446 research outputs found

    Alpine Space Prospective Study. Sustainable territorial development in the Alpine Space: Towards long term transnational cooperation

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    This "Prospective Study" argues that a long term transnational cooperation will be able to pursue the sustainable territorial development in the Alpine Space only at the condition of a substantial improvement of the current experience. This regards an increased awareness of the complexity of issues and challenges currently at stake in the Alpine area but especially, in this light, the capacity of involving all relevant institutional and socioeconomic stakeholders in the building of shared transnational strategie

    Alpine Space Prospective Study. Sustainable territorial development in the Alpine Space: Towards long term transnational cooperation

    Get PDF
    This "Prospective Study" argues that a long term transnational cooperation will be able to pursue the sustainable territorial development in the Alpine Space only at the condition of a substantial improvement of the current experience. This regards an increased awareness of the complexity of issues and challenges currently at stake in the Alpine area but especially, in this light, the capacity of involving all relevant institutional and socioeconomic stakeholders in the building of shared transnational strategies

    Pulsed beams as field probes for precision measurement

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    We describe a technique for mapping the spatial variation of static electric, static magnetic, and rf magnetic fields using a pulsed atomic or molecular beam. The method is demonstrated using a beam designed to measure the electric dipole moment of the electron. We present maps of the interaction region, showing sensitivity to (i) electric field variation of 1.5 V/cm at 3.3 kV/cm with a spatial resolution of 15 mm; (ii) magnetic field variation of 5 nT with 25 mm resolution; (iii) radio-frequency magnetic field amplitude with 15 mm resolution. This new diagnostic technique is very powerful in the context of high-precision atomic and molecular physics experiments, where pulsed beams have not hitherto found widespread application.Comment: 6 pages, 12 figures. Figures heavily compressed to comply with arxiv's antediluvian file-size polic

    Mean field ground state of a spin-1 condensate in a magnetic field

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    We revisit the topic of the mean field ground state of a spin-1 atomic condensate inside a uniform magnetic field (BB) under the constraints that both the total number of atoms (NN) and the magnetization (M\cal M) are conserved. In the presence of an internal state (spin component) independent trap, we also investigate the dependence of the so-called single spatial mode approximation (SMA) on the magnitude of the magnetic field and M{\cal M}. Our result indicate that the quadratic Zeeman effect is an important factor in balancing the mean field energy from elastic atom-atom collisions that are known to conserve both NN and M\cal M.Comment: 13 pages, 9 figures, to be published in New J. Phys. (http://www.njp.org/

    Metrological characterization of the pulsed Rb clock with optical detection

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    We report on the implementation and the metrological characterization of a vapor-cell Rb frequency standard working in pulsed regime. The three main parts that compose the clock, physics package, optics and electronics, are described in detail in the paper. The prototype is designed and optimized to detect the clock transition in the optical domain. Specifically, the reference atomic transition, excited with a Ramsey scheme, is detected by observing the interference pattern on a laser absorption signal. \ The metrological analysis includes the observation and characterization of the clock signal and the measurement of frequency stability and drift. In terms of Allan deviation, the measured frequency stability results as low as 1.7×1013 τ1/21.7\times 10^{-13} \ \tau^{-1/2}, τ\tau being the averaging time, and reaches the value of few units of 101510^{-15} for τ=104\tau=10^{4} s, an unprecedent achievement for a vapor cell clock. We discuss in the paper the physical effects leading to this result with particular care to laser and microwave noises transferred to the clock signal. The frequency drift, probably related to the temperature, stays below 101410^{-14} per day, and no evidence of flicker floor is observed. \ We also mention some possible improvements that in principle would lead to a clock stability below the 101310^{-13} level at 1 s and to a drift of few units of 101510^{-15} per day

    Compostos fenólicos e atividade antioxidante de grãos de arroz de pericarpo vermelho e de pericarpo preto.

