Reduction of energy cost of magnetization switching in a biaxial nanoparticle by use of internal dynamics

A solution to energy-efficient magnetization switching in a nanoparticle with biaxial anisotropy is presented. Optimal control paths minimizing the energy cost of magnetization reversal are calculated numerically as functions of the switching time and materials properties, and used to derive energy-efficient switching pulses of external magnetic field. Hard-axis anisotropy reduces the minimum energy cost of magnetization switching due to the internal torque in the desired switching direction. Analytical estimates quantifying this effect are obtained based on the perturbation theory. The optimal switching time providing a tradeoff between fast switching and energy efficiency is obtained. The energy cost of switching and the energy barrier between the stable states can be controlled independently in a biaxial nanomagnet. This provides a solution to the dilemma between energy-efficient writability and good thermal stability of magnetic memory elements.Comment: 13 pages, 10 figure

EVALUATION OF CONDITIONS CONCERNING THE DEVELOPMENT OF TOURISM. INVESTIGATION INTO THE BASIN OF THE PARSĘTA RIVER

DOI: 10.2478/v10089-008-0021-7 Available on-line at: http://www.bulletinofgeography.umk.pl http://versita.com/bgssThe article presents the results of multidimensional evaluation of conditions concerning the development of tourism in rural areas of Parsęta basin. For the purpose the synthetic measure has been applied in reference to 27 variables divided into two groups: suitable for tourism or investing. Having conducted the analysis of the selected variables, the investigated area was divided into three regions: the seaside at the North with very good conditions for the development of the touristic function as its core function, the central region, highly diversified with only moderate touristic capabilities, and finally the southern region, the lake district, with adequate features for the development of tourism

AI is a viable alternative to high throughput screening: a 318-target study

: High throughput screening (HTS) is routinely used to identify bioactive small molecules. This requires physical compounds, which limits coverage of accessible chemical space. Computational approaches combined with vast on-demand chemical libraries can access far greater chemical space, provided that the predictive accuracy is sufficient to identify useful molecules. Through the largest and most diverse virtual HTS campaign reported to date, comprising 318 individual projects, we demonstrate that our AtomNet® convolutional neural network successfully finds novel hits across every major therapeutic area and protein class. We address historical limitations of computational screening by demonstrating success for target proteins without known binders, high-quality X-ray crystal structures, or manual cherry-picking of compounds. We show that the molecules selected by the AtomNet® model are novel drug-like scaffolds rather than minor modifications to known bioactive compounds. Our empirical results suggest that computational methods can substantially replace HTS as the first step of small-molecule drug discovery

Optimal Control of Magnetization Reversal in a Monodomain Particle by Means of Applied Magnetic Field

A complete analytical solution to the optimal reversal of a macrospin with easy-axis anisotropy is presented. Optimal control path minimizing the energy cost of the reversal is identified and used to derive time-dependent direction and amplitude of the optimal switching field. The minimum energy cost of the reversal scales inversely with the switching time for fast switching, follows an exponential asymptotics for slow switching and reaches the lower limit proportional to the energy barrier between the target states and to the damping parameter at infinitely long switching time. For a given switching time, the energy cost is never smaller than that for a free macrospin. This limitation can be bypassed by adding a hard anisotropy axis which activates the internal torque in the desired switching direction, thereby significantly reducing the energy cost. Comparison between the calculated optimal control path and minimum energy path reveals that optimal control does not translate to the minimization of the energy barrier, but signifies effective use of the system's internal dynamics to aid the desired magnetic transition

Optimal protocol for spin-orbit torque switching of a perpendicular nanomagnet

It is demonstrated by means of the optimal control theory that the energy cost of the spin-orbit torque induced reversal of a nanomagnet with perpendicular anisotropy can be strongly reduced by proper shaping of both in-plane components of the current pulse. The time-dependence of the optimal switching pulse that minimizes the energy cost associated with Joule heating is derived analytically in terms of the required reversal time and material properties. The optimal reversal time providing a tradeoff between the switching speed and energy efficiency is obtained. A sweet-spot balance between the field-like and damping-like components of the spin-orbit torque is discovered; it permits for a particularly efficient switching by a down-chirped rotating current pulse whose duration does not need to be adjusted precisely.Comment: 6 pages, 3 figure

Intravascular lithotripsy for the treatment of stent underexpansion : the multicenter IVL-Dragon Registry

Background: Whereas the efficacy and safety of intravascular lithotripsy (IVL) have been confirmed in de novo calcified coronary lesions, little is known about its utility in treating stent underexpansion. This study aimed to investigate the impact of IVL in treating stent underexpansion. Methods and Results: Consecutive patients with stent underexpansion treated with IVL entered the multicenter IVL-Dragon Registry. The procedural success (primary efficacy endpoint) was defined as a relative stent expansion >80%. Thirty days device-oriented composite endpoint (DOCE) (defined as a composite of cardiac death, target lesion revascularization, or target vessel myocardial infarction) was the secondary endpoint. A total of 62 patients were enrolled. The primary efficacy endpoint was achieved in 72.6% of patients. Both stent underexpansion 58.5% (47.5–69.7) vs. 11.4% (5.8–20.7), p < 0.001, and the stenotic area 82.6% (72.4–90.8) vs. 21.5% (11.1–37.2), p < 0.001, measured by quantitative coronary angiography improved significantly after IVL. Intravascular imaging confirmed increased stent expansion following IVL from 37.5% (16.0–66.0) to 86.0% (69.2–90.7), p < 0.001, by optical coherence tomography and from 57.0% (31.5–77.2) to 89.0% (85.0–92.0), p = 0.002, by intravascular ultrasound. Secondary endpoint occurred in one (1.6%) patient caused by cardiac death. There was no target lesion revascularization or target vessel myocardial infarction during the 30-day follow-up. Conclusions: In this real-life, largest-to-date analysis of IVL use to manage underexpanded stent, IVL proved to be an effective and safe method for facilitating stent expansion and increasing luminal gain