Vacuum Induced Coherences in Radiatively Coupled Multilevel Systems

We show that radiative coupling between two multilevel atoms having near-degenerate states can produce new interference effects in spontaneous emission. We explicitly demonstrate this possibility by considering two identical V systems each having a pair of transition dipole matrix elements which are orthogonal to each other. We discuss in detail the origin of the new interference terms and their consequences. Such terms lead to the evolution of certain coherences and excitations which would not occur otherwise. The special choice of the orientation of the transition dipole matrix elements enables us to illustrate the significance of vacuum induced coherence in multi-atom multilevel systems. These coherences can be significant in energy transfer studies.Comment: 13 pages including 8 figures in Revtex; submitted to PR

Transition from antibunching to bunching for two dipole-interacting atoms

It is known that there is a transition from photon antibunching to bunching in the resonance fluorescence of a driven system of two two-level atoms with dipole-dipole interaction when the atomic distance decreases and the other parameters are kept fixed. We give a simple explanation for the underlying mechanism which in principle can also be applied to other systems. PACS numbers 42.50.Ar, 42.50FxComment: Submitted to Phys. Rev. A; 15 pages Latex + 4 figure

Observation of squeezed light from one atom excited with two photons

Single quantum emitters like atoms are well-known as non-classical light sources which can produce photons one by one at given times, with reduced intensity noise. However, the light field emitted by a single atom can exhibit much richer dynamics. A prominent example is the predicted ability for a single atom to produce quadrature-squeezed light, with sub-shot-noise amplitude or phase fluctuations. It has long been foreseen, though, that such squeezing would be "at least an order of magnitude more difficult" to observe than the emission of single photons. Squeezed beams have been generated using macroscopic and mesoscopic media down to a few tens of atoms, but despite experimental efforts, single-atom squeezing has so far escaped observation. Here we generate squeezed light with a single atom in a high-finesse optical resonator. The strong coupling of the atom to the cavity field induces a genuine quantum mechanical nonlinearity, several orders of magnitude larger than for usual macroscopic media. This produces observable quadrature squeezing with an excitation beam containing on average only two photons per system lifetime. In sharp contrast to the emission of single photons, the squeezed light stems from the quantum coherence of photon pairs emitted from the system. The ability of a single atom to induce strong coherent interactions between propagating photons opens up new perspectives for photonic quantum logic with single emittersComment: Main paper (4 pages, 3 figures) + Supplementary information (5 pages, 2 figures). Revised versio

Increasing evidence for the important role of Labyrinthulomycetes in marine ecosystems

This review summarizes increasing evidence for the role of Labyrithulomycetes in marine ecosystems gathered over the last six decades. It focuses on their diversity, habitats, biomass, productivity and overall role in food webs and remineralization. Earlier studies contributed enormously to the cultured diversity of Labyrinthulomycetes. In recent years, their uncultured diversity has been demonstrated in exotic environments like the deep sea and anoxic waters. These findings emphasize the need for novel culture methods to grow these organisms. Many species seem to be substrate-specific in their occurrence. Their commensalistic or mutualistic occurrence in marine invertebrates deserves attention. The biomass of Labyrinthulomycetes in the water column may often match or even exceed that of bacteria, although such occurrences seem to be seasonal. There is a major knowledge gap on their productivity and turnover in the water column. The high biomass and production of several degradative enzymes indicate their importance as remineralizers in the ocean. However, the mechanisms by which they overcome bacterial competition are not clear. It is likely that they occupy special niches, such as marine aggregates. One role of the Labyrinthulomycetes suggested in this review, based on preliminary experiments, is that of ‘left-over scavenging’, following bacterial growth

Master equations for effective Hamiltonians

We reelaborate on a general method for obtaining effective Hamiltonians that describe different nonlinear optical processes. The method exploits the existence of a nonlinear deformation of the su(2) algebra that arises as the dynamical symmetry of the original model. When some physical parameter (usually related to the dispersive limit) becomes small, we immediately get a diagonal effective Hamiltonian that represents correctly the dynamics for arbitrary states and long times. We apply the same technique to obtain how the noise terms in the original model transform under this scheme, providing a systematic way of including damping effects in processes described in terms of effective Hamiltonians.Comment: 10 pages, no figure

Tensile and thermal properties of poly(lactic acid)/eggshell powder composite films

Biodegradable composite films of poly(lactic acid) (PLA)=eggshell powder (ESP) were prepared by the composite film casting method using chloroform as the solvent. ESP was loaded in PLA in 1 to 5 wt.%. The films were subjected to tensile, FT-IR spectral, thermogravimetric, X-ray, and microscopic analyses. The tensile strength and modulus of the composite films were found to be higher than those of PLA and increased with ESP content up to 4 wt.% and then decreased. A reverse trend was observed in the case of percentage elongation at break. The X-ray diffractograms of the composite films indicated an increase in crystallinity with ESP content. The optical micrographs indicated uniform distribution of ESP particles in the composite films. However, the fractographs indicated agglomeration of ESP particles at 5 wt.% loading. The FT-IR spectra revealed no specific interactions between PLA and ESP. The thermal stability of the composite films increased with ESP content

