A Liquid Mirror Resonator.

We present the first experimental demonstration of a Fabry‒Perot resonator that utilizes total internal reflection from a liquid-gas interface. Our hybrid resonator hosts both optical and capillary waves that mutually interact. Except for the almost perfect reflection by the oil-air interface at incident angles smaller than the critical angle, reflections from the liquid-phase boundary permit optically examining thermal fluctuations and capillary waves at the oil surface.

Design and Fabrication of an Optical Fiber Made of Water.

In this report, an optical fiber of which the core is made solely of water, while the cladding is air, is designed and manufactured. In contrast with solid-cladding devices, capillary oscillations are not restricted, allowing the fiber walls to move and vibrate. The fiber is constructed by a high direct current (DC) voltage of several thousand volts (kV) between two water reservoirs that creates a floating water thread, known as a water bridge.

Cavity optofluidics: a μdroplet's whispering-gallery mode makes a μvortex.

We experimentally demonstrate light-flow interaction, in which the angular momentum of circulating light excites micro-vortices. In contrast with the solid-phase of matter, where one has to overcome static friction in order to start motion, liquids have no "static drag." Relevant to almost all optofluidic micro-systems hence, μWatt optical power is sufficient to start flows, even in liquids 50 times more viscous than water.

Flying couplers above spinning resonators generate irreversible refraction.

Creating optical components that allow light to propagate in only one direction-that is, that allow non-reciprocal propagation or 'isolation' of light-is important for a range of applications. Non-reciprocal propagation of sound can be achieved simply by using mechanical components that spin. Spinning also affects de Broglie waves , so a similar idea could be applied in optics.

Light and Capillary Waves Propagation in Water Fibers.

The confinement of light and sound, while they are traveling in fibers, enables a variety of light-matter interactions. Therefore, it is natural to ask if fibers can also host capillary waves. Capillary waves are similar to those we see when throwing a stone into a puddle.

Regular oscillations and random motion of glass microspheres levitated by a single optical beam in air: publisher's note.

This publisher's note amends a recent publication [Opt. Express24(3), 2850-2857 (2016)] to include Acknowledgments.

Regular oscillations and random motion of glass microspheres levitated by a single optical beam in air.

We experimentally report on optical binding of many glass particles in air that levitate in a single optical beam. A diversity of particle sizes and shapes interact at long range in a single Gaussian beam. Our system dynamics span from oscillatory to random and dimensionality ranges from 1 to 3D.

Water-walled microfluidics for high-optical finesse cavities.

In submerged microcavities there is a tradeoff between resonant enhancement for spatial water and light overlap. Why not transform the continuously resonating optical mode to be fully contained in a water microdroplet per se? Here we demonstrate a sustainable 30-μm-pure water device, bounded almost completely by free surfaces, enabling >1,000,000 re-circulations of light. The droplets survive for >16 h using a technique that is based on a nano-water bridge from the droplet to a distant reservoir to compensate for evaporation.

Optical binding in white light.

We experimentally demonstrate, for the first time, binding of aerosols of various sizes and shapes in white light. The optomechancial interaction between particles is long range and is in the underdamped regime. Incoherency allows mitigation of interference fringes to enable monotonically changing the distance between particles from 60 μm to contact, constituting a parametrically controlled testbed for transition studies at new scales.

Rashba-type plasmonic metasurface.

Observation of the plasmonic Rashba effect manifested by a polarization helicity degeneracy removal in a surface wave excitation via an inversion asymmetric metamaterial is reported. By designing the metasurface symmetry using anisotropic nanoantennas with space-variant orientations, we govern the light-matter interaction via the local field distribution arising in a wavelength and a photon spin control. The broken spatial inversion symmetry is experimentally manifested by a directional excitation of surface wave jets observed via a decoupling slit as well as by the quantum dot fluorescence.

Nitric oxide synthase in acute alteration of nitric oxide levels after subarachnoid hemorrhage.

