Stochastic Single-Shot Polarization Pinning of Polariton Condensate at High Temperatures.

We resolve single-shot polariton condensate polarization dynamics, revealing a high degree of circular polarization persistent up to T=170 K. The statistical analysis of pulse-to-pulse polariton condensate polarization elucidates the stochastic nature of the polarization pinning process, which is strongly dependent on the pump laser intensity and polarization. Our experiments show that by spatial trapping and isolating condensates from their noisy environment it is possible to form strongly spin-polarized polariton condensates at high temperatures, offering a promising route to the realization of polariton spin lattices for quantum simulations.

Polariton condensate trapping by parametric pair scattering.

Spatially confined, trapped polariton condensates have been shown to exhibit strong stochastic on-site spin polarization and in longer polariton condensate chains, distance controlled ferromagnetic and antiferromagnetic spin couplings. Until now, little is known, on how such polariton condensates spatially separated from their exciton reservoirs are trapped and formed. Here, we investigate the properties and formation dynamics of two main families of polariton condensates, those overlapping with the pump reservoir and those in confined geometries, under pulsed nonresonant excitation. The observed reduction in polariton condensation threshold and energy blueshift in trapped case is attributed to exciton reservoir-condensate spatial separation, whereas time-resolved photoluminescence measurements, reveal distinct relaxation and condensate formation dynamics with pair parametric scattering process being the dominant relaxation mechanism in trapped geometry.

An exciton-polariton bolometer for terahertz radiation detection.

We experimentally investigate the feasibility of a bolometric device based on exciton-polaritons. Initial measurements presented in this work show that heating - via thermal expansion and bandgap renormalization - modifies the exciton-polariton propagation wavevector making exciton-polaritons propagation remarkably sensitive to thermal variations. By theoretical simulations we predict that using a single layer graphene absorbing layer, a THz bolometric sensor can be realized by a simple exciton-polariton ring interferometer device. The predicted sensitivity is comparable to presently existing THz bolometric devices with the convenience of being a device that inherently produces an optical signal output.

Author Correction: Hybrid organic-inorganic polariton laser.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Hybrid organic-inorganic polariton laser.

Organic materials exhibit exceptional room temperature light emitting characteristics and enormous exciton oscillator strength, however, their low charge carrier mobility prevent their use in high-performance applications such as electrically pumped lasers. In this context, ultralow threshold polariton lasers, whose operation relies on Bose-Einstein condensation of polaritons - part-light part-matter quasiparticles, are highly advantageous since the requirement for high carrier injection no longer holds. Polariton lasers have been successfully implemented using inorganic materials owing to their excellent electrical properties, however, in most cases their relatively small exciton binding energies limit their operation temperature. It has been suggested that combining organic and inorganic semiconductors in a hybrid microcavity, exploiting resonant interactions between these materials would permit to dramatically enhance optical nonlinearities and operation temperature. Here, we obtain cavity mediated hybridization of GaAs and J-aggregate excitons in the strong coupling regime under electrical injection of carriers as well as polariton lasing up to 200 K under non-resonant optical pumping. Our demonstration paves the way towards realization of hybrid organic-inorganic microcavities which utilise the organic component for sustaining high temperature polariton condensation and efficient electrical injection through inorganic structure.

Molecular clocks and the human condition: approaching their characterization in human physiology and disease.

Molecular clockworks knit together diverse biological networks and compelling evidence from model systems infers their importance in metabolism, immunological and cardiovascular function. Despite this and the diurnal variation in many aspects of human physiology and the phenotypic expression of disease, our understanding of the role and importance of clock function and dysfunction in humans is modest. There are tantalizing hints of connection across the translational divide and some correlative evidence of gene variation and human disease but most of what we know derives from forced desynchrony protocols in controlled environments. We now have the ability to monitor quantitatively ex vivo or in vivo the genome, metabolome, proteome and microbiome of humans in the wild. Combining this capability, with the power of mobile telephony and the evolution of remote sensing, affords a new opportunity for deep phenotyping, including the characterization of diurnal behaviour and the assessment of the impact of the clock on approved drug function.

A metabolomic study of adipose tissue in mice with a disruption of the circadian system.

