Polycomb-mediated repression of paternal chromosomes maintains haploid dosage in diploid embryos of .

Complex mechanisms regulate gene dosage throughout eukaryotic life cycles. Mechanisms controlling gene dosage have been extensively studied in animals, however it is unknown how generalizable these mechanisms are to diverse eukaryotes. Here, we use the haploid plant to assess gene dosage control in its short-lived diploid embryo.

New hybrid reformations of peripheral CT angiography: do we still need axial images?

Purpose: To quantify the detectability of peripheral artery stenosis on hybrid CT angiography (CTA) reformations.

Methods: Hybrid reformations were developed by combining multipath curved planar reformations (mpCPR) and maximum intensity projections (MIP). Fifty peripheral CTAs were evaluated twice: either with MIP, mpCPR and axial images or with hybrid reformations only.

Enhanced voxelization and representation of objects with sharp details in truncated distance fields.

This paper presents a new method for voxelization of solid objects containing sharp details. Voxelization is a sampling process that transforms a continuously defined object into a discrete one represented as a voxel field. The voxel field can be used for rendering or other purposes, which often involve a reconstruction of a continuous approximation of the original object.

A cell architecture modeling system based on quantitative ultrastructural characteristics.

The architecture of living cells is difficult to describe and communicate; therefore, realistic computer models may help their understanding. 3D models should correspond both to qualitative and quantitative experimental data and therefore should include specific authoring tools such as appropriate visualization and stereological measures. For this purpose we have developed a problem solving environment for stereology-based modeling (PSE-SBM), which is an automated system for quantitative modeling of cell architecture.

Multipath curved planar reformation of the peripheral arterial tree in CT angiography.

The study was approved by the institutional review board, and informed consent was obtained. The purpose of the study was to prospectively quantify the angular visibility range, determine the existence of orthogonal viewing pairs, and characterize the conditions that cause artifacts in multipath curved planar reformations (MPCPRs) of the peripheral arterial tree in 10 patients (eight men and two women; mean age, 69 years; range, 54-80 years) with peripheral arterial occlusive disease. Percentage of segments with the maximal possible visibility score of 1 was significantly greater (odds ratio, 1.

3D distance fields: a survey of techniques and applications.

A distance field is a representation where, at each point within the field, we know the distance from that point to the closest point on any object within the domain. In addition to distance, other properties may be derived from the distance field, such as the direction to the surface, and when the distance field is signed, we may also determine if the point is internal or external to objects within the domain. The distance field has been found to be a useful construction within the areas of computer vision, physics, and computer graphics.

Magnetic resonance imaging of trabecular and cortical bone in mice: comparison of high resolution in vivo and ex vivo MR images with corresponding histology.

Measurements of bone morphometry and remodeling have been shown to reflect bone strength and can be used to diagnose degenerative bone disease. In this study, in vivo and ex vivo magnetic resonance imaging (MRI) techniques to assess trabecular and cortical bone properties have been compared to each other and to histology as a novel means for the quantification of bone. Femurs of C57Bl/6 mice were examined both in vivo and ex vivo on an 11.

Single point imaging with suppressed sound pressure levels through gradient-shape adjustment.

Acoustic noise produced during single point imaging (SPI) experiments was modulated by changes in the spatial encoding gradients. Parameters of both linear and sine-shaped gradient ramps were modified to minimize the acoustic noise levels. Acoustic noise measurements during SPI were measured on three different gradient systems and revealed that for small gradient-bore systems a considerable acoustic noise reduction of more than 20 dB can easily be achieved.

Magnetic resonance imaging of seeds by use of single point acquisition.

In general, magnetic resonance imaging (MRI) is used to obtain a spatial representation of the water distribution in an object. Water in soft materials (living matter) often shows a high degree of translational mobility, giving rise to relatively long magnetic relaxation times. This allows the use of conventional MRI techniques such as the spin-echo, to acquire an image.