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PubMed1982

Tuberculosis in wildlife in the Ruwenzori National Park Uganda (part I).

The technique adopted for a survey of tuberculous infection in wild Cape buffalo (Syncerus caffer, Sparrman) living in the Ruwenzori National Park, Uganda is described and the results of gross post-mortem examinations of a random sample of 52 buffalo and a selected sample of 64 thin buffalo are tabulated. Tuberculosis was found to occur in buffalo in the area of the Park north of the Maramagambo Forest; the disease is considered to be absent from the area south of the forest. Tuberculosis was found to affect 10% of the random sample of buffalo and 38% of the selected thin sample. Laboratory procedures carried out for the isolation and typing of the mycobacteria are described. Mycobacterium bovis was shown to be responsible for 12 of 14 infections and atypical mycobacteria for the remaining two. The distribution and character of the lesions are described and an account of the epidemiology, morbidity and mortality of the disease is given. It is estimated that tuberculosis is responsible for an annual mortality of about 1% of the 18,000 buffalo inhabiting the Park.

Animals↗

PubMed2003

Clonal diversity and genetic differentiation in Ilex leucoclada M. patches in an old-growth beech forest.

We investigated clonal diversity within patches of Ilex leucoclada and genetic variation within and among patches using random amplified polymorphic DNA (RAPD) markers in a 1-ha plot within an old-growth beech forest. We found 38 patches that exhibited a clumped distribution in the middle of the plot. We identified a total of 166 RAPD phenotypes among the 215 stems sampled from 27 patches that were completely within the plot. The population showed high clonal diversity within patches (mean number of genets relative to number of stems = 0.79; mean Simpson's D = 0.89). Variation in RAPD phenotypes among patches was highly significant (PhiST in the molecular variance analysis = 0.316, P < 0.001), indicating genetic differentiation among patches. Pairwise genetic distances, PhiST, among patches did not correlate with geographical distances among patches. The cluster analysis based on the genetic distances showed few clear clusters of patches, indicating no spatial genetic structure among patches. High levels of clonal diversity both within patches and within the population may be explained by multiple founders, seedling recruitment during patch-formation, and somatic mutation. The significant genetic differentiation among patches may be caused by separate founding events and/or kin structuring within patches.

Cluster Analysis↗

PubMed2026

Effect of Peer Comparison Feedback and Professional Norms on Vitamin D Testing and Generic Medication Prescribing.

BACKGROUND: Organization for Economic Cooperation and Development (OECD) estimates suggest that 20% of health care spending is wasteful or even harmful. Previous interventions have had limited success in discouraging low-value care in medical practice. METHODS: We conducted a nationwide randomized controlled trial among primary care physicians (PCPs) in Switzerland (November 2020-December 2021). We randomly assigned PCPs to one of three intervention groups related to low-value care (vitamin D testing, generic prescribing, or a cost intervention) or a control group. This article reports results for the vitamin D testing and generic prescribing interventions compared with the common control group. PCPs in the intervention groups received a personalized information letter combining professional norms and peer comparison feedback about the low-value service (either vitamin D testing or prescribing of nongeneric medications). Primary endpoints were (1) the number of vitamin D tests per 100 patients and (2) the share of generic medications prescribed. We estimated average treatment effects using linear regression and assessed effect heterogeneity with a causal forest. RESULTS: A total of 618 PCPs were randomly assigned to the vitamin D intervention, 597 to the generic prescribing intervention and 601 to the common control group. The intervention reduced average vitamin D testing by 3.66 tests per 100 patients (95% confidence interval [CI], -5.42 to -1.89; P<0.001). The intervention did not increase average generic medication prescribing (mean difference, +0.57 percentage points; 95% CI, -0.68 to +1.81 percentage points; P=0.37). Heterogeneity analysis suggested that reductions in vitamin D testing among physician subgroups ranged from one to seven per 100 patients and that higher baseline generic prescribing rates were associated with increases in generic substitution following the intervention. No increases in low-value care were seen among those physicians with low baseline levels. CONCLUSIONS: Peer comparison letters emphasizing professional norms reduced vitamin D testing but did not increase generic medication prescribing. (Funded by the Swiss National Science Foundation; AEA Randomized Controlled Trials Registry no., AEARCTR-0004747.).

