241 research outputs found
Sparse MRI and CT Reconstruction
Sparse signal reconstruction is of the utmost importance for efficient medical imaging, conducting accurate screening for security and inspection, and for non-destructive testing. The sparsity of the signal is dictated by either feasibility, or the cost and the screening time constraints of the system. In this work, two major sparse signal reconstruction systems such as compressed sensing magnetic resonance imaging (MRI) and sparse-view computed tomography (CT) are investigated.
For medical CT, a limited number of views (sparse-view) is an option for whether reducing the amount of ionizing radiation or the screening time and the cost of the procedure. In applications such as non-destructive testing or inspection of large objects, like a cargo container, one angular view can take up to a few minutes for only one slice. On the other hand, some views can be unavailable due to the configuration of the system. A problem of data sufficiency and on how to estimate a tomographic image when the projection data are not ideally sufficient for precise reconstruction is one of two major objectives of this work. Three CT reconstruction methods are proposed: algebraic iterative reconstruction-reprojection (AIRR), sparse-view CT reconstruction based on curvelet and total variation regularization (CTV), and sparse-view CT reconstruction based on nonconvex L1-L2 regularization. The experimental results confirm a high performance based on subjective and objective quality metrics. Additionally, sparse-view neutron-photon tomography is studied based on Monte-Carlo modelling to demonstrate shape reconstruction, material discrimination and visualization based on the proposed 3D object reconstruction method and material discrimination signatures.
One of the methods for efficient acquisition of multidimensional signals is the compressed sensing (CS). A significantly low number of measurements can be obtained in different ways, and one is undersampling, that is sampling below the Shannon-Nyquist limit. Magnetic resonance imaging (MRI) suffers inherently from its slow data acquisition. The compressed sensing MRI (CSMRI) offers significant scan time reduction with advantages for patients and health care economics. In this work, three frameworks are proposed and evaluated, i.e., CSMRI based on curvelet transform and total generalized variation (CT-TGV), CSMRI using curvelet sparsity and nonlocal total variation: CS-NLTV, CSMRI that explores shearlet sparsity and nonlocal total variation: SS-NLTV. The proposed methods are evaluated experimentally and compared to the previously reported state-of-the-art methods. Results demonstrate a significant improvement of image reconstruction quality on different medical MRI datasets
Offine/online Optimum Routing of a UAV using Auxiliary Points
This paper presents a method to determine the route of a three-dimensional UAV. Three criteria; the height, the length of flight path and the unauthorized areas are used as the constraints and combined in a fuzzy function as the evaluation function. The article aimed to discover a minimum cost route from source to destination considering the constrains. In this paper a new searching method is proposed, with use of auxiliary points. The auxiliary point method iteratively divides a straight line to two shorter lines with less cost of evaluation function. Implementation results show that the proposed method dramatically decreases the calculations; meanwhile the ight route is sub-optimum
Maintaining health and sustainability of urban metabolism ecosystem in line with sustainable development: a case study of Qarchak, Iran
Background: The present study aimed to evaluate the urban metabolism in line with sustainable development of Qarchak city, Iran.
Methods: The present study was applied in terms of type and descriptive-analytical in terms of method. The statistical population of the study included Qarchak city as one of the cities of Tehran province with a population of 231075 people based on 2016 census. It is located in the northwest of Varamin city. Information was collected through library studies, documents and databases were checked. After identifying the criteria, they were converted into quantitative indices and the indices were weighted and prioritized within the framework of AHP weight model. Data analysis was done with the Metabolic Outcomes Assessment (MIA) method.
Results: The final score of the study area was 29.61, while the optimal status is 60.64. Therefore, the current status of the area compared to the optimal status, gained about 45% of the scores. It indicates that the metabolic status of the study area is poor. Also, according to experts, water criterion with a weight of 0.388 has the highest rank and air criterion with a weight of 0.075 has the lowest rank and importance. Also, the incompatibility coefficient is 0.09, which is acceptable.
