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Coupling quantum emitters and nanostructures, in particular cold atoms and optical waveguides, has recently raised a large interest due to unprecedented possibilities of engineering light-matter interactions. In this work, we propose a new type of periodic dielectric waveguide that provides strong interactions between atoms and guided photons with an unusual dispersion. We design an asymmetric comb waveguide that supports a slow mode with a quartic (instead of quadratic) dispersion and an electric field that extends far into the air cladding for an optimal interaction with atoms. We compute the optical trapping potential formed with two guided modes at frequencies detuned from the atomic transition. We show that cold Rubidium atoms can be trapped as close as 100 nm from the structure in a 1.3-mK-deep potential well. For atoms trapped at this position, the emission into guided photons is largely favored, with a beta factor as high as 0.88 and a radiative decay rate into the slow mode 10 times larger than the free-space decay rate. These figures of merit are obtained at a moderately low group velocity of c/50.
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The human response to the COVID-19 pandemic set in motion an unprecedented shift in human activity with unknown long-term effects. The impacts in marine systems are expected to be highly dynamic at local and global scales. However, in comparison to terrestrial ecosystems, we are not well-prepared to document these changes in marine and coastal environments. The problems are two-fold: 1) manual and siloed data collection and processing, and 2) reliance on marine professionals for observation and analysis. These problems are relevant beyond the pandemic and are a barrier to understanding rapidly evolving blue economies, the impacts of climate change, and the many other changes our modern-day oceans are undergoing. The "Our Ocean in COVID-19â³ project, which aims to track human-ocean interactions throughout the pandemic, uses the new eOceans platform (eOceans.app) to overcome these barriers. Working at local scales, a global network of ocean scientists and citizen scientists are collaborating to monitor the ocean in near real-time. The purpose of this paper is to bring this project to the attention of the marine conservation community, researchers, and the public wanting to track changes in their area. As our team continues to grow, this project will provide important baselines and temporal patterns for ocean conservation, policy, and innovation as society transitions towards a new normal. It may also provide a proof-of-concept for real-time, collaborative ocean monitoring that breaks down silos between academia, government, and at-sea stakeholders to create a stronger and more democratic blue economy with communities more resilient to ocean and global change.
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Whale sharks (Rhincodon typus) - the largest extant fish species - reside in tropical environments, making them an exception to the general rule that animal size increases with latitude. How this largest fish thrives in tropical environments that promote high metabolism but support less robust zooplankton communities has not been sufficiently explained. We used open-source inertial measurement units (IMU) to log 397â h of whale shark behavior in Yucatán, Mexico, at a site of both active feeding and intense wildlife tourism. Here we show that the strategies employed by whale sharks to compensate for the increased drag of an open mouth are similar to ram feeders five orders of magnitude smaller and one order of magnitude larger. Presumed feeding constituted 20% of the total time budget of four sharks, with individual feeding bouts lasting up to 11 consecutive hours. Compared with normal, sub-surface swimming, three sharks increased their stroke rate and amplitude while surface feeding, while one shark that fed at depth did not demonstrate a greatly increased energetic cost. Additionally, based on time-depth budgets, we estimate that aerial surveys of shark populations should consider including a correction factor of 3 to account for the proportion of daylight hours that sharks are not visible at the surface. With foraging bouts generally lasting several hours, interruptions to foraging during critical feeding periods may represent substantial energetic costs to these endangered species, and this study presents baseline data from which management decisions affecting tourist interactions with whale sharks may be made.
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Tubarões , Natação , Animais , Espécies em Perigo de Extinção , Masculino , MéxicoRESUMO
We investigate the quantum entanglement of the three modes associated with the three-photon states obtained by triple-photon generation in a phase-matched third-order nonlinear optical interaction. Although the second-order processes have been extensively dealt with, there is no direct analogy between the second and third-order mechanisms. We show, for example, the absence of quantum entanglement between the quadratures of the three modes in the case of spontaneous parametric triple-photon generation. However, we show robust, seeding-dependent, genuine triple-photon entanglement in the fully seeded case.
