Doppler shift oscillations in solar spicules

Consecutive height series of Ha spectra in solar limb spicules taken on the 53 cm coronagraph of Abastumani Astrophysical Observatory at the heights of 3800-8700 km above the photosphere have been analyzed. The aim is to observe oscillatory phenomena in spicules and consequently to trace wave propagations through the chromosphere. The Discrete Fourier Transform analysis of Ha Doppler shift time series constructed from the observed spectra at each height is used. Doppler velocities of solar limb spicules show oscillations with periods of 20-55 and 75-110 s. There is also the clear evidence of 3-min oscillations at the observed heights. The oscillations can be caused by wave propagations in thin magnetic flux tubes anchored in the photosphere. We suggest the granulation as a possible source for the wave excitation. Observed waves can be used as a tool for spicule seismology; the magnetic field strength in spicules at the height of about 6000 km above the photosphere is estimated as 12-15 G.Comment: 7 pages, 8 figures, accepted in A&

Nuclear spin diffusion in the semiconductor TlTaS3

We report on a 203Tl and 205Tl nuclear magnetic resonance study of the chain ternary semiconductor TlTaS3. We show that spin-lattice relaxation in this compound is driven by two contributions, namely by interactions of nuclear spins with thermally activated carriers and with localized electron spins. The latter mechanism dominates at lower temperature; at that, our measurements provide striking manifestation of the spin-diffusion-limited relaxation regime. The experimental data obtained allow us to estimate the spin diffusion coefficient.Comment: 15 pages, 5 figure

Observation of kink waves in solar spicules

Height series of H${\alpha}$ spectra in solar limb spicules obtained with the 53 cm coronagraph of the Abastumani Astrophysical Observatory are analyzed. Each height series covered 8 different heights beginning at 3800 km above the photosphere. The spatial difference between neighboring heights was 1$^{\prime \prime}$, consequently $\sim$ 3800 - 8700 km distance above the photosphere has been covered. The total time duration of each height series was 7 s. We found that nearly 20% of measured height series show a periodic spatial distribution of Doppler velocities. We suggest that this spatial periodicity in Doppler velocity is caused by propagating kink waves in spicules. The wave length is found to be $\sim$ 3500 km. However the wave length tends to be $\sim$ 1000 km at the photosphere due to the height variation of the kink speed. This probably indicates to a granular origin for the waves. The period of waves is estimated to be in the range of 35-70 s. These waves may carry photospheric energy into the corona, therefore can be of importance in coronal heating.Comment: 4 pages, 4 figures, Accepted in A&

Nuclear magnetic resonance probes for the Kondo scenario for the 0.7 feature in semiconductor quantum point contact devices

We propose a probe based on nuclear relaxation and Knight shift measurements for the Kondo scenario for the "0.7 feature" in semiconductor quantum point contact (QPC) devices. We show that the presence of a bound electron in the QPC would lead to a much higher rate of nuclear relaxation compared to nuclear relaxation through exchange of spin with conduction electrons. Furthermore, we show that the temperature dependence of this nuclear relaxation is very non-monotonic as opposed to the linear-T relaxation from coupling with conduction electrons. We present a qualitative analysis for the additional relaxation due to nuclear spin diffusion (NSD) and study the extent to which NSD affects the range of validity of our method. The conclusion is that nuclear relaxation, in combination with Knight shift measurements, can be used to verify whether the 0.7 feature is indeed due to the presence of a bound electron in the QPC.Comment: Published version. Appears in a Special Section on the 0.7 Feature and Interactions in One-Dimensional Systems. 16 page

Dynamic nuclear polarization and spin-diffusion in non-conducting solids

There has been much renewed interest in dynamic nuclear polarization (DNP), particularly in the context of solid state biomolecular NMR and more recently dissolution DNP techniques for liquids. This paper reviews the role of spin diffusion in polarizing nuclear spins and discusses the role of the spin diffusion barrier, before going on to discuss some recent results.Comment: submitted to Applied Magnetic Resonance. The article should appear in a special issue that is being published in connection with the DNP Symposium help in Nottingham in August 200

