54. VAL COUNTERWEIGHT CAR DURING CONSTRUCTION SHOWING CAR FRAME, WHEEL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

54. VAL COUNTERWEIGHT CAR DURING CONSTRUCTION SHOWING CAR FRAME, WHEEL ASSEMBLIES AND METAL REINFORCING, December 19, 1947. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

22. VAL, VIEW OF PROJECTILE LOADING DECK LOOKING NORTHEAST TOWARD ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. VAL, VIEW OF PROJECTILE LOADING DECK LOOKING NORTHEAST TOWARD TOP OF CONCRETE 'A' FRAME STRUCTURE SHOWING DRIVE CABLES, DRIVE GEAR, BOTTOM OF CAMERA TOWER AND 'CROWS NEST' CONTROL ROOM. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

75. FIRST TEST SHOT OF THE VAL AT THE DEDICATION ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

75. FIRST TEST SHOT OF THE VAL AT THE DEDICATION CEREMONIES AS SEEN FROM A FIXED CAMERA STATION, May 7, 1948. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

83. DETAIL OF THE MUZZLE END OF THE LAUNCHER BRIDGE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

83. DETAIL OF THE MUZZLE END OF THE LAUNCHER BRIDGE ON TEMPORARY SUPPORTS LOOKING NORTHEAST SHOWING TWO LAUNCHING TUBES, Date unknown, circa 1950'S. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

82. DETAIL OF THE MUZZLE END OF THE LAUNCHER BRIDGE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

82. DETAIL OF THE MUZZLE END OF THE LAUNCHER BRIDGE LOOKING NORTH SHOWING THE CONNECTING BRIDGE AND TWO LAUNCHING TUBES, Date unknown, circa 1952. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

81. VIEW OF VAL LOOKING NORTH AS SEEN FROM THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

81. VIEW OF VAL LOOKING NORTH AS SEEN FROM THE RESERVOIR SHOWING TWO LAUNCHING TUBES ON THE LAUNCHER BRIDGE, Date unknown, circa 1952. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

63. VIEW LOOKING DOWN VAL LAUNCHING SLAB SHOWING DRIVE GEARS, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

63. VIEW LOOKING DOWN VAL LAUNCHING SLAB SHOWING DRIVE GEARS, CABLES, LAUNCHER RAILS, PROJECTILE CAR AND SUPPORT CARRIAGE, April 8, 1948. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

57. INTERIOR VIEW OF VAL BRIDGE STRUCTURE SHOWING LAUNCHING TUBE, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

57. INTERIOR VIEW OF VAL BRIDGE STRUCTURE SHOWING LAUNCHING TUBE, STAIRS AND PORTION OF LAUNCHING DECK. NOTE SUPPORT CARRIAGE ASSEMBLY IN DISTANCE. Date unknown, circa March 1948. (Original photograph in possession of Dave Willis, San Diego, California.) - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

78. PHOTO OF A PROJECTILE FIRING USING A SABOT TAKEN ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

78. PHOTO OF A PROJECTILE FIRING USING A SABOT TAKEN WITH A 70 MM MITCHEL MOTION PICTURE CAMERA, Date unknown, circa 1950. (Original photograph in possession of Dave Willis, San Diego, California.) Photograph represents central frame of negative. - Variable Angle Launcher Complex, Variable Angle Launcher, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

Anterior Inferior Cerebellar Arteries Juxtaposed with the Internal Acoustic Meatus and Their Relationship to the Cranial Nerve VII/VIII Complex

PubMed Central

Alonso, Fernando; Iwanaga, Joe; Oskouian, Rod J; Loukas, Marios; Demerdash, Amin; Tubbs, R. Shane

2017-01-01

Vascular loops in the cerebellopontine angle (CPA) and their relationship to cranial nerves have been used to explain neurological symptoms. The anterior inferior cerebellar artery (AICA) has variable branches producing vascular loops that can compress the facial cranial nerve (CN) VII and vestibulocochlear (CN VIII) nerves. AICA compression of the facial-vestibulocochlear nerve complex can lead to various clinical presentations, including hemifacial spasm (HFS), tinnitus, and hemiataxia. The formation of arterial loops inside or outside of the internal auditory meatus (IAM) can cause abutment or compression of CN VII and CN VIII. Twenty-five (50 sides) fresh adult cadavers underwent dissection of the cerebellopontine angle in the supine position. In regard to relationships between the AICA and the nerves of the facial/vestibulocochlear complex, 33 arteries (66%) traveled in a plane between the facial/nervus intermedius nerves and the cochlear and vestibular nerves. Five arteries (10%) traveled below the CN VII/VIII complex, six (12%) traveled posterior to the nerve complex, four (8%) formed a semi-circle around the upper half of the nerve complex, and two (4%) traveled between and partially separated the nervus intermedius and facial nerve proper. Our study found that the majority of AICA will travel in a plane between the facial/nervus intermedius nerves and the cochlear and vestibular nerves. Although the relationship between the AICA and porus acusticus and AICA and the nerves of the CN VII/VIII complex are variable, based on our findings, some themes exist. Surgeons should consider these with approaches to the cerebellopontine angle. PMID:29057182

Anterior Inferior Cerebellar Arteries Juxtaposed with the Internal Acoustic Meatus and Their Relationship to the Cranial Nerve VII/VIII Complex.

PubMed

Alonso, Fernando; Kassem, Mohammad W; Iwanaga, Joe; Oskouian, Rod J; Loukas, Marios; Demerdash, Amin; Tubbs, R Shane

2017-08-16

Vascular loops in the cerebellopontine angle (CPA) and their relationship to cranial nerves have been used to explain neurological symptoms. The anterior inferior cerebellar artery (AICA) has variable branches producing vascular loops that can compress the facial cranial nerve (CN) VII and vestibulocochlear (CN VIII) nerves. AICA compression of the facial-vestibulocochlear nerve complex can lead to various clinical presentations, including hemifacial spasm (HFS), tinnitus, and hemiataxia. The formation of arterial loops inside or outside of the internal auditory meatus (IAM) can cause abutment or compression of CN VII and CN VIII. Twenty-five (50 sides) fresh adult cadavers underwent dissection of the cerebellopontine angle in the supine position. In regard to relationships between the AICA and the nerves of the facial/vestibulocochlear complex, 33 arteries (66%) traveled in a plane between the facial/nervus intermedius nerves and the cochlear and vestibular nerves. Five arteries (10%) traveled below the CN VII/VIII complex, six (12%) traveled posterior to the nerve complex, four (8%) formed a semi-circle around the upper half of the nerve complex, and two (4%) traveled between and partially separated the nervus intermedius and facial nerve proper. Our study found that the majority of AICA will travel in a plane between the facial/nervus intermedius nerves and the cochlear and vestibular nerves. Although the relationship between the AICA and porus acusticus and AICA and the nerves of the CN VII/VIII complex are variable, based on our findings, some themes exist. Surgeons should consider these with approaches to the cerebellopontine angle.

Predicting wettability behavior of fluorosilica coated metal surface using optimum neural network

NASA Astrophysics Data System (ADS)

Taghipour-Gorjikolaie, Mehran; Valipour Motlagh, Naser

2018-02-01

The interaction between variables, which are effective on the surface wettability, is very complex to predict the contact angles and sliding angles of liquid drops. In this paper, in order to solve this complexity, artificial neural network was used to develop reliable models for predicting the angles of liquid drops. Experimental data are divided into training data and testing data. By using training data and feed forward structure for the neural network and using particle swarm optimization for training the neural network based models, the optimum models were developed. The obtained results showed that regression index for the proposed models for the contact angles and sliding angles are 0.9874 and 0.9920, respectively. As it can be seen, these values are close to unit and it means the reliable performance of the models. Also, it can be inferred from the results that the proposed model have more reliable performance than multi-layer perceptron and radial basis function based models.

7. VAL CAMERA CAR, DETAIL OF 'FLARE' OR TRAJECTORY CAMERA ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. VAL CAMERA CAR, DETAIL OF 'FLARE' OR TRAJECTORY CAMERA INSIDE CAMERA CAR. - Variable Angle Launcher Complex, Camera Car & Track, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

7. VAL CAMERA STATION, INTERIOR VIEW OF CAMERA MOUNT, COMMUNICATION ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. VAL CAMERA STATION, INTERIOR VIEW OF CAMERA MOUNT, COMMUNICATION EQUIPMENT AND STORAGE CABINET. - Variable Angle Launcher Complex, Camera Stations, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

3. VAL CONTROL STATION, VIEW OF CONTROL PANELS SHOWING MAIN ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. VAL CONTROL STATION, VIEW OF CONTROL PANELS SHOWING MAIN PRESSURE GAUGES, LOOKING NORTH. - Variable Angle Launcher Complex, Control Station, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

8. VAL CAMERA CAR, CLOSEUP VIEW OF 'FLARE' OR TRAJECTORY ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. VAL CAMERA CAR, CLOSE-UP VIEW OF 'FLARE' OR TRAJECTORY CAMERA ON SLIDING MOUNT. - Variable Angle Launcher Complex, Camera Car & Track, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

6. VAL CAMERA CAR, DETAIL OF COMMUNICATION EQUIPMENT INSIDE CAMERA ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. VAL CAMERA CAR, DETAIL OF COMMUNICATION EQUIPMENT INSIDE CAMERA CAR WITH CAMERA MOUNT IN FOREGROUND. - Variable Angle Launcher Complex, Camera Car & Track, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

2. VAL CONTROL STATION, VIEW OF INTERIOR SHOWING EXTERIOR DOOR, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VAL CONTROL STATION, VIEW OF INTERIOR SHOWING EXTERIOR DOOR, WINDOWS AND CONTROL PANELS, LOOKING SOUTHEAST. - Variable Angle Launcher Complex, Control Station, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

Graphic tracings of condylar paths and measurements of condylar angles.

PubMed

el-Gheriani, A S; Winstanley, R B

1989-01-01

A study was carried out to determine the accuracy of different methods of measuring condylar inclination from graphical recordings of condylar paths. Thirty subjects made protrusive mandibular movements while condylar inclination was recorded on a graph paper card. A mandibular facebow and intraoral central bearing plate facilitated the procedure. The first method proved to be too variable to be of value in measuring condylar angles. The spline curve fitting technique was shown to be accurate, but its use clinically may prove complex. The mathematical method was more practical and overcame the variability of the tangent method. Other conclusions regarding condylar inclination are outlined.

Edge delamination in angle-ply composite laminates, part 5

NASA Technical Reports Server (NTRS)

Wang, S. S.

1981-01-01

A theoretical method was developed for describing the edge delamination stress intensity characteristics in angle-ply composite laminates. The method is based on the theory of anisotropic elasticity. The edge delamination problem is formulated using Lekhnitskii's complex-variable stress potentials and an especially developed eigenfunction expansion method. The method predicts exact orders of the three-dimensional stress singularity in a delamination crack tip region. With the aid of boundary collocation, the method predicts the complete stress and displacement fields in a finite-dimensional, delaminated composite. Fracture mechanics parameters such as the mixed-mode stress intensity factors and associated energy release rates for edge delamination can be calculated explicity. Solutions are obtained for edge delaminated (theta/-theta theta/-theta) angle-ply composites under uniform axial extension. Effects of delamination lengths, fiber orientations, lamination and geometric variables are studied.

Optimization of parameter values for complex pulse sequences by simulated annealing: application to 3D MP-RAGE imaging of the brain.

PubMed

Epstein, F H; Mugler, J P; Brookeman, J R

1994-02-01

A number of pulse sequence techniques, including magnetization-prepared gradient echo (MP-GRE), segmented GRE, and hybrid RARE, employ a relatively large number of variable pulse sequence parameters and acquire the image data during a transient signal evolution. These sequences have recently been proposed and/or used for clinical applications in the brain, spine, liver, and coronary arteries. Thus, the need for a method of deriving optimal pulse sequence parameter values for this class of sequences now exists. Due to the complexity of these sequences, conventional optimization approaches, such as applying differential calculus to signal difference equations, are inadequate. We have developed a general framework for adapting the simulated annealing algorithm to pulse sequence parameter value optimization, and applied this framework to the specific case of optimizing the white matter-gray matter signal difference for a T1-weighted variable flip angle 3D MP-RAGE sequence. Using our algorithm, the values of 35 sequence parameters, including the magnetization-preparation RF pulse flip angle and delay time, 32 flip angles in the variable flip angle gradient-echo acquisition sequence, and the magnetization recovery time, were derived. Optimized 3D MP-RAGE achieved up to a 130% increase in white matter-gray matter signal difference compared with optimized 3D RF-spoiled FLASH with the same total acquisition time. The simulated annealing approach was effective at deriving optimal parameter values for a specific 3D MP-RAGE imaging objective, and may be useful for other imaging objectives and sequences in this general class.

5. VAL CAMERA CAR, DETAIL OF HOIST AT SIDE OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. VAL CAMERA CAR, DETAIL OF HOIST AT SIDE OF BRIDGE AND ENGINE CAR ON TRACKS, LOOKING NORTHEAST. - Variable Angle Launcher Complex, Camera Car & Track, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

3. VAL CAMERA CAR, VIEW OF CAMERA CAR AND TRACK ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. VAL CAMERA CAR, VIEW OF CAMERA CAR AND TRACK WITH THE VAL TO THE RIGHT, LOOKING NORTHEAST. - Variable Angle Launcher Complex, Camera Car & Track, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

2. VAL CAMERA CAR, VIEW OF CAMERA CAR AND TRACK ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VAL CAMERA CAR, VIEW OF CAMERA CAR AND TRACK WITH CAMERA STATION ABOVE LOOKING WEST TAKEN FROM RESERVOIR. - Variable Angle Launcher Complex, Camera Car & Track, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

3D sorghum reconstructions from depth images identify QTL regulating shoot architecture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mccormick, Ryan F.; Truong, Sandra K.; Mullet, John E.

Dissecting the genetic basis of complex traits is aided by frequent and nondestructive measurements. Advances in range imaging technologies enable the rapid acquisition of three-dimensional (3D) data from an imaged scene. A depth camera was used to acquire images of sorghum (Sorghum bicolor), an important grain, forage, and bioenergy crop, at multiple developmental time points from a greenhouse-grown recombinant inbred line population. A semiautomated software pipeline was developed and used to generate segmented, 3D plant reconstructions from the images. Automated measurements made from 3D plant reconstructions identified quantitative trait loci for standard measures of shoot architecture, such as shoot height,more » leaf angle, and leaf length, and for novel composite traits, such as shoot compactness. The phenotypic variability associated with some of the quantitative trait loci displayed differences in temporal prevalence; for example, alleles closely linked with the sorghum Dwarf3 gene, an auxin transporter and pleiotropic regulator of both leaf inclination angle and shoot height, influence leaf angle prior to an effect on shoot height. Furthermore, variability in composite phenotypes that measure overall shoot architecture, such as shoot compactness, is regulated by loci underlying component phenotypes like leaf angle. As such, depth imaging is an economical and rapid method to acquire shoot architecture phenotypes in agriculturally important plants like sorghum to study the genetic basis of complex traits.« less

3D sorghum reconstructions from depth images identify QTL regulating shoot architecture

DOE PAGES

Mccormick, Ryan F.; Truong, Sandra K.; Mullet, John E.

2016-08-15

Dissecting the genetic basis of complex traits is aided by frequent and nondestructive measurements. Advances in range imaging technologies enable the rapid acquisition of three-dimensional (3D) data from an imaged scene. A depth camera was used to acquire images of sorghum (Sorghum bicolor), an important grain, forage, and bioenergy crop, at multiple developmental time points from a greenhouse-grown recombinant inbred line population. A semiautomated software pipeline was developed and used to generate segmented, 3D plant reconstructions from the images. Automated measurements made from 3D plant reconstructions identified quantitative trait loci for standard measures of shoot architecture, such as shoot height,more » leaf angle, and leaf length, and for novel composite traits, such as shoot compactness. The phenotypic variability associated with some of the quantitative trait loci displayed differences in temporal prevalence; for example, alleles closely linked with the sorghum Dwarf3 gene, an auxin transporter and pleiotropic regulator of both leaf inclination angle and shoot height, influence leaf angle prior to an effect on shoot height. Furthermore, variability in composite phenotypes that measure overall shoot architecture, such as shoot compactness, is regulated by loci underlying component phenotypes like leaf angle. As such, depth imaging is an economical and rapid method to acquire shoot architecture phenotypes in agriculturally important plants like sorghum to study the genetic basis of complex traits.« less

Experimental evidence of exciton-plasmon coupling in densely packed dye doped core-shell nanoparticles obtained via microfluidic technique

NASA Astrophysics Data System (ADS)

De Luca, A.; Iazzolino, A.; Salmon, J.-B.; Leng, J.; Ravaine, S.; Grigorenko, A. N.; Strangi, G.

2014-09-01

The interplay between plasmons and excitons in bulk metamaterials are investigated by performing spectroscopic studies, including variable angle pump-probe ellipsometry. Gain functionalized gold nanoparticles have been densely packed through a microfluidic chip, representing a scalable process towards bulk metamaterials based on self-assembly approach. Chromophores placed at the hearth of plasmonic subunits ensure exciton-plasmon coupling to convey excitation energy to the quasi-static electric field of the plasmon states. The overall complex polarizability of the system, probed by variable angle spectroscopic ellipsometry, shows a significant modification under optical excitation, as demonstrated by the behavior of the ellipsometric angles Ψ and Δ as a function of suitable excitation fields. The plasmon resonances observed in densely packed gain functionalized core-shell gold nanoparticles represent a promising step to enable a wide range of electromagnetic properties and fascinating applications of plasmonic bulk systems for advanced optical materials.

Variation of M···H-C Interactions in Square-Planar Complexes of Nickel(II), Palladium(II), and Platinum(II) Probed by Luminescence Spectroscopy and X-ray Diffraction at Variable Pressure.

PubMed

Poirier, Stéphanie; Lynn, Hudson; Reber, Christian; Tailleur, Elodie; Marchivie, Mathieu; Guionneau, Philippe; Probert, Michael R

2018-06-12

Luminescence spectra of isoelectronic square-planar d 8 complexes with 3d, 4d, and 5d metal centers show d-d luminescence with an energetic order different from that of the spectrochemical series, indicating that additional structural effects, such as different ligand-metal-ligand angles, are important factors. Variable-pressure luminescence spectra of square-planar nickel(II), palladium(II), and platinum(II) complexes with dimethyldithiocarbamate ({CH 3 } 2 DTC) ligands and their deuterated analogues show unexpected variations of the shifts of their maxima. High-resolution crystal structures and crystal structures at variable pressure for [Pt{(CH 3 ) 2 DTC} 2 ] indicate that intermolecular M···H-C interactions are at the origin of these different shifts.

[Therapeutic algorithm of idiopathic scoliosis in children].

PubMed

Ciortan, Ionica; Goţia, D G

2008-01-01

Acquired deformations of spinal cord (scoliosis, kyphosis, lordosis) represent a frequent pathology in child; their treatment is complex, with variable results which depend on various parameters. Mild scoliosis, with an angle less than 30 degrees, is treated with physiotherapy and regular follow-up. If the angle is higher than 30 degrees, the orthopedic corset is required; the angle over 45 degrees impose surgically correction. The indications of every therapeutic method depend on many factors, the main target of the treatment is to prevent the aggravation of the curvature; concerning the surgery, the goal is to obtain a correction as normal as possible of the spinal axis.

Dihedral angle principal component analysis of molecular dynamics simulations.

PubMed

Altis, Alexandros; Nguyen, Phuong H; Hegger, Rainer; Stock, Gerhard

2007-06-28

It has recently been suggested by Mu et al. [Proteins 58, 45 (2005)] to use backbone dihedral angles instead of Cartesian coordinates in a principal component analysis of molecular dynamics simulations. Dihedral angles may be advantageous because internal coordinates naturally provide a correct separation of internal and overall motion, which was found to be essential for the construction and interpretation of the free energy landscape of a biomolecule undergoing large structural rearrangements. To account for the circular statistics of angular variables, a transformation from the space of dihedral angles {phi(n)} to the metric coordinate space {x(n)=cos phi(n),y(n)=sin phi(n)} was employed. To study the validity and the applicability of the approach, in this work the theoretical foundations underlying the dihedral angle principal component analysis (dPCA) are discussed. It is shown that the dPCA amounts to a one-to-one representation of the original angle distribution and that its principal components can readily be characterized by the corresponding conformational changes of the peptide. Furthermore, a complex version of the dPCA is introduced, in which N angular variables naturally lead to N eigenvalues and eigenvectors. Applying the methodology to the construction of the free energy landscape of decaalanine from a 300 ns molecular dynamics simulation, a critical comparison of the various methods is given.

Dihedral angle principal component analysis of molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Altis, Alexandros; Nguyen, Phuong H.; Hegger, Rainer; Stock, Gerhard

2007-06-01

It has recently been suggested by Mu et al. [Proteins 58, 45 (2005)] to use backbone dihedral angles instead of Cartesian coordinates in a principal component analysis of molecular dynamics simulations. Dihedral angles may be advantageous because internal coordinates naturally provide a correct separation of internal and overall motion, which was found to be essential for the construction and interpretation of the free energy landscape of a biomolecule undergoing large structural rearrangements. To account for the circular statistics of angular variables, a transformation from the space of dihedral angles {φn} to the metric coordinate space {xn=cosφn,yn=sinφn} was employed. To study the validity and the applicability of the approach, in this work the theoretical foundations underlying the dihedral angle principal component analysis (dPCA) are discussed. It is shown that the dPCA amounts to a one-to-one representation of the original angle distribution and that its principal components can readily be characterized by the corresponding conformational changes of the peptide. Furthermore, a complex version of the dPCA is introduced, in which N angular variables naturally lead to N eigenvalues and eigenvectors. Applying the methodology to the construction of the free energy landscape of decaalanine from a 300ns molecular dynamics simulation, a critical comparison of the various methods is given.

9. COMPLETED ROLLING CAMERA CAR ON RAILROAD TRACK AND BRIDGE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. COMPLETED ROLLING CAMERA CAR ON RAILROAD TRACK AND BRIDGE LOOKING WEST, APRIL 26, 1948. (ORIGINAL PHOTOGRAPH IN POSSESSION OF DAVE WILLIS, SAN DIEGO, CALIFORNIA.) - Variable Angle Launcher Complex, Camera Car & Track, CA State Highway 39 at Morris Reservior, Azusa, Los Angeles County, CA

Optimization of an angle-beam ultrasonic approach for characterization of impact damage in composites

NASA Astrophysics Data System (ADS)

Henry, Christine; Kramb, Victoria; Welter, John T.; Wertz, John N.; Lindgren, Eric A.; Aldrin, John C.; Zainey, David

2018-04-01

Advances in NDE method development are greatly improved through model-guided experimentation. In the case of ultrasonic inspections, models which provide insight into complex mode conversion processes and sound propagation paths are essential for understanding the experimental data and inverting the experimental data into relevant information. However, models must also be verified using experimental data obtained under well-documented and understood conditions. Ideally, researchers would utilize the model simulations and experimental approach to efficiently converge on the optimal solution. However, variability in experimental parameters introduce extraneous signals that are difficult to differentiate from the anticipated response. This paper discusses the results of an ultrasonic experiment designed to evaluate the effect of controllable variables on the anticipated signal, and the effect of unaccounted for experimental variables on the uncertainty in those results. Controlled experimental parameters include the transducer frequency, incidence beam angle and focal depth.

Amplitude and dynamics of polarization-plane signaling in the central complex of the locust brain

PubMed Central

Bockhorst, Tobias

2015-01-01

The polarization pattern of skylight provides a compass cue that various insect species use for allocentric orientation. In the desert locust, Schistocerca gregaria, a network of neurons tuned to the electric field vector (E-vector) angle of polarized light is present in the central complex of the brain. Preferred E-vector angles vary along slices of neuropils in a compasslike fashion (polarotopy). We studied how the activity in this polarotopic population is modulated in ways suited to control compass-guided locomotion. To this end, we analyzed tuning profiles using measures of correlation between spike rate and E-vector angle and, furthermore, tested for adaptation to stationary angles. The results suggest that the polarotopy is stabilized by antagonistic integration across neurons with opponent tuning. Downstream to the input stage of the network, responses to stationary E-vector angles adapted quickly, which may correlate with a tendency to steer a steady course previously observed in tethered flying locusts. By contrast, rotating E-vectors corresponding to changes in heading direction under a natural sky elicited nonadapting responses. However, response amplitudes were particularly variable at the output stage, covarying with the level of ongoing activity. Moreover, the responses to rotating E-vector angles depended on the direction of rotation in an anticipatory manner. Our observations support a view of the central complex as a substrate of higher-stage processing that could assign contextual meaning to sensory input for motor control in goal-driven behaviors. Parallels to higher-stage processing of sensory information in vertebrates are discussed. PMID:25609107

The effect of workstation and task variables on forces applied during simulated meat cutting.

PubMed

McGorry, Raymond W; Dempsey, Patrick G; O'Brien, Niall V

2004-12-01

The purpose of the study was to investigate factors related to force and postural exposure during a simulated meat cutting task. The hypothesis was that workstation, tool and task variables would affect the dependent kinetic variables of gripping force, cutting moment and the dependent kinematic variables of elbow elevation and wrist angular displacement in the flexion/extension and radial/ulnar deviation planes. To evaluate this hypothesis a 3 x 3 x 2 x 2 x 2 (surface orientation by surface height by blade angle by cut complexity by work pace) within-subject factorial design was conducted with 12 participants. The results indicated that the variables can act and interact to modify the kinematics and kinetics of a cutting task. Participants used greater grip force and cutting moment when working at a pace based on productivity. The interactions of the work surface height and orientation indicated that the use of an adjustable workstation could minimize wrist deviation from neutral and improve shoulder posture during cutting operations. Angling the knife blade also interacted with workstation variables to improve wrist and upper extremity posture, but this benefit must be weighed against the potential for small increases in force exposure.

Reconstructing the equilibrium Boltzmann distribution from well-tempered metadynamics.

PubMed

Bonomi, M; Barducci, A; Parrinello, M

2009-08-01

Metadynamics is a widely used and successful method for reconstructing the free-energy surface of complex systems as a function of a small number of suitably chosen collective variables. This is achieved by biasing the dynamics of the system. The bias acting on the collective variables distorts the probability distribution of the other variables. Here we present a simple reweighting algorithm for recovering the unbiased probability distribution of any variable from a well-tempered metadynamics simulation. We show the efficiency of the reweighting procedure by reconstructing the distribution of the four backbone dihedral angles of alanine dipeptide from two and even one dimensional metadynamics simulation. 2009 Wiley Periodicals, Inc.

[Comparative study on the strength of different mechanisms of operation of multidirectionally angle-stable distal radius plates].

PubMed

Rausch, S; Hoffmeier, K; Gueorguiev, B G; Klos, K; Gras, F; Hofmann, G O; Mückley, T

2011-12-01

Polyaxial angle-stable plating is thought to be particularly beneficial in the management of complex intra-articular fractures of the distal radius. The present study was performed to investigate the strength of polyaxial locking interfaces of distal radius plates. We tested the polyaxial interfaces of 3 different distal radius plates (2.4 mm Variable Angle LCP Two-Column Volar Distal Radius Plate, Synthes, Palmar Classic, Königsee Implantate and VariAx Plate Stryker). The strength of 0° and 10° screw locking angle was obtained during static loading. The strength of Palmar Classic with a 0° locking angle is significantly the best of all tested systems. With a 10° locking angle there is no significant difference between Palmar Classic, Two column Plate and VariAx Plate. The strength of polyaxial interfaces differs between the tested systems. A reduction of ultimate strength is due to increases of screw locking angle. The design of polyaxial locking interfaces should be investigated in human bone models. © Georg Thieme Verlag KG Stuttgart · New York.

Angular position of the cleat according to torsional parameters of the cyclist's lower limb.

PubMed

Ramos-Ortega, Javier; Domínguez, Gabriel; Castillo, José Manuel; Fernández-Seguín, Lourdes; Munuera, Pedro V

2014-05-01

The aim of this work was to study the relationship of torsional and rotational parameters of the lower limb with a specific angular position of the cleat to establish whether these variables affect the adjustment of the cleat. Correlational study. Motion analysis laboratory. Thirty-seven male cyclists of high performance. The variables studied of the cyclist's lower limb were hip rotation (internal and external), tibial torsion angle, Q angle, and forefoot adductus angle. The cleat angle was measured through a photograph of the sole and with an Rx of this using the software AutoCAD 2008. The variables were photograph angle (photograph), the variable denominated cleat-tarsus minor angle, and a variable denominated cleat-second metatarsal angle (Rx). Analysis included the intraclass correlation coefficient for the reliability of the measurements, Student's t test performed on the dependent variables to compare side, and the multiple linear regression models were calculated using the software SPSS 15.0 for Windows. The Student's t test performed on the dependent variables to compare side showed no significant differences (P = 0.209 for the photograph angle, P = 0.735 for the cleat-tarsus minor angle, and P = 0.801 for the cleat-second metatarsal angle). Values of R and R2 for the photograph angle model were 0.303 and 0.092 (P = 0.08), the cleat/tarsus minor angle model were 0.683 and 0.466 (P < 0.001), and the cleat/second metatarsal angle model were 0.618 and 0.382, respectively (P < 0.001). The equation given by the model was cleat-tarsus minor angle = 75.094 - (0.521 × forefoot adductus angle) + (0.116 × outward rotation of the hips) + (0.220 × Q angle).

Geometric approach to the design of an imaging probe to evaluate the iridocorneal angle structures

NASA Astrophysics Data System (ADS)

Hong, Xun Jie Jeesmond; V. K., Shinoj; Murukeshan, V. M.; Baskaran, M.; Aung, Tin

2017-06-01

Photographic imaging methods allow the tracking of anatomical changes in the iridocorneal angle structures and the monitoring of treatment responses overtime. In this work, we aim to design an imaging probe to evaluate the iridocorneal angle structures using geometrical optics. We first perform an analytical analysis on light propagation from the anterior chamber of the eye to the exterior medium using Snell's law. This is followed by adopting a strategy to achieve uniform near field irradiance, by simplifying the complex non-rotational symmetric irradiance distribution of LEDs tilted at an angle. The optimization is based on the geometric design considerations of an angled circular ring array of 4 LEDs (or a 2 × 2 square LED array). The design equation give insights on variable parameters such as the illumination angle of the LEDs, ring array radius, viewing angle of the LEDs, and the working distance. A micro color CCD video camera that has sufficient resolution to resolve the iridocorneal angle structures at the required working distance is then chosen. The proposed design aspects fulfil the safety requirements recommended by the International Commission on Non-ionizing Radiation Protection.

Refining Collective Coordinates and Improving Free Energy Representation in Variational Enhanced Sampling.

PubMed

Yang, Yi Isaac; Parrinello, Michele

2018-06-12

Collective variables are used often in many enhanced sampling methods, and their choice is a crucial factor in determining sampling efficiency. However, at times, searching for good collective variables can be challenging. In a recent paper, we combined time-lagged independent component analysis with well-tempered metadynamics in order to obtain improved collective variables from metadynamics runs that use lower quality collective variables [ McCarty, J.; Parrinello, M. J. Chem. Phys. 2017 , 147 , 204109 ]. In this work, we extend these ideas to variationally enhanced sampling. This leads to an efficient scheme that is able to make use of the many advantages of the variational scheme. We apply the method to alanine-3 in water. From an alanine-3 variationally enhanced sampling trajectory in which all the six dihedral angles are biased, we extract much better collective variables able to describe in exquisite detail the protein complex free energy surface in a low dimensional representation. The success of this investigation is helped by a more accurate way of calculating the correlation functions needed in the time-lagged independent component analysis and from the introduction of a new basis set to describe the dihedral angles arrangement.

Shuttle Debris Impact Tool Assessment Using the Modern Design of Experiments

NASA Technical Reports Server (NTRS)

DeLoach, R.; Rayos, E. M.; Campbell, C. H.; Rickman, S. L.

2006-01-01

Computational tools have been developed to estimate thermal and mechanical reentry loads experienced by the Space Shuttle Orbiter as the result of cavities in the Thermal Protection System (TPS). Such cavities can be caused by impact from ice or insulating foam debris shed from the External Tank (ET) on liftoff. The reentry loads depend on cavity geometry and certain Shuttle state variables, among other factors. Certain simplifying assumptions have been made in the tool development about the cavity geometry variables. For example, the cavities are all modeled as shoeboxes , with rectangular cross-sections and planar walls. So an actual cavity is typically approximated with an idealized cavity described in terms of its length, width, and depth, as well as its entry angle, exit angle, and side angles (assumed to be the same for both sides). As part of a comprehensive assessment of the uncertainty in reentry loads estimated by the debris impact assessment tools, an effort has been initiated to quantify the component of the uncertainty that is due to imperfect geometry specifications for the debris impact cavities. The approach is to compute predicted loads for a set of geometry factor combinations sufficient to develop polynomial approximations to the complex, nonparametric underlying computational models. Such polynomial models are continuous and feature estimable, continuous derivatives, conditions that facilitate the propagation of independent variable errors. As an additional benefit, once the polynomial models have been developed, they require fewer computational resources to execute than the underlying finite element and computational fluid dynamics codes, and can generate reentry loads estimates in significantly less time. This provides a practical screening capability, in which a large number of debris impact cavities can be quickly classified either as harmless, or subject to additional analysis with the more comprehensive underlying computational tools. The polynomial models also provide useful insights into the sensitivity of reentry loads to various cavity geometry variables, and reveal complex interactions among those variables that indicate how the sensitivity of one variable depends on the level of one or more other variables. For example, the effect of cavity length on certain reentry loads depends on the depth of the cavity. Such interactions are clearly displayed in the polynomial response models.

On the complexity of classical guitar playing: functional adaptations to task constraints.

PubMed

Heijink, Hank; Meulenbroek, Ruud G J

2002-12-01

The authors performed a behavioral study of the complexity of left-hand finger movements in classical guitar playing. Six professional guitarists played movement sequences in a fixed tempo. Left-hand finger movements were recorded in 3 dimensions, and the guitar sound was recorded synchronously. Assuming that performers prefer to avoid extreme joint angles when moving, the authors hypothesized 3 complexity factors. The results showed differential effects of the complexity factors on the performance measures and on participants' judgments of complexity. The results demonstrated that keeping the joints in the middle of their range is an important principle in guitar playing, and players exploit the available tolerance in timing and placement of the left-hand fingers to control the acoustic output variability.

Analysis of fluid flow and solute transport through a single fracture with variable apertures intersecting a canister: Comparison between fractal and Gaussian fractures

NASA Astrophysics Data System (ADS)

Liu, L.; Neretnieks, I.

Canisters with spent nuclear fuel will be deposited in fractured crystalline rock in the Swedish concept for a final repository. The fractures intersect the canister holes at different angles and they have variable apertures and therefore locally varying flowrates. Our previous model with fractures with a constant aperture and a 90° intersection angle is now extended to arbitrary intersection angles and stochastically variable apertures. It is shown that the previous basic model can be simply amended to account for these effects. More importantly, it has been found that the distributions of the volumetric and the equivalent flow rates are all close to the Normal for both fractal and Gaussian fractures, with the mean of the distribution of the volumetric flow rate being determined solely by the hydraulic aperture, and that of the equivalent flow rate being determined by the mechanical aperture. Moreover, the standard deviation of the volumetric flow rates of the many realizations increases with increasing roughness and spatial correlation length of the aperture field, and so does that of the equivalent flow rates. Thus, two simple statistical relations can be developed to describe the stochastic properties of fluid flow and solute transport through a single fracture with spatially variable apertures. This obviates, then, the need to simulate each fracture that intersects a canister in great detail, and allows the use of complex fractures also in very large fracture network models used in performance assessment.

Comparison between medial rectus pulley fixation and augmented recession in children with convergence excess and variable-angle infantile esotropia.

PubMed

Fouad, Heba M; Abdelhakim, Mohamad A; Awadein, Ahmed; Elhilali, Hala

2016-10-01

To compare the outcomes of medial rectus (MR) muscle pulley fixation and augmented recession in children with convergence excess esotropia and variable-angle infantile esotropia. This was a prospective randomized interventional study in which children with convergence excess esotropia or variable-angle infantile esotropia were randomly allocated to either augmented MR muscle recession (augmented group) or MR muscle pulley posterior fixation (pulley group). In convergence excess, the MR recession was based on the average of distance and near angles of deviation with distance correction in the augmented group, and on the distance angle of deviation in the pulley group. In variable-angle infantile esotropia, the MR recession was based on the average of the largest and smallest angles in the augmented group and on the smallest angle in the pulley group. Pre- and postoperative ductions, versions, pattern strabismus, smallest and largest angles of deviation, and angle disparity were analyzed. Surgery was performed on 60 patients: 30 underwent bilateral augmented MR recession, and 30 underwent bilateral MR recession with pulley fixation. The success rate was statistically significantly higher (P = 0.037) in the pulley group (70%) than in the augmented group (40%). The postoperative smallest and largest angles and the angle disparity were statistically significantly lower in the pulley group than the augmented group (P < 0.01). Medial rectus muscle pulley fixation is a useful surgical step for addressing marked variability of the angle in variable angle esotropia and convergence excess esotropia. Copyright © 2016 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.

Development of reaching during mid-childhood from a Developmental Systems perspective.

PubMed

Golenia, Laura; Schoemaker, Marina M; Otten, Egbert; Mouton, Leonora J; Bongers, Raoul M

2018-01-01

Inspired by the Developmental Systems perspective, we studied the development of reaching during mid-childhood (5-10 years of age) not just at the performance level (i.e., endpoint movements), as commonly done in earlier studies, but also at the joint angle level. Because the endpoint position (i.e., the tip of the index finger) at the reaching target can be achieved with multiple joint angle combinations, we partitioned variability in joint angles over trials into variability that does not (goal-equivalent variability, GEV) and that does (non-goal-equivalent variability, NGEV) influence the endpoint position, using the Uncontrolled Manifold method. Quantifying this structure in joint angle variability allowed us to examine whether and how spatial variability of the endpoint at the reaching target is related to variability in joint angles and how this changes over development. 6-, 8- and 10-year-old children and young adults performed reaching movements to a target with the index finger. Polynomial trend analysis revealed a linear and a quadratic decreasing trend for the variable error. Linear decreasing and cubic trends were found for joint angle standard deviations at movement end. GEV and NGEV decreased gradually with age, but interestingly, the decrease of GEV was steeper than the decrease of NGEV, showing that the different parts of the joint angle variability changed differently over age. We interpreted these changes in the structure of variability as indicating changes over age in exploration for synergies (a family of task solutions), a concept that links the performance level with the joint angle level. Our results suggest changes in the search for synergies during mid-childhood development.

Variable-angle epifluorescence microscopy characterizes protein dynamics in the vicinity of plasma membrane in plant cells.

PubMed

Chen, Tong; Ji, Dongchao; Tian, Shiping

2018-03-14

The assembly of protein complexes and compositional lipid patterning act together to endow cells with the plasticity required to maintain compositional heterogeneity with respect to individual proteins. Hence, the applications for imaging protein localization and dynamics require high accuracy, particularly at high spatio-temporal level. We provided experimental data for the applications of Variable-Angle Epifluorescence Microscopy (VAEM) in dissecting protein dynamics in plant cells. The VAEM-based co-localization analysis took penetration depth and incident angle into consideration. Besides direct overlap of dual-color fluorescence signals, the co-localization analysis was carried out quantitatively in combination with the methodology for calculating puncta distance and protein proximity index. Besides, simultaneous VAEM tracking of cytoskeletal dynamics provided more insights into coordinated responses of actin filaments and microtubules. Moreover, lateral motility of membrane proteins was analyzed by calculating diffusion coefficients and kymograph analysis, which represented an alternative method for examining protein motility. The present study presented experimental evidence on illustrating the use of VAEM in tracking and dissecting protein dynamics, dissecting endosomal dynamics, cell structure assembly along with membrane microdomain and protein motility in intact plant cells.

The SU(2) action-angle variables

NASA Technical Reports Server (NTRS)

Ellinas, Demosthenes

1993-01-01

Operator angle-action variables are studied in the frame of the SU(2) algebra, and their eigenstates and coherent states are discussed. The quantum mechanical addition of action-angle variables is shown to lead to a noncommutative Hopf algebra. The group contraction is used to make the connection with the harmonic oscillator.

Surface compositional variation on the comet 67P/Churyumov-Gerasimenko by OSIRIS data

NASA Astrophysics Data System (ADS)

Barucci, M. A.; Fornasier, S.; Feller, C.; Perna, D.; Hasselmann, H.; Deshapriya, J. D. P.; Fulchignoni, M.; Besse, S.; Sierks, H.; Forgia, F.; Lazzarin, M.; Pommerol, A.; Oklay, N.; Lara, L.; Scholten, F.; Preusker, F.; Leyrat, C.; Pajola, M.; Osiris-Rosetta Team

2015-10-01

Since the Rosetta mission arrived at the comet 67P/Churyumov-Gerasimenko (67/P C-G) on July 2014, the comet nucleus has been mapped by both OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System, [1]) NAC (Narrow Angle Camera) and WAC (Wide Angle Camera) acquiring a huge quantity of surface's images at different wavelength bands, under variable illumination conditions and spatial resolution, and producing the most detailed maps at the highest spatial resolution of a comet nucleus surface.67/P C-G's nucleus shows an irregular bi-lobed shape of complex morphology with terrains showing intricate features [2, 3] and a heterogeneity surface at different scales.

A Conceptual Approach to the Problem of Action-Angle Variables

NASA Astrophysics Data System (ADS)

Zung, Nguyen Tien

2018-02-01

In this paper we develop a general conceptual approach to the problem of existence of action-angle variables for dynamical systems, which establishes and uses the fundamental conservation property of associated torus actions: anything which is preserved by the system is also preserved by the associated torus actions. This approach allows us to obtain, among other things: (a) the shortest and most easy-to-understand conceptual proof of the classical Arnold-Liouville-Mineur theorem; (b) basically all known results in the literature about the existence of action-angle variables in various contexts can be recovered in a unifying way, with simple proofs, using our approach; (c) new results on action-angle variables in many different contexts, including systems on contact manifolds, systems on presymplectic and Dirac manifolds, action-angle variables near singularities, stochastic systems, and so on. Even when there are no natural action variables, our approach still leads to useful normal forms for dynamical systems, which are not necessarily integrable.

Lower extremity kinematics during walking and elliptical training in individuals with and without traumatic brain injury.

PubMed

Buster, Thad; Burnfield, Judith; Taylor, Adam P; Stergiou, Nicholas

2013-12-01

Elliptical training may be an option for practicing walking-like activity for individuals with traumatic brain injuries (TBI). Understanding similarities and differences between participants with TBI and neurologically healthy individuals during elliptical trainer use and walking may help guide clinical applications incorporating elliptical trainers. Ten participants with TBI and a comparison group of 10 neurologically healthy participants underwent 2 familiarization sessions and 1 data collection session. Kinematic data were collected as participants walked on a treadmill or on an elliptical trainer. Gait-related measures, including coefficient of multiple correlations (a measure of similarity between ensemble joint movement profiles; coefficient of multiple correlations [CMCs]), critical event joint angles, variability of peak critical event joint angles (standard deviations [SDs]) of peak critical event joint angles, and maximum Lyapunov exponents (a measure of the organization of the variability [LyEs]) were compared between groups and conditions. Coefficient of multiple correlations values comparing the similarity in ensemble motion profiles between the TBI and comparison participants exceeded 0.85 for the hip, knee, and ankle joints. The only critical event joint angle that differed significantly between participants with TBI and comparison participants was the ankle during terminal stance. Variability was higher for the TBI group (6 of 11 comparisons significant) compared with comparison participants. Hip and knee joint movement patterns of both participants with TBI and comparison participants on the elliptical trainer were similar to walking (CMCs ≥ 0.87). Variability was higher during elliptical trainer usage compared with walking (5 of 11 comparisons significant). Hip LyEs were higher during treadmill walking. Ankle LyEs were greater during elliptical trainer usage. Movement patterns of participants with TBI were similar to, but more variable than, those of comparison participants while using both the treadmill and the elliptical trainer. If incorporation of complex movements similar to walking is a goal of rehabilitation, elliptical training is a reasonable alternative to treadmill-based training.Video Abstract available (see Video, Supplemental Digital Content 1, http://links.lww.com/JNPT/A65) for more insights from the authors.

