168 research outputs found
Restoring Lake Urmia: Moving beyond a Uniform Lake Level (2-page Summary)
More than 5 million people live near Lake Urmia in northwestern Iran, one of the world\u27s largest hypersaline lakes. Over the past two decades, the lake has lost 95% of its volume, lake level has dropped more than 7 m, and lake restoration has gained widespread interest. The government seeks a uniform ecological target lake level of 1274.1 m above sea level to lower salinity below 240 gL-1 and recover brine shrimp (Artemia spp.) and flamingos (Phoenicopterus roseus).
We have synthesized over 40 years of available data, defined 8 ecosystem services for human health, water quality, ecology, recreation, and economy (Box 1), and related each service to lake levels with uncertainties (Box 2)
Hybrid Group IV Nanophotonic Structures Incorporating Diamond Silicon-Vacancy Color Centers
We demonstrate a new approach for engineering group IV semiconductor-based
quantum photonic structures containing negatively charged silicon-vacancy
(SiV) color centers in diamond as quantum emitters. Hybrid SiC/diamond
structures are realized by combining the growth of nanoand micro-diamonds on
silicon carbide (3C or 4H polytype) substrates, with the subsequent use of
these diamond crystals as a hard mask for pattern transfer. SiV color
centers are incorporated in diamond during its synthesis from molecular diamond
seeds (diamondoids), with no need for ionimplantation or annealing. We show
that the same growth technique can be used to grow a diamond layer controllably
doped with SiV on top of a high purity bulk diamond, in which we
subsequently fabricate nanopillar arrays containing high quality SiV
centers. Scanning confocal photoluminescence measurements reveal optically
active SiV lines both at room temperature and low temperature (5 K) from
all fabricated structures, and, in particular, very narrow linewidths and small
inhomogeneous broadening of SiV lines from all-diamond nano-pillar arrays,
which is a critical requirement for quantum computation. At low temperatures (5
K) we observe in these structures the signature typical of SiV centers in
bulk diamond, consistent with a double lambda. These results indicate that high
quality color centers can be incorporated into nanophotonic structures
synthetically with properties equivalent to those in bulk diamond, thereby
opening opportunities for applications in classical and quantum information
processing
Observation of mollow triplets with tunable interactions in double lambda systems of individual hole spins
Although individual spins in quantum dots have been studied extensively as qubits, their investigation under strong resonant driving in the scope of accessing Mollow physics is still an open question. Here, we have grown high quality positively charged quantum dots embedded in a planar microcavity that enable enhanced light-matter interactions. Under a strong magnetic field in the Voigt configuration, individual positively charged quantum dots provide a double lambda level structure. Using a combination of above-band and resonant excitation, we observe the formation of Mollow triplets on all optical transitions. We find that when the strong resonant drive power is used to tune the Mollow-triplet lines through each other, we observe anticrossings. We also demonstrate that the interaction that gives rise to the anticrossings can be controlled in strength by tuning the polarization of the resonant laser drive. Quantum-optical modeling of our system fully captures the experimentally observed spectra and provides insight on the complicated level structure that results from the strong driving of the double lambda system
Ultrafast coherent manipulation of trions in site-controlled nanowire quantum dots
Physical implementations of large-scale quantum processors based on solid-state platforms benefit from realizations of quantum bits positioned in regular arrays. Self-assembled quantum dots are well established as promising candidates for quantum optics and quantum information processing, but they are randomly positioned. Site-controlled quantum dots, on the other hand, are grown in pre-defined locations but have not yet been sufficiently developed to be used as a platform for quantum information processing. In this paper, we demonstrate all-optical ultrafast complete coherent control of a qubit formed by the single-spin/trion states of a charged site-controlled nanowire quantum dot. Our results show that site-controlled quantum dots in nanowires are promising hosts of charged-exciton qubits and that these qubits can be cleanly manipulated in the same fashion as has been demonstrated in randomly positioned quantum dot samples. Our findings suggest that many of the related excitonic qubit experiments that have been performed over the past 15 years may work well in the more scalable, site-controlled systems, making them very promising for the realization of quantum hardware
PPARγ1 and LXRα face a new regulator of macrophage cholesterol homeostasis and inflammatory responsiveness, AEBP1
Peroxisome proliferator-activated receptor γ1 (PPARγ1) and liver X receptor α (LXRα) are nuclear receptors that play pivotal roles in macrophage cholesterol homeostasis and inflammation; key biological processes in atherogenesis. The activation of PPARγ1 and LXRα by natural or synthetic ligands results in the transactivation of ABCA1, ABCG1, and ApoE; integral players in cholesterol efflux and reverse cholesterol transport. In this review, we describe the structure, isoforms, expression pattern, and functional specificity of PPARs and LXRs. Control of PPARs and LXRs transcriptional activity by coactivators and corepressors is also highlighted. The specific roles that PPARγ1 and LXRα play in inducing macrophage cholesterol efflux mediators and antagonizing macrophage inflammatory responsiveness are summarized. Finally, this review focuses on the recently reported regulatory functions that adipocyte enhancer-binding protein 1 (AEBP1) exerts on PPARγ1 and LXRα transcriptional activity in the context of macrophage cholesterol homeostasis and inflammation
