Role and applications of circulatory models in cardiovascular pathophysiology.

Circulatory models are relevant for research, education and prosthetic devices/components testing. Independently of its structure that can be numerical, physical or hybrid, the models can be used in different areas of cardiovascular pathophysiology. However, the models are often used to reproduce specific circulatory conditions instead of being used as "systemic" tools. That is to say, the models are used to evaluate the global effects of external disturbances such as pathologies, therapies, special environments or surgery on the circulatory system. Aim of this paper is to illustrate a family of circulatory models developed to represent the whole circulatory system in pathophysiological conditions describing some of the possible applications

“Supposing that truth is a woman, what then?” The Lie Detector, The Love Machine and the Logic of Fantasy

One of the consequences of the public outcry over the 1929 St Valentine’s Day massacre was the establishment of a Scientific Crime Detection Laboratory at Northwestern University. The photogenic “Lie Detector Man”, Leonarde Keeler, was the Laboratory’s poster boy and his instrument the jewel in the crown of forensic science. The press often depicted Keeler gazing at a female suspect attached to his “sweat box”; a galvanometer electrode in her hand, a sphygmomanometer cuff on her arm and a rubber pneumograph tube strapped across her breasts. Keeler’s fascination with the deceptive charms of the female body was one he shared with his fellow lie detector pioneers, all of whom met their wives – and in William Marston’s case his mistress too – through their engagement with the instrument. Marston employed his own “Love Meter”, as the press dubbed it, to prove that “brunettes react far more violently to amatory stimuli than blondes”. In this paper I draw on the psychoanalytic concepts of fantasy and pleasure to argue that the female body played a pivotal role in establishing the lie detector’s reputation as an infallible and benign mechanical technology of truth

EtCO₂ -Based Biofeedback Method of Breath Regulation Increases Speech Fluency of Stuttering People

Respiratory disturbances frequently accompany stuttering. Their influence on lung ventilation can be assessed by measurement of the end-tidal CO2 concentration (EtCO2). The effectiveness of the CO2-based visual feedback method of breath regulation (VF) designed for stuttering therapy was tested in this study. The aim of the study was to answer the question if the VF helps to reduce respiratory disturbances in stuttering and increase speech fluency. 20 stuttering volunteers aged 13–45 years took part in the 3-parts test consisting of: 1. speaking without any techniques improving speech fluency, 2. learning the VF method, 3. VF-assisted speaking. The CO2/time signal and an acoustic signal of an utterance were recorded during the test. Significant increase of FE – the factor of breath ergonomics during speaking (based on both signals), from 47% to 71% (P < 0.01), and significant decrease of %SS – the percent of syllables stuttered, from 14% to 10% (P < 0.01) were received for VF-assisted utterances compared to the utterances without VF assistance. The results indicate that the VF can help to eliminate respiratory disturbances in stuttering and increase speech fluency

The growth and structure of titanium dioxide films on a Re 10 10 surface Rutile 011 2x1

Titanium dioxid films were grown on Re 10 10 by Ti vapor deposition in oxygen at T 830 K and studied by means of low energy electron diffraction LEED , X ray photoelectron spectroscopy XPS , low energy ion scattering LEIS and X ray diffraction XRD . The Ti oxid stoichiometry was determined by XPS as Ti O 1 2, with the Ti oxidation state 4 . The TiO2 growth was monitored by means of LEED as a function of film thickness. Extending the coverage from the submonolayer into the multilayer regime gives rise to a p 2x2 pattern, a poorly ordered 1x1 , and, finally, a stable 2x2 structure, the latter being associated with a homogeneous TiO2 phase. For normal electron incidence, the 2x2 LEED pattern exibits systematically extinguished beams at n 1 2,0 positions, indicating a glide mirror plane. The pg 2x2 structure could be explained by both a rutile 011 2x1 reconstructed surface and a bulk truncated brookite 001 surface. Faceting phenomena, i.e. running LEED spots, observed with thin TiO2 films point to the formation of a rutile 011 2x1 surface with two domains and 011 2x1 facets and rule out the brookite alternative. Confirmation of this assignment was obtained by an XRD analysis perfomed at the Berlin synchrotron facility BESS

