Objective:
To examine the relationship between experienced mental workload and physiological response by noninvasive monitoring of physiological parameters.
Background:
Previous studies have examined ...how individual physiological measures respond to changes in mental demand and subjective reports of workload. This study explores the response of multiple physiological parameters and quantifies their added value when estimating the level of demand.
Method:
The study presented was conducted in laboratory conditions and required participants to perform a visual-motor task that imposed varying levels of demand. The data collected consisted of physiological measurements (heart interbeat intervals, breathing rate, pupil diameter, facial thermography), subjective ratings of workload (Instantaneous Self-Assessment Workload Scale ISA and NASA-Task Load Index), and the performance.
Results:
Facial thermography and pupil diameter were demonstrated to be good candidates for noninvasive workload measurements: For seven out of 10 participants, pupil diameter showed a strong correlation (R values between .61 and .79 at a significance value of .01) with mean ISA normalized values. Facial thermography measures added on average 47.7% to the amount of variability in task performance explained by a regression model. As with the ISA ratings, the relationship between the physiological measures and performance showed strong interparticipant differences, with some individuals demonstrating a much stronger relationship between workload and performance measures than others.
Conclusion:
The results presented in this paper demonstrate that physiological and pupil diameter can be used for noninvasive real-time measurement of workload.
Application:
The methods presented in this article, with current technological capabilities, are better suited for workplaces where the person is seated, offering the possibility of being applied to pilots and air traffic controllers.
Animal-derived collagen may contain viruses, and its impurity can cause immunological reactions. Chitosan, always required a neutralization step in fabricating it into the biocompatible tissue ...engineering scaffolds. To avoid these risks and simplify the production process, a series of recombinant human collagen/carboxylated chitosan (RHC-CHI) based soft hydrogel scaffolds were prepared by crosslinking-induced gelation and then investigated their feasibilities for use as soft tissue engineering scaffolds. The gelation time was optimized by modulating the biopolymer concentration or reaction temperature. The hydrogel swelling, degradation rate, and mechanical properties were also investigated. The results showed that these parameters could be tuned by adjusting either the RHC-to-chitosan ratio or the total polymer concentration. The mechanical properties of the hydrogels were improved by adding chitosan, but excess chitosan reduced the hydrogel mechanical strength and accelerated the degradation speed. Cytotoxicity tests showed that all fabricated soft hydrogels were biocompatible and displayed no cytotoxicity. Cytocompatibility tests and qRT-PCR studies indicated that the hydrogel system promoted the adhesion and proliferation of NIH-3T3 cells, and cellular activities were directly up-regulated by RHC. Finally, our in vivo study proved these hydrogels were able to accelerate the cell infiltration and wound closure. These results show that the soft RHC-CHI hydrogels show promise in soft-tissue engineering.
•Developed Recombinant human collagen/chitosan soft hydrogels with tunable mechanical properties.•In vitro study proved the fibroblasts proliferation activities directly regulated by the fraction of recombinant human collagen.•In vivo study confirmed these hydrogels can accelerate the tissue regeneration.
Tissue engineering offers a promising alternative to the use of autografts in the treatment of ligament injuries. However, current approaches using only biodegradable materials have insufficient ...mechanical strength for load bearing applications. In this research, hybrid bio-artificial ligaments were fabricated using a combination of a titanium alloy spring and a fibrin gel/fibroblast construct. The ends of the ligament prosthesis were incorporated into brushite cement anchors to allow fusion with the host bone. Cell attachment to the titanium spring was examined using scanning electron microscopy and fluorescent staining of cells. The unreinforced constructs were observed to fail at the anchor-ligament junction, while the titanium spring reinforcement was found to assist in even transmission of the load to the ligament, and hence to provide a means of load sharing between the biological construct and the spring. As a result, the reinforced construct failed primarily in the soft tissue region. The good load distribution features from the mechanical data was attributed to the good cellular level adhesion to, and alignment along the coiling of, the length of the spring reinforcement. Incorporation of a biocompatible reinforcement in conjunction with a tissue engineered construct gave improved load distribution, reducing stress concentrations, and significantly increased the ultimate strength at failure. The results suggest that the hybrid approach used here shows promise in developing improved therapies for connective tissue injuries.
As an alternative biopolymer material without the risks of the use of animal-derived collagens in soft tissue engineering applications, recombinant human collagen polypeptide (RHC) was used to ...construct three-dimensional porous scaffolds. RHC and RHC-chitosan (RHC-CHI) porous scaffolds were fabricated using a freeze-drying method to create highly porous internal structures and then cross-linked with 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide (EDC). All scaffolds had interconnected porous structures with high porosity (90%), and pore size that ranged from 111 µm to 159 µm. The swelling ability and in vitro degradation of the prepared scaffolds were investigated. The mechanical properties could be tailored to meet the requirements of end-use application by adjusting the concentrations of the polymer or cross-linking agent, and the resulting mechanical strengths were comparable to those of biological soft tissues. The cytocompatibility of the fabricated porous scaffolds was investigated by seeding 3T3 fibroblasts into the porous structures, and then cell proliferation, distribution, morphology, and synthesis of extra cellular matrix-associated proteins were assessed. The results indicated that RHC-based porous scaffolds were non-cytotoxic and promoted the attachment and proliferation of the seeded cells. Finally, the in vivo study proved these porous scaffolds were able to accelerate the cell infiltration and collagen deposition that promoted the wound closure. Overall, the results indicate that RHC-based porous scaffolds show promise for use in soft tissue engineering due to their excellent in vitro cytocompatibility and adjustable mechanical properties.
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•Recombinant human collagen based porous scaffolds fabricated by freeze-drying.•Carbodiimide reinforces the tissue engineering porous scaffolds.•Mechanical strengths of scaffolds are comparable to some of native tissue.•Porous scaffolds promote the proliferation and migration of seeded fibroblasts.
Low moduli cell culture substrates can be used to apply dynamic mechanical strain to cells, by surface deformation. Understanding the surface interaction with cells is critical to improving cell ...adhesion and normal growth. A medical grade polyurethane (PU), Chronoflex AL 80A, was modified by oxygen plasma etching and characterised by X-ray photoelectron spectroscopy. Etching resulted in increased cross-linking at the isocyanate bond and formation of new oxygen moieties. The model, derived from patent data and XPS data of the unetched PU, indicated that the additional oxygen was likely to be hydroxyl and carbonyl groups. Etched membranes enhanced protein adhesion, resulting in full surface coverage compared to unetched PU. The etched PU supported cell adhesion and spreading, while the unetched PU was not conducive to monolayer formation.
Indoor rowing, which began as a means of keeping fit when conditions do not allow training on the water, has become a sport in its own right, and indoor rowers are found in gyms and fitness clubs ...worldwide and performed by many athletes for cross-training and conditioning. A mathematical model is presented and is used to analyze the dynamics of a rower in a single scull on the water and to compare these with the dynamics of the ergometer system. The results show that while the ergometer provides an acceptable simulation of the entire system dynamics, it cannot simulate the movement of the boat during the recovery, the sensitivity of the boat to movement of the body during the recovery when the blades are out of the water. The model shows that the hull speed of the boat, and hence the drag on the boat, is highest during the recovery, and hence underlines the importance of technique during the recovery to the overall speed of the boat on the water. It can be concluded that the ergometer is a useful training tool for rowers and other athletes, but it cannot improve poor technique or teach good technique.
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