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Journal articles on the topic 'Vogel spiral'

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Published: 7 July 2024
Last updated: 7 July 2024

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1

Razi, Mani, Ren Wang, Yanyan He, Robert M. Kirby, and Luca Dal Negro. "Optimization of Large-Scale Vogel Spiral Arrays of Plasmonic Nanoparticles." Plasmonics 14, no. 1 (July 7, 2018): 253–61. http://dx.doi.org/10.1007/s11468-018-0799-y.

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Gorsky, Sean, Ran Zhang, Abdullah Gok, Ren Wang, Kidanemariam Kebede, Alan Lenef, Madis Raukas, and Luca Dal Negro. "Directional light emission enhancement from LED-phosphor converters using dielectric Vogel spiral arrays." APL Photonics 3, no. 12 (December 2018): 126103. http://dx.doi.org/10.1063/1.5052637.

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3

Lawrence, Nate, Jacob Trevino, and Luca Dal Negro. "Control of optical orbital angular momentum by Vogel spiral arrays of metallic nanoparticles." Optics Letters 37, no. 24 (December 6, 2012): 5076. http://dx.doi.org/10.1364/ol.37.005076.

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4

Intonti, F., N. Caselli, N. Lawrence, J. Trevino, D. S. Wiersma, and L. Dal Negro. "Near-field distribution and propagation of scattering resonances in Vogel spiral arrays of dielectric nanopillars." New Journal of Physics 15, no. 8 (August 22, 2013): 085023. http://dx.doi.org/10.1088/1367-2630/15/8/085023.

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5

Trojak, Oliver J., Sean Gorsky, Connor Murray, Fabrizio Sgrignuoli, Felipe A. Pinheiro, Luca Dal Negro, and Luca Sapienza. "Cavity-enhanced light–matter interaction in Vogel-spiral devices as a platform for quantum photonics." Applied Physics Letters 118, no. 1 (January 4, 2021): 011103. http://dx.doi.org/10.1063/5.0034984.

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6

Wang, Nian-Mu, Huang Huang, and Chao Zhang. "Broadband second harmonic generation in aperiodic nonlinear photonic crystals: 1D projection from 2D Vogel sunflower spiral array." AIP Advances 11, no. 5 (May 1, 2021): 055219. http://dx.doi.org/10.1063/5.0052800.

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7

Manceñido, Miguel O., and Rémy Gourvennec. "A reappraisal of feeding current systems inferred for spire-bearing brachiopods." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 98, no. 3-4 (September 2007): 345–56. http://dx.doi.org/10.1017/s1755691007078462.

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ABSTRACTSpire-bearing brachiopods formally comprise four different rhynchonelliform orders. A calcified spiral brachidium (presumably supporting a spirolophe when alive) and variable median fold and sulcus (probably aiding separation of incurrent from excurrent flows) are peculiar characteristics they all share. Inferences regarding feeding current systems for these extinct taxa have long remained controversial. Two rival models (the Williams–Ager model and the Rudwick–Vogel model) have been developed, each of which has gained supporters as well as critics over the years. In this present paper they are both contrasted and reassessed on the basis of available evidence, together with a new approach that combines: (a) a morpho-functional analysis applying the plankton net as a suitable seston-collecting paradigm; (b) a review of actualistic data showing that all extant spirolophes are functionally inhalant (irrespective of water entering the valves laterally or not); (c) an evaluation of known outcomes from flume experiments yielding consistent empirical results where gaping shells are oriented transversally and dorsally upcurrent; and (d) a reappraisal of the distributions of certain epizoobionts and endosymbionts revealing compatible patterns. The evidence thus accumulated supports the main conclusion that, in most groups (with laterally tapering spiralia), the inhalant current was located medially with the exhalant currents on either side; only in atrypides (with centrally to dorsally tapering spiralia) does the reverse situation appear to have occurred.
8

Zhao, Taotao, Yanwen Hu, Shenhe Fu, Xiaonan Li, Yikun Liu, Hao Yin, Zhen Li, Juntao Li, and Zhenqiang Chen. "Aperiodic Vogel spirals for broadband optical wave focusing." Optics Letters 43, no. 24 (December 7, 2018): 5969. http://dx.doi.org/10.1364/ol.43.005969.

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9

Diebel, Falko, Patrick Rose, Martin Boguslawski, and Cornelia Denz. "Optical induction scheme for assembling nondiffracting aperiodic Vogel spirals." Applied Physics Letters 104, no. 19 (May 12, 2014): 191101. http://dx.doi.org/10.1063/1.4875237.

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10

Aubry, Geoffroy J., Luis A. Razo-López, Felipe A. Pinheiro, and Fabrice Mortessagne. "Experimental observation of electromagnetic wave localization in Vogel spirals." EPJ Web of Conferences 287 (2023): 04017. http://dx.doi.org/10.1051/epjconf/202328704017.

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We present experiments of microwave transport in planar Vogel spirals arrays of high permittivity dielectric constant. Despite the lack of disorder, wave transport in certain frequency regions is dominated by localized modes. We characterize these modes spatially, and find that in contrary to disorder induced Anderson localization, their radial decay does not only decay exponentially, but some modes are found to decay according to a power law or to a Gaussian profile. Nevertheless, by extracting experimentally the Thouless conductance, we find that the region where these Gaussian and power law modes exist are regions of low Thouless conductance, similarly to what is expected for Anderson localization. This study unveil the rich modal structure associated with these aperiodic point patterns, and pave the way toward a better understanding of wave localization in general.
11

Steckmann, Sven, Michael Knaup, and Marc Kachelrieß. "High performance cone-beam spiral backprojection with voxel-specific weighting." Physics in Medicine and Biology 54, no. 12 (May 28, 2009): 3691–708. http://dx.doi.org/10.1088/0031-9155/54/12/006.

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12

Trevino, Jacob, Seng Fatt Liew, Heeso Noh, Hui Cao, and Luca Dal Negro. "Geometrical structure, multifractal spectra and localized optical modes of aperiodic Vogel spirals." Optics Express 20, no. 3 (January 25, 2012): 3015. http://dx.doi.org/10.1364/oe.20.003015.

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13

Dal Negro, Luca, Nate Lawrence, and Jacob Trevino. "Analytical light scattering and orbital angular momentum spectra of arbitrary Vogel spirals." Optics Express 20, no. 16 (July 24, 2012): 18209. http://dx.doi.org/10.1364/oe.20.018209.

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14

Xu, Wenpeng, Qiuge Li, Hao Xu, Xiaoya Zhai, and Jingchao Jiang. "Voxel-based variable width continuous spiral path planning for 3D printing." Journal of Manufacturing Processes 107 (December 2023): 226–39. http://dx.doi.org/10.1016/j.jmapro.2023.10.044.

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15

Wang, Shuqiang, Yong Hu, Yanyan Shen, and Hanxiong Li. "Classification of Diffusion Tensor Metrics for the Diagnosis of a Myelopathic Cord Using Machine Learning." International Journal of Neural Systems 28, no. 02 (January 22, 2018): 1750036. http://dx.doi.org/10.1142/s0129065717500368.

