%; 11% in women, this gradient being abolished by the PB (relative gain in all categories = 10%), while preserving the same overall gain in life-years. The redistribution of benefits improved the profile of residual events in younger individuals compared to the 2007 ESH/ESC guidelines. The PB strategy was more efficient (NNT = 131) than the 2013 ESH/ESC guidelines, whatever the level of evidence of the scenario adopted (NNT = 139 and NNT = 179 with the evidence-based scenario and the opinion-based scenario, respectively), although the 2007 ESH/ESC guidelines remained the most efficient strategy (NNT = 114).ConclusionThe Proportional Benefit strategy provides the first response ever proposed against the inequity of resource use when treating highest risk people. It occupies an intermediate position with regards to the efficiency expected from the application of historical and current ESH/ESC hypertension guidelines. Our approach allows adapting recommendations to the risk and resources of a particular country.

Estimated and reported incidence of pertussis in Estonian adults: A seroepidemiological study

ObjectivesRates of pertussis immunisation among children in Estonia are high (∼95%), but pertussis is still the most common vaccine preventable childhood disease. Adults are suspected to be sources of pertussis in children. We aimed to measure pertussis toxin (PT) IgG in adults to estimate pertussis infection activity and compare estimated and reported pertussis incidences. MethodsIn a cross-sectional serosurvey, consecutive leftover blood sera (n=3327) from subjects aged 20–99 years old were collected at Quattromed HTI laboratories between the 7th January and 27th February 2013. Anti-PT IgG concentration was measured by ELISA (Euroimmun, Lübeck, Germany). Estimated annual pertussis incidence was calculated for 10-year age classes using de Melker et al. (2006. J Infect. 53(2):106–13) formula. ResultsThe mean number of samples in each 10-year age class was 466 (SD 20.5), except for 90–99 year olds which contained 65 samples.More than half of all subjects (58.1%) had anti-PT IgG <5.0IU/mL, 2.7% had 62.5 to <125IU/mL and 0.6% ≥125IU/mL; no differences occurred between 10-year age classes.Estimated incidence of pertussis infection was 5.8% (95% CI 4.8–7.0) in 2012, with peaks observed in 20–29 year olds (11.0%; 95% CI 7.4–15.6) and 90–99 year olds (10.8%; 95% CI 3.0–26.2). Estimated pertussis incidence rate was 915 times higher than reported.Of 80 subjects with anti-PT IgG ≥62.5IU/mL, 25 (31.3%) had complained of coughing to their GP during the previous six months. ConclusionThe frequency of pertussis infection was similar for all ages, suggesting similar Bordetella pertussis activity in adults and children. The wide gap between reported and estimated incidence indicates poor recognition of pertussis, likely owing to it being an asymptomatic or mild disease.

Estimates of lifetime attributable risk of cancer after a single radiation exposure from 64-slice computed tomographic coronary angiography

AimsTo estimate the life attributable risk (LAR) of cancer incidence over a wide range of dose radiation exposure and a large spectrum of possible diagnostic computed tomographic coronary angiography (CTCA)...

Irritable bowel syndrome is more frequent in patients hospitalized for ischaemic colitis: results of a case–control study

It has been suspected that there is an epidemiological link between irritable bowel syndrome (IBS) and ischaemic colitis (IC). We performed a retrospective case-control study to compare the frequency of IBS in patients hospitalized for IC compared with that of patients with peptic ulcer bleeding. Cases were patients with a first episode of IC and controls were patients with a first episode of peptic ulcer bleeding, matched to cases for sex and 10-year age-class. Diagnosis of IBS was based on medical information extracted from hospital medical files and a standard self-questionnaire. The association between IBS and IC was tested using Mc Nemar's paired odds ratio (OR); confidence interval at 95% (CI 95%) was calculated; Mantel-Haenzel's Chi(2) was applied. A total of 113 cases and 113 matched controls were studied. There were 37 males and 76 females and the mean age was 69 +/- 15 years in each group. The prevalence of IBS in cases was 16.9%vs 1.8% in controls. The risk of IBS was 11.05 times higher among cases than in controls (P < 0.001); CI 95%: (2.45-49.74). A total of 87 pairs with complete data were used for OR calculation. The risk of IBS was 7.5 times higher in cases than in controls (P = 0.002); CI 95%: (1.72-32.80). This case-control study shows that IBS is more frequent in IC patients than in controls.

