Axis Points Research Articles

啁啾脉冲高斯光束在大气湍流中的传输特性

Based on the extended Huygens-Fresnel principle, analytical expressions are derived for the cross-spectral density matrix of chirped pulsed Gaussian beams propagating in turbulent atmosphere, which are then numerically simulated. It is shown that there are blue shifts in the spectra of axis point when the spectral width of chirped pulsed Gaussian beams is more than a certain value of 0.336. The turbulence induces the decrease of relative frequency shift of on-axis spectra; the relative frequency shift of on-axis spectra increases nonlinearly with the increasing light source spectral width. Increasing the beam waist radius can inhibit the relative frequency shift and the beam broadening.

Effect of cell surface deformation on synaptic factor accumulation during the early stages of T cell activation

Paracrine transfer of chemical factors between two interacting cells is a fundamental biological signaling process that can mediate cell differentiation, proliferation or even cell death. A hallmark geometrical feature of such interactions is deformation due to the flattening of membranes at the interface, referred to here as the synaptic gap. Of particular interest here is the accumulation of synaptic factor during the early stages of cell activation when one cell (REC) does not have sufficient surface receptors to absorb/adsorb the factor emitted by the other (EMC). Since factor accumulation has been conjectured to play an important role in cell activation, as in any reactive system, whether chemical or biological, an estimate of concentrations is essential for understanding the process. The purpose of this work is to provide just such an estimate by taking an engineering approach to this biological problem. In this regard, instead of providing a comprehensive “model” for paracrine delivery, the analysis is a solution of the quasi-steady diffusion equation in and around the interacting cells as a function of the degree of deformation and the kinetics of emission. Using a singularity method, it is found that, depending on the emission rate, cell deformation can lead to synaptic factor concentrations that are more than an order of magnitude higher than cells that retain a spherical shape. Analytical expressions for the radial variation of factor concentration within the gap are also derived. These analytical expressions, however, only provide the concentration difference between the synaptic axis and edge points but are nevertheless useful for estimating synaptic behavior and for validation of the computational method. The results also highlight the importance of deformation on paracrine signaling and indicate a mechanism by which cells can increase the range and function of transmitted factor by geometric alteration of the interface. While T cell activation is of primary interest, the analysis is cast in general terms so it can be applied to other non-absorbing RECs.

Space luminous environment adaptability of missile-borne star sensor

To solve the problem of stray interference to star point target identification while a star sensor imaging to the sky, a study on space luminous environment adaptability of missile-borne star sensor was carried out. By Plank blackbody radiation law and some astronomic knowledge, irradiancies of the stray at the star sensor working height were estimated. By relative astrophysical and mathematics knowledge, included angles between the star sensor optical axis point and the stray at any moment were calculated. The calculation correctness was verified with the star map software of Stellarium. By combining the upper analysis with the baffle suppression effect, a real-time model for space luminous environment of missile-borne star sensor was proposed. By signal-noise rate (SNR) criterion, the adaptability of missile-borne star sensor to space luminous environment was studied. As an example, a certain type of star sensor was considered when imaging to the starry sky on June 22, 2011 (the Summer Solstice) and September 20, 2011 (August 23 of the lunar year, last quarter moon) in Beijing. The space luminous environment and the adaptability to it were simulated and analyzed at the star sensor working height. In each period of time, the stray suppression of the baffle is analyzed by comparing the calculated included angle between the star sensor optical axis point and the stray with the shielded provided by system index. When the included angle is larger than the shielded angle and less than 90°, the stray is restrained by the baffle. The stray effect on star point target identification is analyzed by comparing the irradiancy of 6 magnitude star with that of the stray on star sensor sensitization surface. When the irradiancy of 6 magnitude star is 5 times more than that of the stray, there is no effect on the star point target identification. The simulation results are identical with the actual situation. The space luminous environment of the missile-borne star sensor can be estimated real-timely by this model. The adaptability of the star sensor to space luminous environment can be analyzed conveniently. A basis for determining the relative star sensor indexes, the navigation star chosen strategy and the missile launch window can be provided.