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In this study, we propose an automated framework that combines diffusion tensor imaging (DTI) metrics with machine learning algorithms to accurately classify control groups and groups with cervical spondylotic myelopathy (CSM) in the spinal cord. The comparison between selected voxel-based classification and mean value-based classification were performed. A support vector machine (SVM) classifier using a selected voxel-based dataset produced an accuracy of 95.73%, sensitivity of 93.41% and specificity of 98.64%. The efficacy of each index of diffusion for classification was also evaluated. Using the proposed approach, myelopathic areas in CSM are detected to provide an accurate reference to assist spine surgeons in surgical planning in complicated cases.
16

Lerebours, Fleur, Kader Boulanouar, Michèle Barège, Marie Denuelle, Fabrice Bonneville, Pierre Payoux, Vincent Larrue, and Nelly Fabre. "Functional connectivity of hypothalamus in chronic migraine with medication overuse." Cephalalgia 39, no. 7 (March 5, 2019): 892–99. http://dx.doi.org/10.1177/0333102419833087.

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Objective To investigate the functional connectivity of the hypothalamus in chronic migraine compared to interictal episodic migraine in order to improve our understanding of migraine chronification. Methods Using task-free fMRI and ROI-to-ROI analysis, we compared anterior hypothalamus intrinsic connectivity with the spinal trigeminal nucleus in patients with chronic migraine (n = 25) to age- and sex-matched patients with episodic migraine in the interictal phase (n = 22). We also conducted a seed-to-voxel analysis with anterior hypothalamus as a seed. Results All patients with chronic migraine had medication overuse. We found a significant connectivity (T = 2.08, p = 0.024) between anterior hypothalamus and spinal trigeminal nucleus in the chronic group, whereas these two regions were not connected in the episodic group. The strength of connectivity was not correlated with pain intensity (rho: 0.09, p = 0.655). In the seed-to-voxel analysis, three regions were more connected with the anterior hypothalamus in the chronic group: The spinal trigeminal nuclei (MNI coordinate x = 2, y = −44, z = −62), the right dorsal anterior insula (MNI coordinate x = 10, y = 10, z = 18), and the right caudate (MNI coordinate x = 12, y = 28, z = 6). However, these correlations were no longer significant after whole brain FWE correction. Conclusion An increased functional connectivity between the anterior hypothalamus and the spinal trigeminal nucleus, as previously reported in preictal episodic migraine, was demonstrated in chronic migraine with medication overuse. This finding confirms a major role of the anterior hypothalamus in migraine and suggests that chronic migraineurs are locked in the preictal phase.
17

Ouellette, Russell, Constantina A. Treaba, Tobias Granberg, Elena Herranz, Valeria Barletta, Ambica Mehndiratta, Benjamin De Leener, et al. "7 T imaging reveals a gradient in spinal cord lesion distribution in multiple sclerosis." Brain 143, no. 10 (September 16, 2020): 2973–87. http://dx.doi.org/10.1093/brain/awaa249.

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Abstract We used 7 T MRI to: (i) characterize the grey and white matter pathology in the cervical spinal cord of patients with early relapsing-remitting and secondary progressive multiple sclerosis; (ii) assess the spinal cord lesion spatial distribution and the hypothesis of an outside-in pathological process possibly driven by CSF-mediated immune cytotoxic factors; and (iii) evaluate the association of spinal cord pathology with brain burden and its contribution to neurological disability. We prospectively recruited 20 relapsing-remitting, 15 secondary progressive multiple sclerosis participants and 11 age-matched healthy control subjects to undergo 7 T imaging of the cervical spinal cord and brain as well as conventional 3 T brain acquisition. Cervical spinal cord imaging at 7 T was used to segment grey and white matter, including lesions therein. Brain imaging at 7 T was used to segment cortical and white matter lesions and 3 T imaging for cortical thickness estimation. Cervical spinal cord lesions were mapped voxel-wise as a function of distance from the inner central canal CSF pool to the outer subpial surface. Similarly, brain white matter lesions were mapped voxel-wise as a function of distance from the ventricular system. Subjects with relapsing-remitting multiple sclerosis showed a greater predominance of spinal cord lesions nearer the outer subpial surface compared to secondary progressive cases. Inversely, secondary progressive participants presented with more centrally located lesions. Within the brain, there was a strong gradient of lesion formation nearest the ventricular system that was most evident in participants with secondary progressive multiple sclerosis. Lesion fractions within the spinal cord grey and white matter were related to the lesion fraction in cerebral white matter. Cortical thinning was the primary determinant of the Expanded Disability Status Scale, white matter lesion fractions in the spinal cord and brain of the 9-Hole Peg Test and cortical thickness and spinal cord grey matter cross-sectional area of the Timed 25-Foot Walk. Spinal cord lesions were localized nearest the subpial surfaces for those with relapsing-remitting and the central canal CSF surface in progressive disease, possibly implying CSF-mediated pathogenic mechanisms in lesion development that may differ between multiple sclerosis subtypes. These findings show that spinal cord lesions involve both grey and white matter from the early multiple sclerosis stages and occur mostly independent from brain pathology. Despite the prevalence of cervical spinal cord lesions and atrophy, brain pathology seems more strongly related to physical disability as measured by the Expanded Disability Status Scale.
18

Handa, Toshihiro, Miru Maebata, Takeru Murase, Shinji Fujita, Mikito Kohno, Nario Kuno, Mika Kuriki, et al. "Difference of the Gas Density Histograms in and out of spiral arms in Milky Way Galaxy." Proceedings of the International Astronomical Union 14, S345 (August 2018): 322–23. http://dx.doi.org/10.1017/s1743921319001649.

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Abstract“Gas Density Histogram (GDH)” is an observational counterpart of the probability density function (PDF) of the gas density of interstellar medium (ISM). We used 12CO data in (l, b) = (29°, 0) region from “FOREST unbiased galactic imaging survey with Nobeyama 45-m telescope (FUGIN)”, which is a large coverage survey in three CO (1-0) lines. Using the kinetic distance, we estimated the volume density of the voxel from the observed column density. The resultant GDHs of the inter-arm regions show lognormal or lognormal-like, but those in the spiral arm regions show flat-top shape.
19

Xu, Chenxi, Chen Zhang, Wei Zhao, Yining Liu, Ziyu Li, Zeyu Wang, Baole Lu, Kaige Wang, and Jintao Bai. "Fabrication of Micro/Nano Dual Needle Structures with Morphological Gradient Based on Two-Photon Polymerization Laser Direct Writing with Proactive Focus Compensation." Photonics 11, no. 2 (February 18, 2024): 187. http://dx.doi.org/10.3390/photonics11020187.

