309 research outputs found
Risk of heat illness in men and women: a systematic review and meta-analysis
Background Heat illness (HI) is a growing global concern; its incidence has risen dramatically across the world in recent years. The individual factors whereby elevated core temperature produces HI are not well-understood. Given known physiological differences between men and women pertaining to temperature regulation, we hypothesized that women would be at increased risk of HI than men. Objectives We aimed to determine the relative risk of HI in women compared with men through an exhaustive literature review and meta-analysis. Methods We search PubMed and Ovid Medline databases from inception to Apr 2017. Search terms included all permutations of sex and heat illness (including heatstroke and exertional heat illness) with no language restrictions. We included adult or adolescent human data reporting comparable male and female HI rates. One reviewer identified and screened titles and abstracts. Two independent reviewers applied eligibility criteria. Disagreements were resolved with a third reviewer. Results Of 5888 articles identified by searches, 36 were included in the systematic review and 22 in the meta-analysis. The mean (standard deviation) quality score was 3.31(1.25)/5. Overall the rate among women was consistently lower than men across the lifespan. The male: female pooled IRR was 2.28 (p<0.001, 95% CI: 1.66-3.16). There was modest heterogeneity (between-studies variance (Ï„2) = 0.02). The rates did not differ significantly when corrected for severity or occupation. Discussion The rate of HI was significantly increased in men compared with women. Risk for HI might be conferred by psychological and behavioral factors rather than physiological ones. Further research is required to delineate which groups are at greatest risk, leading to the development of mitigation strategies against HI
Mie-excitons: understanding strong coupling in dielectric nanoparticles
We theoretically analyse the hybrid Mie-exciton optical modes arising from the strong coupling of excitons in organic dyes or transition-metal dichalcogenides with the Mie resonances of high-index dielectric nanoparticles. Detailed analytic calculations show that silicon--exciton core--shell nanoparticles are characterised by a richness of optical modes which can be tuned through nanoparticle dimensions to produce large anticrossings in the visible or near infrared, comparable to those obtained in plexcitonics. The complex magnetic-excitonic nature of these modes is understood through spectral decomposition into Mie-coefficient contributions, complemented by electric and magnetic near-field profiles. In the frequency range of interest, absorptive losses in silicon are sufficiently low to allow observation of several periods of Rabi oscillations in strongly coupled emitter-particle architectures, as confirmed here by discontinuous Galerkin time-domain calculations for the electromagnetic field beat patterns. These results suggest that Mie resonances in high-index dielectrics are promising alternatives for plasmons in strong-coupling applications in nanophotonics, while the coupling of magnetic and electric modes opens intriguing possibilities for external control
Magnetic and Electric Mie-Exciton Polaritons in Silicon Nanodisks
Light-matter interactions at the nanoscale constitute a fundamental
ingredient for engineering applications in nanophotonics and quantum optics. To
this regard electromagnetic Mie resonances excited in high-refractive index
dielectric nanoparticles have recently attracted interest because of their
lower losses and better control over the scattering patterns compared to their
plasmonic metallic counterparts. The emergence of several resonances in those
systems results in an overall high complexity, where the electric and magnetic
dipoles have significant overlap in the case of spherical symmetry, thus
concealing the contributions of each resonance separately. Here we show,
experimentally and theoretically, the emergence of strong light-matter coupling
between the magnetic and electric-dipole resonances of individual silicon
nanodisks coupled to a J-aggregated organic semiconductor resonating at optical
frequencies, evidencing how the different properties of the two resonances
results in two different coupling strengths. The energy splittings observed are
of the same order of magnitude as in similar plasmonic systems, thus confirming
dielectric nanoparticles as promising alternatives for localized strong
coupling studies. The coupling of both the electric and magnetic dipole
resonances can offer interesting possibilities for the control of directional
light scattering in the strong-coupling regime and the dynamic tuning of
nanoscale light-matter coupled states by external fields
The anticipation, perception of affective touch in women with, recovered from Anorexia Nervosa
Disruptions in reward processing and anhedonia have long been observed in Anorexia Nervosa (AN). Interoceptive deficits have also been observed in AN, including reduced tactile pleasure. However, the extent to which this tactile anhedonia is specifically liked to an impairment in a specialized, interoceptive C-tactile system originating at the periphery, or a more top-down mechanism in the processing of tactile pleasantness remains debated. Here, we investigated differences between patients with and recovered from AN and healthy controls in the perception of pleasantness of touch delivered in a CT-optimal versus a CT-non-optimal manner, and in their top-down, anticipatory beliefs about the perceived pleasantness of touch. To this end, we measured the anticipated pleasantness of various materials touching the skin and the perceived pleasantness of light, dynamic touch applied to theforearmof 27 women with AN, 24 women who have recovered and 30 healthy controls using C Tactile (CT) afferents-optimal (slow) and non-optimal (fast) velocities. Our results showed that both clinical groups anticipated tactile experiences and rated delivered tactile stimuli as less pleasant than healthy controls, but the latter difference was not related to the CT optimality of the stimulation. Instead, differences in the perception of CT-optimal touch were predicted by differences in top-down beliefs, alexithymia and interoceptive sensibility. Thus, tactile anhedonia in AN might persist as a trait even after otherwise successful recovery of AN and it is not linked to a bottom-up interoceptive deficit in the CT system, but rather to a learned, defective top-down anticipation of tactile pleasantness
Gain-compensated cavities for the dynamic control of light-matter interactions
We propose an efficient approach for actively controlling the Rabi
oscillations in emitter-cavity hybrids based on the presence of an element with
optical gain. Inspired by recent developments in parity-time
()-symmetry photonics, we show that nano- or micro-cavities where
intrinsic losses are partially or fully compensated by an externally
controllable amount of gain offer unique capabilities for manipulating the
dynamics of emitters. In particular, one can drastically modify the dynamics of