Variability in Cobb angle measurements using reformatted computerized tomography scans.

PubMed

Adam, Clayton J; Izatt, Maree T; Harvey, Jason R; Askin, Geoffrey N

2005-07-15

Survey of intraobserver and interobserver measurement variability. To assess the use of reformatted computerized tomography (CT) images for manual measurement of coronal Cobb angles in idiopathic scoliosis. Cobb angle measurements in idiopathic scoliosis are traditionally made from standing radiographs, whereas CT is often used for assessment of vertebral rotation. Correlating Cobb angles from standing radiographs with vertebral rotations from supine CT is problematic because the geometry of the spine changes significantly from standing to supine positions, and 2 different imaging methods are involved. We assessed the use of reformatted thoracolumbar CT images for Cobb angle measurement. Preoperative CT of 12 patients with idiopathic scoliosis were used to generate reformatted coronal images. Five observers measured coronal Cobb angles on 3 occasions from each of the images. Intraobserver and interobserver variability associated with Cobb measurement from reformatted CT scans was assessed and compared with previous studies of measurement variability using plain radiographs. For major curves, 95% confidence intervals for intraobserver and interobserver variability were +/-6.6 degrees and +/-7.7 degrees, respectively. For minor curves, the intervals were +/-7.5 degrees and +/-8.2 degrees, respectively. Intraobserver and interobserver technical error of measurement was 2.4 degrees and 2.7 degrees, with reliability coefficients of 88% and 84%, respectively. There was no correlation between measurement variability and curve severity. Reformatted CT images may be used for manual measurement of coronal Cobb angles in idiopathic scoliosis with similar variability to manual measurement of plain radiographs.

Effects of axial compression and rotation angle on torsional mechanical properties of bovine caudal discs.

PubMed

Bezci, Semih E; Klineberg, Eric O; O'Connell, Grace D

2018-01-01

The intervertebral disc is a complex joint that acts to support and transfer large multidirectional loads, including combinations of compression, tension, bending, and torsion. Direct comparison of disc torsion mechanics across studies has been difficult, due to differences in loading protocols. In particular, the lack of information on the combined effect of multiple parameters, including axial compressive preload and rotation angle, makes it difficult to discern whether disc torsion mechanics are sensitive to the variables used in the test protocol. Thus, the objective of this study was to evaluate compression-torsion mechanical behavior of healthy discs under a wide range of rotation angles. Bovine caudal discs were tested under a range of compressive preloads (150, 300, 600, and 900N) and rotation angles (± 1, 2, 3, 4, or 5°) applied at a rate of 0.5°/s. Torque-rotation data were used to characterize shape changes in the hysteresis loop and to calculate disc torsion mechanics. Torsional mechanical properties were described using multivariate regression models. The rate of change in torsional mechanical properties with compression depended on the maximum rotation angle applied, indicating a strong interaction between compressive stress and maximum rotation angle. The regression models reported here can be used to predict disc torsion mechanics under axial compression for a given disc geometry, compressive preload, and rotation angle. Copyright © 2017 Elsevier Ltd. All rights reserved.

Economy, Movement Dynamics, and Muscle Activity of Human Walking at Different Speeds.

PubMed

Raffalt, P C; Guul, M K; Nielsen, A N; Puthusserypady, S; Alkjær, T

2017-03-08

The complex behaviour of human walking with respect to movement variability, economy and muscle activity is speed dependent. It is well known that a U-shaped relationship between walking speed and economy exists. However, it is an open question if the movement dynamics of joint angles and centre of mass and muscle activation strategy also exhibit a U-shaped relationship with walking speed. We investigated the dynamics of joint angle trajectories and the centre of mass accelerations at five different speeds ranging from 20 to 180% of the predicted preferred speed (based on Froude speed) in twelve healthy males. The muscle activation strategy and walking economy were also assessed. The movement dynamics was investigated using a combination of the largest Lyapunov exponent and correlation dimension. We observed an intermediate stage of the movement dynamics of the knee joint angle and the anterior-posterior and mediolateral centre of mass accelerations which coincided with the most energy-efficient walking speed. Furthermore, the dynamics of the joint angle trajectories and the muscle activation strategy was closely linked to the functional role and biomechanical constraints of the joints.

Relationship among several measurements of slipperiness obtained in a laboratory environment.

PubMed

Chang, Wen-Ruey; Chang, Chien-Chi

2018-04-01

Multiple sensing mechanisms could be used in forming responses to avoid slips, but previous studies, correlating only two parameters, revealed a limited picture of this complex system. In this study, the participants walked as fast as possible without a slip under 15 conditions of different degrees of slipperiness. The relationships among various response parameters, including perceived slipperiness rating, utilized coefficient of friction (UCOF), slipmeter measurement and kinematic parameters, were evaluated. The results showed that the UCOF, perceived rating and heel angle had higher adjusted R 2 values as dependent variables in the multiple linear regressions with the remaining variables in the final pool as independent variables. Although each variable in the final data pool could reflect some measurement of slipperiness, these three variables are more inclusive than others in representing the other variables and were bigger predictors of other variables, so they could be better candidates for measurements of slipperiness. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rotatable spin-polarized electron source for inverse-photoemission experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stolwijk, S. D., E-mail: Sebastian.Stolwijk@wwu.de; Wortelen, H.; Schmidt, A. B.

2014-01-15

We present a ROtatable Spin-polarized Electron source (ROSE) for the use in spin- and angle-resolved inverse-photoemission (SR-IPE) experiments. A key feature of the ROSE is a variable direction of the transversal electron beam polarization. As a result, the inverse-photoemission experiment becomes sensitive to two orthogonal in-plane polarization directions, and, for nonnormal electron incidence, to the out-of-plane polarization component. We characterize the ROSE and test its performance on the basis of SR-IPE experiments. Measurements on magnetized Ni films on W(110) serve as a reference to demonstrate the variable spin sensitivity. Moreover, investigations of the unoccupied spin-dependent surface electronic structure of Tl/Si(111)more » highlight the capability to analyze complex phenomena like spin rotations in momentum space. Essentially, the ROSE opens the way to further studies on complex spin-dependent effects in the field of surface magnetism and spin-orbit interaction at surfaces.« less

Effectiveness of Variable-Gain Kalman Filter Based on Angle Error Calculated from Acceleration Signals in Lower Limb Angle Measurement with Inertial Sensors

PubMed Central

Watanabe, Takashi

2013-01-01

The wearable sensor system developed by our group, which measured lower limb angles using Kalman-filtering-based method, was suggested to be useful in evaluation of gait function for rehabilitation support. However, it was expected to reduce variations of measurement errors. In this paper, a variable-Kalman-gain method based on angle error that was calculated from acceleration signals was proposed to improve measurement accuracy. The proposed method was tested comparing to fixed-gain Kalman filter and a variable-Kalman-gain method that was based on acceleration magnitude used in previous studies. First, in angle measurement in treadmill walking, the proposed method measured lower limb angles with the highest measurement accuracy and improved significantly foot inclination angle measurement, while it improved slightly shank and thigh inclination angles. The variable-gain method based on acceleration magnitude was not effective for our Kalman filter system. Then, in angle measurement of a rigid body model, it was shown that the proposed method had measurement accuracy similar to or higher than results seen in other studies that used markers of camera-based motion measurement system fixing on a rigid plate together with a sensor or on the sensor directly. The proposed method was found to be effective in angle measurement with inertial sensors. PMID:24282442

Structural studies of the formation of lipoplexes between siRNA and selected bis-imidazolium gemini surfactants.

PubMed

Andrzejewska, W; Pietralik, Z; Skupin, M; Kozak, M

2016-10-01

Dicationic (gemini) surfactants are agents that can be used for the preparation of stable complexes of nucleic acids, particularly siRNA for therapeutic purposes. In this study, we demonstrated that bis-imidazolium gemini surfactants with variable lengths of dioxyalkyl linker groups (from dioxyethyl to dioxydodecyl) and dodecyl side chains are excellent for the complexation of siRNA. All of these compounds effectively complexed siRNA in a charge ratio range (p/n) of 1.5-10. The low resolution structure of siRNA oligomers was characterised by small angle scattering of synchrotron radiation (SR-SAXS) and ab initio modelling. The structures of the formed complexes were also analysed using SR-SAXS, circular dichroism studies and electrophoretic mobility tests. The most promising agents for complexation with siRNA were the surfactants that contained dioxyethyl and dioxyhexyl spacer groups. Copyright © 2016 Elsevier B.V. All rights reserved.

Laser-induced breakdown spectra of rock powders at variable ablation and collection angles under Mars-analog conditions

NASA Astrophysics Data System (ADS)

Breves, E. A.; Lepore, K.; Dyar, M. D.; Bender, S. C.; Tokar, R. L.; Boucher, T.

2017-11-01

Laser-induced breakdown spectroscopy has become a popular tool for rapid elemental analysis of geological materials. However, quantitative applications of LIBS are plagued by variability in collected spectra that cannot be attributed to differences in geochemical composition. Even under ideal laboratory conditions, variability in LIBS spectra creates a host of difficulties for quantitative analysis. This is only exacerbated during field work, when both the laser-sample distance and the angle of ablation/collection are constantly changing. A primary goal of this study is to use empirical evidence to provide a more accurate assessment of uncertainty in LIBS-derived element predictions. We hope to provide practical guidance regarding the angles of ablation and collection that can be tolerated without substantially increasing prediction uncertainty beyond that which already exists under ideal laboratory conditions. Spectra were collected from ten geochemically diverse samples at angles of ablation and collection ranging from 0° to ± 60°. Ablation and collection angles were changed independently and simultaneously in order to isolate spectral changes caused by differences in ablation angle from those due to differences in collection angle. Most of the variability in atomic and continuum spectra is attributed to changes in the ablation angle, rather than the collection angle. At higher angles, the irradiance of the laser beam is lower and produces smaller, possibly less dense plasmas. Simultaneous changes in the collection angle do not appear to affect the collected spectra, possibly because smaller plasmas are still within the viewing area of the collection optics, even though this area is reduced at higher collection angles. A key observation is that changes in the magnitude of atomic and total emission are < 5% and 10%, respectively, in spectra collected with the configuration that most closely resembles field measurements (VV) at angles < 20°. In addition, variability in atomic and continuum emission is strongly dependent upon sample composition. Denser, more Fe/Mg-rich rocks exhibited much less variability with changes in ablation and collection angles than Si-rich felsic rocks. Elemental compositions of our variable angle data that were predicted using a much larger but conventionally-collected calibration suite show that accuracy generally suffers when the incidence and collection angles are high. Prediction accuracy (for measurements acquired with varying collection and ablation angles) varies from ± 1.28-1.86 wt% for Al2O3, ± 1.25-1.66 wt% for CaO, ± 1.90-2.21 wt% for Fe2O3T, ± 0.76-0.94 wt% for K2O, ± 2.85-3.61 wt% MgO, ± 0.15-0.17 wt% for MnO, ± 0.68-0.78 wt% for Na2O, ± 0.33-0.42 wt% for TiO2, and ± 2.94-4.34 wt% SiO2. The ChemCam team is using lab data acquired under normal incidence and collection angles to predict the compositions of Mars targets at varying angles. Thus, the increased errors noted in this study for high incidence angle measurements are likely similar to additional, unacknowledged errors on ChemCam results for non-normal targets analyzed on Mars. Optimal quantitative analysis of LIBS spectra must include some knowledge of the angle of ablation and collection so the approximate increase in uncertainty introduced by a departure from normal angles can be accurately reported.

Sensitivity analysis for axis rotation diagrid structural systems according to brace angle changes

NASA Astrophysics Data System (ADS)

Yang, Jae-Kwang; Li, Long-Yang; Park, Sung-Soo

2017-10-01

General regular shaped diagrid structures can express diverse shapes because braces are installed along the exterior faces of the structures and the structures have no columns. However, since irregular shaped structures have diverse variables, studies to assess behaviors resulting from various variables are continuously required to supplement the imperfections related to such variables. In the present study, materials elastic modulus and yield strength were selected as variables for strength that would be applied to diagrid structural systems in the form of Twisters among the irregular shaped buildings classified by Vollers and that affect the structural design of these structural systems. The purpose of this study is to conduct sensitivity analysis for axial rotation diagrid structural systems according to changes in brace angles in order to identify the design variables that have relatively larger effects and the tendencies of the sensitivity of the structures according to changes in brace angles and axial rotation angles.

Comparison of Orbiter PRCS Plume Flow Fields Using CFD and Modified Source Flow Codes

NASA Technical Reports Server (NTRS)

Rochelle, Wm. C.; Kinsey, Robin E.; Reid, Ethan A.; Stuart, Phillip C.; Lumpkin, Forrest E.

1997-01-01

The Space Shuttle Orbiter will use Reaction Control System (RCS) jets for docking with the planned International Space Station (ISS). During approach and backout maneuvers, plumes from these jets could cause high pressure, heating, and thermal loads on ISS components. The object of this paper is to present comparisons of RCS plume flow fields used to calculate these ISS environments. Because of the complexities of 3-D plumes with variable scarf-angle and multi-jet combinations, NASA/JSC developed a plume flow-field methodology for all of these Orbiter jets. The RCS Plume Model (RPM), which includes effects of scarfed nozzles and dual jets, was developed as a modified source-flow engineering tool to rapidly generate plume properties and impingement environments on ISS components. This paper presents flow-field properties from four PRCS jets: F3U low scarf-angle single jet, F3F high scarf-angle single jet, DTU zero scarf-angle dual jet, and F1F/F2F high scarf-angle dual jet. The RPM results compared well with plume flow fields using four CFD programs: General Aerodynamic Simulation Program (GASP), Cartesian (CART), Unified Solution Algorithm (USA), and Reacting and Multi-phase Program (RAMP). Good comparisons of predicted pressures are shown with STS 64 Shuttle Plume Impingement Flight Experiment (SPIFEX) data.

Contemporary skull development - palatal angle analysis.

PubMed

Dostalova, T; Eliasova, H; Gabcova, D; Feberova, J; Kaminek, M

2015-01-01

The palatal angle is an important angle of the craniofacial complex. It is significant for the diagnosis of craniofacial disorders mainly for nasopharyngeal soft-tissue patterns.Background The dentists and otorhinolaryngologists use this relationship to establish proper treatment mechanics and evaluate facial profile. The aims of this study were to provide comparative cephalometric analyses of historical and contemporary skulls. A total of 190 cephalograms of 2 groups of subjects were evaluated. Dolphin Imaging 11.0 - Cephalometric Tracing Analysis was used for the analysis. Unpaired two-tailed t-test assuming equality of variances was used for all variables (at the significance level p = 0.0001). The -modern forensic skulls had larger palatal angle at average value of 8.60 degrees ± 4.35, than that of archeological ones, the average value of which was 6.50 degrees ± 3.92. The difference was found significant. Unpaired two-tailed t-test assuming equality of variances showed that historical and contemporary skulls had statistically significant results. The difference was -2.09 with standard error of 0.60 (95% confidence interval from -3.29 to -0.89). Two-tailed probability attained value of P was less than 0.0001. The difference between both groups was found significant. An increase in the palatal angle can be directly connected with anterior rotation of upper jaw(Tab. 2, Fig. 5, Ref. 19).

Radiographic evaluation of perching-joint angles in cockatiels (Nymphicus hollandicus), Hispaniolan Amazon parrots (Amazona ventralis), and barred owls (Strix varia).

PubMed

Bonin, Glen; Lauer, Susanne K; Guzman, David Sanchez-Migallon; Nevarez, Javier; Tully, Thomas N; Hosgood, Giselle; Gaschen, Lorrie

2009-06-01

Information on perching-joint angles in birds is limited. Joint immobilization in a physiologic perching angle has the potential to result more often in complete restoration of limb function. We evaluated perching-joint angles in 10 healthy cockatiels (Nymphicus hollandicus), 10 Hispaniolan Amazons (Amazona ventralis), and 9 barred owls (Strix varia) and determined intra- and interobserver variability for goniometric measurements in 2 different radiographic projections. Intra- and interobserver variation was less than 7% for all stifle and intertarsal joint measurements but frequently exceeded 10% for the hip-joint measurements. Hip, stifle, and intertarsal perching angles differed significantly among cockatiels, Hispaniolan Amazon parrots, and barred owls. The accuracy of measurements performed on straight lateral radiographic projections with superimposed limbs was not consistently superior to measurements on oblique projections with a slightly rotated pelvis. Stifle and intertarsal joint angles can be measured on radiographs by different observers with acceptable variability, but intra- and interobserver variability for hip-joint-angle measurements is higher.

An oilspill trajectory analysis model with a variable wind deflection angle

USGS Publications Warehouse

Samuels, W.B.; Huang, N.E.; Amstutz, D.E.

1982-01-01

The oilspill trajectory movement algorithm consists of a vector sum of the surface drift component due to wind and the surface current component. In the U.S. Geological Survey oilspill trajectory analysis model, the surface drift component is assumed to be 3.5% of the wind speed and is rotated 20 degrees clockwise to account for Coriolis effects in the Northern Hemisphere. Field and laboratory data suggest, however, that the deflection angle of the surface drift current can be highly variable. An empirical formula, based on field observations and theoretical arguments relating wind speed to deflection angle, was used to calculate a new deflection angle at each time step in the model. Comparisons of oilspill contact probabilities to coastal areas calculated for constant and variable deflection angles showed that the model is insensitive to this changing angle at low wind speeds. At high wind speeds, some statistically significant differences in contact probabilities did appear. ?? 1982.

Conformational divergence in the HA-33/HA-17 trimer of serotype C and D botulinum toxin complex.

PubMed

Sagane, Yoshimasa; Hayashi, Shintaro; Akiyama, Tomonori; Matsumoto, Takashi; Hasegawa, Kimiko; Yamano, Akihito; Suzuki, Tomonori; Niwa, Koichi; Watanabe, Toshihiro; Yajima, Shunsuke

2016-08-05

Clostridium botulinum produces a large toxin complex (L-TC) comprising botulinum neurotoxin associated with auxiliary nontoxic proteins. A complex of 33- and 17-kDa hemagglutinins (an HA-33/HA-17 trimer) enhances L-TC transport across the intestinal epithelial cell layer via binding HA-33 to a sugar on the cell surface. At least two subtypes of serotype C/D HA-33 exhibit differing preferences for the sugars sialic acid and galactose. Here, we compared the three-dimensional structures of the galactose-binding HA-33 and HA-33/HA-17 trimers produced by the C-Yoichi strain. Comparisons of serotype C/D HA-33 sequences reveal a variable region with relatively low sequence similarity across the C. botulinum strains; the variability of this region may influence the manner of sugar-recognition by HA-33. Crystal structures of sialic acid- and galactose-binding HA-33 are broadly similar in appearance. However, small-angle X-ray scattering revealed distinct solution structures for HA-33/HA-17 trimers. A structural change in the C-terminal variable region of HA-33 might cause a dramatic shift in the conformation and sugar-recognition mode of HA-33/HA-17 trimer. Copyright © 2016 Elsevier Inc. All rights reserved.

Effects of B1 inhomogeneity correction for three-dimensional variable flip angle T1 measurements in hip dGEMRIC at 3 T and 1.5 T.

PubMed

Siversson, Carl; Chan, Jenny; Tiderius, Carl-Johan; Mamisch, Tallal Charles; Jellus, Vladimir; Svensson, Jonas; Kim, Young-Jo

2012-06-01

Delayed gadolinium-enhanced MRI of cartilage is a technique for studying the development of osteoarthritis using quantitative T(1) measurements. Three-dimensional variable flip angle is a promising method for performing such measurements rapidly, by using two successive spoiled gradient echo sequences with different excitation pulse flip angles. However, the three-dimensional variable flip angle method is very sensitive to inhomogeneities in the transmitted B(1) field in vivo. In this study, a method for correcting for such inhomogeneities, using an additional B(1) mapping spin-echo sequence, was evaluated. Phantom studies concluded that three-dimensional variable flip angle with B(1) correction calculates accurate T(1) values also in areas with high B(1) deviation. Retrospective analysis of in vivo hip delayed gadolinium-enhanced MRI of cartilage data from 40 subjects showed the difference between three-dimensional variable flip angle with and without B(1) correction to be generally two to three times higher at 3 T than at 1.5 T. In conclusion, the B(1) variations should always be taken into account, both at 1.5 T and at 3 T. Copyright © 2011 Wiley-Liss, Inc.

High-resolution neutron powder diffractometer SPODI at research reactor FRM II

NASA Astrophysics Data System (ADS)

Hoelzel, M.; Senyshyn, A.; Juenke, N.; Boysen, H.; Schmahl, W.; Fuess, H.

2012-03-01

SPODI is a high-resolution thermal neutron diffractometer at the research reactor Heinz Maier-Leibnitz (FRM II) especially dedicated to structural studies of complex systems. Unique features like a very large monochromator take-off angle of 155° and a 5 m monochromator-sample distance in its standard configuration achieve both high-resolution and a good profile shape for a broad scattering angle range. Two dimensional data are collected by an array of 80 vertical position sensitive 3He detectors. SPODI is well suited for studies of complex structural and magnetic order and disorder phenomena at non-ambient conditions. In addition to standard sample environment facilities (cryostats, furnaces, magnet) specific devices (rotatable load frame, cell for electric fields, multichannel potentiostat) were developed. Thus the characterisation of functional materials at in-operando conditions can be achieved. In this contribution the details of the design and present performance of the instrument are reported along with its specifications. A new concept for data reduction using a 2 θ dependent variable height for the intensity integration along the Debye-Scherrer lines is introduced.

The Effect of Camera Angle and Image Size on Source Credibility and Interpersonal Attraction.

ERIC Educational Resources Information Center

McCain, Thomas A.; Wakshlag, Jacob J.

The purpose of this study was to examine the effects of two nonverbal visual variables (camera angle and image size) on variables developed in a nonmediated context (source credibility and interpersonal attraction). Camera angle and image size were manipulated in eight video taped television newscasts which were subsequently presented to eight…

Efficient least angle regression for identification of linear-in-the-parameters models

PubMed Central

Beach, Thomas H.; Rezgui, Yacine

2017-01-01

Least angle regression, as a promising model selection method, differentiates itself from conventional stepwise and stagewise methods, in that it is neither too greedy nor too slow. It is closely related to L1 norm optimization, which has the advantage of low prediction variance through sacrificing part of model bias property in order to enhance model generalization capability. In this paper, we propose an efficient least angle regression algorithm for model selection for a large class of linear-in-the-parameters models with the purpose of accelerating the model selection process. The entire algorithm works completely in a recursive manner, where the correlations between model terms and residuals, the evolving directions and other pertinent variables are derived explicitly and updated successively at every subset selection step. The model coefficients are only computed when the algorithm finishes. The direct involvement of matrix inversions is thereby relieved. A detailed computational complexity analysis indicates that the proposed algorithm possesses significant computational efficiency, compared with the original approach where the well-known efficient Cholesky decomposition is involved in solving least angle regression. Three artificial and real-world examples are employed to demonstrate the effectiveness, efficiency and numerical stability of the proposed algorithm. PMID:28293140

Application of variable-gain output feedback for high-alpha control

NASA Technical Reports Server (NTRS)

Ostroff, Aaron J.

1990-01-01

A variable-gain, optimal, discrete, output feedback design approach that is applied to a nonlinear flight regime is described. The flight regime covers a wide angle-of-attack range that includes stall and post stall. The paper includes brief descriptions of the variable-gain formulation, the discrete-control structure and flight equations used to apply the design approach, and the high performance airplane model used in the application. Both linear and nonlinear analysis are shown for a longitudinal four-model design case with angles of attack of 5, 15, 35, and 60 deg. Linear and nonlinear simulations are compared for a single-point longitudinal design at 60 deg angle of attack. Nonlinear simulations for the four-model, multi-mode, variable-gain design include a longitudinal pitch-up and pitch-down maneuver and high angle-of-attack regulation during a lateral maneuver.

The effect of dimple error on the horizontal launch angle and side spin of the golf ball during putting.

PubMed

Richardson, Ashley K; Mitchell, Andrew C S; Hughes, Gerwyn

2017-02-01

This study aimed to examine the effect of the impact point on the golf ball on the horizontal launch angle and side spin during putting with a mechanical putting arm and human participants. Putts of 3.2 m were completed with a mechanical putting arm (four putter-ball combinations, total of 160 trials) and human participants (two putter-ball combinations, total of 337 trials). The centre of the dimple pattern (centroid) was located and the following variables were measured: distance and angle of the impact point from the centroid and surface area of the impact zone. Multiple regression analysis was conducted to identify whether impact variables had significant associations with ball roll variables, horizontal launch angle and side spin. Significant associations were identified between impact variables and horizontal launch angle with the mechanical putting arm but this was not replicated with human participants. The variability caused by "dimple error" was minimal with the mechanical putting arm and not evident with human participants. Differences between the mechanical putting arm and human participants may be due to the way impulse is imparted on the ball. Therefore it is concluded that variability of impact point on the golf ball has a minimal effect on putting performance.

Apparatus and method for variable angle slant hole collimator

DOEpatents

Lee, Seung Joon; Kross, Brian J.; McKisson, John E.

2017-07-18

A variable angle slant hole (VASH) collimator for providing collimation of high energy photons such as gamma rays during radiological imaging of humans. The VASH collimator includes a stack of multiple collimator leaves and a means of quickly aligning each leaf to provide various projection angles. Rather than rotate the detector around the subject, the VASH collimator enables the detector to remain stationary while the projection angle of the collimator is varied for tomographic acquisition. High collimator efficiency is achieved by maintaining the leaves in accurate alignment through the various projection angles. Individual leaves include unique angled cuts to maintain a precise target collimation angle. Matching wedge blocks driven by two actuators with twin-lead screws accurately position each leaf in the stack resulting in the precise target collimation angle. A computer interface with the actuators enables precise control of the projection angle of the collimator.

Design and Testing of a Morphing Wing for an Experimental UAV

DTIC Science & Technology

2007-11-01

line through the use of conformal flaps [6]. Variable cant angle winglets [7] and variable span wing [8] research has also been made. RTO-MP-AVT...A.Gatto and M.I. Friswell, “The Application of Variable Cant Angle Winglets for Morphing Aircraft Control”, University of Bristol, AIAA2006-3660, 2006

A portable system for foot biomechanical analysis during gait.

PubMed

Samson, William; Sanchez, Stéphane; Salvia, Patrick; Jan, Serge Van Sint; Feipel, Véronique

2014-07-01

Modeling the foot is challenging due to its complex structure compared to most other body segments. To analyze the biomechanics of the foot, portable devices have been designed to allow measurement of temporal, spatial, and pedobarographic parameters. The goal of this study was to design and evaluate a portable system for kinematic and dynamic analysis of the foot during gait. This device consisted of a force plate synchronized with four cameras and integrated into a walkway. The complete system can be packaged for transportation. First, the measurement system was assessed using reference objects to evaluate accuracy and precision. Second, nine healthy participants were assessed during gait trials using both the portable and Vicon systems (coupled with a force plate). The ankle and metatarsophalangeal (MP) joint angles and moments were computed, as well as the ground reaction force (GRF). The intra- and inter-subject variability was analyzed for both systems, as well as the inter-system variation. The accuracy and precision were, respectively 0.4 mm and 0.4 mm for linear values and 0.5° and 0.6° for angular values. The variability of the portable and Vicon systems were similar (i.e., the inter-system variability never exceeded 2.1°, 0.081 Nmkg(-1) and 0.267 Nkg(-1) for the angles, moments and GRF, respectively). The inter-system differences were less than the inter-subject variability and similar to the intra-subject variability. Consequently, the portable system was considered satisfactory for biomechanical analysis of the foot, outside of a motion analysis laboratory. Copyright © 2014 Elsevier B.V. All rights reserved.

Does practicing a wide range of joint angle configurations lead to higher flexibility in a manual obstacle-avoidance target-pointing task?

PubMed Central

Bootsma, Reinoud J.; Schoemaker, Marina M.; Otten, Egbert; Mouton, Leonora J.; Bongers, Raoul M.

2017-01-01

Flexibility in motor actions can be defined as variability in the use of degrees of freedom (e.g., joint angles in the arm) over repetitions while keeping performance (e.g., fingertip position) stabilized. We examined whether flexibility can be increased through enlarging the joint angle range during practice in a manual obstacle-avoidance target-pointing task. To establish differences in flexibility we partitioned the variability in joint angles over repetitions in variability within (GEV) and variability outside the solution space (NGEV). More GEV than NGEV reflects flexibility; when the ratio of the GEV and NGEV is higher, flexibility is higher. The pretest and posttest consisted of 30 repetitions of manual pointing to a target while moving over a 10 cm high obstacle. To enlarge the joint angle range during practice participants performed 600 target-pointing movements while moving over obstacles of different heights (5–9 cm, 11–15 cm). The results indicated that practicing movements over obstacles of different heights led participants to use enlarged range of joint angles compared to the range of joint angles used in movements over the 10 cm obstacle in the pretest. However, for each individual obstacle neither joint angle variance nor flexibility were higher during practice. We also did not find more flexibility after practice. In the posttest, joint angle variance was in fact smaller than before practice, primarily in GEV. The potential influences of learning effects and the task used that could underlie the results obtained are discussed. We conclude that with this specific type of practice in this specific task, enlarging the range of joint angles does not lead to more flexibility. PMID:28700695

The correlation between calcaneal valgus angle and asymmetrical thoracic-lumbar rotation angles in patients with adolescent scoliosis.

PubMed

Park, Jaeyong; Lee, Sang Gil; Bae, Jongjin; Lee, Jung Chul

2015-12-01

[Purpose] This study aimed to provide a predictable evaluation method for the progression of scoliosis in adolescents based on quick and reliable measurements using the naked eye, such as the calcaneal valgus angle of the foot, which can be performed at public facilities such as schools. [Subjects and Methods] Idiopathic scoliosis patients with a Cobb's angle of 10° or more (96 females, 22 males) were included in this study. To identify relationships between factors, Pearson's product-moment correlation coefficient was computed. The degree of scoliosis was set as a dependent variable to predict thoracic and lumbar scoliosis using ankle angle and physique factors. Height, weight, and left and right calcaneal valgus angles were set as independent variables; thereafter, multiple regression analysis was performed. This study extracted variables at a significance level (α) of 0.05 by applying a stepwise method, and calculated a regression equation. [Results] Negative correlation (R=-0.266) was shown between lumbar lordosis and asymmetrical lumbar rotation angles. A correlation (R=0.281) was also demonstrated between left calcaneal valgus angles and asymmetrical thoracic rotation angles. [Conclusion] Prediction of scoliosis progress was revealed to be possible through ocular inspection of the calcaneus and Adams forward bending test and the use of a scoliometer.

Decompositions of the polyhedral product functor with applications to moment-angle complexes and related spaces

PubMed Central

Bahri, A.; Bendersky, M.; Cohen, F. R.; Gitler, S.

2009-01-01

This article gives a natural decomposition of the suspension of a generalized moment-angle complex or partial product space which arises as the polyhedral product functor described below. The introduction and application of the smash product moment-angle complex provides a precise identification of the stable homotopy type of the values of the polyhedral product functor. One direct consequence is an analysis of the associated cohomology. For the special case of the complements of certain subspace arrangements, the geometrical decomposition implies the homological decomposition in earlier work of others as described below. Because the splitting is geometric, an analogous homological decomposition for a generalized moment-angle complex applies for any homology theory. Implied, therefore, is a decomposition for the Stanley–Reisner ring of a finite simplicial complex, and natural generalizations. PMID:19620727

Decompositions of the polyhedral product functor with applications to moment-angle complexes and related spaces.

PubMed

Bahri, A; Bendersky, M; Cohen, F R; Gitler, S

2009-07-28

This article gives a natural decomposition of the suspension of a generalized moment-angle complex or partial product space which arises as the polyhedral product functor described below. The introduction and application of the smash product moment-angle complex provides a precise identification of the stable homotopy type of the values of the polyhedral product functor. One direct consequence is an analysis of the associated cohomology. For the special case of the complements of certain subspace arrangements, the geometrical decomposition implies the homological decomposition in earlier work of others as described below. Because the splitting is geometric, an analogous homological decomposition for a generalized moment-angle complex applies for any homology theory. Implied, therefore, is a decomposition for the Stanley-Reisner ring of a finite simplicial complex, and natural generalizations.

Association of spinal deformity and pelvic tilt with gait asymmetry in adolescent idiopathic scoliosis patients: Investigation of ground reaction force.

PubMed

Park, Yang Sun; Lim, Young Tae; Koh, Kyung; Kim, Jong Moon; Kwon, Hyun Joon; Yang, Ji Seung; Shim, Jae Kun

2016-07-01

Adolescent idiopathic scoliosis is a prevalent orthopedic problem in children ages 10 to 16years. Although genetic, physiological and biomechanical factors are considered to contribute to the onset and progression of adolescent idiopathic scoliosis, the underlying mechanisms are not yet clear. The purpose of this study was to investigate the association between spinal deformity and inter-leg ground reaction force asymmetry during walking in adolescent idiopathic scoliosis patients. Fourteen patients (3 males and 11 females) participated in this study. Maximum Cobb's angle, adjusted Cobb's angle, and pelvic tilt were calculated from X-ray images. Asymmetry indices between legs were also calculated from ground reaction force magnitude and time variables from their preferred speed walking. Pearson coefficients of correlation were used to investigate associations of asymmetry indices with angle variables. Asymmetry indices of ground reaction force magnitudes positively correlated with adjusted Cobb's angle and maximum Cobb's angle mainly during the peak of braking phase, average of braking phase, while asymmetry indices of ground reaction force time variables showed no significant correlation with adjusted or maximum Cobb's angle. In contrast, asymmetry indices of ground reaction force time variables positively correlated with pelvic tilt during stance phase. We concluded that the spinal deformity of adolescent idiopathic scoliosis patients estimated using the maximum and adjusted Cobb's angles is generally associated with greater asymmetry of ground reaction force magnitudes in walking, while the pelvic tilt is associated with the greater asymmetry of ground reaction force time variables. Copyright © 2016 Elsevier Ltd. All rights reserved.

Coastline complexity: A parameter for functional classification of coastal environments

USGS Publications Warehouse

Bartley, J.D.; Buddemeier, R.W.; Bennett, D.A.

2001-01-01

To understand the role of the world's coastal zone (CZ) in global biogeochemical fluxes (particularly those of carbon, nitrogen, phosphorus, and sediments) we must generalise from a limited number of observations associated with a few well-studied coastal systems to the global scale. Global generalisation must be based on globally available data and on robust techniques for classification and upscaling. These requirements impose severe constraints on the set of variables that can be used to extract information about local CZ functions such as advective and metabolic fluxes, and differences resulting from changes in biotic communities. Coastal complexity (plan-view tortuosity of the coastline) is a potentially useful parameter, since it interacts strongly with both marine and terrestrial forcing functions to determine coastal energy regimes and water residence times, and since 'open' vs. 'sheltered' categories are important components of most coastal habitat classification schemes. This study employs the World Vector Shoreline (WVS) dataset, originally developed at a scale of 1:250 000. Coastline complexity measures are generated using a modification of the Angle Measurement Technique (AMT), in which the basic measurement is the angle between two lines of specified length drawn from a selected point to the closest points of intersection with the coastline. Repetition of these measurements for different lengths at the same point yields a distribution of angles descriptive of the extent and scale of complexity in the vicinity of that point; repetition of the process at different points on the coast provides a basis for comparing both the extent and the characteristic scale of coastline variation along different reaches of the coast. The coast of northwestern Mexico (Baja California and the Gulf of California) was used as a case study for initial development and testing of the method. The characteristic angle distribution plots generated by the AMT analysis were clustered using LOICZVIEW, a high dimensionality clustering routine developed for large-scale coastal classification studies. The results show distinctive differences in coastal environments that have the potential for interpretation in terms of both biotic and hydrogeochemical environments, and that can be related to the resolution limits and uncertainties of the shoreline data used. These objective, quantitative measures of coastal complexity as a function of scale can be further developed and combined with other data sets to provide a key component of functional classification of coastal environments. ?? 2001 Elsevier Science B.V. All rights reserved.

The influence of lower leg configurations on muscle force variability.

PubMed

Ofori, Edward; Shim, Jaeho; Sosnoff, Jacob J

2018-04-11

The maintenance of steady contractions is required in many daily tasks. However, there is little understanding of how various lower limb configurations influence the ability to maintain force. The purpose of the current investigation was to examine the influence of joint angle on various lower-limb constant force contractions. Nineteen adults performed knee extension, knee flexion, and ankle plantarflexion isometric force contractions to 11 target forces, ranging from 2 to 95% maximal voluntary contraction (MVC) at 2 angles. Force variability was quantified with mean force, standard deviation, and the coefficient of variation of force output. Non-linearities in force output were quantified with approximate entropy. Curve fitting analyses were performed on each set of data from each individual across contractions to further examine whether joint angle interacts with global functions of lower-limb force variability. Joint angle had significant effects on the model parameters used to describe the force-variability function for each muscle contraction (p < 0.05). Regularities in force output were more explained by force level in smaller angle conditions relative to the larger angle conditions (p < 0.05). The findings support the notion that limb configuration influences the magnitude and regularities in force production. Biomechanical factors, such as joint angle, along with neurophysiological factors should be considered together in the discussion of the dynamics of constant force production. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mitigating Uncertainty from Vegetation Spatial Complexity with Highly Portable Lidar

NASA Astrophysics Data System (ADS)

Paynter, I.; Schaaf, C.; Peri, F.; Saenz, E. J.; Genest, D.; Strahler, A. H.; Li, Z.

2015-12-01

To fully utilize the excellent spatial coverage and temporal resolution offered by satellite resources for estimating ecological variables, fine-scale observations are required for comparison, calibration and validation. Lidar instruments have proved effective in estimating the properties of vegetation components of ecosystems, but they are often challenged by occlusion, especially in structurally complex and spatially fragmented ecosystems such as tropical forests. Increasing the range of view angles, both horizontally and vertically, by increasing the number of scans, can mitigate occlusion. However these scans must occur within the window of temporal stability for the ecosystem and vegetation property being measured. The Compact Biomass Lidar (CBL) is a TLS optimized for portability and scanning speed, developed and operated by University of Massachusetts Boston. This 905nm wavelength scanner achieves an angular resolution of 0.25 degrees at a rate of 33 seconds per scan. The ability to acquire many scans within narrow windows of temporal stability for ecological variables has facilitated the more complete investigation of ecosystem structural characteristics, and their expression as a function of view angle. The lightweight CBL has facilitated the use of alternative deployment platforms including towers, trams and masts, allowing analysis of the vertical structure of ecosystems, even in highly enclosed environments such as the sub-canopy of tropical forests where aerial vehicles cannot currently operate. We will present results from view angle analyses of lidar surveys of tropical rainforest in La Selva, Costa Rica where the CBL was deployed at heights up to 10m in Carbono long-term research plots utilizing a portable mast, and on a 25m stationary tower; and temperate forest at Harvard Forest, Massachusetts, USA, where the CBL has been deployed biannually at long-term research plots of hardwood and hemlock, as well as at heights of up to 25m utilizing a stationary tower.

COVARIANCE ESTIMATION USING CONJUGATE GRADIENT FOR 3D CLASSIFICATION IN CRYO-EM.

PubMed

Andén, Joakim; Katsevich, Eugene; Singer, Amit

2015-04-01

Classifying structural variability in noisy projections of biological macromolecules is a central problem in Cryo-EM. In this work, we build on a previous method for estimating the covariance matrix of the three-dimensional structure present in the molecules being imaged. Our proposed method allows for incorporation of contrast transfer function and non-uniform distribution of viewing angles, making it more suitable for real-world data. We evaluate its performance on a synthetic dataset and an experimental dataset obtained by imaging a 70S ribosome complex.

A Robust Parameterization of Human Gait Patterns Across Phase-Shifting Perturbations

PubMed Central

Villarreal, Dario J.; Poonawala, Hasan A.; Gregg, Robert D.

2016-01-01

The phase of human gait is difficult to quantify accurately in the presence of disturbances. In contrast, recent bipedal robots use time-independent controllers relying on a mechanical phase variable to synchronize joint patterns through the gait cycle. This concept has inspired studies to determine if human joint patterns can also be parameterized by a mechanical variable. Although many phase variable candidates have been proposed, it remains unclear which, if any, provide a robust representation of phase for human gait analysis or control. In this paper we analytically derive an ideal phase variable (the hip phase angle) that is provably monotonic and bounded throughout the gait cycle. To examine the robustness of this phase variable, ten able-bodied human subjects walked over a platform that randomly applied phase-shifting perturbations to the stance leg. A statistical analysis found the correlations between nominal and perturbed joint trajectories to be significantly greater when parameterized by the hip phase angle (0.95+) than by time or a different phase variable. The hip phase angle also best parameterized the transient errors about the nominal periodic orbit. Finally, interlimb phasing was best explained by local (ipsilateral) hip phase angles that are synchronized during the double-support period. PMID:27187967

Fourth class of convex equilateral polyhedron with polyhedral symmetry related to fullerenes and viruses

PubMed Central

Schein, Stan; Gayed, James Maurice

2014-01-01

The three known classes of convex polyhedron with equal edge lengths and polyhedral symmetry––tetrahedral, octahedral, and icosahedral––are the 5 Platonic polyhedra, the 13 Archimedean polyhedra––including the truncated icosahedron or soccer ball––and the 2 rhombic polyhedra reported by Johannes Kepler in 1611. (Some carbon fullerenes, inorganic cages, icosahedral viruses, geodesic structures, and protein complexes resemble these fundamental shapes.) Here we add a fourth class, “Goldberg polyhedra,” which are also convex and equilateral. We begin by decorating each of the triangular facets of a tetrahedron, an octahedron, or an icosahedron with the T vertices and connecting edges of a “Goldberg triangle.” We obtain the unique set of internal angles in each planar face of each polyhedron by solving a system of n equations and n variables, where the equations set the dihedral angle discrepancy about different types of edge to zero, and the variables are a subset of the internal angles in 6gons. Like the faces in Kepler’s rhombic polyhedra, the 6gon faces in Goldberg polyhedra are equilateral and planar but not equiangular. We show that there is just a single tetrahedral Goldberg polyhedron, a single octahedral one, and a systematic, countable infinity of icosahedral ones, one for each Goldberg triangle. Unlike carbon fullerenes and faceted viruses, the icosahedral Goldberg polyhedra are nearly spherical. The reasoning and techniques presented here will enable discovery of still more classes of convex equilateral polyhedra with polyhedral symmetry. PMID:24516137

Fourth class of convex equilateral polyhedron with polyhedral symmetry related to fullerenes and viruses.

PubMed

Schein, Stan; Gayed, James Maurice

2014-02-25

The three known classes of convex polyhedron with equal edge lengths and polyhedral symmetry--tetrahedral, octahedral, and icosahedral--are the 5 Platonic polyhedra, the 13 Archimedean polyhedra--including the truncated icosahedron or soccer ball--and the 2 rhombic polyhedra reported by Johannes Kepler in 1611. (Some carbon fullerenes, inorganic cages, icosahedral viruses, geodesic structures, and protein complexes resemble these fundamental shapes.) Here we add a fourth class, "Goldberg polyhedra," which are also convex and equilateral. We begin by decorating each of the triangular facets of a tetrahedron, an octahedron, or an icosahedron with the T vertices and connecting edges of a "Goldberg triangle." We obtain the unique set of internal angles in each planar face of each polyhedron by solving a system of n equations and n variables, where the equations set the dihedral angle discrepancy about different types of edge to zero, and the variables are a subset of the internal angles in 6gons. Like the faces in Kepler's rhombic polyhedra, the 6gon faces in Goldberg polyhedra are equilateral and planar but not equiangular. We show that there is just a single tetrahedral Goldberg polyhedron, a single octahedral one, and a systematic, countable infinity of icosahedral ones, one for each Goldberg triangle. Unlike carbon fullerenes and faceted viruses, the icosahedral Goldberg polyhedra are nearly spherical. The reasoning and techniques presented here will enable discovery of still more classes of convex equilateral polyhedra with polyhedral symmetry.

Age and sex influences on running mechanics and coordination variability.