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Micro/nano structures with morphological gradients possess unique physical properties and significant applications in various research domains. This study proposes a straightforward and precise method for fabricating micro/nano structures with morphological gradients utilizing single-voxel synchronous control and a nano-piezoelectric translation stage in a two-photon laser direct writing technique. To address the defocusing issue in large-scale fabrication, a methodology for laser focus dynamic proactive compensation was developed based on fluorescence image analysis, which can achieve high-precision compensation of laser focus within the entire range of the nano-piezoelectric translation stage. Subsequently, the fabrication of micro/nano dual needle structures with morphological gradients were implemented by employing different writing speeds and voxel positions. The minimum height of the tip in the dual needle structure is 80 nm, with a linewidth of 171 nm, and a dual needle total length reaching 200 μm. Based on SEM (scanning electron microscope) and AFM (atomic force microscope) characterization, the dual needle structures fabricated by the method proposed in this study exhibit high symmetry and nanoscale gradient accuracy. Additionally, the fabrication of hexagonal lattice periodic structures assembled from morphological gradient needle structures and the size gradient Archimedean spiral structures validate the capability of the single voxel-based fabrication and proactive focus compensation method for complex gradient structure fabrication.
20

Merkel, M., T. Schemme, and C. Denz. "Aperiodic biomimetic Vogel spirals as diffractive optical elements for tailored light distribution in functional polymer layers." Journal of Optics 23, no. 6 (April 29, 2021): 065401. http://dx.doi.org/10.1088/2040-8986/abf8cc.

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21

Jin, Craig, Amelia Gully, Michael I. Proctor, Kirrie Ballard, Sheryl Foster, Tharinda Piyadasa, and Yaoyao Yue. "Exploring the relationship between real-time midsagittal images of the vocal tract and volumetric data." Journal of the Acoustical Society of America 154, no. 4_supplement (October 1, 2023): A244. http://dx.doi.org/10.1121/10.0023428.

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3D analysis of the vocal tract using dynamic MRI remains a technically difficult challenge. Various approaches have been explored such as using parametic models of the vocal tract (Yehia et al., 1997); integrating data across parallel slices of 2D dynamic data (Zhu et al., 2012); applying stack-of-spiral MRI sampling with 3D constrained reconstruction (Zhao et al., 2020); and combining static 3D and dynamic 2D data (Douros et al., 2019). In this work, we follow a similar approach to Douros et al. and explore the relationship between 2D real-time midsagittal images and 3D volumetric scans of the vocal tract. The real-time MRI midsagittal images are recorded during vowel-consonant-vowel vocal tasks, while the 3D volumetric scans are recorded during sustained vowels. We use large deformation diffeomorphic metric mapping as the foundation for this modeling work. We explore techniques to use constraints provided by the real-time MRI midsagittal images to enable smooth deformations of the 3D volumetric data. We focus on the feasibility of the methods and report on the types of constraints explored and the resulting deformations of the 3D volumetric data.
22

Jurkiewicz, M. T., A. P. Crawley, M. C. Verrier, M. G. Fehlings, and D. J. Mikulis. "Somatosensory cortical atrophy after spinal cord injury: A voxel-based morphometry study." Neurology 66, no. 5 (March 13, 2006): 762–64. http://dx.doi.org/10.1212/01.wnl.0000201276.28141.40.

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23

Pearl, Monica S., James X. Chen, Lydia Gregg, Diego San Millàn, Allan Belzberg, George Jallo, and Philippe Gailloud. "Angiographic Detection and Characterization of “Cryptic Venous Anomalies” Associated With Spinal Cord Cavernous Malformations Using Flat-Panel Catheter Angiotomography." Operative Neurosurgery 71, suppl_1 (May 16, 2012): ons125—ons132. http://dx.doi.org/10.1227/neu.0b013e31825d8f9a.

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BACKGROUND: Spinal cord cavernous malformations (CMs) are associated with 2 types of angiographically occult “cryptic venous anomalies,” which differ in location with respect to the spinal cord. The anatomic distinction between superficial and intramedullary is important in that the latter heighten the risks of CM resection. OBJECTIVE: To report the observations of both types of cryptic venous anomalies documented during spinal digital subtraction angiography enhanced with flat-panel catheter angiotomography (FPCA). METHODS: Spinal digital subtraction angiography enhanced with FPCA was performed in 2 adult patients with magnetic resonance imaging--documented intramedullary spinal cord CMs and prominent, nonspecific flow voids at the same levels. FPCA was obtained by selective injection of left T4 (case 1) and left T9 (case 2) with 5F Cobra 2 catheters (Terumo, Japan) during a 20-second rotational acquisition. Thirty milliliters of a 75% saline and 25% contrast solution (Omnipaque 300; GE) was administered. The rotational data set was reconstructed on a dedicated workstation (Leonardo; Siemens, Erlangen, Germany) through the use of regular and high-resolution matrixes, 0.4- and 0.1-mm voxel size, respectively. RESULTS: Spinal digital subtraction angiography was unremarkable in both cases. In case 1, FPCA findings indicated an atypical network of prominent posterior perimedullary veins. In case 2, FPCA identified radially oriented channels forming a caput medusae pattern collecting into an enlarged intramedullary vein. CONCLUSION: The unique ability of FPCA to image the spinal venous system enables the angiographic detection and characterization of abnormal spinal veins associated with CMs. Differentiating between the types of associated cryptic venous malformations may aid in surgical planning because the intramedullary type is associated with a higher risk of surgical complication.
24

Bezshapochny, Sergey B., Oleh G. Avrunin, Andrey V. Loburets, Valery V. Loburets, and Yuri A. Gasyuk. "Forecasting of functional results of septoplasty." OTORHINOLARYNGOLOGY, no. 4(3) 2020 (September 25, 2020): 67–72. http://dx.doi.org/10.37219/2528-8253-2020-4-67.

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Objective: to define the effectiveness of forecasting of the functional result of septoplasty. Materials and methods: forecasting based on endorhinoscopy data, spiral computed tomography, formation of a spatial segmented lofting model of nasal cavity, construction of an aerodynamic model based on a unified generalized voxel tomography of the upper respiratory tract and rhinomanometry, which were conducted in 28 patients. Results: it was found that the correction of various variants of the deviation of nasal septum in more than 80% of cases significantly reduces the aerodynamic nasal resistance. Forecasting at septoplasty allows to quantify functional results, which do not always coincide with the real ones. The introduction of more highly accurate innovative diagnostic methods in the future will improve the efficiency of forecasting in rhinosurgery
25

Staartjes, Victor E., Peter R. Seevinck, W. Peter Vandertop, Marijn van Stralen, and Marc L. Schröder. "Magnetic resonance imaging–based synthetic computed tomography of the lumbar spine for surgical planning: a clinical proof-of-concept." Neurosurgical Focus 50, no. 1 (January 2021): E13. http://dx.doi.org/10.3171/2020.10.focus20801.