Objective: Subarachnoid hemorrhage (SAH) is associated with acute decreases and subsequent recovery of cerebral nitric oxide (NO) levels, but the mechanisms of these alterations are not known. In this study, we measured NO synthase (NOS) protein and kinetics to determine its involvement in the alterations of cerebral NO levels after SAH.

Methods: The endovascular rat model of SAH was used.

Agonist concentration-dependent differential responsivity of a human platelet purinergic receptor: pharmacological and kinetic studies of aggregation, deaggregation and shape change responses mediated by the purinergic P2Y1 receptor in vitro.

Platelet shape change (SC), aggregation and deaggregation responses are integral components of hemostasis that are elicited and modulated in vivo by the simultaneous activation of several membrane receptors. Selective activation of the purinergic P2Y1 receptor in vivo elicits a sustained SC and a small, transient aggregation response that is reversed rapidly by a robust deaggregation response (Platelets 2003; 14: 89). Using a kinetics-based turbidimetric approach to study the modulation of these concurrent components of human platelet responses, we demonstrate that these P2Y1 receptor-related responses and a number of their kinetic and steady-state characteristics are differentially elicited and modulated.

Diversity of signaling underlying responses mediated by selective activation of the platelet thromboxane A2 (TXA2) receptor; pharmacological and kinetic studies in vitro.

Selective activation of the platelet TXA2 receptor is sufficient to mediate concurrent aggregation, deaggregation and shape change (SC) responses without activation of known Gi-coupled receptors (Platelets 2003; 14: 89). However, Gi-coupled receptor activation strongly influences the hemostasis response in vivo. This study investigated the modulatory effects of two signaling pathways related to Gi-coupled receptor activation, stimulation of phosphoinositide 3-kinases (PI3Ks) and inhibition of adenylyl cyclase (AC), on the aggregation, deaggregation and SC components of the platelet activation response.

Different pharmacological properties of two equipotent antagonists (clozapine and rauwolscine) for 5-HT2B receptors in rat stomach fundus.

On the basis of the previously demonstrated constitutive activity in natural systems and the possibility of specific ligand-induced conformations, the aims of this study were: (i) to characterize the effects of two competitive antagonists (rauwolscine, RAU and clozapine, CLO) with very similar potencies for 5-HT(2B) receptors in a natural system (rat stomach fundus), and (ii) to evaluate a new method for detecting ligand-specific generated conformations through the study of the effects of RAU and CLO in 5-HT efficacy and in the time course of the response to the agonists. RAU and CLO behaved as competitive antagonists and showed similar potencies (pA(2) 7.56+/-0.

Concurrent responses elicited by isolated activation of platelet Gq-coupled receptors, in vitro: a novel approach for their separation and analysis.

This study tested the hypothesis that aggregation mediated by activation of a single G(q)-coupled receptor can be studied quantitatively if four concurrent but distinct components of the observed platelet response, autocrine stimulation, shape change (SC), aggregation and deaggregation, are separately measured. Responses mediated by two G(q)-coupled receptors, the TXA(2) and the P2Y(1), were assayed by a novel, kinetics-based turbidimetric approach. Blocking the autocrine stimulation with a cocktail of receptor antagonists revealed rapid and sustained SC that largely masked the aggregation.

Molecular and biochemical evidence for the presence of type III adenylyl cyclase in human platelets.

The isoform(s) of adenylyl cyclase (AC) present in human platelets has not been identified, and evidence supporting a role for AC in platelet aggregation is equivocal. We recently characterized deaggregation as an active component of the platelet aggregation response that may be an important determinant of the extent and duration of aggregation. G(i)-coupled receptors are linked to the inhibition of AC and are targets of antiplatelet drugs.

Activation of the alpha(2A)-adrenoceptor mediates deceleration of the deaggregation component of the response to ADP or 5-HT in human platelets in vitro.

