Synthesis and magnetic characterization of co-axial Ge1-xMnx/a-Si heterostructures

A method for synthesizing Ge1–xMnx/a-Si core–shell nanowires (x = 0.3(1)–1.0(2)) using a supercritical fluid deposition technique, with a homogeneous distribution of manganese along the entire lengths of the crystalline Ge cores but not in the a-Si shells, is reported. Investigations into the magnetic properties of the heterostructured nanowires revealed a significant influence of the amorphous Si shell covering the surface of the core Ge0.997Mn0.003 nanowires compared to pristine Ge0.997Mn0.003 nanowires with no a-Si coating. The magnetic data revealed diminished values of both the remanence and the saturation magnetization for pristine Mn-doped Ge nanowires at higher temperatures when compared to the Ge1–xMnx/a-Si core–shell nanowires, whereas both parameters increased as the temperature dropped down to 5 K. Differences in the temperature-dependent evolution of the coercivity were observed in the magnetically harder core–shell nanowires compared to the pristine Ge0.997Mn0.003 nanowires, showing a drop of 26% at 5 K vs room temperature compared to a drop of 66% for the pristine nanowires. The low dopant concentration (0.3(1)%) of Mn in the core–shell nanowires, combined with the observed ferromagnetic properties, suggests a combination of hole-mediated exchange and confinement processes are responsible for the observed properties. Our observations show the importance of a protective layer in covering the oxidation-sensitive dilute magnetic semiconductor nanowires

V-Shaped Domain Wall Probes for Calibrated Magnetic Force Microscopy

Magnetic force microscopy (MFM) qualitatively resolves stray magnetic fields, but its fundamental flaws include limited quantitative analysis and difficulties in measuring samples with heterogeneous magnetic areas. We propose a custom made domain wall probe (DWP) with a V-shaped magnetic nanostructure on one face of a non-magnetic probe, which behaves as a low moment probe with high coercivity to reduce magnetic switching in the presence of strong stray fields. The performance of the DWP is compared against commercial standard and low moment probes with different approaches to quantify resolution from striped domain structures of a thin reference film. The three probes are calibrated by acquiring the tip-transfer function (TTF) from a Fourier transform approach. The calculated TTF is used to predict the MFM response from a permalloy nanostructure and compared to experimental results

A reduced-reference perceptual image and video quality metric based on edge preservation

In image and video compression and transmission, it is important to rely on an objective image/video quality metric which accurately represents the subjective quality of processed images and video sequences. In some scenarios, it is also important to evaluate the quality of the received video sequence with minimal reference to the transmitted one. For instance, for quality improvement of video transmission through closed-loop optimisation, the video quality measure can be evaluated at the receiver and provided as feedback information to the system controller. The original image/video sequence-prior to compression and transmission-is not usually available at the receiver side, and it is important to rely at the receiver side on an objective video quality metric that does not need reference or needs minimal reference to the original video sequence. The observation that the human eye is very sensitive to edge and contour information of an image underpins the proposal of our reduced reference (RR) quality metric, which compares edge information between the distorted and the original image. Results highlight that the metric correlates well with subjective observations, also in comparison with commonly used full-reference metrics and with a state-of-the-art RR metric. © 2012 Martini et al

Neglected Tropical Diseases. The Place of Ivermectin in the Elimination Programs

The World Health Organization identifies as neglected nineteen tropical diseases with bacterial, viral and parasitic etiology, of which two are ophthalmological. These diseases affect over one billion people worldwide, especially communities in developing countries, with limited access to healthcare, clean water, and sewerage. These include: trachoma, onchocerciasis (river blindness), leprosy, leishmaniasis, schistosomiasis, foodborne trematode infections, dracunculiasis, Chagas disease, Human African trypanosomiasis, lymphatic filariasis (elephantiasis), cysticercosis, echinococcosis, soil-transmitted helminthiases, Dengue, rabies, yaws, scabies, Buruli ulcer, mycetoma, chromoblastomycosis and other deep mycoses. The global effort in fighting neglected tropical diseases is one of the biggest initiatives in the field of public health. On the 28th of January 2021 the World Health Organization initiated a new ten-year plan for the eradication of neglected tropical diseases. It aims to lower the mortality, new disability cases and suffering of more than one billion people

Calibration of multi-layered probes with low/high magnetic moments

We present a comprehensive method for visualisation and quantification of the magnetic stray field of magnetic force microscopy (MFM) probes, applied to the particular case of custom-made multi-layered probes with controllable high/low magnetic moment states. The probes consist of two decoupled magnetic layers separated by a non-magnetic interlayer, which results in four stable magnetic states: ±ferromagnetic (FM) and ±antiferromagnetic (A-FM). Direct visualisation of the stray field surrounding the probe apex using electron holography convincingly demonstrates a striking difference in the spatial distribution and strength of the magnetic flux in FM and A-FM states. In situ MFM studies of reference samples are used to determine the probe switching fields and spatial resolution. Furthermore, quantitative values of the probe magnetic moments are obtained by determining their real space tip transfer function (RSTTF). We also map the local Hall voltage in graphene Hall nanosensors induced by the probes in different states. The measured transport properties of nanosensors and RSTTF outcomes are introduced as an input in a numerical model of Hall devices to verify the probe magnetic moments. The modelling results fully match the experimental measurements, outlining an all-inclusive method for the calibration of complex magnetic probes with a controllable low/high magnetic moment

Geek Culture As a New ‘Image’ of Contemporary Culture

The aim of this article is to present the theoretical grounding of geek culture as a unique contemporary phenomenon, based on structural-functional, evolutionary, and systemic methodology within the overarching culturological approach. We verify the meaning of such concepts as ‘geek’, ‘geek community’, and ‘geek culture’; explore the role and the characteristics of geek culture as a supra-subculture; analyze its global universal features and the specifics of its Russian variant; describe a unique characteristic of geek culture as a self-organizing system; and highlight the dualistic features of geek culture as a ‘marker’ of contemporary social processes.     Keywords: geek, geek culture, geek community, supra-subculture, consumer subculture, mass subculture, youth subculture, counter-culture, mainstrea

Anesthetics for magnetic resonance studies in rodents (Systematic review of experimental results)

The choice of anesthetics for magnetic resonance imaging in rodents is a difficult and important task. Experiments carried out on small laboratory animals are analyzed in this review. Heart rate, mean arterial pressure, and respiratory rate measured during the experiment under anesthesia of various types are described. Since anesthetics affect the physiological state of animals, they indirectly influence the results of investigation. Therefore, prior to the start of experiment, a literary search has to be carried out in order to choose a method of anesthesia least affecting the parameters studied