Sets Of Rods Research Articles

Development of a novel phantom for tau PET imaging

PurposeThe cortical uptake of tau positron emission tomography (PET) tracers corresponds to the Braak stage and reflects the distribution and progression of tau neurofibrillary tangles. The present study aimed to develop and validate the basic performance of a novel tau PET phantom, as well as to establish standard test procedures and analytical methods. MethodsThe tau PET phantom consisted of a brain simulation section simulated medial temporal lobe region and resolution and uniformity sections. The brain simulation section and hot rods and uniformity section contained 4 and 2 kBq/mL of 18F, respectively and images were acquired three times for 20 min with a PET/CT scanner. The resolution section was visually assessed with two sets of hot and cold rods. Recovery coefficients (RCs) as a quantitative value and coefficient of variation (CV) as image noise were determined based on the brain simulation and the uniformity section, respectively. ResultsPreparation of activity in the phantom was repeatable among three measurements. The quality of images in the brain simulation and uniformity section with the rods was good. The 5- or 6-mm rods were detected separately. The mean RCs calculated based on the VOI template were between 0.75 and 0.83. The CV at the center slice of uniformity section was 5.54%. ConclusionsWe developed a novel tau PET phantom to assess quantitative value, image noise, and detectability and resolution from brain simulation section, uniformity section, and rods, respectively. This phantom will contribute to the standardization and harmonization of tau PET imaging.

Stability of the Fe3O4 (√2 x √2)R 45° Surface in 0.1 M NaOH Investigated by High-Energy Surface X-Ray Diffraction

Transition metal oxides, especially Fe, Co, and Ni oxides, are of great interest as electrocatalysts for the oxygen evolution reaction (OER) in alkaline solution. However, detailed data on the atomic-scale oxide-electrolyte interface structure of these systems are rare. We present studies of a model oxide electrocatalyst, -reconstructed Fe3O4(001). This oxide surface has been extensively investigated under ultrahigh vacuum (UHV) conditions, leading to a detailed understanding of its atomic structure [2]. In previous in situ surface X-ray diffraction studies, we demonstrated that the reconstructed surface can survive transfer into electrochemical environment and determined the stability of the reconstruction as a function of potential [2]. Specifically, we showed that the ()R45° reconstructed Fe3O4(001) surface can be transferred into 0.1 M NaOH at 0.2 V vs. Ag/AgCl while maintaining surface structure and that the reconstruction is irreversibly lifted at sufficiently negative potentials.Here, we present more detailed in situ studies of this system, using the novel technique of High-Energy Surface X-Ray Diffraction (HESXRD) [3,4]. This technique enabled us to measure rapidly a huge reciprocal space volume, which allows to obtain very large sets of crystal truncation rods (CTRs) that can be analysed by surface crystallographic methods. These data provide detailed insights into the temporal stability of the surface at fixed potentials as well as potential-dependent changes in surface structure.In the experiments the Fe3O4(001) single crystal samples were prepared by sputtering and annealing in UHV, followed by sample transfer into the hanging-meniscus cell employed for the HESXRD studies. A new experimental procedure allowed to reduce the time of sample transfer and establishment of potential control to below one minute.The in situ HESXRD measurements were performed at beamline P21.2 of PETRA III at DESY. 7 symmetrically independent CTRs and 2 ()R45° fractional order rods could be measured. These data enabled detailed comparison of the oxide-electrolyte interface with the surface structure under UHV conditions [1]. The potential-dependent data indicate clear structural changes when applying more positive or more negative potentials than 0.2 V vs. Ag/AgCl, as illustrated in part A and B of Fig. 1. However, all surface structures were stable at constant potential over several hours, as indicated in part C of Fig. 1. The quality of the obtained results allows to determine quantitative analysis of the interface structure. First results of this analysis will be presented.We gratefully acknowledge financial support by the German ministry of Science and Education (BMBF) via projects 05K19FK3 and 05K22FK1.