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OBJECTIVEComputed tomography scanning of the lumbar spine incurs a radiation dose ranging from 3.5 mSv to 19.5 mSv as well as relevant costs and is commonly necessary for spinal neuronavigation. Mitigation of the need for treatment-planning CT scans in the presence of MRI facilitated by MRI-based synthetic CT (sCT) would revolutionize navigated lumbar spine surgery. The authors aim to demonstrate, as a proof of concept, the capability of deep learning–based generation of sCT scans from MRI of the lumbar spine in 3 cases and to evaluate the potential of sCT for surgical planning.METHODSSynthetic CT reconstructions were made using a prototype version of the “BoneMRI” software. This deep learning–based image synthesis method relies on a convolutional neural network trained on paired MRI-CT data. A specific but generally available 4-minute 3D radiofrequency-spoiled T1-weighted multiple gradient echo MRI sequence was supplemented to a 1.5T lumbar spine MRI acquisition protocol.RESULTSIn the 3 presented cases, the prototype sCT method allowed voxel-wise radiodensity estimation from MRI, resulting in qualitatively adequate CT images of the lumbar spine based on visual inspection. Normal as well as pathological structures were reliably visualized. In the first case, in which a spiral CT scan was available as a control, a volume CT dose index (CTDIvol) of 12.9 mGy could thus have been avoided. Pedicle screw trajectories and screw thickness were estimable based on sCT findings.CONCLUSIONSThe evaluated prototype BoneMRI method enables generation of sCT scans from MRI images with only minor changes in the acquisition protocol, with a potential to reduce workflow complexity, radiation exposure, and costs. The quality of the generated CT scans was adequate based on visual inspection and could potentially be used for surgical planning, intraoperative neuronavigation, or for diagnostic purposes in an adjunctive manner.
26

Toosy, A. T., N. Kou, D. Altmann, C. A. M. Wheeler-Kingshott, A. J. Thompson, and O. Ciccarelli. "Voxel-based cervical spinal cord mapping of diffusion abnormalities in MS-related myelitis." Neurology 83, no. 15 (September 3, 2014): 1321–25. http://dx.doi.org/10.1212/wnl.0000000000000857.

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27

Milella, Giammarco, Diletta Sciancalepore, Giada Cavallaro, Glauco Piccirilli, Alfredo Gabriele Nanni, Angela Fraddosio, Eustachio D’Errico, Damiano Paolicelli, Maria Luisa Fiorella, and Isabella Laura Simone. "Acoustic Voice Analysis as a Useful Tool to Discriminate Different ALS Phenotypes." Biomedicines 11, no. 9 (August 31, 2023): 2439. http://dx.doi.org/10.3390/biomedicines11092439.

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Approximately 80–96% of people with amyotrophic lateral sclerosis (ALS) become unable to speak during the disease progression. Assessing upper and lower motor neuron impairment in bulbar regions of ALS patients remains challenging, particularly in distinguishing spastic and flaccid dysarthria. This study aimed to evaluate acoustic voice parameters as useful biomarkers to discriminate ALS clinical phenotypes. Triangular vowel space area (tVSA), alternating motion rates (AMRs), and sequential motion rates (SMRs) were analyzed in 36 ALS patients and 20 sex/age-matched healthy controls (HCs). tVSA, AMR, and SMR values significantly differed between ALS and HCs, and between ALS with prevalent upper (pUMN) and lower motor neuron (pLMN) impairment. tVSA showed higher accuracy in discriminating pUMN from pLMN patients. AMR and SMR were significantly lower in patients with bulbar onset than those with spinal onset, both with and without bulbar symptoms. Furthermore, these values were also lower in patients with spinal onset associated with bulbar symptoms than in those with spinal onset alone. Additionally, AMR and SMR values correlated with the degree of dysphagia. Acoustic voice analysis may be considered a useful prognostic tool to differentiate spastic and flaccid dysarthria and to assess the degree of bulbar involvement in ALS.
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Chuelov, S. B., and A. L. Rossina. "Alveolar and neotropical echinococcosis." CHILDREN INFECTIONS 21, no. 4 (November 24, 2022): 57–61. http://dx.doi.org/10.22627/2072-8107-2022-21-4-57-61.

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The urgency of the problem of human alveolar and neotropic echinococcosis is due to polymorphism and the severity of clinical manifestations. The purpose and result of the work is to summarize the data available in the literature on the etiology, epidemiology, clinic, diagnosis, treatment, prevention of alveolar and neotropic echinococcosis in humans. Conclusion. The causative agent of human alveolar echinococcosis is E. multilocularis, neotropic – E. vogeli, E. oligarthra. The liver and lungs are most often affected, less often other organs of the abdominal cavity, bones, brain, spinal cord, eyes, etc. Diagnostics is carried out on the basis of a complex of clinical, instrumental, serological, molecular genetic studies. Treatment includes surgical removal of parasitic cysts and drug therapy.
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Jia, ZheShu, DeYun Chen, and Bo Wang. "Research on Improved Ray Casting Algorithm and Its Application in Three-Dimensional Reconstruction." Shock and Vibration 2021 (August 5, 2021): 1–6. http://dx.doi.org/10.1155/2021/8718523.

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Spinal pathology treatment has become an urgent issue to be solved. How to effectively prevent and treat spinal pathology has become a research hotspot in the field of surgery. Aiming at the problem of too long volume rendering time caused by the trilinear interpolation sampling method in the reconstruction and visualization of the vertebra 3D model, an improved ray projection algorithm is proposed to quickly reconstruct a 3D vertebra model from medical CT vertebra images. This method first classifies CT data, assigns corresponding color values and opacity transfer functions to different types of data, and then uses inverse distance-weighted interpolation (IDWI) sampling to replace the trilinear interpolation sampling method for the voxel where the sampling point is located to accelerate the interpolation operation. The color value and opacity of the sampling points are obtained, and finally, the attributes of all the sampling points are synthesized and calculated to obtain the final rendering effect, and the reconstruction of the three-dimensional vertebra model is completed. Experimental results show that the proposed method not only can obtain higher quality rendered images but also has a certain improvement in rendering speed compared with traditional algorithms.
30

Azzarito, Michela, Sreenath P. Kyathanahally, Yaël Balbastre, Maryam Seif, Claudia Blaiotta, Martina F. Callaghan, John Ashburner, and Patrick Freund. "Simultaneous voxel‐wise analysis of brain and spinal cord morphometry and microstructure within the SPM framework." Human Brain Mapping 42, no. 1 (September 29, 2020): 220–32. http://dx.doi.org/10.1002/hbm.25218.

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31

Sillery, Emma, Richard G. Bittar, Matthew D. Robson, Timothy E. J. Behrens, John Stein, Tipu Z. Aziz, and Heidi Johansen-Berg. "Connectivity of the human periventricular—periaqueductal gray region." Journal of Neurosurgery 103, no. 6 (December 2005): 1030–34. http://dx.doi.org/10.3171/jns.2005.103.6.1030.

