Spontaneous spin bifurcations and ferromagnetic phase transitions in a spinor exciton-polariton condensate

We observe a spontaneous parity breaking bifurcation to a ferromagnetic state in a spatially trapped exciton-polariton condensate. At a critical bifurcation density under nonresonant excitation, the whole condensate spontaneously magnetizes and randomly adopts one of two elliptically polarized (up to 95% circularly-polarized) states with opposite handedness of polarization. The magnetized condensate remains stable for many seconds at 5 K, but at higher temperatures it can flip from one magnetic orientation to another. We optically address these states and demonstrate the inversion of the magnetic state by resonantly injecting 100-fold weaker pulses of opposite spin. Theoretically, these phenomena can be well described as spontaneous symmetry breaking of the spin degree of freedom induced by different loss rates of the linear polarizations.This work was supported by Grants EPSRC No. EP/G060649/1, EU No. CLERMONT4 235114, EU No. INDEX 289968, Spanish MEC (MAT2008-01555), Greek GSRT ARISTEIA Apollo program and Fundación La Caixa, and Mexican CONACYT No. 251808. FP acknowledges financial support through an EPSRC doctoral prize fellowship at the University of Cambridge and a Schrödinger fellowship at the University of Oxford.This is the final version of the article. It first appeared from the American Physical Society via http://dx.doi.org/10.1103/PhysRevX.5.03100

Interrogating Nanojunctions Using Ultraconfined Acoustoplasmonic Coupling

Single nanoparticles are shown to develop a localized acoustic resonance, the bouncing mode, when placed on a substrate. If both substrate and nanoparticle are noble metals, plasmonic coupling of the nanoparticle to its image charges in the film induces tight light confinement in the nanogap. This yields ultrastrong “acoustoplasmonic” coupling with a figure of merit 7 orders of magnitude higher than conventional acousto-optic modulators. The plasmons thus act as a local vibrational probe of the contact geometry. A simple analytical mechanical model is found to describe the bouncing mode in terms of the nanoscale structure, allowing transient pump-probe spectroscopy to directly measure the contact area for individual nanoparticles.This work is supported by UK EPSRC grants EP/G060649/1, EP/L027151/1 and ERC grant LINASS 320503, as well as the Winton Programme for the Physics of Sustainability (FB, YdV-IR, JM), the Dr Manmohan Singh Scholarship from St John’s College (RC)

Familial tumoral calcinosis in two Chinese patients: a case series

Abstract Introduction Tumoral calcinosis is a rare and benign condition characterized by massive subcutaneous soft tissue deposits of calcium phosphate predominantly around large joints. Case presentation Familial tumoral calcinosis was present in two members of a Han Chinese family, namely, the son and daughter. The 14-year-old son had the first operation on his right sole of the foot at the age of six, and then experienced subsequent surgeries at a lesion in his right sole of the foot and left hip, respectively. The 16-year-old daughter underwent her first operation at the age of six in her left gluteal region, and subsequent surgeries were performed due to recurrence at the same lesion. Pathologic diagnoses of surgical specimens in both of the patients were reported as tumoral calcinosis. The laboratory results showed hyperphosphatemia with normal levels of serum calcium and alkaline phosphatase. Only surgical treatment was performed in both patients with satisfactory prognosis. Conclusion This is the first report of Chinese familial tumoral calcinosis. The etiopathogenisis and treatment are discussed.</p

Spin Order and Phase Transitions in Chains of Polariton Condensates

We demonstrate that multiply coupled spinor polariton condensates can be optically tuned through a sequence of spin-ordered phases by changing the coupling strength between nearest neighbors. For closed four-condensate chains these phases span from ferromagnetic (FM) to antiferromagnetic (AFM), separated by an unexpected crossover phase. This crossover phase is composed of alternating FM-AFM bonds. For larger eight-condensate chains, we show the critical role of spatial inhomogeneities and demonstrate a scheme to overcome them and prepare any desired spin state. Our observations thus demonstrate a fully controllable nonequilibrium spin lattice.We acknowledge Grants No. EPSRC EP/L027151/1, No. EU INDEX 289968, No. ERC “POLAFLOW” Starting Grant, ERC LINASS 320503, Spanish MEC (MAT2008- 01555), Mexican CONACYT 251808, Leverhulme Trust Grant No. VP1-2013-011 and Fundación La Caixa. H. S. and I. S. acknowledge support by the Research Fund of the University of Iceland, The Icelandic Research Fund, Grant No. 163082-051. T. L. was supported by the MOE AcRF Tier 1 Grant No. 2016-T1-001-084. P. S. acknowledges financial support from the Stavros Niarchos Foundation, “ARCHERS” project

