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  1. Article ; Online: The relationship between depression symptoms and academic performance among first-year undergraduate students at a South African university: a cross-sectional study.

    Wagner, F / Wagner, R G / Kolanisi, U / Makuapane, L P / Masango, M / Gómez-Olivé, F X

    BMC public health

    2022  Volume 22, Issue 1, Page(s) 2067

    Abstract: Background: South African universities face a challenge of low throughput rates, with most students failing to complete their studies within the minimum regulatory time. Literature has begun to investigate the contribution of well-being, including ... ...

    Abstract Background: South African universities face a challenge of low throughput rates, with most students failing to complete their studies within the minimum regulatory time. Literature has begun to investigate the contribution of well-being, including mental health, with depression among students being one of the most common mental disorders explored. However, locally relevant research exploring associations between depression and academic performance has been limited. This research hypothesizes that the presence of depression symptoms, when controlling for key socio-demographic factors, has an adverse impact on student academic outcomes and contributes to the delay in the academic progression of students.
    Methods: The study used a cross-sectional design. Data were collected in 2019 from first-time, first-year undergraduate students using a self-administered online questionnaire. In total, 1,642 students completed the survey. The Patient Health Questionnaire-9 (PHQ-9) was used to screen for depression symptoms. Data on students' academic performance were obtained from institutional records. Bivariate and multivariate regression analyses were used to examine associations between depression symptoms and academic performance.
    Results: Most participants (76%) successfully progressed (meeting the requirements to proceed to the second year of university study). Of the participants, 10% displayed symptoms of severe depression. The likelihood of progression delay (not meeting the academic requirements to proceed to the second year of university study) increased with the severity of depression symptoms. Moderate depression symptoms nearly doubled the adjusted odds of progression delay (aOR = 1.98, 95% CI: 1.30-3.00, p = 0.001). The likelihood of progression delay was nearly tripled by moderate severe depression symptoms (aOR = 2.70, 95% CI:1.70-4.36, p < 0.001) and severe depression symptoms (aOR = 2.59, 95% CI:1.54-4.36, p < 0.001). The model controlled for field of study, financial aid support as well as sex and race.
    Conclusion: Higher levels of depression symptoms among first-year university students are associated with a greater likelihood of progression delay and may contribute to the low throughput rates currently seen in South African universities. It is important for students, universities and government departments to recognize student mental wellness needs and how these can be met.
    MeSH term(s) Humans ; Universities ; Cross-Sectional Studies ; Depression/epidemiology ; Depression/psychology ; South Africa/epidemiology ; Students/psychology ; Academic Performance ; Surveys and Questionnaires
    Language English
    Publishing date 2022-11-11
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2041338-5
    ISSN 1471-2458 ; 1471-2458
    ISSN (online) 1471-2458
    ISSN 1471-2458
    DOI 10.1186/s12889-022-14517-7
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article: Factors affecting species richness of tree regeneration in mixed-wood stands of central Maine

    Olson, M.G / Wagner, R.G

    Journal of vegetation science. 2011 Apr., v. 22, no. 2

    2011  

    Abstract: Question: Two questions about within-stand spatial variability are addressed in this paper. How does species richness of tree regeneration respond to small-scale ecological gradients, and what effect does natural Abies balsamea abundance have on the ... ...

