Formats of image data files that can be used in routine digital light micrography. Part two

This is part two of an article that describes the properties of the image data files that are encountered routinely in digital light micrography. In the current part of the article, the differences between saving image data as large intact files and smaller files that have had some information removed, i.e., using lossy compression, are related first. Subsequently, appropriate ways of configuring computers to deal with the large intact image data files are suggested. The structures of the image data files used for recording dynamic sequences and kinematic animations of series of digital light micrographs, i.e., movie formats, are then described. Finally, some information is supplied about choosing file formats for compressing both static and dynamic image data sets.     

Changes in the Fabric and Compliance Tensors of Cancellous Bone due to Trabecular Surface Remodeling,Predicted by a Digital Image-based Model

Fabric and compliance tensors of a cube of cancellous bone with a complicated three-dimensional trabecular structure were obtained for trabecular surface remodeling by using a digital image-based model combined with a large-scale finite element method. Using mean intercept length and a homogenization method, the fabric and compliance tensors were determined for the trabecular structure obtained in the computer remodeling simulation. The tensorial quantities obtained indicated that anisotropic structural changes occur in cancellous bone adapting to the compressive loading condition. There were good correlations between the fabric tensor, bone volume fraction, and compliance tensor in the remodeling process. The result demonstrates that changes in the structural and mechanical properties of cancellous bone are essentially anisotropic and should be expressed by tensorial quantities.     

Musculoskeletal modeling of user groups for virtual product and process development

Abstract

Although biomechanical digital human models find their way into virtual engineering processes, biomechanical considerations are currently still unrecognized to a large extent. One major obstacle lies in the fact that even though subject-specific modeling procedures are developed, virtual user groups or populations are still missing. The objective of this contribution is to create such groups of musculoskeletal models. Therefore, a modeling procedure based upon population data is described. First of all, two generic three-dimensional models, one with female and one with male average anthropometric dimensions, were obtained. These models constitute the starting point for the following model adjustment phases. Evenly distributed dimensionless values for gender, age, height, mass, range of motion and strength are sampled and translated into more expressive parameters for the mentioned modeling domains serving as input data for the creation of each individual model of the desired population or user group. The most sophisticated step of the adaption is the strength mapping aiming to create models matching arbitrary target joint torques. Finally, the models’ maximal strength is assessed in a manual material handling task and compared to empirical strength data. The approach is shown using the example of the German population.     

Sexual dimorphism in digital dermatoglyphic traits among Sinhalese people in Sri Lanka

Background

The purpose of this study was to evaluate gender-wise diversity of digital dermatoglyphic traits in a sample of Sinhalese people in Sri Lanka.

Findings

Four thousand and thirty-four digital prints of 434 Sinhalese individuals (217 males and 217 females) were examined for their digital dermatoglyphic pattern distribution. The mean age for the entire group was 23.66 years (standard deviation = 4.93 years). The loop pattern is observed more frequently (n = 2,592, 59.72%) compared to whorl (n = 1,542, 35.53%) and arch (n = 206, 4.75%) in the Sinhalese population. Females (n = 1,274, 58.71%) have a more ulnar loop pattern than males (n = 1,231, 56.73%). The plain whorl pattern is observed more frequently in males (n = 560, 25.81%) compared to females (n = 514, 23.69%).The double loop pattern is observed more frequently on the right and left thumb (digit 1) of both males and females. Pattern intensity index, Dankmeijer index and Furuhata index are higher in males.

Conclusions

Ulnar loop is the most frequently occurring digital dermatoglyphic pattern among the Sinhalese. All pattern indices are higher in males. To some extent, dermatoglyphic patterns of Sinhalese are similar to North Indians and other Caucasoid populations. Further studies with larger sample sizes are recommended to confirm our findings.     

