1,686 research outputs found

    An airborne FLIR detection and warning system for low altitude wind shear

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    It is shown through some preliminary flight measurement research that a forward looking infrared radiometer (FLIR) system can be used to successfully detect the cool downdraft of downbursts (microbusts/macrobursts) and thunderstorm gust front outflows that are responsible for most of the low altitude wind shear (LAWS) events. The FLIR system provides a much greater safety margin for the pilot than that provided by reactive designs such as inertial air speed systems. Preliminary results indicate that an advanced airborne FLIR system could provide the pilot with remote indication of microburst (MB) hazards along the flight path ahead of the aircraft. Results of a flight test of a prototype FLIR system show that a minimum warning time of one to four minutes (5 to 10 km), depending on aircraft speed, is available to the pilot prior to the microburst encounter

    Chromophore-bearing NH_2-terminal domains of phytochromes A and B determine their photosensory specificity and differential light lability

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    In early seedling development, far-red-light-induced deetiolation is mediated primarily by phytochrome A (phyA), whereas red-light-induced deetiolation is mediated primarily by phytochrome B (phyB). To map the molecular determinants responsible for this photosensory specificity, we tested the activities of two reciprocal phyA/phyB chimeras in diagnostic light regimes using overexpression in transgenic Arabidopsis. Although previous data have shown that the NH_2-terminal halves of phyA and phyB each separately lack normal activity, fusion of the NH_2-terminal half of phyA to the COOH-terminal half of phyB (phyAB) and the reciprocal fusion (phyBA) resulted in biologically active phytochromes. The behavior of these two chimeras in red and far-red light indicates: (i) that the NH2-terminal halves of phyA and phyB determine their respective photosensory specificities; (ii) that the COOH-terminal halves of the two photoreceptors are necessary for regulatory activity but are reciprocally inter-changeable and thus carry functionally equivalent determinants; and (iii) that the NH_2-terminal halves of phyA and phyB carry determinants that direct the differential light lability of the two molecules. The present findings suggest that the contrasting photosensory information gathered by phyA and phyB through their NH_2-terminal halves may be transduced to downstream signaling components through a common biochemical mechanism involving the regulatory activity of the COOH-terminal domains of the photoreceptors

    Photonic qubits, qutrits and ququads accurately prepared and delivered on demand

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    Reliable encoding of information in quantum systems is crucial to all approaches to quantum information processing or communication. This applies in particular to photons used in linear optics quantum computing (LOQC), which is scalable provided a deterministic single-photon emission and preparation is available. Here, we show that narrowband photons deterministically emitted from an atom-cavity system fulfill these requirements. Within their 500 ns coherence time, we demonstrate a subdivision into d time bins of various amplitudes and phases, which we use for encoding arbitrary qu-d-its. The latter is done deterministically with a fidelity >95% for qubits, verified using a newly developed time-resolved quantum-homodyne method.Comment: 5 pages, 4 figure

    Mindfulness-based interventions in multiple sclerosis : beneficial effects of Tai Chi on balance, coordination, fatigue and depression

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    BACKGROUND: Patients suffering from Multiple Sclerosis (MS) experience a wide array of symptoms, including balance problems, mobility impairment, fatigue and depression. Physical exercise has recently been acknowledged as a treatment option complementary to medication. However, information regarding putative effects of structured exercise programs on neurological symptoms is sparse. Tai Chi, a Chinese martial art incorporating physical exercise and mindfulness training, has been shown to yield health benefits in various neurological groups. It seems particularly suitable for patients with motoric deficits as it challenges coordination and balance. The purpose of the current study was to explore the therapeutic value of structured Tai Chi training for coordination, balance, fatigue and depression in mildly disabled MS patients. METHODS: A sample of 32 MS patients (Expanded Disability Status Scale, EDSS < 5) was examined. A structured Tai Chi course was devised and a Tai Chi group participated in two weekly sessions of 90Β minutes duration for six months, while a comparison group received treatment as usual (TAU). Both groups were examined prior to and following the six-months interval with regards to balance and coordination performance as well as measures of fatigue, depression and life satisfaction. RESULTS: Following the intervention, the Tai Chi group showed significant, consistent improvements in balance, coordination, and depression, relative to the TAU group (range of effect-sizes: partial Ξ·(2) = 0.16 – 0.20). Additionally, life satisfaction improved (partial Ξ·(2) = 0.31). Fatigue deteriorated in the comparison group, whereas it remained relatively stable in the Tai Chi group (partial Ξ·(2) = 0.24). CONCLUSIONS: The consistent pattern of results confirms that Tai Chi holds therapeutic potential for MS patients. Further research is needed to determine underlying working mechanisms, and to verify the results in a larger sample and different MS subgroups