    Abstract Question: Two questions about within-stand spatial variability are addressed in this paper. How does species richness of tree regeneration respond to small-scale ecological gradients, and what effect does natural Abies balsamea abundance have on the species richness of other tree regeneration? Location: A long-term, gap-silviculture experiment, Acadian mixed-wood forest, Maine, USA. Methods: Eight stands treated with and without gap harvesting were sampled to capture sub-stand heterogeneity of understorey tree regeneration concurrently with patterning of local stand conditions. Spatial and non-spatial models were developed to test the relationships between two response variables [species richness of small (height ≥0.1 m, but <0.75 m) and large (height ≥0.75 m, but <1.4 m) regeneration] and five explanatory variables (depth to water table, percentage canopy transmittance, A. balsamea regeneration density, and overstorey basal area and species richness). Results: Despite high unexplained variance for all models, consistent associations among variables were found. Negative associations were found between: (1) the species richness of small regeneration and A. balsamea regeneration density and (2) the species richness of large regeneration and overstorey basal area. Positive associations were found between: (1) the species richness of small regeneration and both overstorey basal area and species richness and (2) the species richness of small and large regeneration and canopy transmittance. Conclusions: Promoting tree species diversity in Acadian mixed-wood stands may not be achievable through the use of gap-harvesting alone if the density of understorey Abies balsamea is not reduced either naturally or through silvicultural intervention.
    Keywords Abies balsamea ; basal area ; canopy ; forests ; harvesting ; models ; overstory ; species diversity ; transmittance ; trees ; understory ; variance ; water table ; Maine
    Language English
    Size p. 303-311.
    Publishing place Opulus Press
    Document type Article
    ZDB-ID 1053769-7
    ISSN 1100-9233
    ISSN 1100-9233
    DOI 10.1111/j.1654-1103.2011.01258.x
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Do helminths cause epilepsy?

    Wagner, R G / Newton, C R

    Parasite immunology

    2004  Volume 31, Issue 11, Page(s) 697–705

    Abstract: Both helminthiases and epilepsy occur globally, and are particularly prevalent in developing regions of the world. Studies have suggested an association between epilepsy and helminth infection, but a causal relationship is not established in many ... ...

    Abstract Both helminthiases and epilepsy occur globally, and are particularly prevalent in developing regions of the world. Studies have suggested an association between epilepsy and helminth infection, but a causal relationship is not established in many helminths, except perhaps with neurocysticercosis. We review the available literature on the global burden of helminths, and the epidemiological evidence linking helminths to epilepsy. We discuss possible routes that helminths affect the central nervous system (CNS) of humans and the immunological response to helminth infection in the CNS, looking at possible mechanisms of epileptogenesis. Finally, we discuss the current gaps in knowledge about the interaction between helminths and epilepsy.
    MeSH term(s) Animals ; Central Nervous System/parasitology ; Epilepsy/epidemiology ; Epilepsy/etiology ; Helminthiasis/complications ; Helminthiasis/epidemiology ; Helminthiasis/immunology ; Helminths/pathogenicity ; Host-Parasite Interactions ; Humans ; Virulence
    Language English
    Publishing date 2004-07-08
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 424444-8
    ISSN 1365-3024 ; 0141-9838
    ISSN (online) 1365-3024
    ISSN 0141-9838
    DOI 10.1111/j.1365-3024.2009.01128.x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Do helminths cause epilepsy

    WAGNER, R.G / NEWTON, C.R

    Parasite immunology. 2009 Nov., v. 31, no. 11

    2009  

    Abstract: Both helminthiases and epilepsy occur globally, and are particularly prevalent in developing regions of the world. Studies have suggested an association between epilepsy and helminth infection, but a causal relationship is not established in many ... ...

    Abstract Both helminthiases and epilepsy occur globally, and are particularly prevalent in developing regions of the world. Studies have suggested an association between epilepsy and helminth infection, but a causal relationship is not established in many helminths, except perhaps with neurocysticercosis. We review the available literature on the global burden of helminths, and the epidemiological evidence linking helminths to epilepsy. We discuss possible routes that helminths affect the central nervous system (CNS) of humans and the immunological response to helminth infection in the CNS, looking at possible mechanisms of epileptogenesis. Finally, we discuss the current gaps in knowledge about the interaction between helminths and epilepsy.
    Keywords epilepsy ; helminths ; pathogenesis ; seizures
    Language English
    Dates of publication 2009-11
    Size p. 697-705.
    Publisher Blackwell Publishing Ltd
    Publishing place Oxford, UK
    Document type Article
    ZDB-ID 424444-8
    ISSN 1365-3024 ; 0141-9838
    ISSN (online) 1365-3024
    ISSN 0141-9838
    DOI 10.1111/j.1365-3024.2009.01128.x
    Database NAL-Catalogue (AGRICOLA)

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  5. Article: Influence of management intensity on the productivity of early successional Acadian stands in eastern Maine

    Nelson, A.S / Wagner, R.G / Saunders, M.R / Weiskittel, A.R

    Forestry. 2013 Jan., v. 86, no. 1

    2013  

    Abstract: Early successional stands composed of naturally regenerated hardwood and conifer species are abundant in the forests of northeastern North America. Substantial improvements in the composition and growth of these stands may be possible with early ... ...

