7,081 research outputs found
Whole-body MRI for preventive health screening:A systematic review of the literature
Background The yield of whole-body MRI for preventive health screening is currently not completely clear. Purpose To systematically review the prevalence of whole-body MRI findings in asymptomatic subjects. Study Type Systematic review and meta-analysis. Subjects MEDLINE and Embase were searched for original studies reporting whole-body MRI findings in asymptomatic adults without known disease, syndrome, or genetic mutation. Twelve studies, comprising 5373 asymptomatic subjects, were included. Field Strength/Sequence 1.5T or 3.0T, whole-body MRI. Assessment The whole-body MRI literature findings were extracted and reviewed by two radiologists in consensus for designation as either critical or indeterminate incidental finding. Statistical Tests Data were pooled using a random effects model on the assumption that most subjects had 5-year) verification of negative findings. Only one study reported false-negative findings, with a proportion of 2.0%. Data Conclusion Prevalence of critical and indeterminate incidental whole-body MRI findings in asymptomatic subjects is overall substantial and with variability dependent to some degree on the protocol. Verification data are lacking. The proportion of false-positive findings appears to be substantial. Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:1489-1503
Preparation of Zirconium Powder Through ZrCl4 Bubbling in Mg-MgCl2 Bath
An alternative process has been studied for zirconium production through chemical reaction between ZrCl4 bubbles and magnesium melt floating on molten MgCl2 salt. The preparation of pure zirconium in the form of powder was successfully accomplished by cleaning process consisting of washing with distilled water and pickling with hydrochloric acid solution. The purity of zirconium powder increased with dense concentration of hydrochloric acid solution and longer pickling time by removing residual magnesium, MgCl2 and other impurities except for zirconium. The sufficiently high level of purity was achieved by pickling for 6 hours using 3 mass% of hydrochloric acid solution. It was noteworthy that purity of zirconium powder was deteriorated with the formation of intermetallic compounds when alumina or iron was used for apparatus material. Meanwhile, a sound quality without any intermetallic compound and high purity were achieved when MgO material was used. It was found that there were no significant differences in purity and morphology of zirconium powder depending on reaction temperature. However, mean particle size was increased by increasing reaction temperature.110Ysciescopu
From Molecular Cores to Planet-forming Disks with SIRTF
The SIRTF mission and the Legacy programs will provide coherent data bases
for extra-galactic and Galactic science that will rapidly become available to
researchers through a public archive. The capabilities of SIRTF and the six
legacy programs are described briefly. Then the cores to disks (c2d) program is
described in more detail. The c2d program will use all three SIRTF instruments
(IRAC, MIPS, and IRS) to observe sources from molecular cores to protoplanetary
disks, with a wide range of cloud masses, stellar masses, and star-forming
environments. The SIRTF data will stimulate many follow-up studies, both with
SIRTF and with other instruments.Comment: 6 pages, from Fourth Cologne-Bonn-Zermatt-Symposium, The Dense
Interstellar Matter in Galaxie
Application of the DRA method to the calculation of the four-loop QED-type tadpoles
We apply the DRA method to the calculation of the four-loop `QED-type'
tadpoles. For arbitrary space-time dimensionality D the results have the form
of multiple convergent sums. We use these results to obtain the
epsilon-expansion of the integrals around D=3 and D=4.Comment: References added, some typos corrected. Results unchange
Successful outcome of a pregnancy in a woman with advanced cirrhosis due to hepatitis B surface antigenemia, delta super-infection and hepatitis C co-infection: a case report
Pregnancy in women with advanced liver disease is rare. In this paper we described the case of a successful pregnancy in a young woman with advanced cirrhosis due to hepatitis B surface antigenemia, hepatitis delta super-infection and Hepatitis C co-infection. A brief review of the medical literature on pregnancy in women with cirrhosis is also presented
Transmit Power Minimization for MIMO Systems of Exponential Average BER with Fixed Outage Probability
This document is the Accepted Manuscript version of the following article: Dian-Wu Yue, and Yichuang Sun, ‘Transmit Power Minimization for MIMO Systems of Exponential Average BER with Fixed Outage Probability’, Wireless Personal Communications, Vol. 90 (4): 1951-1970, first available online on 20 June 2016. Under embargo. Embargo end date: 20 June 2017. The final publication is available at Springer via https://link.springer.com/article/10.1007%2Fs11277-016-3432-4This paper is concerned with a wireless multiple-antenna system operating in multiple-input multiple-output (MIMO) fading channels with channel state information being known at both transmitter and receiver. By spatiotemporal subchannel selection and power control, it aims to minimize the average transmit power (ATP) of the MIMO system while achieving an exponential type of average bit error rate (BER) for each data stream. Under the constraints on each subchannel that individual outage probability and average BER are given, based on a traditional upper bound and a dynamic upper bound of Q function, two closed-form ATP expressions are derived, respectively, which can result in two different power allocation schemes. Numerical results are provided to validate the theoretical analysis, and show that the power allocation scheme with the dynamic upper bound can achieve more power savings than the one with the traditional upper bound.Peer reviewe
Pseudogap temperature as a Widom line in doped Mott insulators
The pseudogap refers to an enigmatic state of matter with unusual physical
properties found below a characteristic temperature in hole-doped
high-temperature superconductors. Determining is critical for
understanding this state. Here we study the simplest model of correlated
electron systems, the Hubbard model, with cluster dynamical mean-field theory
to find out whether the pseudogap can occur solely because of strong coupling
physics and short nonlocal correlations. We find that the pseudogap
characteristic temperature is a sharp crossover between different
dynamical regimes along a line of thermodynamic anomalies that appears above a
first-order phase transition, the Widom line. The Widom line emanating from the
critical endpoint of a first-order transition is thus the organizing principle
for the pseudogap phase diagram of the cuprates. No additional broken symmetry
is necessary to explain the phenomenon. Broken symmetry states appear in the
pseudogap and not the other way around.Comment: 6 pages, 4 figures and supplementary information; published versio
- …