Humans↗

PubMed2000

Species-area curves, spatial aggregation, and habitat specialization in tropical forests.

The relationship between species diversity and sampled area is fundamental to ecology. Traditionally, theories of the species-area relationship have been dominated by random-placement models. Such models were used to formulate the canonical theory of species-area curves and species abundances. In this paper, however, armed with a detailed data set from a moist tropical forest, we investigate the validity of random placement and suggest improved models based upon spatial aggregation. By accounting for intraspecific, small-scale aggregation, we develop a cluster model which reproduces empirical species-area curves with high fidelity. We find that inter-specific aggregation patterns, on the other hand, do not affect the species-area curves significantly. We demonstrate that the tendency for a tree species to aggregate, as well as its average clump size, is not significantly correlated with the species' abundance. In addition, we investigate hierarchical clumping and the extent to which aggregation is driven by topography. We conclude that small-scale phenomena such as dispersal and gap recruitment determine individual tree placement more than adaptation to larger-scale topography.

Ecology↗

PubMed1991

Respiratory symptoms among elderly people in the New Forest area as assessed by postal questionnaire.

This study was carried out to estimate the prevalence of respiratory symptoms among people aged 65 years and older and assess the value of a postal survey in obtaining this information. A questionnaire was sent to 2011 subjects (957 men) drawn by age-stratified random sampling from the age-sex registers of four New Forest group practices (1:3.3 sample). A total of 1803 replied, a 96.2% response after excluding 136 who had died or moved from the area. The accuracy of replies was verified for 355 (20%) randomly selected subjects. Forty per cent had no respiratory symptoms. Exertional breathlessness was common (38%), increasing in prevalence with age but not with smoking history, and was the only symptom reported by 10% of subjects. Only 14.2% were current smokers; more of the subjects aged 85 years and over were lifelong non-smokers. Two hundred and ninety-six (16.4%) had chronic bronchitis, which was more common among smokers; 151 (8.4%) gave a history of asthma, of whom half (76) had active asthma, which was slightly less common among the very elderly subjects. Only 489 (27.1%) of subjects had seen their doctors with chest symptoms during the preceding 2 years.

Age Factors↗

PubMedDate not supplied

Identifying riparian sinks for watershed nitrate using soil surveys.

The capacity of riparian zones to serve as critical control locations for watershed nitrogen flux varies with site characteristics. Without a means to stratify riparian zones into different levels of ground water nitrate removal capacity, this variability will confound spatially explicit source-sink models of watershed nitrate flux and limit efforts to target riparian restoration and management. We examined the capability of SSURGO (1:15 840 Soil Survey Geographic database) map classifications (slope class, geomorphology, and/or hydric soil designation) to identify riparian sites with high capacity for ground water nitrate removal. The study focused on 100 randomly selected riparian locations in a variety of forested and glaciated settings within Rhode Island. Geomorphic settings included till, outwash, and organic/alluvial deposits. We defined riparian zones with "high ground water nitrate removal capacity" as field sites possessing both >10 m of hydric soil width and an absence of ground water surface seeps. SSURGO classification based on a combination of geomorphology and hydric soil status created two functionally distinct sets of riparian sites. More than 75% of riparian sites classified by SSURGO as organic/alluviumhydric or as outwash-hydric had field attributes that suggest a high capacity for ground water nitrate removal. In contrast, >85% of all till sites and nonhydric outwash sites had field characteristics that minimize the capacity for ground water nitrate removal. Comparing the STATSGO and SSURGO databases for a 64000-ha watershed, STATSGO grossly under-represented critical riparian features. We conclude that the SSURGO database can provide modelers and managers with important insights into riparian zone nitrogen removal potential.

