Molecular systematics of swifts of the genus Chaetura (Aves: Apodiformes: Apodidae)

Phylogenetic relationships among swifts of the morphologically conservative genus Chaetura were studied using mitochondrial and nuclear DNA sequences. Taxon sampling included all species and 21 of 30 taxa (species and subspecies) within Chaetura. Our results indicate that Chaetura is monophyletic and support the division of the genus into the two subgenera previously identified using plumage characters. However, our genetic data, when considered in combination with phenotypic data, appear to be at odds with the current classification of some species of Chaetura. We recommend that C. viridipennis, currently generally treated as specifically distinct from C. chapmani, be returned to its former status as C. chapmani viridipennis, and that C. andrei, now generally regarded as synonymous with C. vauxi aphanes, again be recognized as a valid species. Widespread Neotropical species C. spinicaudus is paraphyletic with respect to more range-restricted species C. fumosa, C. egregia, and C. martinica. Geographically structured genetic variation within some other species of Chaetura, especially notable in C. cinereiventris, suggests that future study may lead to recognition of additional species in this genus. Biogeographic analysis indicated that Chaetura originated in South America and identified several dispersal events to Middle and North America following the formation of the Isthmus of Panama

Millisecond optical phase modulation using multipass configurations with liquid-crystal devices

We present two configurations for analog 0 to 2π optical phase modulation using liquid crystals (LCs), each of which achieve switching times that are 1 ms or less. One configuration is based on the switching behavior of a so-called nematic pi cell, and the other is based on the flexoelectro-optic effect in chiral nematic LCs when operated in the uniform lying helix geometry. Both configurations exploit a multipass optical arrangement to enhance the available optical phase range, while maintaining a fast switching speed. Moreover, these devices can be operated at or close to room temperature. Experimental data are found to be in good agreement with results predicted from theory for these multipass phase-modulation configurations

Carotenoid-based skin ornaments reflect foraging propensity in a seabird, Sula leucogaster

Carotenoid-based ornaments are common signalling features in animals. It has long been proposed that such ornaments communicate information about foraging abilities to potential mates. However, evidence linking foraging with ornamentation is largely missing from unmanipulated, free-ranging populations. To investigate this relationship, we studied a coastal population of brown booby (Sula leucogaster brewsteri), a seabird with a carotenoid-based gular skin ornament. δ13C values from both feathers and blood plasma were negatively correlated with male gular colour, indicating birds that consumed more pelagic prey in offshore locations had more ornamented skin than those that fed on nearshore, benthic prey. This relationship was supported by our GPS tracking results, which revealed longer, more offshore foraging trips among highly ornamented males. Our data show that brown booby ornaments are honest indicators of foraging propensity; a link consistent with the rarity hypothesis and potentially driven by the concentration of carotenoids found in phytoplankton versus benthic algae. Carotenoid-based ornaments may reflect foraging tendencies in animals such as coastal predators that use food webs with distinct carotenoid profiles

Nonlinear optics via double dark resonances

Double dark resonances originate from a coherent perturbation of a system displaying electromagnetically induced transparency. We experimentally show and theoretically confirm that this leads to the possibility of extremely sharp resonances prevailing even in the presence of considerable Doppler broadening. A gas of 87Rb atoms is subjected to a strong drive laser and a weak probe laser and a radio frequency field, where the magnetic coupling between the Zeeman levels leads to nonlinear generation of a comb of sidebands.Comment: 6 pages, 9 figure

Flexoelectro-optic liquid crystal analog phase-only modulator with a 2π range and 1 kHz switching

We present a flexoelectro-optic liquid crystal (LC) analog phase modulator with >

Muscle Loss: The New Malnutrition Challenge in Clinical Practice

Recent definitions of malnutrition include low muscle mass within its diagnostic criteria. In fact, malnutrition is one of the main risk factors of skeletal muscle loss contributing to the onset of sarcopenia. However, differences in the screening and diagnosis of skeletal muscle loss, especially as a result of malnutrition in clinical and community settings, still occur mainly as techniques and thresholds used vary in clinical practice. The objectives of this position paper are firstly to emphasize the link between skeletal muscle loss and malnutrition-related conditions and secondly to raise awareness for the timely identification of loss of skeletal muscle mass and function in high risk populations. Thirdly to recognize the need to implement appropriate nutritional strategies for prevention and treatment of skeletal muscle loss and malnutrition across the healthcare continuum. Malnutrition needs to be addressed clinically as a muscle-related disorder and clinicians should integrate nutritional assessment with muscle mass measurements for optimal evaluation of these two interrelated entities to tailor interventions appropriately. The design of monitoring/evaluation and discharge plans need to include multimodal interventions with nutrition and physical exercise that are key to preserve patient’s muscle mass and function in clinical and community settings

Fast and low loss flexoelectro-optic liquid crystal phase modulator with a chiral nematic reflector

© 2019, The Author(s). In this paper, we demonstrate a flexoelectro-optic liquid crystal phase-only device that uses a chiral nematic reflector to achieve full 2π phase modulation. This configuration is found to be very tolerant to imperfections in the chiral nematic reflector provided that the flexoelectro-optic LC layer fulfils the half-wave condition. Encouragingly, the modulation in the phase, which operates at kHz frame rates, is also accompanied by low amplitude modulation. The configuration demonstrated herein is particularly promising for the development of next-generation liquid crystal on silicon spatial light modulators

Fast and low loss flexoelectro-optic liquid crystal phase modulator with a chiral nematic reflector

© 2019, The Author(s). In this paper, we demonstrate a flexoelectro-optic liquid crystal phase-only device that uses a chiral nematic reflector to achieve full 2π phase modulation. This configuration is found to be very tolerant to imperfections in the chiral nematic reflector provided that the flexoelectro-optic LC layer fulfils the half-wave condition. Encouragingly, the modulation in the phase, which operates at kHz frame rates, is also accompanied by low amplitude modulation. The configuration demonstrated herein is particularly promising for the development of next-generation liquid crystal on silicon spatial light modulators

Active Brownian Particles. From Individual to Collective Stochastic Dynamics

We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte