87 research outputs found
More Knot Worms: Four New Polygordius (Annelida) Species from the Pacific and Caribbean
No full textPolygordius is a clade of marine annelids mainly seen in coarse-grained habitats. They are notable for their smooth bodies, lacking in chaetae or obvious segments, and they resemble Nematoda or Nemertea. Though Polygordius taxa are found in all oceans of the world, identifying species based only on morphological characters can be challenging due to their relatively uniform external appearances. Diversity within the clade has likely been markedly underestimated. Where morphological characters are inconspicuous or even unreliable, molecular methods can provide clarity in delimiting species. In this study, morphological methods (examination under light and scanning electron microscopy) were integrated with molecular analyses (sequencing of Cytochrome c oxidase subunit I, 16S rRNA and Histone H3 gene fragments) to establish the systematic placement of Polygordius specimens collected from Australia, Belize, French Polynesia, Indonesia, Japan, and the U.S. west coast. These analyses revealed three new species of Polygordius from the Pacific Ocean (P. erikae n. sp., P. kurthcarolae n. sp., and P. kurthsusanae n. sp.) as well as one new species from the Caribbean Sea (P. jenniferae n. sp.). These new species are formally described, and a previously known Japanese species, P. pacificus Uchida, 1936, is redescribed. This study establishes the first molecular data set for Polygordius species from the Pacific region, as well as the first formal description of a Caribbean species of Polygordius. Phylogenetic relationships within Polygordius are summarized and discussed
Properties of Reactively Sputter Deposited SrTiO<sub>3</sub> Films for IR Detector Readout Electronics
No full textABSTRACTThe effects of film thickness, oxygen partial pressure, electrode type, substrate temperature, and position on the room temperature and 77 K dielectric properties of SrTiO3 (ST) films were studied. The film composition and properties vary with radial position and oxygen partial pressure. A maximum in dielectric constant occurs near the same position where stoichiometric films are obtained. The room temperature and 77K dielectric constants increase with increasing thickness, while the capacitance density decreases. Capacitance densities as high as 4 fF/μm2 were observed for films deposited at low temperature and subsequently crystallized. Elevated temperature deposition, however, results in better properties than room temperature deposition followed by annealing. Dielectric constants as high as 200 with capacitance densities up to 9 fF/μ2 were observed. For optimized deposition conditions, no dielectric break-down of the capacitors was observed at 20V after 111 days of testing. The properties of capacitors with n+Si bottom electrodes were not as good as those with Ti/Pt electrodes, however, integration with Si integrated circuit processing is expected to be much simpler.</jats:p
An Open Source Multivariate Framework for n-Tissue Segmentation with Evaluation on Public Data
No full textThalamic connectivity in patients with essential tremor treated with MR imaging-guided focused ultrasound: in vivo fiber tracking by using diffusion-tensor MR imaging.
No full textPURPOSE: To use diffusion-tensor (DT) magnetic resonance (MR) imaging in patients with essential tremor who were treated with transcranial MR imaging-guided focused ultrasound lesion inducement to identify the structural connectivity of the ventralis intermedius nucleus of the thalamus and determine how DT imaging changes correlated with tremor changes after lesion inducement.
MATERIALS AND METHODS: With institutional review board approval, and with prospective informed consent, 15 patients with medication-refractory essential tremor were enrolled in a HIPAA-compliant pilot study and were treated with transcranial MR imaging-guided focused ultrasound surgery targeting the ventralis intermedius nucleus of the thalamus contralateral to their dominant hand. Fourteen patients were ultimately included. DT MR imaging studies at 3.0 T were performed preoperatively and 24 hours, 1 week, 1 month, and 3 months after the procedure. Fractional anisotropy (FA) maps were calculated from the DT imaging data sets for all time points in all patients. Voxels where FA consistently decreased over time were identified, and FA change in these voxels was correlated with clinical changes in tremor over the same period by using Pearson correlation.
RESULTS: Ipsilateral brain structures that showed prespecified negative correlation values of FA over time of -0.5 or less included the pre- and postcentral subcortical white matter in the hand knob area; the region of the corticospinal tract in the centrum semiovale, in the posterior limb of the internal capsule, and in the cerebral peduncle; the thalamus; the region of the red nucleus; the location of the central tegmental tract; and the region of the inferior olive. The contralateral middle cerebellar peduncle and bilateral portions of the superior vermis also showed persistent decrease in FA over time. There was strong correlation between decrease in FA and clinical improvement in hand tremor 3 months after lesion inducement (P < .001).
CONCLUSION: DT MR imaging after MR imaging-guided focused ultrasound thalamotomy depicts changes in specific brain structures. The magnitude of the DT imaging changes after thalamic lesion inducement correlates with the degree of clinical improvement in essential tremor
Statistical modeling of facial aging based on 3D scans
No full textThis thesis presents an approach to the modeling of facial aging using and extending the Morphable Model technique. For modeling the face variation across individuals, facial expressions, and physical attributes, we collected 3D face scans of 298 persons. The 3D face scans where acquired with a structured light 3D scanner, which we improved in collaboration with the manufacturer to achieve superior geometry and texture quality. Moreover, we developed an efficient way to measure fine skin structure and reflection properties with the scanner. The collected face scans have been used to build the Basel Face Model, a new publicly available Morphable Model.
