Analysis of variance (ANOVA) is a usual way for analysing experiments. However, depending on the design and/or the analysis scheme, it can be a hard task. ExpDes, acronym for Experimental Designs, is ...a package that intends to turn such task easier. Devoted to fixed models and balanced experiments (no missing data), ExpDes allows user to deal with additional treatments in a single run, several experiment designs and exhibits standard and easy-to-interpret outputs. It was developed at the Exact Sciences Institute of the Federal University of Alfenas, Brazil. Stable versions of package ExpDes are available on CRAN (Comprehensive R Archive Network) since 2012. Based on users' feedback, the package was used to illustrate graduation and post-graduation classes and to carry out data analysis, in Brazil and many other countries. Package ExpDes differs from the other R tools in its easiness in use and cleanliness of output.
1. Biodiversity is an important component of natural ecosystems, with higher species richness often correlating with an increase in ecosystem productivity. Yet, this relationship varies substantially ...across environments, typically becoming less pronounced at high levels of species richness. However, species richness alone cannot reflect all important properties of a community, including community evenness, which may mediate the relationship between biodiversity and productivity. If the evenness of a community correlates negatively with richness across forests globally, then a greater number of species may not always increase overall diversity and productivity of the system. Theoretical work and local empirical studies have shown that the effect of evenness on ecosystem functioning may be especially strong at high richness levels, yet the consistency of this remains untested at a global scale.
2. Here, we used a dataset of forests from across the globe, which includes composition, biomass accumulation and net primary productivity, to explore whether productivity correlates with community evenness and richness in a way that evenness appears to buffer the effect of richness. Specifically, we evaluated whether low levels of evenness in speciose communities correlate with the attenuation of the richness–productivity relationship.
3. We found that tree species richness and evenness are negatively correlated across forests globally, with highly speciose forests typically comprising a few dominant and many rare species. Furthermore, we found that the correlation between diversity and productivity changes with evenness: at low richness, uneven communities are more productive, while at high richness, even communities are more productive.
4. Synthesis. Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions.
Collectively, these results demonstrate that evenness is an integral component of the relationship between biodiversity and productivity, and that the attenuating effect of richness on forest productivity might be partly explained by low evenness in speciose communities. Productivity generally increases with species richness, until reduced evenness limits the overall increases in community diversity. Our research suggests that evenness is a fundamental component of biodiversity–ecosystem function relationships, and is of critical importance for guiding conservation and sustainable ecosystem management decisions.
The present study was conducted to evaluate the relationship between biochemical, virological, and histological response during the course of interferon therapy. Ninety consecutive patients with ...well‐documented chronic hepatitis C virus (HCV) were treated with 5 MU of interferon alfa‐2b three times weekly for 6 months. Liver biopsy was performed, and serum HCV RNA titer was measured before and at the completion of interferon treatment. Normalization of serum alanine transaminase (ALT) concentration (biochemical response) was observed in 50% of patients. In these patients, Knodell score declined significantly from 9.6 ± 0.5 to 5.0 ± 0.5 (P < .01), and 75% became HCV RNA negative. The remaining patients (50%) were biochemical nonresponders; mean Knodell score declined from 9.6 ± 0.5 to 7.7 ± 0.5 (P < .01), and 11% became HCV RNA negative. For both biochemical responders and nonresponders, the decline in Knodell score was confined to the components of hepatic inflammation (piecemeal necrosis + lobular + portal inflammation); no change in fibrosis was observed. Hepatic inflammation declined by 5 points or more in 69% of biochemical responders and 48% of biochemical nonresponders, and by at least 50% from pretreatment values in 74% and 38% of biochemical responders and biochemical nonresponders, respectively. For all patients (both biochemical responders and nonresponders) who remained viremic at the conclusion of interferon therapy, the reduction in hepatic inflammation was a linear function of the decline in HCV RNA titer. We conclude that more than one third of patients who had no biochemical response after 6 months of interferon therapy achieved a similar improvement in hepatic histology as was observed in patients with biochemical response. This improvement in hepatic histology appeared to correlate with a reduction in HCV RNA titer, especially in patients who remained viremic.
Planet transformations caused by human intervention in the last 200 years are largely due to chemical impact. Therefore, this study aimed to identify and analyze the environmental perception of ...undergraduate students and lecturers in the Chemistry course of the Federal University of Lavras, accounting for the topics "Environmental Definition" and "Relationship between Chemistry and Environment". Two thematic axes for discussion were proposed using theories of Social Representation and Environmental Complexity, with the aim of stimulating the conservationist reasoning and actions. Such axes were proposed to give support to the education of chemists at the undergraduate level.
