多层螺旋CT二维法测量肱骨头扭转角探讨

目的:探讨肱骨头扭转角多层螺旋CT二维测量方法,着重讨论肱骨头扭转角远端定义线对测值的影响。方法:收集51根肱骨干标本,行16层螺旋CT扫描,肱骨头中轴线与肱骨远端前关节面的切线,或内外上髁连线的夹角为肱骨头扭转角。肱骨远端定义线取上中下三个不同平面得到六组肱骨头扭转角度数,进行统计学处理。结果:肱骨头扭转角最小值4°,最大值59.8°,六组肱骨头扭转角数据分别为:(27.9±11.9)°、(29.2±11.2)°、(30.2±10.7)°、(27.3±10.3)°、(26.3±10.2)°、(25.8±10.4)°,经统计学处理,以肱骨远端前关节面切线为远端定义线测得肱骨头扭转角度数越往远端越大;而以肱骨内外上髁连线为远端定义线测得的值越往远端越小;肱骨远端下方层面两种定义线测得肱骨头扭转角有显著性差异,其余层面所得值无差异,上部层面两种定义线肱骨扭转角均数最为接近,相差仅0.6°。结论:肱骨头扭转角变异较大,肩关节假体扭转角设计应个性化;多层螺旋CT二维法测量肱骨头扭转角应取鹰嘴窝较深且显示肱骨远端前关节面清楚的层面做为远端定义层面。     

智慧动物与电子科技交互：现状与展望

人类与动物的交互合作自古以来就有着悠久的历史,伴随着智能芯片、可穿戴设备和机器算法的快速发展,智慧动物与电子科技的交互成为了现实。如今,人类可以借助电子系统与动物进行沟通、感知和控制。这类电子设备的目标在于实现以动物为中心的工作模式,从而提升人类对动物的理解,最终促进动物智能和创造力的发展。本文将中型、大型动物作为研究对象,以发展其能力增强为目标,提出了“智慧动物增强系统”的构想。该构想用以描述这类装置的特性,并对现有的动物与计算机接口解决方案进行了全面综述。总的来说,智慧动物增强系统主要分为植入式和非植入式两类,均由接口平台、感知与解读、控制与指示三部分构成,并通过不同层次的增强系统和架构模式,从而实现人与动物的智慧交互。尽管已有的智慧动物增强系统仍然缺乏完整独立的交互系统架构,但在未来的发展中,智慧动物增强系统具备良好的前景和发展空间,不仅可以用于替代尖端设备和运输设备,还有望通过智慧共联实现跨物种的信息交互。同时,智慧动物增强系统可以促进人与动物的双向交互,对动物伦理和生态保护的发展也将产生重要的推动作用。更为重要的是,基于动物主体的交互模型开发能够为设计人机交互系统提供可借鉴的...     

Zero-inflated Poisson models with measurement error in the response

Zero-inflated count data arise frequently from genomics studies. Analysis of such data is often based on a mixture model which facilitates excess zeros in combination with a Poisson distribution, and various inference methods have been proposed under such a model. Those analysis procedures, however, are challenged by the presence of measurement error in count responses. In this article, we propose a new measurement error model to describe error-contaminated count data. We show that ignoring the measurement error effects in the analysis may generally lead to invalid inference results, and meanwhile, we identify situations where ignoring measurement error can still yield consistent estimators. Furthermore, we propose a Bayesian method to address the effects of measurement error under the zero-inflated Poisson model and discuss the identifiability issues. We develop a data-augmentation algorithm that is easy to implement. Simulation studies are conducted to evaluate the performance of the proposed method. We apply our method to analyze the data arising from a prostate adenocarcinoma genomic study.     

Hardiness dependent accumulation of phospholipids in leaves of wheat cultivars

Phospholipid content and composition in the leaves of thirteen cultivars of wheat differing in frost hardiness, were compared before and after hardening in order to see whether phospholipids play a role in surviving at low temperatures. The content of phospholipids in the leaves at the end of the hardening could be related to the aquired hardiness, and the relationship between the two phenomena could be described by the regression equation y = (0.174 ± 0.0016) x + 1311. Accumulation of phospholipids represents a hardiness dependent augmentation of membranes. Phosphatidylcholine appeared to be preferentially accumulated in hardy cultivars during the hardening process. As there are no significant differences in phospholipid fatty acid compositions investigated earlier, these results suggest the importance of the polar head group composition of membranes in avoiding frost injury.     

