Human social interaction is often intermittent. Two acquainted persons can have extended periods without social interaction punctuated by periods of repeated interaction. In this case, the repeated interaction can be characterized by a seed initiative by either of the persons and a number of follow-up interactions. The tendency to initiate social interaction plays an important role in the forma...

Drug use and problems change dramatically over time in ways that are often described as reflecting an “epidemic cycle”. We use simulation of a model of drug epidemics to investigate how the relative effectiveness of different types of prevention varies over the course of such an epidemic. Specifically we use the so-called LHY model (see Behrens et al., 2000b) which includes both “contagious” sp...

In a blended learning environment, paper-based evaluation has still been the preferred assessment method of student’s learning because of the convenience it offers. In programming learning, several automatic programming evaluation tools have been developed. However, they are less focused on grading paper-based programming problems. In this paper, we discuss a homegrown educational technology ca...

Direct numerical simulations, (DNS), are used to simulate the decay of an isotopic, turbulent, chemically-reacting flow at high temperatures. The independent parameters that govern the physical process are introduced. The different effects from each of the parameters in the flow are explained by using the results from the DNS. It is found that there is a feedback mechanism between the chemical ...

The consensus view is that economists should observe consumer choices and abstain from investigating the psychological and physiological causes of wants, or the mechanisms governing the formation of preferences. This may be a correct procedure as far as ordinary functional goods are concerned. Problems tend to arise with creative goods (e.g. cultural goods) that share two common features, namel...

Feedback is used primarily for reducing the effects of the plant uncertainty on the performance of control systems, and as such understanding the following questions is of fundamental importance: How much uncertainty can be dealt with by feedback? What are the limitations of feedback? How does the feedback performance depend quantitatively on the system uncertainty? How can the capability of fe...

has the desired specifications. The main role of state feedback control is to stabilize a given system so that all closed-loop eigenvalues are placed in the left half of the complex plane. The following theorem gives a condition under which is possible to place system poles in the desired locations. Theorem 8.1 Assuming that the pair is controllable, there exists a feedback matrix such that the...

This paper presents two new corpus-based studies of feedback in the domain of teaching Spanish as a foreign language, concentrating on the type and frequency of different feedback moves, as well as what happens in the moves that follow the feedback. In particular, as well as looking at positive feedback, it concentrates on two general kinds of negative feedback strategies: (1) Giving-Answer Str...

[1] In this study, scale interaction between synoptic eddies and low-frequency flow is investigated. The synoptic eddy feedback is a key process in sustaining the low-frequency flow. We show clear evidence using NCEP reanalysis data that there is a general underlying rule—the ‘‘left-hand rule’’, governing the synoptic eddy feedback onto low-frequency flow. This rule states that eddy-vorticity f...

In a commentary in Nature, Rodney Brooks1 proposed that something is missing from our models of living and behaving systems. I would like to suggest that it is not something undiscovered that is missing, but something old that has been passed over without sufficient examination. What is missing from most “modern” conceptions of behavioral mechanisms may be a sufficient understanding of a remark...