Event-related potential correlates of sound organization: Early sensory and late cognitive effects

We tested whether incoming sounds are processed differently depending on how the preceding sound sequence has been interpreted by the brain. Sequences of a regularly repeating three-tone pattern, the perceived organization of which spontaneously switched back and forth between two alternative interpretations, were delivered to listeners. Occasionally, a regular tone was exchanged for a slightly or moderately lower one (deviants). The electroencephalogram (EEG) was recorded while listeners continuously marked their perception of the sound sequence. We found that for both the regular and the deviant tones, the early exogenous P1 and N1 amplitudes varied together with the perceived sound organization. Percept dependent effects on the late endogenous N2 and P3a amplitudes were only found for deviant tones. These results suggest that the perceived sound organization affects sound processing both by modulating what information is extracted from incoming sounds as well as by influencing how deviant sound events are evaluated for further processing

Strain-assisted optomechanical coupling of polariton condensate spin to a micromechanical resonator

We report spin and intensity coupling of an exciton-polariton condensate to the mechanical vibrations of a circular membrane microcavity. We optically drive the microcavity resonator at the lowest mechanical resonance frequency while creating an optically-trapped spin-polarized polariton condensate in different locations on the microcavity, and observe spin and intensity oscillations of the condensate at the vibration frequency of the resonator. Spin oscillations are induced by vibrational strain driving, whilst the modulation of the optical trap due to the displacement of the membrane causes intensity oscillations in the condensate emission. Our results demonstrate spin-phonon coupling in a macroscopically coherent condensate

Acral post-traumatic tumoral calcinosis in pregnancy: a case report

<p>Abstract</p> <p>Introduction</p> <p>Tumoral calcinosis is an uncommon disorder characterized by the development of calcified masses within the peri-articular soft tissues of large joints, but rarely occurs within the hand.</p> <p>Case presentation</p> <p>We present the case of a 31-year-old pregnant Indian woman with a three-month history of painful swelling within the tip of her right middle finger following a superficial laceration. She was otherwise well and had normal serum calcium and phosphate levels. Plain radiography demonstrated a dense, lobulated cluster of calcified nodules within the soft tissues of the volar pulp space, consistent with a diagnosis of tumoral calcinosis. This diagnosis was confirmed on the basis of the histopathological examination following surgical excision.</p> <p>Conclusion</p> <p>To the best of our knowledge, we present the only reported case of acral tumoral calcinosis within the finger, and the first description of its occurrence during pregnancy. We review the etiology, pathogenesis and treatment of tumoral calcinosis.</p

A Bacterial Ras-Like Small GTP-Binding Protein and Its Cognate GAP Establish a Dynamic Spatial Polarity Axis to Control Directed Motility

Directional control of bacterial motility is regulated by dynamic polarity inversions driven by pole-to-pole oscillation of a Ras family small G-protein and its associated GTPase-activating protein

Spontaneous spin bifurcations and ferromagnetic phase transitions in a spinor exciton-polariton condensate

We observe a spontaneous parity breaking bifurcation to a ferromagnetic state in a spatially trapped exciton-polariton condensate. At a critical bifurcation density under nonresonant excitation, the whole condensate spontaneously magnetizes and randomly adopts one of two elliptically polarized (up to 95% circularly polarized) states with opposite handedness of polarization. The magnetized condensate remains stable for many seconds at 5 K, but at higher temperatures, it can flip from one magnetic orientation to another. We optically address these states and demonstrate the inversion of the magnetic state by resonantly injecting 100- fold weaker pulses of opposite spin. Theoretically, these phenomena can be well described as spontaneous symmetry breaking of the spin degree of freedom induced by different loss rates of the linear polarizations.Publisher PDFPeer reviewe