Assessing the AP Position of Maxillary Central Incisor using Forehead: A Smiling Profile Photographic Study

Aim: To evaluate and compare the anteroposterior position of permanent maxillary central incisor in profile in relation to the forehead inclination and prominence in adult (18-25 years) females of Maharashtra population. Materials and methods: The control sample ( N = 100) consisted of adult females (18-25 years of age) with optimum facial balance showing a pleasing profile compared with study sample (100 adult female patients of 18-25 years) seeking orthodontic treatment. All smiling profile images had the maxillary central incisors and the forehead in full view. The images were adjusted and rotated to the upright head position. Reference lines were drawn to measure the anteroposterior positions of the maxillary central incisors as well as forehead inclinations. Results: Strong correlation exists between positions of maxillary central incisor relative to forehead inclination in control group. In study group it is insignificant. It means that if position of maxillary central incisor relative to ‘forehead’s facial axis (FFA) point’ changes the forehead inclination also changes. The most esthetic maxillary central incisor position between FFA point and glabella was highest in the control sample (94%). Conclusion: The forehead is a useful landmark for assessing the facial profile for adult Maharashtra females as it relates to A-P maxillary central incisor position. Smiling profile photograph can be useful additional diagnostic tool for determining esthetic position of maxillary central incisors in the face.

Microstructure evolution in pure titanium during warm deformation by combined rolling processes

The constitutive analysis of stress–strain state by the finite element method was carried out by using the LS-DYNA software for the axis and surface points of rods of commercially pure titanium VT1-0, which were thermomechanically treated by consequent screw rolling and shape rolling at temperatures of 723 and 623K, respectively. The features of plastic strain distribution in cross section of workpiece, the strain rate evolution in the axis and surface points and the amount of adiabatic heat were considered. The stress state was revealed in terms of stress state factors and directing stress tensors during processing time. The microstructure evolution was studied by the electron backscattering diffraction method and analyzed using the TSL OIM software. The mechanisms of grain refinement, which were controlled by dynamic recrystallization, and the effect of nonhomogeneous stress–strain state in the axis and surface areas were discussed based on the analysis of strain hardening mechanisms, Schmidt factor and JMAK equations.

Research on 3D medial axis transform via the saddle point programming method

The present paper investigates the 3D medial axis transform of objects bounded by freeform surfaces via the saddle point programming method, a mathematical programming approach used to identify the saddle points of a function. After exploring the local geometry and saddle point property of 3D medial axis transform, the mathematical programming method is employed to construct the saddle point programming models. Based on the optimality conditions that the optimal solutions should satisfy, a generic algorithm for computing various medial axis points is developed. In order to identify the junction points and localize the problem, the boundary and the skeletal curves are divided into skeletal segments, and it is proved to be efficient and accurate by numerical examples.

재발한 간담도암 환자에서 시행 한 high-dose-rate intraluminal brachytherapy의 유용성 및 재현성 평가

General treatment for cholangiocarcinoma is complete surgical resection. However recurrence is common in those patients. In most of cases the purpose of the treatment for patients with recurrent is palliative. Therefore we adopt intraluminal catheter to treat a recurrent patient with high-dose-rate intraluminal brachytherapy. This study aims to evaluate the treatment procedure and set-up reproducibility of intraluminal brachytherapy in the recurrent patient. Study patient was diagnosed at rcT1N0M0 and undergone intraluminal brachytherapy after Arrow Sheath insertion. 3 Gy was delivered in every fraction with a total dose of 30 Gy. We planned dose normalization at distal, proximal and central axis point of narrowed bile duct far from 1 cm. To evaluate set-up reproducibility, we measured distance between distal, proximal treatment target volume point and anterior surface of the thoracic vertebral body respectively for five times before every treatment with dummy seed insertion. Mean distance between distal, proximal treatment target volume point and anterior surface of 10th and 11th thoracic vertebral bodies is 0.5 cm, 6.1 cm and standard deviation is 0.06, 0.08 respectively. In addition, set-up reproducibility was maintained significantly. The patient has been alive with no evidence of disease recurrence for more than a year and has not yet reported severe complications. In conclusion, high-dose-rate intraluminal brachytherapy for unresectable recurrence of cholangiocarcinoma maintains high set-up reproducibility without severe side effects.

Effect of hot rolling by screw mill on microstructure of a Ti-6Al-4V titanium alloy

The constitute analysis of stress–strain state by the finite element method was carried out by using LS-DYNA software for the axis and surface points of bars of titanium alloy Ti-6Al-4V with lamellar microstructure state, which were processed by screw rolling at a temperature of 940°C with reduction in area of 1.25 and 1.56. The features of screw rolling method that promoted workability of material were investigated. The rolling was performed with 6 passes. Rolling bar was reheated to rolling temperature between each passes for 5 min. The microstructure changes were assessed by light and scanning electron microscopy and quantitative microscopy analysis after each pass of rolling. The different types of deformations (monotonic and cyclic) having the strong influence on microstructures of considered points in the rolled bars are explained. The kinetic of globular structure formation during rolling to total reduction in area of 3.8 was clarified in cross section of bar.