Seasonal abundance of the crapemyrtle aphid,Sarucallis kahawaluokalani,in relation to the pecan aphids,Monellia caryella andMonelliopsis pecanis and their common predators

The seasonal abundance of the crapemyrtle aphid,Sarucallis kahawaluokalani (Kirkaldy), and the majority of its predators that are common with the yellow pecan aphid,Monelliopsis pecanis Bissel, and the blackmargined aphid,Monellia caryella (Fitch), were determined in norh Florida.S. kahawaluokalani populations were tri — and bimodal in the 2 years studied and peak populations ofS. kahawaluokalani preceeded those of the pecan aphid complex. Peaks in predator populations consisting of Coccinellidae, Syrphidae, Chrysopidae and Anthocoridae, either coincided with or occurred just afterS. kahawaluokalani peaks. The implications of the findings with respect to use ofS. kahawaluokalani as an alternate host of predators of pecan aphids and the potential for manipulation of the system to enhance biological control in pecan are discussed. The use of this system is advocated for augmentation and manipulation of generalist predators in other crop systems. Florida Agricultural Experiment Station Journal Series N^o 7294.     

Finite Element Analysis as a Tool for Parametric Prosthetic Foot Design and Evaluation. Technique Development in the Solid Ankle Cushioned Heel (SACH) Foot

In this study, we developed an approach for prosthetic foot design incorporating motion analysis, mechanical testing and computer analysis. Using computer modeling and finite element analysis, a three-dimensional (3D), numerical foot model of the solid ankle cushioned heel (SACH) foot was constructed and analyzed based upon loading conditions obtained from the gait analysis of an amputee and validated experimentally using mechanical testing. The model was then used to address effects of viscoelastic heel performance numerically. This is just one example of the type of parametric analysis and design enabled by this approach. More importantly, by incorporating the unique gait characteristics of the amputee, these parametric analyses may lead to prosthetic feet more appropriately representing a particular user's needs, comfort and activity level.     

Shape Optimization of a Cementless Hip Stem for a Minimum of Interface Stress and Displacement

The primary stem stability is an essential factor for success of cementless hip stems. A correct choice of the stem geometry can improve the stem stability and, consequently, increase the life time of a hip implant. In this work, it is proposed a computational model for shape optimization of cementless hip stems. The optimization problem is formulated by the minimization of relative displacement and stress on bone/stem interface using a multi-criteria objective function. Also multiple loads are considered to incorporate several daily life activities. Design variables are parameters that characterize the geometry of selected cross sections, which are subject to geometric constraints to ensure a clinically admissible shape. The stem/bone set is considered a structure in equilibrium with contact conditions on interface. The contact formulation allows us to analyze different lengths of porous coating. The optimization problem is solved numerically by a steepest descent method. The interface stress and relative displacement are obtained solving the contact problem by the finite element method. Numerical examples are presented for a two-dimensional model of a hip stem, however, the formulation is general and can be applied to the three-dimensional case. The model gives indications about the relation between shape, porous coating and prosthesis stability.     

Bayesian nonparametric regression analysis of data with random effects covariates from longitudinal measurements

We consider nonparametric regression analysis in a generalized linear model (GLM) framework for data with covariates that are the subject-specific random effects of longitudinal measurements. The usual assumption that the effects of the longitudinal covariate processes are linear in the GLM may be unrealistic and if this happens it can cast doubt on the inference of observed covariate effects. Allowing the regression functions to be unknown, we propose to apply Bayesian nonparametric methods including cubic smoothing splines or P-splines for the possible nonlinearity and use an additive model in this complex setting. To improve computational efficiency, we propose the use of data-augmentation schemes. The approach allows flexible covariance structures for the random effects and within-subject measurement errors of the longitudinal processes. The posterior model space is explored through a Markov chain Monte Carlo (MCMC) sampler. The proposed methods are illustrated and compared to other approaches, the "naive" approach and the regression calibration, via simulations and by an application that investigates the relationship between obesity in adulthood and childhood growth curves.     

Impacts of Channel Reconstruction on Invertebrate Assemblages in a Restored River

Ecosystem restoration often aims to recreate the physical habitat needed to support a particular life‐stage of a focal species. For example, river channel reconstruction, a common restoration practice along the Pacific coast, is typically used to enhance spawning habitat for adult Chinook salmon, a species experiencing large population declines. These restoration efforts rarely consider, however, that altering spawning habitat could have indirect effects on other life‐stages, such as juveniles, which might occur if, e.g. reconstruction alters the benthic food web. To determine how channel reconstruction impacts benthic macroinvertebrates, juvenile Chinook's primary prey, we conducted two studies at a restoration site in the Merced River, California. We asked (1) has gravel enhancement altered invertebrate assemblages in the restored reach compared with an unrestored reach? and, if so, (2) can shifts in the invertebrate community be explained by increased substrate mobility and by reduced heterogeneity that results from restoration? We show that invertebrate abundance and biomass were lower in the restored reach and that these changes were accompanied by a shift from dominance by filter‐feeding caddisflies (Hydropsyche) in the unrestored reach to grazing mayflies (Baetis) in the restored reach. Using an in situ manipulation, we demonstrated that this trend was driven by increased substrate mobility that reduces the abundance of Hydropsyche and by decreased substrate heterogeneity that reduces the abundance of Baetis. Our studies suggest that geomorphic changes typical of reconstructed rivers can alter food webs in ways that may have important implications for supporting the focal species of restoration efforts.