Platelet aggregation requires the concomitant activation of at least one G(i)- and one G(q)-coupled receptor. Epinephrine (EPI) amplifies the response elicited by a number of agonists for platelet aggregation. This study tested the hypothesis that platelet alpha(2A)-adrenoceptor activation causes deceleration of the deaggregation component of the platelet aggregation response when activated concomitantly with the G(q)-coupled adenosine diphosphate (ADP) P2Y(1) or 5-hydroxytryptamine(2A) receptor.

Differences in rapid desensitization of 5-hydroxytryptamine2A and 5-hydroxytryptamine2C receptor-mediated phospholipase C activation.

The serotonin (5-HT)2A and 5-HT2C receptors share a high degree of sequence homology and have very similar pharmacological profiles. Although it is generally believed that the cellular signal transduction mechanisms activated by these receptors are indistinguishable, recent data suggest significant differences in their signaling cascades. In this study we explored differences in the characteristics and mechanisms of rapid desensitization between the 5-HT2A and 5-HT2C receptor systems.

Deaggregation is an integral component of the response of platelets to ADP in vitro: kinetic studies of literature and original data.

Adenosine diphosphate (ADP) is recognized as an important mediator of platelet aggregation. Transient aggregation at low (< or =1 microM), and sustained aggregation at higher ADP concentrations are consistently observed. Dissociation of platelet aggregates has been described and may explain the reversible component of the aggregation response.

Activation of Gi-coupled receptors releases a tonic state of inhibited platelet aggregation.

Single-receptor pharmacology does not satisfactorily explain the physiology of the ADP-induced platelet aggregation response. It has been shown that, in addition to Gq-coupled receptor activation, one Gi-coupled receptor, either the ADP P2T or the alpha2-adrenoceptor, is required for elicitation of aggregation. The underlying mechanism of this action, however, has not been elucidated.

The balance of concurrent aggregation and deaggregation processes in platelets is linked to differential occupancy of ADP receptor subtypes.

Deaggregation, the partial reversal of the initial aggregation of platelets is observed following low, but not higher, micromolar ADP concentrations. This study tested the hypothesis that deaggregation results from a balance between concurrent, opposing, aggregation and deaggregation processes which are ADP (adenosine 5'-diphosphate) receptor occupancy-dependent. Aggregation of human platelet-rich plasma (PRP) prepared in r-hirudin was assayed in a 96-well plate reader over 20 min by measurement of the optical density (OD) at 580 nm.

Novel actions of inverse agonists on 5-HT2C receptor systems.

In cell systems where ligand-independent receptor activity is optimized (such as when receptors are overexpressed or mutated), acute treatment with inverse agonists reduces basal effector activity whereas prolonged exposure leads to sensitization of receptor systems and receptor up-regulation. Few studies, however, have reported effects of inverse agonists in systems where nonmutated receptors are expressed at relatively low density. Here, we investigated the effects of inverse agonists at human serotonin (5-HT)2C receptors expressed stably in Chinese hamster ovary cells ( approximately 250 fmol/mg protein).

Interactions between effectors linked to serotonin receptors.

In general, there are two types of interactions between effector signaling pathways. "Homologous" interactions are those that occur within a receptor system to alter its own responsiveness, for example the loss of responsiveness (desensitization) that can occur upon agonist occupancy of a receptor. "Heterologous" interactions are those that occur between different receptor systems where the responsiveness of one receptor system is regulated (positively or negatively) by activation of another receptor system (i.

Pleiotropic behavior of 5-HT2A and 5-HT2C receptor agonists.

There is now considerable evidence that a single receptor subtype can couple to multiple effector pathways within a cell. Recently, Kenakin proposed a new concept, termed "agonist-directed trafficking of receptor stimulus", that suggests that agonists may be able to selectively activate a subset of multiple signaling pathways coupled to a single receptor subtype. 5-HT2A and 5-HT2C receptors couple to phospholipase C-(PLC) mediated inositol phosphate (IP) accumulation and PLA2-mediated arachidonic acid (AA) release.