Super-harmonic injection locking of nano-contact spin-torque vortex oscillators

Super-harmonic injection locking of single nano-contact (NC) spin-torque vortex oscillators (STVOs) subject to a small microwave current has been explored. Frequency locking was observed up to the fourth harmonic of the STVO fundamental frequency $f_{0}$ in microwave magneto-electronic measurements. The large frequency tunability of the STVO with respect to $f_{0}$ allowed the device to be locked to multiple sub-harmonics of the microwave frequency $f_{RF}$, or to the same sub-harmonic over a wide range of $f_{RF}$ by tuning the DC current. In general, analysis of the locking range, linewidth, and amplitude showed that the locking efficiency decreased as the harmonic number increased, as expected for harmonic synchronization of a non-linear oscillator. Time-resolved scanning Kerr microscopy (TRSKM) revealed significant differences in the spatial character of the magnetization dynamics of states locked to the fundamental and harmonic frequencies, suggesting significant differences in the core trajectories within the same device. Super-harmonic injection locking of a NC-STVO may open up possibilities for devices such as nanoscale frequency dividers, while differences in the core trajectory may allow mutual synchronisation to be achieved in multi-oscillator networks by tuning the spatial character of the dynamics within shared magnetic layers.Comment: 21 pages, 8 figure

Direct observation of magnetization dynamics generated by nano-contact spin-torque vortex oscillators

Time-resolved scanning Kerr microscopy has been used to directly image the magnetization dynamics of nano-contact (NC) spin-torque vortex oscillators (STVOs) when phase-locked to an injected microwave (RF) current. The Kerr images reveal free layer magnetization dynamics that extend outside the NC footprint, where they cannot be detected electrically, but which are crucial to phase-lock STVOs that share common magnetic layers. For a single NC, dynamics were observed not only when the STVO frequency was fully locked to that of the RF current, but also for a partially locked state characterized by periodic changes in the core trajectory at the RF frequency. For a pair of NCs, images reveal the spatial character of dynamics that electrical measurements show to have enhanced amplitude and reduced linewidth. Insight gained from these images may improve understanding of the conditions required for mutual phase-locking of multiple STVOs, and hence enhanced microwave power emission.Comment: 10 pages, 3 figure

What can we learn from multi-objective meta-optimization of Evolutionary Algorithms in continuous domains?

Properly configuring Evolutionary Algorithms (EAs) is a challenging task made difficult by many different details that affect EAs' performance, such as the properties of the fitness function, time and computational constraints, and many others. EAs' meta-optimization methods, in which a metaheuristic is used to tune the parameters of another (lower-level) metaheuristic which optimizes a given target function, most often rely on the optimization of a single property of the lower-level method. In this paper, we show that by using a multi-objective genetic algorithm to tune an EA, it is possible not only to find good parameter sets considering more objectives at the same time but also to derive generalizable results which can provide guidelines for designing EA-based applications. In particular, we present a general framework for multi-objective meta-optimization, to show that "going multi-objective" allows one to generate configurations that, besides optimally fitting an EA to a given problem, also perform well on previously unseen ones

Risk Factors Sharp Injury Among Healthcare Workers in Sleman State Hospital YOGYAKARTA Province Indonesia

Background : The sharp injury is the most burden problem among healthcare workers. The prevalence slightly increased as consequences spreading blood-borne pathogen. Some researchers had found several variables associated sharp injury among medical workers in the hospital. Objective : The objective of this research was to identify variables that significantly correlated sharp injury among healthcare workers in Sleman State Hospital, Yogyakarta Province, Indonesia. Methods : A cross-sectional study was conducted with total sampling as the method to collect respondents. Total population including a doctor, nurse, midwife, laboratory assistant has been selected based on inclusion criteria such as length of work more than one year and approved to be respondents, amounted 133 samples research. The analysis used chisquare for bivariate and logistic regression test for multivariate. Results : There were nine variables had identified that were age, gender, the level of education, the length of work, salary, occupation, employment status, body mass index, and the marital status. According chi-square analysis obtained gender, the level of education, salary, occupation, employment status and body mass index which were significantly correlated sharp injury (p-value > 0.05). Therefore, only two variables based on logistic regression had statistically related sharp injury. Those variables were salary <1.388.000 IDR (p-value 0.008, aOR 0.135, CI 0.031- 10.594) and abnormal body mass index (p-value 0.000, aOR 6.218, CI 2.552-15.147). Conclusion : In summary, there were two variables had correlated sharp injury among healthcare workers in Sleman state hospital Yogyakarta province, Indonesia; salary and body mass index

Ethno-botanical survey of medicinal plants used traditionally in the treatment of mental disorders in Kano, Nigeria