The Fire in the East

The Fire in the East

Traffic-Related Air Pollution in Relation to Incidence and Prognosis of Coronary Heart Disease

Long-term air pollution exposure is associated with increased mortality, but the association with incidence of fatal and nonfatal coronary heart disease is less certain. Moreover, it is unknown how chronic exposure to air pollution affects prognosis among survivors of a first coronary event. This study evaluated the association between long-term traffic-related air pollution exposure and incidence of nonfatal and fatal coronary events, as well as subsequent hospital readmission and mortality among myocardial infarction survivors. The study population comprised all residents of Rome aged 35-84 years during the period 1998-2000. Residential nitrogen dioxide (NO2) exposure as a marker of traffic pollution was assessed by a land-use regression model in 1995-1996 (R = 0.69). A total of 11,167 incident coronary events were observed (4654 fatal, including 3598 out-of-hospital coronary deaths, and 6513 nonfatal). The cohort of 6513 survivors was followed 4.0-7.5 years for readmission or mortality, starting 28 days from the date of first event. Relative risks per 10 mug/m of NO2 exposure, adjusted for age, sex, and socioeconomic status, were calculated by Poisson regression (population-based incidence) and Cox regression (cohort analysis). The relative risk for incidence in coronary events per 10 mug/m of NO2 was 1.03 (95% confidence interval = 1.00-1.07). Stronger associations were found for fatal cases (1.07; 1.02-1.12) and out-of-hospital deaths (1.08; 1.02-1.13). Using NO2 exposure at the time of the first event, there was no association of air pollution exposure with either subsequent hospital readmission or mortality among survivors of the first coronary event. Long-term air pollution exposure increases the risk of coronary heart disease, particularly fatal events. Hospital readmission or subsequent mortality among survivors was not associated with traffic air pollution.

Effect of age on the relationship between gastric cancer and Helicobacter pylori. Tokyo Research Group of Prevention for Gastric Cancer.

Helicobacter pylori is thought to be involved in the pathogenesis of gastric cancer, but the time point at which it produces its effects (critical time) is unknown. We measured the serum level of H. pylori antibody in 787 gastric cancer patients and 1007 controls aged 20 to 69. Odds ratios for different gastric cancer types and stages were determined for each 10‐year age class. The overall odds ratio for gastric cancer decreased with age, being 7.0 for those aged 20–29, 14.5 for those aged 30–39, 9.1 for those aged 40–49, 3.5 for those aged 50–59, and 1.5 for those aged 60–69 (trend in odds ratios: P < 0.01). However, there was no such age‐dependent trend for early diffuse‐type cancer; the odds ratios were 12.6, 4.0, 7.2, 6.5, and 18.5 respectively (P=0.29). Early cancer tended to show higher seroprevalence than advanced cancer, especially in older subjects. No significant difference in seroprevalence was observed between diffuse and intestinal cancers within each age‐class. Seroreversion must have occurred in the time interval between the critical time and the diagnosis of the cancer, especially in older patients. The age‐dependent relationship between H. pylori and gastric cancer may be due to seroreversion, which itself may be independent of age. This age‐independence indicates that prolonged exposure to H. pylori does not increase the magnitude of its influence on gastric carcinogenesis. Possible mechanisms through which H. pylori exerts pathogenic effects are continuous inflammation in adulthood and/or irreversible damage to gastric mucosa in childhood or the teenage years.

Past occupational exposure to asbestos among men in France.