Hardness prediction in the upsetting process of Al%ZrO2—an approach to machine learning using regression and classification models

The current study focuses on the prediction of metal hardness distribution in upsetting tests for different compositions of ZrO2 embedded with an aluminum matrix using machine learning algorithms and finite element (FE) analysis. The mass fraction of the ZrO2 particles varied from 4% to 8%, and three sets of solid cylindrical rods with Al4%ZrO2, Al6%ZrO2, and Al8%ZrO2 were prepared using the stir casting method. The upsetting process was simulated, and an equation for predicting hardness was developed from the equivalent strain distributions. Artificial neural networks (ANNs), multilinear regression (MLR) along with equations developed from FE analysis were used to train the model for regression analysis, considering the principal stresses, friction factor, anisotropy ratio, effective strain, and hoop strain as input and the magnitude of hardness as output parameters. Regression analysis reveals that ANN (tri-layer network), XGBoost, and MLR algorithms are the best suitable for the given data sets with a root mean square ( R2) greater than 0.95. XGBoost, ANN (narrow), and SVM are linear and are the most recommendable classifier algorithms for the current investigation. Hardness data from ring compression tests were used to validate the results obtained from the trained models with the test results.

Online Prediction Method of Molten Aluminium Height in Electrolytic Cell Based on Extreme Learning Machine with Kernel Function

An online prediction method of molten aluminium height is proposed based on extreme learning machine with kernel function (K-ELM). Firstly, relevant variables that can be measured online related to aluminium liquid fluctuations were obtained by analyzing the mechanism model of aluminium liquid fluctuations. Then, the online prediction method of molten aluminium height is proposed based on kernel function and ELM, which just use the anode-cathode voltage and the anode rod current data. Finally, the data collection and experiment of 3 sets of anode rods in the 200 kA series aluminium electrolytic cells are carried out on-site. The results show that the maximum absolute error is only 0.25 cm and relative error is less than 1.4%, which satisfied the production site requirements. Compared with existing methods, it has certain advantages in real-time and prediction accuracy and meets the real-time and accuracy requirements of the actual production process on-site.

Failure Assessment of Load-Stabilizing Rod in Heavy-Duty Truck Through CAE and Testing in Rough Road Conditions

The load-stabilizing (LS) rod is a part of heavy-duty mining vehicle front axle suspension system. The application of LS rod is essential in mining vehicle used predominantly for transportation of iron ore, coal, etc. from stockpile to storage yard. In this vehicle, two front axles are used for higher load capacity and better maneuverability. The load-stabilizing rod is one of the most critical components to support and stabilize the load between the two front axles. Computer-aided engineering (CAE) simulation has been used for stress analysis to evaluate the various forces influencing the failure of LS rod. Failure analysis is carried out for different rough road (RR) conditions. Road load data acquisition is conducted to validate the CAE results. Five sets of load-stabilizing rods were tested on different road test tracks in RR conditions. Strain gauges are used to measure the maximum stresses and tensile force induced in the LS rod. Fracture failure has been detected at the weaker section in the LS rod.

Unconventional light scattering from glassy photonic films and metasurfaces

The propagation of light through a random medium is an important problem in photonics. When the random fluctuations of the orientation for individual rods were introduced to the ideal woodpile photonic structure, a crossover from Laue diffraction to randomly scattered fields which is similar in appearance to speckle patterns was observed and investigated. Unexpected interplay between order and disorder was discovered from anisotropic glassy samples when orientational disorder was added only in one direction of square woodpile structure. It is found that the ordered sets of rods produced disordered patterns and vice versa the disordered sets of rods produced ordered patterns that continue to be bright and sharp with increasing disorder. To explain this effect, it was demonstrated theoretically and experimentally that the light scattering can be described purely in terms of the intersection points of the rods.

Damage modeling and critical damage evaluation of AA2014 cast alloy embedded with fly ash composite under upsetting

Abstract: Upsetting is one of the primary metal forming techniques and needs to be applied to reduce the cross section of the billets for further processing. Ductile fracture in metal upsetting process is an issue and depends on the material used and processing conditions. The current work focus is on the critical damage evaluation of AA2014 cast alloy embedded with fly ash composite. AA2014 alloy was heated to a pouring temperature of 750 ℃ and fly ash of 3% and 6% were added separately with AA2014 matrix material to prepare three sets of cast alloys namely pure AA2014, AA2014 + 3% fly ash, and AA2014 + 6% fly ash. After manufacturing three sets of rods from stir casting process, three sets of billets were machined to a height and diameter of 24 mm. Three sets of billets were compressed between rigid dies to different levels of strain until the initiation of fracture. Ductile fracture criterions were modeled to evaluate the critical damage value and fracture loci were constructed for different compositions.