PubMed

Boyer, Katherine A; Freedman Silvernail, Julia; Hamill, Joseph

2017-11-01

The purpose of this study was to examine the impact of age on running mechanics separately for male and female runners and to quantify sex differences in running mechanics and coordination variability for older runners. Kinematics and kinetics were captured for 20 younger (10 male) and 20 older (10 male) adults running overground at 3.5 m · s -1 . A modified vector coding technique was used to calculate segment coordination variability. Lower extremity joint angles, moments and segment coordination variability were compared between age and sex groups. Significant sex-age interaction effects were found for heel-strike hip flexion and ankle in/eversion angles and peak ankle dorsiflexion angle. In older adults, mid-stance knee flexion angle, ankle inversion and abduction moments and hip abduction and external rotation moments differed by sex. Older compared with younger females had reduced coordination variability in the thigh-shank transverse plane couple but greater coordination variability for the shank rotation-foot eversion couple in early stance. These results suggest there may be a non-equivalent aging process in the movement mechanics for males and females. The age and sex differences in running mechanics and coordination variability highlight the need for sex-based analyses for future studies examining injury risk with age.

Calculated Hydride Donor Abilities of Five-Coordinate Transition Metal Hydrides [HM(diphosphine)2] (+) (M = Ni, Pd, Pt) as a Function of the Bite Angle and Twist Angle of Diphosphine Ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nimlos, Mark R.; Chang, Christopher H.; Curtis, Calvin J.

2008-07-07

Density functional theory (BLYP and B3LYP) and the polarized continuum model (PCM-UA0) for solvation have been used to investigate the effect of bite angle (P-M-P) of diphosphine ligands and the dihedral or twist angle between diphosphine ligands on the hydride donor abilities of Ni, Pd, and Pt [HM(diphosphine)2]+ complexes. It is found that an increased bite angle for a given transition metal atom results in poorer hydride donor abilities. However, hydride donor abilities for these complexes also decrease as the size of the alkyl side groups on the phosphorus atom increase (Et > Me > H) and with the lengthmore » of the metal phosphorus bond (Ni > Pd = Pt). These trends correlate with an increase in the twist angle between the two diphosphine ligands, which increases from 0° for a square-planar configuration to 90° for a tetrahedral geometry. Shorter M-P bonds, larger substituents on the diphosphine ligands, and larger bite angles all result in increased steric interactions between diphosphine ligands and larger dihedral or twist angles between the diphosphine ligands. The twist angle correlates much more strongly with hydride donor abilities than do bite angles alone. As the twist angle increases, the hydride donor ability decreases in a linear fashion. A frontier orbital analysis has been carried out, and it is shown that the hydride donor ability of [HM(diphosphine)2]+ complexes is largely determined by the energy of the lowest unoccupied molecular orbital of the corresponding [M(diphosphine)2]2+ complex. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.« less

Calculated Hydride Donor Abilities of Five-Coordinate Transition Metal Hydrides [HM(diphosphine)2]+ (M = Ni, Pd, Pt) as a Function of the Bite Angle and Twist Angle of Diphosphine Ligands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nimlos, Mark; Chang, Christopher H.; Curtis, Calvin J.

2008-06-23

Density functional theory (BLYP and B3LYP) and the polarized continuum model (PCM-UA0) for solvation have been used to investigate the effect of bite angle (P-M-P) of diphosphine ligands and the dihedral or twist angle between diphosphine ligands on the hydride donor abilities of Ni, Pd, and Pt [HM(diphosphine)2]+ complexes. It is found that an increased bite angle for a given transition metal atom results in poorer hydride donor abilities. However, hydride donor abilities for these complexes also decrease as the size of the alkyl side groups on the phosphorus atom increase (Et > Me > H) and with the lengthmore » of the metal phosphorus bond (Ni > Pd = Pt). These trends correlate with an increase in the twist angle between the two diphosphine ligands, which increases from 0° for a square-planar configuration to 90° for a tetrahedral geometry. Shorter M-P bonds, larger substituents on the diphosphine ligands, and larger bite angles all result in increased steric interactions between diphosphine ligands and larger dihedral or twist angles between the diphosphine ligands. The twist angle correlates much more strongly with hydride donor abilities than do bite angles alone. As the twist angle increases, the hydride donor ability decreases in a linear fashion. A frontier orbital analysis has been carried out, and it is shown that the hydride donor ability of [HM(diphosphine)2]+ complexes is largely determined by the energy of the lowest unoccupied molecular orbital of the corresponding [M(diphosphine)2]2+ complex. Pacific Northwest National Laboratory is operated by Battelle for the US Department of Energy.« less

Spatial reorientation experiments for NMR of solids and partially oriented liquids.

PubMed

Martin, Rachel W; Kelly, John E; Collier, Kelsey A

2015-11-01

Motional reorientation experiments are extensions of Magic Angle Spinning (MAS) where the rotor axis is changed in order to average out, reintroduce, or scale anisotropic interactions (e.g. dipolar couplings, quadrupolar interactions or chemical shift anisotropies). This review focuses on Variable Angle Spinning (VAS), Switched Angle Spinning (SAS), and Dynamic Angle Spinning (DAS), all of which involve spinning at two or more different angles sequentially, either in successive experiments or during a multidimensional experiment. In all of these experiments, anisotropic terms in the Hamiltonian are scaled by changing the orientation of the spinning sample relative to the static magnetic field. These experiments vary in experimental complexity and instrumentation requirements. In VAS, many one-dimensional spectra are collected as a function of spinning angle. In SAS, dipolar couplings and/or chemical shift anisotropies are reintroduced by switching the sample between two different angles, often 0° or 90° and the magic angle, yielding a two-dimensional isotropic-anisotropic correlation spectrum. Dynamic Angle Spinning (DAS) is a related experiment that is used to simultaneously average out the first- and second-order quadrupolar interactions, which cannot be accomplished by spinning at any unique rotor angle in physical space. Although motional reorientation experiments generally require specialized instrumentation and data analysis schemes, some are accessible with only minor modification of standard MAS probes. In this review, the mechanics of each type of experiment are described, with representative examples. Current and historical probe and coil designs are discussed from the standpoint of how each one accomplishes the particular objectives of the experiment(s) it was designed to perform. Finally, applications to inorganic materials and liquid crystals, which present very different experimental challenges, are discussed. The review concludes with perspectives on how motional reorientation experiments can be applied to current problems in chemistry, molecular biology, and materials science, given the many advances in high-field NMR magnets, fast spinning, and sample preparation realized in recent years. Copyright © 2015 Elsevier B.V. All rights reserved.

Action-angle variables for the harmonic oscillator: Ambiguity spin × duplication spin

NASA Astrophysics Data System (ADS)

de Oliveira, César R.; Malta, Coraci P.

1984-07-01

The difficulties of obtaining for the harmonic oscillator a well-defined unitary transformation to action-angle variables were overcome by M. Moshinsky and T. H. Seligman ( Ann. Phys. (N.Y.)114 (1978), 243) through the introduction of a spinlike variable (ambiguity spin) from a classical point of view. The difficulty of defining a unitary phase operator for the harmonic oscillator was overcome by Roger G. Newton ( Ann. Phys. (N.Y.)124 (1980), 324) also through the introduction of a spinlike variable (named duplication spin by us) but within a quantum framework. Here the relation between the ambiguity spin and the duplication spin is investigated by introducing these two types of spins in the canonical transformation to action-angle variables. In this way both well-defined unitary transformation and phase operators were obtained.

Ability of modern distal tibia plates to stabilize comminuted pilon fracture fragments: Is dual plate fixation necessary?

PubMed

Penny, Phillip; Swords, Michael; Heisler, Jason; Cien, Adam; Sands, Andrew; Cole, Peter

2016-08-01

The purpose of this study was to examine the screw trajectory of ten commercially available distal tibia plates and compare them to common fracture patterns seen in OTA C type pilon fractures to determine their ability to stabilize the three most common fracture fragments while buttressing anterolateral zones of comminution. We hypothesized that a single plate for the distal tibia would fail to adequately stabilize all three main fracture fragments and zones of comminution in complex pilon fractures. Ten synthetic distal tibia sawbones models were used in conjunction with ten different locking distal tibia plate designs from three manufacturers (Depuy Synthes, J&J Co, Paoli, PA; Smith & Nephew, Memphis, TN; and Stryker, Mawa, NJ). Both medial and anterolateral plates from each company were utilized and separately applied to an individual sawbone model. Three implants allowing variable angle screw placement were used. The location of the locking screws and buttress effect 1cm above the articular surface was noted for each implant using axial computed tomography (CT). The images were then compared to a recently published "pilon fracture map" using an overlay technique to establish the relationship between screw location and known common fracture lines and areas of comminution. Each of the three main fragments was considered "captured" by a screw if it was purchased by at least two screws thereby controlling rotational forces on each fragment. Three of four anterolateral plates lacked stable fixation in the medial fragment. Of the 4 anterolateral plates used, only the variable angle anterolateral plate by Depuy Synthes captured the medial fragment with two screws. All four anterolateral plates buttressed the area of highest comminution and had an average of 1.25 screws in the medial fragment and an average of 3 screws in the posterolateral fragment. All five direct medial plates had variable fixation within anterolateral and posterolateral fragments with an average of 1.8 screws in the anterolateral fragment and an average of 1.3 screws in the posterolateral fragment. The Depuy Synthes variable angle anterolateral plate allowed for fixation of the medial fragment with two screws while simultaneously buttressing the zone of highest comminution and capturing both the anterolateral and posterolateral fragments with five and three screws respectively. The variable angle anteromedial plate by Depuy Synthes captured all three main fracture fragments but it did not buttress the anterolateral zone of comminution. In OTA 43C type pilon fractures, 8 out of 10 studied commercially available implants precontoured for the distal tibia, do not adequately stabilize the three primary fracture fragments typically seen in these injuries. Anterolateral plates were superior in addressing the coronal primary fracture line across the apex of the plafond, and buttressing the zone of comminution. None of the available plates can substitute for an understanding of the fracture planes and fragments typically seen in complex intra-articular tibia fractures and the addition of a second plate is necessary for adequate stability. Level IV. Copyright © 2016 Elsevier Ltd. All rights reserved.

Open-ocean fish reveal an omnidirectional solution to camouflage in polarized environments.

PubMed

Brady, Parrish C; Gilerson, Alexander A; Kattawar, George W; Sullivan, James M; Twardowski, Michael S; Dierssen, Heidi M; Gao, Meng; Travis, Kort; Etheredge, Robert Ian; Tonizzo, Alberto; Ibrahim, Amir; Carrizo, Carlos; Gu, Yalong; Russell, Brandon J; Mislinski, Kathryn; Zhao, Shulei; Cummings, Molly E

2015-11-20

Despite appearing featureless to our eyes, the open ocean is a highly variable environment for polarization-sensitive viewers. Dynamic visual backgrounds coupled with predator encounters from all possible directions make this habitat one of the most challenging for camouflage. We tested open-ocean crypsis in nature by collecting more than 1500 videopolarimetry measurements from live fish from distinct habitats under a variety of viewing conditions. Open-ocean fish species exhibited camouflage that was superior to that of both nearshore fish and mirrorlike surfaces, with significantly higher crypsis at angles associated with predator detection and pursuit. Histological measurements revealed that specific arrangements of reflective guanine platelets in the fish's skin produce angle-dependent polarization modifications for polarocrypsis in the open ocean, suggesting a mechanism for natural selection to shape reflectance properties in this complex environment. Copyright © 2015, American Association for the Advancement of Science.

Movement pattern recognition in basketball free-throw shooting.

PubMed

Schmidt, Andrea

2012-04-01

The purpose of the present study was to analyze the movement patterns of free-throw shooters in basketball at different skill levels. There were two points of interest. First, to explore what information can be drawn from the movement pattern and second, to examine the methodological possibilities of pattern analysis. To this end, several qualitative and quantitative methods were employed. The resulting data were converged in a triangulation. Using a special kind of ANN named Dynamically Controlled Networks (DyCoN), a 'complex feature' consisting of several isolated features (angle displacements and velocities of the articulations of the kinematic chain) was calculated. This 'complex feature' was displayed by a trajectory combining several neurons of the network, reflecting the devolution of the twelve angle measures over the time course of each shooting action. In further network analyses individual characteristics were detected, as well as movement phases. Throwing patterns were successfully classified and the stability and variability of the realized pattern were established. The movement patterns found were clearly individually shaped as well as formed by the skill level. The triangulation confirmed the individual movement organizations. Finally, a high stability of the network methods was documented. Copyright © 2012. Published by Elsevier B.V.

Thermal treatment effects imposed on solid DNA cationic lipid complex with hexadecyltrimethylammonium chloride, observed by variable angle spectroscopic ellipsometry

NASA Astrophysics Data System (ADS)

Nizioł, Jacek

2014-12-01

DNA cationic lipid complexes are materials of properties required for applications in organic electronics and optoelectronics. Often, their thermal stability demonstrated by thermogravimetry is cited in the literature as important issue. However, little is known about processes occurring in heated solid DNA cationic lipid complexes. In frame of this work, thin films of Deoxyribonucleic acid-hexadecyltrimethylammonium chloride (DNA-CTMA) were deposited on silicon wafers. Samples were thermally annealed, and simultaneously, their optical functions were measured by spectroscopic ellipsometry. At lower temperatures, thermal expansion coefficient of solid DNA-CTMA was negative, but at higher temperatures positive. Thermally induced modification of absorption spectrum in UV-vis was observed. It occurred at a range of temperatures higher than this of DNA denaturation in solution. The observed phenomenon was irreversible, at least in time scale of the experiment (one day).

Evaluation of complex gonioapparent samples using a bidirectional spectrometer.

PubMed

Rogelj, Nina; Penttinen, Niko; Gunde, Marta Klanjšek

2015-08-24

Many applications use gonioapparent targets whose appearance depends on irradiation and viewing angles; the strongest effects are provided by light diffraction. These targets, optically variable devices (OVDs), are used in both security and authentication applications. This study introduces a bidirectional spectrometer, which enables to analyze samples with most complex angular and spectral properties. In our work, the spectrometer is evaluated with samples having very different types of reflection, concerning spectral and angular distributions. Furthermore, an OVD containing several different grating patches is evaluated. The device uses automatically adjusting exposure time to provide maximum signal dynamics and is capable of doing steps as small as 0.01°. However, even 2° steps for the detector movement showed that this device is more than capable of characterizing even the most complex reflecting surfaces. This study presents sRGB visualizations, discussion of bidirectional reflection, and accurate grating period calculations for all of the grating samples used.

Nonlinear d10-ML2 Transition-Metal Complexes

PubMed Central

Wolters, Lando P; Bickelhaupt, F Matthias

2013-01-01

We have investigated the molecular geometries of a series of dicoordinated d10-transition-metal complexes ML2 (M=Co−, Rh−, Ir−, Ni, Pd, Pt, Cu+, Ag+, Au+; L=NH3, PH3, CO) using relativistic density functional theory (DFT) at ZORA-BLYP/TZ2P. Not all complexes have the expected linear ligand–metal–ligand (L–M–L) angle: this angle varies from 180° to 128.6° as a function of the metal as well as the ligands. Our main objective is to present a detailed explanation why ML2 complexes can become bent. To this end, we have analyzed the bonding mechanism in ML2 as a function of the L–M–L angle using quantitative Kohn–Sham molecular orbital (MO) theory in combination with an energy decomposition analysis (EDA) scheme. The origin of bent L–M–L structures is π backdonation. In situations of strong π backdonation, smaller angles increase the overlap of the ligand’s acceptor orbital with a higher-energy donor orbital on the metal-ligand fragment, and therefore favor π backdonation, resulting in additional stabilization. The angle of the complexes thus depends on the balance between this additional stabilization and increased steric repulsion that occurs as the complexes are bent. PMID:24551547

Rapid assessment of pulmonary gas transport with hyperpolarized 129Xe MRI using a 3D radial double golden-means acquisition with variable flip angles.

PubMed

Ruppert, Kai; Amzajerdian, Faraz; Hamedani, Hooman; Xin, Yi; Loza, Luis; Achekzai, Tahmina; Duncan, Ian F; Profka, Harrilla; Siddiqui, Sarmad; Pourfathi, Mehrdad; Cereda, Maurizio F; Kadlecek, Stephen; Rizi, Rahim R

2018-04-22

To demonstrate the feasibility of using a 3D radial double golden-means acquisition with variable flip angles to monitor pulmonary gas transport in a single breath hold with hyperpolarized xenon-129 MRI. Hyperpolarized xenon-129 MRI scans with interleaved gas-phase and dissolved-phase excitations were performed using a 3D radial double golden-means acquisition in mechanically ventilated rabbits. The flip angle was either held fixed at 15 ° or 5 °, or it was varied linearly in ascending or descending order between 5 ° and 15 ° over a sampling interval of 1000 spokes. Dissolved-phase and gas-phase images were reconstructed at high resolution (32 × 32 × 32 matrix size) using all 1000 spokes, or at low resolution (22 × 22 × 22 matrix size) using 400 spokes at a time in a sliding-window fashion. Based on these sliding-window images, relative change maps were obtained using the highest mean flip angle as the reference, and aggregated pixel-based changes were tracked. Although the signal intensities in the dissolve-phase maps were mostly constant in the fixed flip-angle acquisitions, they varied significantly as a function of average flip angle in the variable flip-angle acquisitions. The latter trend reflects the underlying changes in observed dissolve-phase magnetization distribution due to pulmonary gas uptake and transport. 3D radial double golden-means acquisitions with variable flip angles provide a robust means for rapidly assessing lung function during a single breath hold, thereby constituting a particularly valuable tool for imaging uncooperative or pediatric patient populations. © 2018 International Society for Magnetic Resonance in Medicine.

Pilot Preferences on Displayed Aircraft Control Variables

NASA Technical Reports Server (NTRS)

Trujillo, Anna C.; Gregory, Irene M.

2013-01-01

The experiments described here explored how pilots want available maneuver authority information transmitted and how this information affects pilots before and after an aircraft failure. The aircraft dynamic variables relative to flight performance were narrowed to energy management variables. A survey was conducted to determine what these variables should be. Survey results indicated that bank angle, vertical velocity, and airspeed were the preferred variables. Based on this, two displays were designed to inform the pilot of available maneuver envelope expressed as bank angle, vertical velocity, and airspeed. These displays were used in an experiment involving control surface failures. Results indicate the displayed limitations in bank angle, vertical velocity, and airspeed were helpful to the pilots during aircraft surface failures. However, the additional information did lead to a slight increase in workload, a small decrease in perceived aircraft flying qualities, and no effect on aircraft situation awareness.

Impacted mandibular third molars and their influence on mandibular angle and condyle fractures--a retrospective study.

PubMed

Gaddipati, Rajasekhar; Ramisetty, Sudhir; Vura, Nandagopal; Kanduri, Rajeev Reddy; Gunda, Vinay Kumar

2014-10-01

Previous retrospective analyses prove that impacted mandibular third molars (M3s) increase the risk of angle fractures and decrease the risk of concomitant fractures to the condyle. A retrospective cohort was designed for patients reported to the Department of Oral and Maxillofacial Surgery from January 2011 till June 2013. The study variables are presence or absence of third molar, if it is present, their position, classified using the Pell and Gregory system; angulation, classified using Shiller's method. The outcome variables were angle and condyle fractures. Hospital records and panoramic radiographs were used to determine and classify these variables. The study sample comprised of 118 mandibular angle and condyle fractures in 110 patients. Database was constructed and analysed using SPSS version 10.0. This present retrospective study concluded that the presence of impacted third molar predisposes the angle to fracture and reduces the risk of a concomitant condylar fracture. However absence of impacted third molar increases the risk of condylar fracture. The highest incidence of angle fracture was observed in position A impacted mandibular third molars. And there is no significant relationship, concerning ramus position and angulation of impacted mandibular third molars with the angle fracture. Copyright © 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Computational Study of an Axisymmetric Dual Throat Fluidic Thrust Vectoring Nozzle for a Supersonic Aircraft Application

NASA Technical Reports Server (NTRS)

Deere, Karen A.; Flamm, Jeffrey D.; Berrier, Bobby L.; Johnson, Stuart K.

2007-01-01

A computational investigation of an axisymmetric Dual Throat Nozzle concept has been conducted. This fluidic thrust-vectoring nozzle was designed with a recessed cavity to enhance the throat shifting technique for improved thrust vectoring. The structured-grid, unsteady Reynolds- Averaged Navier-Stokes flow solver PAB3D was used to guide the nozzle design and analyze performance. Nozzle design variables included extent of circumferential injection, cavity divergence angle, cavity length, and cavity convergence angle. Internal nozzle performance (wind-off conditions) and thrust vector angles were computed for several configurations over a range of nozzle pressure ratios from 1.89 to 10, with the fluidic injection flow rate equal to zero and up to 4 percent of the primary flow rate. The effect of a variable expansion ratio on nozzle performance over a range of freestream Mach numbers up to 2 was investigated. Results indicated that a 60 circumferential injection was a good compromise between large thrust vector angles and efficient internal nozzle performance. A cavity divergence angle greater than 10 was detrimental to thrust vector angle. Shortening the cavity length improved internal nozzle performance with a small penalty to thrust vector angle. Contrary to expectations, a variable expansion ratio did not improve thrust efficiency at the flight conditions investigated.

Spherical Coordinate Systems for Streamlining Suited Mobility Analysis

NASA Technical Reports Server (NTRS)

Benson, Elizabeth; Cowley, Matthew S.; Harvill. Lauren; Rajulu, Sudhakar

2014-01-01

When describing human motion, biomechanists generally report joint angles in terms of Euler angle rotation sequences. However, there are known limitations in using this method to describe complex motions such as the shoulder joint during a baseball pitch. Euler angle notation uses a series of three rotations about an axis where each rotation is dependent upon the preceding rotation. As such, the Euler angles need to be regarded as a set to get accurate angle information. Unfortunately, it is often difficult to visualize and understand these complex motion representations. One of our key functions is to help design engineers understand how a human will perform with new designs and all too often traditional use of Euler rotations becomes as much of a hindrance as a help. It is believed that using a spherical coordinate system will allow ABF personnel to more quickly and easily transmit important mobility data to engineers, in a format that is readily understandable and directly translatable to their design efforts. Objectives: The goal of this project is to establish new analysis and visualization techniques to aid in the examination and comprehension of complex motions. Methods: This project consisted of a series of small sub-projects, meant to validate and verify the method before it was implemented in the ABF's data analysis practices. The first stage was a proof of concept, where a mechanical test rig was built and instrumented with an inclinometer, so that its angle from horizontal was known. The test rig was tracked in 3D using an optical motion capture system, and its position and orientation were reported in both Euler and spherical reference systems. The rig was meant to simulate flexion/extension, transverse rotation and abduction/adduction of the human shoulder, but without the variability inherent in human motion. In the second phase of the project, the ABF estimated the error inherent in a spherical coordinate system, and evaluated how this error would vary within the reference frame. This stage also involved expanding a kinematic model of the shoulder, to include the torso, knees, ankle, elbows, wrists and neck. Part of this update included adding a representation of 'roll' about an axis, for upper arm and lower leg rotations. The third stage of the project involved creating visualization methods to assist in interpreting motion in a spherical frame. This visualization method will be incorporated in a tool to evaluate a database of suited mobility data, which is currently in development.

Dosage variability of topical ocular hypotensive products: a densitometric assessment.

PubMed

Gaynes, Bruce I; Singa, Ramesh M; Cao, Ying

2009-02-01

To ascertain consequence of variability in drop volume obtained from multiuse topical ocular hypotensive products in terms of uniformity of product dosage. Densitometric assessment of drop volume dispensed from 2 alternative bottle positions. All except one product demonstrated a statistically significant difference in drop volume when administered at either a 45-degree or 90-degree bottle angle (Student t test, P<0.001). Product-specific drop volume ranged from a nadir of 22.36 microL to a high of 53.54 microL depending on bottle angle of administration. Deviation in drop dose was directly proportional to variability in drop volume. Variability in per drop dosage was conspicuous among products with a coefficient of variation from 1.49% to 15.91%. In accordance with drop volume, all products demonstrated a statistically significant difference in drop dose at 45-degree versus 90-degree administration angles. Drop volume was found unrelated to drop uniformity (Spearman r=0.01987 and P=0.9463). Variability and lack of uniformity in drop dosage is clearly evident among select ocular hypotensive products and is related to angle of drop administration. Erratic dosage of topical ocular hypotensive therapy may contribute in part to therapeutic failure and/or toxicity.

Contribution of Lateral Column Lengthening to Correction of Forefoot Abduction in Stage IIb Adult Acquired Flatfoot Deformity Reconstruction.

PubMed

Chan, Jeremy Y; Greenfield, Stephen T; Soukup, Dylan S; Do, Huong T; Deland, Jonathan T; Ellis, Scott J

2015-12-01

Correction of forefoot abduction in stage IIb adult acquired flatfoot likely depends on the amount of lateral column lengthening (LCL) performed, although this represents only one aspect of a successful reconstruction. The purpose of this study was to evaluate the correlation between common reconstructive variables and the observed change in forefoot abduction. Forty-one patients who underwent flatfoot reconstruction involving an Evans-type LCL were assessed retrospectively. Preoperative and postoperative anteroposterior (AP) radiographs of the foot at a minimum of 40 weeks (mean, 2 years) after surgery were reviewed to determine correction in forefoot abduction as measured by talonavicular coverage (TNC) angle, talonavicular uncoverage percent, talus-first metatarsal (T-1MT) angle, and lateral incongruency angle. Fourteen demographic and intraoperative variables were evaluated for association with change in forefoot abduction including age, gender, height, weight, body mass index, as well as the amount of LCL and medializing calcaneal osteotomy performed, LCL graft type, Cotton osteotomy, first tarsometatarsal fusion, flexor digitorum longus transfer, spring ligament repair, gastrocnemius recession and any one of the modified McBride/Akin/Silver procedures. Two variables significantly affected the change in lateral incongruency angle. These were weight (P = .04) and the amount of LCL performed (P < .001). No variables were associated with the change in TNC angle, talonavicular uncoverage percent, or T-1MT angle. Multivariate regression analysis revealed that LCL was the only significant predictor of the change in lateral incongruency angle. The final regression model for LCL showed a good fit (R2 = 0.70, P < .001). Each millimeter of LCL corresponded to a 6.8-degree change in lateral incongruency angle. Correction of forefoot abduction in flatfoot reconstruction was primarily determined by the LCL procedure and could be modeled linearly. We believe that the lateral incongruency angle can serve as a valuable preoperative measurement to help surgeons titrate the proper amount of correction performed intraoperatively. © The Author(s) 2015.

Mechanics of Cellulose Synthase Complexes in Living Plant Cells

NASA Astrophysics Data System (ADS)

Zehfroosh, Nina; Liu, Derui; Ramos, Kieran P.; Yang, Xiaoli; Goldner, Lori S.; Baskin, Tobias I.

The polymer cellulose is one of the major components of the world's biomass with unique and fascinating characteristics such as its high tensile strength, renewability, biodegradability, and biocompatibility. Because of these distinctive aspects, cellulose has been the subject of enormous scientific and industrial interest, yet there are still fundamental open questions about cellulose biosynthesis. Cellulose is synthesized by a complex of transmembrane proteins called ``Cellulose Synthase A'' (CESA) in the plasma membrane. Studying the dynamics and kinematics of the CESA complex will help reveal the mechanism of cellulose synthesis and permit the development and validation of models of CESA motility. To understand what drives these complexes through the cell membrane, we used total internal reflection fluorescence microscopy (TIRFM) and variable angle epi-fluorescence microscopy to track individual, fluorescently-labeled CESA complexes as they move in the hypocotyl and root of living plants. A mean square displacement analysis will be applied to distinguish ballistic, diffusional, and other forms of motion. We report on the results of these tracking experiments. This work was funded by NSF/PHY-1205989.

Asymptotics of action variables near semi-toric singularities

NASA Astrophysics Data System (ADS)

Wacheux, Christophe

2015-12-01

The presence of focus-focus singularities in semi-toric integrables Hamiltonian systems is one of the reasons why there cannot exist global Action-Angle coordinates on such systems. At focus-focus critical points, the Liouville-Arnold-Mineur theorem does not apply. In particular, the affine structure of the image of the moment map around has non-trivial monodromy. In this article, we establish that the singular behavior and the multi-valuedness of the Action integrals is given by a complex logarithm. This extends a previous result by San Vũ Ngọc to any dimension. We also calculate the monodromy matrix for these systems.

NNLOPS accurate associated HW production

NASA Astrophysics Data System (ADS)

Astill, William; Bizon, Wojciech; Re, Emanuele; Zanderighi, Giulia

2016-06-01

We present a next-to-next-to-leading order accurate description of associated HW production consistently matched to a parton shower. The method is based on reweighting events obtained with the HW plus one jet NLO accurate calculation implemented in POWHEG, extended with the MiNLO procedure, to reproduce NNLO accurate Born distributions. Since the Born kinematics is more complex than the cases treated before, we use a parametrization of the Collins-Soper angles to reduce the number of variables required for the reweighting. We present phenomenological results at 13 TeV, with cuts suggested by the Higgs Cross section Working Group.

Fourier decomposition pulmonary MRI using a variable flip angle balanced steady-state free precession technique.

PubMed

Corteville, D M R; Kjïrstad, Å; Henzler, T; Zöllner, F G; Schad, L R

2015-05-01

Fourier decomposition (FD) is a noninvasive method for assessing ventilation and perfusion-related information in the lungs. However, the technique has a low signal-to-noise ratio (SNR) in the lung parenchyma. We present an approach to increase the SNR in both morphological and functional images. The data used to create functional FD images are usually acquired using a standard balanced steady-state free precession (bSSFP) sequence. In the standard sequence, the possible range of the flip angle is restricted due to specific absorption rate (SAR) limitations. Thus, using a variable flip angle approach as an optimization is possible. This was validated using measurements from a phantom and six healthy volunteers. The SNR in both the morphological and functional FD images was increased by 32%, while the SAR restrictions were kept unchanged. Furthermore, due to the higher SNR, the effective resolution of the functional images was increased visibly. The variable flip angle approach did not introduce any new transient artifacts, and blurring artifacts were minimized. Both a gain in SNR and an effective resolution gain in functional lung images can be obtained using the FD method in conjunction with a variable flip angle optimized bSSFP sequence. © 2014 Wiley Periodicals, Inc.

Reef flattening effects on total richness and species responses in the Caribbean.

PubMed

Newman, Steven P; Meesters, Erik H; Dryden, Charlie S; Williams, Stacey M; Sanchez, Cristina; Mumby, Peter J; Polunin, Nicholas V C

2015-11-01

There has been ongoing flattening of Caribbean coral reefs with the loss of habitat having severe implications for these systems. Complexity and its structural components are important to fish species richness and community composition, but little is known about its role for other taxa or species-specific responses. This study reveals the importance of reef habitat complexity and structural components to different taxa of macrofauna, total species richness, and individual coral and fish species in the Caribbean. Species presence and richness of different taxa were visually quantified in one hundred 25-m(2) plots in three marine reserves in the Caribbean. Sampling was evenly distributed across five levels of visually estimated reef complexity, with five structural components also recorded: the number of corals, number of large corals, slope angle, maximum sponge and maximum octocoral height. Taking advantage of natural heterogeneity in structural complexity within a particular coral reef habitat (Orbicella reefs) and discrete environmental envelope, thus minimizing other sources of variability, the relative importance of reef complexity and structural components was quantified for different taxa and individual fish and coral species on Caribbean coral reefs using boosted regression trees (BRTs). Boosted regression tree models performed very well when explaining variability in total (82·3%), coral (80·6%) and fish species richness (77·3%), for which the greatest declines in richness occurred below intermediate reef complexity levels. Complexity accounted for very little of the variability in octocorals, sponges, arthropods, annelids or anemones. BRTs revealed species-specific variability and importance for reef complexity and structural components. Coral and fish species occupancy generally declined at low complexity levels, with the exception of two coral species (Pseudodiploria strigosa and Porites divaricata) and four fish species (Halichoeres bivittatus, H. maculipinna, Malacoctenus triangulatus and Stegastes partitus) more common at lower reef complexity levels. A significant interaction between country and reef complexity revealed a non-additive decline in species richness in areas of low complexity and the reserve in Puerto Rico. Flattening of Caribbean coral reefs will result in substantial species losses, with few winners. Individual structural components have considerable value to different species, and their loss may have profound impacts on population responses of coral and fish due to identity effects of key species, which underpin population richness and resilience and may affect essential ecosystem processes and services. © 2015 The Authors. Journal of Animal Ecology © 2015 British Ecological Society.

Correlation between Topographic Parameters Obtained by Back Surface Topography Based on Structured Light and Radiographic Variables in the Assessment of Back Morphology in Young Patients with Idiopathic Scoliosis.

PubMed

Pino-Almero, Laura; Mínguez-Rey, María Fe; Cibrián-Ortiz de Anda, Rosa María; Salvador-Palmer, María Rosario; Sentamans-Segarra, Salvador

2017-04-01

Optical cross-sectional study. To study the correlation between asymmetry of the back (measured by means of surface topography) and deformity of the spine (quantified by the Cobb angle). The Cobb angle is considered the gold standard in diagnosis and follow-up of scoliosis but does not correctly characterize the three-dimensional deformity of scoliosis. Furthermore, the exposure to ionizing radiation may cause harmful effects particularly during the growth stage, including breast cancer and other tumors. Patients aged 13.15±1.96 years (range, 7-17 years; n=88) with Cobb angle greater than 10° were evaluated with X-rays and our back surface topography method through three variables: axial plane (DHOPI), coronal plane (POTSI), and profile plane (PC). Pearson's correlation was applied to determine the correlation between topographic and radiographic variables. One-way analysis of variance and Bonferroni correction were used to compare groups with different grades of scoliosis. Significance was set at p <0.01 and, in some cases, at p <0.05. We detected a positive, statistically significant correlation between Cobb angle with DHOPI ( r =0.810) and POTSI ( r =0.629) and between PC variables with thoracic kyphosis angle ( r =0.453) and lordosis lumbar angle ( r =0.275). In addition, we found statistically significant differences for DHOPI and POTSI variables according to the grade of scoliosis. Although the back surface topography method cannot substitute for radiographs in the diagnosis of scoliosis, correlations between radiographic and topographic parameters suggest that it offers additional quantitative data that may complement radiologic study.

Extensional tectonics during the igneous emplacement of the mafic-ultramafic rocks of the Barberton greenstone belt

NASA Technical Reports Server (NTRS)

Dewit, M. J.

1986-01-01

The simatic rocks (Onverwacht Group) of the Barberton greenstone belt are part of the Jamestown ophiolite complex. This ophiolite, together with its thick sedimentary cover occupies a complex thrust belt. Field studies have identified two types of early faults which are entirely confined to the simatic rocks and are deformed by the later thrusts and associated folds. The first type of fault (F1a) is regional and always occurs in the simatic rocks along and parallel to the lower contacts of the ophiolite-related cherts (Middle Marker and equivalent layers). These fault zones have previously been referred to both as flaser-banded gneisses and as weathering horizons. In general the zones range between 1-30m in thickness. Displacements along these zones are difficult to estimate, but may be in the order of 1-100 km. The structures indicate that the faults formed close to horizontal, during extensional shear and were therefore low angle normal faults. F1a zones overlap in age with the formation of the ophiolite complex. The second type of faults (F1b) are vertical brittle-ductile shear zones, which crosscut the complex at variable angles and cannot always be traced from plutonic to overlying extrusive (pillowed) simatic rocks. F1b zones are also apparently of penecontemporaneous origin with the intrusive-extrusive igneous processs. F1b zones may either represent transform fault-type activity or represent root zones (steepened extensions) of F1a zones. Both fault types indicate extensive deformation in the rocks of the greenstone belt prior to compressional overthrust tectonics.

Longitudinal Changes of Angle Configuration in Primary Angle-Closure Suspects

PubMed Central

Jiang, Yuzhen; Chang, Dolly S.; Zhu, Haogang; Khawaja, Anthony P.; Aung, Tin; Huang, Shengsong; Chen, Qianyun; Munoz, Beatriz; Grossi, Carlota M.

2015-01-01

Objective To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. Design Longitudinal cohort study. Participants Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. Methods Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. Main Outcome Measures Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. Results No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months after LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant for angle width measured under gonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8–1.6) in treated eyes and 1.6°/year (95% CI, 1.3–2.0) in untreated eyes (P<0.001). Conclusions Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period. PMID:24835757

Orthodontic camouflage versus orthognathic surgery for class III deformity: comparative cephalometric analysis.

PubMed

Martinez, P; Bellot-Arcís, C; Llamas, J M; Cibrian, R; Gandia, J L; Paredes-Gallardo, V

2017-04-01

The objective of this study was to compare different cephalometric variables in adult patients with class III malocclusions before and after treatment, in order to determine which variables are indicative of orthodontic camouflage or orthognathic surgery. The cases of 156 adult patients were assessed: 77 treated with orthodontic camouflage and 79 treated with orthodontics and orthognathic surgery. The following cephalometric variables were measured on pre-treatment (T1) and post-treatment (T2) lateral cephalograms: sella-nasion-A-point (SNA), sella-nasion-B-point (SNB), and A-point-nasion-B-point (ANB) angles, Wits appraisal, facial axis angle, mandibular plane angle, upper and lower incisor inclination, and inter-incisal angle. There were statistically significant differences in cephalometric variables before and after treatment between the two groups. The percentage of normal pre-treatment measurements in the camouflage orthodontics group was 30.7%, which worsened slightly to 28.4% post-treatment. However in the group receiving surgery, this was 24.5% pre-treatment, improving to 33.5% after surgery. SNA, SNB, Wits appraisal, lower incisor inclination, and inter-incisal angle showed differences between the two groups before and after treatment. Wits appraisal, lower incisor inclination, and inter-incisal angle were indicative of one or other treatment. Upper and lower incisor decompensation in both groups did not reach ideal values, which impeded complete skeletal correction in 52% of surgical cases. Copyright © 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

Gravity dependence of the effect of optokinetic stimulation on the subjective visual vertical.

PubMed

Ward, Bryan K; Bockisch, Christopher J; Caramia, Nicoletta; Bertolini, Giovanni; Tarnutzer, Alexander Andrea

2017-05-01

Accurate and precise estimates of direction of gravity are essential for spatial orientation. According to Bayesian theory, multisensory vestibular, visual, and proprioceptive input is centrally integrated in a weighted fashion based on the reliability of the component sensory signals. For otolithic input, a decreasing signal-to-noise ratio was demonstrated with increasing roll angle. We hypothesized that the weights of vestibular (otolithic) and extravestibular (visual/proprioceptive) sensors are roll-angle dependent and predicted an increased weight of extravestibular cues with increasing roll angle, potentially following the Bayesian hypothesis. To probe this concept, the subjective visual vertical (SVV) was assessed in different roll positions (≤ ± 120°, steps = 30°, n = 10) with/without presenting an optokinetic stimulus (velocity = ± 60°/s). The optokinetic stimulus biased the SVV toward the direction of stimulus rotation for roll angles ≥ ± 30° ( P < 0.005). Offsets grew from 3.9 ± 1.8° (upright) to 22.1 ± 11.8° (±120° roll tilt, P < 0.001). Trial-to-trial variability increased with roll angle, demonstrating a nonsignificant increase when providing optokinetic stimulation. Variability and optokinetic bias were correlated ( R 2 = 0.71, slope = 0.71, 95% confidence interval = 0.57-0.86). An optimal-observer model combining an optokinetic bias with vestibular input reproduced measured errors closely. These findings support the hypothesis of a weighted multisensory integration when estimating direction of gravity with optokinetic stimulation. Visual input was weighted more when vestibular input became less reliable, i.e., at larger roll-tilt angles. However, according to Bayesian theory, the variability of combined cues is always lower than the variability of each source cue. If the observed increase in variability, although nonsignificant, is true, either it must depend on an additional source of variability, added after SVV computation, or it would conflict with the Bayesian hypothesis. NEW & NOTEWORTHY Applying a rotating optokinetic stimulus while recording the subjective visual vertical in different whole body roll angles, we noted the optokinetic-induced bias to correlate with the roll angle. These findings allow the hypothesis that the established optimal weighting of single-sensory cues depending on their reliability to estimate direction of gravity could be extended to a bias caused by visual self-motion stimuli. Copyright © 2017 the American Physiological Society.

Optimal variable flip angle schemes for dynamic acquisition of exchanging hyperpolarized substrates

NASA Astrophysics Data System (ADS)

Xing, Yan; Reed, Galen D.; Pauly, John M.; Kerr, Adam B.; Larson, Peder E. Z.

2013-09-01

In metabolic MRI with hyperpolarized contrast agents, the signal levels vary over time due to T1 decay, T2 decay following RF excitations, and metabolic conversion. Efficient usage of the nonrenewable hyperpolarized magnetization requires specialized RF pulse schemes. In this work, we introduce two novel variable flip angle schemes for dynamic hyperpolarized MRI in which the flip angle is varied between excitations and between metabolites. These were optimized to distribute the magnetization relatively evenly throughout the acquisition by accounting for T1 decay, prior RF excitations, and metabolic conversion. Simulation results are presented to confirm the flip angle designs and evaluate the variability of signal dynamics across typical ranges of T1 and metabolic conversion. They were implemented using multiband spectral-spatial RF pulses to independently modulate the flip angle at various chemical shift frequencies. With these schemes we observed increased SNR of [1-13C]lactate generated from [1-13C]pyruvate, particularly at later time points. This will allow for improved characterization of tissue perfusion and metabolic profiles in dynamic hyperpolarized MRI.

Three-dimensional optic axis determination using variable-incidence-angle polarization-optical coherence tomography

NASA Astrophysics Data System (ADS)

Ugryumova, Nadezhda; Gangnus, Sergei V.; Matcher, Stephen J.

2006-08-01

Polarization optical coherence tomography (PSOCT) is a powerful technique to nondestructively map the retardance and fast-axis orientation of birefringent biological tissues. Previous studies have concentrated on the case where the optic axis lies on the plane of the surface. We describe a method to determine the polar angle of the optic axis of a uniaxial birefringent tissue by making PSOCT measurements with a number of incident illumination directions. The method is validated on equine flexor tendon, yielding a variability of 4% for the true birefringence and 3% for the polar angle. We use the method to map the polar angle of fibers in the transitional region of equine cartilage.

Predictors of upper trapezius pain with myofascial trigger points in food service workers: The STROBE study.

PubMed

Hwang, Ui-Jae; Kwon, Oh-Yun; Yi, Chung-Hwi; Jeon, Hye-Seon; Weon, Jong-Hyuck; Ha, Sung-Min

2017-06-01

Shoulder pain occurs commonly in food service workers (FSWs) who repetitively perform motions of the upper limbs. Myofascial trigger points (MTrPs) on the upper trapezius (UT) are among the most common musculoskeletal shoulder pain syndromes. This study determined the psychological, posture, mobility, and strength factors associated with pain severity in FSWs with UT pain due to MTrPs.In this cross-sectional study, we measured 17 variables in 163 FSWs with UT pain due to MTrPs: a visual analog scale (VAS) pain score, age, sex, Borg rating of perceived exertion (BRPE) scale, beck depression inventory, forward head posture angle, rounded shoulder angle (RSA), shoulder slope angle, scapular downward rotation ratio, cervical lateral-bending side difference angle, cervical rotation side difference angle, glenohumeral internal rotation angle, shoulder horizontal adduction angle, serratus anterior (SA) strength, lower trapezius (LT) strength, bicep strength, and glenohumeral external rotator strength, in 163 FSWs with UT pain due to MTrPs.The model for factors influencing UT pain with MTrPs included SA strength, age, BRPE, LT strength, and RSA as predictor variables that accounted for 68.7% of the variance in VAS (P < .001) in multiple regression models with a stepwise selection procedure. The following were independent variables influencing the VAS in the order of standardized coefficients: SA strength (β = -0.380), age (β = 0.287), BRPE (β = 0.239), LT strength (β = -0.195), and RSA (β = 0.125).SA strength, age, BRPE, LT strength, and RSA variables should be considered when evaluating and intervening in UT pain with MTrPs in FSWs.