the system, increase the overall occupation numbers, enhance the longevity of
the Rabi oscillations, and even decelerate them to the point where their
experimental observation becomes less challenging. Furthermore, we show that
there is a specific gain value that leads to an exceptional point, where both
emitter and cavity occupation oscillate practically in phase, with occupation
numbers that can significantly exceed unity. By revisiting a
recently-introduced Rabi-visibility measure, we provide robust guidelines for
quantifying the coupling strength and achieving strong-coupling with adaptable
Rabi frequency via loss compensation
Health-related quality of life assessment in eating disorders: adjustment and validation of a specific scale with the inclusion of an interpersonal domain
Purpose: Quality of life is a fundamental aspect of both clinical practice and research on eating disorders (ED) due to the significant impacts these disorders have on everyday life. Disorder-specific scales can improve the quality of research and findings and offer greater sensitivity and responsiveness. However, no specific instrument is available in Italian for ED. The aim of this paper is to adjust and to validate a reliable scale with specific items regarding physical and interpersonal well-being. Methods: The Italian version of the Eating Disorder Quality of Life (IEDQOL) scale was developed, on the basis of the original English scale, with the addition of items pertaining to physical well-being and interpersonal interactions. In this study, 180 ED patients and 190 healthy controls from the community were enrolled both from inpatient units and outpatient services. A statistical analysis with an exploratory factorial approach was performed in order to validate the tool. Results: The results showed that the IEDQOL has very good psychometric properties with test–retest validity and sensitivity between patients and controls (d = 2.17 for total score). Moreover, the interpersonal domain showed excellent psychometric values (Cronbach’s α > 0.70 in all the subgroups) and a robust correlation with other quality of life constructs. Conclusion: Future studies on the Italian population should use IEDQOL as outcome element that can be useful also with other disorder-specific psychopathological constructs and corroborate the reliability of the data. Future research in the ED field should only use this specific tool. Level of evidence: Case–control analytic study, Level III
Electrically controlled waveguide polariton laser
Exciton-polaritons are mixed light-matter particles offering a versatile
solid state platform to study many-body physical effects. In this work we
demonstrate an electrically controlled polariton laser, in a compact,
easy-to-fabricate and integrable configuration, based on a semiconductor
waveguide. Interestingly, we show that polariton lasing can be achieved in a
system without a global minimum in the polariton energy-momentum dispersion.
The surface cavity modes for the laser emission are obtained by adding couples
of specifically designed diffraction gratings on top of the planar waveguide,
forming an in-plane Fabry-Perot cavity. It is thanks to the waveguide geometry,
that we can apply a transverse electric field in order to finely tune the laser
energy and quality factor of the cavity modes. Remarkably, we exploit the
system sensitivity to the applied electric field to achieve an electrically
controlled population of coherent polaritons. The precise control that can be
reached with the manipulation of the grating properties and of the electric
field provides strong advantages to this device in terms of miniaturization and
integrability, two main features for the future development of coherent sources
from polaritonic technologies.Comment: 11 pages, 5 figures. Supplementary: 6 pages, 7 figure
Strongly enhanced light-matter coupling of a monolayer WS2 from a bound state in the continuum
Optical bound states in the continuum (BIC) allow to totally prevent a
photonic mode from radiating into free space along a given spatial direction.
Polariton excitations derived from the strong radiation-matter interaction of a
BIC with an excitonic resonance inherit an ultralong radiative lifetime and
significant nonlinearities due to their hybrid nature. However, maximizing the
light-matter interaction in these structures remains challenging, especially
with 2D semiconductors, thus preventing the observation of room temperature
nonlinearities of BIC polaritons. Here we show a strong light-matter
interaction enhancement at room temperature by coupling monolayer WS2 excitons
to a BIC, while optimizing for the electric field strength at the monolayer
position through Bloch surface wave confinement. By acting on the grating
geometry, the coupling with the active material is maximized in an open and
flexible architecture, allowing to achieve a 100 meV photonic bandgap with the
BIC in a local energy minimum and a record 70 meV Rabi splitting. Our novel
architecture provides large room temperature optical nonlinearities, thus
paving the way to tunable BIC-based polariton devices with
topologically-protected robustness to fabrication imperfections.Comment: 23 pages, 10 figur
On the applicability of quantum-optical concepts in strong-coupling nanophotonics
Rooted in quantum optics and benefiting from its well-established
foundations, strong coupling in nanophotonics has experienced increasing
popularity in recent years. With nanophotonics being an experiment-driven
field, the absence of appropriate theoretical methods to describe
ground-breaking advances has often emerged as an important issue. To address
this problem, the temptation to directly transfer and extend concepts already
available from quantum optics is strong, even if a rigorous justification is
not always available. In this Review we discuss situations where, in our view,
this strategy has indeed overstepped its bounds. We focus on exciton--plasmon
interactions, and particularly on the idea of calculating the number of
excitons involved in the coupling. We analyse how, starting from an unfounded
interpretation of the term N/V that appears in theoretical descriptions at
different levels of complexity, one might be tempted to make independent
assumptions for what the number N and the volume V are, and attempt to
calculate them separately. Such an approach can lead to different, often
contradictory results, depending on the initial assumptions (e.g. through
different treatments of as the -- ambiguous in plasmonics -- mode volume).
We argue that the source of such contradictions is the question itself -- How
many excitons are coupled?, which disregards the true nature of the coupled
components of the system, has no meaning and often not even any practical
importance. If one is interested in validating the quantum nature of the system
-- which appears to be the motivation driving the pursuit of strong coupling
with small N -- one could instead focus on quantities such as the photon
emission rate or the second-order correlation function
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