Asian Americans are one of the fastest-growing populations in the United States. A relatively large subset of this population carries a unique loss-of-function point mutation in aldehyde ...dehydrogenase 2 (ALDH2), ALDH2*2. Found in approximately 560 million people of East Asian descent, ALDH2*2 reduces enzymatic activity by approximately 60% to 80% in heterozygotes. Furthermore, this variant is associated with a higher risk for several diseases affecting many organ systems, including a particularly high incidence relative to the general population of esophageal cancer, myocardial infarction, and osteoporosis. In this review, we discuss the pathophysiology associated with the ALDH2*2 variant, describe why this variant needs to be considered when selecting drug treatments, and suggest a personalized medicine approach for Asian American carriers of this variant. We also discuss future clinical and translational perspectives regarding ALDH2*2 research.
Multivariate Image Analysis Applied to Quantitative Structure–Activity Relationships (MIA‐QSAR) has been recently implemented as a method to model and predict biological activities of drug‐like ...compounds. This method is based on the treatment of 2‐D chemical structures, which can be built using specific packages for chemical drawing. These chemical structures correlate with the corresponding bioactivities through descriptors, which are pixels (binaries) of the 2‐D images; the variable moiety of chemical structures (substituent groups) explains the variance in the bioactivities column vector of a series of compounds. Thus, the way in which chemical structures are drawn (font type and size, representation of chemical groups, format in which images are saved) should influence the results of prediction. This work reports the statistics of prediction for a case study, a series of anti‐HIV compounds, and reveals that the results of prediction is independent of the way in which molecules are drawn.
Despite a strong increase in research on seamounts and oceanic islands ecology and biogeography, many basic aspects of their biodiversity are still unknown. In the southwestern Atlantic, the ...Vitória-Trindade Seamount Chain (VTC) extends ca. 1,200 km offshore the Brazilian continental shelf, from the Vitória seamount to the oceanic islands of Trindade and Martin Vaz. For a long time, most of the biological information available regarded its islands. Our study presents and analyzes an extensive database on the VTC fish biodiversity, built on data compiled from literature and recent scientific expeditions that assessed both shallow to mesophotic environments. A total of 273 species were recorded, 211 of which occur on seamounts and 173 at the islands. New records for seamounts or islands include 191 reef fish species and 64 depth range extensions. The structure of fish assemblages was similar between islands and seamounts, not differing in species geographic distribution, trophic composition, or spawning strategies. Main differences were related to endemism, higher at the islands, and to the number of endangered species, higher at the seamounts. Since unregulated fishing activities are common in the region, and mining activities are expected to drastically increase in the near future (carbonates on seamount summits and metals on slopes), this unique biodiversity needs urgent attention and management.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Understanding Alzheimer's disease (AD) heterogeneity is important for understanding the underlying pathophysiological mechanisms of AD. However, AD atrophy subtypes may reflect different disease ...stages or biologically distinct subtypes. Here we use longitudinal magnetic resonance imaging data (891 participants with AD dementia, 305 healthy control participants) from four international cohorts, and longitudinal clustering to estimate differential atrophy trajectories from the age of clinical disease onset. Our findings (in amyloid-β positive AD patients) show five distinct longitudinal patterns of atrophy with different demographical and cognitive characteristics. Some previously reported atrophy subtypes may reflect disease stages rather than distinct subtypes. The heterogeneity in atrophy rates and cognitive decline within the five longitudinal atrophy patterns, potentially expresses a complex combination of protective/risk factors and concomitant non-AD pathologies. By alternating between the cross-sectional and longitudinal understanding of AD subtypes these analyses may allow better understanding of disease heterogeneity.
Different subtypes of Alzheimer's disease (AD) with characteristic distributions of neurofibrillary tangles and corresponding brain atrophy patterns have been identified using structural magnetic ...resonance imaging (MRI). However, the underlying biological mechanisms that determine this differential expression of neurofibrillary tangles are still unknown. Here, we applied graph theoretical analysis to structural MRI data to test the hypothesis that differential network disruption is at the basis of the emergence of these AD subtypes. We studied a total of 175 AD patients and 81 controls. Subtyping was done using the Scheltens' scale for medial temporal lobe atrophy, the Koedam's scale for posterior atrophy, and the Pasquier's global cortical atrophy scale for frontal atrophy. A total of 89 AD patients showed a brain atrophy pattern consistent with typical AD; 30 patients showed a limbic-predominant pattern; 29 patients showed a hippocampal-sparing pattern; and 27 showed minimal atrophy. We built brain structural networks from 68 cortical regions and 14 subcortical gray matter structures for each AD subtype and for the controls, and we compared between-group measures of integration, segregation, and modular organization. At the global level, modularity was increased and differential modular reorganization was detected in the four subtypes. We also found a decrease of transitivity in the typical and hippocampal-sparing subtypes, as well as an increase of average local efficiency in the minimal atrophy and hippocampal-sparing subtypes. We conclude that the AD subtypes have a distinct signature of network disruption associated with their atrophy patterns and further extending to other brain regions, presumably reflecting the differential spread of neurofibrillary tangles. We discuss the hypothetical emergence of these subtypes and possible clinical implications.
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