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We investigate the basic mechanism of nonlinear mode competition in two semiconductor-coupled nanocavities operating in the laser regime. For this, we study energy transfer between bonding (in-phase) and anti-bonding (out-of-phase) modes of the system formed by two strongly coupled photonic crystal nanolasers. We experimentally observe mode switching from the blue-detuned to the red-detuned mode as the pump power is increased. A semi-classical description in terms of mean-field equations allows us to explain this phenomenon as stimulated scattering due to carrier population oscillations in the cavities at the mode splitting frequency. We predict such asymmetrical mode interaction to be universal in arrays of optically coupled semiconductor micro and nanocavities.
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We demonstrate a large tuning of the coupling strength in Photonic Crystal molecules without changing the inter-cavity distance. The key element for the design is the "photonic barrier engineering", where the "potential barrier" is formed by the air-holes in between the two cavities. This consists in changing the hole radius of the central row in the barrier. As a result we show, both numerically and experimentally, that the wavelength splitting in two evanescently-coupled Photonic Crystal L3 cavities (three holes missing in the ΓK direction of the underlying triangular lattice) can be continuously controlled up to 5× the initial value upon â¼ 30% of hole-size modification in the barrier. Moreover, the sign of the splitting can be reversed in such a way that the fundamental mode can be either the symmetric or the anti-symmetric one without altering neither the cavity geometry nor the inter-cavity distance. Coupling sign inversion is explained in the framework of a Fabry-Perot model with underlying propagating Bloch modes in coupled W1 waveguides.
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We present a coupler design allowing normally-incident light coupling from free-space into a monomode photonic crystal waveguide operating in the slow-light regime. Numerical three-dimensional calculations show that extraction efficiencies as high as 80% can be achieved for very large group indices up to 100. We demonstrate experimentally the device feasibility by coupling and extracting light from a photonic crystal waveguide over a large group-index range (from 10 to 60). The measurements are in good agreement with theoretical predictions. We also study numerically the impact of various geometrical parameters on the coupler performances.
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We start from a 2D photonic crystal nanocavity with moderate Q-factor and dynamically increase it by two order of magnitude by the joint action of coherent population oscillations and nonlinear refractive index.
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Simulação por Computador , Luz , Nanotecnologia/instrumentação , Dispositivos Ópticos , Fótons , Refratometria/instrumentação , Espalhamento de Radiação , Desenho Assistido por Computador , Cristalização , Desenho de Equipamento , Dinâmica não LinearRESUMO
We report on far-field measurements of L3 photonic crystal (PhC) cavities with high quality beaming. This is achieved by means of the so-called "band folding" technique, in which a modulation of the radius of specific holes surrounding the cavity is introduced. Far-field patterns are measured from photoluminescence of quantum wells embedded in the PhC. A very good agreement between experimental results and simulated radiation patterns has been found. Laser effect is demonstrated in the beaming cavity with a threshold comparable to the regular one. In addition, free-space input coupling to this cavity has been achieved. In order to fully analyze the coupling efficiency, we generalize the approach developed in S. Fan, et al., [J. Opt. Soc. Am. A 20, 569 (2003)], relaxing the hypothesis of mirror symmetry. The obtained coupling efficiencies are about 15% with quality factors (Q) exceeding 10(4). These results further validate the "folding" technique on L3 cavities for nanocavity realization with efficient free-space coupling and high Q factors.
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Nanoestruturas/química , Nanotecnologia/instrumentação , Ressonância de Plasmônio de Superfície/instrumentação , Transdutores , Desenho Assistido por Computador , Cristalização , Desenho de Equipamento , Análise de Falha de Equipamento , Luz , Espalhamento de RadiaçãoRESUMO
Phase-matched third-harmonic generation is demonstrated in a germanium-doped optical fiber. Green light at 514.4 nm is generated in an LP(03) mode when a pump field at ~1543.3 nm is launched into the fiber in the fundamental LP(01) mode. The phase matching is achieved for a particular combination of the germanium doping concentration and the fiber core diameter.
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Slow light induced by coherent population oscillations and cavity dispersive nonlinear response are combined achieving 2 orders of magnitude enhancement of the group delay and an equivalent decreasing of the spectral linewidth of a L3 two-dimensional photonic crystal nanocavity.