Predictors of upper trapezius pain with myofascial trigger points in food service workers

PubMed Central

Hwang, Ui-Jae; Kwon, Oh-Yun; Yi, Chung-Hwi; Jeon, Hye-Seon; Weon, Jong-Hyuck; Ha, Sung-Min

2017-01-01

Abstract Shoulder pain occurs commonly in food service workers (FSWs) who repetitively perform motions of the upper limbs. Myofascial trigger points (MTrPs) on the upper trapezius (UT) are among the most common musculoskeletal shoulder pain syndromes. This study determined the psychological, posture, mobility, and strength factors associated with pain severity in FSWs with UT pain due to MTrPs. In this cross-sectional study, we measured 17 variables in 163 FSWs with UT pain due to MTrPs: a visual analog scale (VAS) pain score, age, sex, Borg rating of perceived exertion (BRPE) scale, beck depression inventory, forward head posture angle, rounded shoulder angle (RSA), shoulder slope angle, scapular downward rotation ratio, cervical lateral-bending side difference angle, cervical rotation side difference angle, glenohumeral internal rotation angle, shoulder horizontal adduction angle, serratus anterior (SA) strength, lower trapezius (LT) strength, bicep strength, and glenohumeral external rotator strength, in 163 FSWs with UT pain due to MTrPs. The model for factors influencing UT pain with MTrPs included SA strength, age, BRPE, LT strength, and RSA as predictor variables that accounted for 68.7% of the variance in VAS (P < .001) in multiple regression models with a stepwise selection procedure. The following were independent variables influencing the VAS in the order of standardized coefficients: SA strength (β = −0.380), age (β = 0.287), BRPE (β = 0.239), LT strength (β = −0.195), and RSA (β = 0.125). SA strength, age, BRPE, LT strength, and RSA variables should be considered when evaluating and intervening in UT pain with MTrPs in FSWs. PMID:28658117

[Fe(bpb)(CN)2]- as a versatile building block for the design of novel low-dimensional heterobimetallic systems: synthesis, crystal structures, and magnetic properties of cyano-bridged Fe(III)-Ni(II) complexes [(bpb)(2-) = 1,2-bis(pyridine-2-carboxamido)benzenate].

PubMed

Ni, Zhong-Hai; Kou, Hui-Zhong; Zhao, Yi-Hua; Zheng, Lei; Wang, Ru-Ji; Cui, Ai-Li; Sato, Osamu

2005-03-21

A dicyano-containing [Fe(bpb)(CN)2]- building block has been employed for the synthesis of cyano-bridged heterometallic Ni(II)-Fe(III) complexes. The presence of steric bpb(2-) ligand around the iron ion results in the formation of low-dimensional species: five are neutral NiFe2 trimers and three are one-dimensional (1D). The structure of the 1D complexes consists of alternating [NiL]2+ and [Fe(bpb)(CN)2]- generating a cyano-bridged cationic polymeric chain and the perchlorate as the counteranion. In all complexes, the coordination geometry of the nickel ions is approximately octahedral with the cyano nitrogen atoms at the trans positions. Magnetic studies of seven complexes show the presence of ferromagnetic interaction between the metal ions through the cyano bridges. Variable temperature magnetic susceptibility investigations of the trimeric complexes yield the following J(NiFe) values (based on the spin exchange Hamiltonian H = -2J(NiFe) S(Ni) (S(Fe(1)) + S(Fe(2))): J(NiFe) = 6.40(5), 7.8(1), 8.9(2), and 6.03(4) cm(-1), respectively. The study of the magneto-structural correlation reveals that the cyanide-bridging bond angle is related to the strength of magnetic exchange coupling: the larger the Ni-N[triple bond]C bond angle, the stronger the Ni- - -Fe magnetic interaction. One 1D complex exhibits long-range antiferromagnetic ordering with T(N) = 3.5 K. Below T(N) (1.82 K), a metamagnetic behavior was observed with the critical field of approximately 6 kOe. The present research shows that the [Fe(bpb)(CN)2]- building block is a good candidate for the construction of low-dimensional magnetic materials.

A PLL-based resampling technique for vibration analysis in variable-speed wind turbines with PMSG: A bearing fault case

NASA Astrophysics Data System (ADS)

Pezzani, Carlos M.; Bossio, José M.; Castellino, Ariel M.; Bossio, Guillermo R.; De Angelo, Cristian H.

2017-02-01

Condition monitoring in permanent magnet synchronous machines has gained interest due to the increasing use in applications such as electric traction and power generation. Particularly in wind power generation, non-invasive condition monitoring techniques are of great importance. Usually, in such applications the access to the generator is complex and costly, while unexpected breakdowns results in high repair costs. This paper presents a technique which allows using vibration analysis for bearing fault detection in permanent magnet synchronous generators used in wind turbines. Given that in wind power applications the generator rotational speed may vary during normal operation, it is necessary to use special sampling techniques to apply spectral analysis of mechanical vibrations. In this work, a resampling technique based on order tracking without measuring the rotor position is proposed. To synchronize sampling with rotor position, an estimation of the rotor position obtained from the angle of the voltage vector is proposed. This angle is obtained from a phase-locked loop synchronized with the generator voltages. The proposed strategy is validated by laboratory experimental results obtained from a permanent magnet synchronous generator. Results with single point defects in the outer race of a bearing under variable speed and load conditions are presented.

Linear Quadratic Tracking Design for a Generic Transport Aircraft with Structural Load Constraints

NASA Technical Reports Server (NTRS)

Burken, John J.; Frost, Susan A.; Taylor, Brian R.

2011-01-01

When designing control laws for systems with constraints added to the tracking performance, control allocation methods can be utilized. Control allocations methods are used when there are more command inputs than controlled variables. Constraints that require allocators are such task as; surface saturation limits, structural load limits, drag reduction constraints or actuator failures. Most transport aircraft have many actuated surfaces compared to the three controlled variables (such as angle of attack, roll rate & angle of side slip). To distribute the control effort among the redundant set of actuators a fixed mixer approach can be utilized or online control allocation techniques. The benefit of an online allocator is that constraints can be considered in the design whereas the fixed mixer cannot. However, an online control allocator mixer has a disadvantage of not guaranteeing a surface schedule, which can then produce ill defined loads on the aircraft. The load uncertainty and complexity has prevented some controller designs from using advanced allocation techniques. This paper considers actuator redundancy management for a class of over actuated systems with real-time structural load limits using linear quadratic tracking applied to the generic transport model. A roll maneuver example of an artificial load limit constraint is shown and compared to the same no load limitation maneuver.

The lateral boundary of a metamorphic core complex: the Moutsounas shear zone on Naxos, Cyclades, Greece

NASA Astrophysics Data System (ADS)

Cao, S.; Neubauer, F.

2012-04-01

One of the apparently best investigated metamorphic core complexes all over world is that of Naxos in the Aegean Sea and numerous high-quality data on structures and microfabrics have been published. Among these structures is the Naxos-Paros ductile low-angle fault (Gautier et al., 1993), which is located along the northern margin of Naxos and which is part of the North Cycladic Detachment System (Jolivet et al., 2010). There, structural evidence indicates that the hanging wall of the core complex experienced large-scale top-to-the-north (ca. 010°) transport along a low-angle detachment fault. Interestingly no attention has been paid on the well exposed boundary fault on the eastern margin of the Naxos Island, which is even not mentioned in the lierarure. We denote this fault as Moutsounas shear zone, which represents the lateral boundary of the Naxos metamorphic core complex. The Naxos metamorphic core complex is a N-trending elongated dome, which exposes on its eastern side moderately E-dipping micaschists and marbles, which are largely well annealed due to late heating. These annealed rocks grade towards the Moutsounas Peninsula in retrogressed sheared rocks, mostly phyllonitic micaschists and phyllites with an E-dipping foliation and a ca. NNE-trending subhorizontal stretching lineation. Shear bands, asymmetric fringes around rigid clasts and oblique mineralized extension veins consistently indicate top-to-the-NNE shear. The shear zone is structurally overlain by hydrothermally altered Miocene conglomerates, which contain no pebbles from the Naxos metamorphic core complex but exclusively from the ophiolitic hangingwall unit. Miocene rocks are exposed both on the northern and southern edge of the Moutsounas Peninsula. Their bedding is variable but dips generally towards NW, oblique to the detachment fault, which dips with a medium-angle towards east indicating therefore a rollover structure. The Miocene succession is overlain by subhorizontal conglomerates of Pliocene age, which form the main portion of the Moutsounas Peninsula and which contain numerous clasts, mainly marble, of the metamorphic core complex. These sedimentary data indicate that exhumation of the Naxos metamorphic core complex postdate deposition of Miocene successions and predate Pliocene rocks. We interpret the Moutsounas shear zone as a lateral boundary of the Naxos migmatite dome and relate their main activity with top NNE-shear with the main stage of updoming during migmatite formation and granite uplift between ca. 15 and 11 Ma.

Heterogeneous nucleation on convex spherical substrate surfaces: A rigorous thermodynamic formulation of Fletcher's classical model and the new perspectives derived.

PubMed

Qian, Ma; Ma, Jie

2009-06-07

Fletcher's spherical substrate model [J. Chem. Phys. 29, 572 (1958)] is a basic model for understanding the heterogeneous nucleation phenomena in nature. However, a rigorous thermodynamic formulation of the model has been missing due to the significant complexities involved. This has not only left the classical model deficient but also likely obscured its other important features, which would otherwise have helped to better understand and control heterogeneous nucleation on spherical substrates. This work presents a rigorous thermodynamic formulation of Fletcher's model using a novel analytical approach and discusses the new perspectives derived. In particular, it is shown that the use of an intermediate variable, a selected geometrical angle or pseudocontact angle between the embryo and spherical substrate, revealed extraordinary similarities between the first derivatives of the free energy change with respect to embryo radius for nucleation on spherical and flat substrates. Enlightened by the discovery, it was found that there exists a local maximum in the difference between the equivalent contact angles for nucleation on spherical and flat substrates due to the existence of a local maximum in the difference between the shape factors for nucleation on spherical and flat substrate surfaces. This helps to understand the complexity of the heterogeneous nucleation phenomena in a practical system. Also, it was found that the unfavorable size effect occurs primarily when R<5r( *) (R: radius of substrate and r( *): critical embryo radius) and diminishes rapidly with increasing value of R/r( *) beyond R/r( *)=5. This finding provides a baseline for controlling the size effects in heterogeneous nucleation.

Kinematics of a vertical axis wind turbine with a variable pitch angle

NASA Astrophysics Data System (ADS)

Jakubowski, Mateusz; Starosta, Roman; Fritzkowski, Pawel

2018-01-01

A computational model for the kinematics of a vertical axis wind turbine (VAWT) is presented. A H-type rotor turbine with a controlled pitch angle is considered. The aim of this solution is to improve the VAWT productivity. The discussed method is related to a narrow computational branch based on the Blade Element Momentum theory (BEM theory). The paper can be regarded as a theoretical basis and an introduction to further studies with the application of BEM. The obtained torque values show the main advantage of using the variable pitch angle.

The leaf angle distribution of natural plant populations: assessing the canopy with a novel software tool.

PubMed

Müller-Linow, Mark; Pinto-Espinosa, Francisco; Scharr, Hanno; Rascher, Uwe

2015-01-01

Three-dimensional canopies form complex architectures with temporally and spatially changing leaf orientations. Variations in canopy structure are linked to canopy function and they occur within the scope of genetic variability as well as a reaction to environmental factors like light, water and nutrient supply, and stress. An important key measure to characterize these structural properties is the leaf angle distribution, which in turn requires knowledge on the 3-dimensional single leaf surface. Despite a large number of 3-d sensors and methods only a few systems are applicable for fast and routine measurements in plants and natural canopies. A suitable approach is stereo imaging, which combines depth and color information that allows for easy segmentation of green leaf material and the extraction of plant traits, such as leaf angle distribution. We developed a software package, which provides tools for the quantification of leaf surface properties within natural canopies via 3-d reconstruction from stereo images. Our approach includes a semi-automatic selection process of single leaves and different modes of surface characterization via polygon smoothing or surface model fitting. Based on the resulting surface meshes leaf angle statistics are computed on the whole-leaf level or from local derivations. We include a case study to demonstrate the functionality of our software. 48 images of small sugar beet populations (4 varieties) have been analyzed on the base of their leaf angle distribution in order to investigate seasonal, genotypic and fertilization effects on leaf angle distributions. We could show that leaf angle distributions change during the course of the season with all varieties having a comparable development. Additionally, different varieties had different leaf angle orientation that could be separated in principle component analysis. In contrast nitrogen treatment had no effect on leaf angles. We show that a stereo imaging setup together with the appropriate image processing tools is capable of retrieving the geometric leaf surface properties of plants and canopies. Our software package provides whole-leaf statistics but also a local estimation of leaf angles, which may have great potential to better understand and quantify structural canopy traits for guided breeding and optimized crop management.

Parameterisation of non-homogeneities in buried object detection by means of thermography

NASA Astrophysics Data System (ADS)

Stepanić, Josip; Malinovec, Marina; Švaić, Srećko; Krstelj, Vjera

2004-05-01

Landmines and their natural environment form a system of complex dynamics with variable characteristics. A manifestation of that complexity within the context of thermography-based landmines detection is excessive noise in thermograms. That has severely suppressed application of thermography in landmines detection for the purposes of humanitarian demining. (To be differentiated from military demining and demining for military operations other than war [Land Mine Detection DOD's Research Program Needs a Comprehensive Evaluation Strategy, US GAO Report, GAO-01 239, 2001; International Mine Action Standards, Chapter 4.--Glossary. Available at: < http://www.mineactionstandards.org/IMAS_archive/Final/04.10.pdf>].) The discrepancy between the existing role and the actual potential of thermography in humanitarian demining motivated systematic approach to sources of noise in thermograms of buried objects. These sources are variations in mine orientation relative to soil normal, which modify the shape of mine signature on thermograms, as well as non-homogeneities in soil and vegetation layer above the mine, which modify the overall quality of thermograms. This paper analyses the influence of variable mines, and more generally the influence of axially symmetric buried object orientation on the quality of its signature on thermograms. The following two angles have been extracted to serve as parameters describing variation in orientation: (i) θ--angle between the local vertical axis and mine symmetry axis and (ii) ψ--angle between local vertical axis and soil surface normal. Their influence is compared to the influence of (iii) d--the object depth change, which serves as control parameter. The influences are quantified and ranked within a statistically planned experiment. The analysis has proved that among the parameters listed, the most influential one is statistical interaction dψ, followed with the statistical interaction dθ. According to statistical tests, these two combinations are considered the most significant influences. The results show that the currently applied analysis of thermography in humanitarian demining must be broadened by the inclusion of the variations in mine orientation, otherwise a decrease in the probability of mine detection, due to the presence of a systematic error, occurs.

Broad hexagonal columnar mesophases formation in bioinspired transition-metal complexes of simple fatty acid meta-octaester derivatives of meso-tetraphenyl porphyrins.

PubMed

Wu, Bin; Chen, Keyang; Deng, Yuchen; Chen, Jian; Liu, Chengjie; Cheng, Rongshi; Chen, Dongzhong

2015-02-23

A series of meta-substituted fatty acid octaester derivatives and their transition-metal complexes of meso- tetraphenyl porphyrins (TPP-8OOCR, with R = C(n-1)H(2n-1), n = 8, 12, or 16) have been prepared through very simple synthesis protocols. The thermotropic phase behavior and the liquid crystalline (LC) organization structures of the synthesized porphyrin derivatives were systematically investigated by a combination of differential scanning calorimetry (DSC), polarized optical microscopy (POM), and variable-temperature small-angle X-ray scattering/wide-angle X-ray scattering (SAXS/WAXS) techniques. The shorter octanoic acid ester substituted porphyrin (C8-TPP) did not show liquid crystallinity and its metal porphyrins exhibited an uncommon columnar mesophase. The lauric acid octaester (C12-TPP) and the palmitic acid octaester (C16-TPP) series porphyrins generated hexagonal columnar mesophase Colh. Moreover, the metal porphyrins C12-TPPM and C16-TPPM with M = Zn, Cu, or Ni, exhibited well-organized Colh mesophases of broad LC temperature ranges increasing in the order of TPPNi

Sampling saddle points on a free energy surface

NASA Astrophysics Data System (ADS)

Samanta, Amit; Chen, Ming; Yu, Tang-Qing; Tuckerman, Mark; E, Weinan

2014-04-01

Many problems in biology, chemistry, and materials science require knowledge of saddle points on free energy surfaces. These saddle points act as transition states and are the bottlenecks for transitions of the system between different metastable states. For simple systems in which the free energy depends on a few variables, the free energy surface can be precomputed, and saddle points can then be found using existing techniques. For complex systems, where the free energy depends on many degrees of freedom, this is not feasible. In this paper, we develop an algorithm for finding the saddle points on a high-dimensional free energy surface "on-the-fly" without requiring a priori knowledge the free energy function itself. This is done by using the general strategy of the heterogeneous multi-scale method by applying a macro-scale solver, here the gentlest ascent dynamics algorithm, with the needed force and Hessian values computed on-the-fly using a micro-scale model such as molecular dynamics. The algorithm is capable of dealing with problems involving many coarse-grained variables. The utility of the algorithm is illustrated by studying the saddle points associated with (a) the isomerization transition of the alanine dipeptide using two coarse-grained variables, specifically the Ramachandran dihedral angles, and (b) the beta-hairpin structure of the alanine decamer using 20 coarse-grained variables, specifically the full set of Ramachandran angle pairs associated with each residue. For the alanine decamer, we obtain a detailed network showing the connectivity of the minima obtained and the saddle-point structures that connect them, which provides a way to visualize the gross features of the high-dimensional surface.

Variability of surface and center position radiation dose in MDCT: Monte Carlo simulations using CTDI and anthropomorphic phantoms

PubMed Central

Zhang, Di; Savandi, Ali S.; Demarco, John J.; Cagnon, Chris H.; Angel, Erin; Turner, Adam C.; Cody, Dianna D.; Stevens, Donna M.; Primak, Andrew N.; McCollough, Cynthia H.; McNitt-Gray, Michael F.

2009-01-01

The larger coverage afforded by wider z-axis beams in multidetector CT (MDCT) creates larger cone angles and greater beam divergence, which results in substantial surface dose variation for helical and contiguous axial scans. This study evaluates the variation of absorbed radiation dose in both cylindrical and anthropomorphic phantoms when performing helical or contiguous axial scans. The approach used here was to perform Monte Carlo simulations of a 64 slice MDCT. Simulations were performed with different radiation profiles (simulated beam widths) for a given collimation setting (nominal beam width) and for different pitch values and tube start angles. The magnitude of variation at the surface was evaluated under four different conditions: (a) a homogeneous CTDI phantom with different combinations of pitch and simulated beam widths, (b) a heterogeneous anthropomorphic phantom with one measured beam collimation and various pitch values, (c) a homogeneous CTDI phantom with fixed beam collimation and pitch, but with different tube start angles, and (d) pitch values that should minimize variations of surface dose—evaluated for both homogeneous and heterogeneous phantoms. For the CTDI phantom simulations, peripheral dose patterns showed variation with percent ripple as high as 65% when pitch is 1.5 and simulated beam width is equal to the nominal collimation. For the anterior surface dose on an anthropomorphic phantom, the percent ripple was as high as 40% when the pitch is 1.5 and simulated beam width is equal to the measured beam width. Low pitch values were shown to cause beam overlaps which created new peaks. Different x-ray tube start angles create shifts of the peripheral dose profiles. The start angle simulations showed that for a given table position, the surface dose could vary dramatically with minimum values that were 40% of the peak when all conditions are held constant except for the start angle. The last group of simulations showed that an “ideal” pitch value can be determined which reduces surface dose variations, but this pitch value must take into account the measured beam width. These results reveal the complexity of estimating surface dose and demonstrate a range of dose variability at surface positions for both homogeneous cylindrical and heterogeneous anthropomorphic phantoms. These findings have potential implications for small-sized dosimeter measurements in phantoms, such as with TLDs or small Farmer chambers. PMID:19378763

Longitudinal changes of angle configuration in primary angle-closure suspects: the Zhongshan Angle-Closure Prevention Trial.

PubMed

Jiang, Yuzhen; Chang, Dolly S; Zhu, Haogang; Khawaja, Anthony P; Aung, Tin; Huang, Shengsong; Chen, Qianyun; Munoz, Beatriz; Grossi, Carlota M; He, Mingguang; Friedman, David S; Foster, Paul J

2014-09-01

To determine longitudinal changes in angle configuration in the eyes of primary angle-closure suspects (PACS) treated by laser peripheral iridotomy (LPI) and in untreated fellow eyes. Longitudinal cohort study. Primary angle-closure suspects aged 50 to 70 years were enrolled in a randomized, controlled clinical trial. Each participant was treated by LPI in 1 randomly selected eye, with the fellow eye serving as a control. Angle width was assessed in a masked fashion using gonioscopy and anterior segment optical coherence tomography (AS-OCT) before and at 2 weeks, 6 months, and 18 months after LPI. Angle width in degrees was calculated from Shaffer grades assessed under static gonioscopy. Angle configuration was also evaluated using angle opening distance (AOD250, AOD500, AOD750), trabecular-iris space area (TISA500, TISA750), and angle recess area (ARA) measured in AS-OCT images. No significant difference was found in baseline measures of angle configuration between treated and untreated eyes. At 2 weeks after LPI, the drainage angle on gonioscopy widened from a mean of 13.5° at baseline to a mean of 25.7° in treated eyes, which was also confirmed by significant increases in all AS-OCT angle width measures (P<0.001 for all variables). Between 2 weeks and 18 months after LPI, a significant decrease in angle width was observed over time in treated eyes (P<0.001 for all variables), although the change over the first 5.5 months was not statistically significant for angle width measured under gonioscopy (P = 0.18), AOD250 (P = 0.167) and ARA (P = 0.83). In untreated eyes, angle width consistently decreased across all follow-up visits after LPI, with a more rapid longitudinal decrease compared with treated eyes (P values for all variables ≤0.003). The annual rate of change in angle width was equivalent to 1.2°/year (95% confidence interval [CI], 0.8-1.6) in treated eyes and 1.6°/year (95% CI, 1.3-2.0) in untreated eyes (P<0.001). Angle width of treated eyes increased markedly after LPI, remained stable for 6 months, and then decreased significantly by 18 months after LPI. Untreated eyes experienced a more consistent and rapid decrease in angle width over the same time period. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Increased Anterior Pelvic Angle Characterizes the Gait of Children with Attention Deficit/Hyperactivity Disorder (ADHD).

PubMed

Naruse, Hiroaki; Fujisawa, Takashi X; Yatsuga, Chiho; Kubota, Masafumi; Matsuo, Hideaki; Takiguchi, Shinichiro; Shimada, Seiichiro; Imai, Yuto; Hiratani, Michio; Kosaka, Hirotaka; Tomoda, Akemi

2017-01-01

Children with attention deficit/hyperactivity disorder (ADHD) frequently have motor problems. Previous studies have reported that the characteristic gait in children with ADHD is immature and that subjects demonstrate higher levels of variability in gait characteristics for the lower extremities than healthy controls. However, little is known about body movement during gait in children with ADHD. The purpose of this study was to identify the characteristic body movements associated with ADHD symptoms in children with ADHD. Using a three-dimensional motion analysis system, we compared gait variables in boys with ADHD (n = 19; mean age, 9.58 years) and boys with typical development (TD) (n = 21; mean age, 10.71 years) to determine the specific gait characteristics related to ADHD symptoms. We assessed spatiotemporal gait variables (i.e. speed, stride length, and cadence), and kinematic gait variables (i.e. angle of pelvis, hip, knee, and ankle) to measure body movement when walking at a self-selected pace. In comparison with the TD group, the ADHD group demonstrated significantly higher values in cadence (t = 3.33, p = 0.002) and anterior pelvic angle (t = 3.08, p = 0.004). In multiple regression analysis, anterior pelvic angle was associated with the ADHD rating scale hyperactive/impulsive scores (β = 0.62, t = 2.58, p = 0.025), but not other psychiatric symptoms in the ADHD group. Our results suggest that anterior pelvic angle represents a specific gait variable related to ADHD symptoms. Our kinematic findings could have potential implications for evaluating the body movement in boys with ADHD.

Stabilizing detached Bridgman melt crystal growth: Proportional-integral feedback control

NASA Astrophysics Data System (ADS)

Yeckel, Andrew; Daoutidis, Prodromos; Derby, Jeffrey J.

2012-10-01

The dynamics, operability limits, and tuning of a proportional-integral feedback controller to stabilize detached vertical Bridgman crystal growth are analyzed using a capillary model of shape stability. The manipulated variable is the pressure difference between upper and lower vapor spaces, and the controlled variable is the gap width at the triple-phase line. Open and closed loop dynamics of step changes in these state variables are analyzed under both shape stable and shape unstable growth conditions. Effects of step changes in static contact angle and growth angle are also studied. Proportional and proportional-integral control can stabilize unstable growth, but only within tight operability limits imposed by the narrow range of allowed meniscus shapes. These limits are used to establish safe operating ranges of controller gain. Strong nonlinearity of the capillary model restricts the range of perturbations that can be stabilized, and under some circumstances, stabilizes a spurious operating state far from the set point. Stabilizing detachment at low growth angle proves difficult and becomes impossible at zero growth angle.

Aerial photographic water color variations from the James River

NASA Technical Reports Server (NTRS)

Bressette, W. E.

1979-01-01

Photographic flights from 305 meters altitude were made throughout the day of May 17, 1977, over seven water data stations in the James River. The flights resulted in wide-angle, broadband, spectral radiance film exposure data between the wavelengths of 500 to 900 nanometers for sun elevation angles ranging from 37 to 64 deg and variable atmospheric haze conditions. It is shown from densitometer data that: (1) the dominant observed color from James River waters is determined by the optical properties of the total suspended solid load, (2) variability in observed color is produced by a changing solar elevation angle; and (3) the rate at which observed color changes is influenced by both solar elevation angle and atmospheric conditions.

Resolution of ab initio shapes determined from small-angle scattering.

PubMed

Tuukkanen, Anne T; Kleywegt, Gerard J; Svergun, Dmitri I

2016-11-01

Spatial resolution is an important characteristic of structural models, and the authors of structures determined by X-ray crystallography or electron cryo-microscopy always provide the resolution upon publication and deposition. Small-angle scattering of X-rays or neutrons (SAS) has recently become a mainstream structural method providing the overall three-dimensional structures of proteins, nucleic acids and complexes in solution. However, no quantitative resolution measure is available for SAS-derived models, which significantly hampers their validation and further use. Here, a method is derived for resolution assessment for ab initio shape reconstruction from scattering data. The inherent variability of the ab initio shapes is utilized and it is demonstrated how their average Fourier shell correlation function is related to the model resolution. The method is validated against simulated data for proteins with known high-resolution structures and its efficiency is demonstrated in applications to experimental data. It is proposed that henceforth the resolution be reported in publications and depositions of ab initio SAS models.

Resolution of ab initio shapes determined from small-angle scattering

PubMed Central

Tuukkanen, Anne T.; Kleywegt, Gerard J.; Svergun, Dmitri I.

2016-01-01

Spatial resolution is an important characteristic of structural models, and the authors of structures determined by X-ray crystallography or electron cryo-microscopy always provide the resolution upon publication and deposition. Small-angle scattering of X-rays or neutrons (SAS) has recently become a mainstream structural method providing the overall three-dimensional structures of proteins, nucleic acids and complexes in solution. However, no quantitative resolution measure is available for SAS-derived models, which significantly hampers their validation and further use. Here, a method is derived for resolution assessment for ab initio shape reconstruction from scattering data. The inherent variability of the ab initio shapes is utilized and it is demonstrated how their average Fourier shell correlation function is related to the model resolution. The method is validated against simulated data for proteins with known high-resolution structures and its efficiency is demonstrated in applications to experimental data. It is proposed that henceforth the resolution be reported in publications and depositions of ab initio SAS models. PMID:27840683

Convergence of leaf display and photosynthetic characteristics of understory Abies amabilis and Tsuga Heterophylla in an old-growth forest in southwestern Washington State, USA

Treesearch

Hiroaki Ishii; Ken-Ichi Yoshimura; Akira Mori

2009-01-01

The branching pattern of A. amabilis was regular (normal shoot-length distribution, less variable branching angle and bifurcation ratio), whereas that of T. heterophylla was more plastic (positively skewed shoot-length distribution, more variable branching angle and bifurcation ratio). The two species had similar shoot...

Operating Comfort Prediction Model of Human-Machine Interface Layout for Cabin Based on GEP.

PubMed

Deng, Li; Wang, Guohua; Chen, Bo

2015-01-01

In view of the evaluation and decision-making problem of human-machine interface layout design for cabin, the operating comfort prediction model is proposed based on GEP (Gene Expression Programming), using operating comfort to evaluate layout scheme. Through joint angles to describe operating posture of upper limb, the joint angles are taken as independent variables to establish the comfort model of operating posture. Factor analysis is adopted to decrease the variable dimension; the model's input variables are reduced from 16 joint angles to 4 comfort impact factors, and the output variable is operating comfort score. The Chinese virtual human body model is built by CATIA software, which will be used to simulate and evaluate the operators' operating comfort. With 22 groups of evaluation data as training sample and validation sample, GEP algorithm is used to obtain the best fitting function between the joint angles and the operating comfort; then, operating comfort can be predicted quantitatively. The operating comfort prediction result of human-machine interface layout of driller control room shows that operating comfort prediction model based on GEP is fast and efficient, it has good prediction effect, and it can improve the design efficiency.

Operating Comfort Prediction Model of Human-Machine Interface Layout for Cabin Based on GEP

PubMed Central

Wang, Guohua; Chen, Bo

2015-01-01

In view of the evaluation and decision-making problem of human-machine interface layout design for cabin, the operating comfort prediction model is proposed based on GEP (Gene Expression Programming), using operating comfort to evaluate layout scheme. Through joint angles to describe operating posture of upper limb, the joint angles are taken as independent variables to establish the comfort model of operating posture. Factor analysis is adopted to decrease the variable dimension; the model's input variables are reduced from 16 joint angles to 4 comfort impact factors, and the output variable is operating comfort score. The Chinese virtual human body model is built by CATIA software, which will be used to simulate and evaluate the operators' operating comfort. With 22 groups of evaluation data as training sample and validation sample, GEP algorithm is used to obtain the best fitting function between the joint angles and the operating comfort; then, operating comfort can be predicted quantitatively. The operating comfort prediction result of human-machine interface layout of driller control room shows that operating comfort prediction model based on GEP is fast and efficient, it has good prediction effect, and it can improve the design efficiency. PMID:26448740

Wind-Tunnel Investigation of the Effect of Angle of Attack and Flapping-Hinge Offset on Periodic Bending Moments and Flapping of a Small Rotor

NASA Technical Reports Server (NTRS)

McCarty, John Locke; Brooks, George W.; Maglieri, Domenic J.

1959-01-01

A two-blade rotor having a diameter of 4 feet and a solidity of 0.037 was tested in the Langley 300-MPH 7- by 10-foot tunnel to obtain information on the effect of certain rotor variables on the blade periodic bending moments and flapping angles during the various stages of transformation between the helicopter and autogiro configuration. Variables studied included collective pitch angle, flapping-hinge offset, rotor angle of attack, and tip-speed ratio. The results show that the blade periodic bending moments generally increase with tip-speed ratio up into the transition region, diminish over a certain range of tip-speed ratio, and increase again at higher tip-speed ratios. Above the transition region, the bending moments increase with collective pitch angle and rotor angle of attack. The absence of a flapping hinge results in a significant amplification of the periodic bending moments, the magnitudes of which increase with tip-speed ratio. When the flapping hinge is used, an increase in flapping-hinge offset results in reduced period bending moments. The aforementioned trends exhibited by the bending moments for changes in the variables are essentially duplicated by the periodic flapping motions. The existence of substantial amounts of blade stall increased both the periodic bending moments and the flapping angles. Harmonic analysis of the bending moments shows significant contributions of the higher harmonics, particularly in the transition region.

Deep Blue Phosphorescent Organic Light-Emitting Diodes with CIEy Value of 0.11 and External Quantum Efficiency up to 22.5.

PubMed

Li, Xiaoyue; Zhang, Juanye; Zhao, Zifeng; Wang, Liding; Yang, Hannan; Chang, Qiaowen; Jiang, Nan; Liu, Zhiwei; Bian, Zuqiang; Liu, Weiping; Lu, Zhenghong; Huang, Chunhui

2018-03-01

Organic light-emitting diodes (OLEDs) based on red and green phosphorescent iridium complexes are successfully commercialized in displays and solid-state lighting. However, blue ones still remain a challenge on account of their relatively dissatisfactory Commission International de L'Eclairage (CIE) coordinates and low efficiency. After analyzing the reported blue iridium complexes in the literature, a new deep-blue-emitting iridium complex with improved photoluminescence quantum yield is designed and synthesized. By rational screening host materials showing high triplet energy level in neat film as well as the OLED architecture to balance electron and hole recombination, highly efficient deep-blue-emission OLEDs with a CIE at (0.15, 0.11) and maximum external quantum efficiency (EQE) up to 22.5% are demonstrated. Based on the transition dipole moment vector measurement with a variable-angle spectroscopic ellipsometry method, the ultrahigh EQE is assigned to a preferred horizontal dipole orientation of the iridium complex in doped film, which is beneficial for light extraction from the OLEDs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The SCEC 3D Community Fault Model (CFM-v5): An updated and expanded fault set of oblique crustal deformation and complex fault interaction for southern California

NASA Astrophysics Data System (ADS)

Nicholson, C.; Plesch, A.; Sorlien, C. C.; Shaw, J. H.; Hauksson, E.

2014-12-01

Southern California represents an ideal natural laboratory to investigate oblique deformation in 3D owing to its comprehensive datasets, complex tectonic history, evolving components of oblique slip, and continued crustal rotations about horizontal and vertical axes. As the SCEC Community Fault Model (CFM) aims to accurately reflect this 3D deformation, we present the results of an extensive update to the model by using primarily detailed fault trace, seismic reflection, relocated hypocenter and focal mechanism nodal plane data to generate improved, more realistic digital 3D fault surfaces. The results document a wide variety of oblique strain accommodation, including various aspects of strain partitioning and fault-related folding, sets of both high-angle and low-angle faults that mutually interact, significant non-planar, multi-stranded faults with variable dip along strike and with depth, and active mid-crustal detachments. In places, closely-spaced fault strands or fault systems can remain surprisingly subparallel to seismogenic depths, while in other areas, major strike-slip to oblique-slip faults can merge, such as the S-dipping Arroyo Parida-Mission Ridge and Santa Ynez faults with the N-dipping North Channel-Pitas Point-Red Mountain fault system, or diverge with depth. Examples of the latter include the steep-to-west-dipping Laguna Salada-Indiviso faults with the steep-to-east-dipping Sierra Cucapah faults, and the steep southern San Andreas fault with the adjacent NE-dipping Mecca Hills-Hidden Springs fault system. In addition, overprinting by steep predominantly strike-slip faulting can segment which parts of intersecting inherited low-angle faults are reactivated, or result in mutual cross-cutting relationships. The updated CFM 3D fault surfaces thus help characterize a more complex pattern of fault interactions at depth between various fault sets and linked fault systems, and a more complex fault geometry than typically inferred or expected from projecting near-surface data down-dip, or modeled from surface strain and potential field data alone.

Geometry and evolution of low-angle normal faults (LANF) within a Cenozoic high-angle rift system, Thailand: Implications for sedimentology and the mechanisms of LANF development

NASA Astrophysics Data System (ADS)

Morley, Chris K.

2009-10-01

At least eight examples of large (5-35 km heave), low-angle normal faults (LANFs, 20°-30° dip) occur in the Cenozoic rift basins of Thailand and laterally pass into high-angle extensional fault systems. Three large-displacement LANFs are found in late Oligocene-Miocene onshore rift basins (Suphan Buri, Phitsanulok, and Chiang Mai basins), they have (1) developed contemporaneous with, or after the onset of, high-angle extension, (2) acted as paths for magma and associated fluids, and (3) impacted sedimentation patterns. Displacement on low-angle faults appears to be episodic, marked by onset of lacustrine conditions followed by axial progradation of deltaic systems that infilled the lakes during periods of low or no displacement. The Chiang Mai LANF is a low-angle (15°-25°), high-displacement (15-35 km heave), ESE dipping LANF immediately east of the late early Miocene Doi Inthanon and Doi Suthep metamorphic core complexes. Early Cenozoic transpressional crustal thickening followed by the northward motion of India coupled with Burma relative to east Burma and Thailand (˜40-30 Ma) caused migmatization and gneiss dome uplift in the late Oligocene of the core complex region, followed by LANF activity. LANF displacement lasted 4-6 Ma during the early Miocene and possibly transported a late Oligocene-early Miocene high-angle rift system 35 km east. Other LANFs in Thailand have lower displacements and no associated metamorphic core complexes. The three LANFs were initiated as low-angle faults, not by isostatic rotation of high-angle faults. The low-angle dips appear to follow preexisting low-angle fabrics (thrusts, shear zones, and other low-angle ductile foliations) predominantly developed during Late Paleozoic and early Paleogene episodes of thrusting and folding.

Lateral-directional stability characteristics of a wing-fuselage configuration at angles of attack up to 44 deg

NASA Technical Reports Server (NTRS)

Henderson, W. P.; Huffman, J. K.

1974-01-01

An investigation has been conducted to determine the effects of configuration variables on the lateral-directional stability characteristics of a wing-fuselage configuration. The variables under study included variations in the location of a single center-line vertical tail and twin vertical tails, wing height, fuselage strakes, and horizontal tails. The study was conducted in the Langley high-speed 7-by 10-foot tunnel at a Mach number of 0.30, at angles of attack up to 44 deg and at sideslip angles of 0 deg and plus or minus 5 deg.

Variable angle spectroscopic ellipsometric characterization of HfO2 thin film

NASA Astrophysics Data System (ADS)

Kumar, M.; Kumari, N.; Karar, V.; Sharma, A. L.

2018-02-01

Hafnium Oxide film was deposited on BK7 glass substrate using reactive oxygenated E-Beam deposition technique. The film was deposited using in-situ quartz crystal thickness monitoring to control the film thickness and rate of evaporation. The thin film was grown with a rate of deposition of 0.3 nm/s. The coated substrate was optically characterized using spectrophotometer to determine its transmission spectra. The optical constants as well as film thickness of the hafnia film were extracted by variable angle spectroscopic ellipsometry with Cauchy fitting at incidence angles of 65˚, 70˚ and 75˚.

The influence of muscle pennation angle and cross-sectional area on contact forces in the ankle joint.

PubMed

Sopher, Ran S; Amis, Andrew A; Davies, D Ceri; Jeffers, Jonathan Rt

2017-01-01

Data about a muscle's fibre pennation angle and physiological cross-sectional area are used in musculoskeletal modelling to estimate muscle forces, which are used to calculate joint contact forces. For the leg, muscle architecture data are derived from studies that measured pennation angle at the muscle surface, but not deep within it. Musculoskeletal models developed to estimate joint contact loads have usually been based on the mean values of pennation angle and physiological cross-sectional area. Therefore, the first aim of this study was to investigate differences between superficial and deep pennation angles within each muscle acting over the ankle and predict how differences may influence muscle forces calculated in musculoskeletal modelling. The second aim was to investigate how inter-subject variability in physiological cross-sectional area and pennation angle affects calculated ankle contact forces. Eight cadaveric legs were dissected to excise the muscles acting over the ankle. The mean surface and deep pennation angles, fibre length and physiological cross-sectional area were measured. Cluster analysis was applied to group the muscles according to their architectural characteristics. A previously validated OpenSim model was used to estimate ankle muscle forces and contact loads using architecture data from all eight limbs. The mean surface pennation angle for soleus was significantly greater (54%) than the mean deep pennation angle. Cluster analysis revealed three groups of muscles with similar architecture and function: deep plantarflexors and peroneals, superficial plantarflexors and dorsiflexors. Peak ankle contact force was predicted to occur before toe-off, with magnitude greater than five times bodyweight. Inter-specimen variability in contact force was smallest at peak force. These findings will help improve the development of experimental and computational musculoskeletal models by providing data to estimate force based on both surface and deep pennation angles. Inter-subject variability in muscle architecture affected ankle muscle and contact loads only slightly. The link between muscle architecture and function contributes to the understanding of the relationship between muscle structure and function.

Cheaper Synthesis Of Multipole-Brushless-dc-Motor Current

NASA Technical Reports Server (NTRS)

Alhorn, Dean C.; Howard, David E.

1994-01-01

Circuit converts output of single two-phase shaft-angle resolver to that of multi-speed three-phase shaft-angle resolver. Converter circuit applicable to generation of multispeed, multiphase shaft-angle-resolver signals from single two-phase shaft-angle resolver. Combination of converter circuit and single two-phase shaft-angle resolver offer advantages in cost, weight, size, and complexity. Design readily adaptable to two-phase motor.

Suppression of threshold voltage variability in MOSFETs by adjustment of ion implantation parameters

NASA Astrophysics Data System (ADS)

Park, Jae Hyun; Chang, Tae-sig; Kim, Minsuk; Woo, Sola; Kim, Sangsig

2018-01-01

In this study, we investigate threshold voltage (VTH) variability of metal-oxide-semiconductor field-effect transistors induced by random dopant fluctuation (RDF). Our simulation work demonstrates not only the influence of the implantation parameters such as its dose, tilt angle, energy, and rotation angle on the RDF-induced VTH variability, but also the solution to reduce the effect of this variability. By adjusting the ion implantation parameters, the 3σ (VTH) is reduced from 43.8 mV to 28.9 mV. This 34% reduction is significant, considering that our technique is very cost effective and facilitates easy fabrication, increasing availability.

Dyke-sill relationships in Karoo dolerites as indicators of propagation and emplacement processes of mafic magmas in the shallow crust

NASA Astrophysics Data System (ADS)

Coetzee, A.; Kisters, A. F. M.

2017-04-01

This paper describes the spatial and temporal relationships between Karoo-age (ca. 180 Ma) dolerite dykes and a regional-scale saucer-sill complex from the Secunda (coal mine) Complex in the northeastern parts of the Karoo Basin of South Africa. Unlike parallel dyke swarms of regional extensional settings, mafic dykes commonly show curved geometries and highly variable orientations, short strike extents and complex cross-cutting and intersecting relationships. Importantly, the dyke networks originate from the upper contacts of the first-order dolerite sill-saucer structure and are not the feeders of the saucer complex. Cross-cutting relationships indicate the largely contemporaneous formation of dykes and the inner sill and inclined sheets of the underlying saucer. Systematic dykes form a distinct boxwork-type pattern of two high-angle, interconnected dyke sets. The formation and orientation of this dyke set is interpreted to be related to the stretching of roof strata above elongated magma lobes that facilitated the propagation of the inner sill, similar to the "cracked lid" model described for large saucer complexes in Antarctica. Dyke patterns generally reflect the saucer emplacement process and the associated deformation of wall rocks rather than far-field regional stresses.

Predictors of Frontal Plane Knee Moments During Side-Step Cutting to 45 and 110 Degrees in Men and Women: Implications for Anterior Cruciate Ligament Injury.

PubMed

Sigward, Susan M; Cesar, Guilherme M; Havens, Kathryn L

2015-11-01

To compare frontal plane knee moments, and kinematics and kinetics associated with knee valgus moments between cutting to 45 and 110 degrees, and to determine the predictive value of kinematics and ground reaction forces (GRFs) on knee valgus moments when cutting to these angles. Also, to determine whether sex differences exist in kinematics and kinetics when cutting to 45 and 110 degrees. Cross-sectional study. Laboratory setting. Forty-five (20 females) healthy young adult soccer athletes aged 16 to 23 years. Kinematic and kinetic variables were compared between randomly cued side-step cutting maneuvers to 45 and 110 degrees. Predictors of knee valgus moment were determined for each task. Kinematic variables: knee valgus angle, hip abduction, and internal rotation angles. Kinetic variables: vertical, posterior, and lateral GRFs, and knee valgus moment. Knee valgus moments were greater when cutting to 110 degrees compared with 45 degrees, and females exhibited greater moments than males. Vertical and lateral GRFs, hip internal rotation angle, and knee valgus angle explained 63% of the variance in knee valgus moment during cutting to 45 degrees. During cutting to 110 degrees, posterior GRF, hip internal rotation angle, and knee valgus angle explained 41% of the variance in knee valgus moment. Cutting tasks with larger redirection demands result in greater knee valgus moments. Similar factors, including shear GRFs, hip internal rotation, and knee valgus position contribute to knee valgus loading during cuts performed to smaller (45 degrees) and larger (110 degrees) angles. Reducing vertical and shear GRFs during cutting maneuvers may reduce knee valgus moments and thereby potentially reduce risk for anterior cruciate ligament injury.

