107 research outputs found
Measurement of the Permanent Electric Dipole Moment of the Xe Atom
We report on a new measurement of the CP-violating permanent Electric Dipole
Moment (EDM) of the neutral Xe atom. Our experimental approach is based
on the detection of the free precession of co-located nuclear spin-polarized
He and Xe samples. The EDM measurement sensitivity benefits
strongly from long spin coherence times of several hours achieved in diluted
gases and homogeneous weak magnetic fields of about 400~nT. A finite EDM is
indicated by a change in the precession frequency, as an electric field is
periodically reversed with respect to the magnetic guiding field. Our result,
ecm, is consistent with zero and is
used to place a new upper limit on the Xe EDM: ecm (95% C.L.). We also discuss the implications of this result for
various CP-violating observables as they relate to theories of physics beyond
the standard model
Ultrasensitive 3He magnetometer for measurements of high magnetic fields
We describe a 3He magnetometer capable to measure high magnetic fields (B >
0.1 Tesla) with a relative accuracy of better than 10^-12. Our approach is
based on the measurement of the free induction decay of gaseous, nuclear spin
polarized 3He following a resonant radio frequency pulse excitation. The
measurement sensitivity can be attributed to the long coherent spin precession
time T2* being of order minutes which is achieved for spherical sample cells in
the regime of motional narrowing where the disturbing influence of field
inhomogeneities is strongly suppressed. The 3He gas is spin polarized in-situ
using a new, non-standard variant of the metastability exchange optical
pumping. We show that miniaturization helps to increase T2* further and that
the measurement sensitivity is not significantly affected by temporal field
fluctuations of order 10^-4.Comment: 27 pages, 7 figure
Test of Lorentz Symmetry by using a 3He/129Xe Co-Magnetometer
To test Lorentz symmetry we used a 3He/129Xe co-magnetometer. We will give a
short summary of our experimental setup and the results of our latest
measurements. We obtained preliminary results for the equatorial component of
the background field interacting with the spin of the bound neutron: b_n < 3.72
x 10^(-32) GeV (95 C.L.).Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28 - July 2, 201
Precise Measurement of Magnetic Field Gradients from Free Spin Precession Signals of He and Xe Magnetometers
We report on precise measurements of magnetic field gradients extracted from
transverse relaxation rates of precessing spin samples. The experimental
approach is based on the free precession of gaseous, nuclear spin polarized
He and Xe atoms in a spherical cell inside a magnetic guiding field
of about 400 nT using LT SQUIDs as low-noise magnetic flux detectors. The
transverse relaxation rates of both spin species are simultaneously monitored
as magnetic field gradients are varied. For transverse relaxation times
reaching 100 h, the residual longitudinal field gradient across the spin sample
could be deduced to be pT/cm. The method takes
advantage of the high signal-to-noise ratio with which the decaying spin
precession signal can be monitored that finally leads to the exceptional
accuracy to determine magnetic field gradients at the sub pT/cm scale
Limit on Lorentz and CPT violation of the bound Neutron Using a Free Precession 3He/129Xe co-magnetometer
We report on the search for Lorentz violating sidereal variations of the
frequency difference of co-located spin-species while the Earth and hence the
laboratory reference frame rotates with respect to a relic background field.
The co-magnetometer used is based on the detection of freely precessing nuclear
spins from polarized 3He and 129Xe gas samples using SQUIDs as low-noise
magnetic flux detectors. As result we can determine the limit for the
equatorial component of the background field interacting with the spin of the
bound neutron to be bn < 3.7 x 10^{-32} GeV (95 C.L.).Comment: 5 pages, 4 figure
Clinical Significance of Pathogenicity of Somatic Mutations in Oral Leukoplakia: a Prospective Observational Study
Background. The vast majority of malignant neoplasms of the oral mucosa refer to squamous cell carcinomas. The development of squamous cell carcinoma of the oral mucosa is often promoted by previous potentially malignant diseases, with oral leukoplakia dominating among them.Objective. To determine the clinical significance of the pathogenicity of somatic mutations in oral mucosal leukoplakia.Methods. The study material included 24 samples of abnormal epithelium of the oral mucosa from leukoplakia patients. QIAamp DNA FFPE Tissue Kit (Qiagen, Germany) was used for deoxyribonucleic acid (DNA) extraction from the samples. DNA sequencing was performed using IlluminaNextSeq 550 sequencer and TruSight™ Oncology 500 DNA Kit For Use with NextSeq (Illumina, USA). All DNA extractions from biological samples, preparation and sequencing of DNA libraries were performed step-by-step in strict accordance with the guidelines provided with the respective reagent kits. Bioinformatics analysis was carried out using specific software Illumina Base Space (Illumina, USA) and Galaxy Project (The Galaxy Community, a non-profit international project) according to current guidelines. The desired power of the study accounted for 90%. Two Proportions Z test was performed by means of The Sample Size Calculation of Statistica 12 (StatSoft, Inc.) with the set option “one-tailed hypothesis”, because it was initially assumed that pathogenic (oncogenic) genetic variants occur in the tissue of oral leukoplakia much more frequently than in the human reference genome used for sequence alignment.Results. The pathogenic somatic mutations in the TP53, KRAS, APC, NRAs and BRAF genes, identified in this study, alone or in combination, are highly likely (hazard ratio 3000-11000) to be associated with the development of oral mucosal leukoplakia and low-grade epithelial dysplasia. The multiplicity of pathogenic and likely pathogenic genetic variants associated with epithelial dysplasia, as well as the fact that a number of variants do not occur in all patients, suggests that the same histotype of oral mucosal dysplasia may develop under the influence of different mutations.Conclusion. The pathogenic and likely pathogenic variants of the TP53, KRAS, APC, NRAS and BRAF genes, identified in this study, alone or in combination, are highly likely (hazard ratio 3000–11000) to be associated with the development of leukoplakia and low-grade epithelial dysplasia
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