2,837 research outputs found

    Effect of CH4_{4} addition on excess electron mobility in liquid Kr

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    The excess electrons mobility μ\mu has been measured recently in liquid mixtures of Kr and CH4_{4} as a function of the electric field up to E≈104V/cmE\approx 10^{4} V/cm and of the CH4_{4} concentration xx up to x≈10x \approx 10 % , at temperatures T≈130K,T\approx 130 K, fairly close to the normal boiling point of Kr (Tb≈120K)(T_{b}\approx 120 K)(folegani). We present here new data which extend the previous set in the region of low electric field. The experimental results are interpreted in terms of a kinetic model previously proposed to explain the concentration dependent behavior of μ\mu in liquid Ar--Kr and Ar--Xe mixtures. The main result is that CH4_{4} is more effective in enhancing energy--transfer rather than momentum--transfer in comparison with mixtures of liquified noble gases. The field dependence of μ\mu is quite complicate. In particular, at intermediate values of the field, there appears to be a crossover between two different electric--field dependent behaviors of μ.\mu. The electric field strength at crossover is well correlated with the concentration of CH4._{4}. This fact suggests that different excitations of the molecular solute might be involved in the momentum-- and energy--transfer processes for different values of the mean electron energy.Comment: 17, pages,7 figures, RevTeX4, submitted to J.Chem.Phy

    First results from the new PVLAS apparatus: a new limit on vacuum magnetic birefringence

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    Several groups are carrying out experiments to observe and measure vacuum magnetic birefringence, predicted by Quantum Electrodynamics (QED). We have started running the new PVLAS apparatus installed in Ferrara, Italy, and have measured a noise floor value for the unitary field magnetic birefringence of vacuum Δnu(vac)=(4±20)×10−23\Delta n_u^{\rm (vac)}= (4\pm 20) \times 10^{-23} T−2^{-2} (the error represents a 1σ\sigma deviation). This measurement is compatible with zero and hence represents a new limit on vacuum magnetic birefringence deriving from non linear electrodynamics. This result reduces to a factor 50 the gap to be overcome to measure for the first time the value of Δnu(vac,QED)\Delta n_u^{\rm (vac,QED)} predicted by QED: Δnu(vac,QED)=4×10−24\Delta n_u^{\rm (vac,QED)}= 4\times 10^{-24} ~T−2^{-2}. These birefringence measurements also yield improved model-independent bounds on the coupling constant of axion-like particles to two photons, for masses greater than 1 meV, along with a factor two improvement of the fractional charge limit on millicharged particles (fermions and scalars), including neutrinos

    New PVLAS model independent limit for the axion coupling to γγ\gamma\gamma for axion masses above 1meV

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    During 2014 the PVLAS experiment has started data taking with a new apparatus installed at the INFN Section of Ferrara, Italy. The main target of the experiment is the observation of magnetic birefringence of vacuum. According to QED, the ellipticity generated by the magnetic birefringence of vacuum in the experimental apparatus is expected to be ψ(QED)≈5×10−11\psi^{\rm(QED)} \approx 5\times10^{-11}. No ellipticity signal is present so far with a noise floor ψ(noise)≈2.5×10−9\psi^{\rm(noise)} \approx 2.5\times10^{-9} after 210 hours of data taking. The resulting ellipticity limit provides the best model independent upper limit on the coupling of axions to γγ\gamma\gamma for axion masses above 10−310^{-3}eV

    Measurement of the Cotton Mouton effect of water vapour

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    In this paper we report on a measurement of the Cotton Mouton effect of water vapour. Measurement performed at room temperature (T=301T=301 K) with a wavelength of 1064 nm gave the value Δnu=(6.67±0.45)⋅10−15\Delta n_u = (6.67 \pm 0.45) \cdot 10^{-15} for the unit magnetic birefringence (1 T magnetic field and atmospheric pressure)

    Use of Annual Self-Reseeding Legumes in an Oak Forest in Central Italy

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    A trial has been carried out for three years in an oak coppice geometrically thinned out of Mediterranean Central Italy, about the functioning of a pastoral system made by four different resources: native pasture, subterranean clover (Trifolium brachycalycinum Katzn. et Morley) in pure stand, strips thinned out and firebreaks improved with oversown subclover, all grazed by sheep. Subclover increased the forage yield and improved the palatabilty of the pasture and the regularity of grazing; the higher biomass intake by animals reduced the quantity of dried biomass in summer and contributed to keep low either fire hazards or flame diffusion speed. Data underlined the importance of deferred grazing and of the combination of different native or improved resources on the seasonal distribution of production and animal intake

    Affective Temperaments and Somatization Among Unipolar Depression Patients and Healthy Controls

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    Introduction Literature describes important comorbidity rates between somatization and mood disorders. Furthermore, there are data suggesting an association between affective temperament and somatization traits in healthy subjects. Objective In the present observational study, we investigated affective temperaments and somatization aspects in clinical and healthy samples. Aim The study focused on differences between unipolar depressive inpatients (DEP) and controls (C). Method We administered to 20 DEP and 20 C following questionnaires: Mini International Neuropsychiatric Interview (MINI), 17-item Self Rating Depression Scale (SDS), Hypomania check list 32(HCL-32), Self Rating Anxiety Scale (SAS), DCPR diagnostic criteria for psychosomatic research, Brief TEMPS-A, Modified Somatic Perception Questionnaire (MSPQ), Somatosensory Amplification Scale-SSAS. DEP and C were matched for age, sex and marital status. Result About temperaments, ANOVA showed that DEP were more cyclothymic (p Conclusion Our data suggest that DEP present an important affective temperamental dysregulation. Relative to somatization aspects, DEP show a greater vulnerability than C

    (2-Aminobenzothiazole)-Methyl-1,1-bisphosphonic acids: Targeting matrix metalloproteinase 13 inhibition to the bone

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    Matrix Metalloproteinases (MMPs) are a family of secreted and membrane-bound enzymes, of which 24 isoforms are known in humans. These enzymes degrade the proteins of the extracellular matrix and play a role of utmost importance in the physiological remodeling of all tissues. However, certain MMPs, such as MMP-2, -9, and -13, can be overexpressed in pathological states, including cancer and metastasis. Consequently, the development of MMP inhibitors (MMPIs) has been explored for a long time as a strategy to prevent and hinder metastatic growth, but the important side effects linked to promiscuous inhibition of MMPs prevented the clinical use of MMPIs. Therefore, several strategies were proposed to improve the therapeutic profile of this pharmaceutical class, including improved selectivity toward specific MMP isoforms and targeting of specific organs and tissues. Combining both approaches, we conducted the synthesis and preliminary biological evaluation of a series of (2-aminobenzothiazole)-methyl-1,1-bisphosphonic acids active as selective inhibitors of MMP-13 via in vitro and in silico studies, which could prove useful for the treatment of bone metastases thanks to the bone-targeting capabilities granted by the bisphosphonic acid group
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