Adipose tissue functions in terms of energy homeostasis as a rheostat for blood triglyceride, regulating its concentration, in response to external stimuli. In addition it acts as a barometer to inform the central nervous system of energy levels which can vary dramatically between meals and according to energy demand. Here a metabolomic approach, combining both Mass Spectrometry and Nuclear Magnetic Resonance spectroscopy, was used to analyse both white and brown adipose tissue in mice with adipocyte-specific deletion of Arntl (also known as Bmal1), a gene encoding a core molecular clock component. The results are consistent with a peripheral circadian clock playing a central role in metabolic regulation of both brown and white adipose tissue in rodents and show that Arntl induced global changes in both tissues which were distinct for the two types. In particular, anterior subcutaneous white adipose tissue (ASWAT) tissue was effected by a reduction in the degree of unsaturation of fatty acids, while brown adipose tissue (BAT) changes were associated with a reduction in chain length. In addition the aqueous fraction of metabolites in BAT were profoundly affected by Arntl disruption, consistent with the dynamic role of this tissue in maintaining body temperature across the day-night cycle and an upregulation in fatty acid oxidation and citric acid cycle activity to generate heat during the day when rats are inactive (increases in 3-hydroxybutyrate and glutamate), and increased synthesis and storage of lipids during the night when rats feed more (increased concentrations of glycerol, choline and glycerophosphocholine).

Relationships between vitamin D status and cardio-metabolic risk factors in young European adults.

BACKGROUND/AIMS: To explore associations between vitamin D and cardiovascular disease risk factors in young European adults. METHODS: This was a cross-sectional analysis of serum 25-hydroxyvitamin D [s25(OH)D], intact parathyroid hormone (iPTH) and biomarkers of cardiovascular disease risk in 195 healthy 20- to 40-year-olds (109 women) with a BMI between 27.5 and 32.5 from Iceland (64° N; n = 82), Ireland (51° N; n = 37) and Spain (42° N; n = 76) during mid-late winter. RESULTS: The median s25(OH)D was 52.8 nmol/l (IQR 38.1-69.9) or 21.1 ng/ml (IQR 15.2-28.0) with a latitude-dependent gradient (p ≤ 0.0001): Iceland, 41.7 nmol/l (IQR 32.7-54.2) or 16.7 ng/ml (IQR 13.1-21.7); Ireland, 52.9 nmol/l (IQR 35.3-68.6) or 21.2 ng/ml (IQR 14.1-27.4), and Spain, 67.1 nmol/l (IQR 47.1-87.1) or 26.8 ng/ml (IQR 18.8-34.8). Eleven percent of Icelandic participants had s25(OH)D concentrations <25 nmol/l (10 ng/ml) and 66% of Icelandic, 43% of Irish, and 30% of Spanish volunteers had concentrations <50 nmol/l (20 ng/ml), respectively. Overall, 17% met 3 or more of the NCEP/ATP III criteria for cardio-metabolic syndrome (MetS). Participants in the lowest third of s25(OH)D [≤ 42.5 nmol/l (17 ng/ml)] were more likely to have MetS (OR 2.49, p = 0.045) and elevated TAG (OR 3.46, p = 0.019). Individuals with iPTH concentrations in the lowest third [2.34 pmol/l (22.2 pg/ml)] were more likely to have elevated fasting TAG (OR 4.17, p = 0.039), insulin (OR 3.15, p = 0.029) and HOMA-IR (OR 2.15, p = 0.031), and they were less likely to have elevated IL-6 (OR 0.24, p = 0.003). CONCLUSION: There were interactions between s25(OH)D, iPTH and cardio-metabolic risk factors which, given the increasing prevalence of overweight and obesity and a low vitamin D status among adults, require randomised controlled vitamin D intervention studies in overweight persons.

Dietary supplementation with flaxseed oil lowers blood pressure in dyslipidaemic patients.

OBJECTIVE: Alpha-linolenic acid (ALA) is the natural precursor of the cardioprotective long-chain n-3 fatty acids. Available data indicate a possible beneficial effect of ALA on cardiovascular disease (CVD), but the response of various CVD risk factors to increased ALA intake is not well characterized. The purpose of the present study was to examine the effect of increased ALA intake on blood pressure in man. DESIGN, SETTING, SUBJECTS AND INTERVENTIONS: We used a prospective, two-group, parallel-arm design to examine the effect of a 12-week dietary supplementation with flaxseed oil, rich in ALA (8 g/day), on blood pressure in middle-aged dyslipidaemic men (n=59). The diet of the control group was supplemented with safflower oil, containing the equivalent n-6 fatty acid (11 g/day linoleic acid (LA); n=28). Arterial blood pressure was measured at the beginning and at the end of the dietary intervention period. RESULTS: Supplementation with ALA resulted in significantly lower systolic and diastolic blood pressure levels compared with LA (P=0.016 and P=0.011, respectively, from analysis of variance (ANOVA) for repeated measures). CONCLUSIONS: We observed a hypotensive effect of ALA, which may constitute another mechanism accounting in part for the apparent cardioprotective effect of this n-3 fatty acid.