Use of a Qualification Phantom for PET Brain Imaging in a Multicenter Consortium: A Collaboration Between the Pediatric Brain Tumor Consortium and the SNMMI Clinical Trials Network.

The purpose of this study was to assess image quality and quantitative brain PET across a multicenter consortium. Methods: All academic centers and children's hospitals in the Pediatric Brain Tumor Consortium (PBTC) scanned a phantom developed by the Society of Nuclear Medicine and Molecular Imaging Clinical Trials Network (SNMMI CTN) for the validation of brain PET studies associated with clinical trials. The phantom comprises 2 separate, fillable sections: a resolution/uniformity section and a clinical simulation section. The resolution/uniformity section is a cylinder 12.7 cm long and 20 cm in diameter; spatial resolution is evaluated subjectively with 2 sets of rods (hot and cold) of varying diameter (4.0, 5.0, 6.25, 7.81, 9.67, and 12.2 mm) and spacing (twice the rod diameter). The clinical simulation section simulates a transverse section of midbrain with ventricles and gray and white matter compartments. If properly filled, hot rods have a 4:1 target-to-background ratio, and gray-to-white matter sections have a 4:1 ratio. Uniformity and image quality were evaluated using the SUV in a small volume of interest as well as subjectively by 2 independent observers using a 4-point scale. Results: Eleven PBTC sites scanned the phantom on 13 PET scanners. The phantom's complexity led to suboptimal filling, particularly of the hot rod section, in 5 sites. The SUV in the uniformity section was within 10% of unity on only 5 of 13 scanners, although 12 of 13 were subjectively judged to have very good to excellent uniformity. Four of 6 hot rods were discernable by all 13 scanners, whereas 3 of 6 cold rods were discernable by only 5 scanners. Four of 13 scanners had a gray-to-white matter ratio between 3.0 and 5.0 (4.0 is truth); however, 11 of 13 scanners were subjectively judged to have very good or excellent image quality. Conclusion: Eleven sites were able to image a powerful phantom developed by the SNMMI CTN that evaluated image uniformity, spatial resolution, and image quality of brain PET. There was considerable variation in PET data across the PBTC sites, possibly resulting from variations in scanning across the sites due to challenges in filling the phantom.

Scattering of light from disordered photonic structures

We study theoretically and experimentally the scattering of light from ordered and disordered photonic structures. As an example, we consider a thin slab of a woodpile-type photonic crystal and introduce random fluctuations in the rod orientation, revealing a crossover from the Laue diffraction to the formation of speckle patterns. We observe a nontrivial interplay between order and disorder when the orientational disorder is added only in one direction of the square woodpile structure. Namely, ordered sets of rods produce disordered patterns and, vice versa, disordered sets of rods produce ordered patterns. We explain this effect theoretically and experimentally by the fact that light scatters only from the intersection points of different rods.

Surmounting the Learning Curve of Core Suture Placement with Tendon Repair Simulator.

Attaining competency in placement of core suture with adequate distance from juncture is a key skill for learners of tendon repair. Currently, this is most commonly practiced on animal models in wet laboratory environment. To improve accessibility and availability, we developed a tendon repair trainer that aims to guide learners in obtaining this key competency. A customized tendon dock was designed and manufactured with additive method that permits insertion of 6mm silicon tendon rods to simulate flexor tendon repair along a digit. Four residents, divided into two groups, were instructed to repair two sets of tendon rods (60 rods per resident) with Kessler suture loop placed at 10 mm from juncture (Group A: rods marked at 10 mm, Group B: unmarked rods). The main criterion for passing was a loop placed within 1 mm of the target distance (10 mm). At a second session, both groups repaired unmarked tendons, and these were marked based on similar criterion. At the first session, 100% of those who repaired marked rods (Group A) passed while 25% of unmarked rods (Group B) attained a pass. At the second session, where both groups repaired unmarked rods, residents from group A achieved a pass rate of 95% while group B achieved 33.3% pass. Learners who had previously repaired marked rods were able to retain their experience when repairing unmarked rods. This suggest that the proposed model may be a helpful adjunct to sharpen learners' skills prior to practicing tendon repairs in more costly animal or cadaveric models.

