630 research outputs found
Evidence of Luttinger liquid behavior in one-dimensional dipolar quantum gases
The ground state and structure of a one-dimensional Bose gas with dipolar
repulsions is investigated at zero temperature by a combined Reptation Quantum
Monte Carlo (RQMC) and bosonization approach. A non trivial Luttinger-liquid
behavior emerges in a wide range of intermediate densities, evolving into a
Tonks-Girardeau gas at low density and into a classical quasi-ordered state at
high density. The density dependence of the Luttinger exponent is extracted
from the numerical data, providing analytical predictions for observable
quantities, such as the structure factor and the momentum distribution. We
discuss the accessibility of such predictions in current experiments with
ultracold atomic and molecular gases.Comment: 4 pages, 3 EPS figures, Revtex
Collective excitations of trapped one-dimensional dipolar quantum gases
We calculate the excitation modes of a 1D dipolar quantum gas confined in a
harmonic trap with frequency and predict how the frequency of the
breathing n=2 mode characterizes the interaction strength evolving from the
Tonks-Girardeau value to the quasi-ordered, super-strongly
interacting value . Our predictions are obtained
within a hydrodynamic Luttinger-Liquid theory after applying the Local Density
Approximation to the equation of state for the homogeneous dipolar gas, which
are in turn determined from Reptation Quantum Monte Carlo simulations. They are
shown to be in quite accurate agreement with the results of a sum-rule
approach. These effects can be observed in current experiments, revealing the
Luttinger-liquid nature of 1D dipolar Bose gases.Comment: 5 pages, 2 EPS figures, RevTeX
Nonmigrating semidiurnal tide over the Arctic determined from TIMED Doppler Interferometer wind observations
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94847/1/jgrd15899.pd
Reproductive disorders induced by Chlamydophila spp. infections in an italian mediterranean buffalo (bubalus bubalis) herd
The Italian Mediterranean Buffalo (Bubalus bubalis) has low fecundity and high incidence of abortion. Several studies have associated reproductive failure of water buffalo with viral infections but there is limited information on the role of chlamydial infections. To investigate the presence and the role of Chlamydiaceae in water buffalo a retrospective study was performed in a farm where, in the arch of 11 months, the pregnant heifers suffered an abortion rate of 36.8% in the 3rd and 5th month of pregnancy. Antibodies to Chlamydiaceae were detected in 57% of the aborted cows, while the rate of positivity was 0% in overtly healthy cows used as control. By a PCR assay 3 of 14 vaginal swabs from aborted animals tested positive for Chlamydophila agents and, additionally, 3 out of 7 aborted foetuses tested positive for Chlamydophila spp., with two being co-infections by Cp. abortus and Cp. pecorum and one being characterised as Cp. abortus. The presence of anti-Chlamydiaceae antibodies in 57% of the aborted animals and the detection of Chlamydophila agents in foetal organs and in vaginal swabs is consistent with the history of abortions (P<0.002) observed in the herd and may suggest a pathogenic role by Chlamydophila spp. in water buffalo
A comparison of optical and radar measurements of mesospheric winds and tides
Optical measurements of mesospheric winds by Fabry‐Perot spectrometers, FPSs, at Mawson, 67.6°S 62.9°E, and Davis, 68.6°S 78.0°E, Antarctica are compared with similar measurements obtained using a spaced‐antenna MF radar at Davis. The FPSs observed the OH emission. Different analysis procedures, used to determine the mean wind, and amplitude and phase of the semidiurnal tide, have been compared. At these latitudes the diurnal tide is weak and the semi‐diurnal tide, although highly variable in amplitude, is usually the dominant periodicity. When comparing the amplitude and phase of the semidiurnal tide good agreement is obtained between measurements by the two instruments
Correlation of Clinical Examination, MRI and Arthroscopy Findings in Menisco-Cruciate Injuries of the Knee: A Prospective Diagnostic Study
Background: The aim of this study was to examine the correlation of the clinical examination, MRI and arthroscopic findings in cruciate ligaments and meniscal injuries of knee and to evaluate the accuracy of clinical examination and MRI with the gold standard arthroscopy.
Methods: A prospective diagnostic double-blind study was conducted on 104 consecutive patients admitted to the outdoor/casualty with trauma to the knee complaining of knee pain/locking/ instability, from August 2012 to June 2014. All the patients were subjected to clinical examination, MRI scanning and diagnostic arthroscopy. Variables like sensitivity, specificity, positive predictive value, negative predictive value and accuracy of clinical examination and MRI against arthroscopy were evaluated.