Data Collection↗

PubMed2001

Mollusks of Manuel Antonio National Park, Pacific Costa Rica.

The mollusks in Manuel Antonio National Park on the central section of the Pacific coast of Costa Rica were studied along thirty-six transects done perpendicular to the shore, and by random sampling of subtidal environments, beaches and mangrove forest. Seventy-four species of mollusks belonging to three classes and 40 families were found: 63 gastropods, 9 bivalves and 2 chitons, during this study in 1995. Of these, 16 species were found only as empty shells (11) or inhabited by hermit crabs (5). Forty-eight species were found at only one locality. Half the species were found at one site, Puerto Escondido. The most diverse habitat was the low rocky intertidal zone. Nodilittorina modesta was present in 34 transects and Nerita scabricosta in 30. Nodilittorina aspera had the highest density of mollusks in the transects. Only four transects did not clustered into the four main groups. The species composition of one cluster of transects is associated with a boulder substrate, while another cluster of transects associates with site. Two clusters were not associated to any of the factors recorded. Some species were present in previous studies but absent in 1995, while others were absent in the previous studies but found in 1995. For example, Siphonaria gigas was present in 1995 in many transects with a relatively high density, but absent in 1962, probably due to human predation before the establishment of the park. Including this study, a total of 97 species of mollusks in three classes and 45 families have been reported from Manuel Antonio National Park. Sixty-nine species are new reports for the area: 53 gastropods, 14 bivalves and 2 chitons. There are probably more species of mollusks at Manuel Antonio National Park, than the 97 reported here, because some areas have not been adequately sampled (e.g., deep environments) and many micro-mollusks could not be identified.

Animals↗

PubMed2006

Measuring effectiveness of dietetic interventions in child obesity: a systematic review of randomized trials.

OBJECTIVES: To assess the effectiveness of dietetic treatment for obese children and to report details of dietary interventions. DATA SOURCES: English-language articles from 1975 to 2003 available from health and medical databases. STUDY SELECTION: Randomized controlled trials with subjects younger than 18 years of age that included a dietary intervention in isolation or in combination with lifestyle modifications and/or psychological therapies. One person searched the databases; 2 people independently critically appraised the articles for methodological quality and then extracted data using standardized tools. DATA EXTRACTION: Thirty-seven randomized controlled trials met the inclusion criteria; 17 contained sufficient information for a Forest plot of the standardized effects. Eight studies had a true control and were included in a meta-analysis. The random effects model was reported if the Q noncombinability chi(2) statistic was significant at the 10% level because it has low power as a strict test of homogeneity. DATA SYNTHESIS: The 2 strongly qualified meta-analyses suggest that interventions that include a dietary treatment do achieve relative weight loss. Details of the dietary intervention or participant food intake are rarely described. CONCLUSIONS: It is not possible to evaluate the effectiveness of dietary treatment for childhood obesity because of the lack of high-quality studies and the heterogeneity of designs, treatment combinations, outcome measures, and follow-up. There is an urgent need to improve the quality of studies in this area because childhood obesity poses major health risks for populations, yet there is limited evidence on which to base treatment strategies.

Adolescent↗

PubMed2005

Epidemiology of forest malaria in central Vietnam: a large scale cross-sectional survey.