Selective focusing of electrons and holes in a graphene-based superconducting lens

We show that a graphene pnp junction with a central superconducting electrode acts as a Veselago lens for incoming electrons by focusing them and their phase-conjugated counterpart (holes) into different points of the optical axis. This selective focusing suggested by a simple trajectory analysis is confirmed by fully microscopic calculations. Although the focusing pattern is degraded by deviations from the ideal conditions, we show that it remains visible for a wide range of parameters. We discuss how this property can be useful for the detection of entangled electron pairs.

The cosmic web and the orientation of angular momenta

ABSTRACT We use a 64 h−1 Mpc dark-matter-only cosmological simulation to examine the large-scale orientation of haloes and substructures with respect to the cosmic web. A web classification scheme based on the velocity shear tensor is used to assign to each halo in the simulation a web type: knot, filament, sheet or void. Using ∼106 haloes that span ∼3 orders of magnitude in mass, the orientation of the halo's spin and the orbital angular momentum of subhaloes with respect to the eigenvectors of the shear tensor is examined. We find that the orbital angular momentum of subhaloes tends to align with the intermediate eigenvector of the velocity shear tensor for all haloes in knots, filaments and sheets. This result indicates that the kinematics of substructures located deep within the virialized regions of a halo is determined by its infall which in turn is determined by the large-scale velocity shear, a surprising result given the virialized nature of haloes. The non-random nature of subhalo accretion is thus imprinted on the angular momentum measured at z= 0. We also find that the haloes’ spin axis is aligned with the third eigenvector of the velocity shear tensor in filaments and sheets: the halo spin axis points along filaments and lies in the plane of cosmic sheets.

Determination of spin rate and axes with an instrumented cricket ball

An instrumented cricket ball was developed with three single-axis rate gyros with a measurement range of ±350 rad/s (55.56 rps). The gyros, a miniature data logger and a battery were incorporated into a CNC machined ball with a seam. The data were collected at 500Hz and downloaded via the logger's USB port. The gyros were calibrated before inserting them into the ball. The output data provided the spin rates about all 3 axes, from which the resultant spin rate and the position of the spin axis were calculated. The axis was displayed as the axis point, the intersection of the axis with the surface of the ball, as well as 3D visualization of the ball and the spin axis surface (movement of the axis with time). The initial spin rate of the ball thrown by two subjects ranged between 10.5 rps and 18.4 rps. The spin decay ranged between 0.002 and 0.584 rev/s2 and was always linear. The spin axis, initially perpendicular to the plane of the seam can show considerable deviation towards the seam. The smart cricket ball is an invaluable tool for training and characterization of bowling deliveries.

In-vitro study on the accuracy of a simple-design CT-guided stent for dental implants

PurposeAn individual surgical stent fabricated from computed tomography (CT) data, called a CT-guided stent, would be useful for accurate installation of implants. The purpose of the present study was to introduce a newly developed CT-guided stent with a simple design and evaluate the accuracy of the stent placement.Materials and MethodsA resin template was fabricated from a hog mandible and a specially designed plastic plate, with 4 metal balls inserted in it for radiographic recognition, was attached to the occlusal surface of the template. With the surgical stent applied, CT images were taken, and virtual implants were placed using software. The spatial positions of the virtually positioned implants were acquired and implant guiding holes were drilled into the surgical stent using a specially designed 5-axis drilling machine. The surgical stent was placed on the mandible and CT images were taken again. The discrepancy between the central axis of the drilled holes on the second CT images and the virtually installed implants on the first CT images was evaluated.ResultsThe deviation of the entry point and angulation of the central axis in the reference plane were 0.47±0.27 mm, 0.57±0.23 mm, and 0.64±0.16°, 0.57±0.15°, respectively. However, for the two different angulations in each group, the 20° angulation showed a greater error in the deviation of the entry point than did the 10° angulation.ConclusionThe CT-guided template proposed in this study was highly accurate. It could replace existing implant guide systems to reduce costs and effort.