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BACKGROUND: One aim of personalized medicine is to determine which treatment is to be preferred for an individual patient, given all patient information available. Particularly in mental health, however, there is a lack of a single objective, reliable measure of outcome that is sensitive to crucial individual differences among patients. METHOD: We examined the feasibility of quantifying the total clinical value provided by a treatment (measured by both harms and benefits) in a single metric. An expert panel was asked to compare 100 pairs of patients, one from each treatment group, who had participated in a randomized clinical trial (RCT) involving interpersonal psychotherapy (IPT) and escitalopram, selecting the patient with the preferred outcome considering both benefits and harms. RESULTS: From these results, an integrated preference score (IPS) was derived, such that the differences between any two patients' IPSs would predict the clinicians' preferences. This IPS was then computed for all patients in the RCT. A second set of 100 pairs was rated by the panel. Their preferences were highly correlated with the IPS differences (r=0.84). Finally, the IPS was used as the outcome measure comparing IPT and escitalopram. The 95% confidence interval (CI) for the effect size comparing treatments indicated clinical equivalence of the treatments. CONCLUSIONS: A metric that combines benefits and harms of treatments could increase the value of RCTs by making clearer which treatments are preferable and, ultimately, for whom. Such methods result in more precise estimation of effect sizes, without increasing the required sample size.
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Modelos Estatísticos , Avaliação de Resultados em Cuidados de Saúde/métodos , Medicina de Precisão , Ensaios Clínicos Controlados Aleatórios como Assunto/estatística & dados numéricos , Adulto , Antidepressivos de Segunda Geração/uso terapêutico , Citalopram/uso terapêutico , Intervalos de Confiança , Interpretação Estatística de Dados , Transtorno Depressivo/terapia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Variações Dependentes do Observador , Avaliação de Resultados em Cuidados de Saúde/estatística & dados numéricos , Psicoterapia , Equivalência TerapêuticaRESUMO
In this Letter we study spontaneous generation of triple photon states in optical fibers by third order spontaneous downconversion. Using a semiclassical approach we derive an explicit expression for the triple photons generation efficiency as a function of fiber parameters. We show that optical fibers with well suited index profiles and standard outer diameters could be the key component of future triple photons sources.
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Slow light propagation is demonstrated by implementing Coherent Population Oscillations in a silica fiber doped with erbium ions in a ring surrounding the single mode core. Though only the wings of the mode interact with erbium ions, group velocities around 1360 m/s are obtained without any spatial distortion of the propagating mode.
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Tecnologia de Fibra Óptica , Lasers de Estado Sólido , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Luz , Espalhamento de RadiaçãoRESUMO
We demonstrate an easy-to-implement scheme for fluorescence enhancement and observation volume reduction using photonic crystals (PhCs) as substrates for microscopy. By normal incidence coupling to slow 2D-PhC guided modes, a 65 fold enhancement in the excitation is achieved in the near field region (100 nm deep and 1 microm wide) of the resonant mode. Such large enhancement together with the high spatial resolution makes this device an excellent substrate for fluorescence microscopies.
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Meios de Contraste/química , Cristalização/métodos , Corantes Fluorescentes/química , Aumento da Imagem/métodos , Microscopia de Fluorescência/métodos , Meios de Contraste/análise , Corantes Fluorescentes/análise , Propriedades de SuperfícieRESUMO
BACKGROUND: Although interpersonal psychotherapy (IPT) is an efficacious treatment for acute depression, the relative efficacy of treatment in each of the four IPT problem areas (grief, role transitions, role disputes, interpersonal deficits) has received little attention. We evaluated the specificity of IPT by comparing treatment success among patients whose psychotherapy focused on each problem area. Moreover, we sought to understand how the patient characteristics and interpersonal problems most closely linked to the onset of a patient's current depression contributed to IPT success. METHODS: Patients meeting DSM-IV criteria for an episode of major depressive disorder (n=182) were treated with weekly IPT. Remission was defined as an average Hamilton Rating Scale for Depression 17-item score of 7 or below over 3 weeks. Personality disorders were diagnosed using the Structured Clinical Interview for DSM-IV Personality Disorders. RESULTS: Contrary to our prediction that patients whose treatment was focused on interpersonal deficits would take longer to remit, survival analyses indicated that patients receiving treatment focused on each of the four problem areas did not differ in their times to remission. Nor were patients in the interpersonal deficits group more likely to have an Axis II diagnosis. Patients whose treatment focused on role transitions remitted faster than those whose treatment focused on role disputes, after controlling for covariates. CONCLUSION: With skillful use of IPT strategies and tactics and with careful medication management where appropriate, patients in this study whose treatment focused on each problem area were treated with equal success by trained IPT clinicians.
