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Zheyuan Zhu, Shuo Pang
PURPOSE: X-ray coherent scattering tomography is a powerful tool in discriminating biological tissues and bio-compatible materials. Conventional X-ray scattering tomography framework can only resolve isotropic scattering profile under the assumption that the material is amorphous or in powder form, which is not true especially for biological samples with orientation-dependent structure. Previous tomography schemes based on X-ray coherent scattering failed to preserve the scattering pattern from samples with preferred orientations, or required elaborated data acquisition scheme, which could limit its application in practical settings...
February 15, 2018: Medical Physics
Nashat Faried, Ahmed Morsy, Aya M Hussein
In 1960, Dvoretzky proved that in any infinite dimensional Banach space X and for any [Formula: see text] there exists a subspace L of X of arbitrary large dimension ϵ -iometric to Euclidean space. A main tool in proving this deep result was some results concerning asphericity of convex bodies. In this work, we introduce a simple technique and rigorous formulas to facilitate calculating the asphericity for each set that has a nonempty boundary set with respect to the flat space generated by it. We also give a formula to determine the center and the radius of the smallest ball containing a nonempty nonsingleton set K in a linear normed space, and the center and the radius of the largest ball contained in it provided that K has a nonempty boundary set with respect to the flat space generated by it...
2018: Journal of Inequalities and Applications
Samuel Ojosnegros, Francesco Cutrale, Daniel Rodríguez, Jason J Otterstrom, Chi Li Chiu, Verónica Hortigüela, Carolina Tarantino, Anna Seriola, Stephen Mieruszynski, Elena Martínez, Melike Lakadamyali, Angel Raya, Scott E Fraser
Eph receptor signaling plays key roles in vertebrate tissue boundary formation, axonal pathfinding, and stem cell regeneration by steering cells to positions defined by its ligand ephrin. Some of the key events in Eph-ephrin signaling are understood: ephrin binding triggers the clustering of the Eph receptor, fostering transphosphorylation and signal transduction into the cell. However, a quantitative and mechanistic understanding of how the signal is processed by the recipient cell into precise and proportional responses is largely lacking...
December 12, 2017: Proceedings of the National Academy of Sciences of the United States of America
Inseong Jo, Seokho Hong, Minho Lee, Saemee Song, Jin-Sik Kim, Alok K Mitra, Jaekyung Hyun, Kangseok Lee, Nam-Chul Ha
The MacAB-TolC tripartite efflux pump is involved in resistance to macrolide antibiotics and secretion of protein toxins in many Gram-negative bacteria. The pump spans the entire cell envelope and operates by expelling substances to extracellular space. X-ray crystal and electron microscopic structures have revealed the funnel-like MacA hexamer in the periplasmic space and the cylindrical TolC trimer. Nonetheless, the inner membrane transporter MacB still remains ambiguous in terms of its oligomeric state in the functional complex...
December 16, 2017: Biochemical and Biophysical Research Communications
Luning Su, Wei Li, Mingxuan Wu, Yun Su, Chongling Guo, Ningjuan Ruan, Bingxin Yang, Feng Yan
Lobster-eye optics is widely applied to space x-ray detection missions and x-ray security checks for its wide field of view and low weight. This paper presents a theoretical model to obtain spatial distribution of focusing efficiency based on lobster-eye optics in a soft x-ray wavelength. The calculations reveal the competition mechanism of contributions to the focusing efficiency between the geometrical parameters of lobster-eye optics and the reflectivity of the iridium film. In addition, the focusing efficiency image depending on x-ray wavelengths further explains the influence of different geometrical parameters of lobster-eye optics and different soft x-ray wavelengths on focusing efficiency...
August 1, 2017: Applied Optics
Yanxia Tang, Jinyu Guan, Yongchun Xu, Yongfu Su
Let K be a nonempty closed convex and bounded subset of a reflexive Banach space X. Let [Formula: see text] be N-variables monotone demi-continuous mappings from [Formula: see text] into X. Then: (1) the system of multivariate variational inequalities [Formula: see text] has a solution [Formula: see text]; (2) the set of solutions of this system of multivariate variational inequalities is closed convex in [Formula: see text]; (3) if [Formula: see text] are also strictly monotone, this system of multivariate variational inequalities has a unique solution...
