53 research outputs found

    The typology of connectivity in landscape architecture: a review of studies on landscape connectivity (LC)

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    Connectivity is an important landscape characteristic that is essential for health, welfare and aesthetic values in human societies as well as for the protection of native ecosystems. Diversity in objectives, approaches, definitions and methods in studies on connectivity and its widespread use in the field of landscape ecology are reasons why Landscape Connectivity (LC) in landscape architecture has been deemed as the counterpart of Ecological Connectivity leading to neglect of other aspects of this comprehensive concept. This study, reviews and classifies studies carried out in the field of landscape with a focus on connectivity in order to achieve a comprehensive definition of LC and its various components in landscape architecture literature. The research method used in this study was quantitative-qualitative. In the first phase, the literature was collected using library research and internet search via a descriptive-analytical approach. Then, an inductive constructionist strategy using Delphi technique was used to classify and categorize relevant studies, and logical argumentation was used to develop the concept of LC in landscape architecture literature. Finally, the objectivist Descriptive/Synthetic Modelling strategy was used to provide a conceptual model of urban landscape connectivity (ULC). The key finding of this study is the researcher-made conceptual model of ULC, its corresponding components and parameters with the viewpoint of landscape architecture

    Triggered optical coherence tomography for capturing rapid periodic motion

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    Quantitative cross-sectional imaging of vocal folds during phonation is potentially useful for diagnosis and treatments of laryngeal disorders. Optical coherence tomography (OCT) is a powerful technique, but its relatively low frame rates makes it challenging to visualize rapidly vibrating tissues. Here, we demonstrate a novel method based on triggered laser scanning to capture 4-dimensional (4D) images of samples in motu at audio frequencies over 100 Hz. As proof-of-concept experiments, we applied this technique to imaging the oscillations of biopolymer gels on acoustic vibrators and aerodynamically driven vibrations of the vocal fold in an ex vivo calf larynx model. Our results suggest that triggered 4D OCT may be useful in understanding and assessing the function of vocal folds and developing novel treatments in research and clinical settings

    Surface profiling of object using varifocal lens with image contrast

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    The measurement of automated and fast focusing on the improvement of speed and accuracy is an important issue in industrial inspection and biomedical microscopy. In this study, we developed a novel optical imaging system in which varifocal lenses are used to characterize the 3D surface topography of samples. The performance of the proposed system was evaluated using twelve focusing algorithms. Experimental results demonstrate the feasibility and effectiveness of the proposed system in the near real-time construction of multi-focus fusion images with large depth of field from which to derive 3D surface profiles

    Restless legs syndrome in hemodialysis patients in Iran

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    Restless legs syndrome (RLS) is a common sleep disorder that can present secondary to medical conditions such as renal failure. This study aimed to evaluate RLS frequency and its related factors in chronic renal failure patients treated with hemodialysis. In a cross-sectional design, 163 patients with chronic renal failure were consecutively enrolled from hemodialysis center at Rasool-Akram hospital. Demographics, clinical and laboratory data were recorded. Patients were screened for presence and severity of RLS according to the four International Restless Legs Syndrome Group (IRLSSG) diagnostic criteria and severity scale. Patients with and without RLS were compared using SPSS statistical software (Version 16.0). Sixty-one patients (37.4 ) were diagnosed with RLS. Mean age in RLS group was significantly higher (65.2 ± 9.3 years) than RLS-negative group (59.0 ± 14.7 years; P = 0.004). Serum creatinine level was significantly higher in patients with RLS (7.6 ± 2.1 mg/dl vs. 6.7 ± 1.8 mg/dl; P = 0.009). Glomerular filtration rate in RLS patients was lower than other patients (9.2 ± 3.1 ccs/min vs. 11.6 ± 4.8 ccs/min; P = 0.0001). Patients with RLS had shorter sleep duration, and higher incidence of insomnia, daytime sleepiness, and sedative-hypnotic medication usage (P < 0.05). There was no significant difference between RLS-positive and RLS-negative patients in terms of renal failure pathology, dialysis frequency per week, dose of dialysis, duration of dialysis, renal transplantation, and history of diabetes and hypertension. Hemodialysis patients have a high prevalence of RLS which deserves special attention and specific treatment. © 2014, Springer-Verlag Italia

    Velocity-estimation accuracy and frame-rate limitations in color Doppler optical coherence tomography

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    Color Doppler optical coherence tomography (CDOCT) is a recent innovation that allows spatially localized flow-velocity mapping simultaneously with microstructural imaging. We present a theoretical model for velocity-image formation in CDOCT. The proportionality between the heterodyne detector current Doppler power spectrum in CDOCT and the optical source power spectrum is established. We show that stochastic modifications of the Doppler spectrum by fluctuating scatterer distributions in the flow field give rise to unavoidable velocity-estimation inaccuracies as well as to a fundamental trade-off between image-acquisition rate and velocity precision. Novel algorithms that permit high-fidelity depth-resolved measurements of velocities in turbid media are also reporte

    High-flow-velocity and shear-rate imaging by use of color Doppler optical coherence tomography

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    Color Doppler optical coherence tomography (CDOCT) is capable of precise velocity mapping in turbid media. Previous CDOCT systems based on the short-time Fourier transform have been limited to maximum flow velocities of the order of tens of millimeters per second. We describe a technique, based on interference signal demodulation at multiple frequencies, to extend the physiological relevance of CDOCT by increasing the dynamic range of measurable velocities to hundreds of millimeters per second. The physiologically important parameter of shear rate is also derived from CDOCT measurements. The measured flow-velocity profiles and shear-rate distributions correlate very well with theoretical predictions. The multiple demodulation technique, therefore, may be useful to monitor blood flow in vivo and to identify regions with high and low shear rate
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