Fine-scale vertical position as an indicator of vegetation in alkali grasslands – Case study based on remotely sensed data

Vertical position is an important driver of vegetation zonation at multiple scales, via determining abiotic environmental parameters, such as climate, soil properties and water balance. In inland alkali landscapes, elevation is a key factor for understanding patterns of salt accumulation and water table which is therefore considered a good indicator of alkali vegetation types. Remote sensing techniques offer viable solutions for linking elevation data to vegetation patterns by providing an elevation model of extended areas. Our goal was to test the relationships between fine-scale differences in vertical position and vegetation patterns in inland alkali landscapes by vegetation data collected in the field and elevation data generated using airborne laser scanning (ALS). We studied whether vertical position influences vegetation patterns at the level of main vegetation groups (based on alliances) or even at the level of associations. Our study sites were situated in a lowland alkali landscape in Hortobágy National Park (East-Hungary). We grouped the associations into four main vegetation groups: loess grasslands, alkali steppes, open alkali swards and alkali meadows. Even though we detected a very limited range (121 cm) in the vertical position of the main vegetation groups, they were well separated by their vertical positions. At the level of associations, a more detailed elevation-based distinction was also possible in many cases. The revealed elevation–vegetation correlations show that high-resolution mapping based on ALS remote sensing techniques is an ideal solution in complex lowland areas, such as alkali landscapes. Our findings suggest that in other types of lowland landscapes, characterised by elevation differences, the applied method might hold a great potential as a supporting tool for vegetation mapping.     

脑发育性静脉畸形9例临床影像特征分析及文献复习

目的:研究脑发育性静脉畸形(Cerebral Developmental Venous Anomalies,CDVA)临床及影像学特征及复习CDVA文献。方法:回顾性收集了自2011年11月至2014年3月我科确诊的9例CDVA的病人,对其临床特征、影像学检查方法包括电子计算机断层扫描(Computed Tomography,CT)、核磁共振成像(Magnetic Resonance Imaging,MRI)、数字减影血管造影(Digital Subtraction Angiography,DSA)及特征进行分析并对相关文献进行复习。结果:(1)临床症状:9例病人的临床症状包括头晕4例(4/9)、头痛4例(4/9)、恶心不适2例(2/9)、站立不稳1例((1/9)、小脑出血史1例(1/9)、眼部症状行眼科检查偶然发现小脑CDVA1例(1/9);(2)病变部位:病变位于幕上4例(4/9);幕下5例(5/9);(3)影像学检查:9例病人中,6例行CT平扫或增强扫描(3例平扫,3例平扫+增强);4例行MRI(1例平扫,3例平扫+增强);3例行DSA检查;(4)影像学特点:CT增强及重建、MRI的T1WI增强、SWI、MRA及DSA静脉期像均可显示出髓静脉及其形成的特征性"海蛇头"征象和其引流静脉。结论:CT、MRI、DSA影像学方法均可用于CDVA的诊断,在临床实践中需根据需要优化选择联合应用。     

A Monte Carlo study of the influence of focal spot size,intensity distribution,breast thickness and magnification on spatial resolution of an a-Se digital mammography system using the generalized MTF

In this study the generalized Modulation Transfer Function (GMTF) and the geometric sharpness (S_geo) were used (i) to study the effects of various focal spot sizes (0.04 mm–0.3 mm), x-ray intensity distributions (Gaussian and double Gaussian), breast thicknesses (2–7 cm) and magnifications M (1.0–2.0) on the spatial resolution of an a-Se digital mammography system, (ii) to identify suitable focal spots for magnification mammography and (iii) derive optimum magnifications. For the calculation of GMTF the required components were: focal spot MTF, obtained from theory, detector MTF, scatter MTF and scatter fraction obtained from Monte Carlo simulations. The results showed that focal spots with sizes up to 0.18 mm are suitable for magnification mammography offering a GMTF which is >50% and >20% at the respective object frequencies of 6.5 mm⁻¹ and 9 mm⁻¹. Focal spots with sizes < 0.16 mm and Gaussian. intensity distribution, or sizes ≤ 0.1 mm and double Gaussian, offer a system resolution which improves or does not deteriorate with magnification for most object frequencies. For larger focal spots, i.e. 0.16–0.18 mm for a Gaussian and 0.12–0.18 mm for a double Gaussian. intensity distribution, optimum magnifications exist which depend on the object frequency and breast thickness. System resolution (in terms of S_geo) is maximized at M = 1.8–2.0 (all breast thicknesses) for Gaussian intensity distribution, and at M = 1.4–1.6 (breast thicknesses ≤ 4 cm) and M = 1.6–1.8 (thicker breasts) for double Gaussian.