2,571 research outputs found

    Synthesis of Some Quaternary Bases Related to Tropine. Studies in the Muscarine Series. V

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    In connection with earlier work on muscarine from this laboratory the following compounds have been synthesized: from DL-tropinic acid dimethyl ester (I) 1-methyl-2-hydroxymethyl-5-(2 \u27-hydroxyethylpyrrolidine (II) and 1,1-dimethyl-2-hydroxymethyl-5-(2\u27-hydroxyethyl)pyrrolidinium iodide (III) were prepared; from 1,2,6-trimethyl-4-hydroxypiperidine and methyl iodide 1,1,2,6-tetramethyl-4-hydroxypiperidinium iodide (IV) was prepared; catalytic hydrogention of 1-methyl-3-hydroxypyridone-(4) gave 1-methyl-3,4-dihydroxypiperidine, from which, by reacting with methyl iodide, 1,1-dimethyl-3,4-dihydroxypiperidinium iodide (V) was obtained

    Pathogenicity of Botryosphaeriaceae and Phytophthora species associated with Paulownia dieback, canker and root rot in Italy

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    In recent years, an unusual decline and mortality has been observed inPaulownia plantations throughout the Marche region (Central Italy). Given the eco-nomic importance of this emerging forest crop, a study was conducted to determinewhich pathogens are directly involved in this syndrome. Field surveys performed intwo plantations revealed the widespread occurrence of severe disease symptoms suchas leaf chlorosis, crown thinning, shoot and branch dieback, sunken cankers, epicormicshoots and root rot. Disease incidence was also assessed by aerial remote sensing (RS)technologies using drones. Symptomatic samples collected from both stem and roottissues yielded fungal and fungal-like colonies representing two distinct families: Bot-ryosphaeriaceae and Peronosporaceae. Morphological and DNA sequence data revealedfive distinct species, identified as Macrophomina phaseolina and Botryosphaeria doth-idea (Botryosphaeriaceae), Phytophthora pseudocryptogea, P. citrophthora and P. eryth-roseptica (Peronosporaceae). Given that all species are reported here for the first timeon Paulownia, Koch’s postulates were satisfied inoculating the three Phytophthora spe-cies and two Botryosphaeriaceae at the collar of the stem of potted 1-year-old rootedcuttings in June 2023. Thirty days after inoculation, all plants showed the same symp-toms as those observed in the field

    Acoustic comfort depends on the psychological state of the individual

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    Recent studies have shown that comfort can be influenced more by psychological processes than from the characteristics of environmental stimulation. This is relevant for different industrial sectors, where comfort is defined only as a function of the intensity of external stimuli. In the present study, we measured physiological and psychological comfort during the exposure to four levels of acoustic noise [from 45 to 55 dB(A)] corresponding to different comfort classes inside a full-scale mock-up of a cruise ship cabin. We found an increase of psychological and physiological discomfort for higher noise intensities, but not for all the intensities defining the comfort classes. Furthermore, we found that negative psychological states determine a lower physiological sensitivity to acoustic noise variations compared to positive states. Our results show that, at normal/low intensities, psychological processes have a greater role in determining acoustic comfort when compared to the stimulus intensity. Practitioner Summary: This study shows that psychological factors can be more relevant in determining acoustic comfort inside a ship cabin than the intensity of acoustic stimulus itself. This finding suggests that the cruise industry should consider not only the engineering measurements when evaluating comfort on board, but also the passenger\u2019 psychological state. Abbreviations: AIC: akaike information criterion; CCT: colour correlated temperature; cd/m2: candela/square meters; df: degrees of freedom; F-test: Fisher's test; HF: high frequency; HR: heart rate; HRV: heart rate variability; HSV: hue saturation value; K: kelvin; LF: low frequency; LF/HF: low frequency to high frequency ratio; lme: linear mixed effects; ms: milliseconds; nu: normalized unit; p: p value; pNN50: percentage of adjacent pairs of normal to normal RR intervals differing by more than 50 milliseconds; r2: coefficient of determination; rc: concordance correlation coefficient; RMSSD: square root of the mean normal to normal RR interval; SD: standard deviation; SDNN: standard deviation of normal to normal RR intervals; SEM: standard error of the mean; t-test: student's tests; \u3c72: chi-square test