In Vietnam, a large proportion of all malaria cases and deaths occurs in the central mountainous and forested part of the country. Indeed, forest malaria, despite intensive control activities, is still a major problem which raises several questions about its dynamics.A large-scale malaria morbidity survey to measure malaria endemicity and identify important risk factors was carried out in 43 villages situated in a forested area of Ninh Thuan province, south central Vietnam. Four thousand three hundred and six randomly selected individuals, aged 10-60 years, participated in the survey. Rag Lays (86%), traditionally living in the forest and practising "slash and burn" cultivation represented the most common ethnic group. The overall parasite rate was 13.3% (range [0-42.3] while Plasmodium falciparum seroprevalence was 25.5% (range [2.1-75.6]). Mapping of these two variables showed a patchy distribution, suggesting that risk factors other than remoteness and forest proximity modulated the human-vector interactions. This was confirmed by the results of the multivariate-adjusted analysis, showing that forest work was a significant risk factor for malaria infection, further increased by staying in the forest overnight (OR= 2.86; 95%CI [1.62; 5.07]). Rag Lays had a higher risk of malaria infection, which inversely related to education level and socio-economic status. Women were less at risk than men (OR = 0.71; 95%CI [0.59; 0.86]), a possible consequence of different behaviour. This study confirms that malaria endemicity is still relatively high in this area and that the dynamics of transmission is constantly modulated by the behaviour of both humans and vectors. A well-targeted intervention reducing the "vector/forest worker" interaction, based on long-lasting insecticidal material, could be appropriate in this environment.

Adolescent↗

PubMed2003

Partitioning interannual variability in net ecosystem exchange between climatic variability and functional change.

Interannual variability (IAV) in net ecosystem exchange of carbon (NEE) is a critical factor in projections of future ecosystem changes. However, our understanding of IAV is limited because of the difficulty in isolating its numerous causes. We proposed that IAV in NEE is primarily caused by climatic variability, through its direct effects on photosynthesis and respiration and through its indirect effects on carbon fluxes (i.e., the parameters that govern photosynthesis and respiration), hereafter called functional change. We employed a homogeneity-of-slopes model to identify the functional change contributing to IAV in NEE and nighttime ecosystem respiration (RE). The model uses multiple regression analysis to relate NEE and RE with climatic variables for individual years and for all years. If the use of different slopes for each year significantly improves the model fitting compared to the use of one slope for all years, we consider that functional change exists, at least on annual time scales. With the functional change detected, we then partition the observed variation in NEE or RE to four components, namely, the functional change, the direct effect of interannual climatic variability, the direct effect of seasonal climatic variation, and random error. Application of this approach to a data set collected at the Duke Forest AmeriFlux site from August 1997 to December 2001 indicated that functional change, interannual climatic variability, seasonal climatic variation and random error explained 9.9, 8.9, 59.9 and 21.3%, respectively, of the observed variation in NEE and 13.1, 5.0, 38.1 and 43.8%, respectively, of the observed variation in RE.

Carbon Dioxide↗

PubMed2005

Hand-arm vibration syndrome (HAVS) and musculoskeletal symptoms in the neck and the upper limbs in professional drivers of terrain vehicles--a cross sectional study.

This study compares the prevalence of symptoms of Hand-arm vibration syndrome (HAVS) and musculoskeletal symptoms in the neck and the upper limbs, between professional drivers of terrain vehicles and a referent group. 769 male professional drivers of forest machines, snowmobiles, snowgroomers and reindeer herders and 296 randomly selected male referents completed a questionnaire about symptoms of HAVS and musculoskeletal symptoms in the neck and the upper limbs. They also gave information about their lifetime exposure duration driving terrain vehicles and their nicotine use. Prevalence odds ratios (POR) were determined and adjusted for age and nicotine use. Results show that there is a relation between exposure to driving terrain vehicles and some of the symptoms of HAVS (POR: 1.2-6.1). Increased odds of musculoskeletal symptoms in neck, shoulders and wrists were also found (POR 1.2-6.4), and it seemed to be related to the cumulative exposure time.

Adult↗

PubMed1996

Genetic exchange as a possible source of genomic diversity in sylvatic populations of Trypanosoma cruzi.