Light-induced nuclear quadrupolar relaxation in semiconductors

Light excitation of a semiconductor, known to dynamically-polarize the nuclear spins by hyperfine contact interaction with the photoelectrons, also generates an intrinsic nuclear depolarization mechanism. This novel relaxation process arises from the modulation of the nuclear quadrupolar Hamiltonian by photoelectron trapping and recombination at nearby localized states. For nuclei near shallow donors, the usual diffusion radius is replaced by a smaller, quadrupolar, radius. If the light excitation conditions correspond to partial donor occupation by photoelectrons, the nuclear magnetization and the nuclear field can be decreased by more than one order of magnitude

Выбор тактики хирургического лечения «острейшего» расслоения аорты I типа по De Bakey в условиях многопрофильного хирургического стационара

BACKGROUND Acute proximal aortic dissection (Stanford type A) remains the most common fatal pathology of the thoracic aorta. Despite the improvement of surgical technologies, hospital mortality after emergency surgical interventions is 17–25%, in complicated cases it can reach 80–90%.AIM OF STUDY Description of the perioperative treatment tactics adopted at the N.V. Sklifosovsky Research Institute for Emergency Medicine as well as the evolution of approaches that make it possible to obtain satisfactory hospital and long-term results in the treatment of aortic dissection.MATERIAL AND METHODS the study included 278 patients operated on from 2015 to 2021 in the acute stage of aortic dissection (less than 48 hours from the moment of manifestation of the disease). The operated patients were divided into two groups, depending on the presence of complicated forms: group A, 102 patients with uncomplicated course of the disease; group B, 176 patients with complicated course of the disease. Additionally, patients were divided depending on the level of distal reconstruction performed: group I, 83 patients, surgery was limited to prosthetics of the ascending aorta, without removing the clamp; group II, 137 patients who underwent hemi-arch surgery; group III, 58 patients, with distal reconstruction involving the aortic arch.RESULTS Total hospital mortality was 28.1%: 25.3% in group I, 29.1% in group II, 29.3% in group III. In the group of uncomplicated dissection, postoperative mortality was 18.6%, while in the group of complicated dissection it was 33.5%.CONCLUSION An integrated multidisciplinary approach with the formation of an “aortic team”, an individual approach to surgery, depending on the anatomy of the dissection and the clinical status of the patient, will improve the results of the treatment of acute aortic dissection, as the most severe and multiple organ pathology of the aorta.FINDING 1. Hospital mortality of complicated forms of dissection remains significantly higher — 33.5% versus 18.5% of uncomplicated course. 2. The most optimal method of distal reconstruction in patients with the peracute stage of dissection is an open anastomosis with the aorta using the “hemi-arch” technique. 3. If it is necessary to extend the surgical intervention on the aortic arch, a distal anastomosis in areas 0, 1, 2 with the possibility of a subsequent endovascular stage is the priority.ВВЕДЕНИЕ Острое проксимальное расслоение аорты (тип А по Stanford) остается самой частой смертельной патологией грудной аорты. Несмотря на совершенствование хирургических технологий, госпитальная летальность после экстренных оперативных вмешательств составляет 17–25%, в «осложненных» случаях она может достигать 80–90%.ЦЕЛЬ Описание периоперативной тактики лечения, принятой в НИИ скорой помощи им. Н. В. Склифосовского, а также эволюция подходов, дающих возможность получения удовлетворительных госпитальных и отдаленных результатов лечения расслоения аорты.МАТЕРИАЛ И МЕТОДЫ В исследование включены 278 пациентов, оперированных в период с 2015 по 2021 гг. в «острейшую» стадию расслоения аорты (менее 48 часов от момента манифестации заболевания). Оперированные больные были разделены на две группы, в зависимости от наличия «осложненных» форм: группа А — 102 пациента с «неосложненным» течением заболевания; группа В — 176 пациентов с «осложненным» течением заболевания. Дополнительно пациенты были разделены в зависимости от уровня выполненной дистальной реконструкции: группа I — 83 пациента, оперативное вмешательство ограничивалось протезированием восходящей аорты, без снятия зажима с аорты; группа II — 137 пациентов, которым была выполнена операция “hemi-arch”; группа III — 58 пациентов с расширением объема дистальной реконструкции на дугу аорты.РЕЗУЛЬТАТЫ Общая госпитальная летальность составила 28,1%: в I группе «зажима» — 25,3%, во II группе “hemi-arch” — 29,1%, в III группе «дуги» — 29,3%. В группе «неосложненного» расслоения послеоперационная летальность составила 18,6%, в то время как в группе «осложненного» — 33,5%.ЗАКЛЮЧЕНИЕ Комплексный мультидисциплинарный подход с формированием «аортальной команды», индивидуальный подход к хирургии в зависимости от анатомии расслоения и клинического статуса пациента позволят улучшить результаты лечения «острейшего» расслоения аорты, как наиболее тяжелой и полиорганной патологии аорты.ВЫВОДЫ 1. Госпитальная летальность «осложненных» форм расслоения остается значительно выше 33,5% против 18,5% «неосложненного» течения. 2. Наиболее оптимальным методом дистальной реконструкции у пациентов «сверхострой» стадии расслоения является наложение открытого анастомоза с аортой по методике “hemi-arch”. 3. При необходимости расширения хирургического вмешательства на дугу аорты, наложение дистального анастомоза в зонах 0, 1, 2 с возможностью последующего эндоваскулярного этапа является приоритетным направлением лечения