    Abstract Early successional stands composed of naturally regenerated hardwood and conifer species are abundant in the forests of northeastern North America. Substantial improvements in the composition and growth of these stands may be possible with early management intervention. Unfortunately, stand responses to early management inputs are poorly understood since many of these stands are rarely manipulated. We examined the response of early successional stands to combinations of two management intensities (with and without enrichment planting and different levels of vegetation control) and three compositional objectives (hardwood, mixedwood and conifer). The treatments were designed to represent management options available in the region, including hardwood thinning, conifer release and a combination of treatments to promote hardwood–conifer mixedwood stands. Seven years after treatment, yields of the two hardwood thinning treatments ranged from 43.4 to 56.6 Mg ha−1, which were similar to the 52.9 Mg ha−1 yield of the untreated control but with 17 and 46% lower densities, respectively. In the conifer release treatments, the removal of hardwoods promoted conifer dominance and resulted in yields between 19.9 and 30.4 Mg ha−1 7 years after treatment. The conifer release treatments will likely be dominated by conifers in the future with varying hardwood densities due to hardwoods establishing in gaps without conifers. After 7 years, yields of the mixedwood treatments were between 19 and 47% greater than the conifer release treatments due to the retention of thinned hardwood stems and represent stands that dominate much of the forestland in the region. Results from this study demonstrated that early successional stands can be effectively managed during early stand development to improve growth and the longer term composition.
    Keywords conifers ; forests ; hardwood ; planting ; stems ; Maine
    Language English
    Dates of publication 2013-01
    Size p. 79-90.
    Publishing place Oxford University Press
    Document type Article
    ZDB-ID 212942-5
    ISSN 0015-752X
    ISSN 0015-752X
    DOI 10.1093/forestry/cps064
    Database NAL-Catalogue (AGRICOLA)

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  6. Article ; Online: Gut microbiome profiling of a rural and urban South African cohort reveals biomarkers of a population in lifestyle transition.

    Oduaran, O H / Tamburini, F B / Sahibdeen, V / Brewster, R / Gómez-Olivé, F X / Kahn, K / Norris, S A / Tollman, S M / Twine, R / Wade, A N / Wagner, R G / Lombard, Z / Bhatt, A S / Hazelhurst, S

    BMC microbiology

    2020  Volume 20, Issue 1, Page(s) 330

    Abstract: Background: Comparisons of traditional hunter-gatherers and pre-agricultural communities in Africa with urban and suburban Western North American and European cohorts have clearly shown that diet, lifestyle and environment are associated with gut ... ...