2017: Journal of Inequalities and Applications
Jin Huan Li, Bo Ling, San Yang Liu
A new constant [Formula: see text] is introduced into any real [Formula: see text]-dimensional symmetric normed space X. By virtue of this constant, an upper bound of the geometric constant [Formula: see text], which is used to measure the difference between Birkhoff orthogonality and isosceles orthogonality, is obtained and further extended to an arbitrary m-dimensional symmetric normed linear space ([Formula: see text]). As an application, the result is used to prove a special case for the reverse Hölder inequality...
2017: Journal of Inequalities and Applications
Isak Buhl-Mortensen, Marius de Leeuw, Asger C Ipsen, Charlotte Kristjansen, Matthias Wilhelm
We initiate the calculation of loop corrections to correlation functions in 4D defect conformal field theories (dCFTs). More precisely, we consider N=4 SYM theory with a codimension-one defect separating two regions of space, x_{3}>0 and x_{3}<0, where the gauge group is SU(N) and SU(N-k), respectively. This setup is made possible by some of the real scalar fields acquiring a nonvanishing and x_{3}-dependent vacuum expectation value for x_{3}>0. The holographic dual is the D3-D5 probe brane system where the D5-brane geometry is AdS_{4}×S^{2} and a background gauge field has k units of flux through the S^{2}...
December 2, 2016: Physical Review Letters
Daisuke Kato, Mika Baba, Kota S Sasaki, Izumi Ohzawa
The key problem of stereoscopic vision is traditionally defined as accurately finding the positional shifts of corresponding object features between left and right images. Here, we demonstrate that the problem must be considered in a four-dimensional parameter space; with respect not only to shifts in space (X, Y), but also spatial frequency (SF) and orientation (OR). The proposed model sums outputs of binocular energy units linearly over the multi-dimensional V1 parameter space (X, Y, SF, OR). Theoretical analyses and physiological experiments show that many binocular neurons achieve sharp binocular tuning properties by pooling the output of multiple neurons with relatively broad tuning...
June 19, 2016: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Yuri S Semenov, Artem S Novozhilov
A two-valued fitness landscape is introduced for the classical Eigen's quasispecies model. This fitness landscape can be considered as a direct generalization of the so-called single- or sharply peaked landscape. A general, non-permutation invariant quasispecies model is studied, and therefore the dimension of the problem is [Formula: see text], where N is the sequence length. It is shown that if the fitness function is equal to [Formula: see text] on a G-orbit A and is equal to w elsewhere, then the mean population fitness can be found as the largest root of an algebraic equation of degree at most [Formula: see text]...
May 2016: Bulletin of Mathematical Biology
Y Abdallah, A Micheal
Teratoma in the nasopharynx is one of the rare causes for nasal symptoms in the newborn. The present report was on a term "neonate" who had respiratory distress from a hidden teratoma. Cheaper and readily available investigation modalities including postnasal space X-ray and examination under anesthesia revealed nothing. A postnasal space computed tomography also revealed nothing. Magnetic resonance imaging revealed a mass which was resected endoscopically and histology revealed an immature teratoma. Herein, we present the case, management challenges and literature review to emphasis that negative investigations with persistent nasal symptoms should prompt further evaluation and teratoma should be considered when encountering newborn with nasal symptoms without obvious cause...
January 2016: Annals of Medical and Health Sciences Research
Xin Wu, Guo-yuan Liu, Yong-lian Jiang
PURPOSE: To investigate the differences in anchorage effects between micro-implants and J hook in treating patients with Class II division 1 maxillary protrusion. METHODS: Thirty-one cases of adult patients with Class II division 1 maxillary protrusion were treated. They were divided into 2 groups depending on their selection. The first group included 17 patients for micro-implant anchorage, who adopted micro-implant and sliding mechanism to close maxillary extraction space and depress the mandibular molar...
October 2015: Shanghai Kou Qiang Yi Xue, Shanghai Journal of Stomatology
R Duits, U Boscain, F Rossi, Y Sachkov
To model association fields that underly perceptional organization (gestalt) in psychophysics we consider the problem P curve of minimizing [Formula: see text] for a planar curve having fixed initial and final positions and directions. Here κ(s) is the curvature of the curve with free total length ℓ. This problem comes from a model of geometry of vision due to Petitot (in J. Physiol. Paris 97:265-309, 2003; Math. Inf. Sci. Humaines 145:5-101, 1999), and Citti & Sarti (in J. Math. Imaging Vis. 24(3):307-326, 2006)...
