Search results for "Morphometry"

Examining stability of independent component analysis based on coefficient and component matrices for voxel-based morphometry of structural magnetic …

2018

Independent component analysis (ICA) on group-level voxel-based morphometry (VBM) produces the coefficient matrix and the component matrix. The former contains variability among multiple subjects for further statistical analysis, and the latter reveals spatial maps common for all subjects. ICA algorithms converge to local optimization points in practice and the mostly applied stability investigation approach examines the stability of the extracted components. We found that the practically stable components do not guarantee to produce the practically stable coefficients of ICA decomposition for the further statistical analysis. Consequently, we proposed a novel approach including two steps: …

An integrated approach to the study of Hypericum occurring in Sicily

2020

An integrated approach to the study of taxa of the genus Hypericum occurring in Sicily is proposed. The results of morphological, biochemical, and molecular analyses are combined to better assess the relationships between the species investigated and test the suitability of DNA barcoding technique in the discrimination of these taxa. For the name Hypericum aegypticum subsp. webbii (Spach) N. Robson a lectotype is designated. For Hypericum triquetrifolium Turra a lectotype and a supporting epitype are designated. The presence of Hypericum perforatum L. subsp. perforatum is excluded from Sicily and the previous reports have to be referred to H. perforatum subsp. veronense (Schrank) Ces. Hyper…

Caratterizzazione biometrica e stima numerica di una popolazione di testuggine palustre siciliana.

2008

A taxonomic reassessment of the Centaurea busambarensis complex (Compositae, Cardueae), with description of a new species from the Egadi Islands (W S…

2017

The results of a statistical biometric study of the Centaurea busambarensis complex, which represents the C. cineraria aggregate in Sicily and its offshore islets, are presented. Seventeen populations, representing all seven previously recognized taxa (four species and three additional subspecies) plus a presumed undescribed one were studied. The statistical analysis (PCA and DA) of 26 morphological characters confirmed these eight taxa as distinct, geographically or ecologically vicarious units of equal weight, not supporting their treatment at different ranks. Consequently, they are recognized here as species, resulting in the description (with illustration) of one of them as new (C. aegu…

Drumlins and related glaciogenic landforms of the Madliena Tilted plain, Central Latvian Lowland

2012

This paper presents new results on the morphometry and spatial distribution of the glaciogenic landforms and ice flow directions in the Madliena Tilted Plain that occupies the eastern part of the Central Latvian Lowland. Landforms were investigated by using topographic maps at scales of 1:25 000 and 1:10 000. There were identified and mapped 1461 glaciogenic landforms such as drumlins, end moraine ridges, eskers, ribbed moraines, marginal ridges, lateral shear margin moraines and recessional formations. Particular attention is given to the morphometry, spatial distribution, and the internal structure of drumlins. Glacial landscape of the study area was formed by the Zemgale ice lobe in cour…

Estudio de los taxa afines a Limonium vulgare Miller de marismas de Portugal Continental

2012

Master de Biodiversidad: Conservacion y evolucion - Universitat de Valencia. Facultat de Ciencies Biologiques / Instituto Superior de Agronomia The genus Limonium Miller is a highly complex taxonomic group and a large number of micro-species has been described as a result of their reproductive strategies, sexual and/or apomixis. In Portugal, there are few and old studies on Limonium species, although the country has exceptional conditions for their presence, given that they inhabit rocky cliffs, beaches and salt-marshes. This study was intended to clarify the identity of ambiguous specimens related to taxon Limonium vulgare Miller, typical in the salt-marshes of Continental Portugal. We per…

Increasing temperature and productivity change biomass, trophic pyramids and community‐level omega‐3 fatty acid content in subarctic lake food webs

2021

Climate change in the Arctic is outpacing the global average and land-use is intensifying due to exploitation of previously inaccessible or unprofitable natural resources. A comprehensive understanding of how the joint effects of changing climate and productivity modify lake food web structure, biomass, trophic pyramid shape and abundance of physiologically essential biomolecules (omega-3 fatty acids) in the biotic community is lacking. We conducted a space-for-time study in 20 subarctic lakes spanning a climatic (+3.2 degrees C and precipitation: +30%) and chemical (dissolved organic carbon: +10 mg/L, total phosphorus: +45 mu g/L and total nitrogen: +1,000 mu g/L) gradient to test how temp…

Brain Structure MR Imaging Methods: Morphometry and Tractography

2013

Brain morphology is in constant change from the very beginning of the neurodevelopment in human beings. The characterization of the brain morphology and its biological implications on a specific subject is a complex task which requires efficient computational approaches. Radiology has traditionally assessed the main brain changes in different alterations from a macroscopic point of view, thus, not considering subtle changes as a results of neuronal plasticity. In conjunction with functional information, the structural neuroimaging methods have established as the key in the diagnosis of several central nervous system disorders, including tumours, neurodegenerative disorders and psychiatric d…

2020

Regular physical activity (PA) offers positive effects on the human body. However, the effects of PA on cognition and in the brain are less clear. In this paper, we narratively review the relationship of PA with cognition and dementia, first from general perspective and then through genetically informed studies on the topic. Then we move on to imaging studies on exercise and brain anatomy first by presenting an overall picture of the topic and then discussing brain imaging studies addressing PA and brain structure in twins in more detailed way. Regarding PA and cognition or dementia, genetically informed studies are uncommon, even though the relationship between PA and cognitive ageing has …

Neuroanatomical changes in early Parkinson’s disease with mild cognitive impairment: a VBM study; the Parkinson’s Disease Cognitive Impairment Study …

2021

Introduction: Mild cognitive impairment (MCI) is common in Parkinson’s disease (PD), but the underlying pathological mechanism has not been fully understood. Voxel-based morphometry could be used to evaluate regional atrophy and its relationship with cognitive performances in early PD-MCI. Patients and Methods: One hundred and six patients with PD were recruited from a larger cohort of patients, the Parkinson’s Disease Cognitive Impairment Study (PaCoS). Subject underwent a T1-3D MRI and a complete clinical and neuropsychological evaluation. Patients were divided into PD with normal cognition (PD-NC) and PD-MCI according to the MDS level II criteria–modified for PD-MCI. A subgroup of early …