Magnetic frustration and spontaneous rotational symmetry breaking in PdCrO2

In the triangular layered magnet PdCrO2 the intralayer magnetic interactions are strong, however the lattice structure frustrates interlayer interactions. In spite of this, long-range, 120$^\circ$ antiferromagnetic order condenses at $T_N = 38$~K. We show here through neutron scattering measurements under in-plane uniaxial stress and in-plane magnetic field that this occurs through a spontaneous lifting of the three-fold rotational symmetry of the nonmagnetic lattice, which relieves the interlayer frustration. We also show through resistivity measurements that uniaxial stress can suppress thermal magnetic disorder within the antiferromagnetic phase.Comment: 9 pages, 9 figure

Noninvasive Measurement of Aminolevulinic Acid-Induced Protoporphyrin IX Fluorescence Allowing Detection of Murine Glioma In Vivo

Aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) fluorescence is studied as a contrast agent for noninvasive detection of murine glioma, using the fluorescence-to-transmission ratio measured through the cranium. Signals measured prior to administration of ALA are very similar between control animals, 9L-GFP, and U251 tumor-bearing animals. However, 2 h after ALA administration, the PpIX signal from both tumor-bearing groups is significantly higher than the control group (9L-GFP group p-value=0.016, and U251 group p-value=0.004, relative to the control group). The variance in signal from the 9L-GFP group is much larger than either the control group or the U251 group, which is consistent with higher intrinsic PpIX fluorescence heterogeneity as seen in situ at ex vivo analysis. Decreasing the skin PpIX fluorescence via intentional photobleaching using red light (635 nm) is examined as a tool for increasing PpIX contrast between the tumor-bearing and control groups. The red light bleaching is found to increase the ability to accurately quantify PpIX fluorescence in vivo, but decreases the specificity of detection between tumor-bearing and nontumor-bearing groups

The use of the arts to encourage reflection in the dental professions — A commentary

Reflective practice is viewed internationally as an important activity within the dental professions and one which the General Dental Council expects to be part of all dental technician programmes in the United Kingdom (UK), irrespective of academic level. Informal discussions with colleagues delivering dental technology in UK higher education institutions agree that reflective practice is an important aspect of the curriculum, and learning is facilitated and assessed using various methods, for example, an online portfolio. Anecdotally, many of the current methods are shown to be ineffective, with up to fifty percent of students not meeting the reflective component. In the dental professions, consideration needs to be given to the use of creative methods to support reflective practice, in order to engage learners and contribute to the development of knowledge, skills and attitudes in this student group

Influenza A Virus Hemagglutinin Antibody Escape Promotes Neuraminidase Antigenic Variation and Drug Resistance

Drugs inhibiting the influenza A virus (IAV) neuraminidase (NA) are the cornerstone of anti-IAV chemotherapy and prophylaxis in man. Drug-resistant mutations in NA arise frequently in human isolates, limiting the therapeutic application of NA inhibitors. Here, we show that antibody-driven antigenic variation in one domain of the H1 hemagglutinin Sa site leads to compensatory mutations in NA, resulting in NA antigenic variation and acquisition of drug resistance. These findings indicate that influenza A virus resistance to NA inhibitors can potentially arise from antibody driven HA escape, confounding analysis of influenza NA evolution in nature

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Protoporphyrin IX Fluorescence Contrast in Invasive Glioblastomas is Linearly Correlated with Gd Enhanced Magnetic Resonance Image Contrast but has Higher Diagnostic Accuracy

The sensitivity and specificity of in vivo magnetic resonance (MR) imaging is compared with production of protoporphyrin IX (PpIX), determined ex vivo, in a diffusely infiltrating glioma. A human glioma transfected with green fluorescent protein, displaying diffuse, infiltrative growth, was implanted intracranially in athymic nude mice. Image contrast from corresponding regions of interest (ROIs) in in vivo MR and ex vivo fluorescence images was quantified. It was found that all tumor groups had statistically significant PpIX fluorescence contrast and that PpIX contrast demonstrated the best predictive power for tumor presence. Contrast from gadolinium enhanced T1-weighted (T1W+Gd) and absolute T2 images positively predicted the presence of a tumor, confirmed by the GFP positive (GFP+) and hematoxylin and eosin positive (H&E+) ROIs. However, only the absolute T2 images had predictive power from controls in ROIs that were GFP+ but H&E negative. Additionally, PpIX fluorescence and T1W+Gd image contrast were linearly correlated in both the GFP+ (r = 0.79, p\u3c1×10−8) and H&E+ (r = 0.74, p\u3c0.003) ROIs. The trace diffusion images did not have predictive power or significance from controls. This study indicates that gadolinium contrast enhanced MR images can predict the presence of diffuse tumors, but PpIX fluorescence is a better predictor regardless of tumor vascularity

Bilateral symmetry breaking in a nonlinear Fabry-Perot cavity exhibiting optical tristability

We show the existence of a region in the parameter space that defines the field dynamics in a Fabry-Perot cylindrical cavity, where three output stable stationary states of the light are possible for a given localized incident field. Two of these states do not preserve the bilateral (i.e. left-right) symmetry of the entire system. These broken-symmetry states are the high-transmission nonlinear modes of the system. We also discuss how to excite these states.Comment: 5 pages, 5 figure