2014: Journal of Mathematical Imaging and Vision
Nazanin Samadi, Bassey Bassey, Mercedes Martinson, George Belev, Les Dallin, Mark de Jong, Dean Chapman
The stability of the photon beam position on synchrotron beamlines is critical for most if not all synchrotron radiation experiments. The position of the beam at the experiment or optical element location is set by the position and angle of the electron beam source as it traverses the magnetic field of the bend-magnet or insertion device. Thus an ideal photon beam monitor would be able to simultaneously measure the photon beam's position and angle, and thus infer the electron beam's position in phase space...
July 2015: Journal of Synchrotron Radiation
John Z Kiss
The growth and development of plants during spaceflight have important implications for both basic and applied research supported by NASA and other international space agencies. While there have been many reviews of plant space biology, the present chapter attempts to fill a gap in the literature on the actual process and methods of performing plant research in the spaceflight environment. The author has been a principal investigator on six spaceflight projects and has another two space experiments in development...
2015: Methods in Molecular Biology
A M Barragán, S Differding, G Janssens, J A Lee, E Sterpin
PURPOSE: To prove the ability of protons to reproduce a dose gradient that matches a dose painting by numbers (DPBN) prescription in the presence of setup and range errors, by using contours and structure-based optimization in a commercial treatment planning system. METHODS: For two patients with head and neck cancer, voxel-by-voxel prescription to the target volume (GTVPET) was calculated from (18)FDG-PET images and approximated with several discrete prescription subcontours...
April 2015: Medical Physics
Hüseyin Çakalli, Sibel Ersan
A function f defined on a subset E of a 2-normed space X is strongly lacunary ward continuous if it preserves strongly lacunary quasi-Cauchy sequences of points in E; that is, (f(x k)) is a strongly lacunary quasi-Cauchy sequence whenever (x k) is strongly lacunary quasi-Cauchy. In this paper, not only strongly lacunary ward continuity, but also some other kinds of continuities are investigated in 2-normed spaces.
2014: TheScientificWorldJournal
Jakob Löber, Harald Engel
We present a method to control the position as a function of time of one-dimensional traveling wave solutions to reaction-diffusion systems according to a prespecified protocol of motion. Given this protocol, the control function is found as the solution of a perturbatively derived integral equation. Two cases are considered. First, we derive an analytical expression for the space (x) and time (t) dependent control function f(x,t) that is valid for arbitrary protocols and many reaction-diffusion systems. These results are close to numerically computed optimal controls...
April 11, 2014: Physical Review Letters
Kelsey A Nestor, Jacob D Jones, Christopher R Butson, Takashi Morishita, Charles E Jacobson, David A Peace, Dennis Chen, Kelly D Foote, Michael S Okun
BACKGROUND: Effective target regions for deep brain stimulation (DBS) in Parkinson's disease (PD) have been well characterized. We sought to study whether the measured Cartesian coordinates of an implanted DBS lead are predictive of motor outcome(s). We tested the hypothesis that the position and trajectory of the DBS lead relative to the mid-commissural point (MCP) are significant predictors of clinical outcomes. We expected that due to neuroanatomical variation among individuals, a simple measure of the position of the DBS lead relative to MCP (commonly used in clinical practice) may not be a reliable predictor of clinical outcomes when utilized alone...
2014: PloS One
Kartik Ayyer, Hugh T Philipp, Mark W Tate, Veit Elser, Sol M Gruner
Schemes for X-ray imaging single protein molecules using new x-ray sources, like x-ray free electron lasers (XFELs), require processing many frames of data that are obtained by taking temporally short snapshots of identical molecules, each with a random and unknown orientation. Due to the small size of the molecules and short exposure times, average signal levels of much less than 1 photon/pixel/frame are expected, much too low to be processed using standard methods. One approach to process the data is to use statistical methods developed in the EMC algorithm (Loh & Elser, Phys...
February 10, 2014: Optics Express
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