1,623 research outputs found
Determination of the s-wave Scattering Length of Chromium
We have measured the deca-triplet s-wave scattering length of the bosonic
chromium isotopes Cr and Cr. From the time constants for
cross-dimensional thermalization in atomic samples we have determined the
magnitudes and ,
where . By measuring the rethermalization rate of Cr over a
wide temperature range and comparing the temperature dependence with the
effective-range theory and single-channel calculations, we have obtained strong
evidence that the sign of is positive. Rescaling our Cr
model potential to Cr strongly suggests that is positive,
too.Comment: v3: corrected typo in y-axis scaling of Figs. 3 and
Precise determination of Li cold collision parameters by radio-frequency spectroscopy on weakly bound molecules
We employ radio-frequency spectroscopy on weakly bound Li molecules
to precisely determine the molecular binding energies and the energy splittings
between molecular states for different magnetic fields. These measurements
allow us to extract the interaction parameters of ultracold Li atoms based
on a multi-channel quantum scattering model. We determine the singlet and
triplet scattering lengths to be and (1
= 0.0529177 nm), and the positions of the broad Feshbach resonances in
the energetically lowest three wave scattering channels to be 83.41(15) mT,
69.04(5) mT, and 81.12(10) mT
The c4 atriplex halimus vs. The c3 atriplex hortensis: Similarities and differences in the salinity stress response
open7noSoil properties and the ability to sustain agricultural production are seriously impaired by salinity. The cultivation of halophytes is seen as a solution to cope with the problem. In this framework, a greenhouse pot experiment was set up to assess salinity response in the perennial C4 species Atriplex halimus, and in the following three cultivars of the annual C3 Atriplex hortensis: green, red, and scarlet. The four genotypes were grown for 35 days with water salinity (WS) ranging from 0 to 360 mM NaCl. Plant height and fresh weight (FW) increased at 360 vs. 0 WS. The stomatal conductance (GS) and transpiration rate (E) were more severely affected by salinity in the C4 A. halimus than in the C3 species A. hortensis. This was reflected in a lower leaf water potential indicating stronger osmotic adjustment, and a higher relative water content associated with more turgid leaves, in A. halimus than A. hortensis. In a PCA including all the studied traits, the GS and E negatively correlated to the FW, which, in turn, positively correlated with Na concentration and intrinsic water use efficiency (iWUE), indicating that reduced gas exchange associated with Na accumulation contributed to sustain iWUE under salinity. Finally, FTIR spectroscopy showed a reduced amount of pectin, lignin, and cellulose under salinity, indicating a weakened cell wall structure. Overall, both species were remarkably adapted to salinity: From an agronomic perspective, the opposite strategies of longer vs. faster soil coverage, involved by the perennial A. halimus vs. the annual A. hortensis cv. scarlet, are viable natural remedies for revegetating marginal saline soils and increasing soil organic carbon.openCalone R.; Cellini A.; Manfrini L.; Lambertini C.; Gioacchini P.; Simoni A.; Barbanti L.Calone R.; Cellini A.; Manfrini L.; Lambertini C.; Gioacchini P.; Simoni A.; Barbanti L
Metabolic Bile Acid Profile Impairments in Dogs Affected by Chronic Inflammatory Enteropathy
Bile acids (BAs), endogenous acidic steroids synthetized from cholesterol in the liver, play a key role in the gut–liver axis physiopathology, including in hepatotoxicity, intestinal inflammatory processes, and cholesterol homeostasis. Faecal Oxo-BAs, relatively stable intermediates of oxidation/epimerization reactions of the BA hydroxyls, could be relevant to investigating the crosstalk in the liver–gut axis and the relationship between diseases and alterations in microbiota composition. A paucity of information currently exists on faecal BA profiles in dogs with and without chronic inflammatory enteropathy (CIE). Comprehensive assessment of 31 molecules among faecal BAs and related microbiota metabolites was conducted with high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). Odds ratios (ORs) for associations of BAs with CIE were estimated using logistic regression. Principal component analysis was performed to find differences between the control and pathological dogs. Higher levels of primary BAs and muricholic acids, and lower levels of secondary BAs were found in pathological dogs. Higher concentrations in faecal oxo-metabolites were associated with the absence of CIE (OR < 1). This study shows a marked difference in faecal BA profiles between dogs with and without CIE. Further research will be needed to better understand the role of oxo-BAs and muricholic acids in CIE dogs
Multichannel quantum-defect theory for ultracold atom-ion collisions
We develop an analytical model for ultracold atom-ion collisions using the
multichannel quantum-defect formalism. The model is based on the analytical
solutions of the r^-4 long-range potential and on the application of a frame
transformation between asymptotic and molecular bases. This approach allows the
description of the atom-ion interaction in the ultracold domain in terms of
three parameters only: the singlet and triplet scattering lengths, assumed to
be independent of the relative motion angular momentum, and the lead dispersion
coefficient of the asymptotic potential. We also introduce corrections to the
scattering lengths that improve the accuracy of our quantum-defect model for
higher order partial waves, a particularly important result for an accurate
description of shape and Feshbach resonances at finite temperature. The theory
is applied to the system composed of a 40Ca+ ion and a Na atom, and compared to
numerical coupled-channel calculations carried out using ab initio potentials.