Differential optics for illumination design in the presence of caustics

Alternatively to using time-consuming Monte-Carlo simulations the irradiation at a target plane can also be calculated by differential optics methods. In the case of caustics, these methods yield to infinite irradiance and its results are not directly comparable to those of Monte-Carlo simulations. In this paper, a differential based algorithm for an on axis point source and a rotationally symmetric optical system is presented, which yields to the same results as a Monte-Carlo simulation. However, the differential optical methods are about three orders of magnitude faster than the latter one, thus allowing fast trial and error design of such kind of illumination systems. An applet is presented that uses sliders to change the shape of the lens and other properties of the illumination system whereas the irradiance profile is nearly immediately perceived. For beginners in the field, this does not only accelerate the design process itself but also the learning process is improved considerably. Some extensions and special cases are shortly discussed.

Near-perfect Collimation of Wide-Field Cassegrain Telescopes

ABSTRACTI describe a simple new method for collimating a Cassegrain telescope that gives near-perfect correction over a wide field of view. This method was used to collimate the 6.5 m MMT in 2002 with remarkably good results. The first step is to point the primary mirror accurately at an object. When the M1 optical axis points exactly toward an object, it cannot contribute pointing error, coma, or anamorphic aberration to the image field. If these are present, they must come from M2. Adjusting M2 to correct both pointing error and coma yields perfect collimation, canceling off-axis anamorphic aberrations. I present an analytical basis for this method and compare it with methods that measure off-axis image aberrations directly. In most cases, the technique described here gives better results. I describe the collimation procedure we used at MMT and suggest an easier way to adapt this method to other telescopes.

Plasma Bile Acids Are Associated with Energy Expenditure and Thyroid Function in Humans

Animal studies implicate a role of bile acids (BA) in thyroid-regulated energy expenditure (EE) via activation of the TGR-5/adenylate cyclase/deiodinase type 2 pathway. Here we investigated these possible associations in humans. EE, BA, and thyroid hormone status were assessed in 10 healthy subjects and eight patients with liver cirrhosis at baseline and after oral nutrition. In cirrhosis, blood was additionally sampled from the mesenteric vein and the radial artery. At baseline, BA and EE related positively (r = 0.648, P = 0.048 in healthy subjects; r = 0.833, P = 0.010 in cirrhosis; r = 0.556, P =0.017 in all), with the highest correlation with deoxycholic acid levels. The respiratory quotient associated negatively to baseline BA (all, r = -0.639, P = 0.004). Postprandially, serum TSH decreased in both groups (P < 0.05 each). In cirrhosis, the decrease of TSH after 60 min correlated to the meal-stimulated BA increase (r = -0.762, P = 0.028). To assess the mechanism involved, we studied a single human TSHoma and TαT1 mouse thyrotrope cells. In TSHoma cells, TGR-5 was predominantly expressed cytoplasmically, and in vitro stimulation with BA did not substantially alter cAMP or deiodinase type 2. Our data support a role of BA in human energy metabolism and in thyroid hormone control. Even though no convincing response to BA was demonstrated in TSHoma and TαT1 cells, the TSH decrease after a nutritional challenge suggests an interaction of BA on the set point of the thyroid axis.

LEGION-Based Automatic Road Extraction From Satellite Imagery

An automatic method for road extraction from satellite imagery is presented. The core of the proposed method is locally excitatory globally inhibitory oscillator networks (LEGION). The road extraction task is decomposed into three stages. The first stage is image segmentation by LEGION. In the second stage, the medial axis of each segment is computed, and the medial axis points corresponding to narrow regions are selected. The third is the road grouping stage. Alignment-dependent connections between selected points are established, and LEGION is utilized to group well-aligned points, which represent the extracted roads. Due to the selective gating mechanism of LEGION, different roads in an image are grouped separately. Road extraction results on synthetic and real images are presented. A comparison with other methods shows that the proposed method produces very competitive extraction results.

New clinical classification of dental arch form using facial axis points derived from three-dimensional models

Abstract Introduction: The purpose of the present study was to use facial axis (FA) points to classify dental arch form generated from an analysis of 3-D virtual models of a sample of normal occlusions. A secondary aim was to introduce a new arch form template based on this classification for clinical application. Methods: One hundred and twenty five plaster models of Class I occlusions were 3-D scanned (Orapix Co., Ltd, Seoul, Korea) and FA points digitized on the virtual models using Rapidform 2006 software (INUS Technology Inc., Seoul, Korea). Following intercanine and intermolar arch width and depth measurements, K-means cluster analysis was applied on 77 cases (Dataset 1) to classify the sample into arch form types. A curve of best fit of the mean arch form of each type was generated. The remaining 48 cases (Dataset 2) were mapped into the clusters and a multivariate test was performed to assess the differences among the clusters. Results: Classification into five clusters demonstrated maximum inter-cluster distance in the arch parameters and produced the most homogeneous cluster size. The differences between the 5 cluster types were statistically but not clinically significant and so they were recombined to form three clusters representing ‘narrow’, ‘moderate’ and ‘wide’ arch forms. Conclusions: A template with three arch form types based on anterior and posterior dimensions has been proposed through 3-D analysis of FA points for more accurate arch form identification and arch wire selection.