T1 mapping with the variable flip angle technique: A simple correction for insufficient spoiling of transverse magnetization.

PubMed

Baudrexel, Simon; Nöth, Ulrike; Schüre, Jan-Rüdiger; Deichmann, Ralf

2018-06-01

The variable flip angle method derives T 1 maps from radiofrequency-spoiled gradient-echo data sets, acquired with different flip angles α. Because the method assumes validity of the Ernst equation, insufficient spoiling of transverse magnetization yields errors in T 1 estimation, depending on the chosen radiofrequency-spoiling phase increment (Δϕ). This paper presents a versatile correction method that uses modified flip angles α' to restore the validity of the Ernst equation. Spoiled gradient-echo signals were simulated for three commonly used phase increments Δϕ (50°/117°/150°), different values of α, repetition time (TR), T 1 , and a T 2 of 85 ms. For each parameter combination, α' (for which the Ernst equation yielded the same signal) and a correction factor C Δϕ (α, TR, T 1 ) = α'/α were determined. C Δϕ was found to be independent of T 1 and fitted as polynomial C Δϕ (α, TR), allowing to calculate α' for any protocol using this Δϕ. The accuracy of the correction method for T 2 values deviating from 85 ms was also determined. The method was tested in vitro and in vivo for variable flip angle scans with different acquisition parameters. The technique considerably improved the accuracy of variable flip angle-based T 1 maps in vitro and in vivo. The proposed method allows for a simple correction of insufficient spoiling in gradient-echo data. The required polynomial parameters are supplied for three common Δϕ. Magn Reson Med 79:3082-3092, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Comparative analysis of 2 glenoid version measurement methods in variable axial slices on 3-dimensionally reconstructed computed tomography scans.

PubMed

Cunningham, Gregory; Freebody, John; Smith, Margaret M; Taha, Mohy E; Young, Allan A; Cass, Benjamin; Giuffre, Bruno

2018-05-16

Most glenoid version measurement methods have been validated on 3-dimensionally corrected axial computed tomography (CT) slices at the mid glenoid. Variability of the vault according to slice height and angulation has not yet been studied and is crucial for proper surgical implant positioning. The aim of this study was to analyze the variation of the glenoid vault compared with the Friedman angle according to different CT slice heights and angulations. The hypothesis was that the Friedman angle would show less variability. Sixty shoulder CT scans were retrieved from a hospital imaging database and were reconstructed in the plane of the scapula. Seven axial slices of different heights and coronal angulations were selected, and measurements were carried out by 3 observers. Mid-glenoid mean version was -8.0° (±4.9°; range, -19.6° to +7.0°) and -2.1° (±4.7°; range, -13.0° to +10.3°) using the vault method and Friedman angle, respectively. For both methods, decreasing slice height or angulation did not significantly alter version. Increasing slice height or angulation significantly increased anteversion for the vault method (P < .001). Both interobserver reliability and intraobserver reliability were significantly higher using the Friedman angle. Version at the mid and lower glenoid is similar using either method. The vault method shows less reliability and more variability according to slice height or angulation. Yet, as it significantly differs from the Friedman angle, it should still be used in situations where maximum bone purchase is sought with glenoid implants. For any other situation, the Friedman angle remains the method of choice. Copyright © 2018 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Variability of Plyometric and Ballistic Exercise Technique Maintains Jump Performance.

PubMed

Chandler, Phillip T; Greig, Matthew; Comfort, Paul; McMahon, John J

2018-06-01

Chandler, PT, Greig, M, Comfort, P, and McMahon, JJ. Variability of plyometric and ballistic exercise technique maintains jump performance. J Strength Cond Res 32(6): 1571-1582, 2018-The aim of this study was to investigate changes in vertical jump technique over the course of a training session. Twelve plyometric and ballistic exercise-trained male athletes (age = 23.4 ± 4.6 years, body mass = 78.7 ± 18.8 kg, height = 177.1 ± 9.0 cm) performed 3 sets of 10 repetitions of drop jump (DJ), rebound jump (RJ) and squat jump (SJ). Each exercise was analyzed from touchdown to peak joint flexion and peak joint flexion to take-off. Squat jump was analyzed from peak joint flexion to take-off only. Jump height, flexion and extension time and range of motion, and instantaneous angles of the ankle, knee, and hip joints were measured. Separate 1-way repeated analyses of variance compared vertical jump technique across exercise sets and repetitions. Exercise set analysis found that SJ had lower results than DJ and RJ for the angle at peak joint flexion for the hip, knee, and ankle joints and take-off angle of the hip joint. Exercise repetition analysis found that the ankle joint had variable differences for the angle at take-off, flexion, and extension time for RJ. The knee joint had variable differences for flexion time for DJ and angle at take-off and touchdown for RJ. There was no difference in jump height. Variation in measured parameters across repetitions highlights variable technique across plyometric and ballistic exercises. This did not affect jump performance, but likely maintained jump performance by overcoming constraints (e.g., level of rate coding).

An X-ray study of the effect of the bite angle of chelating ligands on the geometry of palladium(allyl) complexes: implications for the regioselectivity in the allylic alkylation.

PubMed

van Haaren, R J; Goubitz, K; Fraanje, J; van Strijdonck, G P; Oevering, H; Coussens, B; Reek, J N; Kamer, P C; van Leeuwen, P W

2001-07-02

X-ray crystal structures of a series of cationic (P-P)palladium(1,1-(CH(3))(2)C(3)H(3)) complexes (P-P = dppe (1,2-bis(diphenylphosphino)ethane), dppf (1,1'-bis(diphenylphosphino)ferrocene), and DPEphos (2,2'-bis(diphenylphosphino)diphenyl ether)) and the (Xantphos)Pd(C(3)H(5))BF(4) (Xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene) complex have been determined. In the solid state structure, the phenyl rings of the ligand are oriented in the direction of the nonsymmetrically bound [1,1-(CH(3))(2)C(3)H(3)] moiety. An increase of the bite angle of the chelating ligand results in an increase of the cone angle. In complexes containing ligands having a large cone angle, the distances between the phenyl rings and the allyl moiety become small, resulting in a distortion of the symmetry of the palladium-allyl bond. In solution, two types of dynamic exchange have been observed, the pi-sigma rearrangement and the apparent rotation of the allyl moiety. At the same time, the folded structure of the ligand changes from an endo to an exo orientation or vice versa. The regioselectivity in the palladium-catalyzed allylic alkylation of 3-methyl-but-2-enyl acetate is determined by the cone angle of the bidentate phosphine ligand. Nucleophilic attack by a malonate anion takes place preferentially at the allylic carbon atom having the largest distance to palladium. Ligands with a larger cone angle direct the regioselectivity to the formation of the branched product, from 8% for dppe (1) to 61% found for Xantphos (6). The influence of the cone angle on the regioselectivity has been assigned to a sterically induced electronic effect.

UV-Vis reflection spectroscopy under variable angle incidence at the air-liquid interface.

PubMed

Roldán-Carmona, Cristina; Rubia-Payá, Carlos; Pérez-Morales, Marta; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

2014-03-07

The UV-Vis reflection spectroscopy (UV-Vis-RS) in situ at the air-liquid interface provides information about tilt and aggregation of chromophores in Langmuir monolayers. This information is particularly important given in most cases the chromophore is located at the polar region of the Langmuir monolayer. This region of the Langmuir monolayers has been hardly accessible by other experimental techniques. In spite of its enormous potential, the application of UV-Vis-RS has been limited mainly to reflection measurements under light normal incidence or at lower incidence angles than the Brewster angle. Remarkably, this technique is quite sensitive to the tilt of the chromophores at values of incidence angles close to or larger than the Brewster angle. Therefore, a novel method to obtain the order parameter of the chromophores at the air-liquid interface by using s- and p-polarized radiation at different incidence angles is proposed. This method allowed for the first time the experimental observation of the two components with different polarization properties of a single UV-Vis band at the air-liquid interface. The method of UV-Vis spectroscopy under variable angle incidence is presented as a new tool for obtaining rich detailed information on Langmuir monolayers.

Anterior Chamber Angle Shape Analysis and Classification of Glaucoma in SS-OCT Images.

PubMed

Ni Ni, Soe; Tian, J; Marziliano, Pina; Wong, Hong-Tym

2014-01-01

Optical coherence tomography is a high resolution, rapid, and noninvasive diagnostic tool for angle closure glaucoma. In this paper, we present a new strategy for the classification of the angle closure glaucoma using morphological shape analysis of the iridocorneal angle. The angle structure configuration is quantified by the following six features: (1) mean of the continuous measurement of the angle opening distance; (2) area of the trapezoidal profile of the iridocorneal angle centered at Schwalbe's line; (3) mean of the iris curvature from the extracted iris image; (4) complex shape descriptor, fractal dimension, to quantify the complexity, or changes of iridocorneal angle; (5) ellipticity moment shape descriptor; and (6) triangularity moment shape descriptor. Then, the fuzzy k nearest neighbor (fkNN) classifier is utilized for classification of angle closure glaucoma. Two hundred and sixty-four swept source optical coherence tomography (SS-OCT) images from 148 patients were analyzed in this study. From the experimental results, the fkNN reveals the best classification accuracy (99.11 ± 0.76%) and AUC (0.98 ± 0.012) with the combination of fractal dimension and biometric parameters. It showed that the proposed approach has promising potential to become a computer aided diagnostic tool for angle closure glaucoma (ACG) disease.

Quasi steady-state aerodynamic model development for race vehicle simulations

NASA Astrophysics Data System (ADS)

Mohrfeld-Halterman, J. A.; Uddin, M.

2016-01-01

Presented in this paper is a procedure to develop a high fidelity quasi steady-state aerodynamic model for use in race car vehicle dynamic simulations. Developed to fit quasi steady-state wind tunnel data, the aerodynamic model is regressed against three independent variables: front ground clearance, rear ride height, and yaw angle. An initial dual range model is presented and then further refined to reduce the model complexity while maintaining a high level of predictive accuracy. The model complexity reduction decreases the required amount of wind tunnel data thereby reducing wind tunnel testing time and cost. The quasi steady-state aerodynamic model for the pitch moment degree of freedom is systematically developed in this paper. This same procedure can be extended to the other five aerodynamic degrees of freedom to develop a complete six degree of freedom quasi steady-state aerodynamic model for any vehicle.

Running Technique is an Important Component of Running Economy and Performance

PubMed Central

FOLLAND, JONATHAN P.; ALLEN, SAM J.; BLACK, MATTHEW I.; HANDSAKER, JOSEPH C.; FORRESTER, STEPHANIE E.

2017-01-01

ABSTRACT Despite an intuitive relationship between technique and both running economy (RE) and performance, and the diverse techniques used by runners to achieve forward locomotion, the objective importance of overall technique and the key components therein remain to be elucidated. Purpose This study aimed to determine the relationship between individual and combined kinematic measures of technique with both RE and performance. Methods Ninety-seven endurance runners (47 females) of diverse competitive standards performed a discontinuous protocol of incremental treadmill running (4-min stages, 1-km·h−1 increments). Measurements included three-dimensional full-body kinematics, respiratory gases to determine energy cost, and velocity of lactate turn point. Five categories of kinematic measures (vertical oscillation, braking, posture, stride parameters, and lower limb angles) and locomotory energy cost (LEc) were averaged across 10–12 km·h−1 (the highest common velocity < velocity of lactate turn point). Performance was measured as season's best (SB) time converted to a sex-specific z-score. Results Numerous kinematic variables were correlated with RE and performance (LEc, 19 variables; SB time, 11 variables). Regression analysis found three variables (pelvis vertical oscillation during ground contact normalized to height, minimum knee joint angle during ground contact, and minimum horizontal pelvis velocity) explained 39% of LEc variability. In addition, four variables (minimum horizontal pelvis velocity, shank touchdown angle, duty factor, and trunk forward lean) combined to explain 31% of the variability in performance (SB time). Conclusions This study provides novel and robust evidence that technique explains a substantial proportion of the variance in RE and performance. We recommend that runners and coaches are attentive to specific aspects of stride parameters and lower limb angles in part to optimize pelvis movement, and ultimately enhance performance. PMID:28263283

Thin-film hermeticity - A quantitative analysis of diamondlike carbon using variable angle spectroscopic ellipsometry

NASA Technical Reports Server (NTRS)

Orzeszko, S.; De, Bhola N.; Woollam, John A.; Pouch, John J.; Alterovitz, Samuel A.

1988-01-01

This paper reports on the successful application of variable-angle spectroscopic ellipsometry to quantitative thin-film hermeticity evaluation. It is shown that, under a variety of film preparations and moisture introduction conditions, water penetrates only a very thin diamondlike carbon (DLC) top surface-roughness region. Thus, DLC is an excellent candidate for use as protective coatings in adverse chemical and aqueous environments.

ELECTRIC PHASE ANGLE OF CELL MEMBRANES

PubMed Central

Cole, Kenneth S.

1932-01-01

From the theory of an electric network containing any combination of resistances and a single variable impedance element having a constant phase angle independent of frequency, it is shown that the graph of the terminal series reactance against the resistance is an arc of a circle with the position of the center depending upon the phase angle of the variable element. If it be assumed that biological systems are equivalent to such a network, the hypotheses are supported at low and intermediate frequencies by data on red blood cells, muscle, nerve, and potato. For some tissues there is a marked divergence from the circle at high frequencies, which is not interpreted. PMID:19872673

Static internal performance of single-expansion-ramp nozzles with various combinations of internal geometric parameters

NASA Technical Reports Server (NTRS)

Re, R. J.; Leavitt, L. D.

1984-01-01

The effects of five geometric design parameters on the internal performance of single-expansion-ramp nozzles were investigated at nozzle pressure ratios up to 10 in the static-test facility of the Langley 16-Foot Transonic Tunnel. The geometric variables on the expansion-ramp surface of the upper flap consisted of ramp chordal angle, ramp length, and initial ramp angle. On the lower flap, the geometric variables consisted of flap angle and flap length. Both internal performance and static-pressure distributions on the centerlines of the upper and lower flaps were obtained for all 43 nozzle configurations tested.

The Viewing Geometry of Brown Dwarfs Influences Their Observed Colors and Variability Amplitudes

NASA Astrophysics Data System (ADS)

Vos, Johanna M.; Allers, Katelyn N.; Biller, Beth A.

2017-06-01

In this paper we study the full sample of known Spitzer [3.6 μm] and J-band variable brown dwarfs. We calculate the rotational velocities, v\\sin I, of 16 variable brown dwarfs using archival Keck NIRSPEC data and compute the inclination angles of 19 variable brown dwarfs. The results obtained show that all objects in the sample with mid-IR variability detections are inclined at an angle > 20^\\circ , while all objects in the sample displaying J-band variability have an inclination angle > 35^\\circ . J-band variability appears to be more affected by inclination than Spitzer [3.6 μm] variability, and is strongly attenuated at lower inclinations. Since J-band observations probe deeper into the atmosphere than mid-IR observations, this effect may be due to the increased atmospheric path length of J-band flux at lower inclinations. We find a statistically significant correlation between the color anomaly and inclination of our sample, where field objects viewed equator-on appear redder than objects viewed at lower inclinations. Considering the full sample of known variable L, T, and Y spectral type objects in the literature, we find that the variability properties of the two bands display notably different trends that are due to both intrinsic differences between bands and the sensitivity of ground-based versus space-based searches. However, in both bands we find that variability amplitude may reach a maximum at ˜7-9 hr periods. Finally, we find a strong correlation between color anomaly and variability amplitude for both the J-band and mid-IR variability detections, where redder objects display higher variability amplitudes.

An Improved Azimuth Angle Estimation Method with a Single Acoustic Vector Sensor Based on an Active Sonar Detection System.

PubMed

Zhao, Anbang; Ma, Lin; Ma, Xuefei; Hui, Juan

2017-02-20

In this paper, an improved azimuth angle estimation method with a single acoustic vector sensor (AVS) is proposed based on matched filtering theory. The proposed method is mainly applied in an active sonar detection system. According to the conventional passive method based on complex acoustic intensity measurement, the mathematical and physical model of this proposed method is described in detail. The computer simulation and lake experiments results indicate that this method can realize the azimuth angle estimation with high precision by using only a single AVS. Compared with the conventional method, the proposed method achieves better estimation performance. Moreover, the proposed method does not require complex operations in frequencydomain and achieves computational complexity reduction.

Design of a self-calibration high precision micro-angle deformation optical monitoring scheme

NASA Astrophysics Data System (ADS)

Gu, Yingying; Wang, Li; Guo, Shaogang; Wu, Yun; Liu, Da

2018-03-01

In order to meet the requirement of high precision and micro-angle measurement on orbit, a self-calibrated optical non-contact real-time monitoring device is designed. Within three meters, the micro-angle variable of target relative to measuring basis can be measured in real-time. The range of angle measurement is +/-50'', the angle measurement accuracy is less than 2''. The equipment can realize high precision real-time monitoring the micro-angle deformation, which caused by high strength vibration and shock of rock launching, sun radiation and heat conduction on orbit and so on.

Experimental investigation of a 0.15 scale model of a conformal variable-ramp inlet for the F-16 airplane

NASA Technical Reports Server (NTRS)

Hawkins, J. E.

1980-01-01

A 0.15 scale model of a proposed conformal variable-ramp inlet for the Multirole Fighter was tested from Mach 0.8 to 2.2 at a wide range of angles of attack and sideslip. Inlet ramp angle was varied to optimize ramp angle as a function of engine airflow, Mach number, angle of attack, and angle of sideslip. Several inlet configuration options were investigated to study their effects on inlet operation and to establish the final flight configuration. These variations were cowl sidewall cutback, cowl lip bluntness, boundary layer bleed, and first-ramp leading edge shape. Diagnostic and engine face instrumentation were used to evaluate inlet operation at various inlet stations and at the inlet/engine interface. Pressure recovery and stability of the inlet were satisfactory for the proposed application. On the basis of an engine stability audit of the worst-case instantaneous distortion patterns, no inlet/engine compatibility problems are expected for normal operations.

Determination of complex formation constants by phase sensitive alternating current polarography: Cadmium-polymethacrylic acid and cadmium-polygalacturonic acid.

PubMed

Garrigosa, Anna Maria; Gusmão, Rui; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

2007-10-15

The use of phase sensitive alternating current polarography (ACP) for the evaluation of complex formation constants of systems where electrodic adsorption is present has been proposed. The applicability of the technique implies the previous selection of the phase angle where contribution of capacitive current is minimized. This is made using Multivariate Curve Resolution by Alternating Least Squares (MCR-ALS) in the analysis of ACP measurements at different phase angles. The method is checked by the study of the complexation of Cd by polymethacrylic (PMA) and polygalacturonic (PGA) acids, and the optimal phase angles have been ca. -10 degrees for Cd-PMA and ca. -15 degrees for Cd-PGA systems. The goodness of phase sensitive ACP has been demonstrated comparing the determined complex formation constants with those obtained by reverse pulse polarography, a technique that minimizes the electrode adsorption effects on the measured currents.

Concerns about a variance approach to the X-ray diffractometric estimation of microfibril angle in wood

Treesearch

Steve P. Verrill; David E. Kretschmann; Victoria L. Herian; Michael Wiemann; Harry A. Alden

2010-01-01

In this paper we raise three technical concerns about Evans’s 1999 Appita Journal “variance approach” to estimating microfibril angle. The first concern is associated with the approximation of the variance of an X-ray intensity half-profile by a function of the microfibril angle and the natural variability of the microfibril angle, S2...

Manifold angles, the concept of self-similarity, and angle-enhanced bifurcation diagrams

PubMed Central

Beims, Marcus W.; Gallas, Jason A. C.

2016-01-01

Chaos and regularity are routinely discriminated by using Lyapunov exponents distilled from the norm of orthogonalized Lyapunov vectors, propagated during the temporal evolution of the dynamics. Such exponents are mean-field-like averages that, for each degree of freedom, squeeze the whole temporal evolution complexity into just a single number. However, Lyapunov vectors also contain a step-by-step record of what exactly happens with the angles between stable and unstable manifolds during the whole evolution, a big-data information permanently erased by repeated orthogonalizations. Here, we study changes of angles between invariant subspaces as observed during temporal evolution of Hénon’s system. Such angles are calculated numerically and analytically and used to characterize self-similarity of a chaotic attractor. In addition, we show how standard tools of dynamical systems may be angle-enhanced by dressing them with informations not difficult to extract. Such angle-enhanced tools reveal unexpected and practical facts that are described in detail. For instance, we present a video showing an angle-enhanced bifurcation diagram that exposes from several perspectives the complex geometrical features underlying the attractors. We believe such findings to be generic for extended classes of systems. PMID:26732416

Manifold angles, the concept of self-similarity, and angle-enhanced bifurcation diagrams

NASA Astrophysics Data System (ADS)

Beims, Marcus W.; Gallas, Jason A. C.

2016-01-01

Chaos and regularity are routinely discriminated by using Lyapunov exponents distilled from the norm of orthogonalized Lyapunov vectors, propagated during the temporal evolution of the dynamics. Such exponents are mean-field-like averages that, for each degree of freedom, squeeze the whole temporal evolution complexity into just a single number. However, Lyapunov vectors also contain a step-by-step record of what exactly happens with the angles between stable and unstable manifolds during the whole evolution, a big-data information permanently erased by repeated orthogonalizations. Here, we study changes of angles between invariant subspaces as observed during temporal evolution of Hénon’s system. Such angles are calculated numerically and analytically and used to characterize self-similarity of a chaotic attractor. In addition, we show how standard tools of dynamical systems may be angle-enhanced by dressing them with informations not difficult to extract. Such angle-enhanced tools reveal unexpected and practical facts that are described in detail. For instance, we present a video showing an angle-enhanced bifurcation diagram that exposes from several perspectives the complex geometrical features underlying the attractors. We believe such findings to be generic for extended classes of systems.

Guaranteed cost control with poles assignment for a flexible air-breathing hypersonic vehicle

NASA Astrophysics Data System (ADS)

Li, Hongyi; Si, Yulin; Wu, Ligang; Hu, Xiaoxiang; Gao, Huijun

2011-05-01

This article investigates the problem of guaranteed cost control for a flexible air-breathing hypersonic vehicle (FAHV). The FAHV includes intricate coupling between the engine and flight dynamics as well as complex interplay between flexible and rigid modes, which results in an intractable system for the control design. A longitudinal model is adopted for control design due to the complexity of the vehicle. First, for a highly nonlinear and coupled FAHV, a linearised model is established around the trim condition, which includes the state of altitude, velocity, angle of attack, pitch angle and pitch rate, etc. Secondly, by using the Lyapunov approach, performance analysis is carried out for the resulting closed-loop FAHV system, whose criterion with respect to guaranteed performance cost and poles assignment is expressed in the framework of linear matrix inequalities (LMIs). The established criterion exhibits a kind of decoupling between the Lyapunov positive-definite matrices to be determined and the FAHV system matrices, which is enabled by the introduction of additional slack matrix variables. Thirdly, a convex optimisation problem with LMI constraints is formulated for designing an admissible controller, which guarantees a prescribed performance cost with the simultaneous consideration of poles assignment for the resulting closed-loop system. Finally, some simulation results are provided to show that the guaranteed cost controller could assign the poles into the desired regional and achieve excellent reference altitude and velocity tracking performance.

Elastic scattering spectroscopy for detection of cancer risk in Barrett's esophagus: experimental and clinical validation of error removal by orthogonal subtraction for increasing accuracy

NASA Astrophysics Data System (ADS)

Zhu, Ying; Fearn, Tom; MacKenzie, Gary; Clark, Ben; Dunn, Jason M.; Bigio, Irving J.; Bown, Stephen G.; Lovat, Laurence B.

2009-07-01

Elastic scattering spectroscopy (ESS) may be used to detect high-grade dysplasia (HGD) or cancer in Barrett's esophagus (BE). When spectra are measured in vivo by a hand-held optical probe, variability among replicated spectra from the same site can hinder the development of a diagnostic model for cancer risk. An experiment was carried out on excised tissue to investigate how two potential sources of this variability, pressure and angle, influence spectral variability, and the results were compared with the variations observed in spectra collected in vivo from patients with Barrett's esophagus. A statistical method called error removal by orthogonal subtraction (EROS) was applied to model and remove this measurement variability, which accounted for 96.6% of the variation in the spectra, from the in vivo data. Its removal allowed the construction of a diagnostic model with specificity improved from 67% to 82% (with sensitivity fixed at 90%). The improvement was maintained in predictions on an independent in vivo data set. EROS works well as an effective pretreatment for Barrett's in vivo data by identifying measurement variability and ameliorating its effect. The procedure reduces the complexity and increases the accuracy and interpretability of the model for classification and detection of cancer risk in Barrett's esophagus.

Light refraction in sapphire plates with a variable angle of crystal optical axis to the surface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vetrov, V. N., E-mail: vasvetrov@mail.ru; Ignatenkov, B. A.

2013-05-15

The modification of sapphire by inhomogeneous plastic deformation makes it possible to obtain plates with a variable angle of inclination of the crystal optical axis to the plate surface. The refraction of light in this plate at perpendicular and oblique incidence of a parallel beam of rays is considered. The algorithm of calculating the refractive index of extraordinary ray and the birefringence is proposed.

Variable laser attenuator

DOEpatents

Foltyn, Stephen R.

1988-01-01

The disclosure relates to low loss, high power variable attenuators comprng one or more transmissive and/or reflective multilayer dielectric filters. The attenuator is particularly suitable to use with unpolarized lasers such as excimer lasers. Beam attenuation is a function of beam polarization and the angle of incidence between the beam and the filter and is controlled by adjusting the angle of incidence the beam makes to the filter or filters. Filters are selected in accordance with beam wavelength.

Computer Programs for the AUSEX (Aircraft Undersea Sound Experiment) Air-Water Acoustic Propagation Model.

DTIC Science & Technology

1976-01-28

source-receiver geometry dynamics. For a given time instant, each of the subroutines outputs time variables ( emission time, arrival time...transmission loss, depression/elevation and azimuthal arrival angles, received frequency and range variables (range at emission time, range at arrival time...with the wind equal 24.5 kts. In the double bottom bounce regions, the emission angles (at the virtual surface source) are moderately small (15

Analysis of Lower Body Kinematic and Kinetic: Differences Between Age and Handicap in Golfers of Various Ages and Skill Levels

NASA Astrophysics Data System (ADS)

Smilensky, Alexander

The purpose of this thesis was to provide a preliminary analysis of lower body golf swing biomechanics. Fourteen golfers of various ages and handicaps performed 10 swings off a tee with their driver. This study focused on a number of dependent variables including lead knee joint flexion angles, internal/external rotations, valgus/varus angles, as well as ground reaction forces normalized to body weight (%BW), X-Factor angle and club head velocity. Dependent variables were analyzed at four specifically defined events (start, initiation of downswing, contact and swing termination). Simple linear regressions were performed using age and handicap as independent variables to see if patterns could be determined at any of the events. No significant trends or results were reported within our sample. An analysis of variance (ANOVA) was then used to examine the effect of event on specific dependent variables. A number of differences were reported within each of the variables across the four events. This study hoped to provide a more comprehensive understanding of the movement patterns occurring at the lower body with special focus on the lead knee.

Variability between Clarke's angle and Chippaux-Smirak index for the diagnosis of flat feet

PubMed Central

Gonzalez-Martin, Cristina; Seoane-Pillado, Teresa; Lopez-Calviño, Beatriz; Pertega-Diaz, Sonia; Gil-Guillen, Vicente

2017-01-01

Abstract Background: The measurements used in diagnosing biomechanical pathologies vary greatly. The aim of this study was to determine the concordance between Clarke's angle and Chippaux-Smirak index, and to determine the validity of Clarke's angle using the Chippaux-Smirak index as a reference. Methods: Observational study in a random population sample (n= 1,002) in A Coruña (Spain). After informed patient consent and ethical review approval, a study was conducted of anthropometric variables, Charlson comorbidity score, and podiatric examination (Clarke's angle and Chippaux-Smirak index). Descriptive analysis and multivariate logistic regression were performed. Results: The prevalence of flat feet, using a podoscope, was 19.0% for the left foot and 18.9% for the right foot, increasing with age. The prevalence of flat feet according to the Chippaux-Smirak index or Clarke's angle increases significantly, reaching 62.0% and 29.7% respectively. The concordance (kappa I) between the indices according to age groups varied between 0.25-0.33 (left foot) and 0.21-0.30 (right foot). The intraclass correlation coefficient (ICC) between the Chippaux-Smirak index and Clarke's angle was -0.445 (left foot) and -0.424 (right foot). After adjusting for age, body mass index (BMI), comorbidity score and gender, the only variable with an independent effect to predict discordance was the BMI (OR= 0.969; 95% CI: 0.940-0.998). Conclusion: There is little concordance between the indices studied for the purpose of diagnosing foot arch pathologies. In turn, Clarke's angle has a limited sensitivity in diagnosing flat feet, using the Chippaux-Smirak index as a reference. This discordance decreases with higher BMI values. PMID:28559643

Variability between Clarke's angle and Chippaux-Smirak index for the diagnosis of flat feet.

PubMed

Gonzalez-Martin, Cristina; Pita-Fernandez, Salvador; Seoane-Pillado, Teresa; Lopez-Calviño, Beatriz; Pertega-Diaz, Sonia; Gil-Guillen, Vicente

2017-03-30

The measurements used in diagnosing biomechanical pathologies vary greatly. The aim of this study was to determine the concordance between Clarke's angle and Chippaux-Smirak index, and to determine the validity of Clarke's angle using the Chippaux-Smirak index as a reference. Observational study in a random population sample (n= 1,002) in A Coruña (Spain). After informed patient consent and ethical review approval, a study was conducted of anthropometric variables, Charlson comorbidity score, and podiatric examination (Clarke's angle and Chippaux-Smirak index). Descriptive analysis and multivariate logistic regression were performed. The prevalence of flat feet, using a podoscope, was 19.0% for the left foot and 18.9% for the right foot, increasing with age. The prevalence of flat feet according to the Chippaux-Smirak index or Clarke's angle increases significantly, reaching 62.0% and 29.7% respectively. The concordance (kappa I) between the indices according to age groups varied between 0.25-0.33 (left foot) and 0.21-0.30 (right foot). The intraclass correlation coefficient (ICC) between the Chippaux-Smirak index and Clarke's angle was -0.445 (left foot) and -0.424 (right foot). After adjusting for age, body mass index (BMI), comorbidity score and gender, the only variable with an independent effect to predict discordance was the BMI (OR= 0.969; 95% CI: 0.940-0.998). There is little concordance between the indices studied for the purpose of diagnosing foot arch pathologies. In turn, Clarke's angle has a limited sensitivity in diagnosing flat feet, using the Chippaux-Smirak index as a reference. This discordance decreases with higher BMI values.

Computer programs for calculation of sting pitch and roll angles required to obtain angles of attack and sideslip on wind tunnel models

NASA Technical Reports Server (NTRS)

Peterson, John B., Jr.

1988-01-01

Two programs have been developed to calculate the pitch and roll angles of a wind-tunnel sting drive system that will position a model at the desired angle of attack and and angle of sideslip in the wind tunnel. These programs account for the effects of sting offset angles, sting bending angles and wind-tunnel stream flow angles. In addition, the second program incorporates inputs from on-board accelerometers that measure model pitch and roll with respect to gravity. The programs are presented in the report and a description of the numerical operation of the programs with a definition of the variables used in the programs is given.

The complex phase gradient method applied to leaky Lamb waves.

PubMed

Lenoir, O; Conoir, J M; Izbicki, J L

2002-10-01

The classical phase gradient method applied to the characterization of the angular resonances of an immersed elastic plate, i.e., the angular poles of its reflection coefficient R, was proved to be efficient when their real parts are close to the real zeros of R and their imaginary parts are not too large compared to their real parts. This method consists of plotting the partial reflection coefficient phase derivative with respect to the sine of the incidence angle, considered as real, versus incidence angle. In the vicinity of a resonance, this curve exhibits a Breit-Wigner shape, whose minimum is located at the pole real part and whose amplitude is the inverse of its imaginary part. However, when the imaginary part is large, this method is not sufficiently accurate compared to the exact calculation of the complex angular root. An improvement of this method consists of plotting, in 3D, in the complex angle plane and at a given frequency, the angular phase derivative with respect to the real part of the sine of the incidence angle, considered as complex. When the angular pole is reached, the 3D curve shows a clear-cut transition whose position is easily obtained.

The influence of muscle pennation angle and cross-sectional area on contact forces in the ankle joint

PubMed Central

Sopher, Ran S; Amis, Andrew A; Davies, D Ceri; Jeffers, Jonathan RT

2016-01-01

Data about a muscle’s fibre pennation angle and physiological cross-sectional area are used in musculoskeletal modelling to estimate muscle forces, which are used to calculate joint contact forces. For the leg, muscle architecture data are derived from studies that measured pennation angle at the muscle surface, but not deep within it. Musculoskeletal models developed to estimate joint contact loads have usually been based on the mean values of pennation angle and physiological cross-sectional area. Therefore, the first aim of this study was to investigate differences between superficial and deep pennation angles within each muscle acting over the ankle and predict how differences may influence muscle forces calculated in musculoskeletal modelling. The second aim was to investigate how inter-subject variability in physiological cross-sectional area and pennation angle affects calculated ankle contact forces. Eight cadaveric legs were dissected to excise the muscles acting over the ankle. The mean surface and deep pennation angles, fibre length and physiological cross-sectional area were measured. Cluster analysis was applied to group the muscles according to their architectural characteristics. A previously validated OpenSim model was used to estimate ankle muscle forces and contact loads using architecture data from all eight limbs. The mean surface pennation angle for soleus was significantly greater (54%) than the mean deep pennation angle. Cluster analysis revealed three groups of muscles with similar architecture and function: deep plantarflexors and peroneals, superficial plantarflexors and dorsiflexors. Peak ankle contact force was predicted to occur before toe-off, with magnitude greater than five times bodyweight. Inter-specimen variability in contact force was smallest at peak force. These findings will help improve the development of experimental and computational musculoskeletal models by providing data to estimate force based on both surface and deep pennation angles. Inter-subject variability in muscle architecture affected ankle muscle and contact loads only slightly. The link between muscle architecture and function contributes to the understanding of the relationship between muscle structure and function. PMID:29805194

Optimal symmetric flight with an intermediate vehicle model

NASA Technical Reports Server (NTRS)

Menon, P. K. A.; Kelley, H. J.; Cliff, E. M.

1983-01-01

Optimal flight in the vertical plane with a vehicle model intermediate in complexity between the point-mass and energy models is studied. Flight-path angle takes on the role of a control variable. Range-open problems feature subarcs of vertical flight and singular subarcs. The class of altitude-speed-range-time optimization problems with fuel expenditure unspecified is investigated and some interesting phenomena uncovered. The maximum-lift-to-drag glide appears as part of the family, final-time-open, with appropriate initial and terminal transient exceeding level-flight drag, some members exhibiting oscillations. Oscillatory paths generally fail the Jacobi test for durations exceeding a period and furnish a minimum only for short-duration problems.

SU-E-T-325: The New Evaluation Method of the VMAT Plan Delivery Using Varian DynaLog Files and Modulation Complexity Score (MCS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tateoka, K; Graduate School of Medicine, Sapporo Medical University, Sapporo, JP; Fujimomo, K

2014-06-01

Purpose: The aim of the study is to evaluate the use of Varian DynaLog files to verify VMAT plans delivery and modulation complexity score (MCS) of VMAT. Methods: Delivery accuracy of machine performance was quantified by multileaf collimator (MLC) position errors, gantry angle errors and fluence delivery accuracy for volumetric modulated arc therapy (VMAT). The relationship between machine performance and plan complexity were also investigated using the modulation complexity score (MCS). Plan and Actual MLC positions, gantry angles and delivered fraction of monitor units were extracted from Varian DynaLog files. These factors were taken from the record and verify systemmore » of MLC control file. Planned and delivered beam data were compared to determine leaf position errors and gantry angle errors. Analysis was also performed on planned and actual fluence maps reconstructed from those of the DynaLog files. This analysis was performed for all treatment fractions of 5 prostate VMAT plans. The analysis of DynaLog files have been carried out by in-house programming in Visual C++. Results: The root mean square of leaf position and gantry angle errors were about 0.12 and 0.15, respectively. The Gamma of planned and actual fluence maps at 3%/3 mm criterion was about 99.21. The gamma of the leaf position errors were not directly related to plan complexity as determined by the MCS. Therefore, the gamma of the gantry angle errors were directly related to plan complexity as determined by the MCS. Conclusion: This study shows Varian dynalog files for VMAT plan can be diagnosed delivery errors not possible with phantom based quality assurance. Furthermore, the MCS of VMAT plan can evaluate delivery accuracy for patients receiving of VMAT. Machine performance was found to be directly related to plan complexity but this is not the dominant determinant of delivery accuracy.« less

Experimental Study of an Axisymmetric Dual Throat Fluidic Thrust Vectoring Nozzle for Supersonic Aircraft Application

NASA Technical Reports Server (NTRS)

Flamm, Jeffrey D.; Deere, Karen A.; Mason, Mary L.; Berrier, Bobby L.; Johnson, Stuart K.

2007-01-01

An axisymmetric version of the Dual Throat Nozzle concept with a variable expansion ratio has been studied to determine the impacts on thrust vectoring and nozzle performance. The nozzle design, applicable to a supersonic aircraft, was guided using the unsteady Reynolds-averaged Navier-Stokes computational fluid dynamics code, PAB3D. The axisymmetric Dual Throat Nozzle concept was tested statically in the Jet Exit Test Facility at the NASA Langley Research Center. The nozzle geometric design variables included circumferential span of injection, cavity length, cavity convergence angle, and nozzle expansion ratio for conditions corresponding to take-off and landing, mid climb and cruise. Internal nozzle performance and thrust vectoring performance was determined for nozzle pressure ratios up to 10 with secondary injection rates up to 10 percent of the primary flow rate. The 60 degree span of injection generally performed better than the 90 degree span of injection using an equivalent injection area and number of holes, in agreement with computational results. For injection rates less than 7 percent, thrust vector angle for the 60 degree span of injection was 1.5 to 2 degrees higher than the 90 degree span of injection. Decreasing cavity length improved thrust ratio and discharge coefficient, but decreased thrust vector angle and thrust vectoring efficiency. Increasing cavity convergence angle from 20 to 30 degrees increased thrust vector angle by 1 degree over the range of injection rates tested, but adversely affected system thrust ratio and discharge coefficient. The dual throat nozzle concept generated the best thrust vectoring performance with an expansion ratio of 1.0 (a cavity in between two equal minimum areas). The variable expansion ratio geometry did not provide the expected improvements in discharge coefficient and system thrust ratio throughout the flight envelope of typical a supersonic aircraft. At mid-climb and cruise conditions, the variable geometry design compromised thrust vector angle achieved, but some thrust vector control would be available, potentially for aircraft trim. The fixed area, expansion ratio of 1.0, Dual Throat Nozzle provided the best overall compromise for thrust vectoring and nozzle internal performance over the range of NPR tested compared to the variable geometry Dual Throat Nozzle.

An Improved Azimuth Angle Estimation Method with a Single Acoustic Vector Sensor Based on an Active Sonar Detection System

PubMed Central

Zhao, Anbang; Ma, Lin; Ma, Xuefei; Hui, Juan

2017-01-01

In this paper, an improved azimuth angle estimation method with a single acoustic vector sensor (AVS) is proposed based on matched filtering theory. The proposed method is mainly applied in an active sonar detection system. According to the conventional passive method based on complex acoustic intensity measurement, the mathematical and physical model of this proposed method is described in detail. The computer simulation and lake experiments results indicate that this method can realize the azimuth angle estimation with high precision by using only a single AVS. Compared with the conventional method, the proposed method achieves better estimation performance. Moreover, the proposed method does not require complex operations in frequency-domain and achieves computational complexity reduction. PMID:28230763

Real time selective harmonic minimization for multilevel inverters using genetic algorithm and artifical neural network angle generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filho, Faete J; Tolbert, Leon M; Ozpineci, Burak

2012-01-01

The work developed here proposes a methodology for calculating switching angles for varying DC sources in a multilevel cascaded H-bridges converter. In this approach the required fundamental is achieved, the lower harmonics are minimized, and the system can be implemented in real time with low memory requirements. Genetic algorithm (GA) is the stochastic search method to find the solution for the set of equations where the input voltages are the known variables and the switching angles are the unknown variables. With the dataset generated by GA, an artificial neural network (ANN) is trained to store the solutions without excessive memorymore » storage requirements. This trained ANN then senses the voltage of each cell and produces the switching angles in order to regulate the fundamental at 120 V and eliminate or minimize the low order harmonics while operating in real time.« less

Complex-valued Multidirectional Associative Memory

NASA Astrophysics Data System (ADS)

Kobayashi, Masaki; Yamazaki, Haruaki

Hopfield model is a representative associative memory. It was improved to Bidirectional Associative Memory(BAM) by Kosko and Multidirectional Associative Memory(MAM) by Hagiwara. They have two layers or multilayers. Since they have symmetric connections between layers, they ensure to converge. MAM can deal with multiples of many patterns, such as (x1, x2,…), where xm is the pattern on layer-m. Noest, Hirose and Nemoto proposed complex-valued Hopfield model. Lee proposed complex-valued Bidirectional Associative Memory. Zemel proved the rotation invariance of complex-valued Hopfield model. It means that the rotated pattern also stored. In this paper, the complex-valued Multidirectional Associative Memory is proposed. The rotation invariance is also proved. Moreover it is shown by computer simulation that the differences of angles of given patterns are automatically reduced. At first we define complex-valued Multidirectional Associative Memory. Then we define the energy function of network. By using energy function, we prove that the network ensures to converge. Next, we define the learning law and show the characteristic of recall process. The characteristic means that the differences of angles of given patterns are automatically reduced. Especially we prove the following theorem. In case that only a multiple of patterns is stored, if patterns with different angles are given to each layer, the differences are automatically reduced. Finally, we invest that the differences of angles influence the noise robustness. It reduce the noise robustness, because input to each layer become small. We show that by computer simulations.

Variable laser attenuator

DOEpatents

Foltyn, S.R.

1987-05-29

The disclosure relates to low loss, high power variable attenuators comprising one or more transmissive and/or reflective multilayer dielectric filters. The attenuator is particularly suitable to use with unpolarized lasers such as excimer lasers. Beam attenuation is a function of beam polarization and the angle of incidence between the beam and the filter and is controlled by adjusting the angle of incidence the beam makes to the filter or filters. Filters are selected in accordance with beam wavelength. 9 figs.

Contact Hamiltonian systems and complete integrability

NASA Astrophysics Data System (ADS)

Visinescu, Mihai

2017-12-01

We summarize recent results on the integrability of Hamiltonian systems on contact manifolds. We explain how to extend the classical formulation of action-angle variables to contact integrable systems. Using the Jacobi brackets defined on contact manifolds, we discuss the commutativity of first integrals for contact Hamiltonian systems and present the construction of generalized contact action-angle variables. We illustrate the integrability in the contact geometry on the five-dimensional Sasaki-Einstein spaces T1,1 and Yp,q.

Imaging and Variability Studies of CTA 102 during the 2016 January γ-ray Flare

NASA Astrophysics Data System (ADS)

Li, Xiaofeng; Mohan, P.; An, T.; Hong, Xiaoyu; Cheng, Xiaopeng; Yang, Jun; Zhang, Yingkang; Zhang, Zhongli; Zhao, Wei

2018-02-01

The γ-ray-bright blazar CTA 102 is studied using imaging (new 15 GHz and archival 43 GHz Very Long Baseline Array, VLBA data) and time variable optical flux density, polarization degree, and electric vector position angle (EVPA) spanning between 2015 June 1 and 2016 October 1, covering a prominent γ-ray flare during 2016 January. The pc-scale jet indicates expansion with oscillatory features up to 17 mas. Component proper motions are in the range 0.04–0.33 mas yr‑1 with acceleration up to 1.2 mas followed by a slowing down beyond 1.5 mas. A jet bulk Lorentz factor ≥17.5, position angle of 128.°3, inclination angle ≤6.°6 and intrinsic half opening angle ≤1.°8 are derived from the VLBA data. These inferences are employed in a helical jet model to infer long-term variability in flux density, polarization degree, EVPA, and a rotation of the Stokes Q and U parameters. A core distance of r core,43 GHz = 22.9 pc, and a magnetic field strength at 1 pc and the core location of 1.57 G and 0.07 G, respectively, are inferred using the core-shift method. The study is useful in the context of estimating jet parameters and in offering clues to distinguish mechanisms responsible for variability over different timescales.