Results: The sensitivity, specificity and accuracy of clinical examination for anterior cruciate ligament tears were 94.7%, 71.4% and 88.5% and for MRI were 94.7%, 78.6% and 90.4%, respectively; for posterior cruciate ligament tears 100%, 100% and 100% for clinical examination and for MRI 80%, 97.9% and 96.2%, respectively. These values for medial meniscus tears were 76.5%, 68.6% and 71.2% for clinical examination and 88.2%, 62.8% and 71.2% respectively for MRI. For lateral meniscus tears, 40%, 94.6% and 78.8% for clinical examination and 46.7%, 89.2% and 76.9% respectively for MRI.
Conclusions: A skillfully performed clinical examination establishes a diagnosis on which an arthroscopic procedure can be planned, reserving MRI scans for patients where the clinical examination fails to establish a diagnosis or cannot be performed. Decision to use MRI should be based on the criteria that it would confirm, expand the diagnosis or change diagnosis in such a way that alters the proposed treatment
PdZnAl Catalysts for the Reactions of Water-Gas-Shift, Methanol Steam Reforming, and Reverse-Water-Gas-Shift
Pd/ZnO/Al2O3 catalysts were studied for water-gas-shift (WGS), methanol steam reforming, and reverse-water-gas-shift (RWGS) reactions. WGS activity was found to be dependent on the Pd:Zn ratio with a maximum activity obtained at approximately 0.50, which was comparable to that of a commercial Pt-based catalyst. The catalyst stability was demonstrated for 100 hours time-on-stream at a temperature of 360ºC without evidence of metal sintering. WGS reaction rates were approximately 1st order with respect to CO concentration, and kinetic parameters were determined to be Ea = 58.3 kJ mol-1 and k0 = 6.1x107 min-1. During methanol steam reforming, the CO selectivities were observed to be lower than the calculated equilibrium values over a range of temperatures and steam/carbon ratios studied while the reaction rate constants were approximately of the same magnitude for both WGS and methanol steam reforming. These results indicate that although Pd/ZnO/Al2O3 are active WGS catalysts, WGS is not involved in methanol steam reforming. RWGS rate constants are on the order of about 20 times lower than that of methanol steam reforming, suggesting that RWGS reaction could be one of the sources for small amount of CO formation in methanol steam reforming
Strategies to reduce embryonic mortality in buffalo cows
The aim of the present study was to examine whether treatment with a GnRH agonist, hCG or P4 on Day 25 after AI increased P4 concentrations and reduced the incidence of embryonic mortality (EM) in pregnant buffaloes mated in mid-winter in a Mediterranean environment. The trial was carried out in two farms characterized, in previous years, by low (LEM Group), 153 buffaloes (DIM=150±7 days), and high (HEM Group), 284 buffaloes (DIM=163±5 days), incidence of embryo mortality. Animals were synchronized by Ovsynch-TAI Program and artificially inseminated. On day 25, pregnant buffaloes were randomly assigned to four groups: Control (no treatment), GnRH agonist (buserelin acetate, 12.6 μg), hCG (1500 IU) and P4 (341 mg of P4 i.m. every 4 days for three times). Progesterone (pg/ml) was determined in milk whey on Days 10, 20 and 25 after AI in all buffaloes and in Days 30 and 45 only in buffaloes pregnant on day 25 and assigned to four groups of treatment. Pregnancy diagnosis was undertaken on Day 45 by ultrasound. All treatments increased P4 milk whey and reduced embryonic mortality in buffalo cows bred in the farm characterized by high EM
embryonic mortality in buffalo naturally mated
The aim of this work was to evaluate the incidence of embryonic mortality in three different period of year in buffaloes naturally mated. The trial was carried out in a buffalo farm located in Caserta province between 2000-2006. In this period were registered natural insemination on 200 buffaloes. Pregnancy diagnosis was carried out on Day 30, confirmed on Day 45 and every 15th days until 90 days after natural mating. Buffaloes that were pregnant on Day 30 but not on Day 45 or Day 90 were considered to have undergone embryonic (EM) or fetal mortality (FM) respectively. EM and FM were 8.8% and 13.4% respectively throughout the experimental period. A high incidence (P<0.01) of FM was found in the transitional period (December-March) than in other months of the year. The incidence of embryonic mortality was significantly (P<0.01) higher between 28-60 days of gestation and lower after 71 day of gestation. The higher fetal mortality found in this study could be due the lower serum levels of progesterone normally found in transitional period in buffalo cows
Mediterranean river buffalo oxytocin-neurophysin I (OXT) gene: structure, promoter analysis and allele detection
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