A study on effect of diabetes mellitus and hypertension on ocular blood flow by colour doppler ultrasonography

Background: Diabetes mellitus (DM) and hypertension (HT) have been the two major medical and public health issues for over 40 years worldwide. Colour doppler imaging (CDI) is widely used to evaluate ocular circulation. It is non-invasive, safe, and useful tool, most commonly used to investigate circulatory parameters in retrobulbar blood vessels. The aim was to study ocular blood flow (OBF) velocity in the ophthalmic artery (OA), central retinal artery (CRA) and central retinal vein (CRV) in patients with DM and HT by CDI. Materials and methods: A cross-sectional observational study was done for 6 months (June 2021–November 2021) on 40 patients of age 40 years and above with DM and/or HT of a minimum 6 months duration. Retrobulbar circulation was assessed in all subjects bilaterally. Subjects were further divided into groups with or without retinopathy. Results: Of the total number of 40 participants, 26 (65%) were male, and 14 (35%) were female. 16 (40%) participantswere diabetics, 8 (20%) were hypertensive, and 16 (40%) had both DM and HT. 57.5% were diagnosed with retinopathy changes. The mean values of the pulsatile index (PI) were: 1.23 in patients with DM, 1.30 in patients with HTN, and 1.33 in patients with DM and HTN. Conclusion: Our study showed reduced blood flow velocity and increased resistivity index (RI) in patientswith DM and/or HT. Significant changes were noted in retrobulbar blood flow in patients with retinopathy. Theseresults can potentially provide prognostic values in times to come regarding altered OBF even before retinopathydevelops

Potential benefits of Glycyrrhiza glabra (Liquorice) herb, its chemical make-up and significance in safeguarding poultry health: Current scientific knowledge

Positive results have been seen when bioactive components from herbal plants are added to poultry diets. Efficacy in feeding, digestion of nutrients, antioxidant health, immunological indices, and other factors can all be improved with the help of these additives, which in turn increases growth rates and improves poultry welfare. Several researchers have used sophisticated herbal formulae that included Glycyrrhiza glabra (Liquorice) as an ingredient. Epidemic illnesses, mainly in the respiratory, digestive, and immunological systems, pose the greatest threat to the poultry business. Flavonoids and glycyrrhizin are two of the bioactive compounds in Liquorice. The roots of this plant contain glycyrrhizin at concentrations of 1-9%, which has numerous pharmacological benefits, including anti-infectious, antioxidant, antiviral, and anti-inflammatory properties. Liquorice extracts are helpful in the treatment of multiple common illnesses. These include problems with the liver, the lungs, and the immunological system. Adding Liquorice to chicken diets improves their productivity in several ways, including fostering organ growth and stimulating digestion and appetite. Liquorice has many beneficial effects on birds, including helping them grow larger bodies, cleansing their systems, and protecting them from free radicals, bacteria, and inflammation. In this article, we'll look at the chemical make-up of liquorice herb, its role in protecting poultry health, and its recent applications and benefits

Racial, ethnic, and age disparities in the association of mental health symptoms and polysubstance use among persons in HIV care

We characterized polysubstance use burden and associations with mental health problems across demographic subgroups of PWH. In 2018–2020, as part of a primary care-based intervention study, PWH in care at three medical centers in Kaiser Permanente Northern California were screened for depression (PHQ-9≥10), anxiety (GAD-2≥3), and substance use (Tobacco, Alcohol, Prescription medication, and other Substance use [TAPS]≥1 per substance). We used Poisson regression to estimate prevalence ratios (PRs) comparing polysubstance use prevalence (TAPS≥1 for ≥2 substances) between PWH with positive screens for depression or anxiety vs. neither, among all PWH, and stratified by race/ethnicity and age (restricted to men), adjusting for sociodemographics, CD4, and HIV load. Screened PWH (N = 2865) included 92% men, 56% White, 19% Black, and 15% Hispanic PWH, with a median age of 55 years. Overall, polysubstance use prevalence was 26.4% (95% CI 24.9%-28.1%). PWH with depression or anxiety (n = 515) had an adjusted polysubstance use PR of 1.26 (1.09–1.46) vs. PWH with neither (n = 2350). Adjusted PRs were 1.47 (1.11–1.96), 1.07 (0.74–1.54), and 1.10 (0.85–1.41) among Black, Hispanic, and White men, respectively. Adjusted PRs did not differ by age group. Interventions should consider jointly addressing mental health and substance use problems and potential drivers, e.g. stigma or socioeconomic factors