Neural control on multiple time scales: Insights from human stick balancing

The time-delayed feedback control mechanisms of the nervous system are continuously subjected to the effects of uncontrolled random perturbations (herein referred to as noise). In this setting the statistical properties of the fluctuations in the controlled variable(s) can provide non-invasive insights into the nature of the underlying control mechanisms. We illustrate this concept through a study of stick balancing at the fingertip using high speed motion capture techniques. Experimental observations together with numerical studies of a stochastic delay differential equation demonstrate that on time scales short compared to the neural time delay (“fast control”), parametric noise provides a non-predictive mechanism that transiently stabilizes the upright position of the balanced stick. Moreover, numerical simulations of a delayed random walker with a repulsive origin indicate that even an unstable fixed point can be transiently stabilized by the interplay between noise and time delay. In contrast, on time scales comparable to the neural time delay (“slow control”), feedback and feedforward control mechanisms become more important. The relative contribution of the fast and slow control mechanisms to stick balancing is dynamic and, for example, depends on the context in which stick balancing is performed and the expertise of the balancer

Collisional and Radiative Processes in Optically Thin Plasmas

Most of our knowledge of the physical processes in distant plasmas is obtained through measurement of the radiation they produce. Here we provide an overview of the main collisional and radiative processes and examples of diagnostics relevant to the microphysical processes in the plasma. Many analyses assume a time-steady plasma with ion populations in equilibrium with the local temperature and Maxwellian distributions of particle velocities, but these assumptions are easily violated in many cases. We consider these departures from equilibrium and possible diagnostics in detail

Cold War : a Transnational Approach to a Global Heritage

Although within living memory, many countries now consider their surviving Cold War architecture as part of their heritage. It can even be a priority for heritage managers given that significant buildings are often suitable for reuse while extensive ‘brownfield’ sites such as airfields can be used for large-scale redevelopment. In a number of countries whose work we refer to here (notably the United Kingdom and elsewhere in Europe), agencies responsible for managing their country’s heritage have approached this priority by creating national inventories of sites and buildings with a view to taking informed decisions on their future. This paper presents the argument that the wider international context of the Cold War provides a more appropriate (or additional, higher-level) framework for such decision making. Such a ‘transnational’ approach would allow the comparison of similar (e.g. European) sites not merely within national borders but across the full extent of their western NATO1 deployment in Europe and North America. Taking this approach would also allow comparison with related sites in countries that formed part of the eastern-bloc Warsaw Pact.2 After outlining some examples of how national agencies have approached their Cold War heritage, this paper presents the four stages of this transnational approach making provision for an improved understanding and management of Cold War heritage sites wherever they occur. With a specific focus on the direct comparison between England and Russia, and also referring to sites surviving elsewhere within the former NATO and Warsaw Pact regions, as well as the United States, we argue that this four-stage approach: provides new understandings of a complex archaeological and architectural record; gives fresh perspectives on significance; and (importantly in a time of geopolitical instability) does so in a spirit of cooperation and friendship

Analisis Pola Pengambilan Mata Kuliah dan Kinerja Mahasiswa Tiap Angkatan dengan Menggunakan Teknik Process Mining

Institut Teknologi Sepuluh Nopember merupakan salah satu perguruan teknik negeri yang telah menerapkan sistem informasi akademik untuk mendukung proses perkuliahan mahasiswa. Dalam menjalankan proses perkuliahan tentunya telah ditetapkan kurikulum yang bersifat standar. Namun pada kenyataannya tidak jarang ada perbedaan antara proses perkuliahan yang didefinisikan dalam kurikulum dengan proses perkuliahan yang dijalankan mahasiswa. Hal ini dapat menyebabkan proses perkuliahan mahasiswa terhambat dan menyebabkan mahasiswa lulus dengan tidak tepat waktu ataupun dengan IPK yang kurang baik. Pemodelan proses perkuliahan dilakukan per-angkatan mahasiswa dengan menggunakan teknik process mining. Teknik process mining dipilih karena dengan menggunakan metode ini dapat diketahui pola pengambilan matakuliah suatu angkatan dari pemodelan proses yang memanfaatkan event log yang sudah didapatkan dari sistem informasi akademik ITS. Hasil dari tugas akhir ini adalah model petri net dari proses pengambilan mata kuliah mahasiswa tiap angkatan dari awal masuk hingga menyelesaikan perkuliahan. Analisis yang didapatkan yakni yang pertama adalah banyaknya variasi alur pengambilan mata kuliah untuk setiap mahasiswa serta kinerja mahasiswa berdasarkan IPK dan lama studi, kedua adalah mengenai turunnya kinerja angkatan yang mengalami ekivalensi pada kurikulum 2004 ke 2009 namun tidak berlaku pada angkatan yang mengalami ekivalensi pada kurikulum 2009 ke 2014

Mesures de la biomasse racinaire d'une culture de ble

Document interne *INRA, Station de Bioclimatologie Montfavet (FRA) Diffusion du document : INRA, Station de Bioclimatologie Montfavet (FRA)National audienc

Estimation de l'energie photosynthetiquement active absorbee par une culture de ble a partir de donnees radiometriques

Document interne *INRA, Station de Bioclimatologie Montfavet (FRA) Diffusion du document : INRA, Station de Bioclimatologie Montfavet (FRA)National audienc

Estimation de l'energie photosynthetiquement active absorbee par une culture de ble a partir de donnees radiometriques

Document interne *INRA, Station de Bioclimatologie Montfavet (FRA) Diffusion du document : INRA, Station de Bioclimatologie Montfavet (FRA)National audienc