For this particular system, we investigate the spectrum of bound states, the
rate of charge-transfer processes, and the collision rates in the presence of
magnetic Feshbach resonances at zero and finite temperature.Comment: 39 pages, 21 figure
Tropospheric Ozone In A Mountain Forest Area: Spatial Distribution And Its Relation With Meteorology And Emission Sources
Biological injuries to forest ecosystems in two lateral valleys of Valtellina (Italy) have been
studied. The selected areas are characterized by different forest novel decline symptoms and
ozone concentration levels. Analyses of meteorological and air quality data collected by fixed
and mobile stations located in the two valleys are presented. Ozone concentration has been
measured both by passive samplers and continues analyzers and the ozone vertical gradient in
one valley has been determined. In order to investigate the relation between emission sources,
ambient ozone levels and plant biological injuries, a modeling research project has been
started. As preliminary results the wind field obtained by the application of two diagnostic
meteorological models, MINERVE and CALMET, and the computation of the biogenic
emissions are presented. Some examples of spatial distribution and temporal trend of the most
important pollutants emitted by plants are discussed
Generation of a flat-top laser beam for gravitational wave detectors by means of a nonspherical Fabry-Perot resonator
We have tested a new kind of Fabry-Perot long-baseline optical resonator proposed to reduce the thermal noise sensitivity of gravitational wave interferometric detectors--the "mesa beam" cavity--whose flat top beam shape is achieved by means of an aspherical end mirror. We present the fundamental mode intensity pattern for this cavity and its distortion due to surface imperfections and tilt misalignments, and contrast the higher order mode patterns to the Gauss-Laguerre modes of a spherical mirror cavity. We discuss the effects of mirror tilts on cavity alignment and locking and present measurements of the mesa beam tilt sensitivity
High Doses of Ursodeoxycholic Acid Up-Regulate the Expression of Placental Breast Cancer Resistance Protein in Patients Affected by Intrahepatic Cholestasis of Pregnancy
BACKGROUND:
Ursodeoxycholic acid (UDCA) administration in intrahepatic cholestasis of pregnancy (ICP) induces bile acids (BA) efflux from the foetal compartment, but the molecular basis of this transplacental transport is only partially defined.
AIM:
To determine if placental breast cancer resistance protein (BCRP), able to transport BA, is regulated by UDCA in ICP.
METHODS:
32 pregnant women with ICP (14 untreated, 34.9\ub15.17 years; 18 treated with UDCA--25 mg/Kg/day, 32.7\ub14.62 years,) and 12 healthy controls (33.4\ub13.32 years) agreed to participate in the study. Placentas were obtained at delivery and processed for membrane extraction. BCRP protein expression was evaluated by immunoblotting techniques and chemiluminescence quantified with a luminograph measuring emitted photons; mRNA expression with real time PCR. Statistical differences between groups were evaluated by ANOVA with Dunn's Multiple Comparison test.
RESULTS:
BCRP was expressed only on the apical membrane of the syncytiotrophoblast. A significant difference was observed among the three groups both for mRNA (ANOVA, p\u200a=\u200a0.0074) and protein (ANOVA, p<0.0001) expression. BCRP expression was similar in controls and in the untreated ICP group. UDCA induced a significant increase in placental BCRP mRNA and protein expression compared to controls (350.7\ub1106.3 vs 100\ub118.68% of controls, p<0.05 and 397.8\ub156.02 vs 100\ub111.44% of controls, p<0.001, respectively) and untreated ICP (90.29\ub117.59% of controls, p<0.05 and 155.0\ub113.87%, p<0.01).
CONCLUSION:
Our results confirm that BCRP is expressed only on the apical membrane of the syncytiotrophoblast and show that ICP treatment with high dose UDCA significantly upregulates placental BCRP expression favouring BA efflux from the foetal compartment
An overview on the natural enemies of Rhynchophorus palm weevils, with focus on R. ferrugineus.
Rhynchophorus palm weevils are large insects belonging to the family Dryophthoridae. All Rhynchophorus species are polyphagous and have a similar life history but some are major pests because of the serious economic damage they cause, in particular to several species of the family Arecaceae. Here we review the natural enemies of Rhynchophorus species in both their native and introduced regions of the world, to assess the possibility of biological control of this taxon. Moreover, particular attention is paid to the well-studied and harmful species Rhynchophorus ferrugineus, about which more information is available, and to its natural enemies in the Mediterranean region, because the impact of this pest in this recently colonized area is particularly remarkable and also the recent trend in species management is looking for indigenous natural enemies. More than 50 natural enemies have been reported to attack Rhynchophorus species, even if most of them are associated to R. ferrugineus (Olivier), highlighting the lack of information on the other species of the genus. Pros and cons of all the biological control agents are then discussed: among the considered organisms, fungi are noteworthy to be considered for inclusion in integrated pest management programs. Overall, our overview underlines the need to increase knowledge on natural enemies of all the species of the genus Rhynchophorus, to isolate more virulent strains and to determine the optimum conditions for the actions of the biocontrol agents
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