Identification of a buried single quantum well within surface structured semiconductors using depth resolved x-ray grazing incidence diffraction

A free standing surface wire nanostructure defined on GaAs[001] containing a 5 nm thick GaInAs single quantum well (SQW) was analysed, recording reciprocal space maps by coplanar high-resolution x-ray diffraction (HRXRD) and non-coplanar x-ray grazing incidence diffraction (GID). We were able to evaluate the depth and the thickness of the SQW by depth resolved GID via computer simulations based on a kinematic approach. The identification of the SQW was possible exploiting the large scattering contrast between GaAs and GaInAs at the (200) in-plane Bragg reflection. For HRXRD the nearly rectangular shaped wires directed along [110] give the main contribution to the intensity map in reciprocal space whereas the SQW itself is not visible. This demonstrates that combined HRXRD and GID reciprocal space maps provide an entire 3D analysis of surface nanostructures

Evaluation of strain distribution in freestanding and buried lateral nanostructures

A free-standing lateral nanostructure based on GaAs[001] containing a Ga0.97In0.03As single quantum well and similar structures after the overgrowth with GaAs and AlAs, respectively, have been investigated by high-resolution x-ray grazing incidence diffraction (GID) and conventional x-ray diffraction (HRXRD). The wire shape of the freestanding structure and the lateral density variation in the overgrown samples, were determined by running scans with constant length of the scattering vector (transverse scans) across the grating truncation rods (GTR’s) close to the (2¯20) reflection. The in-plane strain distribution became available crossing the (220) GTR’s by a scan in the longitudinal direction. Exploiting the capability of GID for depth resolution, the in-plane strain distribution was analyzed for different values of depth below the sample surface. The strain analysis was completed by HRXRD measurements close to the (004) reflection. The x-ray measurements were interpreted in terms of the distorted wave Born approximation applied for GID geometry. The strain distribution is determined by comparing the measured GTR intensities with the corresponding simulations containing the displacement fields obtained from finite-element calculations. At the freestanding wire structure we find laterally compressive strain of about Δa/a∥=−2×10−3 at the single quantum well (SQW) with a steep strain gradient close to the wire side walls. Both overgrown samples show pronounced lateral strain variation within the overgrown layer, which still appears up to the completely planar surface. Within the SQW the in-plane strain is still compressive after GaAs overgrowth and of similar amount compared to the freestanding grating. The strain is increased by about 30% after overgrowth with AlAs. For both overgrown samples the strain gradient near the wire side walls is reduced, but reaches a maximum close to the SQW. Accompanied by the defect passivation, these findings explain the difference in the energy shift of the photoluminescence line between freestanding and overgrown lateral nanostructures

A hybrid (hydro-numerical) circulatory model: investigations of mechanical aortic valves and a numerical valve model

In most cases of diseased heart valves, they can be repaired or replaced with biological or mechanical prostheses. Biological prostheses seem to be safer than mechanical ones and are applied with good clinical outcomes. Their disadvantage, when compared with mechanical valves, is durability. In the development and application of mechanical and biological heart valves, a significant role can be played by a Hybrid (Hydro-Numerical) Circulatory Model. The aim of this paper is to demonstrate the opportunities created by the hybrid model for investigations of mechanical heart valves and their computer models under conditions similar to those of the circulatory system. A diode-resistor numerical valve model and three different design mechanical aortic valves were tested. To perform their investigations, computer applications were developed under RT LabView to be run on a PC. Static and dynamic characteristics of the valves were measured and registered - pressure in the numerical time-varying elastance left ventricle (pLV), in the aorta (pas) and flow (f), proving, among other factors, that 1) time delay of pas with respect to pLV is mainly related to the valve’s opening time, and 2) the valves of substantially different designs tested under identical hydrodynamic conditions reveal nearly the same dynamic performance