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CT theory and use

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https://www.readbyqxmd.com/read/28448902/surface-modified-tio2-nanoparticles-with-ascorbic-acid-antioxidant-properties-and-efficiency-against-dna-damage-in-vitro
#1
Vladan Bajić, Biljana Spremo-Potparević, Lada Živković, Andrea Čabarkapa, Jelena Kotur-Stevuljević, Esma Isenović, Dušan Sredojević, Ivana Vukoje, Vesna Lazić, S Phillip Ahrenkiel, Jovan M Nedeljković
The antigenotoxic and antioxidative properties of surface-modified TiO2 nanoparticles (NPs) with ascorbic acid (AA) were compared with those of constituents (free AA and bare TiO2 NPs). Colloids consisting of the TiO2 NPs with anatase crystal structure were prepared by acidic hydrolysis of TiCl4. The synthesized TiO2 NPs were characterized using transmission electron microscopy and X-ray diffraction analysis. The charge transfer (CT) complex formation between surface Ti atoms and AA is indicated by immediate appearance of red color...
April 14, 2017: Colloids and Surfaces. B, Biointerfaces
https://www.readbyqxmd.com/read/28436852/frequency-selective-computed-tomography-applications-during-periodic-thoracic-motion
#2
Jacob Herrmann, Eric A Hoffman, David W Kaczka
We seek to use computed tomography (CT) to characterize regional lung parenchymal deformation during highfrequency and multi-frequency oscillatory ventilation. Periodic motion of thoracic structures results in artifacts of CT images obtained by standard reconstruction algorithms, especially for frequencies exceeding that of the X-ray source rotation. In this study, we propose an acquisition and reconstruction technique for high resolution imaging of the thorax during periodic motion. Our technique relies on phase-binning projections according to the frequency of subject motion relative to the scanner rotation, prior to volumetric reconstruction...
April 18, 2017: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28426947/structural-neuroplasticity-of-the-superior-temporal-plane-in-early-and-late-blindness
#3
Hicret Atilgan, Olivier Collignon, Uri Hasson
Blindness is associated with well-documented changes to the morphometry and function of the occipital cortex. By comparison, its impact on the perisylvian regions in the superior temporal plane (STP) is poorly understood, with many studies reporting null findings on this issue. Here we re-approach this question using a morphometric analysis that relied on fine-scale, manual annotation of 13 sub-regions within the STP and that quantified both univariate and multivariate differences in morphometry. We applied these analyses to both cortical thickness (CT) and surface area (SA) data from congenitally and late blind, as compared to two matched sighted control groups...
April 17, 2017: Brain and Language
https://www.readbyqxmd.com/read/28406648/mechanisms-of-change-in-cognitive-therapy-for-major-depressive-disorder-in-the-community-mental-health-setting
#4
Paul Crits-Christoph, Robert Gallop, Caroline K Diehl, Seohyun Yin, Mary Beth Connolly Gibbons
OBJECTIVE: This study examined the relation of change in theory-relevant cognitive variables to depressive symptom change over the course of cognitive therapy, as well as the specificity of change mechanisms to cognitive therapy as compared with dynamic therapy. METHOD: There were 237 adult outpatients who were randomized to either cognitive (n = 119) or dynamic (n = 118) therapy for major depressive disorder in a community mental health setting. Assessments of compensatory skills (Ways of Responding Community Version and Self-Report Version), dysfunctional attitudes (Dysfunctional Attitudes Scale), and depressogenic schemas (Psychological Distance Scaling Task) were obtained at baseline and months 1, 2, and 5 following baseline...
April 13, 2017: Journal of Consulting and Clinical Psychology
https://www.readbyqxmd.com/read/28388105/charge-transfer-excitations-from-particle-particle-random-phase-approximation-opportunities-and-challenges-arising-from-two-electron-deficient-systems
#5
Yang Yang, Adriel Dominguez, Du Zhang, Vitalij Lutsker, Thomas A Niehaus, Thomas Frauenheim, Weitao Yang
The particle-particle random phase approximation (pp-RPA) is a promising method for studying charge transfer(CT) excitations. Through a detailed analysis on two-electron deficient systems, we show that the pp-RPA is always able to recover the long-distance asymptotic -1/R trend for CT excitations as a result of the concerted effect between orbital energies and the pp-RPA kernel. We also provide quantitative results for systems with relatively short donor-acceptor distances. With conventional hybrid or range-separated functionals, the pp-RPA performs much better than time-dependent density functional theory (TDDFT), although it still gives underestimated results which are not as good as TDDFT with system-dependent tuned functionals...
