Spin gating electrical current

We use an aluminium single electron transistor with a magnetic gate to directly quantify the chemical potential anisotropy of GaMnAs materials. Uniaxial and cubic contributions to the chemical potential anisotropy are determined from field rotation experiments. In performing magnetic field sweeps we observe additional isotropic magnetic field dependence of the chemical potential which shows a non-monotonic behavior. The observed effects are explained by calculations based on the $\mathbf{k}\cdot\mathbf{p}$ kinetic exchange model of ferromagnetism in GaMnAs. Our device inverts the conventional approach for constructing spin transistors: instead of spin-transport controlled by ordinary gates we spin-gate ordinary charge transport.Comment: 5 pages, 4 figure

Simultaneous OH-PLIF and schlieren imaging of flame acceleration in an obstacle-laden channel

Flame acceleration in stoichiometric H_2/O_2 at 12 and 25 kPa initial pressure in an obstacle-laden square cross-section channel was studied experimentally using planar laser-induced fluorescence imaging of hydroxyl radicals (OH-PLIF) and simultaneous high-speed schlieren imaging. Results were obtained resolving the explosion front structure as it develops immediately after ignition as a slow-flame to the eventual formation of a shock-flame complex in the fast-flame regime. The images provide a novel level of detail and allow for the determination of the effects of turbulence-flame and shock-flame interaction. In the slow-flame regime, vortex shedding off obstacle edges occurs over long time-scales, vortices are convected downstream and turbulent combustion takes place in the obstacle wakes. The fast-flame regime is marked by the presence of compression waves (and shock waves) which interact with the flame and cause macroscopic deformation of the flame and small-scale wrinkling due to Richtmyer-Meshkov instability. A quasi-steady fast-flame is characterized by the close proximity of the precursor shock and the turbulent flame. The flow-field that governs the flame shape is established impulsively by the precursor shock. Shock-flame interactions lead to flame front perturbations on both small and large scales. The OH-PLIF technique makes it possible to discern the flame front from other density interfaces that appear in the complex fast-flame structure observed in schlieren images and also eliminates the line-of-sight integration limitation

Reconfigurable Boolean Logic using Magnetic Single-Electron Transistors

We propose a novel hybrid single-electron device for reprogrammable low-power logic operations, the magnetic single-electron transistor (MSET). The device consists of an aluminium single-electron transistors with a GaMnAs magnetic back-gate. Changing between different logic gate functions is realized by reorienting the magnetic moments of the magnetic layer which induce a voltage shift on the Coulomb blockade oscillations of the MSET. We show that we can arbitrarily reprogram the function of the device from an n-type SET for in-plane magnetization of the GaMnAs layer to p-type SET for out-of-plane magnetization orientation. Moreover, we demonstrate a set of reprogrammable Boolean gates and its logical complement at the single device level. Finally, we propose two sets of reconfigurable binary gates using combinations of two MSETs in a pull-down network

Flame propagation across an obstacle: OH-PLIF and 2-D simulations with detailed chemistry

Flame propagation across a single obstacle inside a closed square channel is studied experimentally and numerically using a stoichiometric H_2/O_2 mixture at initial conditions 15 kPa and 300 K. The 50% blockage obstacle consists of a pair of fence-type obstacles mounted on the top and bottom walls of the channel. Direct optical visualization was performed using single-image measurement of the planar laser-induced fluorescence of the OH radical (OH-PLIF) and simultaneous high-speed schlieren video to study the flame topology and the flame tip velocity along the channel streamwise axis, respectively. The OH-PLIF images provide a novel level of detail and permit a thorough evaluation of the simulation accuracy. The flame tip accelerates to a peak velocity of 590 m/s just downstream of the obstacle followed by a deceleration and subsequent re-acceleration. The unburnt gas flow ahead of the flame is subsonic at all times. The flame does not show any signs of diffusive-thermal instability. Vortex–flame interactions in the recirculation zones downstream of the obstacle wrinkle the flame. The numerical simulations, based on solving the 2-D compressible reactive Navier–Stokes equations with detailed chemistry, predict the flame tip velocity accurately. However, differences in flame topology are observed, specifically, wrinkling is over-estimated. The over-prediction of flame wrinkling suggests a lower dissipation rate in the numerical simulations than in reality, which could be a consequence of neglecting the third channel dimension. Conditional means of the fuel consumption rate are similar to the consumption rates of 1-D unstretched laminar flames at all times. The increase in pressure during flame propagation causes an increase in fuel consumption rate which needs to be accounted for in simplified modeling approaches

Chromosome numbers for the Italian flora: 9

In this contribution, new chromosome data obtained on material collected in Italy are presented. It includes counts from six populations of three taxa within the genus Pulmonaria, two of which are endemic to Italy (P. vallarsae subsp. apennina and P. vallarsae subsp. vallarsae); the other is the widespread European P. officinalis. In addition, two counts from Potentilla detommasii and Stachys thirkei, two eastern Mediterranean species, are also reported