Using the 3D scans we learn the correlation between physical attributes such as weight, height, and especially age and faces. With the learned correlation, we present a novel way to simultaneously manipulate different attributes and demonstrate the capability to model changes caused by aging. Using the attributes of the face model in conjunction with a skull model developed in the same research group, we present a method to reconstruct faces from skull shapes which considers physical attributes, as the body weight, age etc.
The most important aspect of facial aging that can not be simulated with the Morphable Model is the appearance of facial wrinkles. In this work we present a novel approach to synthesize age wrinkles based on statistics. Our wrinkle synthesis consists of two main parts: The learning of a generative model of wrinkle constellations, and the modeling of their visual appearance. For learning the constellations we use kernel density estimation of manually labeled wrinkles to estimate the wrinkle occurrence probability. To learn the visual appearance of wrinkles we use the fine scale skin structure captured with our improved scanning method. Our results show that the combination of the attribute fitting based aging and the wrinkle synthesis, facilitate a simulation of visually convincing progressive aging. The method is without restrictions applicable to any face that can be represented by the Morphable Model
In vivo imaging of canine lung deformation: Effects of posture, pneumonectomy, and inhaled erythropoietin.
No full textMechanical stresses on the lung impose the major stimuli for developmental and compensatory lung growth and remodeling. We used computed tomography (CT) to noninvasively characterize the factors influencing lobar mechanical deformation in relation to posture, pneumonectomy (PNX), and exogenous proangiogenic factor supplementation. Post-PNX adult canines received weekly inhalations of nebulized nanoparticles loaded with recombinant human erythropoietin (EPO) or control (empty nanoparticles) for 16 wk. Supine and prone CT were performed at two transpulmonary pressures pre- and post-PNX following treatment. Lobar air and tissue volumes, fractional tissue volume (FTV), specific compliance (Cs), mechanical strains, and shear distortion were quantified. From supine to prone. lobar volume and Cs increased while strain and shear magnitudes generally decreased. From pre- to postPNX, air volume increased less and FTV and Cs increased more in the left caudal (LCa) than in other lobes. FTV increased most in the dependent subpleural regions, and the portion of LCa lobe that expanded laterally wrapping around the mediastinum. Supine deformation was nonuniform pre- and post-PNX; strains and shear were most pronounced in LCa lobe and declined when prone. Despite nonuniform regional expansion and deformation, post-PNX lobar mechanics were well preserved compared with pre-PNX because of robust lung growth and remodeling establishing a new mechanical equilibrium. EPO treatment eliminated posture-dependent changes in FTV, accentuated the post-PNX increase in RN, and reduced FTV heterogeneity without altering absolute air or tissue volumes, consistent with improved microvascular blood volume distribution and modestly enhanced post-PNX alveolar microvascular reserves
Neuroimaging Evidence of Major Morpho-Anatomical and Functional Abnormalities in the BTBR T+TF/J Mouse Model of Autism
No full textBTBR T+tf/J (BTBR) mice display prominent behavioural deficits analogous to the defining symptoms of autism, a feature that has prompted a widespread use of the model in preclinical autism research. Because neuro-behavioural traits are described with respect to reference populations, multiple investigators have examined and described the behaviour of BTBR mice against that exhibited by C57BL/6J (B6), a mouse line characterised by high sociability and low self-grooming. In an attempt to probe the translational relevance of this comparison for autism research, we used Magnetic Resonance Imaging (MRI) to map in both strain multiple morpho-anatomical and functional neuroimaging readouts that have been extensively used in patient populations. Diffusion tensor tractography confirmed previous reports of callosal agenesis and lack of hippocampal commissure in BTBR mice, and revealed a concomitant rostro-caudal reorganisation of major cortical white matter bundles. Intact inter-hemispheric tracts were found in the anterior commissure, ventro-medial thalamus, and in a strain-specific white matter formation located above the third ventricle. BTBR also exhibited decreased fronto-cortical, occipital and thalamic gray matter volume and widespread reductions in cortical thickness with respect to control B6 mice. Foci of increased gray matter volume and thickness were observed in the medial prefrontal and insular cortex. Mapping of resting-state brain activity using cerebral blood volume weighted fMRI revealed reduced cortico-thalamic function together with foci of increased activity in the hypothalamus and dorsal hippocampus of BTBR mice. Collectively, our results show pronounced functional and structural abnormalities in the brain of BTBR mice with respect to control B6 mice. The large and widespread white and gray matter abnormalities observed do not appear to be representative of the neuroanatomical alterations typically observed in autistic patients. The presence of reduced fronto-cortical metabolism is of potential translational relevance, as this feature recapitulates previously-reported clinical observations
Computational analysis of HRCT images for characterization and differentiation of ILD and COPD
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