Shoulder pain and time dependent structure in wheelchair propulsion variability

PubMed Central

Jayaraman, Chandrasekaran; Moon, Yaejin; Sosnoff, Jacob J.

2016-01-01

Manual wheelchair propulsion places considerable repetitive mechanical strain on the upper limbs leading to shoulder injury and pain. While recent research indicates that the amount of variability in wheelchair propulsion and shoulder pain may be related. There has been minimal inquiry into the fluctuation over time (i.e. time-dependent structure) in wheelchair propulsion variability. Consequently the purpose of this investigation was to examine if the time-dependent structure in the wheelchair propulsion parameters are related to shoulder pain. 27 experienced wheelchair users manually propelled their own wheelchair fitted with a SMARTWheel on a roller at 1.1 m/s for 3 minutes. Time-dependent structure of cycle-to-cycle fluctuations in contact angle and inter push time interval was quantified using sample entropy (SampEn) and compared between the groups with/without shoulder pain using non-parametric statistics. Overall findings were, (1) variability observed in contact angle fluctuations during manual wheelchair propulsion is structured (Z=3.15;p<0.05), (2) individuals with shoulder pain exhibited higher SampEn magnitude for contact angle during wheelchair propulsion than those without pain (χ2(1)=6.12;p<0.05); and (3) SampEn of contact angle correlated significantly with self-reported shoulder pain (rs (WUSPI) =0.41;rs (VAS)=0.56;p<0.05). It was concluded that the time-dependent structure in wheelchair propulsion may provide novel information for tracking and monitoring shoulder pain. PMID:27134151

Molecular counting by photobleaching in protein complexes with many subunits: best practices and application to the cellulose synthesis complex

PubMed Central

Chen, Yalei; Deffenbaugh, Nathan C.; Anderson, Charles T.; Hancock, William O.

2014-01-01

The constituents of large, multisubunit protein complexes dictate their functions in cells, but determining their precise molecular makeup in vivo is challenging. One example of such a complex is the cellulose synthesis complex (CSC), which in plants synthesizes cellulose, the most abundant biopolymer on Earth. In growing plant cells, CSCs exist in the plasma membrane as six-lobed rosettes that contain at least three different cellulose synthase (CESA) isoforms, but the number and stoichiometry of CESAs in each CSC are unknown. To begin to address this question, we performed quantitative photobleaching of GFP-tagged AtCESA3-containing particles in living Arabidopsis thaliana cells using variable-angle epifluorescence microscopy and developed a set of information-based step detection procedures to estimate the number of GFP molecules in each particle. The step detection algorithms account for changes in signal variance due to changing numbers of fluorophores, and the subsequent analysis avoids common problems associated with fitting multiple Gaussian functions to binned histogram data. The analysis indicates that at least 10 GFP-AtCESA3 molecules can exist in each particle. These procedures can be applied to photobleaching data for any protein complex with large numbers of fluorescently tagged subunits, providing a new analytical tool with which to probe complex composition and stoichiometry. PMID:25232006

Molecular counting by photobleaching in protein complexes with many subunits: best practices and application to the cellulose synthesis complex

DOE PAGES

Chen, Yalei; Deffenbaugh, Nathan C.; Anderson, Charles T.; ...

2014-09-17

The constituents of large, multisubunit protein complexes dictate their functions in cells, but determining their precise molecular makeup in vivo is challenging. One example of such a complex is the cellulose synthesis complex (CSC), which in plants synthesizes cellulose, the most abundant biopolymer on Earth. In growing plant cells, CSCs exist in the plasma membrane as six-lobed rosettes that contain at least three different cellulose synthase (CESA) isoforms, but the number and stoichiometry of CESAs in each CSC are unknown. To begin to address this question, we performed quantitative photobleaching of GFP-tagged AtCESA3-containing particles in living Arabidopsis thaliana cells usingmore » variable-angle epifluorescence microscopy and developed a set of information-based step detection procedures to estimate the number of GFP molecules in each particle. The step detection algorithms account for changes in signal variance due to changing numbers of fluorophores, and the subsequent analysis avoids common problems associated with fitting multiple Gaussian functions to binned histogram data. The analysis indicates that at least 10 GFP-AtCESA3 molecules can exist in each particle. In conclusion, these procedures can be applied to photobleaching data for any protein complex with large numbers of fluorescently tagged subunits, providing a new analytical tool with which to probe complex composition and stoichiometry.« less

Commande de vol non lineaire d'un drone a voilure fixe par la methode du backstepping

NASA Astrophysics Data System (ADS)

Finoki, Edouard

This thesis describes the design of a non-linear controller for a UAV using the backstepping method. It is a fixed-wing UAV, the NexSTAR ARF from HobbicoRTM. The aim is to find the expressions of the aileron, the elevator, and the rudder deflection in order to command the flight path angle, the heading angle and the sideslip angle. Controlling the flight path angle allows a steady, climb or descent flight, controlling the heading cap allows to choose the heading and annul the sideslip angle allows an efficient flight. A good technical control has to ensure the stability of the system and provide optimal performances. Backstepping interlaces the choice of a Lyapunov function with the design of feedback control. This control technique works with the true non-linear model without any approximation. The procedure is to transform intermediate state variables into virtual inputs which will control other state variables. Advantages of this technique are its recursivity, its minimum control effort and its cascaded structure that allows dividing a high order system into several simpler lower order systems. To design this non-linear controller, a non-linear model of the UAV was used. Equations of motion are very accurate, aerodynamic coefficients result from interpolations between several essential variables in flight. The controller has been implemented in Matlab/Simulink and FlightGear.

Low-speed aerodynamic test of an axisymmetric supersonic inlet with variable cowl slot

NASA Technical Reports Server (NTRS)

Powell, A. G.; Welge, H. R.; Trefny, C. J.

1985-01-01

The experimental low-speed aerodynamic characteristics of an axisymmetric mixed-compression supersonic inlet with variable cowl slot are described. The model consisted of the NASA P-inlet centerbody and redesigned cowl with variable cowl slot powered by the JT8D single-stage fan simulator and driven by an air turbine. The model was tested in the NASA Lewis Research Center 9- by 15-foot low-speed tunnel at Mach numbers of 0, 0.1, and 0.2 over a range of flows, cowl slot openings, centerbody positions, and angles of attack. The variable cowl slot was effective in minimizing lip separation at high velocity ratios, showed good steady-state and dynamic distortion characteristics, and had good angle-of-attack tolerance.

Vibration and buckling of rotating, pretwisted, preconed beams including Coriolis effects

NASA Technical Reports Server (NTRS)

Subrahmanyam, K. B.; Kaza, K. R. V.

1985-01-01

The effects of pretwist, precone, setting angle and Coriolis forces on the vibration and buckling behavior of rotating, torsionally rigid, cantilevered beams were studied. The beam is considered to be clamped on the axis of rotation in one case, and off the axis of rotation in the other. Two methods are employed for the solution of the vibration problem: (1) one based upon a finite-difference approach using second order central differences for solution of the equations of motion, and (2) based upon the minimum of the total potential energy functional with a Ritz type of solution procedure making use of complex forms of shape functions for the dependent variables. The individual and collective effects of pretwist, precone, setting angle, thickness ratio and Coriolis forces on the natural frequencies and the buckling boundaries are presented. It is shown that the inclusion of Coriolis effects is necessary for blades of moderate to large thickness ratios while these effects are not so important for small thickness ratio blades. The possibility of buckling due to centrifugal softening terms for large values of precone and rotation is shown.

Vibration and buckling of rotating, pretwisted, preconed beams including Cooriolis effects

NASA Technical Reports Server (NTRS)

Subrahmanyam, K. B.; Kaza, K. R. V.

1985-01-01

The effects of pretwist, precone, setting angle and Coriolis forces on the vibration and buckling behavior of rotating, torsionally rigid, cantilevered beams were studied. The beam is considered to be clamped on the axis of rotation in one case, and off the axis of rotation in the other. Two methods are employed for the solution of the vibration problem: (1) one based upon a finite-difference approach using second order central differences for solution of the equations of motion, and (2) based upon the minimum of the total potential energy functional with a Ritz type of solution procedure making use of complex forms of shape functions for the dependent variables. The individual and collective effects of pretwist, precone, setting angle, thickness ratio and Coriolis forces on the natural frequencies and the buckling boundaries are presented. It is shown that the inclusion of Coriolis effects is necessary for blades of moderate to large thickness ratios while these effects are not so important for small thickness ratio blades. The possibility of buckling due to centrifugal softening terms for large values of precone and rotation is shown.

Influence of tooth profile on the noncircular gear tooth contact

NASA Astrophysics Data System (ADS)

Cristescu, A.; Andrei, L.; Cristescu, B.

2017-02-01

With noncircular gears, the continuous modification of the tooth meshing, in terms of variation of the tooth profiles and the line of action position and inclination, makes difficult the implementation of a general standard procedure for the analysis of the noncircular gears tooth contact. In this paper, the authors present a graphical approach that enables the tooth contact static pattern to be produced and evaluated in case of a noncircular gear with complex geometry of the pitch curve. The study is virtually developed, in AutoCAD environment, by animating and investigating the gear solid models in mesh. The tooth static contact analysis enables the path of contact area and distribution to be evaluated in correlation with the following variable initial data: gear pitch curve geometry, tooth profile geometry, as a consequence of different generating procedures, and the gear pressure angle. It was found out that the noncircular gear tooth contact could be improved by choosing different procedures for the tooth flank generation in concave and convex zones and by increasing the gear pressure angle.

A fully relativistic twisted disc around a slowly rotating Kerr black hole: derivation of dynamical equations and the shape of stationary configurations

NASA Astrophysics Data System (ADS)

Zhuravlev, V. V.; Ivanov, P. B.

2011-08-01

In this paper we derive equations describing the dynamics and stationary configurations of a twisted fully relativistic thin accretion disc around a slowly rotating black hole. We assume that the inclination angle of the disc is small and that the standard relativistic generalization of the α model of accretion discs is valid when the disc is flat. We find that similar to the case of non-relativistic twisted discs the disc dynamics and stationary shapes can be determined by a pair of equations formulated for two complex variables describing the orientation of the disc rings and velocity perturbations induced by the twist. We analyse analytically and numerically the shapes of stationary twisted configurations of accretion discs having non-zero inclinations with respect to the black hole equatorial plane at large distances r from the black hole. It is shown that the stationary configurations depend on two parameters - the viscosity parameter α and the parameter ?, where δ* is the opening angle (δ*˜h/r, where h is the disc half-thickness and r is large) of a flat disc and a is the black hole rotational parameter. When a > 0 and ? the shapes depend drastically on the value of α. When α is small the disc inclination angle oscillates with radius with amplitude and radial frequency of the oscillations dramatically increasing towards the last stable orbit, Rms. When α has a moderately small value the oscillations do not take place but the disc does not align with the equatorial plane at small radii. The disc inclination angle either is increasing towards Rms or exhibits a non-monotonic dependence on the radial coordinate. Finally, when α is sufficiently large the disc aligns with the equatorial plane at small radii. When a < 0 the disc aligns with the equatorial plane for all values of α. The results reported here may have implications for determining the structure and variability of accretion discs close to Rms as well as for modelling of emission spectra coming from different sources, which are supposed to contain black holes.

Bioelectrical impedance phase angle relates to function, disease severity and prognosis in stable chronic obstructive pulmonary disease.

PubMed

Maddocks, Matthew; Kon, Samantha S C; Jones, Sarah E; Canavan, Jane L; Nolan, Claire M; Higginson, Irene J; Gao, Wei; Polkey, Michael I; Man, William D-C

2015-12-01

Bioelectrical impedance analysis (BIA) provides a simple method to assess changes in body composition. Raw BIA variables such as phase angle provide direct information on cellular mass and integrity, without the assumptions inherent in estimating body compartments, e.g. fat-free mass (FFM). Phase angle is a strong functional and prognostic marker in many disease states, but data in COPD are lacking. Our aims were to describe the measurement of phase angle in patients with stable COPD and determine the construct and discriminate validity of phase angle by assessing its relationship with established markers of function, disease severity and prognosis. 502 outpatients with stable COPD were studied. Phase angle and FFM by BIA, quadriceps strength (QMVC), 4-m gait speed (4MGS), 5 sit-to-stand time (5STS), incremental shuttle walk (ISW), and composite prognostic indices (ADO, iBODE) were measured. Patients were stratified into normal and low phase angle and FFM index. Phase angle correlated positively with FFM and functional outcomes (r = 0.35-0.66, p < 0.001) and negatively with prognostic indices (r = -0.35 to -0.48, p < 0.001). In regression models, phase angle was independently associated with ISW, ADO and iBODE whereas FFM was removed. One hundred and seventy patients (33.9% [95% CI, 29.9-38.1]) had a low phase angle. Phenotypic characteristics included lower QMVC, ISW, and 4MGS, higher 5STS, ADO and iBODE scores, and more exacerbations and hospital days in past year. The proportion of patients to have died was significantly higher in patients with low phase angle compared to those with normal phase angle (8.2% versus 3.6%, p = 0.02). Phase angle relates to markers of function, disease severity and prognosis in patients with COPD. As a directly measured variable, phase angle offers more useful information than fat-free mass indices. Copyright © 2015 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Monte Carlo-based assessment of the trade-off between spatial resolution, field-of-view and scattered radiation in the variable resolution X-ray CT scanner.

PubMed

Arabi, Hossein; Kamali Asl, Ali Reza; Ay, Mohammad Reza; Zaidi, Habib

2015-07-01

The purpose of this work is to evaluate the impact of optimization of magnification on performance parameters of the variable resolution X-ray (VRX) CT scanner. A realistic model based on an actual VRX CT scanner was implemented in the GATE Monte Carlo simulation platform. To evaluate the influence of system magnification, spatial resolution, field-of-view (FOV) and scatter-to-primary ratio of the scanner were estimated for both fixed and optimum object magnification at each detector rotation angle. Comparison and inference between these performance parameters were performed angle by angle to determine appropriate object position at each opening half angle. Optimization of magnification resulted in a trade-off between spatial resolution and FOV of the scanner at opening half angles of 90°-12°, where the spatial resolution increased up to 50% and the scatter-to-primary ratio decreased from 4.8% to 3.8% at a detector angle of about 90° for the same FOV and X-ray energy spectrum. The disadvantage of magnification optimization at these angles is the significant reduction of the FOV (up to 50%). Moreover, magnification optimization was definitely beneficial for opening half angles below 12° improving the spatial resolution from 7.5 cy/mm to 20 cy/mm. Meanwhile, the FOV increased by more than 50% at these angles. It can be concluded that optimization of magnification is essential for opening half angles below 12°. For opening half angles between 90° and 12°, the VRX CT scanner magnification should be set according to the desired spatial resolution and FOV. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Identification and Modelling of the In-Plane Reinforcement Orientation Variations in a CFRP Laminate Produced by Manual Lay-Up

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2017-08-01

Reinforcement angle orientation has a significant effect on the mechanical properties of composite materials. This work presents a methodology to introduce variable reinforcement angles into finite element (FE) models of composite structures. The study of reinforcement orientation variations uses meta-models to identify and control a continuous variation across the composite ply. First, the reinforcement angle is measured through image analysis techniques of the composite plies during the lay-up phase. Image analysis results show that variations in the mean ply orientations are between -0.5 and 0.5° with standard deviations ranging between 0.34 and 0.41°. An automatic post-treatment of the images determines the global and local angle variations yielding good agreements visually and numerically between the analysed images and the identified parameters. A composite plate analysed at the end of the cooling phase is presented as a case of study. Here, the variation in residual strains induced by the variability in the reinforcement orientation are up to 28% of the strain field of the homogeneous FE model. The proposed methodology has shown its capabilities to introduce material and geometrical variability into FE analysis of layered composite structures.

Identification and Modelling of the In-Plane Reinforcement Orientation Variations in a CFRP Laminate Produced by Manual Lay-Up

NASA Astrophysics Data System (ADS)

Davila, Yves; Crouzeix, Laurent; Douchin, Bernard; Collombet, Francis; Grunevald, Yves-Henri

2018-06-01

Reinforcement angle orientation has a significant effect on the mechanical properties of composite materials. This work presents a methodology to introduce variable reinforcement angles into finite element (FE) models of composite structures. The study of reinforcement orientation variations uses meta-models to identify and control a continuous variation across the composite ply. First, the reinforcement angle is measured through image analysis techniques of the composite plies during the lay-up phase. Image analysis results show that variations in the mean ply orientations are between -0.5 and 0.5° with standard deviations ranging between 0.34 and 0.41°. An automatic post-treatment of the images determines the global and local angle variations yielding good agreements visually and numerically between the analysed images and the identified parameters. A composite plate analysed at the end of the cooling phase is presented as a case of study. Here, the variation in residual strains induced by the variability in the reinforcement orientation are up to 28% of the strain field of the homogeneous FE model. The proposed methodology has shown its capabilities to introduce material and geometrical variability into FE analysis of layered composite structures.

Influence of magnification and superimposition of structures on cephalometric diagnosis.

PubMed

Paula, Leonardo Koerich de; Solon-de-Mello, Priscilla de Almeida; Mattos, Claudia Trindade; Ruellas, Antônio Carlos de Oliveira; Sant'Anna, Eduardo Franzotti

2015-01-01

The purpose of this study was to assess the influence of magnification and superimposition of structures on CBCT-generated lateral cephalometric radiographs (LCR) using different segments of the cranium. CBCT scans of 10 patients were selected. Four LCR were generated using Dolphin Imaging(r) software: full-face, right side, left side and center of the head. A total of 40 images were imported into Radiocef Studio 2(r), and the angles of the most common cephalometric analyses were traced by the same observer twice and within a 10-day interval. Statistical analyses included intraexaminer agreement and comparison between methods by means of intraclass correlation coefficient (ICC) and Bland-Altman agreement tests. Intraexaminer agreement of the angles assessed by ICC was excellent (> 0.90) for 83% of measurements, good (between 0.75 and 0.90) for 15%, and moderate (between 0.50 and 0.75) for 2% of measurements. The comparison between methods by ICC was excellent for 68% of measurements, good for 26%, and moderate for 6%. Variables presenting wider confidence intervals (> 6o) in the Bland-Altman tests, in intraexaminer assessment, were: mandibular incisor angle, maxillary incisor angle, and occlusal plane angle. And in comparison methods the variables with wider confidence interval were: mandibular incisor, maxillary incisor, GoGn, occlusal plane angle, Frankfort horizontal plane (FHP), and CoA. Superimposition of structures seemed to influence the results more than magnification, and neither one of them significantly influenced the measurements. Considerable individual variability may occur, especially for mandibular and maxillary incisors, FHP and occlusal plane.

Comparison of tunnel variability between trans-portal and outside-in techniques in ACL reconstruction.

PubMed

Sim, Jae-Ang; Kim, Jong-Min; Lee, Sahnghoon; Bae, Ji-Yong; Seon, Jong-Keun

2017-04-01

Although trans-portal and outside-in techniques are commonly used for anatomical ACL reconstruction, there is very little information on variability in tunnel placement between two techniques. A total of 103 patients who received ACL reconstruction using trans-portal (50 patients) and outside-in techniques (53 patients) were included in the study. The ACL tunnel location, length and graft-femoral tunnel angle were analyzed using the 3D CT knee models, and we compared the location and length of the femoral and tibial tunnels, and graft bending angle between the two techniques. The variability in each technique regarding the tunnel location, length and graft tunnel angle using the range values was also compared. There were no differences in the average of femoral tunnel depth and height between the two groups. The ranges of femoral tunnel depth and height showed no difference between two groups (36 and 41 % in trans-portal technique vs. 32 and 41 % in outside-in technique). The average value and ranges of tibial tunnel location also showed similar results in two groups. The outside-in technique showed longer femoral tunnel than the trans-portal technique (34.0 vs. 36.8 mm, p = 0.001). The range of femoral tunnel was also wider in trans-portal technique than in outside-in technique. Although the outside-in technique showed significant acute graft bending angle than trans-portal technique in average values, the trans-portal technique showed wider ranges in graft bending angle than outside-in technique [ranges 73° (SD 13.6) vs. 53° (SD 10.7), respectively]. Although both trans-portal and outside-in techniques in ACL reconstruction can provide relatively consistent in femoral and tibial tunnel locations, trans-portal technique showed high variability in femoral tunnel length and graft bending angles than outside-in technique. Therefore, the outside-in technique in ACL reconstruction is considered as the effective method for surgeons to make more consistent femoral tunnel. III.

Ergonomic evaluation of interior design of Shoka vehicle and proposing recommendations for improvement.

PubMed

Mazloumi, Adel; Mohammadreze, Fallah

2012-01-01

One of the applications of ergonomics disciplinary is designing driver workstation compatible to users' characteristics. The aim of this study was evaluation of interior design of Shoka vehicle with respect to the accommodation for Iranian population and proposing suggestions for customizing design of this vehicle. This study was a descriptive-analytical study conducted among thirty men from Iranian drivers population in 5, 50, 95 percentiles of the stature variable. Objective variables related to the occupant packaging and vehicle visual aspects including anthropometric variables, frontal, lateral, and side view and so on were investigated first. Then, subjective variables related to the driver mental workload and body comfort discomfort were studied using BMDMW and comfort questionnaires during 2-hour driving trial sessions. Occupant packaging variables and hand-arm angle showed the least accommodation percent (%53). Seating angles showed low accommodation as well (%73). Among three percentile groups there were no significant differences between the mean values of mental workload during two hours driving task. And, the mean value related to the comfort discomfort was 3.9 during driving sessions. Considering the findings in this study, it can be conclude that seating angles need correction and optimization. Taking mental workload results into account, it can be concluded that the interior design of the studied car had no influence on drivers' mental workload. From the aspect of comfort discomfort, Shoka vehicle showed neutral state among drivers. Optimizing seating angles, decreasing vibration, correcting stiffness of seating pan are suggested for customization of the ergonomics aspect of this vehicle.

Changes in Knee Biomechanics After a Hip-Abductor Strengthening Protocol for Runners With Patellofemoral Pain Syndrome

PubMed Central

Ferber, Reed; Kendall, Karen D.; Farr, Lindsay

2011-01-01

Abstract Context: Very few authors have investigated the relationship between hip-abductor muscle strength and frontal-plane knee mechanics during running. Objective: To investigate this relationship using a 3-week hip-abductor muscle-strengthening program to identify changes in strength, pain, and biomechanics in runners with patellofemoral pain syndrome (PFPS). Design: Cohort study. Setting: University-based clinical research laboratory. Patients or Other Participants: Fifteen individuals (5 men, 10 women) with PFPS and 10 individuals without PFPS (4 men, 6 women) participated. Intervention(s): The patients with PFPS completed a 3-week hip-abductor strengthening protocol; control participants did not. Main Outcome Measure(s): The dependent variables of interest were maximal isometric hip-abductor muscle strength, 2-dimensional peak knee genu valgum angle, and stride-to-stride knee-joint variability. All measures were recorded at baseline and 3 weeks later. Between-groups differences were compared using repeated-measures analyses of variance. Results: At baseline, the PFPS group exhibited reduced strength, no difference in peak genu valgum angle, and increased stride-to-stride knee-joint variability compared with the control group. After the 3-week protocol, the PFPS group demonstrated increased strength, less pain, no change in peak genu valgum angle, and reduced stride-to-stride knee-joint variability compared with baseline. Conclusions: A 3-week hip-abductor muscle-strengthening protocol was effective in increasing muscle strength and decreasing pain and stride-to-stride knee-joint variability in individuals with PFPS. However, concomitant changes in peak knee genu valgum angle were not observed. PMID:21391799

Asronomical refraction: Computational methods for all zenith angles

NASA Technical Reports Server (NTRS)

Auer, L. H.; Standish, E. M.

2000-01-01

It is shown that the problem of computing astronomical refraction for any value of the zenith angle may be reduced to a simple, nonsingular, numerical quadrature when the proper choice is made for the independent variable of integration.

Wigner Distribution for Angle Coordinates in Quantum Mechanics.

ERIC Educational Resources Information Center

Mukunda, N.

1979-01-01

Shows how to extend Wigner distribution functions, and Weyl correspondence between quantum and classical variables, from the usual kind of canonically conjugate position and momentum operators to the case of an angle and angular momentum operator pair. (Author/GA)

Investigation on the Inertance Tubes of Pulse Tube Cryocooler Without Reservoir

NASA Astrophysics Data System (ADS)

Liu, Y. J.; Yang, L. W.; Liang, J. T.; Hong, G. T.

2010-04-01

Phase angle is of vital importance for high-efficiency pulse tube cryocoolers (PTCs). Inertance tube as the main phase shifter is useful for the PTCs to obtain appropriate phase angle. Experiments of inertance tube without reservoir under variable frequency, variable length and diameter of inertance tube and variable pressure amplitude are investigated respectively. In addition, the authors used DeltaEC, a computer program to predict the performance of low-amplitude thermoacoustic engines, to simulate the effects of inertance tube without reservoir. According to the comparison of experiments and theoretical simulations, DeltaEC method is feasible and effective to direct and improve the design of inertance tubes.

A Textile-Based Wearable Sensing Device Designed for Monitoring the Flexion Angle of Elbow and Knee Movements

PubMed Central

Shyr, Tien-Wei; Shie, Jing-Wen; Jiang, Chang-Han; Li, Jung-Jen

2014-01-01

In this work a wearable gesture sensing device consisting of a textile strain sensor, using elastic conductive webbing, was designed for monitoring the flexion angle of elbow and knee movements. The elastic conductive webbing shows a linear response of resistance to the flexion angle. The wearable gesture sensing device was calibrated and then the flexion angle-resistance equation was established using an assembled gesture sensing apparatus with a variable resistor and a protractor. The proposed device successfully monitored the flexion angle during elbow and knee movements. PMID:24577526

Angle-of-Attack-Modulated Terminal Point Control for Neptune Aerocapture

NASA Technical Reports Server (NTRS)

Queen, Eric M.

2004-01-01

An aerocapture guidance algorithm based on a calculus of variations approach is developed, using angle of attack as the primary control variable. Bank angle is used as a secondary control to alleviate angle of attack extremes and to control inclination. The guidance equations are derived in detail. The controller has very small onboard computational requirements and is robust to atmospheric and aerodynamic dispersions. The algorithm is applied to aerocapture at Neptune. Three versions of the controller are considered with varying angle of attack authority. The three versions of the controller are evaluated using Monte Carlo simulations with expected dispersions.

The VSPA Foot: A Quasi-Passive Ankle-Foot Prosthesis With Continuously Variable Stiffness.

PubMed

Shepherd, Max K; Rouse, Elliott J

2017-12-01

Most commercially available prosthetic feet do not exhibit a biomimetic torque-angle relationship, and are unable to modulate their mechanics to assist with other mobility tasks, such as stairs and ramps. In this paper, we present a quasi-passive ankle-foot prosthesis with a customizable torque-angle curve and an ability to quickly modulate ankle stiffness between tasks. The customizable torque-angle curve is obtained with a cam-based transmission and a fiberglass leaf spring. To achieve variable stiffness, the leaf spring's support conditions can be actively modulated by a small motor, shifting the torque-angle curve to be more or less stiff. We introduce the design, characterize the available torque-angle curves, and present kinematics from a transtibial amputee subject performing level-ground walking, stair ascent/descent, and ramp ascent/descent. The subject exhibited a more normative range of motion on stairs and ramps at lower stiffness levels, and preferred different stiffness levels for each task. Paired with an appropriate intent recognition system, our novel ankle prosthesis could improve gait biomechanics during walking and many other mobility tasks.

Video stimuli reduce object-directed imitation accuracy: a novel two-person motion-tracking approach.

PubMed

Reader, Arran T; Holmes, Nicholas P

2015-01-01

Imitation is an important form of social behavior, and research has aimed to discover and explain the neural and kinematic aspects of imitation. However, much of this research has featured single participants imitating in response to pre-recorded video stimuli. This is in spite of findings that show reduced neural activation to video vs. real life movement stimuli, particularly in the motor cortex. We investigated the degree to which video stimuli may affect the imitation process using a novel motion tracking paradigm with high spatial and temporal resolution. We recorded 14 positions on the hands, arms, and heads of two individuals in an imitation experiment. One individual freely moved within given parameters (moving balls across a series of pegs) and a second participant imitated. This task was performed with either simple (one ball) or complex (three balls) movement difficulty, and either face-to-face or via a live video projection. After an exploratory analysis, three dependent variables were chosen for examination: 3D grip position, joint angles in the arm, and grip aperture. A cross-correlation and multivariate analysis revealed that object-directed imitation task accuracy (as represented by grip position) was reduced in video compared to face-to-face feedback, and in complex compared to simple difficulty. This was most prevalent in the left-right and forward-back motions, relevant to the imitator sitting face-to-face with the actor or with a live projected video of the same actor. The results suggest that for tasks which require object-directed imitation, video stimuli may not be an ecologically valid way to present task materials. However, no similar effects were found in the joint angle and grip aperture variables, suggesting that there are limits to the influence of video stimuli on imitation. The implications of these results are discussed with regards to previous findings, and with suggestions for future experimentation.

Pickett angles and Cremer-Pople coordinates as collective variables for the enhanced sampling of six-membered ring conformations

NASA Astrophysics Data System (ADS)

Sega, M.; Autieri, E.; Pederiva, F.

2011-01-01

Although completely equivalent for the description of puckered ring conformers, the two popular coordinates sets of Strauss-Pickett dihedral angles and Cremer-Pople spherical coordinates are shown to have contrasting features when employed as collective variables in free-energy calculations with accelerated sampling techniques. Results from a 100 ns molecular dynamics simulation at conformational equilibrium and from combined metadynamics/umbrella sampling calculations of glucose are exploited to elucidate these differences.

Interpreting vegetation reflectance measurements as a function of solar zenith angle

NASA Technical Reports Server (NTRS)

Kimes, D. S.; Smith, J. A.; Ranson, K. J.

1979-01-01

Spectral hemispherical-conical reflectances of a nadir looking sensor were taken throughout the day for a lodgepole pine and two grass canopies. Mathematical simulations of both spectral hemispherical-conical and bi-hemispherical reflectances were performed for two theoretical canopies of contrasting geometric structure. These results and comparisons with literature studies showed a great amount of variability of vegetation canopy reflectances as a function of solar zenith angle. Explanations for this variability are discussed and recommendations for further measurements are proposed.

Helicopter Maneuverability and Agility Design Sensitivity and Air Combat Maneuver Data Correlation Study

DTIC Science & Technology

1991-10-01

o n tr o l sy st em St ic ks , m ix in g, S A S , se rv os L an d in g I n te rf ac e - V er ti ca l lo ad s - In pl an e lo ad s E xt...ROUTINE ALPNPlt ,INPUT VARIABLE QFiQWrM »OUTPUT VARIABLE OP1LO ;LOW ANGLE BAP NABE EXP -30.0,30.0,5.0 jLOWER LIBIT. UPPER LIMIT, DELTA ; LOK ANGLE BAP

Experimental investigation of piercing of high-strength steels within a critical range of slant angle

NASA Astrophysics Data System (ADS)

Senn, S.; Liewald, M.

2017-09-01

Deep drawn parts often do have complex designs and, therefore, must be trimmed or punched subsequently in a second stage. Due to the complex part geometry, most punching areas do reveal critical slant angle (angle between part surface and ram movement direction) different to perpendicular direction. Piercing within a critical range of slant angle may lead to severe damage of the cutting tool. Consequently, expensive cam units are required to transform the ram moving direction in order to perform the piercing process perpendicularly to the local part surface. For modern sheet metals, however, the described critical angle of attack has not been investigated adequately until now. Therefore, cam units are used in cases in which regular piercing with high slant angle wouldn’t be possible. Purpose of this study is to investigate influencing factors and their effect on punch damage during piercing of high strength steels with slant angles. Therefore, a modular shearing tool was designed, which allows to simply switch die parts to vary cutting clearance and cutting angle. The target size of the study is to measure the lateral deviation of the punch which is monitored by an eddy current sensor. The sensor is located in the downholder and measures the lateral punch deviation in-line during manufacturing. The deviation is mainly influenced by slant angle of workpiece surface. In relation to slang angle and sheet thickness the clearance has a small influence on the measured punch deflection.

New approach to probability estimate of femoral neck fracture by fall (Slovak regression model).

PubMed

Wendlova, J

2009-01-01

3,216 Slovak women with primary or secondary osteoporosis or osteopenia, aged 20-89 years, were examined with the bone densitometer DXA (dual energy X-ray absorptiometry, GE, Prodigy - Primo), x = 58.9, 95% C.I. (58.42; 59.38). The values of the following variables for each patient were measured: FSI (femur strength index), T-score total hip left, alpha angle - left, theta angle - left, HAL (hip axis length) left, BMI (body mass index) was calculated from the height and weight of the patients. Regression model determined the following order of independent variables according to the intensity of their influence upon the occurrence of values of dependent FSI variable: 1. BMI, 2. theta angle, 3. T-score total hip, 4. alpha angle, 5. HAL. The regression model equation, calculated from the variables monitored in the study, enables a doctor in praxis to determine the probability magnitude (absolute risk) for the occurrence of pathological value of FSI (FSI < 1) in the femoral neck area, i. e., allows for probability estimate of a femoral neck fracture by fall for Slovak women. 1. The Slovak regression model differs from regression models, published until now, in chosen independent variables and a dependent variable, belonging to biomechanical variables, characterising the bone quality. 2. The Slovak regression model excludes the inaccuracies of other models, which are not able to define precisely the current and past clinical condition of tested patients (e.g., to define the length and dose of exposure to risk factors). 3. The Slovak regression model opens the way to a new method of estimating the probability (absolute risk) or the odds for a femoral neck fracture by fall, based upon the bone quality determination. 4. It is assumed that the development will proceed by improving the methods enabling to measure the bone quality, determining the probability of fracture by fall (Tab. 6, Fig. 3, Ref. 22). Full Text (Free, PDF) www.bmj.sk.

Multi-Layer Artificial Neural Networks Based MPPT-Pitch Angle Control of a Tidal Stream Generator

PubMed Central

Bouallègue, Soufiene; Garrido, Aitor J.; Haggège, Joseph

2018-01-01

Artificial intelligence technologies are widely investigated as a promising technique for tackling complex and ill-defined problems. In this context, artificial neural networks methodology has been considered as an effective tool to handle renewable energy systems. Thereby, the use of Tidal Stream Generator (TSG) systems aim to provide clean and reliable electrical power. However, the power captured from tidal currents is highly disturbed due to the swell effect and the periodicity of the tidal current phenomenon. In order to improve the quality of the generated power, this paper focuses on the power smoothing control. For this purpose, a novel Artificial Neural Network (ANN) is investigated and implemented to provide the proper rotational speed reference and the blade pitch angle. The ANN supervisor adequately switches the system in variable speed and power limitation modes. In order to recover the maximum power from the tides, a rotational speed control is applied to the rotor side converter following the Maximum Power Point Tracking (MPPT) generated from the ANN block. In case of strong tidal currents, a pitch angle control is set based on the ANN approach to keep the system operating within safe limits. Two study cases were performed to test the performance of the output power. Simulation results demonstrate that the implemented control strategies achieve a smoothed generated power in the case of swell disturbances. PMID:29695127

Multi-Layer Artificial Neural Networks Based MPPT-Pitch Angle Control of a Tidal Stream Generator.

PubMed

Ghefiri, Khaoula; Bouallègue, Soufiene; Garrido, Izaskun; Garrido, Aitor J; Haggège, Joseph

2018-04-24

Artificial intelligence technologies are widely investigated as a promising technique for tackling complex and ill-defined problems. In this context, artificial neural networks methodology has been considered as an effective tool to handle renewable energy systems. Thereby, the use of Tidal Stream Generator (TSG) systems aim to provide clean and reliable electrical power. However, the power captured from tidal currents is highly disturbed due to the swell effect and the periodicity of the tidal current phenomenon. In order to improve the quality of the generated power, this paper focuses on the power smoothing control. For this purpose, a novel Artificial Neural Network (ANN) is investigated and implemented to provide the proper rotational speed reference and the blade pitch angle. The ANN supervisor adequately switches the system in variable speed and power limitation modes. In order to recover the maximum power from the tides, a rotational speed control is applied to the rotor side converter following the Maximum Power Point Tracking (MPPT) generated from the ANN block. In case of strong tidal currents, a pitch angle control is set based on the ANN approach to keep the system operating within safe limits. Two study cases were performed to test the performance of the output power. Simulation results demonstrate that the implemented control strategies achieve a smoothed generated power in the case of swell disturbances.

Using wood creep data to discuss the contribution of cell-wall reinforcing material.

PubMed

Gril, Joseph; Hunt, David; Thibaut, Bernard

2004-01-01

Longitudinal four-point creep bending tests were performed on small clear-wood spruce specimens having various microfibrillar angles. Cell-wall compliance was deduced from macroscopic data by accounting for porosity. Time-dependent compliance was converted into complex compliance and rigidity using the value and the slope of the compliance versus logarithm of time. Complex rigidity plots of all specimens, for the time range 10(3)-10(6) s, could be superimposed by a horizontal shift depending on the microfibrillar angle. The shape of complex trajectories allowed a decomposition of the cell-wall relaxation modulus as the sum of an elastic contribution function of the microfibrillar angle and a time-dependent term unrelated to it, and suggested a discussion on the contribution of the various cell-wall layers to the observed relaxation process.

Crystal structure of cis-tetra-aqua-dichlorido-cobalt(II) sulfolane disolvate.

PubMed

Boudraa, Mhamed; Bouacida, Sofiane; Bouchareb, Hasna; Merazig, Hocine; Chtoun, El Hossain

2015-02-01

In the title compound, [CoCl2(H2O)4]·2C4H8SO2, the Co(II) cation is located on the twofold rotation axis and is coordinated by four water mol-ecules and two adjacent chloride ligands in a slightly distorted octa-hedral coordination environment. The cisoid angles are in the range 83.27 (5)-99.66 (2)°. The three transoid angles deviate significantly from the ideal linear angle. The crystal packing can be described as a linear arrangement of complex units along c formed by bifurcated O-H⋯Cl hydrogen bonds between two water mol-ecules from one complex unit towards one chloride ligand of the neighbouring complex. Two solvent mol-ecules per complex are attached to this infinite chain via O-H⋯O hydrogen bonds in which water mol-ecules act as the hydrogen-bond donor and sulfolane O atoms as the hydrogen-bond acceptor sites.

On the viewing angle dependence of blazar variability

NASA Astrophysics Data System (ADS)

Eldar, Avigdor; Levinson, Amir

2000-05-01

Internal shocks propagating through an ambient radiation field are subject to a radiative drag that, under certain conditions, can significantly affect their dynamics, and consequently the evolution of the beaming cone of emission produced behind the shocks. The resultant change of the Doppler factor combined with opacity effects leads to a strong dependence on the viewing angle of the variability pattern produced by such systems; specifically, the shape of the light curves and the characteristics of correlated emission. One implication is that objects oriented at relatively large viewing angles to the observer should exhibit a higher level of activity at high synchrotron frequencies (above the self-absorption frequency), and also at gamma-ray energies below the threshold energy of pair production, than at lower (radio/millimetre) frequencies.

Crustal structure of a transform plate boundary: San Francisco Bay and the central California continental margin

USGS Publications Warehouse

Holbrook, W.S.; Brocher, T.M.; ten Brink, Uri S.; Hole, J.A.

1996-01-01

Wide-angle seismic data collected during the Bay Area Seismic Imaging Experiment provide new glimpses of the deep structure of the San Francisco Bay Area Block and across the offshore continental margin. San Francisco Bay is underlain by a veneer (<300 m) of sediments, beneath which P wave velocities increase rapidly from 5.2 km/s to 6.0 km/s at 7 km depth, consistent with rocks of the Franciscan subduction assemblage. The base of the Franciscan at-15-18 km depth is marked by a strong wide-angle reflector, beneath which lies an 8- to 10-km-thick lower crust with an average velocity of 6.75??0.15 km/s. The lower crust of the Bay Area Block may be oceanic in origin, but its structure and reflectivity indicate that it has been modified by shearing and/or magmatic intrusion. Wide-angle reflections define two layers within the lower crust, with velocities of 6.4-6.6 km/s and 6.9-7.3 km/s. Prominent subhorizontal reflectivity observed at near-vertical incidence resides principally in the lowermost layer, the top of which corresponds to the "6-s reflector" of Brocher et al. [1994]. Rheological modeling suggests that the lower crust beneath the 6-s reflector is the weakest part of the lithosphere; the horizontal shear zone suggested by Furlong et al. [1989] to link the San Andreas and Hayward/Calaveras fault systems may actually be a broad zone of shear deformation occupying the lowermost crust. A transect across the continental margin from the paleotrench to the Hayward fault shows a deep crustal structure that is more complex than previously realized. Strong lateral variability in seismic velocity and wide-angle reflectivity suggests that crustal composition changes across major transcurrent fault systems. Pacific oceanic crust extends 40-50 km landward of the paleotrench but, contrary to prior models, probably does not continue beneath the Salinian Block, a Cretaceous arc complex that lies west of the San Andreas fault in the Bay Area. The thickness (10 km) and high lower-crustal velocity of Pacific oceanic crust suggest that it was underplated by magmatism associated with the nearby Pioneer seamount. The Salinian Block consists of a 15-km-thick layer of velocity 6.0-6.2 km/s overlying a 5-km-thick, high-velocity (7.0 km/s) lower crust that may be oceanic crust, Cretaceous arc-derived lower crust, or a magmatically underplated layer. The strong structural variability across the margin attests to the activity of strike-slip faulting prior to and during development of the transcurrent Pacific/North American plate boundary around 29 Ma. Copyright 1996 by the American Geophysical Union.

Geological and Structural Patterns on Titan Enhanced Through Cassini's SAR PCA and High-Resolution Radiometry

NASA Astrophysics Data System (ADS)

Paganelli, F.; Schubert, G.; Lopes, R. M. C.; Malaska, M.; Le Gall, A. A.; Kirk, R. L.

2016-12-01

The current SAR data coverage on Titan encompasses several areas in which multiple radar passes are present and overlapping, providing additional information to aid the interpretation of geological and structural features. We exploit the different combinations of look direction and variable incidence angle to examine Cassini Synthetic Aperture RADAR (SAR) data using the Principal Component Analysis (PCA) technique and high-resolution radiometry, as a tool to aid in the interpretation of geological and structural features. Look direction and variable incidence angle is of particular importance in the analysis of variance in the images, which aid in the perception and identification of geological and structural features, as extensively demonstrated in Earth and planetary examples. The PCA enhancement technique uses projected non-ortho-rectified SAR imagery in order to maintain the inherent differences in scattering and geometric properties due to the different look directions, while enhancing the geometry of surface features. The PC2 component provides a stereo view of the areas in which complex surface features and structural patterns can be enhanced and outlined. We focus on several areas of interest, in older and recently acquired flybys, in which evidence of geological and structural features can be enhanced and outlined in the PC1 and PC2 components. Results of this technique provide enhanced geometry and insights into the interpretation of the observed geological and structural features, thus allowing a better understanding towards the geology and tectonics on Titan.

Changes and variations in the turning angle of Arctic sea ice

NASA Astrophysics Data System (ADS)

Ukita, J.; Honda, M.; Ishizuka, S.

2012-12-01

The motion of sea ice is under influences of forcing from winds and currents and of sea ice properties. In facing rapidly changing Arctic climate we are interested in whether we observe and quantify changes in sea ice conditions reflected in its velocity field. Theoretical consideration on the freedrift model predicts a change in the sea ice turning angle with respect to the direction of forcing wind in association with thinning sea ice thickness. Possible changes in atmospheric and ocean boundary layer conditions may be reflected in the sea ice turning angle through modification of both atmospheric and oceanic Ekman spirals. With these in mind this study examines statistical properties of the turning angle of the Arctic sea ice and compares them with atmospheric/ice/ocean conditions for the period of 1979-2010 on the basis of IABP buoy data. Preliminary results indicate that over this period the turning angle has varying trends depending on different seasons. We found weakly significant (>90% level) changes in the turning angle from August to October with the maximum trend in October. The direction of trends is counter-clockwise with respect to the geostrophic wind direction, which is consistent with the thinning of sea ice. The interannual variability of the turning angle for this peak season of the reduced sea ice cover is not the same as that of the Arctic SIE. However, in recent years the turning angle appears to covary with the surface air temperature, providing supporting evidence for the relationship between the angle and sea ice thickness. In the presentation we will provide results on the relationships between the turning angle and atmospheric and oceanic variables and further discuss their implications.

