Sub-millimetric ultra-low-field MRI detected in situ by a dressed atomic magnetometer

Magnetic Resonance Imaging (MRI) is universally acknowledged as an excellent tool to extract detailed spatial information with minimally invasive measurements. Efforts toward ultra-low-field (ULF) MRI are made to simplify the scanners and to reduce artefacts and incompatibilities. Optical Atomic Magnetometers (OAMs) are among the sensitive magnetic detectors eligible for ULF operation, however they are not compatible with the strong field gradients used in MRI. We show that a magnetic-dressing technique restores the OAMs operability despite the gradient, and we demonstrate sub-millimetric resolution MRI with a compact experimental setup based on an in situ detection. The proof-of-concept experiment produces unidimensional imaging of remotely magnetized samples with a dual sensor, but the approach is suited to be adapted for 3-D imaging of samples magnetized in loco. An extension to multi-sensor architectures is also possible.Comment: 5 pages, 3 figures, 36 refs, 3 pages supplemental material (+ 3refs). Accepted for publication in Appl.Phys.Let

Absorption resonance and large negative delay in Rb vapor with buffer gas

We observe a narrow, isolated, two-photon absorption resonance in Rb for large one-photon detuning in the presence of a buffer gas. In the absence of buffer gas, a standard Lambda configuration of two laser frequencies gives rise to electromagnetically induced transparency (EIT) for all values of one-photon detuning throughout the inhomogeneously (Doppler) broadened line. However, when a buffer gas is added and the one-photon detuning is comparable to or greater than the Doppler width, an absorption resonance appears instead of the usual EIT resonance. We also observe large negative group delay (~ -300 us for a Gaussian pulse propagating through the media with respect to a reference pulse not affected by the media), corresponding to a superluminal group velocity v_g= -c/(3.6x10^6)=-84 m/s.Comment: 4 pages, 5 figure

Cascade coherence transfer and magneto-optical resonances at 455 nm excitation of Cesium

We present and experimental and theoretical study of nonlinear magneto-optical resonances observed in the fluorescence to the ground state from the 7P_{3/2} state of cesium, which was populated directly by laser radiation at 455 nm, and from the 6P_{1/2} and 6P_{3/2} states, which were populated via cascade transitions that started from the 7P_{3/2} state and passed through various intermediate states. The laser-induced fluorescence (LIF) was observed as the magnetic field was scanned through zero. Signals were recorded for the two orthogonal, linearly polarized components of the LIF. We compared the measured signals with the results of calculations from a model that was based on the optical Bloch equations and averaged over the Doppler profile. This model was adapted from a model that had been developed for D_1 and D_2 excitation of alkali metal atoms. The calculations agree quite well with the measurements, especially when taking into account the fact that some experimental parameters were only estimated in the model.Comment: small changes to text of previous version; 12 pages, 8 figure

Spin randomization of light-induced desorbed Rb atoms

We present the first experimental observation of atomic spin randomization of Rb atoms released by light-induced atomic desorption (LIAD). A natural mixture of Rb atoms contained in paraffin and PDMS coated glass cells is irradiated by a free-running diode laser light tuned to the Rb D2 resonance line. The transmission spectrum of the Rb vapor is thus modified and shows a strong enhancement of the hyperfine optical pumping as the light intensity is increased and the laser-frequency scanning rate is decreased. The D2 line spectra are compared for two cases: without and with illumination of the walls of the cell by a UV lamp centered around the wavelength of 404 nm. A simple theoretical model based on the solution of the rate balance equations is introduced in order to analyze the experimental results

Silvicultural Efficiency of the Thinning Efficiency of Pinus sylvestris L. Plantation in the Dry Subzone of Northern Kazakhstan Steppes

Aim of study: Thinning efficiency after 18 years of cutting at the Scots pine (Pinus sylvestris L.) plantations, in the subzone of the dry grass steppe, were examined. Area of study: On 45-year-old Scots pine plantations on the territory of the state enterprise ZhasylAimak in Nur-Sultan city in the Northern Kazakhstan. Material and methods: The plantations were established by high density planting (13,300 seedlings/ha) of 2-year old seedlings. The planting was carried out on forest-suitable soils. To assess the silvicultural efficiency of the thinning in the plantation, the coefficient of growth tension or a complex estimated figure (CEF) was used. Main results: The research confirm that Scots pine plantations can be established in the subzone of dry fescue feather-grass steppe (Festuca valesiaca-Stipetum capillatae Sillinger 1930). The maximum silvicultural effect of thinning was achieved with three steps. In the 1st step of the thinning of the forest, 1015 years old trees are cut down. Trees with over-developed crown are also cut down. The 2nd step is made in 25-30 years with thinning intensity of 25% by stock. The 3rd step is made in 40-50 years in a uniform way. Highlights: In the harsh climatic conditions of Northern Kazakhstan steppe, deciduous trees and shrubs begin to age and die much earlier than the long-lived Scots pine

Modern management technologies

Розглянуто теоретичні аспекти та надано практичні рекомендації щодо запровадження сучасних технологій управління у практичній діяльності підприємств. Рекомендовано для фахівців з питань управління підприємствами, викладачів, аспірантів, магістрантів та студентів економічних спеціальностей вищих навчальних закладів.Theoretical aspects were considered and practical recommendations were given regarding the introduction of modern management technologies in the practical activities of enterprises. Recommended for business management specialists, teachers, graduate students, master's students and students of economic specialties of higher educational institutions