High-efficiency optical pumping of nuclear polarization in a GaAs quantum well

The dynamic polarization of nuclear spins by photoexcited electrons is studied in a high quality GaAs/AlGaAs quantum well. We find a surprisingly high efficiency of the spin transfer from the electrons to the nuclei as reflected by a maximum nuclear field of 0.9 T in a tilted external magnetic field of 1 T strength only. This high efficiency is due to a low leakage of spin out of the polarized nuclear system, because mechanisms of spin relaxation other than the hyperfine interaction are strongly suppressed, leading to a long nuclear relaxation time of up to 1000 s. A key ingredient to that end is the low impurity concentration inside the heterostructure, while the electrostatic potential from charged impurities in the surrounding barriers becomes screened through illumination by which the spin relaxation time is increased compared to keeping the system in the dark. This finding indicates a strategy for obtaining high nuclear spin polarization as required for long-lasting carrier spin coherence.Comment: 6 pages, 4 figure

All-optical dc nanotesla magnetometry using silicon vacancy fine structure in isotopically purified silicon carbide

We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-$^{28}$SiC) and find extra terms in the spin Hamiltonian, originated from the trigonal pyramidal symmetry of this spin-3/2 color center. These terms give rise to additional spin transitions, which are otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity of 87 nT Hz$^{-1/2}$ within a volume of $3 \times 10^{-7}$ mm$^{3}$ at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radiofrequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3 mm$^{3}$ the projection noise limit is below 100 fT Hz$^{-1/2}$.Comment: 12 pages, 6 figures; additional experimental data and an extended theoretical analysis are added in the second versio

Nonlinear Bogolyubov-Valatin transformations and quaternions

In introducing second quantization for fermions, Jordan and Wigner (1927/1928) observed that the algebra of a single pair of fermion creation and annihilation operators in quantum mechanics is closely related to the algebra of quaternions H. For the first time, here we exploit this fact to study nonlinear Bogolyubov-Valatin transformations (canonical transformations for fermions) for a single fermionic mode. By means of these transformations, a class of fermionic Hamiltonians in an external field is related to the standard Fermi oscillator.Comment: 6 pages REVTEX (v3: two paragraphs appended, minor stylistic changes, eq. (39) corrected, references [10]-[14], [36], [37], [41], [67]-[69] added; v4: few extensions, references [62], [63] added, final version to be published in J. Phys. A: Math. Gen.

The main indicators of functional diagnostics service in the Udmurt Republic

One of the main methods of diagnosis are functional diagnostic methods. The modern development of medical science and practice requires health care organizers to constantly monitor changes in this area. A great contribution to this is made by scientific research. The aim of the work was to analyze the activity of the functional diagnostics service of the Udmurt Republic for 2014-2016.the paper used the annual reports of the Federal statistical observation and annual reports on the state of health of citizens of the Udmurt Republic for the analyzed period. The results established the stability of the functional diagnostics service in the Udmurt Republic. There was an increase in the volume of work performed by specialists of functional diagnostics of the Udmurt Republic. In General, the diagnosis of the population of the region was carried out at the level of outpatient service. The provision of medical personnel in the functional diagnostics service of the Udmurt Republic showed their deficit. This was accompanied by a large proportion of compatibility of specialists with higher medical education. The electrocardiography method prevailed in the share of all functional diagnostic methods. The results can be used by the organizers of health of the Udmurt Republic to make the necessary organizational and management decisions.Функциональные методы исследования, согласно принятым современным рекомендациям, являются основой для установления правильного диагноза. Это требует от организаторов здравоохранения перманентного динамического мониторирования службы функциональной диагностики и, на основании выявленных изменений, принятия своевременных организационно-управленческих решений для их улучшения. Целью работы было – провести анализ деятельности службы функциональной диагностики Удмуртской республики за 2014-2016гг. В работе использовались годовые отчеты федерального статистического наблюдения и годовые отчеты о состоянии здоровья граждан Удмуртской республики за анализируемый период. Исследование показало, что работа службы функциональной диагностики Удмуртской республики оценивалась как стабильная. общий объем выполненной работы специалистами функциональной диагностики ежегодно увеличивался, основная часть исследований осуществлялась на амбулаторно-поликлиническом уровне. В кадровом составе службы функциональной диагностики в Удмуртской республике наблюдался дефицит специалистов и, как следствие, высокий процент врачебного совместительства (при укомплектованности в 40,7% - занятость 95,6%). Наибольшее число исследований приходилось на сердечно-сосудистую систему. Самым распространенным методом в регионе был метод электрокардиографии. Полученные нами результаты могут быть использованы организаторами здравоохранения Удмуртской республики для принятия необходимых организационно-управленческих решений

The impact of olfactory and gustatory perception on metabolic homeostasis in obese patients

Obesity is currently a major global public health problem. As a result, in recent decades there has been a growing interest in studying the impact of this disease on the functioning of the central nervous system. One of the least understood aspects is the impact that obesity has on sensory systems.The olfactory and gustatory systems are closely related to various vital functions, such as the nocifensors activation, the stimulation of digestive reflexes. In addition, these sensory systems are known to play an important role in the mechanisms of food consumption through the regulation of appetite and satiety, influencing food choice and, therefore, they are involved in the development of obesity. A number of clinical studies have shown that obese patients are more likely to suffer from hyposmia compared to lean people of the same age.The reasons why this relationship exists remain largely unclear. The aim of this review is to assess the available data on this topic and to identify new promising areas for further research. The review was conducted in the PubMed databases for 2017–2023

Possibilities of radionuclide visualization of HER2/neu-positive breast cancer using a radiopharmaceutical based on recombinant targeting molecules DARPin9_29

Epidermal growth receptor HER2/neu is still of great interest, the overexpression of which is most often observed in patients with breast cancer and accounts for 15–20 % of cases. Present methods of HER2/neu determination have a number of significant drawbacks. In recent years, alternative framework proteins are used for the targeted radionuclide imaging. Molecules of DARPin (Design Ankyrin Repeat Protein) are one of representatives of scaffolds. Material and methods. The study included 4 breast cancer patients (T1-2N0-1M0) who were not receiving systemic therapy at the time of the study: in 2 patients, HER2/neu overexpression was noted, in 2 patients – not detected. HER2/neu status was determined using an immunohistochemical method and a FISH assay. At the preclinical stage, radiopharmaceutical 99mTc-DARPin9_29 was injected intravenously to all patients, «WholeBody» scintigraphy and single-photon emission computed tomography were performed 2 hours after injection. Results. The distribution of radiopharmaceuticals in organs 2 hours after injection revealed the greatest accumulation in the liver and kidneys. In studying of tumor/background indicator it was revealed that values of the studied parameter in patients with overexpression of HER2 receptors are more than 3 times higher than the values in the subgroup of patients with negative expression of this marker. Conclusion. According to the results of preliminary studies, the 99mTc-DARPin9_29 demonstrated significant differences between tumors with and without HER2/neu overexpression