SummaryWe researched epidemiologic associations between environmental and demographic factors and prevalence of Helicobacter pylori infection in a suburban Jamaican community. Using a clustered sampling technique, 22 domestic yards enclosing 60 separate households were randomly selected from a local community. All household members (n ϭ 346) were invited to participate following informed consent; the overall compliance rate was 58.9%. A commercial enzyme immunoassay (HM·CAP) was used to detect IgG antibodies raised against H. pylori. Environmental and demographic information was obtained by questionnaire. The seroprevalence of H. pylori was 69.9% (n ϭ 202). Analysis of the independent variables revealed three major components: Component 1 described, collectively, good personal hygiene and sanitation, indoor water supply and absence of straying animals in the peridomestic area; Component 2 included older age, good personal hygiene and large yard size; Component 3 the presence of domestic animals (cats and dogs) and, again, large yard size. These three complexes explained 42.2% of the variability in the data set. Logistic regression showed that Components 2 and 3 were independently associated with H. pylori seropositivity, indicating that a combination of demographic, environmental and zoonotic factors is involved in the spread of H. pylori infections at the tropical community level.
Crop tree release (CTR) can be an effective intermediate silvicultural treatment for culturing high-value stems in mixed hardwood stands. The lengthy rotation of hardwoods requires long-term evaluations if silvicultural treatment effectiveness is to be fully evaluated. Our study provides a 35-year evaluation of individual-tree and stand response to CTR imposed in small sawtimber-sized white-oak (Quercus alba L.)-dominated stands. The focus on white oak is justified based on the significant biologic and economic values of the species, and this study furthers our ability to optimize use of CTR as management tool for sustaining our oak resources. The replicated experiment included three treatment levels: 20 crop trees ac−1, 34 crop trees ac−1, and a control. Using a repeated-measures framework, we analyzed (1) how CTR affects growth and stem quality of white oak crop trees and (2) stand-level effects of CTR on basal area, stocking, and ingrowth. CTR increased crop tree diameter growth and proportion of crop trees reaching their maximum potential grade. However, crop tree diameter growth and proportion achieving maximum potential grade did not differ between the 20 and 34 crop trees ac−1 treatments. Finally, CTR stimulated stand-wide growth without altering the patterns of ingrowth density or species distributions.
Study Implications: Crop tree release was applied to 70- to 80-year-old white-oak (Quercus alba L.)-dominated stands with positive crop tree growth and quality outcomes. Beneficial implications were observed at the crop-tree-level and stand-level when either 20 or 34 crop trees ac−1 were treated using a four-sided, crown-touching release. Although crop tree release has been extensively examined for red oak (Quercus section Lobatae), our results identify this treatment’s utility in mid- to late-rotation white oak stands and provide a silvicultural basis for applying the practice in the context of contemporary concerns over white oak sustainability.
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