Moving Past ‘One Size Fits All’: Developing a Trajectory Deviance Index for Dynamic Measurement Modeling

Dynamic Measurement Modeling (DMM) is a recently developed measurement framework for gauging developing constructs (e.g., learning capacity) that conventional single-timepoint tests cannot assess. Like most measurement models, overall model fit indices of DMM do not indicate the measurement appropriateness for each included student. For this reason, other measurement modeling paradigms (e.g., Item-Response Theory; IRT) utilize person-fit or model appropriateness statistics to indicate whether a measurement model appropriately describes the data from each individual student. However, within the extant DMM framework, no statistical index has yet been developed for this purpose. Thus, the current project advanced a person-specific DMM Trajectory Deviance Index (TDI) that captures the aberrance of an individual’s growth from the model-implied trajectory. Two simulation studies were conducted to examine and compare the distributional properties and effectiveness of four TDI candidates with different formulations. Consequently, the best functioning one was determined as the final formulation of the TDI. The data generation model was based on the parameter estimates from the Technology-enhanced, Research-based, Instruction, Assessment, and professional Development (TRIAD) cluster-randomized experiment data, which contains seven waves of mathematics test scores for students from pre-school through Grade 5. Besides the simulation work, an empirical study was also conducted to demonstrate the uses of the developed TDI within those real-world data. The results indicated that bilingual status was significantly related to the deviance of growth in early mathematics, whereas the other examined factors (i.e., intervention, age, gender, special education status, Socioeconomic status) were not. Incorporating TDI into DMM analysis strengthened the validity of score use and interpretation, and offered a quantitative means of determining which students in the dataset were not adequately served by the dynamic measurement model

Purchase or rent? Optimal pricing for 3D printing capacity sharing platforms

Online sharing platforms have attracted considerable research and management attention across a number of industries, including travel, real estate, and cloud computing. They also have great potential for the 3D printing (3DP) industry, offering users the choice between owning or renting 3DP capacity. For matching supply and demand, capacity pricing is crucial. In this paper we consider two fundamental questions concerning pricing: (i) What is the optimal pricing strategy for a 3DP capacity sharing platform? (ii) How do usage level and printer heterogeneity affect consumers’ choice between in-house printing (owning) and outsourcing (renting)? Using queuing analysis, we derive the structural properties of the solutions to the problems. Furthermore, we conduct numerical studies using real-world data to generate managerial insights from the analytical findings. A key finding is that governments should focus on encouraging technological progress to lower the printers’ prices in order to improve the well-being of the industry. When considering two types of printers, we find that it is more beneficial for the platform if the high capacity printer dominates the market, as the platform then retains the prominent role in “redistributing” the 3DP capacity.</p

Hydrogel-in-hydrogel live bioprinting for guidance and control of organoids and organotypic cultures

Three-dimensional hydrogel-based organ-like cultures can be applied to study development, regeneration, and disease in vitro. However, the control of engineered hydrogel composition, mechanical properties and geometrical constraints tends to be restricted to the initial time of fabrication. Modulation of hydrogel characteristics over time and according to culture evolution is often not possible. Here, we overcome these limitations by developing a hydrogel-in-hydrogel live bioprinting approach that enables the dynamic fabrication of instructive hydrogel elements within pre-existing hydrogel-based organ-like cultures. This can be achieved by crosslinking photosensitive hydrogels via two-photon absorption at any time during culture. We show that instructive hydrogels guide neural axon directionality in growing organotypic spinal cords, and that hydrogel geometry and mechanical properties control differential cell migration in developing cancer organoids. Finally, we show that hydrogel constraints promote cell polarity in liver organoids, guide small intestinal organoid morphogenesis and control lung tip bifurcation according to the hydrogel composition and shape

In-situ Formed Bioactive Stem Cell Hydrogel Dressings from PEG-based Multifunctional Copolymers for Wound Healing

