We propose generalizations of a number of standard network models, including the classic random graph, the configuration model, and the stochastic block model, to the case of time-varying networks. We assume that the presence and absence of edges are governed by continuous-time Markov processes with rate parameters that can depend on properties of the nodes. In addition to computing equilibrium...

Microscale tipstreaming is a hydrodynamic phenomenon capable of producing submicron sized droplets within a microfluidic device. Tipstreaming is the ejection of small drops from a liquid thread formed by interfacial tension gradients and convective transport of surfactant. To use tipstreaming in potential applications, including nanoparticle synthesis, chemical detection and separation, occlusi...

This paper presents an analysis of some of the significant developments in time-varying network theory which have taken place during the past decade, with the emphasis placed on three topics: 1) characterization of time-varying networks, and in particular, transition from the impulsive response to the differential equation; 2) the problem of factorization, with emphasis on the contributions of ...

We report an injectable hydrogel scaffold system with tunable stiffness for controlling the proliferation rate and differentiation of human mesenchymal stem cells (hMSCs) in a three-dimensional (3D) context in normal growth media. The hydrogels composed of gelatin-hydroxyphenylpropionic acid (Gtn-HPA) conjugate were formed using the oxidative coupling of HPA moieties catalyzed by hydrogen perox...

Hydrogels can promote desirable cellular phenotype by mimicking tissue-like stiffness or serving as a gene delivery depot. However, nonviral gene delivery inside three-dimensional (3D) hydrogels remains a great challenge, and increasing hydrogel stiffness generally results in further decrease in gene delivery efficiency. Here we report a method to enhance nonviral gene delivery efficiency insid...

The a relaxation of a series of ether–ketone model compounds was studied to quantify the effect of molecular stiffness on the Kohlrausch–Williams–Watts stretching exponential. The obtained values decrease with increasing stiffness and are within the theoretical bounds predicted for systems with spatial dimensionality varying from 2 to 1. © 2000 American Institute of Physics. @S0021-9606~00!5151...

BACKGROUND The association between hypothyroidism and increased vascular resistance, arterial wall thickening and endothelial dysfunction is well recognized. The aim of the present study was to examine if hypothyroid subjects have increased arterial stiffness, a risk factor for cardiovascular morbidity and mortality. METHODS Sixty-five subjects (59 females and 6 males) with normal thyroid fun...

This paper presents a two-part study of the effects of virtual surface stiffness on haptic perception. First, size identification experiments were performed to determine the effects of system quality, in terms of surface stiffness, on the ability of a human to identify square cross-section ridges by size in a simulated environment. Then, discrimination experiments were performed to determine re...

We believe that the lateral exploration of surfaces with varying stiffness, stiffness maps, using computer generated haptics is an underestimated and important procedure with impact in many application areas. Feeling the change of stiffness while sweeping the haptic probe over a surface can potentially give an understanding of the spatial distribution of this stiffness, however current algorith...

Reductionist in vitro model systems which mimic specific extracellular matrix functions in a highly controlled manner, termed artificial extracellular matrices (aECM), have increasingly been used to elucidate the role of cell-ECM interactions in regulating cell fate. To better understand the interplay of biophysical and biochemical effectors in controlling three-dimensional cell migration, a po...