Spin-orbit torques for current parallel and perpendicular to a domain wall

We report field- and current-induced domain wall (DW) depinning experiments in Ta/Co20Fe60B20/MgO nanowires through a Hall cross geometry. While purely field-induced depinning shows no angular dependence on in-plane fields, the effect of the current depends crucially on the internal DW structure, which we manipulate by an external magnetic in-plane field. We show for the first time depinning measurements for a current sent parallel to the DW and compare its depinning efficiency with the conventional case of current flowing perpendicularly to the DW. We find that the maximum efficiency is similar for both current directions within the error bars, which is in line with a dominating damping-like spin-orbit torque (SOT) and indicates that no large additional torques arise for currents parallel to the DW. Finally, we find a varying dependence of the maximum depinning efficiency angle for different DWs and pinning levels. This emphasizes the importance of our full angular scans compared to previously used measurements for just two field directions (parallel and perpendicular to the DW) and shows the sensitivity of the spin-orbit torque to the precise DW structure and pinning sites.Comment: 11 pages, 3 figure

Large Dzyaloshinskii-Moriya interaction induced by chemisorbed oxygen on a ferromagnet surface

The Dzyaloshinskii-Moriya interaction (DMI) is an antisymmetric exchange interaction that stabilizes chiral spin textures. It is induced by inversion symmetry breaking in noncentrosymmetric lattices or at interfaces. Recently, interfacial DMI has been found in magnetic layers adjacent to transition metals due to the spin-orbit coupling and at interfaces with graphene due to the Rashba effect. We report direct observation of strong DMI induced by chemisorption of oxygen on a ferromagnetic layer at room temperature. The sign of this DMI and its unexpectedly large magnitude-despite the low atomic number of oxygen-are derived by examining the oxygen coverage-dependent evolution of magnetic chirality. We find that DMI at the oxygen/ferromagnet interface is comparable to those at ferromagnet/transition metal interfaces; it has enabled direct tailoring of skyrmion's winding number at room temperature via oxygen chemisorption. This result extends the understanding of the DMI, opening up opportunities for the chemisorption-related design of spin-orbitronic devices

Prevalence and cardiovascular risk profile of chronic kidney disease in Italy: Results of the 2008-12 National Health Examination Survey

Background National surveys in countries outside Europe have reported a high prevalence (11-13%) of chronic kidney disease (CKD). Studies in Europe have provided a variable prevalence likely due to differences in study design, including age and extent of geographic areas, equation used to evaluate estimated glomerular filtration rate (eGFR) and CKD stages examined. Methods The 2008-12 National Health Examination Survey in Italy randomly extracted samples from the general population aged 35-79 years, stratified by age and gender, from the resident list of each Italian region (440 persons/1.5 million of residents). We estimated the prevalence of CKD by means of urinary albumin: creatinine ratio and eGFR (CKD-EPI equation-enzymatic assay of serum creatinine). Cardiovascular (CV) risk profile was also evaluated. Results Three thousand eight hundred and forty-eight men and 3704 women were examined. In the whole population, mean age was 57 ± 12 and 56 ± 12 years in men and women, respectively; hypertension was prevalent in men and women, respectively (56 and 43%) and the same held true for overweight (48 and 33%), obesity (26 and 27%), diabetes (14 and 9%) and smoking (21 and 18%), whereas CV disease was less frequent (9 and 6%). Overall, the prevalence of CKD (95% confidence interval) was 7.05% (6.48-7.65). Early stages constituted 59% of the CKD population [Stage G1-2 A2-3: 4.16% (3.71-4.61) and Stage G3-5: 2.89% (2.51-3.26)]. At multivariate regression analysis, age, obesity, hypertension, diabetes, CV disease and smoking were all independent correlates of CKD. Conclusions CKD has a relatively lower prevalence in Italy, in particular for advanced stages, when compared with similar national surveys outside Europe. This occurs despite older age and unfavourable CV risk profile of the whole population