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Transtorno Depressivo Maior/psicologia , Transtorno Depressivo Maior/terapia , Relações Interpessoais , Psicoterapia/métodos , Adolescente , Adulto , Transtorno Depressivo Maior/diagnóstico , Manual Diagnóstico e Estatístico de Transtornos Mentais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Resultado do Tratamento , Adulto JovemRESUMO
Linear and non-linear thermo-optical dynamical regimes were investigated in a photonic crystal cavity. First, we have measured the thermal relaxation time in an InP-based nano-cavity with quantum dots in the presence of optical pumping. The experimental method presented here allows one to obtain the dynamics of temperature in a nanocavity based on reflectivity measurements of a cw probe beam coupled through an adiabatically tapered fiber. Characteristic times of 1.0+/-0.2 micros and 0.9+/-0.2 micros for the heating and the cooling processes were obtained. Finally, thermal dynamics were also investigated in a thermo-optical bistable regime. Switch-on/off times of 2 micros and 4 micros respectively were measured, which could be explained in terms of a simple non-linear dynamical representation.
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In homogeneous arrays of coupled waveguides, Floquet-Bloch waves are known to travel freely across the waveguides. We introduce a systematic discussion of the built-in patterning of the coupling constant between neighboring waveguides. Key patterns provide functions such as redirecting, guiding, and focusing these waves, up to nonlinear all-optical routing. This opens the way to light control in a functionalized discrete space, i.e., discrete photonics.
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The engineered fusion protein NPT088 targets amyloid in vitro and in animal models of Alzheimer's disease. Previous studies showed that NPT088 treatment reduced ß-amyloid plaque and tau aggregate loads in mouse disease models. Here, we present the results from an initial clinical study of NPT088 in patients with mild to moderate Alzheimer's disease. Patients were treated with 4 dose levels of NPT088 for 6 months to evaluate its safety and tolerability. Exploratory measurements included measurement of change in ß-amyloid plaque and tau burden utilizing Positron Emission Tomography imaging as well as measures of Alzheimer's disease symptoms. At endpoint NPT088 was generally safe and well-tolerated with the most prominent finding being infusion reactions in a minority of patients. No effect of NPT088 on brain plaques, tau aggregates or Alzheimer's disease symptoms was observed.
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Doença de Alzheimer/tratamento farmacológico , Encéfalo/diagnóstico por imagem , Placa Amiloide/diagnóstico por imagem , Proteínas Recombinantes de Fusão/uso terapêutico , Idoso , Idoso de 80 Anos ou mais , Doença de Alzheimer/diagnóstico por imagem , Doença de Alzheimer/fisiopatologia , Doença de Alzheimer/psicologia , Peptídeos beta-Amiloides/metabolismo , Compostos de Anilina , Bacteriófago M13/genética , Encéfalo/metabolismo , Relação Dose-Resposta a Droga , Etilenoglicóis , Feminino , Humanos , Fragmentos Fc das Imunoglobulinas/genética , Masculino , Pessoa de Meia-Idade , Placa Amiloide/metabolismo , Tomografia por Emissão de Pósitrons , Proteínas tau/metabolismoRESUMO
The name given to functional neurologic symptoms has evolved over time in the different editions of the International Classification of Diseases (ICD) and the Diagnostic and Statistical Manual of Mental Disorders (DSM), reflecting a gradual move away from an etiologic conception rooted in hysterical conversion to an empiric phenomenologic one, emphasizing the central role of the neurologic examination and testing in demonstrating that the symptoms are incompatible with recognized neurologic disease pathophysiology, or are internally inconsistent.