    A model of fasciculation and sorting in mixed populations of axons

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    We extend a recently proposed model (Chaudhuri et al., EPL 87, 20003 (2009)) aiming to describe the formation of fascicles of axons during neural development. The growing axons are represented as paths of interacting directed random walkers in two spatial dimensions. To mimic turnover of axons, whole paths are removed and new walkers are injected with specified rates. In the simplest version of the model, we use strongly adhesive short-range inter-axon interactions that are identical for all pairs of axons. We generalize the model to adhesive interactions of finite strengths and to multiple types of axons with type-specific interactions. The dynamic steady state is characterized by the position-dependent distribution of fascicle sizes. With distance in the direction of axon growth, the mean fascicle size and emergent time scales grow monotonically, while the degree of sorting of fascicles by axon type has a maximum at a finite distance. To understand the emergence of slow time scales, we develop an analytical framework to analyze the interaction between neighboring fascicles.Comment: 19 pages, 13 figures; version accepted for publication in Phys Rev

    ΠžΠΏΡ‚ΠΈΠΌΠΈΠ·Π°Ρ†ΠΈΡ Π°ΠΏΠΏΠ°Ρ€Π°Ρ‚ΡƒΡ€Π½ΠΎΠ³ΠΎ оформлСния процСсса дСгидрирования Π²Ρ‹ΡΡˆΠΈΡ… Π°Π»ΠΊΠ°Π½ΠΎΠ² с использованиСм ΠΌΠ΅Ρ‚ΠΎΠ΄Π° матСматичСского модСлирования

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    ΠŸΡ€Π΅Π΄Π»ΠΎΠΆΠ΅Π½ Π½ΠΎΠ²Ρ‹ΠΉ способ ΠΏΠΎΠ²Ρ‹ΡˆΠ΅Π½ΠΈΡ эффСктивности Ρ€Π°Π±ΠΎΡ‚Ρ‹ Ρ€Π΅Π°ΠΊΡ‚ΠΎΡ€Π½ΠΎΠ³ΠΎ Π±Π»ΠΎΠΊΠ° дСгидрирования ΠΏΠ°Ρ€Π°Ρ„ΠΈΠ½ΠΎΠ² с использованиСм матСматичСской ΠΌΠΎΠ΄Π΅Π»ΠΈ, ΡƒΡ‡ΠΈΡ‚Ρ‹Π²Π°ΡŽΡ‰Π΅ΠΉ Π²Π·Π°ΠΈΠΌΠ½ΠΎΠ΅ влияниС процСссов, ΠΏΡ€ΠΎΡ‚Π΅ΠΊΠ°ΡŽΡ‰ΠΈΡ… Π² Π°ΠΏΠΏΠ°Ρ€Π°Ρ‚Π°Ρ… Ρ…ΠΈΠΌΠΈΠΊΠΎ-тСхнологичСской систСмы. ΠŸΡ€ΠΎΠ²Π΅Π΄Π΅Π½Π° числСнная ΠΎΡ†Π΅Π½ΠΊΠ° влияния химичСского состава ΡΡ‹Ρ€ΡŒΡ, тСхнологичСских Ρ€Π΅ΠΆΠΈΠΌΠΎΠ² ΠΈ стСпСни Π΄Π΅Π·Π°ΠΊΡ‚ΠΈΠ²Π°Ρ†ΠΈΠΈ ΠΊΠ°Ρ‚Π°Π»ΠΈΠ·Π°Ρ‚ΠΎΡ€Π° Π½Π° ΡΡ„Ρ„Π΅ΠΊΡ‚ΠΈΠ²Π½ΠΎΡΡ‚ΡŒ Ρ€Π°Π±ΠΎΡ‚Ρ‹ Π°ΠΏΠΏΠ°Ρ€Π°Ρ‚ΠΎΠ² Ρ…ΠΈΠΌΠΈΠΊΠΎ-тСхнологичСской схСмы ΠΏΡ€ΠΎΠΌΡ‹ΡˆΠ»Π΅Π½Π½ΠΎΠΉ установки дСгидрирования
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