The SGR 1806-20 magnetar signature on the Earth's magnetic field

SGRs denote ``soft $\gamma$-ray repeaters'', a small class of slowly spinning neutron stars with strong magnetic fields. On 27 December 2004, a giant flare was detected from magnetar SGR 1806-20. The initial spike was followed by a hard-X-ray tail persisting for 380 s with a modulation period of 7.56 s. This event has received considerable attention, particularly in the astrophysics area. Its relevance to the geophysics community lies in the importance of investigating the effects of such an event on the near-earth electromagnetic environment. However, the signature of a magnetar flare on the geomagnetic field has not previously been investigated. Here, by applying wavelet analysis to the high-resolution magnetic data provided by the CHAMP satellite, a modulated signal with a period of 7.5 s over the duration of the giant flare appears in the observed data. Moreover, this event was detected by the energetic ion counters onboard the DEMETER satellite.Comment: Science Editors' Choice: http://www.sciencemag.org/content/vol314/issue5798/twil.dt

ヘテロジニアス光ネットワークの制御及び設計の研究

早大学位記番号:新8298早稲田大

Social Housing as a State-Funded Mega Project: A Case Study From Saudi Arabia

There are many kinds of war. They span from typical military conflicts to socially and politically charged environments, from fiscal colonization to ghostly wars about information and the internet. But what about the fear of a possible war? Could housing initiatives be connected to that? What kind of design methods and standards as well as processes would that specific case entail? What other factors would add pressure to studying and implementing housing projects in this context? What could be the possible measure of such projects’ eventual assessment? This paper is based on the assumption that fear of a spreading of the Arab Spring in the Saudi Kingdom triggered a massive state-funded housing project. The ambitious case of Saudi Arabia’s Ministry of Housing (MoH) will be discussed and gradually unfolded within its social, cultural, economic, and technical-design conditions. The project’s development is discussed both before its launch-conceptualization and throughout its implementation. The original insight given stems from the authors’ participation as lead urban planners in one of the major companies awarded the project

Statistical Mechanics and Information-Theoretic Perspectives on Complexity in the Earth System

Peer reviewedPublisher PD

Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagetic anomalies prior to the L'Aquila earthquake as pre-seismic ones. Part I

Ultra low frequency, kHz and MHz electromagnetic anomalies were recorded prior to the L'Aquila catastrophic earthquake that occurred on April 6, 2009. The main aims of this contribution are: (i) To suggest a procedure for the designation of detected EM anomalies as seismogenic ones. We do not expect to be possible to provide a succinct and solid definition of a pre-seismic EM emission. Instead, we attempt, through a multidisciplinary analysis, to provide elements of a definition. (ii) To link the detected MHz and kHz EM anomalies with equivalent last stages of the L'Aquila earthquake preparation process. (iii) To put forward physically meaningful arguments to support a way of quantifying the time to global failure and the identification of distinguishing features beyond which the evolution towards global failure becomes irreversible. The whole effort is unfolded in two consecutive parts. We clarify we try to specify not only whether or not a single EM anomaly is pre-seismic in itself, but mainly whether a combination of kHz, MHz, and ULF EM anomalies can be characterized as pre-seismic one