Ni-substituted sites and the effect on Cu electron spin dynamics of YBa2Cu{3-x}NixO{7-\delta}

We report Cu nuclear quadrupole resonance experiment on magnetic impurity Ni-substituted YBa$_2$Cu$_{3-x}$Ni$_x$O$_{7-\delta}$. The distribution of Ni-substituted sites and its effect on the Cu electron spin dynamics are investigated. Two samples with the same Ni concentration $x$=0.10 and nearly the same oxygen content but different $T_c$'s were prepared: One is an as-synthesized sample (7-$\delta$=6.93) in air ($T_c$$\approx 80 K$), and the other is a quenched one (7-$\delta$=6.92) in a reduced oxygen atmosphere ($T_c$$\approx 70 K$). The plane-site $^{63}$Cu(2) nuclear spin-lattice relaxation for the quenched sample was faster than that for the as-synthesized sample, in contrast to the $^{63}$Cu(1) relaxation that was faster for the as-synthesized sample. This indicates that the density of plane-site Ni(2) is higher in the quenched sample, contrary to the chain-site Ni(1) density which is lower in the quenched sample. From the analysis in terms of the Ni-induced nuclear spin-lattice relaxation, we suggest that the primary origin of suppression of $T_c$ is associated with nonmagnetic depairing effect of the plane-site Ni(2).Comment: 7 pages, 5 figure

Oscillations and waves in solar spicules

Since their discovery, spicules have attracted increased attention as energy/mass bridges between the dense and dynamic photosphere and the tenuous hot solar corona. Mechanical energy of photospheric random and coherent motions can be guided by magnetic field lines, spanning from the interior to the upper parts of the solar atmosphere, in the form of waves and oscillations. Since spicules are one of the most pronounced features of the chromosphere, the energy transport they participate in can be traced by the observations of their oscillatory motions. Oscillations in spicules have been observed for a long time. However the recent high-resolutions and high-cadence space and ground based facilities with superb spatial, temporal and spectral capacities brought new aspects in the research of spicule dynamics. Here we review the progress made in imaging and spectroscopic observations of waves and oscillations in spicules. The observations are accompanied by a discussion on theoretical modelling and interpretations of these oscillations. Finally, we embark on the recent developments made on the presence and role of Alfven and kink waves in spicules. We also address the extensive debate made on the Alfven versus kink waves in the context of the explanation of the observed transverse oscillations of spicule axes