    Ultrafast Resonant Polarization Interferometry: Towards the First Direct Detection of Vacuum Polarization

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    Vacuum polarization, an effect predicted nearly 70 years ago, is still yet to be directly detected despite significant experimental effort. Previous attempts have made use of large liquid-helium cooled electromagnets which inadvertently generate spurious signals that mask the desired signal. We present a novel approach for the ultra-sensitive detection of optical birefringence that can be usefully applied to a laboratory detection of vacuum polarization. The new technique has a predicted birefringence measurement sensitivity of Δn∌1020\Delta n \sim 10^{20} in a 1 second measurement. When combined with the extreme polarizing fields achievable in this design we predict that a vacuum polarization signal will be seen in a measurement of just a few days in duration.Comment: 9 pages, 2 figures. submitted to PR

    Experimental observation of optical rotation generated in vacuum by a magnetic field

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    We report the experimental observation of a light polarization rotation in vacuum in the presence of a transverse magnetic field. Assuming that data distribution is Gaussian, the average measured rotation is (3.9+/-0.5)e-12 rad/pass, at 5 T with 44000 passes through a 1m long magnet, with lambda = 1064 nm. The relevance of this result in terms of the existence of a light, neutral, spin-zero particle is discussed.Comment: 11 pages, 4 figures, submitted to Physical Review Letters Comment to version 2: minor changes to abstract and final discussion. Added 2 references Comment to version 3: corrected minor typographical errors, eliminated the distinction between scalar and pseudoscalar in the particle interpretation of the resul

    Optical production and detection of dark matter candidates

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    The PVLAS collaboration is at present running, at the Laboratori Nazionali di Legnaro of I.N.F.N., Padova, Italy, a very sensitive optical ellipsometer capable of measuring the small rotations or ellipticities which can be acquired by a linearly polarized laser beam propagating in vacuum through a transverse magnetic feld (vacuum magnetic birefringence). The apparatus will also be able to set new limits on mass and coupling constant of light scalar/pseudoscalar particles coupling to two photons by both producing and detecting the hypothetical particles. The axion, introduced to explain parity conservation in strong interactions, is an example of this class of particles, all of which are considered possible dark matter candidates. The PVLAS apparatus consists of a very high finesse (> 140000), 6.4 m long, Fabry-Perot cavity immersed in an intense dipolar magnetic field (~6.5 T). A linearly polarized laser beam is frequency locked to the cavity and analysed, using a heterodyne technique, for rotation and/or ellipticity acquired within the magnetic field.Comment: presented at "Frontier Detectors for Frontier Physics - 8th Pisa Meeting on Advanced Detectors - May 21-27, 2000" to appear in: Nucl.Instr. and Meth.

    Limits on Low Energy Photon-Photon Scattering from an Experiment on Magnetic Vacuum Birefringence

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    Experimental bounds on induced vacuum magnetic birefringence can be used to improve present photon-photon scattering limits in the electronvolt energy range. Measurements with the PVLAS apparatus (E. Zavattini {\it et al.}, Phys. Rev. D {\bf77} (2008) 032006) at both λ=1064\lambda = 1064 nm and 532 nm lead to bounds on the parameter {\it Ae_{e}}, describing non linear effects in QED, of Ae(1064)<6.6⋅10−21A_{e}^{(1064)} < 6.6\cdot10^{-21} T−2^{-2} @ 1064 nm and Ae(532)<6.3⋅10−21A_{e}^{(532)} < 6.3\cdot10^{-21} T−2^{-2} @ 532 nm, respectively, at 95% confidence level, compared to the predicted value of Ae=1.32⋅10−24A_{e}=1.32\cdot10^{-24} T−2^{-2}. The total photon-photon scattering cross section may also be expressed in terms of AeA_e, setting bounds for unpolarized light of ÏƒÎłÎł(1064)<4.6⋅10−62\sigma_{\gamma\gamma}^{(1064)} < 4.6\cdot10^{-62} m2^{2} and ÏƒÎłÎł(532)<2.7⋅10−60\sigma_{\gamma\gamma}^{(532)} < 2.7\cdot10^{-60} m2^{2}. Compared to the expected QED scattering cross section these results are a factor of ≃2⋅107\simeq2\cdot10^{7} higher and represent an improvement of a factor about 500 on previous bounds based on ellipticity measurements and of a factor of about 101010^{10} on bounds based on direct stimulated scattering measurements