Thirty six stocks of Trypanosoma cruzi isolated from sylvatic mammals (32 Didelphis marsupialis and one Philander opossum) and triatomine bugs (Rhodnius robustus and one unidentified bug) in the Amazonian forest by Carajas, Brazil were characterized by isoenzyme and random amplified polymorphic DNA (RAPD) analysis as belonging to principal zymodeme '1 (Z1). Two different homozygous phenotypes and the corresponding heterozygous phenotype were found for phosphoglucomutase with an observed frequency almost identical with that predicted by the theoretical Hardy-Weinberg distribution. Parental and hybrid profiles were also suggested by RAPD analysis, which allowed exclusion of mixed parental strains from the hybrids: isoenzyme and RAPD profiles of biological clones were also indistinguishable from those of uncloned stocks. Trypanosoma cruzi stocks from widely separated geographic origins in Central and South America gave similar RAPD profiles that allowed them to be recognized as being Z1. These results indicate that genetic exchange could contribute to the generation of genetic diversity during the sylvatic cycle of T. cruzi, and this may have epidemiologic and taxonomic implications.

Animals↗

PubMed2001

A randomized, blinded, controlled trial investigating the gastrointestinal health effects of drinking water quality.

A double-blinded, randomized, controlled trial was carried out in in Melbourne, Australia, to determine the contribution of drinking water to gastroenteritis. Melbourne is one of the few major cities in the world that draws drinking water from a protected forest catchment with minimal water treatment (chlorination only). Six hundred families were randomly allocated to receive either real or sham water treatment units (WTUs) installed in their kitchen. Real units were designed to remove viruses, bacteria, and protozoa. Study participants completed a weekly health diary reporting gastrointestinal symptoms during the 68-week observation period. There were 2,669 cases of highly credible gastroenteritis (HCG) during the study (0.80 cases/person/year). The ratio of HCG episode rates for the real WTU group compared to the sham WTU group was 0.99 (95% confidence interval, 0.85-1.15, p = 0.85). We collected 795 fecal specimens from participants with gastroenteritis, and pathogens were not more significantly common in the sham WTU group. We found no evidence of waterborne disease in Melbourne. The application of this methodology to other water supplies will provide a better understanding of the relationship between human health and water quality.

Adult↗

PubMed2002

A quantification of predation rates, indirect positive effects on plants, and foraging variation of the giant tropical ant, Paraponera clavata.

While a clear consensus is emerging that predators can play a major role in shaping terrestrial communities, basic natural history observations and simple quantifications of predation rates in complex terrestrial systems are lacking. The potential indirect effect of a large predatory ant, Paraponera clavata Fabricius (Formicidae: Ponerinae), on herbivores was determined on rainforest trees at La Selva Biological Station in Costa Rica and Barro Colorado Island in Panama. Prey and other food brought back to nests by 75 colonies of P. clavata were quantified, taking into account temporal, seasonal, and microhabitat variation for both foraging activity and composition of foraging booty. The dispersion and density of ant colonies and combined density with the mean amounts of prey retrieval were used to calculate rates of predation per hectare in the two forests. In addition, herbivory was measured on trees containing P. clavata and on trees where the ants were not foraging. Colonies at La Selva brought back significantly more nectar plus prey than those at Barro Colorado Island, but foraging patterns were similar in the two forests. At both forests, the ants were more active at night, and there was no significant seasonal or colonial variation in consumption of nectar, composition of foraging booty, and overall activity of the colonies. At La Selva, trees containing P. clavata colonies had the same levels of folivory as nearest neighbor trees without P. clavata but had significantly lower folivory than randomly selected trees. Predation by this ant was high in both forests, despite its omnivorous diet. This insect predator is part of potentially important top-down controls in these wet and moist forests.

Animals↗

PubMed2000

Exploring the Phylogenetic Structure of Ecological Communities: An Example for Rain Forest Trees.