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Object. The periventricular gray (PVG) zone and its continuation, the periaqueductal gray (PAG) substance, have been targets for deep brain stimulation (DBS) in the alleviation of intractable pain for longer than two decades. Nevertheless, the anatomical connectivity of this region has been fairly poorly defined. The effects of DBS in this region are probably related to the release of endogenous endorphins, but until the connectivity of this region is better understood the mechanisms will remain unclear. Methods. Diffusion tractography was used to trace the pathways of the PVG—PAG region in seven healthy human volunteers. Images were acquired with the aid of a 1.5-tesla magnetic resonance imaging system. The region of interest was located just lateral to the posterior commissure and extended caudally to the level of the superior colliculus. Probabilistic diffusion tractography was performed from each voxel in each patient's PVG—PAG region. The PVG—PAG region was found to yield descending projections to the spinal cord and cerebellum. Ascending projections to the thalamus and frontal lobes were also observed. Conclusions. These findings suggest that the PVG—PAG region may modulate pain by two mechanisms: one involving the antinociceptive system in the spinal cord and the other involving influences on the central pain network.
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Meyer, Cassandra E., Josephine L. Gao, James Ying-Jie Cheng, Mandavi R. Oberoi, Hadley Johnsonbaugh, Stefano Lepore, Florian Kurth, et al. "Axonal damage in spinal cord is associated with gray matter atrophy in sensorimotor cortex in experimental autoimmune encephalomyelitis." Multiple Sclerosis Journal 26, no. 3 (March 7, 2019): 294–303. http://dx.doi.org/10.1177/1352458519830614.

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Background: Gray matter (GM) atrophy in brain is one of the best predictors of long-term disability in multiple sclerosis (MS), and recent findings have revealed that localized GM atrophy is associated with clinical disabilities. GM atrophy associated with each disability mapped to a distinct brain region, revealing a disability-specific atlas (DSA) of GM loss. Objective: To uncover the mechanisms underlying the development of localized GM atrophy. Methods: We used voxel-based morphometry (VBM) to evaluate localized GM atrophy and Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging-compatible Tissue-hYdrogel (CLARITY) to evaluate specific pathologies in mice with experimental autoimmune encephalomyelitis (EAE). Results: We observed extensive GM atrophy throughout the cerebral cortex, with additional foci in the thalamus and caudoputamen, in mice with EAE compared to normal controls. Next, we generated pathology-specific atlases (PSAs), voxelwise mappings of the correlation between specific pathologies and localized GM atrophy. Interestingly, axonal damage (end-bulbs and ovoids) in the spinal cord strongly correlated with GM atrophy in the sensorimotor cortex of the brain. Conclusion: The combination of VBM with CLARITY in EAE can localize GM atrophy in brain that is associated with a specific pathology in spinal cord, revealing a PSA of GM loss.
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Kerbrat, Anne, Charley Gros, Atef Badji, Elise Bannier, Francesca Galassi, Benoit Combès, Raphaël Chouteau, et al. "Multiple sclerosis lesions in motor tracts from brain to cervical cord: spatial distribution and correlation with disability." Brain 143, no. 7 (June 23, 2020): 2089–105. http://dx.doi.org/10.1093/brain/awaa162.

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Abstract Despite important efforts to solve the clinico-radiological paradox, correlation between lesion load and physical disability in patients with multiple sclerosis remains modest. One hypothesis could be that lesion location in corticospinal tracts plays a key role in explaining motor impairment. In this study, we describe the distribution of lesions along the corticospinal tracts from the cortex to the cervical spinal cord in patients with various disease phenotypes and disability status. We also assess the link between lesion load and location within corticospinal tracts, and disability at baseline and 2-year follow-up. We retrospectively included 290 patients (22 clinically isolated syndrome, 198 relapsing remitting, 39 secondary progressive, 31 primary progressive multiple sclerosis) from eight sites. Lesions were segmented on both brain (T2-FLAIR or T2-weighted) and cervical (axial T2- or T2*-weighted) MRI scans. Data were processed using an automated and publicly available pipeline. Brain, brainstem and spinal cord portions of the corticospinal tracts were identified using probabilistic atlases to measure the lesion volume fraction. Lesion frequency maps were produced for each phenotype and disability scores assessed with Expanded Disability Status Scale score and pyramidal functional system score. Results show that lesions were not homogeneously distributed along the corticospinal tracts, with the highest lesion frequency in the corona radiata and between C2 and C4 vertebral levels. The lesion volume fraction in the corticospinal tracts was higher in secondary and primary progressive patients (mean = 3.6 ± 2.7% and 2.9 ± 2.4%), compared to relapsing-remitting patients (1.6 ± 2.1%, both P < 0.0001). Voxel-wise analyses confirmed that lesion frequency was higher in progressive compared to relapsing-remitting patients, with significant bilateral clusters in the spinal cord corticospinal tracts (P < 0.01). The baseline Expanded Disability Status Scale score was associated with lesion volume fraction within the brain (r = 0.31, P < 0.0001), brainstem (r = 0.45, P < 0.0001) and spinal cord (r = 0.57, P < 0.0001) corticospinal tracts. The spinal cord corticospinal tracts lesion volume fraction remained the strongest factor in the multiple linear regression model, independently from cord atrophy. Baseline spinal cord corticospinal tracts lesion volume fraction was also associated with disability progression at 2-year follow-up (P = 0.003). Our results suggest a cumulative effect of lesions within the corticospinal tracts along the brain, brainstem and spinal cord portions to explain physical disability in multiple sclerosis patients, with a predominant impact of intramedullary lesions.
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Faranna, V. "Angio-TC: Stato dell'arte e sviluppi futuri." Rivista di Neuroradiologia 10, no. 2_suppl (October 1997): 79–81. http://dx.doi.org/10.1177/19714009970100s231.

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The development of spiral acquisition techniques and the growing technology applied to both CT equipment and post-processing systems, have shown CT angiography (CTA), to be a complementary method to conventional Angiography, magnetic resonance angiography (MRA) or ultrasound, for the morphologic evaluation of vascular structures. Through the administration via intravenous injection of a contrast media and by means of a fast acquisition of the Region Of Interest, we obtain the primary information to be processed and displayed according to various imaging techniques: Axial images, Multiplanar Reformatting (MPR), volume rendering (3D) or shaded surface display (SSD), Maximum Intensity Projection (MIP), Endoscopic-CT etc. All of these processing methods, perform as a first step of the whole process, longitudinal interpolations by the data of the images. Even though few methods to improve the quality of the images exist, among these the use of overlapping sections, the precision requires of the post-processing procedures to accomplish the medical requirements for diagnosis, is affected by a common factor which is the absolute anisotropicity of the acquisition voxel (dimension along the “Z” axis different and bigger than those in the transverse plane). This represents the goal-parameter on which the various competitors will have to focus their efforts in order to obtain results with an improved diagnostic validity. At present, the systems with dual-slice acquisition, represent the first step of what will be the acquisition technology of the future: “multi-slice”. At the same time, the technologic growth of postprocessing workstations, will permit the development of new clinical applications combined with Spiral-CT acquisition which will broaden the horizons of modern medicine.
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Dumarey, Nicolas E., Nicolas Massager, Steven Laureys, and Serge Goldman. "Voxel-based assessment of spinal tap test-induced regional cerebral blood flow changes in normal pressure hydrocephalus." Nuclear Medicine Communications 26, no. 9 (September 2005): 757–63. http://dx.doi.org/10.1097/01.mnm.0000170937.90958.22.

