Increased awareness of the economic and social effects of aging, deterioration and extreme events on civil infrastructure has been accompanied by recognition of the need for advanced structural health monitoring and damage detection tools. Today, these tasks are done by visual inspection and very traditional methods such as the tap test. This labor-intensive task is done at a frequency of less than once every two years for bridges, and on an as-needed basis for other infrastructures such as buildings. Structural health monitoring techniques based on changes in dynamic characteristics have been studied for the last three decades. When the damage is substantial, these methods have some success in determining if damage has occurred. At incipient stages of damage, however, the existing methods are not as successful. A number of new research projects have been funded to improve the damage detection methods including the use of innovative signal processing, new sensors, and control theory. This survey paper highlights these new research directions.

Summary The ability to generate T cells from self-renewing pluripotent stem cells (PSC) has the potential to transform the current practice of autologous T cell immunotherapy into universal off-the-shelf products. However, differentiation of human PSCs into mature, conventional T cells has been challenging with existing methods. We report that a 3D artificial thymic organoid (PSC-ATO) system induced efficient differentiation of human embryonic stem cell and induced pluripotent stem cell-derived mesoderm progenitors to mature, functional T cells with a diverse T cell receptor (TCR) repertoire. This continuous culture system supported both hematopoietic specification and terminal differentiation to naïve CD3+CD8αβ+ and CD3+CD4+ conventional T cells. Introduction of an MHC class I-restricted TCR in PSCs produced naïve, antigen-specific cytotoxic CD8αβ+ T cells which lacked endogenous TCR Vβ expression. Functional assays and RNA sequencing aligned PSC-derived T cells with primary naïve CD8+ T cells. The PSC-ATO system presented here is an efficient platform for generating functional, mature T cells from human PSCs.

Purpose: To test the hypothesis that there is greater asymmetry in diffusion properties between right and left pyramidal tracts in patients with congenital hemiparesis than in patients with normal motor function. Materials and Methods:Four congenitally hemiparetic patients and four age-matched controls underwent magnetic resonance diffusion tensor imaging (DTI)-based three-dimensional tractography of the pyramidal tracts. Relative anisotropy, individual eigenvalues, and directionally averaged apparent diffusion coefficient were measured and degree of asymmetry was calculated.Results: Compared with age-matched controls, congenitally hemiparetic patients had greater asymmetry in all measured diffusion properties. The asymmetry was characterized primarily by lower anisotropy, lower parallel diffusion, higher transverse diffusion, and slightly higher mean diffusivity in the pyramidal tract contralateral to the hemiparesis (i.e., affected pyramidal tract) compared with the unaffected pyramidal tract.Conclusions: There appears to be greater diffusion asymmetry between the pyramidal tracts in congenitally hemiparetic patients compared to controls. These differences suggest that there are alterations in the microstructure of the pyramidal tract that controls the motor function of the hemiparetic side. Our results suggest that DTI-based three-dimensional tractography is potentially useful in the assessment of motor dysfunction in infants and children with congenital hemiparesis.

No abstract

Accurate modeling of large rubber deformations is now possible with finiteelement codes. Many of these codes have certain strain-energy functions built-in, but it can be difficult to get the relevant material parameters and the behavior of the different built-in functions have not been seriously evaluated. In this article, we show the benefits of assuming a Valanis-Landel (VL) form for the strain-energy function and demonstrate how this function can be used to enlarge the data set available to fit a polynomial expansion of the strain-energy function. Specifically, we show that in the ABAQUS finite-element code the Ogden strain-energy density function, which is a special form of the VL function, can be used to provide a planar stress-strain data set even though the underlying data used to determine the constants in the strain-energy function include only uniaxial data. Importantly, the polynomial strain-energy density function, when fit to the uniaxial data set alone, does not give the same planar stress-strain behavior as that predicted from the VL or Ogden models. However, the polynomial form does give the same planar response when the VL-generated planar data are added to the uniaxial data set and fit with the polynomial strain-energy function. This shows how the VL function can provide a reasonable means of estimating the three-dimensional strain-energy density function when only uniaxial data are available.