    Abstract Background: Comparisons of traditional hunter-gatherers and pre-agricultural communities in Africa with urban and suburban Western North American and European cohorts have clearly shown that diet, lifestyle and environment are associated with gut microbiome composition. Yet, little is known about the gut microbiome composition of most communities in the very diverse African continent. South Africa comprises a richly diverse ethnolinguistic population that is experiencing an ongoing epidemiological transition and concurrent spike in the prevalence of obesity, largely attributed to a shift towards more Westernized diets and increasingly inactive lifestyle practices. To characterize the microbiome of African adults living in more mainstream lifestyle settings and investigate associations between the microbiome and obesity, we conducted a pilot study, designed collaboratively with community leaders, in two South African cohorts representative of urban and transitioning rural populations. As the rate of overweight and obesity is particularly high in women, we collected single time-point stool samples from 170 HIV-negative women (51 at Soweto; 119 at Bushbuckridge), performed 16S rRNA gene sequencing on these samples and compared the data to concurrently collected anthropometric data.
    Results: We found the overall gut microbiome of our cohorts to be reflective of their ongoing epidemiological transition. Specifically, we find that geographical location was more important for sample clustering than lean/obese status and observed a relatively higher abundance of the Melainabacteria, Vampirovibrio, a predatory bacterium, in Bushbuckridge. Also, Prevotella, despite its generally high prevalence in the cohorts, showed an association with obesity. In comparisons with benchmarked datasets representative of non-Western populations, relatively higher abundance values were observed in our dataset for Barnesiella (log
    Conclusions: Altogether, this work identifies putative microbial features associated with host health in a historically understudied community undergoing an epidemiological transition. Furthermore, we note the crucial role of community engagement to the success of a study in an African setting, the importance of more population-specific studies to inform targeted interventions as well as present a basic foundation for future research.
    MeSH term(s) Adult ; Aged ; Bacteria/genetics ; Biomarkers ; Cohort Studies ; Diet ; Feces/microbiology ; Female ; Gastrointestinal Microbiome/genetics ; Humans ; Life Style/ethnology ; Microbiota/genetics ; Middle Aged ; Obesity/microbiology ; Pilot Projects ; RNA, Ribosomal, 16S/genetics ; Rural Population ; South Africa/ethnology
    Chemical Substances Biomarkers ; RNA, Ribosomal, 16S
    Language English
    Publishing date 2020-10-31
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2041505-9
    ISSN 1471-2180 ; 1471-2180
    ISSN (online) 1471-2180
    ISSN 1471-2180
    DOI 10.1186/s12866-020-02017-w
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Competition and critical-period thresholds for vegetation management in young conifer stands

    Wagner, R.G

    Forest Vegetation Management Conference. Proceedings ... annual Forest Vegetation Management Conference. 2000. (21st)

    2000  

    Keywords plant competition ; forests
    Language English
    Size p. 78-86.
    Document type Article
    Note Meeting held January 18-20, 2000, Redding, California.
    ISSN 1057-2147
    Database NAL-Catalogue (AGRICOLA)

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  8. Article: Competition and critical-period thresholds for vegetation management decisions in young conifer stands

    Wagner, R.G

    Forestry chronicle. Nov/Dec 2000. v. 76 (6)

    2000  

    Abstract: Thresholds define the time when management action is required to prevent a loss in yield, but have remained relatively elusive in forest vegetation management. Hundreds of studies quantifying the effects of competing vegetation in young forest stands, ... ...

    Abstract Thresholds define the time when management action is required to prevent a loss in yield, but have remained relatively elusive in forest vegetation management. Hundreds of studies quantifying the effects of competing vegetation in young forest stands, however, have produced reasonably consistent patterns and magnitudes of tree responses. These consistencies reveal a set of general guidelines that can be used to assist forest managers in deciding when vegetation management treatments are needed. Among the variety of vegetation management thresholds that have been defined, competition and critical-period thresholds can be interpreted from existing forest vegetation research. Competition thresholds define the vegetation density at which yield loss begins to occur and varies depending on whether the manager's objective is to maximize survival, height increment, basal area growth, or biomass. These interactions also appear to vary depending on whether woody or herbaceous plants are the principal competitors. The critical-period threshold defines the time period when vegetation control must occur to prevent yield loss. Results from one critical-period study indicate that capturing the potential for conifer growth requires control of vegetation for the first several years after planting.
    Keywords forests ; plant competition ; duration ; yields ; understory ; plant density ; mortality ; height ; basal area ; biomass production ; intensive forestry
    Language English
    Dates of publication 2000-11
    Size p. 961-968.
    Document type Article
    Note Summary in French.
    ZDB-ID 348848-2
    ISSN 0015-7546
    ISSN 0015-7546
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  9. Article: Long-term spatial and structural dynamics in Acadian mixedwood stands managed under various silvicultural systems

    Saunders, M.R / Wagner, R.G

    Canadian journal of forest research. 2008 Mar., v. 38, no. 3

    2008  

    Abstract: Using inventory data from a long-term silviculture experiment in east-central Maine, spatial models were developed to analyze 28 years (1974-2002) of stand structural dynamics. Differences in spatial pattern, species mingling, height differentiation, and ...

