Correlated band theory of spin and orbital contributions to Dzyaloshinskii-Moriya interactions

A new approach for calculations of Dzyaloshinskii-Moriya interactions in molecules and crystals is proposed. It is based on the exact perturbation expansion of total energy of weak ferromagnets in the canting angle with the only assumption of local Hubbard-type interactions. This scheme leads to a simple and transparent analytical expression for Dzyaloshinskii-Moriya vector with a natural separation into spin and orbital contributions. The main problem was transferred to calculations of effective tight-binding parameters in the properly chosen basis including spin-orbit coupling. Test calculations for La$_2$CuO$_4$ give the value of canting angle in a good agreement with experimental data.Comment: 4 pages, 1 figur

First-principles modelling of magnetic excitations in Mn12

We have developed a fully microscopic theory of magnetic properties of the prototype molecular magnet Mn12. First, the intra-molecular magnetic properties have been studied by means of first-principles density functional-based methods, with local correlation effects being taken into account within the local density approximation plus U (LDA+U) approach. Using the magnetic force theorem, we have calculated the interatomic isotropic and anisotropic exchange interactions and full tensors of single-ion anisotropy for each Mn ion. Dzyaloshinskii-Moriya (DM) interaction parameters turned out to be unusually large, reflecting a low symmetry of magnetic pairs in molecules, in comparison with bulk crystals. Based on these results we predict a distortion of ferrimagnetic ordering due to DM interactions. Further, we use an exact diagonalization approach allowing to work with as large Hilbert space dimension as 10^8 without any particular symmetry (the case of the constructed magnetic model). Based on the computational results for the excitation spectrum, we propose a distinct interpretation of the experimental inelastic neutron scattering spectra.Comment: 8 pages, 2 figures. To appear in Physical Review

First-order transition between a small-gap semiconductor and a ferromagnetic metal in the isoelectronic alloys FeSi1−x_{1-x}Gex_x

The contrasting groundstates of isoelectronic and isostructural FeSi and FeGe can be explained within an extended local density approximation scheme (LDA+U) by an appropriate choice of the onsite Coulomb repulsion, $U$ on the Fe-sites. A minimal two-band model with interband interactions allows us to obtain a phase diagram for the alloys FeSi$_{1-x}$Ge$_{x}$. Treating the model in a mean field approximation, gives a first order transition between a small-gap semiconductor and a ferromagnetic metal as a function of magnetic field, temperature, and concentration, $x$. Unusually the transition from metal to insulator is driven by broadening, not narrowing, the bands and it is the metallic state that shows magnetic order.Comment: 4 pages, 5 figure

Balancing patient-centered and safe pain care for non-surgical inpatients: clinical and managerial perspectives

Background: Hospitals and clinicians aim to deliver care that is safe. Simultaneously, they are ensuring that care is patient-centered, meaning that it is respectful of patients’ values, preferences, and experiences. However, little is known about delivering care in cases where these goals may not align. For example, hospitals and clinicians are facing the daunting challenge of balancing safe and patient-centered pain care for nonsurgical patients, due to lack of comprehensive care guidelines and complexity of this patient population. Methods: To gather clinical and managerial perspectives on the importance, feasibility, and strategies used to balance patient-centered care (PCC) and safe pain care for nonsurgical inpatients, we conducted in-depth, semi-structured interviews with hospitalists (n=10), registered nurses (n=10), and health care managers (n=10) from one healthcare system in the Midwestern United States. We systematically examined transcribed interviews and identified major themes using a thematic analysis approach. Results: Participants acknowledged the importance of balancing PCC and safe pain care. They envisioned this balance as a continuum, with certain patients for whom it is easier (e.g., opioid-naïve patient with a fracture), versus more difficult (e.g., patient with opioid use disorder). Participants also reported several strategies they use to balance PCC and safe pain care, including offering alternatives to opioids, setting realistic pain goals and expectations, and using a team approach. Conclusions: Clinicians and health care managers use various strategies to balance PCC and safe pain care for nonsurgical patients. Future studies should examine the effectiveness of these strategies on patient outcomes

Morphophysiological peculiarities of productivity formation in columnar apple varieties

Received: December 30th, 2021 ; Accepted: February 22nd, 2022 ; Published: March 4th, 2022 ; Correspondence: [email protected] of generative buds is one of the most important biological processes of plant transition from vegetative to generative state. This process is key to the problem of creating regular fruit-bearing and early-fruiting plantations. The article provides information on the organogenesis of buds in plants of columnar apple varieties in the Forest-Steppe of Ukraine, which allows establishing the features of this process in complex fruit formations of different ages, and the levels of their productivity and longevity. Research to study the organogenesis of different-age fruit formations of columnar apple varieties was conducted in the northern part of the Forest-Steppe of Ukraine during 2016–2020. The efficiency of realization the plants biological potential of all studied columnar apple varieties at III–IV and V–IX stages of organogenesis was high: the largest number of buds from their total number differentiated into generative on trees varieties ‘Sparta’, ‘President’, ‘Bilosnizhka’, ‘Valuta’ and ‘Tantsivnytsia’ (37–51%), the smallest in ‘Favoryt’ and ‘Bolero’. The biggest number of flowers per one potentially generative bud was formed by plants of ‘Tantsivnytsia’ and ‘Bilosnizhka’ varieties. The lowest level of ovarian loss during the X stage of organogenesis was observed on plants of ‘Valuta’, ‘President’, and ‘Tantsivnytsia’ varieties (41–49%), and the highest - in ‘Favoryt’ variety (up to 83%). More effective realization of potential productivity at the XI stage of organogenesis occurred in plants of ‘President’, ‘Valuta’ and ‘Tantsivnytsia’ varieties; their trees on one potentially generative bud formed - 0.27–0.38 fruits. The coefficient of determination indicates that the influence of meteorological conditions of the year on the passage of III–IV stages of organogenesis is 46%; V–IX stages - 42%; Stage X - 17%; Stage XI - 24%

Clinical perspectives on hospitals’ role in the opioid epidemic

Policymakers, legislators, and clinicians have raised concerns that hospital-based clinicians may be incentivized to inappropriately prescribe and administer opioids when addressing pain care needs of their patients, thus potentially contributing to the ongoing opioid epidemic in the United States. Given the need to involve all healthcare settings, including hospitals, in joint efforts to curb the opioid epidemic, it is essential to understand if clinicians perceive hospitals as contributors to the problem. Therefore, we examined clinical perspectives on the role of hospitals in the opioid epidemic

Recurrent Network Classifier for Ultrafast Skyrmion Dynamics

By using supervised learning, we train a recurrent neural network to recognize and classify ultrafast magnetization processes that are realized in two-dimensional nanosystems with Dzyaloshinskii-Moriya interactions. Our focus is on different types of skyrmion dynamics driven by ultrafast magnetic pulses. Each process is represented as a sequence of sorted magnetization vectors that are inputted into the network. The trained network can perform an accurate classification of the skyrmionic processes at zero temperature over a wide range of magnetic pulse widths and damping factors. The network performance is also demonstrated on different types of unseen data, including finite-temperature processes. Our approach can be easily adapted for creating an autonomous control system on skyrmion dynamics for experiments or data-storage devices. © 2019 American Physical Society.We thank Yaroslav Kvashnin and Anders Bergman for fruitful discussions and technical assistance with the uppasd package. This work is supported by the Russian Science Foundation Grant No. 18-12-00185