Spectrally reconfigurable quantum emitters enabled by optimized fast modulation
The ability to shape photon emission facilitates strong photon-mediated
interactions between disparate physical systems, thereby enabling applications
in quantum information processing, simulation and communication. Spectral
control in solid state platforms such as color centers, rare earth ions, and
quantum dots is particularly attractive for realizing such applications
on-chip. Here we propose the use of frequency-modulated optical transitions for
spectral engineering of single photon emission. Using a scattering-matrix
formalism, we find that a two-level system, when modulated faster than its
optical lifetime, can be treated as a single-photon source with a widely
reconfigurable photon spectrum that is amenable to standard numerical
optimization techniques. To enable the experimental demonstration of this
spectral control scheme, we investigate the Stark tuning properties of the
silicon vacancy in silicon carbide, a color center with promise for optical
quantum information processing technologies. We find that the silicon vacancy
possesses excellent spectral stability and tuning characteristics, allowing us
to probe its fast modulation regime, observe the theoretically-predicted
two-photon correlations, and demonstrate spectral engineering. Our results
suggest that frequency modulation is a powerful technique for the generation of
new light states with unprecedented control over the spectral and temporal
properties of single photons.Comment: 9 pages, 6 figures; Supplementary Informatio
Frequency-resolved Monte Carlo
We adapt the Quantum Monte Carlo method to the cascaded formalism of quantum optics, allowing us to simulate the emission of photons of known energy. Statistical processing of the photon clicks thus collected agrees with the theory of frequency-resolved photon correlations, extending the range of applications based on correlations of photons of prescribed energy, in particular those of a photon-counting character. We apply the technique to autocorrelations of photon streams from a two-level system under coherent and incoherent pumping, including the Mollow triplet regime where we demonstrate the direct manifestation of leapfrog processes in producing an increased rate of two-photon emission events
The use of contextualised standardised client simulation to develop clinical reasoning in final year veterinary students
Clinical reasoning is an important skill for veterinary students to develop before graduation. Simulation has been studied in medical education as a method for developing clinical reasoning in students, but evidence supporting it is limited. This study involved the creation of a contextualized, standardized client simulation session that aimed to improve the clinical reasoning ability and confidence of final-year veterinary students. Sixty-eight participants completed three simulated primary-care consultations, with the client played by an actor and the pet by a healthy animal. Survey data showed that all participants felt that the session improved their clinical decision-making ability. Quantitative clinical reasoning self-assessment, performed using a validated rubric, triangulated this finding, showing an improvement in students’ perception of several components of their clinical reasoning skill level from before the simulation to after it. Blinded researcher analysis of the consultation video recordings found that students showed a significant increase in ability on the history-taking and making-sense-of-data (including formation of a differential diagnosis) components of the assessment rubric. Thirty students took part in focus groups investigating their experience with the simulation. Two themes arose from thematic analysis of these data: variety of reasoning methods and “It’s a different way of thinking.” The latter highlights differences between the decision making students practice during their time in education and the decision making they will use once they are in practice. Our findings suggest that simulation can be used to develop clinical reasoning in veterinary students, and they demonstrate the need for further research in this area
Narcissism and the strategic pursuit of short-term mating : universal links across 11 world regions of the International Sexuality Description Project-2.
Previous studies have documented links between sub-clinical narcissism and the active pursuit of short-term mating strategies (e.g., unrestricted sociosexuality, marital infidelity, mate poaching). Nearly all of these investigations have relied solely on samples from Western cultures. In the current study, responses from a cross-cultural survey of 30,470 people across 53 nations spanning 11 world regions (North America, Central/South America, Northern Europe, Western Europe, Eastern Europe, Southern Europe, Middle East, Africa, Oceania, Southeast Asia, and East Asia) were used to evaluate whether narcissism (as measured by the Narcissistic Personality Inventory; NPI) was universally associated with short-term mating. Results revealed narcissism scores (including two broad factors and seven traditional facets as measured by the NPI) were functionally equivalent across cultures, reliably associating with key sexual outcomes (e.g., more active pursuit of short-term mating, intimate partner violence, and sexual aggression) and sex-related personality traits (e.g., higher extraversion and openness to experience). Whereas some features of personality (e.g., subjective well-being) were universally associated with socially adaptive facets of Narcissism (e.g., self-sufficiency), most indicators of short-term mating (e.g., unrestricted sociosexuality and marital infidelity) were universally associated with the socially maladaptive facets of narcissism (e.g., exploitativeness). Discussion addresses limitations of these cross-culturally universal findings and presents suggestions for future research into revealing the precise psychological features of narcissism that facilitate the strategic pursuit of short-term mating
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