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    Objetivou-se, com o presente estudo, avaliar o teor de compostos fenólicos livres e complexados e a atividade antioxidante pelo método ABTS, tanto da fração de fenólicos livres como de fenólicos complexados, de grãos de duas cultivares de arroz de pericarpo preto (IAC 600 e SCS 120) e de duas cultivares de arroz de pericarpo vermelho (BRS 902 e SCS 119).Os grãos de arroz foram colhidos no campo experimental da Embrapa Arroz e Feijão, em Santo Antônio de Goiás, Goiás, Brasil

    Investigation of microwave transitions and nonlinear magneto-optical rotation in anti-relaxation-coated cells

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    Using laser optical pumping, widths and frequency shifts are determined for microwave transitions between ground-state hyperfine components of 85^{85}Rb and 87^{87}Rb atoms contained in vapor cells with alkane anti-relaxation coatings. The results are compared with data on Zeeman relaxation obtained in nonlinear magneto-optical rotation (NMOR) experiments, a comparison important for quantitative understanding of spin-relaxation mechanisms in coated cells. By comparing cells manufactured over a forty-year period we demonstrate the long-term stability of coated cells, an important property for atomic clocks and magnetometers

    A high-flux 2D MOT source for cold lithium atoms

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    We demonstrate a novel 2D MOT beam source for cold 6Li atoms. The source is side-loaded from an oven operated at temperatures in the range 600<T<700 K. The performance is analyzed by loading the atoms into a 3D MOT located 220 mm downstream from the source. The maximum recapture rate of ~10^9 /s is obtained for T=700 K and results in a total of up to 10^10 trapped atoms. The recaptured fraction is estimated to be 30(10)% and limited by beam divergence. The most-probable velocity in the beam (alpha_z) is varied from 18 to 70 m/s by increasing the intensity of a push beam. The source is quite monochromatic with a full-width at half maximum velocity spread of 11 m/s at alpha_z=36 m/s, demonstrating that side-loading completely eliminates beam contamination by hot vapor from the oven. We identify depletion of the low-velocity tail of the oven flux as the limiting loss mechanism. Our approach is suitable for other atomic species.Comment: 13 pages,9 figures, submitted to Phys.Rev.

    Interacting Dark Resonances: Interference Effects Induced by Coherently Altered Quantum Superpositions

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    We predict the possibility of sharp, high-contrast resonances in the optical response of a broad class of systems, wherein interference effects are generated by coherent perturbation or interaction of dark states. The properties of these resonances can be manipulated to design a desired atomic response.Comment: 4 pages, 3 figures, RevTeX, submitted to PRL; changed three numbers in Fig. 3 (caption

    Niemann-Pick disease type C

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    Niemann-Pick C disease (NP-C) is a neurovisceral atypical lysosomal lipid storage disorder with an estimated minimal incidence of 1/120 000 live births. The broad clinical spectrum ranges from a neonatal rapidly fatal disorder to an adult-onset chronic neurodegenerative disease. The neurological involvement defines the disease severity in most patients but is typically preceded by systemic signs (cholestatic jaundice in the neonatal period or isolated spleno- or hepatosplenomegaly in infancy or childhood). The first neurological symptoms vary with age of onset: delay in developmental motor milestones (early infantile period), gait problems, falls, clumsiness, cataplexy, school problems (late infantile and juvenile period), and ataxia not unfrequently following initial psychiatric disturbances (adult form). The most characteristic sign is vertical supranuclear gaze palsy. The neurological disorder consists mainly of cerebellar ataxia, dysarthria, dysphagia, and progressive dementia. Cataplexy, seizures and dystonia are other common features. NP-C is transmitted in an autosomal recessive manner and is caused by mutations of either the NPC1 (95% of families) or the NPC2 genes. The exact functions of the NPC1 and NPC2 proteins are still unclear. NP-C is currently described as a cellular cholesterol trafficking defect but in the brain, the prominently stored lipids are gangliosides. Clinical examination should include comprehensive neurological and ophthalmological evaluations. The primary laboratory diagnosis requires living skin fibroblasts to demonstrate accumulation of unesterified cholesterol in perinuclear vesicles (lysosomes) after staining with filipin. Pronounced abnormalities are observed in about 80% of the cases, mild to moderate alterations in the remainder ("variant" biochemical phenotype). Genotyping of patients is useful to confirm the diagnosis in the latter patients and essential for future prenatal diagnosis. The differential diagnosis may include other lipidoses; idiopathic neonatal hepatitis and other causes of cholestatic icterus should be considered in neonates, and conditions with cerebellar ataxia, dystonia, cataplexy and supranuclear gaze palsy in older children and adults. Symptomatic management of patients is crucial. A first product, miglustat, has been granted marketing authorization in Europe and several other countries for specific treatment of the neurological manifestations. The prognosis largely correlates with the age at onset of the neurological manifestations
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