Role of inflammatory monocytes in adolescent metabolic syndrome

Metabolic syndrome (MetSyn) is a cluster of risk factors for cardiovascular disease and diabetes that affects 1 in 3 obese children. Inflammatory cytokines secreted from macrophages are thought to be partly responsible for the metabolic abnormalities associated with MetSyn. This study aimed to determine whether peripheral blood monocytes (macrophage precursors) from overweight individuals with MetSyn (Overwt-MetSyn) demonstrate enhanced activation of inflammatory signaling pathways when compared to metabolically normal overweight (Overwt-Healthy) or lean individuals. We conducted a cross sectional pilot study involving 24 adolescents (six boys and eighteen girls) recruited from the University of Massachusetts Boston and Worcester campuses. Six subjects were classified as Overwt-MetSyn using a modified definition proposed by the International Diabetes Federation. The Overwt-MetSyn group demonstrated an elevated expression of TLR2 and TLR4 in peripheral monocytes, and increased circulating levels of TNFa and IL6. Expression of TLR2 and TLR4 showed a positive correlation with circulating cytokines, and expression of TNFa correlated with waist circumference and BMI. Metabolic syndrome in adolescents is associated with increased activation of the TLR signaling pathway in monocytes. The knowledge gained from this study will advance our understanding of the contribution of monocytes to the pathophysiology of MetSyn

Rarity: Discovering rare cell populations from single-cell imaging data

MOTIVATION: Cell type identification plays an important role in the analysis and interpretation of single-cell data and can be carried out via supervised or unsupervised clustering approaches. Supervised methods are best suited where we can list all cell types and their respective marker genes a priori. While unsupervised clustering algorithms look for groups of cells with similar expression properties. This property permits the identification of both known and unknown cell populations, making unsupervised methods suitable for discovery. Success is dependent on the relative strength of the expression signature of each group as well as the number of cells. Rare cell types therefore present a particular challenge that are magnified when they are defined by differentially expressing a small number of genes. RESULTS: Typical unsupervised approaches fail to identify such rare sub-populations, and these cells tend to be absorbed into more prevalent cell types. In order to balance these competing demands, we have developed a novel statistical framework for unsupervised clustering, named Rarity, that enables the discovery process for rare cell types to be more robust, consistent and interpretable. We achieve this by devising a novel clustering method based on a Bayesian latent variable model in which we assign cells to inferred latent binary on/off expression profiles. This lets us achieve increased sensitivity to rare cell populations while also allowing us to control and interpret potential false positive discoveries. We systematically study the challenges associated with rare cell type identification and demonstrate the utility of Rarity on various IMC data sets. AVAILABILITY: Implementation of Rarity together with examples are available from the Github repository (https://github.com/kasparmartens/rarity). SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online

Superficial angiomyxoma in a pregnant cow

A 3-year-old, pregnant, Alpine Brown cow showed a rapidly growing, pedunculated, skin mass located at the umbilical region, reaching 8 kg in weight over a 3-month period after its initial detection. Six days after parturition, the mass was completely surgically excised. During the follow-up period, the cow remained in good health, without signs of recurrence, and showed increased milk production. Histological examination of the mass revealed a loose proliferation of spindle-shaped or stellate cells, immersed in an abundant myxoid matrix with admixed numerous thin-walled blood vessels. Immunohistochemically, the tumour cells were positive for vimentin, α-smooth muscle actin, and desmin. Gross and histopathological features were compatible with superficial angiomyxoma, a subtype of angiomyxoma rarely described in humans, but not in the veterinary literature. The tumour did not infiltrate into the surrounding tissues, and there was no post-excision recurrence after 3 months. The possibility of hormonal dependence of the tumour during pregnancy is discussed based on such findings in some human cases

Overview of the Low Complexity Enhancement Video Coding (LCEVC) Standard

The Low Complexity Enhancement Video Coding (LCEVC) specification is a recent standard approved by the ISO/IEC JTC 1/SC 29/WG04 (MPEG) Video Coding. The main goal of LCEVC is to provide a standalone toolset for the enhancement of any other existing codec. It works on top of other coding schemes, resulting in a multi-layer video coding technology, but unlike existing scalable video codecs, adds enhancement layers completely independent from the base video. The LCEVC technology takes as input the decoded video at lower resolution and adds up to two enhancement sub-layers of residuals encoded with specialized low-complexity coding tools, such as simple temporal prediction, frequency transform, quantization, and entropy encoding. This paper provides an overview of the main features of the LCEVC standard: high compression efficiency, low complexity, minimized requirements of memory and processing power

Intrinsic magnetic refrigeration of a single electron transistor

In this work, we show that aluminium doped with low concentrations of magnetic impurities can be used to fabricate quantum devices with intrinsic cooling capabilities. We fabricate single electron transistors made of aluminium doped with 2% Mn by using a standard multi angle evaporation technique and show that the quantity of metal used to fabricate the devices generates enough cooling power to achieve a drop of 160 mK in the electron temperature at the base temperature of our cryostat (300 mK). The cooling mechanism is based on the magneto-caloric effect from the diluted Mn moments