Search results for "HZ"
showing 10 items of 47 documents
Automotive Radar in a UAV to Assess Earth Surface Processes and Land Responses
2020
The use of unmanned aerial vehicles (UAVs) in earth science research has drastically increased during the last decade. The reason being innumerable advantages to detecting and monitoring various environmental processes before and after certain events such as rain, wind, flood, etc. or to assess the current status of specific landforms such as gullies, rills, or ravines. The UAV equipped sensors are a key part to success. Besides commonly used sensors such as cameras, radar sensors are another possibility. They are less known for this application, but already well established in research. A vast number of research projects use professional radars, but they are expensive and difficult to hand…
First M87 Event Horizon Telescope Results. I. the Shadow of the Supermassive Black Hole
2019
When surrounded by a transparent emission region, black holes are expected to reveal a dark shadow caused by gravitational light bending and photon capture at the event horizon. To image and study this phenomenon, we have assembled the Event Horizon Telescope, a global very long baseline interferometry array observing at a wavelength of 1.3 mm. This allows us to reconstruct event-horizon-scale images of the supermassive black hole candidate in the center of the giant elliptical galaxy M87. We have resolved the central compact radio source as an asymmetric bright emission ring with a diameter of 42 ± 3 μas, which is circular and encompasses a central depression in brightness with a flux rati…
Two-qubit entanglement dynamics for two different non-Markovian environments
2009
We study the time behavior of entanglement between two noninteracting qubits each immersed in its own environment for two different non-Markovian conditions: a high-$Q$ cavity slightly off-resonant with the qubit transition frequency and a nonperfect photonic band-gap, respectively. We find that revivals and retardation of entanglement loss may occur by adjusting the cavity-qubit detuning, in the first case, while partial entanglement trapping occurs in non-ideal photonic-band gap.
Modulatory effects of 1 Hz rTMS over the cerebellum on motor cortex excitability
2005
Clinical observations and data from animal experiments point to a physiological facilitatory influence of the deep cerebellar structures on the motor system through the cerebello-thalamo-cortical pathways. The aim of the present study was to explore the long-term effects of low-frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) over the cerebellum on short intracortical inhibition (SICI) and facilitation (ICF) of the motor cortex in normal subjects. Eight healthy subjects (mean age 26.9 +/- 3.1) underwent 1 Hz frequency rTMS delivered on the right cerebellar hemisphere. Before and after cerebellar rTMS, SICI and ICF were assessed in the motor cortex contralateral to the st…
Decoding vibrational states of Concanavalin A amyloid fibrils.
2015
International audience; Amyloid and amyloid-like fibrils are a general class of protein aggregates and represent a central topic in life sciences for their involvement in several neurodegenerative disorders and their unique mechanical and supramolecular morphological properties. Both their biological role and their physical properties, including their high mechanical stability and thermodynamic inertia, are related to the structural arrangement of proteins in the aggregates at molecular level. Significant variations may exist in the supramolecular organization of the commonly termed cross-β structure that constitutes the amyloid core. In this context, a fine knowledge of the structural deta…
Antennas for the detection of radio emission pulses from cosmic-ray induced air showers at the Pierre Auger Observatory.
2012
The Pierre Auger Observatory is exploring the potential of the radio detection technique to study extensive air showers induced by ultra-high energy cosmic rays. The Auger Engineering Radio Array (AERA) addresses both technological and scientific aspects of the radio technique. A first phase of AERA has been operating since September 2010 with detector stations observing radio signals at frequencies between 30 and 80 MHz. In this paper we present comparative studies to identify and optimize the antenna design for the final configuration of AERA consisting of 160 individual radio detector stations. The transient nature of the air shower signal requires a detailed description of the antenna s…
Wideband THz time domain spectroscopy based on optical rectification and electro-optic sampling
2013
We present an analytical model describing the full electromagnetic propagation in a THz time-domain spectroscopy (THz-TDS) system, from the THz pulses via Optical Rectification to the detection via Electro Optic-Sampling. While several investigations deal singularly with the many elements that constitute a THz-TDS, in our work we pay particular attention to the modelling of the time-frequency behaviour of all the stages which compose the experimental set-up. Therefore, our model considers the following main aspects: (i) pump beam focusing into the generation crystal; (ii) phase-matching inside both the generation and detection crystals; (iii) chromatic dispersion and absorption inside the c…
Monte Carlo simulation of high‐order harmonics generation in bulk semiconductors and submicron structures
2004
To qualify the feasibility of standard semiconductor materials and Schottky‐barrier diodes (SBDs) for THz high‐order harmonic generation and extraction, the harmonic intensity, intrinsic noise and signal‐to‐noise ratio are calculated by the Monte Carlo method when a periodic high‐frequency large‐amplitude external signal is applied to a semiconductor device. Due to very high signal‐to‐noise ratio heavily doped GaAs SBDs are found to exhibit conditions for frequency mixing and harmonic extraction that are definitively superior to those of bulk materials. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Combined Effects of 50 Hz Electromagnetic Field and SiO2 Nanoparticles on Oxidative Stress in Plant’s Gametic Cells / Zemfrekvences (50 Hz) Elekromag…
2015
Abstract The paper presents the results of combined effects of an extremely low frequency electromagnetic field (50 Hz) (ELF EMF) and SiO2 nanoparticles on fluorescence of plant gametic cells (immature microspores). The data were recorded by a BD FACSJazz® cell sorter after cell irradiation by blue laser (488 nm). A significant difference of fluorescence was observed between gametic cells after 1 hour incubation in suspension of SiO2 nanoparticles and the control gametic cells. It was observed that fluorescence intensity of gametic cell was higher with ELF EMF treatment in comparison to control cells, but it was statistically significant only for cells treated with electromagnetic radiation…
CESAR: Cryogenic Electronics for Space Applications
2013
Ultra-low temperature sensors provide unprecedented performances in X-ray and far infrared astronomy by taking advantage of physical properties of matter close to absolute zero. CESAR is an FP7 funded project started in December 2010, that gathers six European laboratories around the development of high performances cryogenic electronics. The goal of the project is to provide far-IR, X-ray and magnetic sensors with signal-processing capabilities at the heart of the detectors. We present the major steps that constitute the CESAR work, and the main results achieved so far.