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De Groote, Sander, Lisa Goudman, Peter Van Schuerbeek, Ronald Peeters, Stefan Sunaert, Bengt Linderoth, Jose De Andrés, Philippe Rigoard, Mats De Jaeger, and Maarten Moens. "Effects of spinal cord stimulation on voxel-based brain morphometry in patients with failed back surgery syndrome." Clinical Neurophysiology 131, no. 11 (November 2020): 2578–87. http://dx.doi.org/10.1016/j.clinph.2020.07.024.

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Si-hoe, K. M., S. H. Teoh, and Jeremy Teo. "Radio-Translucent 3-Axis Mechanical Testing Rig for the Spine in Micro-CT." Journal of Biomechanical Engineering 128, no. 6 (June 14, 2006): 957–64. http://dx.doi.org/10.1115/1.2375136.

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To date, no apparatus has yet been devised which would allow the study of bone microstructure of the whole vertebrae under mechanical loading. This paper outlines the design and development of a 3-axis radio-translucent mechanical testing rig for spinal research and testing. This rig is to be used in conjunction with a Shimadzu micro-CT scanner. Several tests were conducted to verify the feasibility of the rig design. First, the maximum range of deformation in compression, flexion\extension, and lateral bending that could be exerted on a goat lumbar functional spinal unit was evaluated using the noncontact digital markers method. Stepwise compression loading was also conducted on a single porcine vertebra and the loading data was compared to results obtained from an industrial grade compression testing machine. Finally, micro-CT scans of a porcine vertebra prior to and at a compression failure strain were obtained. The rig was confirmed to be able to exert pure moment loading in the above mentioned modes of deformation and the extent of deformation was comparable to previous documented results. The stepwise compression loading conducted in the rig was also found to effectively approximate a continuous loading of the same specimen in an industrial grade compression testing machine. Finally, resultant micro-CT images of isotropic resolution 32.80μm of a porcine vertebra loaded in the rig were obtained. For the first time, trabecular microarchitecture detail of a whole vertebra buckling under 12.1% failure compression strain loading was studied using voxel-data visualization software. These initial series of tests verify the feasibility of the rig as an apparatus incorporating spinal testing and imaging.
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Yazbek, Sandrine, Sanjay P. Prabhu, Pauline Connaughton, Patricia E. Grant, and Borjan Gagoski. "Comparison of accelerated 3-D spiral chemical shift imaging and single-voxel spectroscopy at 3T in the pediatric age group." Pediatric Radiology 45, no. 9 (April 1, 2015): 1417–22. http://dx.doi.org/10.1007/s00247-015-3311-2.

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Huber, Eveline, Gergely David, Alan J. Thompson, Nikolaus Weiskopf, Siawoosh Mohammadi, and Patrick Freund. "Dorsal and ventral horn atrophy is associated with clinical outcome after spinal cord injury." Neurology 90, no. 17 (March 28, 2018): e1510-e1522. http://dx.doi.org/10.1212/wnl.0000000000005361.

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ObjectiveTo investigate whether gray matter pathology above the level of injury, alongside white matter changes, also contributes to sensorimotor impairments after spinal cord injury.MethodsA 3T MRI protocol was acquired in 17 tetraplegic patients and 21 controls. A sagittal T2-weighted sequence was used to characterize lesion severity. At the C2-3 level, a high-resolution T2*-weighted sequence was used to assess cross-sectional areas of gray and white matter, including their subcompartments; a diffusion-weighted sequence was used to compute voxel-based diffusion indices. Regression models determined associations between lesion severity and tissue-specific neurodegeneration and associations between the latter with neurophysiologic and clinical outcome.ResultsNeurodegeneration was evident within the dorsal and ventral horns and white matter above the level of injury. Tract-specific neurodegeneration was associated with prolonged conduction of appropriate electrophysiologic recordings. Dorsal horn atrophy was associated with sensory outcome, while ventral horn atrophy was associated with motor outcome. White matter integrity of dorsal columns and corticospinal tracts was associated with daily-life independence.ConclusionOur results suggest that, next to anterograde and retrograde degeneration of white matter tracts, neuronal circuits within the spinal cord far above the level of injury undergo transsynaptic neurodegeneration, resulting in specific gray matter changes. Such improved understanding of tissue-specific cord pathology offers potential biomarkers with more efficient targeting and monitoring of neuroregenerative (i.e., white matter) and neuroprotective (i.e., gray matter) agents.
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Chen, Xin, Ling Wang, Weimin Zheng, Yanhui Yang, Beining Yang, Yongsheng Hu, Jubao Du, Xuejing Li, Jie Lu, and Nan Chen. "The gray matter atrophy and related network changes occur in the higher cognitive region rather than the primary sensorimotor cortex after spinal cord injury." PeerJ 11 (October 9, 2023): e16172. http://dx.doi.org/10.7717/peerj.16172.

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Objective This study used functional magnetic resonance imaging (fMRI) to explore brain structural and related network changes in patients with spinal cord injury (SCI). Methods Thirty-one right-handed SCI patients and 31 gender- and age-matched healthy controls (HC) were included. The gray matter volume (GMV) changes in SCI patients were observed using voxel-based morphometry (VBM). Then, these altered gray matter clusters were used as the regions of interest (ROIs) for whole-brain functional connectivity (FC) analysis to detect related functional changes. The potential association between GMV and FC values with the visual analog scale (VAS), the American Spinal Injury Association (ASIA) score, and the course of injuries was investigated through partial correlation analysis. Results GMV of the frontal, temporal, and insular cortices was lower in the SCI group than in the HC group. No GMV changes were found in the primary sensorimotor area in the SCI group. Besides, the altered FC regions were not in the primary sensorimotor area but in the cingulate gyrus, supplementary motor area, precuneus, frontal lobe, and insular. Additionally, some of these altered GMV and FC regions were correlated with ASIA motor scores, indicating that higher cognitive regions can affect motor function in SCI patients. Conclusions This study demonstrated that gray matter and related network reorganization in patients with SCI occurred in higher cognitive regions. Future rehabilitation strategies should focus more on cognitive functions.
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Karimian, Reza, Mansoor Dashti Ardakani, Shahrokh Ahmadi, and Mona Zaghloul. "Human Body Specific Absorption Rate Reduction Employing a Compact Magneto-Dielectric AMC Structure for 5G Massive-MIMO Applications." Eng 2, no. 4 (November 4, 2021): 501–11. http://dx.doi.org/10.3390/eng2040032.

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A compact artificial magnetic conductor (AMC) structure for the application of specific absorption rate (SAR) reduction is presented in this paper. A magneto-dielectric (MD) structure as a host of AMC substrate is used to miniaturize the AMC size. The magneto-dielectric has been designed with a low-profile spiral loop in a way to have a high permittivity and permeability for the desired center frequency of 3.5 GHz. Simulation results confirm the zero-degree reflection phase of the proposed AMC unit cell. Moreover, a 70% reduction has been achieved in comparison to the conventional AMC. To validate the simulation results, a prototype of the board is fabricated and measured with a coplanar waveguide (CPW) antenna for the reflection coefficient. The measurement results display an excellent agreement with the simulation ones. A VOXEL model of a human body is utilized to determine the SAR value of the proposed structure. Considering the maximum SAR value for an average of 10 g human tissue, more than 70% SAR reduction is verified for the CPW antenna with the recommended MD-AMC structure compared to a conventional single CPW antenna.
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Ketten, Darlene R., Andrea M. Simmons, and James A. Simmons. "Bats to belugas: Functional anatomy of air versus water biosonar." Journal of the Acoustical Society of America 153, no. 3_supplement (March 1, 2023): A94. http://dx.doi.org/10.1121/10.0018280.