Because of the correlation expected between the phylogenetic relatedness of two taxa and their net ecological similarity, a measure of the overall phylogenetic relatedness of a community of interacting organisms can be used to investigate the contemporary ecological processes that structure community composition. I describe two indices that use the number of nodes that separate taxa on a phylogeny as a measure of their phylogenetic relatedness. As an example of the use of these indices in community analysis, I compared the mean observed net relatedness of trees (≥10 cm diameter at breast height) in each of 28 plots (each 0.16 ha) in a Bornean rain forest with the net relatedness expected if species were drawn randomly from the species pool (of the 324 species in the 28 plots), using a supertree that I assembled from published sources. I found that the species in plots were more phylogenetically related than expected by chance, a result that was insensitive to various modifications to the basic methodology. I tentatively infer that variation in habitat among plots causes ecologically more similar species to co-occur within plots. Finally, I suggest a range of applications for phylogenetic relatedness measures in community analysis.

net ecological similarity↗

PubMed2000

Spatial patterns in the distribution of tropical tree species.

Fully mapped tree census plots of large area, 25 to 52 hectares, have now been completed at six different sites in tropical forests, including dry deciduous to wet evergreen forest on two continents. One of the main goals of these plots has been to evaluate spatial patterns in tropical tree populations. Here the degree of aggregation in the distribution of 1768 tree species is examined based on the average density of conspecific trees in circular neighborhoods around each tree. When all individuals larger than 1 centimeter in stem diameter were included, nearly every species was more aggregated than a random distribution. Considering only larger trees (>/= 10 centimeters in diameter), the pattern persisted, with most species being more aggregated than random. Rare species were more aggregated than common species. All six forests were very similar in all the particulars of these results.

Central America↗

PubMed2002

Distribution, survivorship and mortality sources in immature stages of the neotropical leaf miner Pachyschelus coeruleipennis Kerremans (Coleoptera: Buprestidae).

Distribution, sources of mortality, and survivorship of immatures was investigated during the reproductive season of the neotropical buprestid leaf miner, Pachyschelus coeruleipennis, that burrows in leaves of Croton floribundus (Euphorbiaceae) in SE, Brazil. Immature distribution was investigated by a random sample of 120 shrubs of C. floribundus growing along forest edges. Marked leaves were followed to recorded sources of mortality and survivorship of immature stages. Females lay their eggs preferentially in the young leaves of the host plant, with mines and pupal cells having been found on the middle part of plants. Densities of eggs, active mines, and pupal cells were, respectively, 25 +/- 2, 6 +/- 1, and 1 +/- 0.3 per 100 leaves. Predators and parasitoids accounted for the majority of losses in the immature P. coeruleipennis population. Mortality was 3 times lower in the egg stage than in the last larval instar. Predation rate was greater than parasitism but the latter increased much more during the development of immatures. Survivorship and sources of mortality were different between early and late season sample of leaf-miner immatures. Parasitism rate was greater in the late-season whereas predation was greater in early-season samples. These results are compared with mortality patterns described for other buprestid leaf miners in temperate and tropical regions.

Animals↗

PubMed1999

[High allozyme variation in populations of three spiny rat species from Upper Amazonia: association with ecology and evolution].

The allozyme variation in three spiny rat species of the genus Proechimys from Upper Amazonia was studied in relation to their ecology and evolution. The ecological environmental factors and biotopic distribution of species were analyzed. The unusually high allozyme variation was found in P. simonsi and P. sp. (2n = 34) inhabiting native forest biotopes. A relatively low allozyme variation in P. brevicauda was assumed to be associated with eurybiotic properties and the ability of this species to adapt to anthropogenic biotopes. Data on chromosome homeology and reconstruction of chromosome rearrangements in six spiny rat species were correlated with allozyme variation. The results suggested that chromosome rearrangements played the major role in evolution of the spiny rat species, and that the reorganization of the P. brevicauda genome was not random. P. simonsi and P. sp. (2n = 34), which live in native forest biotopes and carry an excessive genomik "informational load", were assumed to be highly susceptible to any novel external factors. These species are potentially able to produce new chromosome forms and are most significantly affected by deforestation.

Animals↗