SU‐E‐T‐348: Commissioning of An Independent Monitor Unit Verification Program (RadCalc Version 6.1) in Photon Point Dose Calculation

Purpose: To commissioningRadCalc program for secondary point dose check in conventional 2D and 3DCRT calculation techniques. Methods: Test plans for 6 MV and 10 MV photon beams with conventional and 3DCRT planwere created inRadCalc program.Field was varied with a range of field sizes and modifier techniques referred to IAEA‐TECDOC‐1583 with central axis and off central axis calculation points. The measured dose for each field was then compared to the calculated dose (RadCalc program and Eclipse treatment planning system). Results: In conventional field validation,RadCalc shows good agreement with measured doses.For open and almost all wedge fields, RadCalccalculationagree with dose measurement within +/−1%. Differences of over 1% were found in maximum wedge fields and some half fields. However, the dose difference between calculation and measurementwas within +/−2% in all tests. In 3DCRT plan validation, the central axis point dose between calculation and measurement in all tests are agree within the IAEA‐TECDOC‐1583 criteria. When measured/ calculated dose points were in non‐tissue equivalent such as lung and bone which were off central axis situation, dose difference is more than +/−10%. Unfortunately if measured/ calculated dose points areoutside the field (scatter dose), the result cannot be validated. Part of this large difference between two calculated and measured can be the volume effect of the chamber.In comparison between dose calculated by RadCalc and Eclipse, overall results show dose difference within +/−5%. Conclusions: RadCalc program can be used as a point dose calculation check in conventional 2D and 3DCRT techniques.

Study of the distribution of microvessels in normal and pathologic prostate using an information-based similarity analysis

Categorizing biologic signals by analysis of symbolic sequences was employed in the study of prostate microvessels. The estimates of the volume fraction of the vessels immunostained to Factor-VIII was mapped to binary sequences. The distance between sequences was estimated by comparing the rank and frequency of repetitive elements. These measurements were applied to detect whether there are unique microvascular patterns for each individual, and to search for patterns describing prostate microvessels of different conditions. Normal prostate, benign prostate hyperplasia and prostate carcinoma groups were studied. All the specimens were immunostained to F-VIII and strips formed by adjacent quadrats were explored. At each point of the long axis of the strip, the V(V) F-VIII was calculated. These values were processed with the information-based similarity software to estimate the dissimilarity between two space series. The following comparisons were carried out: intrasubject versus intragroup distances; intragroup distances among the groups studied and intergroup distances. The distance defined between a vessels immunostained to Factor-VIII space series and its randomized surrogate was considered as an index of the nonrandomness of the space series. These indices were compared for all the groups. We conclude that (a) The information-based similarity analysis can be adapted to vessels immunostained to Factor-VIII space series from prostate microvessels. (b) There are no unique microvascular patterns associated with each individual. (c) There are characteristic patterns describing the microvessels from normal prostate, benign prostate hyperplasia and carcinoma. (d) This method is able to account for the differences between prostate cancer and both normal and benign prostate conditions, with respect to the microvessel patterns.

Fast equal and biased distance fields for medial axis transform with meshing in mind

A method for robust and efficient medial axis transform (MAT) of arbitrary domains using distance solutions (or level sets) is presented. The distance field, d, is calculated by solving the hyperbolic-natured eikonal equation. The solution is obtained on Cartesian grids. Both the fast-marching method (FMM) and fast-sweeping method (FSM) are used to calculate d. Medial axis point clouds are then extracted based on the distance solution via a simple criterion: the Laplacian or the Hessian determinant of d( x). These point clouds in the pixel/voxel space are further thinned to single pixel wide so that medial axis curves or surfaces can be connected and splined. As an alternative to other methods, the current d-MAT procedure bypasses difficulties that are usually encountered by pure geometric methods (e.g. the Voronoi approach), especially in three dimensions, and provides better accuracy than pure thinning methods. It is also shown that the d-MAT approach provides the potential to sculpt/control the MAT form for specialized solution purposes. Various examples are given to demonstrate the current approach.