人の行動の表現と認識に関する研究

In recent years, analyzing human motion and recognizing a performed action from a video sequence has become very important and has been a well-researched topic in the field of computer vision. The reason behind such attention is its diverse applications in different domains like robotics, human computer interaction, video surveillance, controller-free gaming, video indexing, mixed or virtual reality, intelligent environments, etc. There are a number of researches performed on motion recognition in the last few decades. The state of the art action recognition schemes generally use a holistic or a body part based approach to represent actions. Most of the methods provide reasonable recognition results, but they are sometimes not suitable for online or real time systems because of their complexity in action representation. In this thesis, we address this issue by proposing a novel action representation scheme.The proposed action descriptor is based on a basic idea that rather than detecting the exact body parts or analyzing each action sequence, human action can be represented by a distribution of local texture patterns extracted from spatiotemporal templates. In this study, we use a novel way of generating those templates. Motion History Image (MHI) merges an action sequence into a single template. However, having the problem in overwriting old information by a new one in the MHI, we use a variant named Directional MHI (DMHI) to diffuse the action sequence into four directional templates. And then we use the Local Binary Pattern (LBP) operator, but with a unique way, a rotated bit arranged LBP, to extract the local texture patterns from those DMHI templates. These spatiotemporal patterns form the basis of our action descriptor which is formulated into a concatenated block histogram to serve as a feature vector for action recognition. However, the extracted patterns by LBP tends to lose the temporal information in a DMHI, therefore we take a linear combination of the motion history information and texture information to represent an action sequence. We also use some variants of the proposed action representation that include the shape or pose information of the action silhouettes as a form of histogram.We show that, by effective classification of such histograms, i.e., action descriptor, robust human action recognition is possible. We demonstrate the effectiveness of the proposed method along with some variants of the method over two benchmark dataset; the Weizmann dataset and KTH dataset. Our results are directly comparable or superior to the results reported over these datasets. Higher recognition rates found in the experiment suggest that, compared to complex representation, the proposed simple and compact representation can achieve robust recognition of human activity for practical use. Besides the recognition rate, due to the simplicity of the proposed technique, it is also advantageous with respect to computational load.九州工業大学博士学位論文 学位記番号:工博甲第409号 学位授与年月日:平成28年3月25日1.Introduction|2.Action Representation and Recognition|3.Experiments and Results|4.Conclusion九州工業大学平成27年

Picosecond Spin Orbit Torque Switching

Reducing energy dissipation while increasing speed in computation and memory is a long-standing challenge for spintronics research. In the last 20 years, femtosecond lasers have emerged as a tool to control the magnetization in specific magnetic materials at the picosecond timescale. However, the use of ultrafast optics in integrated circuits and memories would require a major paradigm shift. An ultrafast electrical control of the magnetization is far preferable for integrated systems. Here we demonstrate reliable and deterministic control of the out-of-plane magnetization of a 1 nm-thick Co layer with single 6 ps-wide electrical pulses that induce spin-orbit torques on the magnetization. We can monitor the ultrafast magnetization dynamics due to the spin-orbit torques on sub-picosecond timescales, thus far accessible only by numerical simulations. Due to the short duration of our pulses, we enter a counter-intuitive regime of switching where heat dissipation assists the reversal. Moreover, we estimate a low energy cost to switch the magnetization, projecting to below 1fJ for a (20 nm)^3 cell. These experiments prove that spintronic phenomena can be exploited on picosecond time-scales for full magnetic control and should launch a new regime of ultrafast spin torque studies and applications.Comment: Includes article + supplementary information. Latest version uses full name of the first author. Nature Electronics (2020

Metabolic and cardiovascular effects of combined antiretroviral therapy in patients with HIV infection. Systematic review of literature

In HIV infected patients an increased incidence of cardiac events has been reported since the introduction of highly active antiretroviral therapy (HAART). Antiretroviral drugs’ regimens are, in fact, associated with several metabolic side effects, such as dyslipidemia, impaired glucose metabolism and abnormal body fat distribution, that increase cardiovascular risk of HIV subjects. In addition, HIV infection itself, the chronic inflammatory status and the frequent presence in this population of traditional risk factors contribute to an higher incidence of cardio and cerebrovascular events. In last years several studies showed the occurrence of carotid vascular impairment in patients treated with protease inhibitors (PI). Similarly the DAD Study reported an increase of 26% of the risk of myocardial infarction in patients on HAART and that this risk was independently associated with longer exposure to PI, after multivariate adjustments. A correct evaluation of the metabolic status before starting HAART and an adequate control of drugs-related metabolic abnormalities may reduce the incidence of cardiac events and still improve HIV patients prognosis. This review will focus on the metabolic effects of antiretroviral drugs and on the contribution of combination antiretroviral therapy on cardiovascular risk