Frequency estimation precision in Doppler optical coherence tomography using the Cramer-Rao lower bound

Doppler optical coherence tomography (DOCT) is a technique for simultaneous cross-sectional imaging of tissue structure and blood flow. We derive the fundamental uncertainty limits on frequency estimation precision in DOCT using the Cramer-Rao lower bound in the case of additive (e.g., thermal, shot) noise. Experimental results from a mirror and a scattering phantom are used to verify the theoretical limits. Our results demonstrate that the stochastic nature of frequency noise influences the precision of flow imaging, and that the noise model must be selected judiciously in order to estimate the frequency precision

Walking through architectural spaces: The impact of interior forms on human brain dynamics

© 2017 Banaei, Hatami, Yazdanfar and Gramann. Neuroarchitecture uses neuroscientific tools to better understand architectural design and its impact on human perception and subjective experience. The form or shape of the built environment is fundamental to architectural design, but not many studies have shown the impact of different forms on the inhabitants’ emotions. This study investigated the neurophysiological correlates of different interior forms on the perceivers’ affective state and the accompanying brain activity. To understand the impact of naturalistic three-dimensional (3D) architectural forms, it is essential to perceive forms from different perspectives. We computed clusters of form features extracted from pictures of residential interiors and constructed exemplary 3D room models based on and representing different formal clusters. To investigate human brain activity during 3D perception of architectural spaces, we used a mobile brain/body imaging (MoBI) approach recording the electroencephalogram (EEG) of participants while they naturally walk through different interior forms in virtual reality (VR). The results revealed a strong impact of curvature geometries on activity in the anterior cingulate cortex (ACC). Theta band activity in ACC correlated with specific feature types (rs (14) = 0.525, ρ = 0.037) and geometry (rs (14) = –0.579, ρ = 0.019), providing evidence for a role of this structure in processing architectural features beyond their emotional impact. The posterior cingulate cortex and the occipital lobe were involved in the perception of different room perspectives during the stroll through the rooms. This study sheds new light on the use of mobile EEG and VR in architectural studies and provides the opportunity to study human brain dynamics in participants that actively explore and realistically experience architectural spaces

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

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

Effect of physical dimensions of classroom on Promotion of Active Participation in the Learning Process

The existing educational space in schools has been accused of assuming a passive role for children and creating negative effects on their mental development. Although this educational environment initially paved the way for introducing the modern educational program, it lacked the required ability to mobilize and activate a child’s mind, and create motivation for learning. Due to the significance of active learning, its effective elements are first described in this study. From among the 3 effective elements in active learning, “participation” was selected. Subsequently, the effective factors on a child’s participation in the learning process were determined in the form of two models, namely, the social model and the activity model. The research typology is a quantitative method through a surveying study The theoretical content analysis method was used to classify the different perspectives and the interview and observation method was implemented for the selected case study. The objective of this study is to examine the effect of class room size on the students’ participation in the learning process. The statistical population of this study was the middle school children in Bojnourd, Iran, in the 2014-2015 academic year. Subsequently, 279 students were randomly selected from among the above population for completing the questionnaire.  The results showed that the majority of the students preferred smaller classrooms, therefore, the overall conclusion in this study is that, to promote participation in the learning process, the following criteria must be considered in designing closed educational spaces: 1) socialization; 2) individual and group activity, and 3) involvement and experience in learning

Social network sites as educational factors

Background: In this present era, the technology development has established certain type of communication. Nowadays education as the fundamental principle in transferring cognition to the learners has found various methods. Recently the concept that social networks could be effective tool in easing the achievement to the educational goals has been under attention. Therefore, this investigation is trying to find out whether, the social networks could play role on the process of education among students? Materials and Methods: This cross sectional descriptive study was performed on 1000 students from 7 medical universities in 2015. The data collection tool was questionnaire that was approved Cronbach's alpha was 0.85. Meanwhile its validity was confirmed too. The obtained data were analyzed by the descriptive statistic, ANOVA, Turkey and used X2 SPSS-19. Results: In this investigation, 940 subjects were under study. 85 used daily the social network. The highest usage was attributed to the Telegram. 52 preferred image suitable for transferring of information. Even though, 73 believed that these networks have significant effects on coordinating of students with in university charges. Conclusion: Considering the findings of the present study, it is proposed that the universities integrate the social networks in the education programs and recognize it as the awareness factor, therefore benefit it in the educational affairs. © 2016 Alireza Ebrahimpour, Farnaz Rajabali, Fatemeh Yazdanfar, Reza Azarbad, Majid Rezaei Nodeh, Hasan Siamian, Mohammad Vahedi

Fluorescent Silicon Clusters and Nanoparticles

The fluorescence of silicon clusters is reviewed. Atomic clusters of silicon have been at the focus of research for several decades because of the relevance of size effects for material properties, the importance of silicon in electronics and the potential applications in bio-medicine. To date numerous examples of nanostructured forms of fluorescent silicon have been reported. This article introduces the principles and underlying concepts relevant for fluorescence of nanostructured silicon such as excitation, energy relaxation, radiative and non-radiative decay pathways and surface passivation. Experimental methods for the production of silicon clusters are presented. The geometric and electronic properties are reviewed and the implications for the ability to emit fluorescence are discussed. Free and pure silicon clusters produced in molecular beams appear to have properties that are unfavourable for light emission. However, when passivated or embedded in a suitable host, they may emit fluorescence. The current available data show that both quantum confinement and localised transitions, often at the surface, are responsible for fluorescence. By building silicon clusters atom by atom, and by embedding them in shells atom by atom, new insights into the microscopic origins of fluorescence from nanoscale silicon can be expected.Comment: 5 figures, chapter in "Silicon Nanomaterials Sourcebook", editor Klaus D. Sattler, CRC Press, August 201

Molecular contrast in optical coherence tomography using a pump-probe technique and a optical switch suppression technique

We describe two novel techniques for contrast enhancement in optical coherence tomography (OCT) which enables molecular specific imaging. The first, a pump-probe technique, is employed in which a pulsed pump laser is tuned to ground-state absorption in a molecule of interest. The location of the target molecule population is derived from the resulting transient absorption of OCT sample arm light acting as probe light. Preliminary results exhibiting contrast enhancement in cross-sectional OCT images using methylene blue dye are presented. The second method is an optical switch suppression technique based on the use of a transmembrane protein called bacteriorhodopsin. Initial experiments indicate that biochemical optical switches, such as bacteriorhodopsin, are excellent contrast agent candidates for molecular contrast OCT

Molecular contrast in optical coherence tomography using a pump-probe technique and a optical switch suppression technique

We describe two novel techniques for contrast enhancement in optical coherence tomography (OCT) which enables molecular specific imaging. The first, a pump-probe technique, is employed in which a pulsed pump laser is tuned to ground-state absorption in a molecule of interest. The location of the target molecule population is derived from the resulting transient absorption of OCT sample arm light acting as probe light. Preliminary results exhibiting contrast enhancement in cross-sectional OCT images using methylene blue dye are presented. The second method is an optical switch suppression technique based on the use of a transmembrane protein called bacteriorhodopsin. Initial experiments indicate that biochemical optical switches, such as bacteriorhodopsin, are excellent contrast agent candidates for molecular contrast OCT