    Abstract Using inventory data from a long-term silviculture experiment in east-central Maine, spatial models were developed to analyze 28 years (1974-2002) of stand structural dynamics. Differences in spatial pattern, species mingling, height differentiation, and relative stand complexity index (rSCI) were compared among five treatments: commercial clear-cutting, fixed diameter-limit, 5 year single-tree selection, three-stage shelterwood (both with and without precommercial thinning), and unharvested natural areas. Regardless of treatment, regeneration events (whether induced by natural breakup of the overstory or by harvesting) increased aggregation in spatial pattern and reduced species mingling, more so in the commercial clearcut and fixed diameter-limit treatments where hardwood densities were highest. Regular spatial patterns were rare. Height differentiation values for individual trees and stand-level mean rSCI were generally highest in untreated natural areas and 5 year selection treatments, intermediate in commercial clearcut and fixed diameter-limit treatments, and lowest in three-stage shelterwood treatments. After a brief adjustment period, precommercial thinning in a shelterwood treated stand generally increased species mingling, height differentiation, and rSCI. Two untreated natural areas exhibited divergent pathways of structural development. Dynamics in uneven-aged selection treatments more closely resembled that of the untreated natural areas than did the shelterwood, commercial clearcut, or fixed diameter-limit treatments.
    Keywords forest stands ; stand structure ; forest trees ; spatial distribution ; silvicultural systems ; silvicultural practices ; forest regeneration ; height ; clearcutting ; shelterwood systems ; species diversity ; long term experiments ; uneven-aged stands ; models ; equations ; Maine
    Language English
    Dates of publication 2008-03
    Size p. 498-517.
    Document type Article
    Note Summary in French.
    ZDB-ID 430062-2
    ISSN 0045-5067
    ISSN 0045-5067
    DOI 10.1139/X07-155
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  10. Article: Early stand production of hybrid poplar and white spruce in mixed and monospecific plantations in eastern Maine

    Nelson, A. S / Saunders, M. R / Wagner, R. G / Weiskittel, A. R

    New forests. 2012 July, v. 43, no. 4

    2012  

    Abstract: Forest plantations in the northeastern United States comprise a small proportion of the total forest area. Most plantations are typically softwood dominated and managed for sawlog and pulpwood production, while high-yield hardwood plantations for ... ...

    Abstract Forest plantations in the northeastern United States comprise a small proportion of the total forest area. Most plantations are typically softwood dominated and managed for sawlog and pulpwood production, while high-yield hardwood plantations for bioenergy feedstocks have not been as widely investigated. The objective of this study was to compare the biomass production of planted white spruce (Picea glauca (Moench) Voss) and hybrid poplar (Populus spp.) plantations (four clones) in monoculture, and in mixture of the two on a typical reforestation site in Maine. Three years following planting, hybrid poplar height and ground line diameter growth rates began to diverge among clones, and by 6 years, the Populus nigra × Populus maximowiczii (NM6) clone clearly outperformed three Populus deltoides × Populus nigra clones (D51, DN10 and DN70) both in pure stands and in mixtures with white spruce. In mixture, we found the yield of white spruce to decline as the yield of hybrid poplar increased. Overall, yields of white spruce monocultures were comparable to those reported in eastern Canada, while the hybrid poplar biomass yields were substantially lower than those reported from studies on abandoned agricultural lands, likely due to the harsher soil conditions at our site. The dominance of rocky and poorly drained sites (like the one tested in this study) across Maine will likely limit the feasibility of widespread hybrid poplar plantations, and thus constrains their potential use as a bioenergy feedstock.
    Keywords Picea glauca ; Populus alba ; Populus deltoides ; Populus maximowiczii ; Populus nigra ; biomass production ; clones ; feedstocks ; forest plantations ; forests ; hardwood ; hybrids ; pulpwood ; pure stands ; reforestation ; softwood ; Canada ; Maine
    Language English
    Dates of publication 2012-07
    Size p. 519-534.
    Publishing place Springer-Verlag
    Document type Article
    ZDB-ID 1038718-3
    ISSN 0169-4286
    ISSN 0169-4286
    DOI 10.1007/s11056-011-9296-2
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