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Acoustic task similarities of odontocetes (toothed whales) and microchiropterans (insectivorous bats) suggest they have common biosonar mechanisms. However, media differences; e.g., sound speeds in air versus water, may have driven variations in auditory system adaptations. We examined the peripheral auditory system of an FM bat (big brown bat Eptesicus fuscus) and two toothed whale species (harbor porpoise Phocoena phocoena; bottlenose dolphin Tursiops truncatu) using ultra high resolution (11 μm) isotropic voxel microCT. Significant differences were found among species for oval window location, cochlear length, basilar membrane gradients, cochlear spiral morphometry, cochlear curvature, and basilar membrane stiffness. High and low frequency hearing range cut-offs correlate with basilar membrane thickness/width ratios and cochlear radii of curvature. These features predict species specific high and low frequency hearing limits. Harbor porpoises, the highest frequency echolocator in the study, have large basal basilar membrane ratios and a “foveal” region with a constant membrane ratio similar to those reported for some bat species, consistent with a “stretched” frequency region. Furthermore, both the bats and harbor porpoises examined displayed unusual stapedial input locations and tightly coiled cochleae, specializations that may enhance ultrasonic frequency signal resolution and diminish low frequency cochlear propagation.
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Freund, Patrick A. B., Catherine Dalton, Claudia A. M. Wheeler-Kingshott, Janice Glensman, David Bradbury, Alan J. Thompson, and Nikolaus Weiskopf. "Method for simultaneous voxel-based morphometry of the brain and cervical spinal cord area measurements using 3D-MDEFT." Journal of Magnetic Resonance Imaging 32, no. 5 (October 28, 2010): 1242–47. http://dx.doi.org/10.1002/jmri.22340.

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Komlosi, Peter, Deborah Grady, Justin S. Smith, Christopher I. Shaffrey, Allen R. Goode, Patricia G. Judy, Mark Shaffrey, and Max Wintermark. "Evaluation of monoenergetic imaging to reduce metallic instrumentation artifacts in computed tomography of the cervical spine." Journal of Neurosurgery: Spine 22, no. 1 (January 2015): 34–38. http://dx.doi.org/10.3171/2014.10.spine14463.

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OBJECT Monoenergetic imaging with dual-energy CT has been proposed to reduce metallic artifacts in comparison with conventional polychromatic CT. The purpose of this study is to systematically evaluate and define the optimal dual-energy CT imaging parameters for specific cervical spinal implant alloy compositions. METHODS Spinal fixation rods of cobalt-chromium or titanium alloy inserted into the cervical spine section of an Alderson Rando anthropomorphic phantom were imaged ex vivo with fast-kilovoltage switching CT at 80 and 140 peak kV. The collimation width and field of view were varied between 20 and 40 mm and medium to large, respectively. Extrapolated monoenergetic images were generated at 70, 90, 110, and 130 kiloelectron volts (keV). The standard deviation of voxel intensities along a circular line profile around the spine was used as an index of the magnitude of metallic artifact. RESULTS The metallic artifact was more conspicuous around the fixation rods made of cobalt-chromium than those of titanium alloy. The magnitude of metallic artifact seen with titanium fixation rods was minimized at monoenergies of 90 keV and higher, using a collimation width of 20 mm and large field of view. The magnitude of metallic artifact with cobalt-chromium fixation rods was minimized at monoenergies of 110 keV and higher; collimation width or field of view had no effect. CONCLUSIONS Optimization of acquisition settings used with monoenergetic CT studies might yield reduced metallic artifacts.
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Shoraka, Omid, Shreya Mandloi, Mashaal Syed, Sara Talheimer, Hsiangkuo Yuan, James J. Evans, Joshua E. Heller, et al. "126 Association of PAG Connectivity in SCI Subjects With Neuropathic Pain in a Resting-State FMRI Study." Neurosurgery 70, Supplement_1 (April 2024): 26. http://dx.doi.org/10.1227/neu.0000000000002809_126.

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INTRODUCTION: Neuropathic pain (NP) is estimated to be present in 61% of subjects with chronic spinal cord injury (SCI). Periaqueductal Grey (PAG) plays a crucial role in descending pain modulation system. Few studies assessed PAG’s functional connectivity (FC) in pain syndromes, however, it has not been studied in SCI. METHODS: 10 SCI subjects with NP were divided into two groups (moderate-severe n = 7, mild-no pain n = 3), and 10 healthy controls (HC) were enrolled. Resting-state fMRI was performed for subjects using a 3T Philips Ingenia scanner with a dedicated 32 channels head coil. Seed-to-voxel analysis was performed using CONN toolbox with the PAG as the seed region. Group-based analysis was performed between three groups with age and gender as confounding variables. A voxel threshold p-value of <0.05 was used, with the results corrected for multiple comparisons using fdr with a significance level of 0.05. RESULTS: Compared to HCs, SCI with NP demonstrated decreased FC between PAG and one cluster. SCI with pain compared to SCI without pain demonstrated Increased FC in one and decreased FC in two clusters. For each common anatomical region between pairwise analyses, FC alterations were compared to assess whether they are the result of SCI or NP. CONCLUSIONS: Altered FC was observed between PAG and regions involved in the pain modulation in SCI with NP compared with SCI without pain and HCs. We hypothesized that alterations between PAG and the Frontal cortex, Thalamus, Brain stem, and Cerebellum could be the result of NP sequela rather than the SCI itself. Further studies with more subjects will be needed to assess this hypothesis.
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Rigby, A. J., T. J. T. Moore, D. J. Eden, J. S. Urquhart, S. E. Ragan, N. Peretto, R. Plume, M. A. Thompson, M. J. Currie, and G. Park. "CHIMPS: physical properties of molecular clumps across the inner Galaxy." Astronomy & Astrophysics 632 (November 27, 2019): A58. http://dx.doi.org/10.1051/0004-6361/201935236.

