Active region

This work presents recent results on high-power, high-effi- ciency two-dimensional vertical-cavity surface-emitting laser (VCSEL) arrays emitting around 980 nm. More than 230 W of continuous-wave (CW) power is demonstrated from a ~5 mm x 5 mm chip. In quasi-CW mode, smaller chips exhibit 100 W output power, corresponding to more than 3.5 kW/cm 2 of power density. We show that

We report the results of a multi-instrument, multi-technique, coordinated study of the solar eruptive event of 13 May 2005. We discuss the resultant Earth-directed (halo) coronal mass ejection (CME), and the effects on the terrestrial space environment and upper Earth atmosphere. The interplanetary CME (ICME) impacted the Earth's magnetosphere and caused the most-intense geomagnetic storm of 2005 with a Disturbed Storm Time ( Dst) index reaching -263 nT at its peak. The terrestrial environment responded to the storm on a global scale. We have combined observations and measurements from coronal and interplanetary remote-sensing instruments, interplanetary and near-Earth in-situ measurements, remote-sensing observations and in-situ measurements of the terrestrial magnetosphere and ionosphere, along with coronal and heliospheric modelling. These analyses are used to trace the origin, development, propagation, terrestrial impact, and subsequent consequences of this event to obtain t...

Summary form only given. Aluminum-free laser diodes emitting at wavelengths from 800 to 1100 nm, prepared by metal-organic chemical vapor deposition, gas-source molecular beam epitaxy, and all-solid-source molecular beam epitaxy (SS-MBE), are a debated issue. The main question is the lifetime performance that is not yet explored well enough, owing to the lack of availability of these lasers. The potential

The Algerian margin is a seismically active region, where during the last century, several large magnitude earthquakes took place. This study combines geotechnical and sedimentological data with numerical modelling to quantitatively assess the present-day slope stability of the Algerian margin. Geotechnical laboratory tests, such as cyclic triaxial tests, oedometric tests and vane shear tests were carried out on sediment cores collected on the study area. The liquefaction potential of a sediment column located about 30 km from the Boumerdès earthquake epicentre of 21st May 2003 was evaluated theoretically for an earthquake of M w = 6.8. We show that thin sand and silt beds such as those described on recovered sediment cores are the main cause of sediment deformation and liquefaction during earthquakes. Numerical calculations showed that the slope failure may occur during an earthquake characterised by a PGA in excess of 0.1g, and also that, under a PGA of 0.2g liquefaction could be ...

The photometric distortion waves in the light curves of the short-period RS CVn system BH Vir by a dark, circular spot model for the active regions on the primary star is parameterized. Recent observations and archival sources are used to infer the positions and areas of the active regions. For light curves with simultaneous B and R or V and

ABSTRACT An optically pumped ZnO distributed feedback laser operating at 383 nm has been designed, fabricated and characterized. Single mode operation was observed for a wide temperature range between 10 and 270 K. In order to avoid technologically difficult etching of ZnO, a 3rd order diffraction grating was dry-etched into an additional 120 nm-thick Si3N4 layer deposited on the ZnO active region. The spectral linewidth of the laser emission was 0.4 nm, whereas an optical pump threshold intensity of 0.12 MW/cm2 and a peak output power of 14 mW were seen. The temperature tuning coefficient of the ZnO refractive index was determined from wavelength vs. temperature measurements; a value of 9 x 10-5 K-1 was found, in good agreement with literature values.

This paper describes the generation–recombination processes taking place in the active region of p–i–n structure with embedded quantum dots (QDs). The photocurrent is found by solving self-consistently the continuity equation in inter-layers taking into account the existence of QDs through the effective surface recombination rate. It is shown that there is an optimal number of stacked QD layers to be

Active regions on the solar surface are known to possess magnetic helicity, which is predominantly negative in the northern hemisphere and positive in the southern hemisphere. Choudhuri et al. [Choudhuri, A.R. On the connection between mean field dynamo theory and flux tubes. Solar Phys. 215, 31–55, 2003] proposed that the magnetic helicity arises due to the wrapping up of the poloidal field of the convection zone around rising flux tubes which form active regions. Choudhuri [Choudhuri, A.R., Chatterjee, P., Nandy, D. Helicity of solar active regions from a dynamo model. ApJ 615, L57–L60, 2004] used this idea to calculate magnetic helicity from their solar dynamo model. Apart from getting broad agreements with observational data, they also predict that the hemispheric helicity rule may be violated at the beginning of a solar cycle. Chatterjee et al. [Chatterjee, P., Choudhuri, A.R., Petrovay, K. Development of twist in an emerging magnetic flux tube by poloidal field accretion. A&A 449, 781–789, 2006] study the penetration of the wrapped poloidal field into the rising flux tube due to turbulent diffusion using a simple 1-d model. They find that the extent of penetration of the wrapped field will depend on how weak the magnetic field inside the rising flux tube becomes before its emergence. They conclude that more detailed observational data will throw light on the physical conditions of flux tubes just before their emergence to the photosphere.

The act of tasting is the product of inseparable integrative behavior consisting of multi-sensory processing and orolingual motor coordination. Often tasting-induced brain activity is looked at in a reductionist manner as a set of isolated components. However, brain activity as a whole during tasting may not simply be the sum of isolated brain responses; therefore, attempting to look at the