517 research outputs found
Monitoring and modeling the invasion of the fast spreading alien Senecio inaequidens DC. in an alpine region
We modeled the distribution of the South African alien Senecio inaequidens DC. in the Aosta Valley, Western Italian Alps, using data extracted from the Regional floristic database and from an intensive field survey carried out in years 2009-2010. The aims of the work were (1) to evaluate whether the species is in the introduction, colonization, or establishment stage of invasion, (2) to detect the environmental factors that drive the invasion process, and (3) to highlight the potential range of distribution of the alien species. The modeling framework was a stepwise generalized linear model (GLM), using gridded presence/absence data and environmental predictors such as topography, climate, land use, and anthropogenic and natural disturbances. GLM were fit both with and without an additional independent variable to take into account current dispersal limitations. S. inaequidens displayed a very fast spread in the Aosta Valley in the years 1990-2010. The species was positively associated with roads and rivers, southern slopes, and negatively with elevation. However, it was found at an elevation of 1600 m, showing the ability to reach higher elevations than those observed for other invasive alien species, and confirming to be pre-adapted to mountain conditions. The difference between the species distribution models, with and without dispersal constraints, suggested that the availability of seed sources still limits the potential distribution of the species, rather than the environmental variables, and that the realized regional niche differs to a great extent from the equilibrium niche. When limitations to the seed source cease (i.e., in the establishment stage), the species will likely invade large areas that are currently characterized by pastures and grasslands with native species of high agricultural importance. The invasion of S. inaequidens should therefore be considered a serious threat, due to its potential to invade mountain regions, and in particular to colonize habitats used for grazing and forage, thus leading to a high risk for cattle and human health. We discuss the relevance of the results both concerning communication with the public and to support local eradication and control activities. The inclusion of S. inaequidens in the "black list" of the regional law for the conservation of alpine flora (L.R. 45/2009) will help to transfer the information and support invasion control, in particular at medium elevations
On doing relevant and rigorous experiments: Review and recommendations
Although experiments are the gold standard for establishing causality, several threats can undermine the internal validity of experimental findings. In this article, we first discuss these threats, which include the lack of consequential decisions and outcomes, deception, demand effects and unfair comparisons, as well as issues concerning statistical validity (e.g., minimum sample size per cell, estimating variance correctly). We expose each problem, show potential solutions, and bring to the fore issues of relevance of the findings (i.e., external and ecological validity). Thereafter, we take stock of the state-of-the-science regarding validity threats using a representative sample of 468 recent experiments from 258 articles published in top-tier journals. We compare research practices in three fields of study—management, social psychology, and economics, which regularly use experimental research—to operations management, which has recently begun to use the experimental paradigm. Our results underscore the importance for journals and authors to follow what we identify to be best-practice methodological suggestions (i.e., the “ten commandments” of experimental research). We show that—on average—markers of methodological rigor and generalizability positively and significantly predict the citations received by published articles. Finally, given that experiments are infeasible in some settings, we conclude with a brief review of often overlooked quasi-experimental designs, which are useful for generating strong counterfactuals and hence allow making causal claims in the field
Metabolic syndrome, left ventricular hypertrophy and carotid atherosclerosis in hypertension: a gender-based study.
Background. The influence of gender on the association between metabolic syndrome (MS) and subclinical organ damage (OD) has been poorly investigated. The aim of this study was to investigate whether the risk of developing left ventricular hypertrophy (LVH) and carotid atherosclerosis is different in men and women with MS. Methods. A total of 3752 untreated and treated hypertensive patients (mean age 53.3 ± 12.6, 52.7% men) were considered for this analysis. All patients underwent standard ultrasonographic investigations searching for LVH and carotid atherosclerosis. The MS was defined according to ATP III criteria. Results. LVH was more prevalent in women and men with the MS compared with their counterparts (58% vs 34% and 48% vs 33%, respectively, p < 0.001). This was also the case for carotid plaque prevalence (61% vs 42% and 57% vs 44%, p < 0.001). The prevalence of OD was not different between men and women with MS, after adjusting for confounders. In multivariate analysis, abdominal obesity was the most important MS component independently related to LVH in both genders, followed by blood pressure. As for carotid plaques, blood pressure, hyperglycemia and hypertriglyceridemia turned out to be independent correlates regardless of gender. Conclusions. Our data indicate that MS is associated with a higher risk of LVH and carotid atherosclerosis irrespective of gender; these findings do not support a gender influence in the association between MS and subclinical OD. © 2013 Scandinavian Foundation for Cardiovascular Research
Temporal variations in leaf traits, chemical composition and in vitro true digestibility of four temperate fodder tree species.
