No abstract

Air quality measurement is a topic of a great interest for any country due to health and environmental reasons. Tis issue is more critical in low-incomes countries since the air quality is generally worse than in developed countries and the governments give fewer budget to lead environmental policy and research. This explains the increasing demand for low-cost dust optical sensors like the Shinyei PPD24NS during the last years. However, those sensors present mixed results in terms of precision and repeatability, especially in case of new applications like the ones in moving context. Moreover, few or confuse information exists on those sensors functioning and conditions of use and the manufacturer does not provide any comprehensive guideline. The present article aims at filling this gap, providing a real study of the internal sensor operating. This includes: a detailed, theoretical and practical, analysis of the electric diagram, a characterization of the airflow through the optical chamber, an output behavior analysis based on particulate matter concentration and some algorithmic issues guideline. The article ends by providing useful tips and recommendations as well as some tracks to improve its precision for new applications.

Background Inhibitory control, a key modulatory component of cognition guiding strategy and behaviour, can be affected by diverse contingencies. We explore here the effect of expectation of reward over behavioural adjustment in a Stop Signal Task modulated by reward. We hypothesize that cognitive control is modulated by different expectation of the reward. Methods Participants were allocated to two groups differing in their degree of knowledge in what to expect from rewards. Expected Specific Reward participants ( N = 21) were informed of the different monetary feedbacks they would receive after each successful inhibition. Unexpected Reward participants ( N = 24) were only told that they would receive monetary reward after correct inhibitory trials, but not the amounts or differences. Results Our results confirmed previous observations demonstrating a “kick-start effect” where a high reward feedback at the beginning of the task increases response inhibition. The Expected Specific Reward condition seems also to improve inhibitory control -as measured by the stop signal reaction time (SSRT)-, compared to the Unexpected Reward group. Conclusions Knowledge of reward magnitudes seems to play a role in cognitive control irrespective of feedback magnitude. The manipulation of reward expectation appears to trigger different strategies for cognitive control, inducing a bottom-up effect of external cues, or a top-down effect given by the anticipation of incoming rewards. This is an early exploration to unearth possible higher order modulators - expectation and motivation- of cognitive control. This approach aims to gain insight into diverse psychopathological conditions related to impulsivity and altered reward systems such as Attention Deficit Hyperactive Disorder (ADHD), personality disorders, substance abuse, pathological gambling and cognitive aspects of Parkinson Disease. Electronic supplementary material The online version of this article (10.1186/s40359-019-0332-x) contains supplementary material, which is available to authorized users.

International audienc

Engineering students in control courses have been observed to lack an understanding of equilibrium and stability, both of which are crucial concepts in this discipline. The introduction of these concepts is generally based on the study of classical examples from Newtonian mechanics supplemented with a control system. Equilibrium and stability are approached in different ways at the various stages of a typical engineering syllabus: at the beginning, they are mostly dealt with a static point of view, for example in mechanics, and are subsequently handled through dynamic analysis in control courses. In general, there is a little clarification of the differences between these concepts or the ways in which they are linked. We believe that this leads to much confusion and incomprehension among engineering students. Several studies have shown that students encounter difficulties when presented with simple familiar or academic static equilibrium cases in mechanics. Our study investigates students' conceptions and misconceptions about equilibrium and stability through a series of questions about several innovative nonstatic situations. It reveals that the understanding of these notions is shaken when the systems being studied are placed in inertial or non-inertial moving reference frames. The students in our study were particularly uncertain about the existence of unstable equilibrium positions and had difficulty in differentiating between the two concepts. The results suggest that students use a velocity-based approach to explain such situations. A poor grasp of the above fundamental concepts may result from previous learning experiences. More specifically, certain difficulties seem to be directly linked to a lack of understanding of these concepts, while others are related to misconceptions arising from everyday experiences and the inappropriate use of physical examples in primary school.

Deteriorating air quality is of great concern around the world. Recently, citizen scientists, researchers, and many others have used low-cost devices such as the Shinyei PPD42NS dust sensor to measure particulate matter pollution in both developed and under-developed countries. However, few articles exist specifically on the features and performance of these sensors. Some have shown mixed results in terms of precision, accuracy, and repeatability, especially for portable applications. Frequently, users assemble the electronics and the sensors applying simple guidelines, using electric schematics, and coding extraneous algorithms to get questionable data. There is a need to better understand how it works exactly, its limitations and the effect of the program used to interpret the outputs of this sensor. This article provides a short electronic analysis of the Shinyei PPD42NS dust sensor and shows that the internal sensor electronic design (filters and detection stage) as well as the used data processing algorithm, limit its precision and accuracy by generating nonlinearities and biases. These issues avoid some applications like moving ones and imply that the algorithm used to process the sensor signals must be clearly presented in future articles.

No abstract

No abstract