204 research outputs found
Population dynamics of epiphytic orchids in a metapopulation context
Background and Aims Populations of many epiphytes show a patchy distribution where clusters of plants growing on individual trees are spatially separated and may thus function as metapopulations. Seed dispersal is necessary to (re)colonize unoccupied habitats, and to transfer seeds from high- to low-competition patches. Increasing dispersal distances, however, reduces local fecundity and the probability that seeds will find a safe site outside the original patch. Thus, there is a conflict between seed survival and colonization.
Methods Populations of three epiphytic orchids were monitored over three years in a Mexican humid montane forest and analysed with spatially averaged and with spatially explicit matrix metapopulation models. In the latter, population dynamics at the scale of the subpopulations (epiphytes on individual host trees) are based on detailed stage-structured observations of transition probabilities and trees are connected by a dispersal function.
Key Results Population growth rates differed among trees and years. While ignoring these differences, and averaging the population matrices over trees, yields negative population growth, metapopulation models predict stable or growing populations because the trees that support growing subpopulations determine the growth of the metapopulation. Stochastic models which account for the differences among years differed only marginally from deterministic models. Population growth rates were significantly lower, and extinctions of local patches more frequent in models where higher dispersal results in reduced local fecundity compared with hypothetical models where this is not the case. The difference between the two models increased with increasing mean dispersal distance. Though recolonization events increased with dispersal distance, this could not compensate the losses due to reduced local fecundity.
Conclusions For epiphytes, metapopulation models are useful to capture processes beyond the level of the single host tree, but local processes are equally important to understand epiphyte population dynamics
Epidemiology and surveillance of human (neuro)cysticercosis in Europe: is enhanced surveillance required?
objectives To report on relevant national surveillance systems of (N)CC and taeniasis (the infection
with the adult tapeworm) in the European Union/European Economic Area and to assess the
magnitude of (N)CC occurrence by retrieving information on cases for the period 2000–2016.
methods (N)CC cases were retrieved via national reporting systems, a systematic literature search,
contact with clinicians and a search for relevant ‘International Statistical Classification of Diseases
and Related Health Problems’ (ICD)-based data.
results Mandatory notification systems for (N)CC were found in Hungary, Iceland and Poland.
Ten cases were reported in Poland and none in Hungary and Iceland. Through the systematic
literature review and information given by clinicians, 263 individual and 721 aggregated (N)CC cases
from 19 European countries were identified. ICD-based data were obtained from five countries. From
2000 to 2016, a total of 3489 cases (N)CC cases were coded: 832 in Italy, eight in Latvia, 357 in
Portugal, 2116 in Spain and 176 in Sweden.
conclusion Despite being classified as a possible eradicable disease, (N)CC is still diagnosed across
Europe, yet its true extent and impact remain unclear.Cost, Cystine
Changes in plant diversity in a water‑limited and isolated high‑mountain range (Sierra Nevada, Spain)
Open Access funding provided by University of Natural Resources and Life Sciences Vienna (BOKU). This study was funded by the Austrian Academy of Sciences (project MEDIALPS-Disentangling anthropogenic drivers of climate change impacts on alpine plant species: Alps vs. Mediterranean mountains).Supplementary Information The online version contains supplementary
material available at https ://doi.org/10.1007/s0003 5-021-00246 -x.We thank Manfred Bardy-Durchhalter for managing
the database, Imran Nadeem for discussing climate data preparation,
and National Park and Andalusian Environmental Agency staff
for their assistance in the field in 2015 and 2019, and answering our
questions.Climate change impacts are of a particular concern in small mountain ranges, where cold-adapted plant species have their optimum zone in the upper bioclimatic belts. This is commonly the case in Mediterranean mountains, which often harbour high numbers of endemic species, enhancing the risk of biodiversity losses. This study deals with shifts in vascular plant diversity in the upper zones of the Sierra Nevada, Spain, in relation with climatic parameters during the past two decades. We used vegetation data from permanent plots of three surveys of two GLORIA study regions, spanning a period of 18 years (2001–2019); ERA5 temperature and precipitation data; and snow cover durations, derived from on-site soil temperature data. Relationships between diversity patterns and climate factors were analysed using GLMMs. Species richness showed a decline between 2001 and 2008, and increased thereafter. Species cover increased slightly but significantly, although not for endemic species. While endemics underwent cover losses proportional to non-endemics, more widespread shrub species increased. Precipitation tended to increase during the last decade, after a downward trend since 1960. Precipitation was positively related to species richness, colonisation events, and cover, and negatively to disappearance events. Longer snow cover duration and rising temperatures were also related to increasing species numbers, but not to cover changes. The rapid biotic responses of Mediterranean alpine plants indicate a tight synchronisation with climate fluctuations, especially with water availability. Thus, it rather confirms concerns about biodiversity losses, if projections of increasing temperature in combination with decreasing precipitation hold true.University of Natural Resources and Life Sciences Vienna (BOKU) - Austrian Academy of Science
Patterns of healthcare seeking among people reporting chronic conditions in rural sub-Saharan Africa: findings from a population-based study in Burkina Faso.