    New PVLAS results and limits on magnetically induced optical rotation and ellipticity in vacuum

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    IIn 2006 the PVLAS collaboration reported the observation of an optical rotation generated in vacuum by a magnetic field. To further check against possible instrumental artifacts several upgrades to the PVLAS apparatus have been made during the last year. Two data taking runs, at the wavelength of 1064 nm, have been performed in the new configuration with magnetic field strengths of 2.3 T and 5 T. The 2.3 T field value was chosen in order to avoid stray fields. The new observations do not show the presence of a rotation signal down to the levels of 1.2⋅10−81.2\cdot 10^{-8} rad at 5 T and 1.0⋅10−81.0\cdot 10^{-8} rad at 2.3 T (at 95% c.l.) with 45000 passes in the magnetic field zone. In the same conditions no ellipticity signal was detected down to 1.4⋅10−81.4\cdot 10^{-8} at 2.3 T (at 95% c.l.), whereas at 5 T a signal is still present. The physical nature of this ellipticity as due to an effect depending on B2B^2 can be excluded by the measurement at 2.3 T. These new results completely exclude the previously published magnetically induced vacuum dichroism results, indicating that they were instrumental artifacts. These new results therefore also exclude the particle interpretation of the previous PVLAS results as due to a spin zero boson. The background ellipticity at 2.3 T can be used to determine a new limit on the total photon-photon scattering cross section of ÏƒÎłÎł<4.5⋅10−34\sigma_{\gamma\gamma} < 4.5 \cdot10^{-34} barn at 95% c.l..Comment: 25 pages, 7 figures Main changes rel. to v.2: minor changes to abstract, replaced Figures 4,5,6, corrected typographical errors. Paper submitted to Physical Review

    The pi -> pi pi process in nuclei and the restoration of chiral symmetry

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    The results of an extensive campaign of measurements of the pi -> pi pi process in the nucleon and nuclei at intermediate energies are presented. The measurements were motivated by the study of strong pi pi correlations in nuclei. The analysis relies on the composite ratio C_{pi pi}^A, which accounts for the clear effect of the nuclear medium on the (pi pi) system. The comparison of the C_{pi pi}^A distributions for the (pi pi)_{I=J=0} and (pi pi)_{I=0,J=2} systems to the model predictions indicates that the C_{pi pi}^A behavior in proximity of the 2m_pi threshold is explainable through the partial restoration of chiral symmetry in nuclei.Comment: accepted for publication in Nucl. Phys.

    Σ−p\Sigma^- p emission rates in K−K^- absorptions at rest on 6^6Li, 7^7Li, 9^{9}Be, 13^{13}C and 16^{16}O

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    An experimental study of the Kstop−A→Σ−pAâ€ČK^-_{stop}A\rightarrow \Sigma^- p A' reaction on A=6A=^6Li, 7^7Li, 9^9Be, 13^{13}C and 16^{16}O pp-shell nuclei is presented. The data were collected by the FINUDA spectrometer operating at the DAΊ\PhiNE ϕ\phi-factory (LNF-INFN, Italy). Emission rates for the reaction in the mentioned nuclei are measured and compared with the few existing data. The spectra of several observables are discussed; indications of Quasi-Free absorptions by a (np)(np) pair embedded in the AA nucleus can be obtained from the study of the missing mass distributions.Comment: Version accepted by PR
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