March 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28321787/a-mathematical-theory-of-shape-and-neuro-fuzzy-methodology-based-diagnostic-analysis-a-comparative-study-on-early-detection-and-treatment-planning-of-brain-cancer
#6
Subrata Kar, D Dutta Majumder
BACKGROUND: Investigation of brain cancer can detect the abnormal growth of tissue in the brain using computed tomography (CT) scans and magnetic resonance (MR) images of patients. The proposed method classifies brain cancer on shape-based feature extraction as either benign or malignant. The authors used input variables such as shape distance (SD) and shape similarity measure (SSM) in fuzzy tools, and used fuzzy rules to evaluate the risk status as an output variable. We presented a classifier neural network system (NNS), namely Levenberg-Marquardt (LM), which is a feed-forward back-propagation learning algorithm used to train the NN for the status of brain cancer, if any, and which achieved satisfactory performance with 100% accuracy...
March 20, 2017: International Journal of Clinical Oncology
https://www.readbyqxmd.com/read/28294604/solvent-controlled-doublet-emission-of-an-organometallic-gold-i-complex-with-a-polychlorinated-diphenyl-4-pyridyl-methyl-radical-ligand-dual-fluorescence-and-enhanced-emission-efficiency
#7
Yasuyo Ogino, Tetsuro Kusamoto, Yohei Hattori, Masaki Shimada, Mizuho Tsuchiya, Yoshinori Yamanoi, Eiji Nishibori, Kunihisa Sugimoto, Hiroshi Nishihara
A paramagnetic, luminescent organometallic gold(I) complex Au(I)(C6F5)(PyBTM), where PyBTM is a photostable fluorescent polychlorinated diphenyl(4-pyridyl)methyl radical, was prepared, and its crystal and electronic structures and magnetic and optical properties were investigated. Magnetic studies using electron spin resonance spectroscopy and a superconducting quantum interference device magnetometer indicated the existence of S = (1)/2 spin per molecule, with the spin density distributed mainly on the PyBTM ligand...
April 3, 2017: Inorganic Chemistry
https://www.readbyqxmd.com/read/28282451/c-tactile-afferent-stimulating-touch-carries-a-positive-affective-value
#8
Ralph Pawling, Peter R Cannon, Francis P McGlone, Susannah C Walker
The rewarding sensation of touch in affiliative interactions is hypothesized to be underpinned by a specialized system of nerve fibers called C-Tactile afferents (CTs), which respond optimally to slowly moving, gentle touch, typical of a caress. However, empirical evidence to support the theory that CTs encode socially relevant, rewarding tactile information in humans is currently limited. While in healthy participants, touch applied at CT optimal velocities (1-10cm/sec) is reliably rated as subjectively pleasant, neuronopathy patients lacking large myelinated afferents, but with intact C-fibres, report that the conscious sensation elicited by stimulation of CTs is rather vague...
2017: PloS One
https://www.readbyqxmd.com/read/28225355/assessing-cardiac-function-from-total-variation-regularized-4d-c-arm-ct-in-the-presence-of-angular-undersampling
#9
O Taubmann, V Haase, G Lauritsch, Y Zheng, G Krings, J Hornegger, A Maier
Time-resolved tomographic cardiac imaging using an angiographic C-arm device may support clinicians during minimally invasive therapy by enabling a thorough analysis of the heart function directly in the catheter laboratory. However, clinically feasible acquisition protocols entail a highly challenging reconstruction problem which suffers from sparse angular sampling of the trajectory. Compressed sensing theory promises that useful images can be recovered despite massive undersampling by means of sparsity-based regularization...
