Developing a Model with Ergonomic Aspects Using Endurance Time and Rest Allowance for Supporting the Optimization of Production Line Material Supply: A Case of Single-Operator Multi-Materials

Various studies on the issues regarding economic and environmental sustainability in inventory management have been investigated by many researchers in recent years. However, the integration of ergonomics as an aspect of social sustainability in an inventory model is still scarce. This paper presents an extension of ergonomic inventory modeling with a new mathematical model which integrates relaxation allowance and endurance time to the ergonomic inventory model. The rest allowance is determined by endurance time, contraction time, and relative force based on several items such as weight, and it helps to prevent ergonomic risks and fatigue of the back muscles. The model has been analyzed in a numerical work based on our specific simulator and parameteric analysis to present validness in different scenarios. Consequently, our results show that optimization with ergonomics in production line material supply provides notable advantages as it increases overall productivity.

A wrinkle in and of time: Contraction of felt duration with a single perceptual switch

The way we represent and perceive time has crucial implications for studying temporality in conscious experience. Contrasting positions posit that temporal information is separately abstracted out like any other perceptual property through specialized mechanisms or that time is represented through the temporality of experiences themselves. To add to this debate, we investigate alterations in felt time in conditions where only conscious visual experience is altered through perceptual switches while a bistable figure remains physically unchanged. We predicted that if perceived time is a function of temporally evolving conscious content, then a break in it (here via a perceptual switch) would also lead to a break in felt time. In three experiments, we showed participants a Necker cube which was manipulated to induce a perceptual switch (experiment 1(a) and 1(b)) or left to switch on its own (experiment 2). We asked participants to report both perceptual switches and felt durations (experiment 1(a) and 2) or only estimate time (experiment 1(b). Over these three experiments, we find evidence of contraction of felt time in trials with a perceptual switch, consistent with the idea that perceived time is a function of temporally evolving conscious experience. Additionally, we present a phenomenological demonstration to support our empirical data. Overall, the study provides evidence for temporal mirroring and isomorphism in visual experience, arguing for a link between the timing of experience and time perception.

Fluctuation Scaling of Neuronal Firing and Bursting in Spontaneously Active Brain Circuits

We employed high-density microelectrode arrays to investigate spontaneous firing patterns of neurons in brain circuits of the primary somatosensory cortex (S1) in mice. We recorded from over 150 neurons for 10[Formula: see text]min in each of eight different experiments, identified their location in S1, sorted their action potentials (spikes), and computed their power spectra and inter-spike interval (ISI) statistics. Of all persistently active neurons, 92% fired with a single dominant frequency — regularly firing neurons (RNs) — from 1 to 8[Formula: see text]Hz while 8% fired in burst with two dominant frequencies — bursting neurons (BNs) — corresponding to the inter-burst (2–6[Formula: see text]Hz) and intra-burst intervals (20–160[Formula: see text]Hz). RNs were predominantly located in layers 2/3 and 5/6 while BNs localized to layers 4 and 5. Across neurons, the standard deviation of ISI was a power law of its mean, a property known as fluctuation scaling, with a power law exponent of 1 for RNs and 1.25 for BNs. The power law implies that firing and bursting patterns are scale invariant: the firing pattern of a given RN or BN resembles that of another RN or BN, respectively, after a time contraction or dilation. An explanation for this scale invariance is discussed in the context of previous computational studies as well as its potential role in information processing.