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The latest generation of high-angular-resolution unbiased Galactic plane surveys in molecular-gas tracers are enabling the interiors of molecular clouds to be studied across a range of environments. The CO Heterodyne Inner Milky Way Plane Survey (CHIMPS) simultaneously mapped a sector of the inner Galactic plane, within 27.8° ≲ ℓ ≲ 46.2° and |b|≤ 0°.5, in 13CO (3–2) and C18O (3–2) at an angular resolution of 15 arcsec. The combination of the CHIMPS data with 12CO (3–2) data from the CO High Resolution Survey (COHRS) has enabled us to perform a voxel-by-voxel local-thermodynamic-equilibrium (LTE) analysis, determining the excitation temperature, optical depth, and column density of 13CO at each ℓ, b, v position. Distances to discrete sources identified by FELLWALKER in the 13CO (3–2) emission maps were determined, allowing the calculation of numerous physical properties of the sources, and we present the first source catalogues in this paper. We find that, in terms of size and density, the CHIMPS sources represent an intermediate population between large-scale molecular clouds identified by CO and dense clumps seen in thermal dust continuum emission, and therefore represent the bulk transition from the diffuse to the dense phase of molecular gas. We do not find any significant systematic variations in the masses, column densities, virial parameters, mean excitation temperature, or the turbulent pressure over the range of Galactocentric distance probed, but we do find a shallow increase in the mean volume density with increasing Galactocentric distance. We find that inter-arm clumps have significantly narrower linewidths, and lower virial parameters and excitation temperatures than clumps located in spiral arms. When considering the most reliable distance-limited subsamples, the largest variations occur on the clump-to-clump scale, echoing similar recent studies that suggest that the star-forming process is largely insensitive to the Galactic-scale environment, at least within the inner disc.
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Scholz, Andreas, Noboru Kuboyama, Gunter Hempelmann, and Werner Vogel. "Complex Blockade of TTX-Resistant Na+ Currents by Lidocaine and Bupivacaine Reduce Firing Frequency in DRG Neurons." Journal of Neurophysiology 79, no. 4 (April 1, 1998): 1746–54. http://dx.doi.org/10.1152/jn.1998.79.4.1746.

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Scholz, Andreas, Noboru Kuboyama, Gunter Hempelmann, and Werner Vogel. Complex blockade of TTX-resistant Na+ currents by lidocaine and bupivacaine reduce firing frequency in DRG neurons. J. Neurophysiol. 79: 1746–1754, 1998. Mechanisms of blockade of tetrodotoxin-resistant (TTXr) Na+ channels by local anesthetics in comparison with the sensitivity of tetrodotoxin-sensitive (TTXs) Na+ channels were studied by means of the patch-clamp technique in neurons of dorsal root ganglions (DRG) of rat. Half-maximum inhibitory concentration (IC50) for the tonic block of TTXr Na+ currents by lidocaine was 210 μmol/l, whereas TTXs Na+ currents showed five times lower IC50 of 42 μmol/l. Bupivacaine blocked TTXr and TTXs Na+ currents more potently with IC50 of 32 and 13 μmol/l, respectively. In the inactivated state, TTXr Na+ channel block by lidocaine showed higher sensitivities (IC50 = 60 μmol/l) than in the resting state underlying tonic blockade. The time constant τ1 of recovery of TTXr Na+ channels from inactivation at −80 mV was slowed from 2 to 5 ms after addition of 10 μmol/l bupivacaine, whereas the τ2 value of ∼500 ms remained unchanged. The use-dependent block of TTXr Na+ channels led to a progressive reduction of current amplitudes with increasing frequency of stimulation, which was ≤53% block at 20 Hz in 10 μmol/l bupivacaine and 81% in 100 μmol lidocaine. The functional importance of the use-dependent block was confirmed in current-clamp experiments where 30 μmol/l of lidocaine or bupivacaine did not suppress the single action potential but clearly reduced the firing frequency of action potentials again with stronger potency of bupivacaine. Because it was found that TTXr Na+ channels predominantly occur in smaller sensory neurons, their blockade might underlie the suppression of the sensation of pain. Different sensitivities and varying proportions of TTXr and TTXs Na+ channels could explain the known differential block in spinal anesthesia. We suggest that the frequency reduction at low local anesthetic concentrations may explain the phenomenon of paresthesia where sensory information are suppressed gradually during spinal anesthesia.
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Orhan, Ayse I., and Esra C. Tatli. "Evaluation of Root Canal Obturation Quality in Deciduous Molars with Different Obturation Materials: An In Vitro Micro-Computed Tomography Study." BioMed Research International 2021 (July 2, 2021): 1–6. http://dx.doi.org/10.1155/2021/6567161.

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Objective. To evaluate the voids in root canal treatment of deciduous molar canals using three obturating materials and two obturation systems using micro-CT. Study Design. Thirty freshly extracted deciduous molars were used in this study. The specimens were instrumented using a ProTaper Universal rotary instrument and randomly assigned into six groups ( n = 5 ). Mesiobuccal root canals were obturated using Ca(OH)2 and iodoform-Ca(OH)2 and ZOE cement. The materials were applied straight from the syringe up to the 2 mm coronal level of the apex. Subsequently, the Lentulo spiral and ultrasonic activation with endoactivator were used for obturation. All samples were scanned by micro-CT with 9.1 μm isotropic voxel resolution. The voids in cross-sectional images and 3D volumes of voids were measured. Differences among materials were statically evaluated ( p < 0.05 ). Results. All study groups showed voids. Ca(OH)2 and iodoform-Ca(OH)2 with ultrasonic activation produced fewer voids whereas the ZOE groups showed higher voids with statistical significance ( p < 0.05 ). Conclusions. Ca(OH)2 and iodoform-Ca(OH)2 with ultrasonic activation decrease void formation. Further studies should be done with other obturation techniques and materials for deciduous tooth root canal management.
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IYER, LAXMI R., KIRUTHIKA RAMANATHAN, and SHENG-UEI GUAN. "MULTI-LEARNER BASED RECURSIVE SUPERVISED TRAINING." International Journal of Computational Intelligence and Applications 06, no. 03 (September 2006): 429–49. http://dx.doi.org/10.1142/s1469026806001861.

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In this paper, we propose the multi-learner based recursive supervised training (MLRT) algorithm, which uses the existing framework of recursive task decomposition, by training the entire dataset, picking out the best learnt patterns, and then repeating the process with the remaining patterns. Instead of having a single learner to classify all datasets during each recursion, an appropriate learner is chosen from a set of three learners, based on the subset of data being trained, thereby avoiding the time overhead associated with the genetic algorithm learner utilized in previous approaches. In this way MLRT seeks to identify the inherent characteristics of the dataset, and utilize it to train the data accurately and efficiently. We observed that empirically MLRT performs considerably well as compared with RPHP and other systems on benchmark data with 11% improvement in accuracy on the SPAM dataset and comparable performances on the VOWEL and the TWO-SPIRAL problems. In addition, for most datasets, the time taken by MLRT is considerably lower than that of the other systems with comparable accuracy. Two heuristic versions, MLRT-2 and MLRT-3, are also introduced to improve the efficiency in the system, and to make it more scalable for future updates. The performance in these versions is similar to the original MLRT system.
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Wang, Wenzhao, Shi Tang, Cong Li, Jianan Chen, Hongfei Li, Yanlin Su, and Bin Ning. "Specific Brain Morphometric Changes in Spinal Cord Injury: A Voxel-Based Meta-Analysis of White and Gray Matter Volume." Journal of Neurotrauma 36, no. 15 (August 2019): 2348–57. http://dx.doi.org/10.1089/neu.2018.6205.

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