We use coupled micropillars etched out of a semiconductor microcavity to engineer a spin-orbit Hamiltonian for photons and polaritons in a microstructure. The coupling between the spin and orbital ...momentum arises from the polarization-dependent confinement and tunneling of photons between adjacent micropillars arranged in the form of a hexagonal photonic molecule. It results in polariton eigenstates with distinct polarization patterns, which are revealed in photoluminescence experiments in the regime of polariton condensation. Thanks to the strong polariton nonlinearities, our system provides a photonic workbench for the quantum simulation of the interplay between interactions and spin-orbit effects, particularly when extended to two-dimensional lattices.
Background
Metformin is widely used for treating women with polycystic ovary syndrome (PCOS), and many patients with PCOS who are infertile receive gonadotrophins while being treated with metformin.
...Objectives
To assess the effects of metformin administration in infertile patients with PCOS who receive gonadotrophins for in vitro fertilisation (IVF) and intracytoplasmic sperm injection (ICSI) cycles.
Search strategy
We searched international scientific databases, websites for the registration of trials, and bibliographies of retrieved articles, books, and review articles up to August 2012.
Selection criteria
Randomised controlled trials (RCTs).
Data collection and analysis
Authors independently reviewed and extracted the data.
Main results
Ten RCTs (with a total of 845 women with PCOS) were included in the final analysis. Metformin administration in IVF/ICSI cycles had no effect on the rates of pregnancy (OR 1.20, 95% CI 0.90–1.61) and live birth (OR 1.69, 95% CI 0.85–3.34). No effect of metformin dose, metformin pretreatment duration, and stopping time of metformin administration was observed on these reproductive end points. Metformin administration reduced the risk of ovarian hyperstimulation syndrome (OHSS; OR 0.27, 95% CI 0.16–0.46) and of miscarriage (OR 0.50, 95% CI 0.30–0.83), while increased that of implantation (OR 1.42, 95% CI 1.24–2.75).
Author's conclusions
In infertile patients with PCOS treated with gonadotrophins for IVF/ICSI cycles, metformin exerts no clinical effect on rates of pregnancy or live birth, but it reduces the risk of OHSS, and improves the rates of miscarriage and implantation. Further RCTs are needed to assess the reproductive effect of metformin in young well‐selected patients with PCOS and specific phenotypes and features.
In quantum magnets, magnetic moments fluctuate heavily and are strongly entangled with each other, a fundamental distinction from classical magnetism. Here, with inelastic neutron scattering ...measurements, we probe the spin correlations of the honeycomb lattice quantum magnet YbCl
. A linear spin wave theory with a single Heisenberg interaction on the honeycomb lattice, including both transverse and longitudinal channels of the neutron response, reproduces all of the key features in the spectrum. In particular, we identify a Van Hove singularity, a clearly observable sharp feature within a continuum response. The demonstration of such a Van Hove singularity in a two-magnon continuum is important as a confirmation of broadly held notions of continua in quantum magnetism and additionally because analogous features in two-spinon continua could be used to distinguish quantum spin liquids from merely disordered systems. These results establish YbCl
as a benchmark material for quantum magnetism on the honeycomb lattice.
The coupling of two macroscopic quantum states through a tunnel barrier gives rise to Josephson phenomena1 such as Rabi oscillations2, the a.c. and d.c. effects3, or macroscopic self-trapping, ...depending on whether tunnelling or interactions dominate4. Nonlinear Josephson physics was rst observed in superuid helium5 and atomic condensates6,7, but it has remained inaccessible in photonic systems because it requires large photonphoton interactions. Here we report on the observation of nonlinear Josephson oscillations of two coupled polariton condensates conned in a photonic molecule formed by two overlapping micropillars etched in a semiconductor microcavity8. At low densities we observe coherent oscillations of particles tunnelling between the two sites.
Abstract
The ability to represent information using an antiferromagnetic material is attractive for future antiferromagnetic spintronic devices. Previous studies have focussed on the utilization of ...antiferromagnetic materials with biaxial magnetic anisotropy for electrical manipulation. A practical realization of these antiferromagnetic devices is limited by the requirement of material-specific constraints. Here, we demonstrate current-induced switching in a polycrystalline PtMn/Pt metallic heterostructure. A comparison of electrical transport measurements in PtMn with and without the Pt layer, corroborated by x-ray imaging, reveals reversible switching of the thermally-stable antiferromagnetic Néel vector by spin-orbit torques. The presented results demonstrate the potential of polycrystalline metals for antiferromagnetic spintronics.