April 7, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28216521/technique-and-theory-of-hollow-fiber-phantom-for-cerebral-ct-perfusion
#10
Eiji Okaniwa, Hiroyuki Hashimoto, Kazufumi Suzuki, Hiroshi Iimura, Shingo Suzaki, Kayoko Abe, Mituhiro Ejima, Shuji Sakai
We developed a phantom using a hollow-fiber hemodialyzer to evaluate the quantitative reliability of cerebral computed tomography (CT) perfusion. Our phantom consisted of a hollow-fiber hemodialyzer and a syringe-shaped X-ray device made up of resin. The phantom can give theoretical true values for cerebral blood volume, cerebral blood flow, and mean transit time. We compared the values measured in the phantom with predicted theoretical values. The purpose of the current report is to describe the theory and experimental technique used to obtain an absolute value in a phantom...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/28186469/blood-based-nucleic-acid-biomarkers-as-a-potential-tool-to-determine-radiation-therapy-response-in-non-small-cell-lung-cancer
#11
Christopher R Deig, Marc S Mendonca, Tim Lautenschlaeger
Lung cancer is the leading cause of cancer deaths worldwide, with smoking as the main risk factor. The use of low-dose computed tomography (LDCT) as a screening method has shown a 20% lung cancer specific mortality benefit; however, widespread implementation is estimated to add $1.3-$2.0 billion in annual national health care expenditures. Blood-based microRNAs (miRNAs), have been investigated in detail and found to be potentially useful biomarkers indicating the presence of lung cancer, especially when used as a companion test to LDCT...
February 10, 2017: Radiation Research
https://www.readbyqxmd.com/read/28149991/exciton-vibrational-resonance-and-dynamics-of-charge-separation-in-the-photosystem-ii-reaction-center
#12
Vladimir I Novoderezhkin, Elisabet Romero, Javier Prior, Rienk van Grondelle
The dynamics of charge separation in the photosystem II reaction center (PSII-RC) in the presence of intramolecular vibrations with their frequency matching the energy gap between the exciton state acting as the primary electron donor and the first charge-transfer (CT) state are investigated. A reduced PSII-RC 4-state model explicitly including a CT state is analyzed within Redfield relaxation theory in the multidimensional exciton-vibrational (vibronic) basis. This model is used to study coherent energy/electron transfers and their spectral signatures obtained by two-dimensional electronic spectroscopy (2DES)...
February 2, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28147535/simulating-the-absorption-spectra-of-helium-clusters-n%C3%A2-%C3%A2-70-150-231-300-using-a-charge-transfer-correction-to-superposition-of-fragment-single-excitations
#13
Qinghui Ge, Yuezhi Mao, Alec F White, Evgeny Epifanovsky, Kristina D Closser, Martin Head-Gordon
Simulations of the n = 2 absorption spectra of HeN (N = 70, 150, 231, 300) clusters are reported, with nuclear configurations sampled by path integral molecular dynamics. The electronic structure is treated by a new approach, ALMO-CIS+CT, which is a formulation of configuration interaction singles (CIS) based on absolutely localized molecular orbitals (ALMOs). The method generalizes the previously reported ALMO-CIS model [K. D. Closser et al. J. Chem. Theory Comput. 11, 5791 (2015)] to include spatially localized charge transfer (CT) effects...
January 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28129150/the-spurs-algorithm-for-resampling-an-irregularly-sampled-signal-onto-a-cartesian-grid
#14
Amir Kiperwas, Daniel Rosenfeld, Yonina C Eldar
We present an algorithm for resampling a function from its values on a non-Cartesian grid onto a Cartesian grid. This problem arises in many applications such as MRI, CT, radio astronomy and geophysics. Our algorithm, termed SParse Uniform ReSampling (SPURS), employs methods from modern sampling theory to achieve a small approximation error while maintaining low computational cost. The given non-Cartesian samples are projected onto a selected intermediate subspace, spanned by integer translations of a compactly supported kernel function...
November 1, 2016: IEEE Transactions on Medical Imaging
https://www.readbyqxmd.com/read/28117195/vomero-premaxillary-joint-a-marker-of-evolution-of-the-species
#15
S Botti, C Rumeau, P Gallet, R Jankowski
OBJECTIVE: According to evolutionary developmental (evo-devo) theory, the vomers are bones derived from the secondary palate. Growth of the palatine processes of the maxillae, including the precursors of vomer bones, results in midline fusion posteriorly to the primary palate, which forces the ascension of the vomer bones towards the primary nasal septum, formed by septal cartilage and the perpendicular plate of the ethmoid. According to this hypothesis, the anterior border of the vomer articulates with the posterior surface of the premaxilla in the incisive canal (IC)...