Reflection and Refraction of Light in Absorbing Media

NASA Astrophysics Data System (ADS)

Katsumata, Koichi; Sasaki, Shosuke

2018-05-01

The results of a rigorous calculation of optical phenomena in absorbing media based on Maxwell's equations are reported. In the case of an absorbing dielectric, we assume a complex dielectric constant. We find an expression for the angle of refraction as a function of the incident angle and the real and imaginary parts of the complex dielectric constant, all of which are real. The amplitudes of the reflected and transmitted waves are calculated on the same footing. These amplitudes are shown to be complex, from which we deduce the magnitude and phase change of the reflection and transmission coefficients. The same argument applies to an absorbing magnetic material if we replace the complex dielectric constant by a complex magnetic permeability.

Sparse array angle estimation using reduced-dimension ESPRIT-MUSIC in MIMO radar.

PubMed

Zhang, Chaozhu; Pang, Yucai

2013-01-01

Sparse linear arrays provide better performance than the filled linear arrays in terms of angle estimation and resolution with reduced size and low cost. However, they are subject to manifold ambiguity. In this paper, both the transmit array and receive array are sparse linear arrays in the bistatic MIMO radar. Firstly, we present an ESPRIT-MUSIC method in which ESPRIT algorithm is used to obtain ambiguous angle estimates. The disambiguation algorithm uses MUSIC-based procedure to identify the true direction cosine estimate from a set of ambiguous candidate estimates. The paired transmit angle and receive angle can be estimated and the manifold ambiguity can be solved. However, the proposed algorithm has high computational complexity due to the requirement of two-dimension search. Further, the Reduced-Dimension ESPRIT-MUSIC (RD-ESPRIT-MUSIC) is proposed to reduce the complexity of the algorithm. And the RD-ESPRIT-MUSIC only demands one-dimension search. Simulation results demonstrate the effectiveness of the method.

Gravity dependence of subjective visual vertical variability.

PubMed

Tarnutzer, A A; Bockisch, C; Straumann, D; Olasagasti, I

2009-09-01

The brain integrates sensory input from the otolith organs, the semicircular canals, and the somatosensory and visual systems to determine self-orientation relative to gravity. Only the otoliths directly sense the gravito-inertial force vector and therefore provide the major input for perceiving static head-roll relative to gravity, as measured by the subjective visual vertical (SVV). Intraindividual SVV variability increases with head roll, which suggests that the effectiveness of the otolith signal is roll-angle dependent. We asked whether SVV variability reflects the spatial distribution of the otolithic sensors and the otolith-derived acceleration estimate. Subjects were placed in different roll orientations (0-360 degrees, 15 degrees steps) and asked to align an arrow with perceived vertical. Variability was minimal in upright, increased with head-roll peaking around 120-135 degrees, and decreased to intermediate values at 180 degrees. Otolith-dependent variability was modeled by taking into consideration the nonuniform distribution of the otolith afferents and their nonlinear firing rate. The otolith-derived estimate was combined with an internal bias shifting the estimated gravity-vector toward the body-longitudinal. Assuming an efficient otolith estimator at all roll angles, peak variability of the model matched our data; however, modeled variability in upside-down and upright positions was very similar, which is at odds with our findings. By decreasing the effectiveness of the otolith estimator with increasing roll, simulated variability matched our experimental findings better. We suggest that modulations of SVV precision in the roll plane are related to the properties of the otolith sensors and to central computational mechanisms that are not optimally tuned for roll-angles distant from upright.

Defining scenarios of future vectors of change in marine life and associated economic sectors

NASA Astrophysics Data System (ADS)

Groeneveld, Rolf A.; Bosello, Francesco; Butenschön, Momme; Elliott, Mike; Peck, Myron A.; Pinnegar, John K.

2018-02-01

Addressing the multitude of challenges in marine policy requires an integrated approach that considers the multitude of drivers, pressures, and interests, from several disciplinary angles. Scenarios are needed to harmonise the analyses of different components of the marine system, and to deal with the uncertainty and complexity of the societal and biogeophysical dynamics in the system. This study considers a set of socio-economic scenarios to (1) explore possible futures in relation to marine invasive species, outbreak forming species, and gradual changes in species distribution and productivity; and (2) harmonise the projection modelling performed within associated studies. The exercise demonstrates that developing interdisciplinary scenarios as developed in this study is particularly complicated due to (1) the wide variety in endogeneity or exogeneity of variables in the different analyses involved; (2) the dual role of policy decisions as variables in a scenario or decisions to be evaluated and compared to other decisions; and (3) the substantial difference in time scale between societal and physical drivers.

Development Of A Parallel Performance Model For The THOR Neutral Particle Transport Code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yessayan, Raffi; Azmy, Yousry; Schunert, Sebastian

The THOR neutral particle transport code enables simulation of complex geometries for various problems from reactor simulations to nuclear non-proliferation. It is undergoing a thorough V&V requiring computational efficiency. This has motivated various improvements including angular parallelization, outer iteration acceleration, and development of peripheral tools. For guiding future improvements to the code’s efficiency, better characterization of its parallel performance is useful. A parallel performance model (PPM) can be used to evaluate the benefits of modifications and to identify performance bottlenecks. Using INL’s Falcon HPC, the PPM development incorporates an evaluation of network communication behavior over heterogeneous links and a functionalmore » characterization of the per-cell/angle/group runtime of each major code component. After evaluating several possible sources of variability, this resulted in a communication model and a parallel portion model. The former’s accuracy is bounded by the variability of communication on Falcon while the latter has an error on the order of 1%.« less

2D versus 3D in the kinematic analysis of the horse at the trot.

PubMed

Miró, F; Santos, R; Garrido-Castro, J L; Galisteo, A M; Medina-Carnicer, R

2009-08-01

The handled trot of three Lusitano Purebred stallions was analyzed by using 2D and 3D kinematical analysis methods. Using the same capture and analysis system, 2D and 3D data of some linear (stride length, maximal height of the hoof trajectories) and angular (angular range of motion, inclination of bone segments) variables were obtained. A paired Student T-test was performed in order to detect statistically significant differences between data resulting from the two methodologies With respect to the angular variables, there were significant differences in scapula inclination, shoulder angle, cannon inclination and protraction-retraction angle in the forelimb variables, but none of them were statistically different in the hind limb. Differences between the two methods were found in most of the linear variables analyzed.

Contact angle control of sessile drops on a tensioned web

NASA Astrophysics Data System (ADS)

Park, Janghoon; Kim, Dongguk; Lee, Changwoo

2018-04-01

In this study, the influence of the change of tension applied to flexible and thin web substrate on the contact angle of sessile drop in roll-to-roll system was investigated. Graphene oxide and deionized water solutions were used in the experiments. Tension was changed to 29, 49, and 69 N, and the casting distance of the micropipette and the material was set to 10, 20, and 40 mm, and the droplet volume was set to 10, 20, and 30 μL, respectively. Statistical analysis of three variables and analysis of the variance methodology showed that the casting distance was most significant for the contact angle change, and the most interesting tension variable was also affected. The change in tension caused the maximum contact angle to change by 5.5°. The tension was not uniform in the width direction. When the droplet was applied in the same direction in the width direction, it was confirmed that the tension unevenness had great influence on the contact angle up to 11°. Finally, the casting distance, which has a large effect on the contact angle, was calibrated in the width direction to reduce the width direction contact angle deviation to 1%. This study can be applied to fine patterning research using continuous inkjet printing and aerosol jet printing, which are roll-to-roll processes based on droplet handling.

Application of a symbolic motion structure representation algorithm to identify upper extremity kinematic changes during a repetitive task.

PubMed

Whittaker, Rachel L; Park, Woojin; Dickerson, Clark R

2018-04-27

Efficient and holistic identification of fatigue-induced movement strategies can be limited by large between-subject variability in descriptors of joint angle data. One promising alternative to traditional, or computationally intensive methods is the symbolic motion structure representation algorithm (SMSR), which identifies the basic spatial-temporal structure of joint angle data using string descriptors of temporal joint angle trajectories. This study attempted to use the SMSR to identify changes in upper extremity time series joint angle data during a repetitive goal directed task causing muscle fatigue. Twenty-eight participants (15 M, 13 F) performed a seated repetitive task until fatigued. Upper extremity joint angles were extracted from motion capture for representative task cycles. SMSRs, averages and ranges of several joint angles were compared at the start and end of the repetitive task to identify kinematic changes with fatigue. At the group level, significant increases in the range of all joint angle data existed with large between-subject variability that posed a challenge to the interpretation of these fatigue-related changes. However, changes in the SMSRs across participants effectively summarized the adoption of adaptive movement strategies. This establishes SMSR as a viable, logical, and sensitive method of fatigue identification via kinematic changes, with novel application and pragmatism for visual assessment of fatigue development. Copyright © 2018 Elsevier Ltd. All rights reserved.

Adaptive sliding mode back-stepping pitch angle control of a variable-displacement pump controlled pitch system for wind turbines.

PubMed

Yin, Xiu-xing; Lin, Yong-gang; Li, Wei; Liu, Hong-wei; Gu, Ya-jing

2015-09-01

A variable-displacement pump controlled pitch system is proposed to mitigate generator power and flap-wise load fluctuations for wind turbines. The pitch system mainly consists of a variable-displacement hydraulic pump, a fixed-displacement hydraulic motor and a gear set. The hydraulic motor can be accurately regulated by controlling the pump displacement and fluid flows to change the pitch angle through the gear set. The detailed mathematical representation and dynamic characteristics of the proposed pitch system are thoroughly analyzed. An adaptive sliding mode pump displacement controller and a back-stepping stroke piston controller are designed for the proposed pitch system such that the resulting pitch angle tracks its desired value regardless of external disturbances and uncertainties. The effectiveness and control efficiency of the proposed pitch system and controllers have been verified by using realistic dataset of a 750 kW research wind turbine. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Native tandem and ion mobility mass spectrometry highlight structural and modular similarities in clustered-regularly-interspaced shot-palindromic-repeats (CRISPR)-associated protein complexes from Escherichia coli and Pseudomonas aeruginosa.

PubMed

van Duijn, Esther; Barbu, Ioana M; Barendregt, Arjan; Jore, Matthijs M; Wiedenheft, Blake; Lundgren, Magnus; Westra, Edze R; Brouns, Stan J J; Doudna, Jennifer A; van der Oost, John; Heck, Albert J R

2012-11-01

The CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated genes) immune system of bacteria and archaea provides acquired resistance against viruses and plasmids, by a strategy analogous to RNA-interference. Key components of the defense system are ribonucleoprotein complexes, the composition of which appears highly variable in different CRISPR/Cas subtypes. Previous studies combined mass spectrometry, electron microscopy, and small angle x-ray scattering to demonstrate that the E. coli Cascade complex (405 kDa) and the P. aeruginosa Csy-complex (350 kDa) are similar in that they share a central spiral-shaped hexameric structure, flanked by associating proteins and one CRISPR RNA. Recently, a cryo-electron microscopy structure of Cascade revealed that the CRISPR RNA molecule resides in a groove of the hexameric backbone. For both complexes we here describe the use of native mass spectrometry in combination with ion mobility mass spectrometry to assign a stable core surrounded by more loosely associated modules. Via computational modeling subcomplex structures were proposed that relate to the experimental IMMS data. Despite the absence of obvious sequence homology between several subunits, detailed analysis of sub-complexes strongly suggests analogy between subunits of the two complexes. Probing the specific association of E. coli Cascade/crRNA to its complementary DNA target reveals a conformational change. All together these findings provide relevant new information about the potential assembly process of the two CRISPR-associated complexes.

Complex earthquake rupture and local tsunamis

USGS Publications Warehouse

Geist, E.L.

2002-01-01

In contrast to far-field tsunami amplitudes that are fairly well predicted by the seismic moment of subduction zone earthquakes, there exists significant variation in the scaling of local tsunami amplitude with respect to seismic moment. From a global catalog of tsunami runup observations this variability is greatest for the most frequently occuring tsunamigenic subduction zone earthquakes in the magnitude range of 7 < Mw < 8.5. Variability in local tsunami runup scaling can be ascribed to tsunami source parameters that are independent of seismic moment: variations in the water depth in the source region, the combination of higher slip and lower shear modulus at shallow depth, and rupture complexity in the form of heterogeneous slip distribution patterns. The focus of this study is on the effect that rupture complexity has on the local tsunami wave field. A wide range of slip distribution patterns are generated using a stochastic, self-affine source model that is consistent with the falloff of far-field seismic displacement spectra at high frequencies. The synthetic slip distributions generated by the stochastic source model are discretized and the vertical displacement fields from point source elastic dislocation expressions are superimposed to compute the coseismic vertical displacement field. For shallow subduction zone earthquakes it is demonstrated that self-affine irregularities of the slip distribution result in significant variations in local tsunami amplitude. The effects of rupture complexity are less pronounced for earthquakes at greater depth or along faults with steep dip angles. For a test region along the Pacific coast of central Mexico, peak nearshore tsunami amplitude is calculated for a large number (N = 100) of synthetic slip distribution patterns, all with identical seismic moment (Mw = 8.1). Analysis of the results indicates that for earthquakes of a fixed location, geometry, and seismic moment, peak nearshore tsunami amplitude can vary by a factor of 3 or more. These results indicate that there is substantially more variation in the local tsunami wave field derived from the inherent complexity subduction zone earthquakes than predicted by a simple elastic dislocation model. Probabilistic methods that take into account variability in earthquake rupture processes are likely to yield more accurate assessments of tsunami hazards.

Auto-calibrated scanning-angle prism-type total internal reflection microscopy for nanometer-precision axial position determination and optional variable-illumination-depth pseudo total internal reflection microscopy

DOEpatents

Fang, Ning; Sun, Wei

2015-04-21

A method, apparatus, and system for improved VA-TIRFM microscopy. The method comprises automatically controlled calibration of one or more laser sources by precise control of presentation of each laser relative a sample for small incremental changes of incident angle over a range of critical TIR angles. The calibration then allows precise scanning of the sample for any of those calibrated angles for higher and more accurate resolution, and better reconstruction of the scans for super resolution reconstruction of the sample. Optionally the system can be controlled for incident angles of the excitation laser at sub-critical angles for pseudo TIRFM. Optionally both above-critical angle and sub critical angle measurements can be accomplished with the same system.

TFIIA changes the conformation of the DNA in TBP/TATA complexes and increases their kinetic stability.

PubMed

Hieb, Aaron R; Halsey, Wayne A; Betterton, Meredith D; Perkins, Thomas T; Kugel, Jennifer F; Goodrich, James A

2007-09-21

Eukaryotic mRNA transcription by RNA polymerase II is a highly regulated complex reaction involving numerous proteins. In order to control tissue and promoter specific gene expression, transcription factors must work in concert with each other and with the promoter DNA to form the proper architecture to activate the gene of interest. The TATA binding protein (TBP) binds to TATA boxes in core promoters and bends the TATA DNA. We have used quantitative solution fluorescence resonance energy transfer (FRET) and gel-based FRET (gelFRET) to determine the effect of TFIIA on the conformation of the DNA in TBP/TATA complexes and on the kinetic stability of these complexes. Our results indicate that human TFIIA decreases the angle to which human TBP bends consensus TATA DNA from 104 degrees to 80 degrees when calculated using a two-kink model. The kinetic stability of TBP/TATA complexes was greatly reduced by increasing the KCl concentration from 50 mM to 140 mM, which is more physiologically relevant. TFIIA significantly enhanced the kinetic stability of TBP/TATA complexes, thereby attenuating the effect of higher salt concentrations. We also found that TBP bent non-consensus TATA DNA to a lesser degree than consensus TATA DNA and complexes between TBP and a non-consensus TATA box were kinetically unstable even at 50 mM KCl. Interestingly, TFIIA increased the calculated bend angle and kinetic stability of complexes on a non-consensus TATA box, making them similar to those on a consensus TATA box. Our data show that TFIIA induces a conformational change within the TBP/TATA complex that enhances its stability under both in vitro and physiological salt conditions. Furthermore, we present a refined model for the effect that TFIIA has on DNA conformation that takes into account potential changes in bend angle as well as twist angle.

Shoulder pain and time dependent structure in wheelchair propulsion variability.

PubMed

Jayaraman, Chandrasekaran; Moon, Yaejin; Sosnoff, Jacob J

2016-07-01

Manual wheelchair propulsion places considerable repetitive mechanical strain on the upper limbs leading to shoulder injury and pain. While recent research indicates that the amount of variability in wheelchair propulsion and shoulder pain may be related. There has been minimal inquiry into the fluctuation over time (i.e. time-dependent structure) in wheelchair propulsion variability. Consequently the purpose of this investigation was to examine if the time-dependent structure in the wheelchair propulsion parameters are related to shoulder pain. 27 experienced wheelchair users manually propelled their own wheelchair fitted with a SMARTWheel on a roller at 1.1m/s for 3min. Time-dependent structure of cycle-to-cycle fluctuations in contact angle and inter push time interval was quantified using sample entropy (SampEn) and compared between the groups with/without shoulder pain using non-parametric statistics. Overall findings were, (1) variability observed in contact angle fluctuations during manual wheelchair propulsion is structured (Z=3.15;p<0.05), (2) individuals with shoulder pain exhibited higher SampEn magnitude for contact angle during wheelchair propulsion than those without pain (χ(2)(1)=6.12;p<0.05); and (3) SampEn of contact angle correlated significantly with self-reported shoulder pain (rs (WUSPI) =0.41;rs (VAS)=0.56;p<0.05). It was concluded that the time-dependent structure in wheelchair propulsion may provide novel information for tracking and monitoring shoulder pain. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Study of the Algorithm of Backtracking Decoupling and Adaptive Extended Kalman Filter Based on the Quaternion Expanded to the State Variable for Underwater Glider Navigation

PubMed Central

Huang, Haoqian; Chen, Xiyuan; Zhou, Zhikai; Xu, Yuan; Lv, Caiping

2014-01-01

High accuracy attitude and position determination is very important for underwater gliders. The cross-coupling among three attitude angles (heading angle, pitch angle and roll angle) becomes more serious when pitch or roll motion occurs. This cross-coupling makes attitude angles inaccurate or even erroneous. Therefore, the high accuracy attitude and position determination becomes a difficult problem for a practical underwater glider. To solve this problem, this paper proposes backing decoupling and adaptive extended Kalman filter (EKF) based on the quaternion expanded to the state variable (BD-AEKF). The backtracking decoupling can eliminate effectively the cross-coupling among the three attitudes when pitch or roll motion occurs. After decoupling, the adaptive extended Kalman filter (AEKF) based on quaternion expanded to the state variable further smoothes the filtering output to improve the accuracy and stability of attitude and position determination. In order to evaluate the performance of the proposed BD-AEKF method, the pitch and roll motion are simulated and the proposed method performance is analyzed and compared with the traditional method. Simulation results demonstrate the proposed BD-AEKF performs better. Furthermore, for further verification, a new underwater navigation system is designed, and the three-axis non-magnetic turn table experiments and the vehicle experiments are done. The results show that the proposed BD-AEKF is effective in eliminating cross-coupling and reducing the errors compared with the conventional method. PMID:25479331

Study of the algorithm of backtracking decoupling and adaptive extended Kalman filter based on the quaternion expanded to the state variable for underwater glider navigation.

PubMed

Huang, Haoqian; Chen, Xiyuan; Zhou, Zhikai; Xu, Yuan; Lv, Caiping

2014-12-03

High accuracy attitude and position determination is very important for underwater gliders. The cross-coupling among three attitude angles (heading angle, pitch angle and roll angle) becomes more serious when pitch or roll motion occurs. This cross-coupling makes attitude angles inaccurate or even erroneous. Therefore, the high accuracy attitude and position determination becomes a difficult problem for a practical underwater glider. To solve this problem, this paper proposes backing decoupling and adaptive extended Kalman filter (EKF) based on the quaternion expanded to the state variable (BD-AEKF). The backtracking decoupling can eliminate effectively the cross-coupling among the three attitudes when pitch or roll motion occurs. After decoupling, the adaptive extended Kalman filter (AEKF) based on quaternion expanded to the state variable further smoothes the filtering output to improve the accuracy and stability of attitude and position determination. In order to evaluate the performance of the proposed BD-AEKF method, the pitch and roll motion are simulated and the proposed method performance is analyzed and compared with the traditional method. Simulation results demonstrate the proposed BD-AEKF performs better. Furthermore, for further verification, a new underwater navigation system is designed, and the three-axis non-magnetic turn table experiments and the vehicle experiments are done. The results show that the proposed BD-AEKF is effective in eliminating cross-coupling and reducing the errors compared with the conventional method.

Movement Variability Increases With Shoulder Pain When Compensatory Strategies of the Upper Body Are Constrained.

PubMed

López-Pascual, Juan; Page, Álvaro; Serra-Añó, Pilar

2017-10-13

This cross-sectional study analyzed the influence of chronic shoulder pain (CSP) on movement variability/kinematics during humeral elevation, with the trunk and elbow motions constrained to avoid compensatory strategies. For this purpose, 37 volunteers with CSP as the injured group (IG) and 58 participants with asymptomatic shoulders as the control group (CG) participated in the study. Maximum humeral elevation (Emax), maximum angular velocity (Velmax), variability of the maximum angle (CVEmax), functional variability (Func_var), and approximate entropy (ApEn) were calculated from the kinematic data. Patients' pain was measured on the visual analogue scale (VAS). Compared with the CG, the IG presented lower Emax and Velmax and higher variability (i.e., CVEmax, Func_var, and ApEn). Moderate correlations were achieved for the VAS score and the kinematic variables Emax, Velmax and variability of curve analysis, Func_varm, and ApEn. No significant correlation was found for CVEmax. In conclusion, CSP results in a decrease of angle and velocity and an increased shoulder movement variability when the neuromuscular system cannot use compensatory strategies to avoid painful positions.

Insufficient acetabular version increases blood metal ion levels after metal-on-metal hip resurfacing.

PubMed

Hart, Alister J; Skinner, John A; Henckel, Johann; Sampson, Barry; Gordon, Fabiana

2011-09-01

Many factors affect the blood metal ion levels after metal-on-metal (MOM) hip arthroplasty. The main surgically adjustable variable is the amount of coverage of the head provided by the cup which is a function of the inclination and version angles. However, most studies have used plain radiographs which have questionable precision and accuracy, particularly for version and large diameter metal heads; further, these studies do not simultaneously assess version and inclination. Thus the relationship between version and blood metal ions levels has not been resolved. We determined whether cup inclination and version influence blood metal ion levels while adjusting for age at assessment, gender, body mass index, horizontal femoral offset, head size, manufacturer hip type, and Oxford hip score. We prospectively followed 100 individuals (51 females, 49 males) with unilateral MOM hip resurfacing who underwent clinical assessment, CT scanning, and blood metal ion measurement. Multiple regression analysis was used to determine which variables were predictors of blood metal ion levels and to model the effect of these variables. Only cup inclination, version angles, and gender influenced blood cobalt or chromium levels. Cobalt and chromium levels positively correlated with inclination angle and negatively correlated with version angle. The effect of changes in version angle was less than for inclination angle. Based on our observations, we developed a formula to predict the effect of these parameters on metal ion levels. Our data suggest insufficient cup version can cause high blood metal ions after MOM hip arthroplasty. We were unable to show that excessive version caused high levels. Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

The method for measuring the groove density of variable-line-space gratings with elimination of the eccentricity effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Qingbo; Liu, Zhengkun, E-mail: zhkliu@ustc.edu.cn; Chen, Huoyao

2015-02-15

To eliminate the eccentricity effect, a new method for measuring the groove density of a variable-line-space grating was adapted. Based on grating equation, groove density is calculated by measuring the internal angles between zeroth-order and first-order diffracted light for two different wavelengths with the same angle of incidence. The measurement system mainly includes two laser sources, a phase plate, plane mirror, and charge coupled device. The measurement results of a variable-line-space grating demonstrate that the experiment data agree well with theoretical values, and the value of measurement error (ΔN/N) is less than 2.72 × 10{sup −4}.

Complexes of ditopic carbo- and thio-carbohydrazone ligands--mononuclear, 1D chain, dinuclear and tetranuclear examples.

PubMed

Tandon, Santokh S; Dul, Marie-Claire; Lee, John L; Dawe, Louise N; Anwar, Muhammad U; Thompson, Laurence K

2011-04-14

Ligands based on carbo- and thio-carbohydrazone cores, modified with pyridine, carboxylate and oxime ends, have been examined. They display a tautomeric versatility based on the flexible nature of the hydrazone linkages, leading to varied coordination motifs. Examples of mononuclear (Co(II), Ni(II)), dinuclear (Co(III)), 1D chain (Cu(II)) and square [2 × 2] grid (Ni(II)) complexes are obtained. Ferromagnetic (Cu(II)) and antiferromagnetic (Ni(II)) exchange is observed, with spin coupling in the Ni(II)(4) square grids propagated through the μ-O and μ-S bridges. Weak antiferromagnetic exchange (J = -6.0 cm(-1)) is observed for the μ-O bridged grid, despite the large Ni-O-Ni angles (137-141°), while for the μ-S bridged grids much stronger exchange is observed (J = -148 cm(-1), -198 cm(-1)). This is much larger than expected based on the Ni-S-Ni bridge angles (151-169°), and is associated with the soft (less polarizing than oxygen) nature of the sulfur bridge, which would allow for much more efficient transmission of spin exchange than observed in the μ-O bridged case. Structures and variable temperature magnetic data are included, and spin exchange is analyzed using normal Heisenberg exchange models. No examples involving oxime (NO) bridging are reported, which reflects the positioning of the N,O and N,S donor combinations in each ligand, and the preferred coordination through these donor atoms. © The Royal Society of Chemistry 2011

Kinematic functions for the 7 DOF robotics research arm

NASA Technical Reports Server (NTRS)

Kreutz, K.; Long, M.; Seraji, Homayoun

1989-01-01

The Robotics Research Model K-1207 manipulator is a redundant 7R serial link arm with offsets at all joints. To uniquely determine joint angles for a given end-effector configuration, the redundancy is parameterized by a scalar variable which corresponds to the angle between the manipulator elbow plane and the vertical plane. The forward kinematic mappings from joint-space to end-effector configuration and elbow angle, and the augmented Jacobian matrix which gives end-effector and elbow angle rates as a function of joint rates, are also derived.

Solar Cycle Variability Induced by Tilt Angle Scatter in a Babcock-Leighton Solar Dynamo Model

NASA Astrophysics Data System (ADS)

Karak, Bidya Binay; Miesch, Mark

2017-09-01

We present results from a three-dimensional Babcock-Leighton (BL) dynamo model that is sustained by the emergence and dispersal of bipolar magnetic regions (BMRs). On average, each BMR has a systematic tilt given by Joy’s law. Randomness and nonlinearity in the BMR emergence of our model produce variable magnetic cycles. However, when we allow for a random scatter in the tilt angle to mimic the observed departures from Joy’s law, we find more variability in the magnetic cycles. We find that the observed standard deviation in Joy’s law of {σ }δ =15^\\circ produces a variability comparable to the observed solar cycle variability of ˜32%, as quantified by the sunspot number maxima between 1755 and 2008. We also find that tilt angle scatter can promote grand minima and grand maxima. The time spent in grand minima for {σ }δ =15^\\circ is somewhat less than that inferred for the Sun from cosmogenic isotopes (about 9% compared to 17%). However, when we double the tilt scatter to {σ }δ =30^\\circ , the simulation statistics are comparable to the Sun (˜18% of the time in grand minima and ˜10% in grand maxima). Though the BL mechanism is the only source of poloidal field, we find that our simulations always maintain magnetic cycles even at large fluctuations in the tilt angle. We also demonstrate that tilt quenching is a viable and efficient mechanism for dynamo saturation; a suppression of the tilt by only 1°-2° is sufficient to limit the dynamo growth. Thus, any potential observational signatures of tilt quenching in the Sun may be subtle.

Analysis of stresses in finite anisotropic panels with centrally located cutouts

NASA Technical Reports Server (NTRS)

Britt, Vicki O.

1992-01-01

A method for analyzing biaxial- and shear-loaded anisotropic rectangular panels with centrally located circular and elliptical cutouts is presented in the present paper. The method is based on Lekhnitskii's complex variable equations of plane elastostatics combined with a boundary collocation method and a Laurent series approximation. Results are presented for anisotropic panels with elliptical cutouts and subjected to combined shear and compression loading. The effects on the stress field of panel aspect ratio, anisotropy, cutout size, and cutout orientation are addressed. Angle-ply laminates, unidirectional off-axis laminates, and ((+ or - 45/0/90)(sub 3))s, ((+ or - 45/0(sub 2))(sub 3))s, and ((+ or - 45/90(sub 2))(sub 3))s laminates are examined.

Simulation of the Simbol-X Telescope

NASA Astrophysics Data System (ADS)

Chauvin, M.; Roques, J. P.

2009-05-01

We have developed a simulation tool for a Wolter I telescope operating in formation flight. The aim is to understand and predict the behavior of the Simbol-X instrument. As the geometry is variable, formation flight introduces new challenges and complex implications. Our code, based on Monte Carlo ray tracing, computes the full photon trajectories up to the detector plane, along with the relative drifts of the two spacecrafts. It takes into account angle and energy dependent interactions of the photons with the mirrors and applies to any grazing incidence telescope. The resulting images of simulated sources from 0.1 keV to 100 keV allow us to optimize the configuration of the instrument and to assess the performance of the Simbol-X telescope.

Experimental Determination of Infrared Extinction Coefficients of Interplanetary Dust Particles

NASA Technical Reports Server (NTRS)

Spann, J. F., Jr.; Abbas, M. M.

1998-01-01

This technique is based on irradiating a single isolated charged dust particle suspended in balance by an electric field, and measuring the scattered radiation as a function of angle. The observed scattered intensity profile at a specific wavelength obtained for a dust particle of known composition is compared with Mie theory calculations, and the variable parameters relating to the particle size and complex refractive index are adjusted for a best fit between the two profiles. This leads to a simultaneous determination of the particle radius, the complex refractive index, and the scattering and extinction coefficients. The results of these experiments can be utilized to examine the IRAS and DIRBE (Diffuse Infrared Background Experiment) infrared data sets in order to determine the dust particle physical characteristics and distributions by using infrared models and inversion techniques. This technique may also be employed for investigation of the rotational bursting phenomena whereby large size cosmic and interplanetary particles are believed to fragment into smaller dust particles.

Forest height Mapping using the fusion of Lidar and MULTI-ANGLE spectral data

NASA Astrophysics Data System (ADS)

Pang, Y.; Li, Z.

2016-12-01

Characterizing the complexity of forest ecosystem over large area is highly complex. Light detection and Ranging (LIDAR) approaches have demonstrated a high capacity to accurately estimate forest structural parameters. A number of satellite mission concepts have been proposed to fuse LiDAR with other optical imagery allowing Multi-angle spectral observations to be captured using the Bidirectional Reflectance Distribution Function (BRDF) characteristics of forests. China is developing the concept of Chinese Terrestrial Carbon Mapping Satellite. A multi-beam waveform Lidar is the main sensor. A multi-angle imagery system is considered as the spatial mapping sensor. In this study, we explore the fusion potential of Lidar and multi-angle spectral data to estimate forest height across different scales. We flew intensive airborne Lidar and Multi-angle hyperspectral data in Genhe Forest Ecological Research Station, Northeast China. Then extended the spatial scale with some long transect flights to cover more forest structures. Forest height data derived from airborne lidar data was used as reference data and the multi-angle hyperspectral data was used as model inputs. Our results demonstrate that the multi-angle spectral data can be used to estimate forest height with the RMSE of 1.1 m with an R2 approximately 0.8.

Motion of the angular momentum vector in body coordinates for torque-free dual-spin spacecraft

NASA Technical Reports Server (NTRS)

Fedor, J. V.

1981-01-01

The motion of the angular momentum vector in body coordinates for torque free, asymmetric dual spin spacecraft without and, for a special case, with energy dissipation on the main spacecraft is investigated. Without energy dissipation, two integrals can be obtained from the Euler equations of motion. Using the classical method of elimination of variable, the motion about the equilibrium points (six for the general case) are derived with these integrals. For small nutation angle, theta, the trajectories about the theta = 0 deg and theta = 180 deg points readily show the requirements for stable motion about these points. Also the conditions needed to eliminate stable motion about the theta = 180 deg point as well as the other undesireable equilibrium points follow directly from these equations. For the special case where the angular momentum vector moves about the principal axis which contains the momentum wheel, the notion of 'free variable' azimuth angle is used. Physically this angle must vary from 0 to 2 pi in a circular periodic fashion. Expressions are thus obtained for the nutation angle in terms of the free variable and other spacecraft parameters. Results show that in general there are two separate trajectory expressions that govern the motion of the angular momentum vector in body coordinates.

Twisted MoSe 2 bilayers with variable local stacking and interlayer coupling revealed by low-frequency Raman spectroscopy

DOE PAGES

Puretzky, Alexander A.; Liang, Liangbo; Li, Xufan; ...

2016-01-14

Unique twisted bilayers of MoSe 2 with multiple stacking orientations and interlayer couplings in the narrow range of twist angles, 60 ± 3°, are revealed by low-frequency Raman spectroscopy and theoretical analysis. The slight deviation from 60 allows the concomitant presence of patches featuring all three high-symmetry stacking configurations (2H or AA', AB', A'B) in one unique bilayer system. In this case, the periodic arrangement of the patches and their size strongly depend on the twist angle. Ab initio modeling predicts significant changes in frequencies and intensities of low-frequency modes versus stacking and twist angle. Experimentally, the variable stacking andmore » coupling across the interface is revealed by the appearance of two breathing modes corresponding to the mixture of the high-symmetry stacking configurations and unaligned regions of monolayers. Only one breathing mode is observed outside the narrow range of twist angles. This indicates a stacking transition to unaligned monolayers with mismatched atom registry without the in-plane restoring force required to generate a shear mode. As a result, the variable interlayer coupling and spacing in transition metal dichalcogenide bilayers revealed in this study may provide a new platform for optoelectronic applications of these materials.« less

Twisted MoSe 2 bilayers with variable local stacking and interlayer coupling revealed by low-frequency Raman spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puretzky, Alexander A.; Liang, Liangbo; Li, Xufan

Unique twisted bilayers of MoSe 2 with multiple stacking orientations and interlayer couplings in the narrow range of twist angles, 60 ± 3°, are revealed by low-frequency Raman spectroscopy and theoretical analysis. The slight deviation from 60 allows the concomitant presence of patches featuring all three high-symmetry stacking configurations (2H or AA', AB', A'B) in one unique bilayer system. In this case, the periodic arrangement of the patches and their size strongly depend on the twist angle. Ab initio modeling predicts significant changes in frequencies and intensities of low-frequency modes versus stacking and twist angle. Experimentally, the variable stacking andmore » coupling across the interface is revealed by the appearance of two breathing modes corresponding to the mixture of the high-symmetry stacking configurations and unaligned regions of monolayers. Only one breathing mode is observed outside the narrow range of twist angles. This indicates a stacking transition to unaligned monolayers with mismatched atom registry without the in-plane restoring force required to generate a shear mode. As a result, the variable interlayer coupling and spacing in transition metal dichalcogenide bilayers revealed in this study may provide a new platform for optoelectronic applications of these materials.« less

Topography of Cells Revealed by Variable-Angle Total Internal Reflection Fluorescence Microscopy.

PubMed

Cardoso Dos Santos, Marcelina; Déturche, Régis; Vézy, Cyrille; Jaffiol, Rodolphe

2016-09-20

We propose an improved version of variable-angle total internal reflection fluorescence microscopy (vaTIRFM) adapted to modern TIRF setup. This technique involves the recording of a stack of TIRF images, by gradually increasing the incident angle of the light beam on the sample. A comprehensive theory was developed to extract the membrane/substrate separation distance from fluorescently labeled cell membranes. A straightforward image processing was then established to compute the topography of cells with a nanometric axial resolution, typically 10-20 nm. To highlight the new opportunities offered by vaTIRFM to quantify adhesion process of motile cells, adhesion of MDA-MB-231 cancer cells on glass substrate coated with fibronectin was examined. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Integrability of geodesics and action-angle variables in Sasaki-Einstein space T^{1,1}

NASA Astrophysics Data System (ADS)

Visinescu, Mihai

2016-09-01

We briefly describe the construction of Stäkel-Killing and Killing-Yano tensors on toric Sasaki-Einstein manifolds without working out intricate generalized Killing equations. The integrals of geodesic motions are expressed in terms of Killing vectors and Killing-Yano tensors of the homogeneous Sasaki-Einstein space T^{1,1}. We discuss the integrability of geodesics and construct explicitly the action-angle variables. Two pairs of frequencies of the geodesic motions are resonant giving way to chaotic behavior when the system is perturbed.

Preliminary biplane tests in the variable density wind tunnel

NASA Technical Reports Server (NTRS)

Shoemaker, James M

1928-01-01

Biplane cellules using the N.A.C.A.-M6 airfoil section have been tested in the variable density wind tunnel of the National Advisory Committee for Aeronautics. Three cellules, differing only in the amount of stagger, were tested at two air densities, corresponding to pressures of one atmosphere and of twenty atmospheres. The range of angle of attack was from -2 degrees to +48 degrees. The effect of stagger on the lift and drag, and on the shielding effect of the upper wing by the lower at high angles of attack was determined.

Quasi-cylindrical theory of wing-body interference at supersonic speeds and comparison with experiment

NASA Technical Reports Server (NTRS)

Nielsen, Jack N

1955-01-01

A theoretical method is presented for calculating the flow field about wing-body combinations employing bodies deviating only slightly in shape from a circular cylinder. The method is applied to the calculation of the pressure field acting between a circular cylindrical body and a rectangular wing. The case of zero body angle of attack and variable wing incidence is considered as well as the case of zero wing incidence and variable body angle of attack. An experiment was performed especially for the purpose of checking the calculative examples.

Simulating variable source problems via post processing of individual particle tallies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bleuel, D.L.; Donahue, R.J.; Ludewigt, B.A.

2000-10-20

Monte Carlo is an extremely powerful method of simulating complex, three dimensional environments without excessive problem simplification. However, it is often time consuming to simulate models in which the source can be highly varied. Similarly difficult are optimization studies involving sources in which many input parameters are variable, such as particle energy, angle, and spatial distribution. Such studies are often approached using brute force methods or intelligent guesswork. One field in which these problems are often encountered is accelerator-driven Boron Neutron Capture Therapy (BNCT) for the treatment of cancers. Solving the reverse problem of determining the best neutron source formore » optimal BNCT treatment can be accomplished by separating the time-consuming particle-tracking process of a full Monte Carlo simulation from the calculation of the source weighting factors which is typically performed at the beginning of a Monte Carlo simulation. By post-processing these weighting factors on a recorded file of individual particle tally information, the effect of changing source variables can be realized in a matter of seconds, instead of requiring hours or days for additional complete simulations. By intelligent source biasing, any number of different source distributions can be calculated quickly from a single Monte Carlo simulation. The source description can be treated as variable and the effect of changing multiple interdependent source variables on the problem's solution can be determined. Though the focus of this study is on BNCT applications, this procedure may be applicable to any problem that involves a variable source.« less

Effects of macromolecular crowding on the structure of a protein complex: A small-angle scattering study of superoxide dismutase

DOE PAGES

Rajapaksha, Ajith; Stanley, Christopher B.; Todd, Brian A.

2015-02-17

Macromolecular crowding can alter the structure and function of biological macromolecules. We used small angle scattering (SAS) to measure the change in size of a protein complex, superoxide dismutase (SOD), induced by macromolecular crowding. Crowding was induced using 400 MW polyethylene glycol (PEG), triethylene glycol (TEG), methyl- -glucoside ( -MG) and trimethylamine N-oxide (TMAO). Parallel small angle neutron scattering (SANS) and small angle x-ray scattering (SAXS) allowed us to unambiguously attribute apparent changes in radius of gyration to changes in the structure of SOD. For a 40% PEG solution, we find that the volume of SOD was reduced by 9%.more » Considering the osmotic pressure due to PEG, this deformation corresponds to a highly compressible structure. SAXS done in the presence of TEG suggests that for further deformation beyond a 9% decrease in volume the resistance to deformation may increase dramatically.« less

Centre-based restricted nearest feature plane with angle classifier for face recognition

NASA Astrophysics Data System (ADS)

Tang, Linlin; Lu, Huifen; Zhao, Liang; Li, Zuohua

2017-10-01

An improved classifier based on the nearest feature plane (NFP), called the centre-based restricted nearest feature plane with the angle (RNFPA) classifier, is proposed for the face recognition problems here. The famous NFP uses the geometrical information of samples to increase the number of training samples, but it increases the computation complexity and it also has an inaccuracy problem coursed by the extended feature plane. To solve the above problems, RNFPA exploits a centre-based feature plane and utilizes a threshold of angle to restrict extended feature space. By choosing the appropriate angle threshold, RNFPA can improve the performance and decrease computation complexity. Experiments in the AT&T face database, AR face database and FERET face database are used to evaluate the proposed classifier. Compared with the original NFP classifier, the nearest feature line (NFL) classifier, the nearest neighbour (NN) classifier and some other improved NFP classifiers, the proposed one achieves competitive performance.

The Asymmetrical Wind of the Candidate Luminous Blue Variable MWC 314

NASA Technical Reports Server (NTRS)

Wisniewski, John P.; Babler, Brian L.; Bjorkman, Karen S.; Kurchakov, Anatoly V.; Meade,Marilyn R.; Miroshnichenko, Anatoly S.

2006-01-01

We present the results of long-term spectropolarimetric and spectroscopic monitoring of MWC 314, a candidate Luminous Blue Variable star. We detect the first evidence of H alpha variability in MWC 314, and find no apparent periodicity in this emission. The total R-band polarization is observed to vary between 2.21% and 3.00% at a position angle consistently around approximately 0 degrees, indicating the presence of a time-variable intrinsic polarization component, hence an asymmetrical circumstellar envelope. We find suggestive evidence that MWC 314's intrinsic polarization exhibits a wavelength-independent magnitude varying between 0.09% and 0.58% at a wavelength-independent position angle covering all four quadrants of the Stokes Q-U plane. Electron scattering off of density clumps in MWC 314's wind is considered as the probable mechanism responsible for these variations.

Morphological configuration of the cranial base among children aged 8 to 12 years.

PubMed

Cossio, Lina; López, Jorge; Rueda, Zulma Vanessa; Botero-Mariaca, Paola

2016-06-14

Cranial base is used as reference structure to determine the skeletal type in cephalometric analysis. The purpose was to assess the cranial base length on lateral cephalic radiographs of children between 8 and 12 and compare these measurements with baseline studies in order to evaluate the relationship between the length and the cranial base angle, articular angle, gonial angle and skeletal type. A Cross-sectional study in 149 children aged 8-12 years, originally from Aburrá Valley, who had lateral cephalic radiographs and consented to participate in this study. The variables studied included: age, sex, sella-nasion, sella-nasion-articular, sella-nasion-basion, articular-gonion-menton, gonion-menton, sella-nasion-point B, sella-nasion-point A y point A-nasion-point B. These variables were digitally measured through i-dixel 2 digital software. One-way ANOVA was used to determine mean values and mean value differences. The values obtained were compared with previous studies. A p value <0.05 was considered significant. Cranial base lengths are smaller in each age and sex group, with differences exceeding 10 mm for measurement, compared both with the study by Riolo (Michigan) and the study carried out in Damasco (Antioquia). No relation was found between the skeletal type and the anterior cranial base length, the sella angle and the cranial base angle. Also, no relation was found between the gonial angle and sella angle or the cranial base angle. The cranial base varies from one population to another. Accordingly, compared to other studies it is shorter for the assessed sample.