Conclusion: Based on the results of the present study, understanding the deep relationship between the city and the environment to solve urban and environmental problems, optimization of systems and multiple natural and human processes is essential that should be considered by public people and urban planners
Daylight Parameters and Operation Quality Case Studies: Public Office Buildings in Kerman, Iran
Most of existing government office building in Iran were designed and built without enough consideration to the daylight design. Therefore a lot of electricity energy should be used to provide visual comfort in office rooms in government office buildings. Due to location of Kerman City of Iran, There are a lot of solar radiation in whole year during working hours in exterior spaces. In this research daylight quality of 4 office rooms in 2 government office buildings in Kerman city of Iran were investigated through experimental measurement and calculating some daylight parameters such as mean Work PlaneIlluminance (WPI), Work Plane Illuminance Ratio (WPI Ratio) and daylight Ratioin two conditions when lights were on and off. Finding of this research reveals that most of office building in government building cannot reach the acceptable range of different parameters of daylight even though lights were on. Therefore research about daylight quality in office rooms in this region is an important issue to be investigated to find different methods and solutions for improving daylight quality in office rooms. Keywords: Daylight Quality, Government Office buildings, Working Plane Illuminance, Working Plane Illuminance Ratio, Daylight Facto
Biophysical and biochemical characterization of proteins involved in a-glucan biosynthesis in mycobacteria
A capsule composed of mainly α-glucan forms the most outermost layer of cell envelope of Mycobacterium tuberculosis, the causing agent of tuberculosis. Capsule participates in modulating the immune system responses. In GlgE pathway, one of the three pathways involved in α-glucan synthesis, trehalose in converted to glucan through the activity of four enzymes, trehalose synthase, maltokinase Pep2, maltosyltransferase GlgE and branching enzyme GlgB. It has shown that M. tuberculosis TreS and Pep2 form an octameric complex together. During this study we solved the structure of the complex at 3.6 Å in M. smegmatis. The structure reveals two pairs of Pep2 monomers bind to the opposite sides of the diamond shaped TreS tetramer in a 4 + 4 complex. However, studying the stoichiometry of the complex using other techniques such as: ITC, AUC and SAXS indicates a 4 + 2 complex formation in the solution. Moreover, our data using size exclusion chromatography would suggest that this complex formation is pH dependent and favors complex formation at more acidic pHs. This study is a step forward towards better understanding of the capsule synthesis in M. tuberculosis and highlights the role of complex formation between enzymes as an effective strategy to control the metabolic pathways in mycobacteria
Lymphatic mapping and sentinel node biopsy in a patient with upper limb Merkel Cell Carcinoma: a case report and brief review of literature
Sentinel node mapping is an integral part of regional lymph node staging in many solid tumors and plays an important role in surgical oncology. This technique has been used with excellent results for non-melanoma skin cancers including Merkel Cell Carcinoma (MCC). In the current study, we reported our first MCC patient who underwent successful sentinel node mapping. We also reviewed the available literature regarding the prognostic significance of sentinel node mapping in cN0 MCC patients.Sentinel node mapping is an integral part of regional lymph node staging in many solid tumors and plays an important role in surgical oncology. This technique has been used with excellent results for non-melanoma skin cancers including Merkel Cell Carcinoma (MCC). In the current study, we reported our first MCC patient who underwent successful sentinel node mapping. We also reviewed the available literature regarding the prognostic significance of sentinel node mapping in cN0 MCC patients
Design and performance evaluation of a prototype MRF-based haptic interface for medical applications
This paper describes the construction and stability and transparency evaluation of a prototype two degrees-of-freedom (DoF) haptic interface, which takes ad-vantage of magneto-rheological fluid (MRF)-based clutches for actuation. These small-scale clutches were designed in our lab, and their evaluation were reported previously [1],[2]. MRF-based actuators exhibit superior characteristics,which can significantly contribute to transparency and stability of haptic devices. Based on these actuators, a distributed antagonistic configuration is used to develop the2-DoF haptic interface. This device is incorporated in a master–slave teleoperation setup intended for medical per-cutaneous interventions and soft-tissue palpation. Preliminary studies on the stability and transparency of the haptic interface in this setup using phantom and ex vivo samples show the great potential of MRF-based actuators for integr-tion in haptic devices that require reliable, safe, accurate,highly transparent, and stable force reflection
Computational vs. qualitative: analyzing different approaches in identifying networked frames during the Covid-19 crisis
Despite the increasing adaption of automated text analysis in communication studies, its strengths and weaknesses in framing analysis are so far unknown. Fewer efforts have been made to automatic detection of networked frames. Drawing on the recent developments in this field, we harness a comparative exploration, using Latent Dirichlet Allocation (LDA) and a human-driven qualitative coding process on three different samples. Samples were comprised of a dataset of 4,165,177 million tweets collected from Iranian Twittersphere during the Coronavirus crisis, from 21 January, 2020 to 29 April, 2020. Findings showed that while LDA is reliable in identifying the most prominent networked frames, it misses to detects less dominant frames. Our investigation also confirmed that LDA works better on larger datasets and lexical semantics. Finally, we argued that LDA could give us some primary intuitions, but qualitative interpretations are indispensable for understanding the deeper layers of meaning
The Effect of Clearance on the Performance of Machine Husking Rubber Rolls for Two
تاثير الخلوص بين الاسطوانات لنوع الماكنة Yanmar rubber roll- ST 50 على نوعية تقشير الرز ونسبة التكسر لتقييم صنفين من الرز تارم هاشمي وديلماني والخلوص بين الاسطوانات لمكائن التقشير تحت ثلاث مستويات مختلفة 0.4,0.6 و 0.8 ملم. باستخدام تصميم التجربة CRD وبثلاث مكررات اظهرت النتائج تفوق صنف الرز تارم هاشمي معنويا على صنف الرز ديلماني في جميع الصفات المدروسة. كانت هناك علاقة ايجابية بين زيادة الخلوص على نسبة الحبة الكاملة والرز الخام وعلاقة سلبية مع زيادة نسبة الحبوب المتشققة والتكسر وكفاءة التقشير .The effect of clearance between cylinders of machine husking rubber rolls (type Yanmar rubber roll – ST 50) on rice husk quality and breakage percentage was evaluated for two cultivars of rice. Tarm Hashemi (TH) and Daillman (DM) and clearance between cylinders of machine husking rubber at three different levels of 0.4, 0.6 and 0.8mm.The experiment was done in factorial experiment under complete randomized design (CRD) with three replications the results indicate that the TH cultivar is significantly better than the D M in all studied traits. There was a negative relationship between increased clearance with head rice percentage and brown rice percentage in addition to the positive relationship between the increased percentage of cracked grain ,broken rice percentage and husking efficiency
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