OBJECTIVE: Non-communicable diseases are rapidly becoming one of the leading causes of morbidity and mortality in sub-Saharan Africa. Yet, little is known about patterns of healthcare seeking among people with chronic conditions in these settings. We aimed to explore determinants of healthcare seeking among people who reported at least one chronic condition in rural Burkina Faso. METHODS: Data were drawn from a cross-sectional population-based survey conducted across 24 districts on 52 562 individuals from March to June 2017. We used multinomial logistic regression to assess factors associated with seeking care at a formal provider (facility-based care) or at an informal provider (home and traditional treatment) compared to no care. RESULTS: 1124 individuals (2% of all respondents) reported at least one chronic condition. Among those, 22.8% reported formal care use, 10.6% informal care use, and 66.6% no care. The presence of other household members reporting a chronic condition (RRR = 0.57, 95%-CI [0.39, 0.82]) was negatively associated with seeking formal care. Wealthier households (RRR = 2.14, 95%-CI [1.26, 3.64]), perceived illness severity (RRR = 3.23, 95%-CI [2.22, 4.70]) and suffering from major chronic conditions (RRR = 1.54, 95%-CI [1.13, 2.11]) were positively associated with seeking formal care. CONCLUSION: Only a minority of individuals with chronic conditions sought formal care, with important differences due to socio-economic status. Policies and interventions aimed at increasing the availability and affordability of services for early detection and management in peripheral settings should be prioritised
Osteoidosis leads to altered differentiation and function of osteoclasts
In patients with osteomalacia, a defect in bone mineralization leads to changed characteristics of the bone surface. Considering that the properties of the surrounding matrix influence function and differentiation of cells, we aimed to investigate the effect of osteoidosis on differentiation and function of osteoclasts. Based on osteomalacic bone biopsies, a model for osteoidosis in vitro (OIV) was established. Peripheral blood mononuclear cells were differentiated to osteoclasts on mineralized surfaces (MS) as internal control and on OIV. We observed a significantly reduced number of osteoclasts and surface resorption on OIV. Atomic force microscopy revealed a significant effect of the altered degree of mineralization on surface mechanics and an unmasking of collagen fibres on the surface. Indeed, coating of MS with RGD peptides mimicked the resorption phenotype observed in OIV, suggesting that the altered differentiation of osteoclasts on OIV might be associated with an interaction of the cells with amino acid sequences of unmasked extracellular matrix proteins containing RGD sequences. Transcriptome analysis uncovered a strong significant up-regulation of transmembrane glycoprotein TROP2 in osteoclastic cultures on OIV. TROP2 expression on OIV was also confirmed on the protein level and found on the bone surface of patients with osteomalacia. Taken together, our results show a direct influence of the mineralization state of the extracellular matrix surface on differentiation and function of osteoclasts on this surface which may be important for the pathophysiology of osteomalacia and other bone disorders with changed ratio of osteoid to bone
Clinical characteristics and management of neurocysticercosis patients: a retrospective assessment of case reports from Europe
Objectives: Neurocysticercosis (NCC) is a parasitic disease caused by the larval stage of the tapeworm Taenia solium. NCC mainly occurs in Africa, Latin America and South-East Asia and can cause a variety of clinical signs/symptoms. Although it is a rare disease in Europe, it should nonetheless be considered as a differential diagnosis. The aim of this study was to describe clinical characteristics and management of patients with NCC diagnosed and treated in Europe.