January 20, 2017: European Annals of Otorhinolaryngology, Head and Neck Diseases
https://www.readbyqxmd.com/read/28116309/analysis-of-the-osteogenic-effects-of-biomaterials-using-numerical-simulation
#16
Lan Wang, Jie Zhang, Wen Zhang, Hui-Lin Yang, Zong-Ping Luo
We describe the development of an optimization algorithm for determining the effects of different properties of implanted biomaterials on bone growth, based on the finite element method and bone self-optimization theory. The rate of osteogenesis and the bone density distribution of the implanted biomaterials were quantitatively analyzed. Using the proposed algorithm, a femur with implanted biodegradable biomaterials was simulated, and the osteogenic effects of different materials were measured. Simulation experiments mainly considered variations in the elastic modulus (20-3000 MPa) and degradation period (10, 20, and 30 days) for the implanted biodegradable biomaterials...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28109796/minimization-of-dental-implant-diameter-and-length-according-to-bone-quality-determined-by-finite-element-analysis-and-optimized-calculation
#17
Nana Ueda, Yoshiyuki Takayama, Atsuro Yokoyama
PURPOSE: The purpose of this study was to investigate the influences of bone quality and implant size on the maximum equivalent elastic strain (MES) in peri-implant bone using finite element (FE) analysis, and to minimize implant size via optimized calculation based on MES. METHODS: Three-dimensional FE models consisting of a mandible and a titanium implant with a superstructure were constructed and applied a vertical load or an oblique load of 60N. We investigated the effects of four variables: the thickness of the cortical bone (C), Young's modulus of the trabecular bone (T), and the diameter (D) and length (L) of the implant...
January 18, 2017: Journal of Prosthodontic Research
https://www.readbyqxmd.com/read/28106226/applied-taguchi-method-for-fatigue-testing-of-customized-hip-implant
#18
Mangesh R Dharme, Abhaykumar M Kuthe, Tushar R Deshmukh
PURPOSE: Human activities generate stresses, which vary with time and may result in fatigue failure of the customized hip implant. This study aims to investigate fatigue testing of customized hip implants using the minimum number of experiments by the Taguchi method, for 147 patients. This study was also useful to determine the influential geometrical parameters on the fatigue safety factor of customized hip implants. METHODS: Horizontal offset (HO), vertical offset (VO) and neck shaft angle (NSA) of the hip joint of 147 patients were measured on computed tomography (CT) scanned images...
February 10, 2017: International Journal of Artificial Organs
https://www.readbyqxmd.com/read/28093049/efficient-variational-approach-to-multimodal-registration-of%C3%A2-anatomical%C3%A2-and%C3%A2-functional-intra-patient-tumorous-brain-data
#19
Alvar-Ginés Legaz-Aparicio, Rafael Verdú-Monedero, Jorge Larrey-Ruiz, Juan Morales-Sánchez, Fernando López-Mir, Valery Naranjo, Ángela Bernabéu
This paper addresses the functional localization of intra-patient images of the brain. Functional images of the brain (fMRI and PET) provide information about brain function and metabolism whereas anatomical images (MRI and CT) supply the localization of structures with high spatial resolution. The goal is to find the geometric correspondence between functional and anatomical images in order to complement and fuse the information provided by each imaging modality. The proposed approach is based on a variational formulation of the image registration problem in the frequency domain...
November 29, 2016: International Journal of Neural Systems
https://www.readbyqxmd.com/read/28048018/su-f-j-52-a-novel-approach-to-x-ray-tube-quality-assurance-for-cbct-systems-in-order-to-better-assess-the-patient-imaging-dose-in-a-large-multi-unit-treatment-facility
#20
L Buckley, R Webb, C Lambert, B Nyiri, L Gerig
PURPOSE: To standardize the tube calibration for Elekta XVI cone beam CT (CBCT) systems in order to provide a meaningful estimate of the daily imaging dose and reduce the variation between units in a large centre with multiple treatment units. METHODS: Initial measurements of the output from the CBCT systems were made using a Farmer chamber and standard CTDI phantom. The correlation between the measured CTDI and the tube current was confirmed using an Unfors Xi detector which was then used to perform a tube current calibration on each unit...
June 2016: Medical Physics
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