Acoustic responses of the composite sandwich plates with lattice truss core to the subsonic turbulent boundary layer

Acoustic responses of composite sandwich plates with lattice truss core to the subsonic turbulent boundary layer are investigated. The lattice truss core is composed of four sets of orthogonal stiffeners, two sets of oblique rods and one set of vertical columns, which establishes a significant transfer path of the reactive loadings. Bending and axial motion of the vertical columns makes a great impact on the power spectral density (PSD) of the transverse displacements for the sandwich plates with lattice truss core. The convective region of the high subsonic turbulent boundary layer pressure fluctuation spectra is the predominant vibrational source in the wide frequency bands, which makes the skin plate effectively radiate sound power into the mean air flow and the trim plate transmit sound waves into the static air by wavenumber conversion. Radiated acoustic power of skin plate is much larger than transmitted sound power of the trim plate and the sandwich plates can attenuate wave propagation of the airflow turbulent wall-pressure. The principal energy of the turbulent boundary layer wall-pressure for the water flow with a low speed can be transformed into the vibrational and acoustic energy of the sandwich plates in the low frequency band, to great extent.

SU‐E‐I‐39: Experimental Study On the Performance of the OMAR CT Artifact Correction Algorithm Near Titanium and Stainless Steel

Purpose: Implants with high atomic numbers produce star‐like artifacts in CT‐images. When coupled in pairs, a black window appears in between. The Philips OMAR algorithm approaches these artifacts by post processing the images. In this study, measurements were performed with radiochromic EBT2 films in order to verify, whether the OMAR algorithm contributes to the accuracy of treatment plans in implant regions. Methods: Two sets of titanium and stainless steel rods with diameters of 1inch and 0.5inch were centered in a water phantom either single or in pairs. The phantom was scanned in a Philips Bigbore Brilliance scanner, which provides the OMAR correction algorithm. A set of uncorrected CT data was kept in addition to the post processed data. The treatment plans were calculated with AAA in Eclipse. The Hounsfield units in the volume of the metal rods were set to match the relative electron density with the conversion table extended accordingly. A 10×12 field at 90 degrees gantry rotation and 400MU was calculated using on a 1mm grid. The plans were irradiated using a Varian Novalis‐TX linac with EBT3 films placed on the sides of the single rod setup or between the rods in the two rod setups. The FilmQA Pro Software was used for evaluation of the films. Results: With one inhomogeneity present in the phantom, the difference between the plans based on the uncorrected data and the plans based on the post processed data is small. With paired inhomogeneities and the associated increased artifact, the difference becomes more significant and the OMAR algorithm improves the accuracy. High Z scattering effects cause considerable deviation from the planned dose profiles near the rods. Conclusion: The OMAR‐algorithm improves the accuracy of the dose calculations. The dose profiles across implant regions are calculated accurately, if the Hounsfield units are defined accordingly.

Attitude control system of the first Russian nanosatellite TNS-0 no. 1

The results of designing the attitude control system of the first Russian nanosatellite TNS-0 no. 1 providing orientation of its longitudinal axis along the local geomagnetic field induction vector are presented. The system consists of a permanent magnet and two sets of hysteresis rods. The magnetic and geometric parameters of the magnet and rods are calculated. The influence of the permanent magnet field on the hysteresis rods and mutual influence of the rods in the case of compact satellite packaging are analyzed. Examples of calculations of transient processes and steady-state angular satellite motion are presented.

Protective Effects of Small Amounts of Bis(2-ethylhexyl)sulfosuccinate on the Helical Structures of Human and Bovine Serum Albumins in Their Thermal Denaturations

