Konsepsi Mahasiswa Tentang Cepat Rambat Gelombang Pada Permukaan Air

Salah satu fenomena fisika yang paling dekat dengan kita adalah gelombang mekanis seperti gelombang pada permukaan air. Parameter-parameter penting seperti kecepatan rambat, panjang gelombang, frekuensi, amplitudo, dan media perambatan sering dikaitkan berdasarkan konsepsi sederhana sehingga berpotensi terjadinya miskonsepsi. Penelitian ini bertujuan untuk mengetahui konsepsi mahasiswa tentang cepat rambat gelombang pada permukaan air. Sebanyak 53 mahasiswa tahun pertama pada program studi Pendidikan Matematika dan Pendidikan Fisika yang telah mengikuti mata kuliah fisika dasar dijadikan sampel uji tes diagnostik. Ditemukan bahwa lebih dari 80% sampel secara konsisten mengalami miskonsepsi tentang kecepatan rambat gelombang

DASA:an open-source design, analysis and simulation framework for automotive image-based control systems

Image-Based Control (IBC) systems are a class of data-intensive feedback control systems whose feedback is provided by image-based sensing using a camera. IBC has become popular with the advent of efficient image processing systems and low-cost CMOS cameras with high resolution. The combination of the camera and image processing (sensing) gives necessary information on parameters such as relative position, geometry, relative distance, depth perception and tracking of the object-of-interest. This enables the effective use of low-cost camera sensors to enable new functionality or replace expensive sensors in cost-sensitive industries like automotive.The state-of-the-art design, analysis, and simulation of IBC assumes that the sensing algorithm is executing correctly with an assumed or estimated worst-case delay. The sensing algorithm is simulated and validated using static pre-captured image streams and is normally decoupled from the control algorithm. However, in reality, the camera is fixed to the vehicle body and any steering change would affect the region captured by the image. This dynamism cannot be captured in a static image stream and a dynamic image stream that considers the change in vehicle dynamics due to IBC actuation is needed.We present an open-source design, analysis, and simulation framework for automotive IBC systems that can consider the change in vehicle dynamics in real-time and produces real-time dynamic image stream as per the control algorithm. Our framework models the 3D environment in 3ds Max, simulates the vehicle dynamics, camera position, environment and traffic in V-REP and computes the control output in Matlab. Our framework runs Matlab as a server and V-REP as a client in synchronous mode. We show the effectiveness of our framework using a vision-based lateral control system.<br/

‘Instead of fetching flowers, the youths brought in flakes of snow’: exploring extreme weather history through English parish registers

Parish registers provide organized, dated and located population data and as such, are routinely among the most frequently consulted documents within the holdings of county record offices and archives. Throughout history, extreme weather has had significant impacts on the church, its congregation, and local landscape. It is for these reasons that extreme weather events have been deemed worthy of official note by authors of many registers. Although isolated entries have been used as supporting evidence for the occurrence of a number of historic extreme weather events, the information that parish registers contain relating to weather history has not been studied in its own right. Parish register narratives add new events to existing chronologies of extreme weather events and contribute to our understanding of their impacts at the local level. As public and well used documents they also function to keep the memory of particular events alive. The examples in this paper cover a wide range of weather types, places, and time periods, also enabling recording practice to be explored. Finally, as the number of digitized registers increases, we highlight the risks of weather narratives being obscured, and reflect on how the weather history contained within might be systematically captured

The early phase of a bacterial insertion sequence infection

Bacterial insertion sequences are the simplest form of autonomous mobile DNA. It is unknown whether they need to have beneficial effects to infect and persist in bacterial populations, or whether horizontal gene transfer suffices for their persistence. We address this question by using branching process models to investigate the critical, early phase of an insertion sequence infection. We find that the probability of a successful infection is low and depends linearly on the difference between the rate of horizontal gene transfer and the fitness cost of the insertion sequences. Our models show that the median time to extinction of an insertion sequence that dies out is very short, while the median time for a successful infection to reach a modest population size is very long. We conclude that horizontal gene transfer is strong enough to allow the persistence of insertion sequences, although infection is an erratic and slow process

How Subtle Changes Can Make a Difference – Reproducibility in Complex Supramolecular Systems

The desire to construct complex molecular systems is driven by the need for technological (r)evolution and our intrinsic curiosity to comprehend the origin of life. Supramolecular chemists tackle this challenge by combining covalent and noncovalent reactions leading to multicomponent systems with emerging complexity. However, this synthetic strategy often coincides with difficult preparation protocols and a narrow window of suitable conditions. Here, we report on unsuspected observations of our group that highlight the impact of subtle “irregularities” on supramolecular systems. Based on the effects of pathway complexity, minute amounts of water in organic solvents or small impurities in the supramolecular building block, we discuss potential pitfalls in the study of complex systems. This article is intended to draw attention to often overlooked details and to initiate an open discussion on the importance of reporting experimental details to increase reproducibility in supramolecular chemistry