Laparoscopic versus Open Surgery in Complicated Appendicitis in Children Less Than 5 Years Old: A Six-Year Single-Centre Experience
Introduction. Acute appendicitis is the most common surgical emergency in the pediatric population. The peak incidence occurs in the first decade of life, while it is uncommon to face appendicitis in children younger than 5 years of age. Laparoscopy is now demonstrated to be the optimal approach also to treat complicated appendicitis, but in very young children this standardized operation is not always easy to perform. Material and Methods. From January 2009 to December 2015 we operated on 525 acute appendicitis, with 120 patients less than 5 years of age. Results. 90 children had a complicated appendicitis (localized or diffuse peritonitis): 43 (48%) were operated on by open approach and 47 (52%) by laparoscopy. The overall incidence of postoperative complications was greater in the open appendectomy group (63% versus 26%) and all severe complications requiring reintervention (6% of cases: 3 postoperative abscesses resolved with ultrasound guided percutaneous abscess drainage; 1 tubal surgery for salpingitis; 1 adhesion-related ileus requiring relaparotomy) were mostly associated with open surgery. Conclusions. Laparoscopic surgery resulted as the best approach for treating complicated appendicitis also in younger children, with minor and less severe postoperative complications compared to open surgery
Correlation between the progression of optic disc and visual field changes in glaucoma
Visual field test and optic disc evaluation are the standard examination techniques used to detect the onset and progression of glaucoma. This explorative study was performed to assess the temporal correlation between visual field and optic disc changes in eyes with ocular hypertension and well-established glaucoma. Eighty-six hypertensive and 16 glaucomatous eyes were followed up for a period of up to 9 years (average 4.4 yrs) using kinetic and computerized static perimetry and optic disc manual morphometry. Perimetric changes were based on a series of strict criteria and optic disc changes were based as a reduction in the baseline rim area/disc area ratio (R/D) measurement exceeding the 99% confidence interval for intraobserver reproducibility (7.7%). Optic disc changes were found prior to visual field changes in four hypertensive eyes, whereas visual field changes were found prior to disc changes in six glaucomatous eyes (p = 0.042). The results of our explorative study suggest that quantitative optic disc analysis may be more sensitive than visual field examination in detecting early glaucomatous changes, whereas visual field examination may be more sensitive than quantitative optic disc analysis in detecting glaucomatous progressions in eyes with well established glaucoma
Defective dystrophic thymus determines degenerative changes in skeletal muscle.
In Duchenne muscular dystrophy (DMD), sarcolemma fragility and myofiber necrosis produce cellular debris that attract inflammatory cells. Macrophages and T-lymphocytes infiltrate muscles in response to damage-associated molecular pattern signalling and the release of TNF-α, TGF-β and interleukins prevent skeletal muscle improvement from the inflammation. This immunological scenario was extended by the discovery of a specific response to muscle antigens and a role for regulatory T cells (Tregs) in muscle regeneration. Normally, autoimmunity is avoided by autoreactive T-lymphocyte deletion within thymus, while in the periphery Tregs monitor effector T-cells escaping from central regulatory control. Here, we report impairment of thymus architecture of mdx mice together with decreased expression of ghrelin, autophagy dysfunction and AIRE down-regulation. Transplantation of dystrophic thymus in recipient nude mice determine the up-regulation of inflammatory/fibrotic markers, marked metabolic breakdown that leads to muscle atrophy and loss of force. These results indicate that involution of dystrophic thymus exacerbates muscular dystrophy by altering central immune tolerance
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