123 research outputs found

    Measurement of the Permanent Electric Dipole Moment of the 129^{129}Xe Atom

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    We report on a new measurement of the CP-violating permanent Electric Dipole Moment (EDM) of the neutral 129^{129}Xe atom. Our experimental approach is based on the detection of the free precession of co-located nuclear spin-polarized 3^3He and 129^{129}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, (−4.7±6.4)⋅10−28\left(-4.7\pm6.4\right)\cdot 10^{-28} ecm, is consistent with zero and is used to place a new upper limit on the 129^{129}Xe EDM: ∣dXe∣<1.5⋅10−27|d_\text{Xe}|<1.5 \cdot 10^{-27} 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

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    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

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    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 3^{3}He and 129^{129}Xe Magnetometers

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    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 3^3He and 129^{129}Xe atoms in a spherical cell inside a magnetic guiding field of about 400 nT using LTC_C 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∣∇⃗Bz∣=(5.6±0.4)|\vec{\nabla}B_z|=(5.6 \pm 0.4) 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

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    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

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    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 TruSightℱ 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

    Ensuring the Complex Environmental Management: Goals, Objectives and Regional Features

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    The article is aimed at developing theoretical and methodological approaches to identification of the basic components of the complex environmental management and ensuring their complementarity with the Goals of sustainable development for 2016–2030; definition of objectives and tasks of complex environmental management in the context of ensuring ecological-economic and social efficiency of natural resource potential development, as well as specification of the objectives of complex environmental management in the separately taken region. As a result of research the basic components of complex environmental management are defined. The main production-economic, socio-economic and ecological-economic goals of complex environmental management are characterized. It is proved that complex environmental management covers a set of industrial-technical and organizational-economic measures aimed at maximizing the benefit from economic development of natural resource potential at all phases of reproduced circuits without damaging the nature. Methods and technologies of complex environmental management are proposed
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