Purpose: To identify medicinal plants used by traditional medicine practitioners to treat mental disorders within Kano metropolis, Nigeria.Methods: A semi-structured questionnaire was administered. It was made up of demographic information (Section A), description of the medicinal plants (Section B), and the professional experience of the respondents (Section C). The data generated were recorded, processed and analyzed.Results: 255 responses were collected from 127 respondents. Among the participants, 101 (79 %) were male and 26 (21 %) were female. The age groups less than 31 years were 22 (17 %), 31 - 40 years were 29 (23 %), 41 - 50 years were 45 (36 %), and above 51 years were 31 (24 %). The sources of knowledge identified include ancestral (83 %), ancestral/training (9 %), training (6 %), and divination (2 %). Out of the total responses, fifty (50) different medicinal plants with various claims in the treatment of mental disorders were reported. The most commonly stated medicinal plants were Securidaca longepedunculata (8.6 %), Jatropha curcas (7.5 %), Solanum aethiopicum (7.1 %), Artemesia annua (6.7 %), Terminalia macroptera (6.3 %), Aristolochia albida (5.9 %), Nigella sativa (5.5 %), Andira inermis (5.5 %), Calotropis procera (5.1 %), and Burkea africana (4.7 %).Conclusion: This survey revealed fifty medicinal plants used traditionally in the treatment of mental disorders within Kano metropolis

WISE colours and star-formation in the host galaxies of radio-loud narrow-line Seyfert 1

We investigate the mid-infrared properties of the largest (42 objects) sample of radio-loud narrow-line Seyfert 1 (RL NLS1) collected to date, using data from the Wide-field Infrared Survey Explorer (WISE). We analyse the mid-IR colours of these objects and compare them to what is expected from different combinations of AGN and galaxy templates. We find that, in general, the host-galaxy emission gives an importan contribution to the observed mid-IR flux in particular at the longest wavelengths (W3, at 12micron, and W4, at 22micron). In about half of the sources (22 objects) we observe a very red mid-IR colour (W4-W3>2.5) that can be explained only using a starburst galaxy template (M82). Using the 22micron luminosities, corrected for the AGN contribution, we have then estimated the star-formation rate for 20 of these "red" RL NLS1, finding values ranging from 10 to 500 Msun/y. For the RL NLS1 showing bluer colours, instead, we cannot exclude the presence of a star-forming host galaxy although, on average, we expect a lower star-formation rate. Studying the radio (1.4GHz) to mid-IR (22micron) flux ratios of the RL NLS1 in the sample we found that in ~10 objects the star-forming activity could represent the most important component also at radio frequencies, in addition (or in alternative) to the relativistic jet. We conclude that both the mid-IR and the radio emission of RL NLS1 are a mixture of different components, including the relativistic jet, the dusty torus and an intense star-forming activity.Comment: Accepted for publication in MNRAS, 11 pages, 7 figures, 2 table

Analysis of Physics Learning Instruments Based Problem Based Learning Model

This study aims to produce a device design appropriate learning with problem-based learning model and analyze whether learning instrument developed can improve student learning outcomes. This development research done on a limited test by using a class by using research methods 4D development. 4D method is used as a method for designing a learning device to the stages define, design, and develope, while disseminate not done for a limited test. The development of learning instrument assessed by a team of experts, small group, and then the field test. Improved learning outcomes using the NGain. The result of the design of the learning device developed by researchers in accordance with input from a team of experts, small groups and field testing of the categories eligible to use. There is an increase in student learning outcomes after using problem-based learning instrument with the N-Gain in the medium category

Pengembangan Sensor Kompas Digital dan Sensor Akselerasi untuk Memantau Gerakan Tanah pada Bidang Longsor dalam Upaya Pengurangan Risiko Bencana

Tanah longsor merupakan salah satu bencana yang sering terjadi di Indonesia. Sebaran bencana longsor sangat luas karena lebih dari 60% wilayah daratan di Indonesia merupakan daerah rawan longsor. Fakta menunjukkan bahwa masyarakat sering menjadi korban akibat belum optimalnya fungsi sistem peringatan dini bencana tanah longsor. Salah satu upaya pengurangan risiko bencana tersebut adalah dengan menerapkan teknologi sensor elektronis dalam sistem peringatan dini tanah longsor. Dalam paper ini pergerakan tanah dijadikan fokus utama dalam pemantauan, dimana Perubahan posisi permukaan tanah menjelang longsor adalah parameter utama yang akan dipantau yang mengacu pada [creep theory]. Peranti yang dikembangkan dalam paper ini adalah alat yang dapat memantau Perubahan kemiringan tanah pada sumbu X dan sumbu Y menggunakan sensor akselerasi. Peranti ini akan memberikan peringatan dini berupa suara sirine jika terjadi Perubahan kemiringan tanah yang telah melampaui batas aman. Fitur tambahan pada peranti ini adalah sensor kompas digital yang dapat memantau arah diagonal dari Perubahan kemiringan tanah akibat tanah longsor. Pemantauan arah diagonal bertujuan untuk memprediksi arah longsoran tanah untuk menentukan jalur evakuasi yang aman. Hasil sistem yang dikembangkan mempunyai resolusi sebesar 1° dengan jangkauan pengukuran antara 0°-85° pada sumbu X dan sumbu Y. Sedangkan pemantauan arah diagonal mempunyai resolusi sebesar 1° dengan jangkauan pengukuran antara 0°-359°. Spesifikasi tersebut sudah memenuhi kriteria untuk membangun sistem peringatan dini tanah longsor