2,514 research outputs found
Synthesis of Some Quaternary Bases Related to Tropine. Studies in the Muscarine Series. V
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
Acoustic comfort depends on the psychological state of the individual
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
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 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
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
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
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 nm and 532 nm lead to
bounds on the parameter {\it A}, describing non linear effects in QED, of
T @ 1064 nm and T @ 532 nm, respectively, at 95% confidence level,
compared to the predicted value of T. The
total photon-photon scattering cross section may also be expressed in terms of
, setting bounds for unpolarized light of m and m. Compared to the expected QED scattering cross
section these results are a factor of higher and represent
an improvement of a factor about 500 on previous bounds based on ellipticity
measurements and of a factor of about on bounds based on direct
stimulated scattering measurements
New PVLAS results and limits on magnetically induced optical rotation and ellipticity in vacuum
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 rad at 5 T and 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 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 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 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
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.
emission rates in absorptions at rest on Li, Li, Be, C and O
An experimental study of the reaction
on Li, Li, Be, C and O -shell nuclei is
presented. The data were collected by the FINUDA spectrometer operating at the
DANE -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 pair embedded in the nucleus can be obtained from
the study of the missing mass distributions.Comment: Version accepted by PR
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