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Liquid crystal microdroplets with readily adjustable optical properties have attracted considerable attention for building reconfigurable optofluidic microsystems for sensing, imaging, and light routing applications. In this quest, development of active optical microcavities serving as versatile integrated sources of coherent light and ultra-sensitive environmental sensors has played a prominent role. Here, we study transportable optofluidic microlasers reversibly tunable by an external electric field, which are based on fluorophore-doped emulsion droplets of radial nematic liquid crystals manipulated by optical tweezers in microfluidic chips with embedded liquid electrodes. Full transparency of the electrodes formed by a concentrated electrolyte solution allows for applying an electric field to the optically trapped droplets without undesired heating caused by light absorption. Taking advantage of independent, precise control over the electric and thermal stimulation of the lasing liquid crystal droplets, we characterize their spectral tuning response at various optical trapping powers and study their relaxation upon a sudden decrease in the trapping power. Finally, we demonstrate that sufficiently strong applied electric fields can induce fully reversible phase transitions in the trapped droplets even below the bulk melting temperature of the used liquid crystal. Our observations indicate viability of creating electrically tunable, optically transported microlasers that can be prepared on-demand and operated within microfluidic chips to implement integrated microphotonic or sensing systems.

We studied ranging and feeding behavior of Cypriot fruit bats during the summer and winter, which are critical periods with limited food supply and adverse conditions. Seasonal changes in ranging behavior were characterized by a steep increase in the size of core feeding areas and home ranges from summer to winter. Males and females did not differ in the size of summer and winter core areas and home ranges, but they differed in the distance they traveled to summer feeding sites. Summer food consisted of fruits of Ficus caricaand flowers of Agave americana.Winter food consisted of dates, fruits of Melia azedarach, Citrus reticulata, C. limon, Myrtus communis, and the flowers of Eucalyptusspp. Males and females differed as to the proportion of time they spent feeding on different food types, which may be explained by sexual differences related to food quality requirements. Summer foraging activity tended to be in areas with water bodies and larger fruit orchards. Winter foraging activity occurred more in areas with larger fruit orchards, a higher number of citrus plantations and date palms, typically located in built-up areas. The body condition of the bats was worse during the summer, which we assume was the result of their more limited diet during this period, making summer a more stressful period for them than winter. Active conservation management of Cypriot fruit bats should include the construction of artificial water sources in the vicinity of fruit orchards, but also controversial practices such as supporting the occurrence of particular nonnative plant species, thereby enhancing food availability in critical times of the year.

We present a tunable extended-cavity semiconductor laser, based on the Littman configuration, which has been frequency-stabilized to Doppler-free hyperfine transitions in I_2. The stability was measured compared with the reference He–Ne–I_2 laser system, whereas the semiconductor laser was locked on components of the P(33) 6—3 transition close enough to the reference R(127) 11—5 line to allow beat frequency counting. A relative stability of 4 × 10^-12 over a 100-s integration time was achieved. The laser configuration allowed mode-hop-free tuning over a range including the P(33) 6—3 transition and the group of strong overlapping transitions R(60) 8—4, R(125) 9—4, and P(54) 8—4 with higher signal-to-noise ratio than the P(33) 6—3 located approximately 13 GHz toward lower optical frequencies.

The local network of digital seismic stations WEBNET monitors the seismic activitv of practically the whole region of Western Bohemia/Vogtland swarms. The network consists of ten short-period stations and one very broadband station. The paper describes the configuration of the network, instrumental equipment and the basic parameters of the stations. The method of and formula for computing the local magnitudes from the WEBNET and KRASLICE seismograms are also given. Based on continuous WEBNET observations in the period 1995-1999, we were able to improve the model of temporal and spatial energy release in the region, the principal characteristics of which are summarised in the paper. Apart from direct P and S waves, the WEBNET seismograms also contain other significant P- and S-type waves, provisionally interpreted as reflected PxP, SxS and SxP waves. The fundamental characteristics of these waves are given in the paper, and tentative mechanisms of their origination are discussed. The large residua in the travel times of the P and S waves, and the discrepancies in the seismograms recorded at stations located east of the principal focal zone are pointed out.

We present the first results of a comparison of deep lithosphere structure of three Variscan massifs - the Armorican Massif, French Massif Central and Bohemian Massif, as revealed by recent tomographic studies of seismic anisotropy. The data originate from several field measurements made in temporary arrays of stations equipped with both short-period and broadband seismometers with digital recording. The study is based on teleseismic body waves and a joint inversion of anisotropic data (P-residual spheres, the fast shear-wave polarizations and split times) and demonstrates that the three Variscan massifs appear to consist of at least two parts with different orientation of large-scale fabric derived from seismic anisotropy. The boundaries of anisotropic lithospheric domains are related to prominent tectonic features recognised on the surface as sutures, shear zones or transfer fault zones, as well as grabens, thus indicating that some of them extend deep through the entire lithosphere.