The protective effect of an anionic double-tailed surfactant, sodium bis(2-ethylhexyl)sulfosuccinate (AOT), on the structures of human serum albumin (HSA) and bovine serum albumin (BSA) in their thermal denaturations was examined by means of circular dichroism measurements. The structural changes of these albumins were reversible in the thermal denaturation below 50 degrees C, but became partially irreversible above this temperature. The effect was observed in the thermal denaturation above 50 degrees C. Although the helicity of HSA decreased from 66% to 44% at 65 degrees C in the absence of the surfactant, the decrement of it was restrained in the coexistence of AOT of extremely low concentrations. When the HSA concentration was 10 muM, the maximal protective effect appeared at 0.15 mM AOT. In the coexistence of the surfactant of this concentration, the helicity was maintained at 58% at 65 degrees C, increasing to the original value upon cooling to 25 degrees C. Beyond 0.15 mM AOT, the helicity sharply decreased until 3 mM AOT. A particular AOT concentration required to induce the maximal protective effect ([AOT]REQ) was examined at different HSA concentrations. [AOT]REQ shifted to higher values with an increase of the protein concentration. From the protein concentration dependences of [AOT]REQ, the maximal protection was estimated to require 8.0 and 5.0 AOT ions per a molecule of HSA and BSA, respectively. The AOT concentration, where the protective effect was observed, was too low to form its micelle-like aggregate. Then the protein structures might be stabilized by a cross-linking of surfactant monomers bound to specific sites. These specific sites might exist between a group of nonpolar residues and a positively charged residue located on several sets of amphiphilic helical rods in the proteins. Such a unique function of the double-tailed ionic surfactant is first presented by its characteristic nature as an amphiphilic material.

Mutual storage mode ion/ion reactions in a hybrid linear ion trap

Ion/ion proton transfer reactions involving mutual storage of both ion polarities in a linear ion trap (LIT) that comprises part of a hybrid triple quadrupole/linear ion trap mass spectrometer have been effected. Mutual ion storage in the x- and y-dimensions arises from the normal operation of the oscillating quadrupole field of the quadrupole array, while storage in the z-dimension is enabled by applying unbalanced radio-frequency amplitudes to opposing sets of rods of the array. Efficient trapping (>90%) is achieved for thermalized ions over periods of several seconds. Reactions were demonstrated for multiply charged protein/peptide cations formed by electrospray with anions derived from glow discharge ionization of perfluoro(methyldecalin) (PMD) introduced from the side of the LIT rod array. Doubly and singly charged protein ions are readily formed via ion/ion reactions. The parameters that affect ion/ion reactions are discussed, including the degree of RF unbalance on the LIT rods, vacuum pressure, nature of the buffer gas, reaction time, anion abundance, and the low mass cutoff for ion/ion reaction. The present system has a demonstrated upper mass-to-charge ratio limit of at least 33,000. The system also has high flexibility with respect to defining MS(n) experiments involving both collision-induced dissociation (CID) and ion/ion reactions. Experiments are demonstrated involving beam-type CID in the pressurized collision quadrupole (Q2) followed by ion/ion reactions involving the product ions in the LIT. Ion parking experiments are also demonstrated using the mutual storage ion/ion reaction mode in the LIT, with a parking efficiency over 60%.

The inertia tensor versus static moment and mass in perceiving length and heaviness of hand-wielded rods.

In 2 experiments, participants haptically estimated length and heaviness of handheld rods while wielding without seeing them. The sets of rods had been constructed such that variation of static moment and the 1st eigenvalue of the inertia tensor (I 1) were separated. Consistent with previous findings, perceived rod length correlated strongly with I1. However, multiple regressions on current data as well as data from previous studies showed a comparable strong correlation between perceived rod length and static moment plus mass. Contrary to previous findings, perceived heaviness correlated strongly with static moment and only weakly with the eigenvalues of the inertia tensor. These results suggest that the inertia tensor does not provide the sole foundation for a theory of dynamic touch. In the past decade or so, significant strides have been made in understanding the perception of properties of objects that are held in the hand but not seen. A large body of experimental data has been presented in support of the hypothesis that many instances of haptic perception are governed by a single yet multivalued physical entity, the inertia tensor ( I). This 3 3 tensor is symmetrical and thus contains six independent numbers. In diagonalized form—that is, when the tensor is expressed with respect to the unique set of axes of symmetrical mass distribution (the so-called principal axes of inertia)—the inertia tensor consists of three elements denoted as the principal moments of inertia or eigenvalues. These principal moments define an object’s (invariant) resistance against rotational acceleration around its principal axes of inertia and have been found to be related to perception of an object’s length (Solomon & Turvey, 1988; Solomon, Turvey, & Burton, 1989a, 1989b), width and height (Turvey, Burton, Amazeen, Butwill, & Carello, 1998), and heaviness (Amazeen & Turvey, 1996). In addition, the eigenvectors of the inertia tensor (defining the direction of the principal axes of inertia of the object) have been found to be related to the perception of an object’s orientation (Pagano & Turvey, 1998; Turvey, Burton, Pagano, Solomon, & Runeson, 1992). More recently, it has been suggested that perception of grip position is a function of the off-diagonal elements of the inertia tensor (i.e., the products of inertia; Pagano, KinsellaShaw, Cassidy, & Turvey, 1994) and that the perception of an object’s partial forward length (i.e., the distance from the hand to the forward-directed endpoint of the rod) is a function of both the moments and products of inertia (Carello, Santana, & Burton, 1996; Pagano, Carello, & Turvey, 1996). In the majority of the studies cited, the invariance of I as well as the fact that it provides information about both magnitude and direction, has been emphasized to support the inertia tensor hypothesis. However, when an object is held as still as possible, it appears difficult to perceive its properties through I because, by definition, an object’s resistance to rotation manifests itself only when the object is rotated. Under static conditions, physical properties such as the static moment (i.e., the first moment of mass