A quantum fluid passing an obstacle behaves differently from a classical one. When the flow is slow enough, the quantum gas enters a superfluid regime, and neither whirlpools nor waves form around ...the obstacle. For higher flow velocities, it has been predicted that the perturbation induced by the defect gives rise to the turbulent emission of quantized vortices and to the nucleation of solitons. Using an interacting Bose gas of exciton-polaritons in a semiconductor microcavity, we report the transition from superfluidity to the hydrodynamic formation of oblique dark solitons and vortex streets in the wake of a potential barrier. The direct observation of these topological excitations provides key information on the mechanisms of superflow and shows the potential of polariton condensates for quantum turbulence studies.
Melatonin, a pineal gland synthesized neurohormone is known as a multifunctioning pleiotropic agent which has a wide range of neuroprotective role in manifold age-related neurodegenerative disorders ...especially Alzheimer’s diseases (AD). AD is a devastating neurodegenerative disorder and common form of dementia which is defined by abnormal and excessive accumulation of several toxic peptides including amyloid β (Aβ) plaques and neurofibrillary tangles (NFTs). The Alzheimer’s dementia relates to atrophic changes in the brain resulting in loss of memory, cognitive dysfunction, and impairments of the synapses. Aging, circadian disruption, Aβ accumulation, and tau hyperphosphorylation are the utmost risk factor regarding AD pathology. To date, there is no exact treatment against AD progression. In this regard, melatonin plays a crucial role for the inhibition of circadian disruption by controlling clock genes and also attenuates Aβ accumulation and tau hyperphosphorylation by regulating glycogen synthase kinase-3 (GSK3) and cyclin-dependent kinase-5 (CDK5) signaling pathway. In this review, we highlight the possible mechanism of AD etiology and how melatonin influences neurogenesis by attenuating circadian disruption, Aβ formation, as well as tau hyperphosphorylation. Furthermore, we also find out and summarize the neuroprotective roles of melatonin by the blockage of Aβ production, Aβ oligomerization and fibrillation, tau hyperphosphorylation, synaptic dysfunction, oxidative stress, and neuronal death during AD progression.
Measurements of the transverse Hall resistance are widely used to investigate electron transport, magnetization phenomena, and topological quantum states. Owing to the difficulty of probing transient ...changes of the transverse resistance, the vast majority of Hall effect experiments are carried out in stationary conditions using either dc or ac. Here we present an approach to perform time-resolved measurements of the transient Hall resistance during current-pulse injection with sub-nanosecond temporal resolution. We apply this technique to investigate in real-time the magnetization reversal caused by spin-orbit torques in ferrimagnetic GdFeCo dots. Single-shot Hall effect measurements show that the current-induced switching of GdFeCo is widely distributed in time and characterized by significant activation delays, which limit the total switching speed despite the high domain-wall velocity typical of ferrimagnets. Our method applies to a broad range of current-induced phenomena and can be combined with non-electrical excitations to perform pump-probe Hall effect measurements.
Summary
Porcine circovirus type 3 (PCV3) was recently proposed as a new porcine circovirus. It has been described by researchers in the USA and China and associated with porcine dermatitis and ...nephropathy syndrome, reproductive failure and systemic inflammation disease. The study reports the occurrence of the new virus in Italy. PCV3 was detected in the tissues of foetuses and stillborn piglets coming from two farms located in the Po Valley. The genome sequences of the two Italian strains share 99.7% to 97.8% of nucleotide identity with those available in GenBank. Results strengthen the hypothesis of PCV3 as a new emerging porcine circovirus, widespread all over the world. It follows the urgency of investigating in depth epidemiology and pathogenicity associated with this new virus.
Event horizons of astrophysical black holes and gravitational analogues have been predicted to excite the quantum vacuum and give rise to the emission of quanta, known as Hawking radiation. We ...experimentally create such a gravitational analogue using ultrashort laser pulse filaments and our measurements demonstrate a spontaneous emission of photons that confirms theoretical predictions.
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