Wound healing, especially chronic wound healing, has become a major clinical problem all over the world. Among all the treatments for wound healing, wound dressings are the main management approaches for both acute and chronic wounds. However, although significant progress has been made in the development of modern wound dressings over the past few years, there are still restrictions to stimulating the healing process. As an alternative to existing approaches, tissue engineering approaches with stem cell therapy have been widely studied for wound healing applications and showed promising therapeutic effects. Ideally, the next step is to develop a wound dressing with specific therapeutic functions such as delivering therapeutic agents (e.g. growth factors and/or stem cells) to promote the healing process. The overall goal of this doctoral project was to develop an injectable hydrogel cell delivery system which could easily encapsulate and support adipose-derived stem cells\u27 (ADSCs) growth, proliferation and secretion, with the potential use as a temporary bioactive hydrogel dressing for wound healing applications. To this end, the multifunctional PEG-based hyperbranched copolymers with thermoresponsive behavior and in-situ photo-/chemical cross-linkable properties have been developed via an advanced one-step in-situ deactivation enhanced atom transfer radical polymerization (DE-ATRP) method. At room temperature, this copolymer was water-soluble while forming a gel rapidly at body temperature, so that the cells can be easily encapsulated and applied to any wound size, shape or cavity, which is less invasive than other approaches and minimizes patients\u27 discomfort. In addition, a photo-/chemical gelation occurs within a short time to achieve a stable hydrogel with enhanced mechanical properties, supporting cell growth, proliferation and secretion. Furthermore, in combination with extracellular matrix (ECM) biopolymer of hyaluronic acid (HA), the microenvironment of the hydrogel system has been optimized during the project, so that the encapsulated ADSCs can maintain their viability and secretion level in vitro. Finally, the in vivo cell survival, material inflammatory response, and the wound healing effect of the optimized hydrogel system with rat ADSCs were evaluated using a rat dorsal excisional wound model. It was found that this system prevented the wound contraction and significantly enhanced angiogenesis. This is the first study to describe an injectable stem cell bioactive hydrogel dressing for wound healing purpose; and with the advanced multifunctional polymer and injectable hydrogel template developed in this project, there is significant potential for further development of this technique to the next step towards the realization of clinical wound healing applications ultimately.2017-07-3

Development and Calibration of the Student Opportunities for Deeper Learning Instrument

This article describes the development and calibration of the student opportunities for deeper learning instrument (SODLI). The SODLI is designed to measure the amount of learning opportunities intended to support higher‐order thinking that students are exposed to through student self‐report, and is expected to be widely useful in psychological research in schools. Here, the psychometric functioning of the SODLI is investigated in a relatively large sample of U.S. high‐school students (N = 963). Using multidimensional item‐response theory methods, a nine‐factor correlated model is determined to fit the data best, and to produce reliable estimates of SODLI dimensions. The SODLI is also shown to exhibit scalar‐invariant measurement properties across sex, race/ethnicity, and language‐background groups, although latent mean differences on some of the SODLI dimensions across those groups were identified

Encapsulation and 3d culture of human adipose-derived stem cells in an in-situ crosslinked hybrid hydrogel composed of peg-based hyperbranched copolymer and hyaluronic acid

Introduction: Cell therapy using adipose-derived stem cells has been reported to improve chronic wounds via differentiation and paracrine effects. One such strategy is to deliver stem cells in hydrogels, which are studied increasingly as cell delivery vehicles for therapeutic healing and inducing tissue regeneration. This study aimed to determine the behaviour of encapsulated adipose-derived stem cells and identify the secretion profile of suitable growth factors for wound healing in a newly developed thermoresponsive PEG-hyaluronic acid (HA) hybrid hydrogel to provide a novel living dressing system. Methods: In this study, human adipose-derived stem cells (hADSCs) were encapsulated in situ in a water-soluble, thermoresponsive hyperbranched PEG-based copolymer (PEGMEMA-MEO(2)MA-PEGDA) with multiple acrylate functional groups in combination with thiolated HA, which was developed via deactivated enhanced atom transfer radical polymerisation of poly(ethylene glycol) methyl ether methacrylate (PEGMEMA, Mn = 475), 2-(2-methoxyethoxy) ethyl methacrylate (MEO(2)MA) and poly(ethylene glycol) diacrylate PEGDA (Mn = 258). hADSCs embedded in the PEGMEMA-MEO(2)MA-PEGDA and HA hybrid hydrogel system (P-SH-HA) were monitored and analysed for their cell viability, cell proliferation and secretion of growth factors (vascular endothelial growth factor, transforming growth factor beta and placental-derived growth factor) and cytokines (IFN gamma, IL-2 and IL-10) under three-dimensional culture conditions via the ATP activity assay, alamarBlue (R) assay, LIVE/DEAD (R) assay and multiplex ELISA, respectively. Results: hADSCs were successfully encapsulated in situ with high cell viability for up to 7 days in hydrogels. Although cellular proliferation was inhibited, cellular secretion of growth factors such as vascular endothelial growth factor and placental-derived growth factor production increased over 7 days, whereas IL-2 and IFN gamma release were unaffected. Conclusion: This study indicates that hADSCs can be maintained in a P-SH-HA hydrogel, and secrete pro-angiogenic growth factors with low cytotoxicity. With the potential to add more functionality for further structural modifications, this stem cell hydrogel system can be an ideal living dressing system for wound healing applications

Impact of Rural Tourism Development on Subjective Well-Being Rural Chinese Woman

This exploratory study investigates the impact of tourism development on the subjective well-being of rural women in the suburban area of Jinan city, Shandong, China. Both qualitative and quantitative research methods were used to collect empirical data from rural women. According to the study findings, tourism development has reshaped rural Chinese female villagers\u27 daily lives and enhanced their subjective well-being in the context of urbanisation, land loss, and land use regulations in China\u27s rural areas. The study offers theoretical and practical implications. Suggestions for future research are also provided