LIGHTING POSITION AND JUDGMENTS OF DISTANCE OF SHADOW-CASTING OBJECTS

Participants recruited on the web performed in two experiments in which they viewed eight pictures of the same two rods in the exact same positions with shadows generated by a light source located at eight positions around the rods. In Exp. 1, participants judged how much shadows projected to the front, back, and sides of the rods facilitated the correct perception of the actual distance of the rods relative to each other. In Exp. 1 (n: 52), frontal lighting facilitated judgments more than lighting from the rear, but frontal and side lighting did not differ in facultative effects. In Exp. 2 (n: 72), Judgments of rods depicted with shadows were relative to a judgment of the rods depicted without shadows (raw scores were the value of the judgment of the shadowless rods subtracted from the value of the judgment of each of the eight sets of rods). Again, frontal lighting was more facilitative than rear lighting and frontal lighting did not differ from side lighting. However, when the average of each participant's backlighting judgments was compared with his judgment of the shadowless rods, shadows generated by backlighting were more facilitative than none.

A non linear model for the PWR fuel assembly seismic analysis

In seismic PWR core analysis, the non linear behavior of fuel assemblies has to be studied taking into account variations of stiffness and damping due to the slippage of rods in spacer grids. Based on the linear CEA’s assembly model, principally composed of two beams representing sets of rods and thimbles, a linear model is described. In the second part of this paper the slippage and loss of contact of rods on a grid relic is analyzed. Based on the Coulomb friction model and plasticity analogy, a grid model constituted of elastoplastic hinge and non linear springs is proposed to simulate the progressive slippage of rods inside the cells. In the third part, a non linear assembly model is designed and validated with experimental data. This model represented with success the increase of damping and decay of frequency when the magnitude of the dynamic loading increases.

Shadows as sources of cues for distance of shadow-casting objects.

Shadows are neglected sources of information about shadow-casting objects' distance (location). In an experiment using real shadows, participants judged the distance of two rods, either with shadows (illumination from the left) or without shadows. Without shadows, a thin rod raised slightly above the surface was incorrectly judged to be more distant than a thick rod, but with shadows the thin rod was accurately judged to be closer. For judgments to be correct, shadows had to overwhelm competing height and stimulus-size cues. Exp. II involved nonoverlapping shadows produced by a light placed in front of the rods. Again, without shadows the thin-elevated rod was incorrectly judged to be more distant, but with shadows it was correctly judged to be closer. Exp. III involved two sets of thick and thin elevated rods and frontal lighting. Judgments were accurate when shadows were present but inaccurate when shadows were absent. Experiments conducted through the American Psychological Society Web-research site replicated results of Exp. I, II, and III. A final Web experiment replicated results of the others, but with shadows produced by illumination from the right. Three properties of shadows--angles, interposition, and positioning--are possible sources of distance information associated with cast shadows.

Photonic band gaps of two-dimensional photonic lattices: the face-centered graphite structures

We describe the calculation of photonic band structures of two-dimensional lattices made of more than one dielectric array. In particular, we study a face-centered graphite (fcg) structure obtained by an arrangement of two sets of cylindrical rods, one located at the vertices of regular hexagons (graphite sublattice) and another in the center of the hexagons (triangle sublattice). Changing the diameter of the centered rods, different patterns are produced including both triangle and graphite structures. We evaluate their relationships in terms of the existence of absolute photonic band gaps common to E and H polarized waves.