Search results for "Optica"

<title>Photonic vascular diagnostics by four-channel photoplethysmography</title>

2005

A four-channel photoplethysmography device was designed and built at University of Latvia to detect signals from different body parts and to analyze the signal shapes. The device consists of optical contact probes, interface, and a standard PC. Clinical tests were performed with occlusion patients having vascular problems at arm or leg arteries. Results showed significant difference in the pulse wave transit time in occluded and nonoccluded part of the body.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Influence of heterogeneous freezing on the microphysical and radiative properties of orographic cirrus clouds

2013

The influence of heterogeneous freezing on the microphysical and optical properties of orographic cirrus clouds has been simulated with the large eddy simulation model EULAG. Idealised simulations with different concentrations of ice nuclei (IN) in a dynamically dominated regime with high vertical velocities have been performed. Furthermore the temperature at cloud formation as well as the critical supersaturation for initiation of heterogenous freezing have been varied. The shortwave, longwave and net cloud forcing has been calculated under the assumption that the clouds form between 06:00 and 12:00 local time (LT) or between 12:00 and 18:00 LT. In general it can be seen that the onset of …

Bimodal drop size distributions during the early stages of shear induced coalescence

2005

Drop sizes and drop size distributions were determined by means of an optical shear cell in combination with an optical microscope for the systems polyisobutylene/poly(dimethylsiloxane) (I) and poly(dimethyl-co-methylphenylsiloxane)/poly(dimethylsiloxane) (II) at low concentrations of the suspended phases and at different constant shear rates ranging from 10 to 0.5 s-1 . After pre-shearing the two-phase mixtures (I: 50 s-1; II: 100 s-1) for the purpose of producing small drop radii, the shear rate was abruptly reduced to the preselected value and coalescence was studied as a function of time. In all cases one approaches dead end drop radii, i.e. breakup is absent. The drop size distribution…

Morphology of PEO/PDMS blends during shear: Coexistence of two droplet/matrix structures and additive effects

2005

Abstract The morphologies of blends of polyethyleneoxide (PEO 37) and poly(dimethylsiloxane)s (PDSM), with viscosity ratios, λ , of approximately one (PDMS 230) or 2.8 (PDMS 314, being the component of higher viscosity) and interfacial tensions on the order of 10 mN/m, were investigated at 70 °C as a function of shear rate (up to 10 s −1 ) and of time. For the system PEO 37/PDMS 230 we have also studied the influence of the compatibilizer dimethyl–ethyleneoxide–copolymer (PDMS- co -PEO), which is only reasonably soluble in PEO. To investigate the morphologies we have used an optical shear cell in combination with a light microscope. The most important observation consists in the formation o…

On the Role of Drop Break Up for Coalescence Processes and Morphology Development in Polymer Blends under Shear

2005

Drop sizes and drop-size distributions were determined as a function of time at constant shear rates, γ, by means of an optical shear cell in combination with an optical light microscope after preshearing the samples at high γ. The systems under investigation were PIB 3/PDMS 152 (PIB:  polyisobutylene, PDMS:  poly(dimethylsiloxane), numbers:  average molar masses in kg/mol) and COP 26*/PDMS 48 (COP:  poly(dimethyl-co-methylphenylsiloxane), asterisk:  apparent molar mass); all measurements refer to 25 °C. Systems and conditions were chosen such that shear rates in the vicinity of the intersection of the coalescence and the break up curves become experimentally accessible. Under these conditi…

Statistical mechanics of fullerene coalescence growth

2006

Among the different carbon allotropes fullerenes are exceptionally intriguing for their spheroidal topology out of pentagons and hexagons. However, the dominant formation mode is still ambiguous. Here, we analyze the fullerene formation process by the statistical analysis of fullerene sizes produced in a laser-induced microplasma finding that a simple two-parameter lognormal distribution describes impressively well the cluster frequencies under various conditions. Our findings clearly reveal coalescent growth following a classical collision dynamics and disagree with several earlier assumptions.

Concepts of All-Optical Physiology

2017

Perceptual semantics: A three-level approach

2010

In this work we suggest a model according to which semantics has been already generated during the perception through the interaction of three dynamic levels of perceptual organization. We consider perceptual grouping as the first order processing. Shape formation is considered as the second order processing. Both grouping and shape formation can be considered as two complementary and interrelated processes of perceptual organization. The third — partially overlapping — level is meaning assignment. Most of the results are supported by empirical evidence based on new visual illusions of shape and meaning and are consistent with several other proposals (e.g., [1], [2] and [3]).

Unveiling anion-induced folding in tripodal imidazolium receptors by ion-mobility mass spectrometry.

2021

The anion-induced folding of tripodal imidazolium receptors has been investigated by NMR spectroscopy, electrospray ionization ion mobility mass spectrometry and DFT calculations. Such folding can be switched by anion release upon collision induced dissociation.

Evidence of Spatially Inhomogeneous Electron Temperature in a Resonantly Excited Array of Bow-Tie Nanoantennas

2019

We studied the excitation of large-area Au bow-tie nanoantenna arrays, which we have fabricated on indium-tin-oxide (ITO)-coated glass substrates using colloidal lithography with nanoscale polystyr...