Methods: We conducted a systematic search of published and unpublished data on patients diagnosed with NCC in Europe (2000-2019) and extracted demographic, clinical and radiological information on each case, if available.
Results: Out of 293 identified NCC cases, 59% of patients presented initially with epileptic seizures (21% focal onset); 52% presented with headache and 54% had other neurological signs/symptoms. The majority of patients had a travel or migration history (76%), mostly from/to Latin America (38%), Africa (32%) or Asia (30%). Treatment varied largely depending on cyst location and number. The outcome was favorable in 90% of the cases.
Conclusions: Management of NCC in Europe varied considerably but often had a good outcome. Travel and migration to and from areas endemic for Theridion solium will likely result in continued low prevalence of NCC in Europe. Therefore, training and guidance of clinicians is recommended for optimal patient management
A novel approach to fractional calculus: utilizing fractional integrals and derivatives of the Dirac delta function
While the definition of a fractional integral may be codified by Riemann and
Liouville, an agreed-upon fractional derivative has eluded discovery for many
years. This is likely a result of integral definitions including numerous
constants of integration in their results. An elimination of constants of
integration opens the door to an operator that reconciles all known fractional
derivatives and shows surprising results in areas unobserved before, including
the appearance of the Riemann Zeta Function and fractional Laplace and Fourier
Transforms. A new class of functions, known as Zero Functions and closely
related to the Dirac Delta Function, are necessary for one to perform
elementary operations of functions without using constants. The operator also
allows for a generalization of the Volterra integral equation, and provides a
method of solving for Riemann's "complimentary" function introduced during his
research on fractional derivatives
Epidemiology and surveillance of human (neuro)cysticercosis in Europe: is enhanced surveillance required?
Objectives
To report on relevant national surveillance systems of (N)CC and taeniasis (the infection with the adult tapeworm) in the European Union/European Economic Area and to assess the magnitude of (N)CC occurrence by retrieving information on cases for the period 2000–2016.
Methods
(N)CC cases were retrieved via national reporting systems, a systematic literature search, contact with clinicians and a search for relevant ‘International Statistical Classification of Diseases and Related Health Problems’ (ICD)‐based data.
Results
Mandatory notification systems for (N)CC were found in Hungary, Iceland and Poland. Ten cases were reported in Poland and none in Hungary and Iceland. Through the systematic literature review and information given by clinicians, 263 individual and 721 aggregated (N)CC cases from 19 European countries were identified. ICD‐based data were obtained from five countries. From 2000 to 2016, a total of 3489 cases (N)CC cases were coded: 832 in Italy, eight in Latvia, 357 in Portugal, 2116 in Spain and 176 in Sweden.
Conclusion
Despite being classified as a possible eradicable disease, (N)CC is still diagnosed across Europe, yet its true extent and impact remain unclear.info:eu-repo/semantics/publishedVersio
is enhanced surveillance required?
OBJECTIVES: To report on relevant national surveillance systems of (N)CC and taeniasis (the infection with the adult tapeworm) in the European Union/European Economic Area, and to assess the magnitude of (N)CC occurrence by retrieving information on cases for the period 2000-2016. METHODS: (N)CC cases were retrieved via national reporting systems, a systematic literature search, contact with clinicians, and a search for relevant "International Statistical Classification of Diseases and Related Health Problems" (ICD)-based data. RESULTS: Mandatory notification systems for (N)CC were found in Hungary, Iceland and Poland. Ten cases were reported in Poland and none in Hungary and Iceland. Through the systematic literature review and information given by clinicians, 263 individual and 721 aggregated (N)CC cases from 19 European countries were identified. ICD-based data were obtained from five countries. From 2000 to 2016, a total of 3,489 cases (N)CC cases were coded: 832 in Italy, 8 in Latvia, 357 in Portugal, 2116 in Spain and 176 in Sweden. CONCLUSION: Despite being classified as a possible eradicable disease, (N)CC is still diagnosed across Europe, yet its true extent and impact remain unclear.publishersversionpublishe
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