This study aimed at reconstructing changes in the frequency and levels of occupational asbestos exposure in France over the past century. Work histories were collected during 11 population-based case-referent studies recently carried out in France, and an asbestos-specific job-exposure matrix including 10 625 jobs was used to estimate indices of past occupational asbestos exposure. The results were estimated from a sample of 4287 subjects, bootstrapped 200 times. The distribution of socioeconomic categories within the sample was compared with that of the general population in 1954, 1962, 1968, 1975, and 1982. The proportion of blue-collar workers was similar. The highest proportion of exposed subjects was found between 1950 and 1980. Around 10% of each 10-year age class was exposed to asbestos. For those born in 1930-1939, 15.2% was exposed between the ages of 20 and 29 years. For each age class born in 190-1939, the proportion exposed at least once by 60 years of age ranged from 18.2% to 24.5 % and, of those exposed, the cumulative duration of exposure ranged from 11.3 to 15.4 years by the age of 60 years. A population exposure index showed that the heaviest exposure occurred between 1960 and 1970 and that the age classes born between 1920 and 1929 were the most heavily exposed. Time trends showed that the mean value of this index for the men aged 20-59 years reached a peak in the 1960s and then decreased. This study presents data of reasonable validity about occupational asbestos exposure in France and its trends over the past century; the data are being used to forecast the development of male mortality from mesothelioma in France.

Balance and Sustainability in Multiaged Stands: A Northern Conifer Case Study

Abstract Classical silvicultural concepts of balance and sustainability in selection stands are examined using a 40-year case study in a mixed hemlock-spruce-fir stand. Although the stand initially conformed well to the target structure, deficits of poletimber and surpluses of sawtimber have since developed. Viewing stand structure in terms of area occupied by 10-year age classes, in addition to the diameter distribution, reveals important structural and species imbalances and suggests future management directions.

Natural disturbance and gap phase dynamics in southern Appalachian spruce–fir forests

Spatially small canopy gaps dominated the natural disturbance regime of old-growth spruce–fir forests in the Great Smoky Mountains, North Carolina and Tennessee. New gaps ≤200 m2 in size were formed with a frequency of 0.006 to 0.009/year and the 1- to 10-year age class of these gaps covered an estimated 6 to 17% of the study area (depending on calculation method). Sixty canopy gaps sampled on a 7-ha intensive study site ranged in size from 15 to 150 m2. Although tree replacement patterns in these gaps were unpredictable from gap size and age, the gap event was important in species interactions. The three canopy dominants, Abiesfraseri (Pursh) Poir., Picearubens Sarg., and Betulalutea Michx.f., had unique suites of life history traits. Abies reached high understory densities, but had the highest canopy turnover rate of the three species. Betula was scarce in the understory, but had a crown expansion rate in gaps eight times that of the two conifers. Picea was the longest lived species and appeared to have the best survivorship. Tree replacement models based on advanced regeneration led to the prediction that Abies canopy density would increase and Betula canopy density would decrease, while models based on gap inventories led to opposite conclusions. Data from direct observation of the gap capture process supported the hypothesis that this old-growth stand was near compositional equilibrium and underscored the importance of disturbance effects in community organization.

Carbon storage patterns in Douglas-fir ecosystems

An ecosystem-level carbon cycling model, coupled with estimates of forested land area classified in 10-year age classes, was used to simulate regional net carbon storage in young Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) ecosystems in western Oregon and Washington. The age-specific net carbon storage patterns were similar in 1934 and 1980, but total carbon storage was 1268 × 103 Mg more in 1980 than in 1934. Net carbon release was predicted for the first 15–20 years of forest development, because of decomposition of detritus and soil organic matter following harvest. This may vary between 10 and 30 years at specific sites with higher or lower actual evapotranspiration (AET) rates, respectively, than the regional average. Calculations of annual carbon storage based on tree biomass alone exceeded estimates calculated from the simulation by 1–2 Mg C•year−1.