Aerosol Optical Depth Retrievals from High-Resolution Commercial Satellite Imagery Over Areas of High Surface Reflectance

DTIC Science & Technology

2006-06-01

angle Imaging SpectroRadiometer MODIS Moderate Resolution Imaging Spectroradiometer NGA National Geospatial Intelligence Agency POI Principles of...and µ , the cosine of the viewing zenith angle and the effect of the variation of each of these variables on total optical depth. Extraterrestrial ...Eq. (34). Additionally, solar zenith angle also plays a role in the third term on the RHS of Eq. (34) by modifying extraterrestrial spectral solar

Argon laser peripheral iridoplasty for angle-closure glaucoma in sibilings with weill-marchesani syndrome.

PubMed

Ritch, R; Solomon, L D

1992-01-01

A patient with Weill-Marchesani syndrome and angle-closure glaucoma had persistent appositional closure after laser iridotomy that was unrelieved by topical application of either miotic or cycloplegic agents. Argon laser peripheral iridoplasty successfully opened the angle. The patient's sister also had Weill-Marchesani syndrome and angle closure unrelieved by laser iridotomy. Angle closure in Weill-Marchesani syndrome and the response to laser iridotomy and treatment with either miotic or cycloplegic agents may be complex and depends on the relative proportion of pupillary block as a mechanism underlying the angle closure, the functional status of the zonular apparatus, and the degree of angle crowding by the peripheral iris in the presence or absence of peripheral anterior synechiae.

Improving the efficiency of configurational-bias Monte Carlo: A density-guided method for generating bending angle trials for linear and branched molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sepehri, Aliasghar; Loeffler, Troy D.; Chen, Bin, E-mail: binchen@lsu.edu

2014-08-21

A new method has been developed to generate bending angle trials to improve the acceptance rate and the speed of configurational-bias Monte Carlo. Whereas traditionally the trial geometries are generated from a uniform distribution, in this method we attempt to use the exact probability density function so that each geometry generated is likely to be accepted. In actual practice, due to the complexity of this probability density function, a numerical representation of this distribution function would be required. This numerical table can be generated a priori from the distribution function. This method has been tested on a united-atom model ofmore » alkanes including propane, 2-methylpropane, and 2,2-dimethylpropane, that are good representatives of both linear and branched molecules. It has been shown from these test cases that reasonable approximations can be made especially for the highly branched molecules to reduce drastically the dimensionality and correspondingly the amount of the tabulated data that is needed to be stored. Despite these approximations, the dependencies between the various geometrical variables can be still well considered, as evident from a nearly perfect acceptance rate achieved. For all cases, the bending angles were shown to be sampled correctly by this method with an acceptance rate of at least 96% for 2,2-dimethylpropane to more than 99% for propane. Since only one trial is required to be generated for each bending angle (instead of thousands of trials required by the conventional algorithm), this method can dramatically reduce the simulation time. The profiling results of our Monte Carlo simulation code show that trial generation, which used to be the most time consuming process, is no longer the time dominating component of the simulation.« less

[Analysis of Conformational Features of Watson-Crick Duplex Fragments by Molecular Mechanics and Quantum Mechanics Methods].

PubMed

Poltev, V I; Anisimov, V M; Sanchez, C; Deriabina, A; Gonzalez, E; Garcia, D; Rivas, F; Polteva, N A

2016-01-01

It is generally accepted that the important characteristic features of the Watson-Crick duplex originate from the molecular structure of its subunits. However, it still remains to elucidate what properties of each subunit are responsible for the significant characteristic features of the DNA structure. The computations of desoxydinucleoside monophosphates complexes with Na-ions using density functional theory revealed a pivotal role of DNA conformational properties of single-chain minimal fragments in the development of unique features of the Watson-Crick duplex. We found that directionality of the sugar-phosphate backbone and the preferable ranges of its torsion angles, combined with the difference between purines and pyrimidines. in ring bases, define the dependence of three-dimensional structure of the Watson-Crick duplex on nucleotide base sequence. In this work, we extended these density functional theory computations to the minimal' fragments of DNA duplex, complementary desoxydinucleoside monophosphates complexes with Na-ions. Using several computational methods and various functionals, we performed a search for energy minima of BI-conformation for complementary desoxydinucleoside monophosphates complexes with different nucleoside sequences. Two sequences are optimized using ab initio method at the MP2/6-31++G** level of theory. The analysis of torsion angles, sugar ring puckering and mutual base positions of optimized structures demonstrates that the conformational characteristic features of complementary desoxydinucleoside monophosphates complexes with Na-ions remain within BI ranges and become closer to the corresponding characteristic features of the Watson-Crick duplex crystals. Qualitatively, the main characteristic features of each studied complementary desoxydinucleoside monophosphates complex remain invariant when different computational methods are used, although the quantitative values of some conformational parameters could vary lying within the limits typical for the corresponding family. We observe that popular functionals in density functional theory calculations lead to the overestimated distances between base pairs, while MP2 computations and the newer complex functionals produce the structures that have too close atom-atom contacts. A detailed study of some complementary desoxydinucleoside monophosphate complexes with Na-ions highlights the existence of several energy minima corresponding to BI-conformations, in other words, the complexity of the relief pattern of the potential energy surface of complementary desoxydinucleoside monophosphate complexes. This accounts for variability of conformational parameters of duplex fragments with the same base sequence. Popular molecular mechanics force fields AMBER and CHARMM reproduce most of the conformational characteristics of desoxydinucleoside monophosphates and their complementary complexes with Na-ions but fail to reproduce some details of the dependence of the Watson-Crick duplex conformation on the nucleotide sequence.

Computer programs for the calculation of dual sting pitch and roll angles required for an articulated sting to obtain angles of attack and sideslip on wind-tunnel models

NASA Technical Reports Server (NTRS)

Peterson, John B., Jr.

1991-01-01

Two programs were developed to calculate the pitch and roll position of the conventional sting drive and the pitch of a high angle articulated sting to position a wind tunnel model at the desired angle of attack and sideslip and position the model as near as possible to the centerline of the tunnel. These programs account for the effects of sting offset angles, sting bending angles, and wind-tunnel stream flow angles. In addition, the second program incorporates inputs form on-board accelerometers that measure model pitch and roll with respect to gravity. The programs are presented and a description of the numerical operation of the programs with a definition of the variables used in the programs is given.

Geometry and Kinematics of Fault-Propagation Folds with Variable Interlimb Angles

NASA Astrophysics Data System (ADS)

Dhont, D.; Jabbour, M.; Hervouet, Y.; Deroin, J.

2009-12-01

Fault-propagation folds are common features in foreland basins and fold-and-thrust belts. Several conceptual models have been proposed to account for their geometry and kinematics. It is generally accepted that the shape of fault-propagation folds depends directly from both the amount of displacement along the basal decollement level and the dip angle of the ramp. Among these, the variable interlimb angle model proposed by Mitra (1990) is based on a folding kinematics that is able to explain open and close natural folds. However, the application of this model is limited because the geometric evolution and thickness variation of the fold directly depend on imposed parameters such as the maximal value of the ramp height. Here, we use the ramp and the interlimb angles as input data to develop a forward fold modelling accounting for thickness variations in the forelimb. The relationship between the fold amplitude and fold wavelength are subsequently applied to build balanced geologic cross-sections from surface parameters only, and to propose a kinematic restoration of the folding through time. We considered three natural examples to validate the variable interlimb angle model. Observed thickness variations in the forelimb of the Turner Valley anticline in the Alberta foothills of Canada precisely correspond to the theoretical values proposed by our model. Deep reconstruction of the Alima anticline in the southern Tunisian Atlas implies that the decollement level is localized in the Triassic-Liassic series, as highlighted by seismic imaging. Our kinematic reconstruction of the Ucero anticline in the Spanish Castilian mountains is also in agreement with the anticline geometry derived from two cross-sections. The variable interlimb angle model implies that the fault-propagation fold can be symmetric, normal asymmetric (with a greater dip value in the forelimb than in the backlimb), or reversely asymmetric (with greater dip in the backlimb) depending on the shortening amount. This model allows also: (i) to easily explain folds with wide variety of geometries; (ii) to understand the deep architecture of anticlines; and (iii) to deduce the kinematic evolution of folding with time. Mitra, S., 1990, Fault-propagation folds: geometry, kinematic evolution, and hydrocarbon traps. AAPG Bulletin, v. 74, no. 6, p. 921-945.

Correlating contact line capillarity and dynamic contact angle hysteresis in surfactant-nanoparticle based complex fluids

NASA Astrophysics Data System (ADS)

Harikrishnan, A. R.; Dhar, Purbarun; Agnihotri, Prabhat K.; Gedupudi, Sateesh; Das, Sarit K.

2018-04-01

Dynamic wettability and contact angle hysteresis can be correlated to shed insight onto any solid-liquid interaction. Complex fluids are capable of altering the expected hysteresis and dynamic wetting behavior due to interfacial interactions. We report the effect of capillary number on the dynamic advancing and receding contact angles of surfactant-based nanocolloidal solutions on hydrophilic, near hydrophobic, and superhydrophobic surfaces by performing forced wetting and de-wetting experiments by employing the embedded needle method. A segregated study is performed to infer the contributing effects of the constituents and effects of particle morphology. The static contact angle hysteresis is found to be a function of particle and surfactant concentrations and greatly depends on the nature of the morphology of the particles. An order of estimate of line energy and a dynamic flow parameter called spreading factor and the transient variations of these parameters are explored which sheds light on the dynamics of contact line movement and response to perturbation of three-phase contact. The Cox-Voinov-Tanner law was found to hold for hydrophilic and a weak dependency on superhydrophobic surfaces with capillary number, and even for the complex fluids, with a varying degree of dependency for different fluids.

Empirical Models for the Shielding and Reflection of Jet Mixing Noise by a Surface

NASA Technical Reports Server (NTRS)

Brown, Cliff

2015-01-01

Empirical models for the shielding and refection of jet mixing noise by a nearby surface are described and the resulting models evaluated. The flow variables are used to non-dimensionalize the surface position variables, reducing the variable space and producing models that are linear function of non-dimensional surface position and logarithmic in Strouhal frequency. A separate set of coefficients are determined at each observer angle in the dataset and linear interpolation is used to for the intermediate observer angles. The shielding and rejection models are then combined with existing empirical models for the jet mixing and jet-surface interaction noise sources to produce predicted spectra for a jet operating near a surface. These predictions are then evaluated against experimental data.

Empirical Models for the Shielding and Reflection of Jet Mixing Noise by a Surface

NASA Technical Reports Server (NTRS)

Brown, Clifford A.

2016-01-01

Empirical models for the shielding and reflection of jet mixing noise by a nearby surface are described and the resulting models evaluated. The flow variables are used to non-dimensionalize the surface position variables, reducing the variable space and producing models that are linear function of non-dimensional surface position and logarithmic in Strouhal frequency. A separate set of coefficients are determined at each observer angle in the dataset and linear interpolation is used to for the intermediate observer angles. The shielding and reflection models are then combined with existing empirical models for the jet mixing and jet-surface interaction noise sources to produce predicted spectra for a jet operating near a surface. These predictions are then evaluated against experimental data.

Improved imaging of cochlear nerve hypoplasia using a 3-Tesla variable flip-angle turbo spin-echo sequence and a 7-cm surface coil.

PubMed

Giesemann, Anja M; Raab, Peter; Lyutenski, Stefan; Dettmer, Sabine; Bültmann, Eva; Frömke, Cornelia; Lenarz, Thomas; Lanfermann, Heinrich; Goetz, Friedrich

2014-03-01

Magnetic resonance imaging of the temporal bone has an important role in decision making with regard to cochlea implantation, especially in children with cochlear nerve deficiency. The purpose of this study was to evaluate the usefulness of the combination of an advanced high-resolution T2-weighted sequence with a surface coil in a 3-Tesla magnetic resonance imaging scanner in cases of suspected cochlear nerve aplasia. Prospective study. Seven patients with cochlear nerve hypoplasia or aplasia were prospectively examined using a high-resolution three-dimensional variable flip-angle turbo spin-echo sequence using a surface coil, and the images were compared with the same sequence in standard resolution using a standard head coil. Three neuroradiologists evaluated the magnetic resonance images independently, rating the visibility of the nerves in diagnosing hypoplasia or aplasia. Eight ears in seven patients with hypoplasia or aplasia of the cochlear nerve were examined. The average age was 2.7 years (range, 9 months-5 years). Seven ears had accompanying malformations. The inter-rater reliability in diagnosing hypoplasia or aplasia was greater using the high-resolution three-dimensional variable flip-angle turbo spin-echo sequence (fixed-marginal kappa: 0.64) than with the same sequence in lower resolution (fixed-marginal kappa: 0.06). Examining cases of suspected cochlear nerve aplasia using the high-resolution three-dimensional variable flip-angle turbo spin-echo sequence in combination with a surface coil shows significant improvement over standard methods. © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

Inter- and intra-observer variability of radiography and computed tomography for evaluation of Zurich cementless acetabular cup placement ex vivo.

PubMed

Leasure, Jessica O; Peck, Jeffrey N; Villamil, Armando; Fiore, Kara L; Tano, Cheryl A

2016-11-23

To evaluate the inter- and intra-observer variability in measurement of the angle of lateral opening (ALO) and version angle measurement using digital radiography and computed tomography (CT). Each hemipelvis was implanted with a cementless acetabular cup. Ventrodorsal and mediolateral radiographs were made of each pelvis, followed by CT imaging. After removal of the first cup, the pelves were implanted with an acetabular cup in the contralateral acetabulum and imaging was repeated. Three surgeons measured the ALO and version angles three times for each cup from the mediolateral radiographic projection. The same measurements were made using three-dimensional multiplanar reconstructions from CT images. Two anatomical axes were used to measure pelvic inclination in the sagittal plane, resulting in six measurements per cup. Two-way repeated measures analysis of variance evaluated inter- and intra-observer repeatability for radiographic and CT-based measurements. Version angle based on radiographic measurement did not differ within surgeons (p = 0.433), but differed between surgeons (p <0.001). Radiographic measurement of ALO differed within surgeons (p = 0.006) but not between surgeons (p = 0.989). The ALO and version angle measured on CT images did not differ with or between surgeons. Assessment of inter- and intra-observer measurement of ALO and version angle was more reproducible using CT images than conventional mediolateral radiography for a Zurich cementless acetabular cup.

Variability of phase and amplitude fronts due to horizontal refraction in shallow water.

PubMed

Katsnelson, Boris G; Grigorev, Valery A; Lynch, James F

2018-01-01

The variability of the interference pattern of a narrow-band sound signal in a shallow water waveguide in the horizontal plane in the presence of horizontal stratification, in particular due to linear internal waves, is studied. It is shown that lines of constant phase (a phase front) and lines of constant amplitude/envelope (an amplitude front) for each waveguide mode may have different directions in the spatial vicinity of the point of reception. The angle between them depends on the waveguide's parameters, the mode number, and the sound frequency. Theoretical estimates and data processing methodology for obtaining these angles from experimental data recorded by a horizontal line array are proposed. The behavior of the angles, which are obtained for two episodes from the Shallow Water 2006 (SW06) experiment, show agreement with the theory presented.

Shuttle program: Ground tracking data program document shuttle OFT launch/landing

NASA Technical Reports Server (NTRS)

Lear, W. M.

1977-01-01

The equations for processing ground tracking data during a space shuttle ascent or entry, or any nonfree flight phase of a shuttle mission are given. The resulting computer program processes data from up to three stations simultaneously: C-band station number 1; C-band station number 2; and an S-band station. The C-band data consists of range, azimuth, and elevation angle measurements. The S-band data consists of range, two angles, and integrated Doppler data in the form of cycle counts. A nineteen element state vector is used in Kalman filter to process the measurements. The acceleration components of the shuttle are taken to be independent exponentially-correlated random variables. Nine elements of the state vector are the measurement bias errors associated with range and two angles for each tracking station. The biases are all modeled as exponentially-correlated random variables with a typical time constant of 108 seconds. All time constants are taken to be the same for all nine state variables. This simplifies the logic in propagating the state error covariance matrix ahead in time.

Physically-based model of soil hydraulic properties accounting for variable contact angle and its effect on hysteresis

NASA Astrophysics Data System (ADS)

Diamantopoulos, Efstathios; Durner, Wolfgang

2013-09-01

The description of soil water movement in the unsaturated zone requires the knowledge of the soil hydraulic properties, i.e. the water retention and the hydraulic conductivity function. A great amount of parameterizations for this can be found in the literature, the majority of which represent the complex pore space of soils as a bundle of cylindrical capillary tubes of various sizes. The assumption of zero contact angles between water and surface of the grains is also made. However, these assumptions limit the predictive capabilities of these models, leading often to errors in the prediction of water dynamics in soils. We present a pore-scale analysis for equilibrium liquid configuration in angular pores taking pore-scale hysteresis and the effect of contact angle into account. Furthermore, we propose a derivation of the hydraulic conductivity function, again as a function of the contact angle. An additional parameter was added to the conductivity function in order take into account effects which are not included in the analysis. Finally, we upscale our model from the pore to the sample scale by assuming a gamma statistical distribution of the pore sizes. Closed-form expressions are derived for both water retention and conductivity functions. The new model was tested against experimental data from multistep inflow/outflow (MSI/MSO) experiments for a sandy material. They were conducted using ethanol and water as the wetting liquid. Ethanol was assumed to form a zero contact angle with the soil grains. By keeping constant the parameters fitted from the ethanol MSO experiment we could predict the ethanol MSI dynamics based on our theory. Furthermore, by keeping constant the pore size distribution parameters from the ethanol experiments we could also predict very well the water dynamics for the MSO experiment. Lastly, we could predict the imbibition dynamics for the water MSI experiment by introducing a finite value of the contact angle. Most importantly, the predictions for both ethanol and water MSI/MSO dynamics were made by assuming a unique pore-size distribution.

Native Tandem and Ion Mobility Mass Spectrometry Highlight Structural and Modular Similarities in Clustered-Regularly-Interspaced Shot-Palindromic-Repeats (CRISPR)-associated Protein Complexes From Escherichia coli and Pseudomonas aeruginosa*

PubMed Central

van Duijn, Esther; Barbu, Ioana M.; Barendregt, Arjan; Jore, Matthijs M.; Wiedenheft, Blake; Lundgren, Magnus; Westra, Edze R.; Brouns, Stan J. J.; Doudna, Jennifer A.; van der Oost, John; Heck, Albert J. R.

2012-01-01

The CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR-associated genes) immune system of bacteria and archaea provides acquired resistance against viruses and plasmids, by a strategy analogous to RNA-interference. Key components of the defense system are ribonucleoprotein complexes, the composition of which appears highly variable in different CRISPR/Cas subtypes. Previous studies combined mass spectrometry, electron microscopy, and small angle x-ray scattering to demonstrate that the E. coli Cascade complex (405 kDa) and the P. aeruginosa Csy-complex (350 kDa) are similar in that they share a central spiral-shaped hexameric structure, flanked by associating proteins and one CRISPR RNA. Recently, a cryo-electron microscopy structure of Cascade revealed that the CRISPR RNA molecule resides in a groove of the hexameric backbone. For both complexes we here describe the use of native mass spectrometry in combination with ion mobility mass spectrometry to assign a stable core surrounded by more loosely associated modules. Via computational modeling subcomplex structures were proposed that relate to the experimental IMMS data. Despite the absence of obvious sequence homology between several subunits, detailed analysis of sub-complexes strongly suggests analogy between subunits of the two complexes. Probing the specific association of E. coli Cascade/crRNA to its complementary DNA target reveals a conformational change. All together these findings provide relevant new information about the potential assembly process of the two CRISPR-associated complexes. PMID:22918228

Research on damping properties optimization of variable-stiffness plate

NASA Astrophysics Data System (ADS)

Wen-kai, QI; Xian-tao, YIN; Cheng, SHEN

2016-09-01

This paper investigates damping optimization design of variable-stiffness composite laminated plate, which means fibre paths can be continuously curved and fibre angles are distinct for different regions. First, damping prediction model is developed based on modal dissipative energy principle and verified by comparing with modal testing results. Then, instead of fibre angles, the element stiffness and damping matrixes are translated to be design variables on the basis of novel Discrete Material Optimization (DMO) formulation, thus reducing the computation time greatly. Finally, the modal damping capacity of arbitrary order is optimized using MMA (Method of Moving Asymptotes) method. Meanwhile, mode tracking technique is employed to investigate the variation of modal shape. The convergent performance of interpolation function, first order specific damping capacity (SDC) optimization results and variation of modal shape in different penalty factor are discussed. The results show that the damping properties of the variable-stiffness plate can be increased by 50%-70% after optimization.

Reliability of tunnel angle in ACL reconstruction: two-dimensional versus three-dimensional guide technique.

PubMed

Leiter, Jeff R S; de Korompay, Nevin; Macdonald, Lindsey; McRae, Sheila; Froese, Warren; Macdonald, Peter B

2011-08-01

To compare the reliability of tibial tunnel position and angle produced with a standard ACL guide (two-dimensional guide) or Howell 65° Guide (three-dimensional guide) in the coronal and sagittal planes. In the sagittal plane, the dependent variables were the angle of the tibial tunnel relative to the tibial plateau and the position of the tibial tunnel with respect to the most posterior aspect of the tibia. In the coronal plane, the dependent variables were the angle of the tunnel with respect to the medial joint line of the tibia and the medial and lateral placement of the tibial tunnel relative to the most medial aspect of the tibia. The position and angle of the tibial tunnel in the coronal and sagittal planes were determined from anteroposterior and lateral radiographs, respectively, taken 2-6 months postoperatively. The two-dimensional and three-dimensional guide groups included 28 and 24 sets of radiographs, respectively. Tibial tunnel position was identified, and tunnel angle measurements were completed. Multiple investigators measured the position and angle of the tunnel 3 times, at least 7 days apart. The angle of the tibial tunnel in the coronal plane using a two-dimensional guide (61.3 ± 4.8°) was more horizontal (P < 0.05) than tunnels drilled with a three-dimensional guide (64.7 ± 6.2°). The position of the tibial tunnel in the sagittal plane was more anterior (P < 0.05) in the two-dimensional (41.6 ± 2.5%) guide group compared to the three-dimensional guide group (43.3 ± 2.9%). The Howell Tibial Guide allows for reliable placement of the tibial tunnel in the coronal plane at an angle of 65°. Tibial tunnels were within the anatomical footprint of the ACL with either technique. Future studies should investigate the effects of tibial tunnel angle on knee function and patient quality of life. Case-control retrospective comparative study, Level III.

Factors Contributing to Pelvis Instability in Female Adolescent Athletes During Unilateral Repeated Partial Squat Activity

PubMed Central

Scarborough, Donna Moxley; Linderman, Shannon; Berkson, Eric M.; Oh, Luke S.

2017-01-01

Objectives: Unilateral partial squat tasks are often used to assess athletes’ lower extremity (LE) neuromuscular control. Single squat biomechanics such as lateral drop of the non-stance limb’s pelvis have been linked to knee injury risk. Yet, there are limited studies on the factors contributing to pelvic instability during the unilateral partial squat such as anatomical alignment of the knee and hip strength. The purpose of this study was 1) to assess the influence of leg dominance on pelvic drop among female athletes during the repeated unilateral partial squat activity and 2) to investigate the contributions that lower limb kinematics and hip strength have on pelvis drop. Methods: 42 female athletes (27= softball pitchers, 15=gymnasts, avg age=16.48 ± 2.54 years) underwent lower limb assessment. The quadriceps angle (Q angle) and the average of 3 trials for hip abduction and extension strength (handheld dynamometer measurements) were used for analyses. 3D biomechanical analysis of the repeated unilateral partial squat activity followed using a 20 motion capture camera system which created a 15 segment model of each subject. The subject stood on one leg at the lateral edge of a 17.78 cm box with hands placed on the hips and squatted so that the free hanging contralateral limb came as close to the ground without contact for 5 continuous repetitions. One trial for each limb was performed. Peak pelvic drop and ankle, knee and hip angles and torques (normalized by weight) at this time point were calculated using Visual 3D (C-Motion) biomechanical software. Paired T-test, Spearman correlations and multiple regression model statistical analyses were performed. Results: Peak pelvic drop during the unilateral partial squat did not differ significantly on the basis of limb dominance (p=0.831, Dom: -3.40 ± 5.10° , ND: -3.46 ± 4.44°). Peak pelvic drop displayed a Spearman correlation with the functional measure of hip abduction/adduction (ABD/ADD) angle (rs= 0.627, p< 0.001) (Figure 1). No association was noted between peak pelvic drop and anatomical measures of Q angle or isometric hip extension strength. A multiple regression was performed to predict pelvis drop angle from the following 6 variables: isometric hip ABD strength, hip ABD/ADD angle, hip internal/external rotation angle, ankle supination/pronation (S/P) angle, height and weight. These variables statistically predicted pelvis drop, F(6,73) = 17.848, p < .0005, R2 = 0.595. The strongest combined predictor variables for pelvic drop in the female athletes were hip abduction/ adduction angle and strength followed by subject’s weight and ankle S/P angle (Table 1). Conclusion: Peak pelvic drop during the repeated unilateral partial squat activity did not correlate significantly with Q angle and hip extension strength. Instead, peak pelvic drop appears more related to a combination of biomechanical limb positioning, hip ABD strength and subject demographics. The regression model run on the repeated unilateral partial squat demonstrates predictive power of this dynamic assessment tool based on kinematic measures across multiple joints. Results could guide clinician screening for excessive pelvic drop in female athletes and based on the predictive model make recommendations for corrective conditioning to help prevent knee injury and guide return to sport following LE surgery. Table 1: Multivariate linear regression model for pelvic drop, Isometric hip strength and lower extremity kinematics during repeated partial squat activity among female athletes. Variable P Isometric hip abduction strength 0.034* Hip Abduction/Adduction Angle <0.001* Hip Internal/External Rotation Angle 0.936 Ankle Internal/External Rotation Angle 0.072 Height 0.398 Weight 0.011* * Level of significance established at p<0.05

Adaptive Neuro-Fuzzy Determination of the Effect of Experimental Parameters on Vehicle Agent Speed Relative to Vehicle Intruder.

PubMed

Shamshirband, Shahaboddin; Banjanovic-Mehmedovic, Lejla; Bosankic, Ivan; Kasapovic, Suad; Abdul Wahab, Ainuddin Wahid Bin

2016-01-01

Intelligent Transportation Systems rely on understanding, predicting and affecting the interactions between vehicles. The goal of this paper is to choose a small subset from the larger set so that the resulting regression model is simple, yet have good predictive ability for Vehicle agent speed relative to Vehicle intruder. The method of ANFIS (adaptive neuro fuzzy inference system) was applied to the data resulting from these measurements. The ANFIS process for variable selection was implemented in order to detect the predominant variables affecting the prediction of agent speed relative to intruder. This process includes several ways to discover a subset of the total set of recorded parameters, showing good predictive capability. The ANFIS network was used to perform a variable search. Then, it was used to determine how 9 parameters (Intruder Front sensors active (boolean), Intruder Rear sensors active (boolean), Agent Front sensors active (boolean), Agent Rear sensors active (boolean), RSSI signal intensity/strength (integer), Elapsed time (in seconds), Distance between Agent and Intruder (m), Angle of Agent relative to Intruder (angle between vehicles °), Altitude difference between Agent and Intruder (m)) influence prediction of agent speed relative to intruder. The results indicated that distance between Vehicle agent and Vehicle intruder (m) and angle of Vehicle agent relative to Vehicle Intruder (angle between vehicles °) is the most influential parameters to Vehicle agent speed relative to Vehicle intruder.

Propagation-of-uncertainty from contact angle and streaming potential measurements to XDLVO model assessments of membrane-colloid interactions.

PubMed

Muthu, Satish; Childress, Amy; Brant, Jonathan

2014-08-15

Membrane fouling assessed from a fundamental standpoint within the context of the Derjaguin-Landau-Verwey-Overbeek (DLVO) model. The DLVO model requires that the properties of the membrane and foulant(s) be quantified. Membrane surface charge (zeta potential) and free energy values are characterized using streaming potential and contact angle measurements, respectively. Comparing theoretical assessments for membrane-colloid interactions between research groups requires that the variability of the measured inputs be established. The impact that such variability in input values on the outcome from interfacial models must be quantified to determine an acceptable variance in inputs. An interlaboratory study was conducted to quantify the variability in streaming potential and contact angle measurements when using standard protocols. The propagation of uncertainty from these errors was evaluated in terms of their impact on the quantitative and qualitative conclusions on extended DLVO (XDLVO) calculated interaction terms. The error introduced into XDLVO calculated values was of the same magnitude as the calculated free energy values at contact and at any given separation distance. For two independent laboratories to draw similar quantitative conclusions regarding membrane-foulant interfacial interactions the standard error in contact angle values must be⩽2.5°, while that for the zeta potential values must be⩽7 mV. Copyright © 2014 Elsevier Inc. All rights reserved.

Axial and Centrifugal Compressor Mean Line Flow Analysis Method

NASA Technical Reports Server (NTRS)

Veres, Joseph P.

2009-01-01

This paper describes a method to estimate key aerodynamic parameters of single and multistage axial and centrifugal compressors. This mean-line compressor code COMDES provides the capability of sizing single and multistage compressors quickly during the conceptual design process. Based on the compressible fluid flow equations and the Euler equation, the code can estimate rotor inlet and exit blade angles when run in the design mode. The design point rotor efficiency and stator losses are inputs to the code, and are modeled at off design. When run in the off-design analysis mode, it can be used to generate performance maps based on simple models for losses due to rotor incidence and inlet guide vane reset angle. The code can provide an improved understanding of basic aerodynamic parameters such as diffusion factor, loading levels and incidence, when matching multistage compressor blade rows at design and at part-speed operation. Rotor loading levels and relative velocity ratio are correlated to the onset of compressor surge. NASA Stage 37 and the three-stage NASA 74-A axial compressors were analyzed and the results compared to test data. The code has been used to generate the performance map for the NASA 76-B three-stage axial compressor featuring variable geometry. The compressor stages were aerodynamically matched at off-design speeds by adjusting the variable inlet guide vane and variable stator geometry angles to control the rotor diffusion factor and incidence angles.

Ionizing Electrons on the Martian Nightside: Structure and Variability

NASA Astrophysics Data System (ADS)

Lillis, Robert J.; Mitchell, David L.; Steckiewicz, Morgane; Brain, David; Xu, Shaosui; Weber, Tristan; Halekas, Jasper; Connerney, Jack; Espley, Jared; Benna, Mehdi; Elrod, Meredith; Thiemann, Edward; Eparvier, Frank

2018-05-01

The precipitation of suprathermal electrons is the dominant external source of energy deposition and ionization in the Martian nightside upper atmosphere and ionosphere. We investigate the spatial patterns and variability of ionizing electrons from 115 to 600 km altitude on the Martian nightside, using CO2 electron impact ionization frequency (EIIF) as our metric, examining more than 3 years of data collected in situ by the Mars Atmosphere and Volatile EvolutioN spacecraft. We characterize the behavior of EIIF with respect to altitude, solar zenith angle, solar wind pressure, and the geometry and strength of crustal magnetic fields. EIIF has a complex and correlated dependence on these factors, but we find that it generally increases with altitude and solar wind pressure, decreases with crustal magnetic field strength and does not depend detectably on solar zenith angle past 115°. The dependence is governed by (a) energy degradation and backscatter by collisions with atmospheric neutrals below 220 km and (b) magnetic field topology that permits or retards electron access to certain regions. This field topology is dynamic and varies with solar wind conditions, allowing greater electron access at higher altitudes where crustal fields are weaker and also for higher solar wind pressures, which result in stronger draped magnetic fields that push closed crustal magnetic field loops to lower altitudes. This multidimensional electron flux behavior can in the future be parameterized in an empirical model for use as input to global simulations of the nightside upper atmosphere, which currently do not account for this important source of energy.

Rotary acceleration of a subject inhibits choice reaction time to motion in peripheral vision

NASA Technical Reports Server (NTRS)

Borkenhagen, J. M.

1974-01-01

Twelve pilots were tested in a rotation device with visual simulation, alone and in combination with rotary stimulation, in experiments with variable levels of acceleration and variable viewing angles, in a study of the effect of S's rotary acceleration on the choice reaction time for an accelerating target in peripheral vision. The pilots responded to the direction of the visual motion by moving a hand controller to the right or left. Visual-plus-rotary stimulation required a longer choice reaction time, which was inversely related to the level of acceleration and directly proportional to the viewing angle.

The use of variable temperature and magic-angle sample spinning in studies of fulvic acids

USGS Publications Warehouse

Earl, W.L.; Wershaw, R. L.; Thorn, K.A.

1987-01-01

Intensity distortions and poor signal to noise in the cross-polarization magic-angle sample spinning NMR of fulvic acids were investigated and attributed to molecular mobility in these ostensibly "solid" materials. We have shown that inefficiencies in cross polarization can be overcome by lowering the sample temperature to about -60??C. These difficulties can be generalized to many other synthetic and natural products. The use of variable temperature and cross-polarization intensity as a function of contact time can yield valuable qualitative information which can aid in the characterization of many materials. ?? 1987.

Use of the iPhone for Cobb angle measurement in scoliosis.

PubMed

Shaw, Matthew; Adam, Clayton J; Izatt, Maree T; Licina, Paul; Askin, Geoffrey N

2012-06-01

The Cobb technique is the universally accepted method for measuring the severity of spinal deformities. Traditionally, Cobb angles have been measured using protractor and pencil on hardcopy radiographic films. The new generation of mobile 'smartphones' make accurate angle measurement possible using an integrated accelerometer, providing a potentially useful clinical tool for assessing Cobb angles. The purpose of this study was to compare Cobb angle measurements performed using a smartphone and traditional protractor in a series of 20 adolescent idiopathic scoliosis patients. Seven observers measured major Cobb angles on 20 pre-operative postero-anterior radiographs of Adolescent Idiopathic Scoliosis patients with both a standard protractor and using an Apple iPhone. Five of the observers repeated the measurements at least a week after the original measurements. The mean absolute difference between pairs of smartphone/protractor measurements was 2.1°, with a small (1°) bias toward lower Cobb angles with the iPhone. 95% confidence intervals for intra-observer variability were ±3.3° for the protractor and ±3.9° for the iPhone. 95% confidence intervals for inter-observer variability were ±8.3° for the iPhone and ±7.1° for the protractor. Both of these confidence intervals were within the range of previously published Cobb measurement studies. We conclude that the iPhone is an equivalent Cobb measurement tool to the manual protractor, and measurement times are about 15% less. The widespread availability of inclinometer-equipped mobile phones and the ability to store measurements in later versions of the angle measurement software may make these new technologies attractive for clinical measurement applications.

Gender differences in foot shape: a study of Chinese young adults.

PubMed

Hong, Youlian; Wang, Lin; Xu, Dong Qing; Li, Jing Xian

2011-06-01

One important extrinsic factor that causes foot deformity and pain in women is footwear. Women's sports shoes are designed as smaller versions of men's shoes. Based on this, the current study aims to identify foot shape in 1,236 Chinese young adult men and 1,085 Chinese young adult women. Three-dimensional foot shape data were collected through video filming. Nineteen foot shape variables were measured, including girth (4 variables), length (4 variables), width (3 variables), height (7 variables), and angle (1 variable). A comparison of foot measures within the range of the common foot length (FL) categories indicates that women showed significantly smaller values of foot measures in width, height, and girth than men. Three foot types were classified, and distributions of different foot shapes within the same FL were found between women and men. Foot width, medial ball length, ball angle, and instep height showed significant differences among foot types in the same FL for both genders. There were differences in the foot shape between Chinese young women and men, which should be considered in the design of Chinese young adults' sports shoes.

Relationship of moderate and low isometric lumbar extension through architectural and muscular activity variables: a cross sectional study

PubMed Central

2013-01-01

Background No study relating the changes obtained in the architecture of erector spinae (ES) muscle were registered with ultrasound and different intensities of muscle contraction recorded by surface EMG (electromyography) on the ES muscle was found. The aim of this study was analyse the relationship in the response of the ES muscle during isometric moderate and light lumbar isometric extension considering architecture and functional muscle variables. Methods Cross-sectional study. 46 subjects (52% men) with a group mean age of 30.4 (±7.78). The participants developed isometric lumbar extension while performing moderate and low isometric trunk and hip extension in a sitting position with hips flexed 90 degrees and the lumbar spine in neutral position. During these measurements, electromyography recordings and ultrasound images were taken bilaterally. Bilaterally pennation angle, muscle thickness, torque and muscle activation were measured. This study was developed at the human movement analysis laboratory of the Health Science Faculty of the University of Malaga (Spain). Results Strong and moderate correlations were found at moderate and low intensities contraction between the variable of the same intensity, with correlation values ranging from 0.726 (Torque Moderate – EMG Left Moderate) to 0.923 (Angle Left Light – Angle Right Light) (p < 0.001). This correlation is observed between the variables that describe the same intensity of contraction, showing a poor correlation between variables of different intensities. Conclusion There is a strong relationship between architecture and function variables of ES muscle when describe an isometric lumbar extension at light or moderate intensity. PMID:24252273

Comparing wave shoaling methods used in large-scale coastal evolution modeling

NASA Astrophysics Data System (ADS)

Limber, P. W.; Adams, P. N.; Murray, A.

2013-12-01

A variety of methods are available to simulate wave propagation from the deep ocean to the surf zone. They range from simple and computationally fast (e.g. linear wave theory applied to shore-parallel bathymetric contours) to complicated and computationally intense (e.g., Delft's ';Simulating WAves Nearshore', or SWAN, model applied to complex bathymetry). Despite their differences, the goal of each method is the same with respect to coastline evolution modeling: to link offshore waves with rates of (and gradients in) alongshore sediment transport. Choosing a shoaling technique for modeling coastline evolution should be partly informed by the spatial and temporal scales of the model, as well as the model's intent (is it simulating a specific coastline, or exploring generic coastline dynamics?). However, the particular advantages and disadvantages of each technique, and how the advantages/disadvantages vary over different model spatial and temporal scales, are not always clear. We present a wave shoaling model that simultaneously computes breaking wave heights and angles using three increasingly complex wave shoaling routines: the most basic approach assuming shore-parallel bathymetric contours, a wave ray tracing method that includes wave energy convergence and divergence and non-shore-parallel contours, and a spectral wave model (SWAN). Initial results show reasonable agreement between wave models along a flat shoreline for small (1 m) wave heights, low wave angles (0 to 10 degrees), and simple bathymetry. But, as wave heights and angles increase, bathymetry becomes more variable, and the shoreline shape becomes sinuous, the model results begin to diverge. This causes different gradients in alongshore sediment transport between model runs employing different shoaling techniques and, therefore, different coastline behavior. Because SWAN does not approximate wave breaking (which drives alongshore sediment transport) we use a routine to extract grid cells from SWAN output where wave height is approximately one-half of the water depth (a standard wave breaking threshold). The goal of this modeling exercise is to understand under what conditions a simple wave model is sufficient for simulating coastline evolution, and when using a more complex shoaling routine can optimize a coastline model. The Coastline Evolution Model (CEM; Ashton and Murray, 2006) is used to show how different shoaling routines affect modeled coastline behavior. The CEM currently includes the most basic wave shoaling approach to simulate cape and spit formation. We will instead couple it to SWAN, using the insight from the comprehensive wave model (above) to guide its application. This will allow waves transformed over complex bathymetry, such as cape-associated shoals and ridges, to be input for the CEM so that large-scale coastline behavior can be addressed in less idealized environments. Ashton, A., and Murray, A.B., 2006, High-angle wave instability and emergent shoreline shapes: 1. Modeling of sand waves, flying spits, and capes: Journal of Geophysical Research, v. 111, p. F04011, doi:10.1029/2005JF000422.

A Mononuclear Fe(III) Single Molecule Magnet with a 3/2↔5/2 Spin Crossover

PubMed Central

Tran, Ba L.; Adhikari, Debashis; Pink, Maren; Heinemann, Frank W.; Sutter, Jörg; Szilagyi, Robert K.

2012-01-01

The air stable complex [(PNP)FeCl2] (1) (PNP = N[2-P(CHMe2)2-4-methylphenyl]2−), prepared from one-electron oxidation of [(PNP)FeCl] with ClCPh3, displays an unusual S = 3/2 to S = 5/2 transition above 80 K as inferred by the dc SQUID magnetic susceptibility measurement. The ac SQUID magnetization data, at zero field and between frequencies 10 and 1042 Hz, clearly reveals complex 1 to undergo a frequency dependent of the out-of-phase signal and thus be a single molecular magnet with a thermally activated barrier of Ueff = 32-36 cm−1 (47 - 52 K). Variable temperature Mössbauer data also corroborate a significant temperature dependence in δ and ΔEQ values for 1, which is in agreement with the system undergoing a change in spin state. Likewise, variable temperature X-band EPR spectra of 1 reveals the S = 3/2 to be likely the ground state with the S = 5/2 being close in energy. Multi-edge XAS absorption spectra suggest the electronic structure of 1 to be highly covalent with an effective iron oxidation state that is more reduced than the typical ferric complexes due to the significant interaction of the phosphine groups in PNP and Cl ligands with iron. A variable temperature single crystal X-ray diffraction study of 1 collected between 30-300 K also reveals elongation of the Fe–P bond lengths and increment in the Cl–Fe–Cl angle as the S = 5/2 state is populated. Theoretical studies show overall similar orbital pictures except for the d(z2) orbital which is the most sensitivity to change in the geometry and bonding where the quartet (4B) and the sextet (6A) states are close in energy. PMID:22817325

Miniaturized haploscope for testing binocular vision

NASA Technical Reports Server (NTRS)

Decker, T. A.

1973-01-01

Device can reproduce virtually all binocular stimulus conditions (target configuration, vergence angle, and accommodative distance) used to test binocular performance. All subsystems of electronic controls are open-loop and solid-state-controlled and, with the exception of vergence angle drive, utilize dc stepping motors as prime movers. Arrangement is also made for readouts of each variable.

Prediction of Aerodynamic Coefficient using Genetic Algorithm Optimized Neural Network for Sparse Data

NASA Technical Reports Server (NTRS)

Rajkumar, T.; Bardina, Jorge; Clancy, Daniel (Technical Monitor)

2002-01-01

Wind tunnels use scale models to characterize aerodynamic coefficients, Wind tunnel testing can be slow and costly due to high personnel overhead and intensive power utilization. Although manual curve fitting can be done, it is highly efficient to use a neural network to define the complex relationship between variables. Numerical simulation of complex vehicles on the wide range of conditions required for flight simulation requires static and dynamic data. Static data at low Mach numbers and angles of attack may be obtained with simpler Euler codes. Static data of stalled vehicles where zones of flow separation are usually present at higher angles of attack require Navier-Stokes simulations which are costly due to the large processing time required to attain convergence. Preliminary dynamic data may be obtained with simpler methods based on correlations and vortex methods; however, accurate prediction of the dynamic coefficients requires complex and costly numerical simulations. A reliable and fast method of predicting complex aerodynamic coefficients for flight simulation I'S presented using a neural network. The training data for the neural network are derived from numerical simulations and wind-tunnel experiments. The aerodynamic coefficients are modeled as functions of the flow characteristics and the control surfaces of the vehicle. The basic coefficients of lift, drag and pitching moment are expressed as functions of angles of attack and Mach number. The modeled and training aerodynamic coefficients show good agreement. This method shows excellent potential for rapid development of aerodynamic models for flight simulation. Genetic Algorithms (GA) are used to optimize a previously built Artificial Neural Network (ANN) that reliably predicts aerodynamic coefficients. Results indicate that the GA provided an efficient method of optimizing the ANN model to predict aerodynamic coefficients. The reliability of the ANN using the GA includes prediction of aerodynamic coefficients to an accuracy of 110% . In our problem, we would like to get an optimized neural network architecture and minimum data set. This has been accomplished within 500 training cycles of a neural network. After removing training pairs (outliers), the GA has produced much better results. The neural network constructed is a feed forward neural network with a back propagation learning mechanism. The main goal has been to free the network design process from constraints of human biases, and to discover better forms of neural network architectures. The automation of the network architecture search by genetic algorithms seems to have been the best way to achieve this goal.

A LQR-Based Controller with Estimation of Road Bank for Improving Vehicle Lateral and Rollover Stability via Active Suspension

PubMed Central

Sanz, Susana

2017-01-01

In this article, a Linear Quadratic Regulator (LQR) lateral stability and rollover controller has been developed including as the main novelty taking into account the road bank angle and using exclusively active suspension for both lateral stability and rollover control. The main problem regarding the road bank is that it cannot be measured by means of on-board sensors. The solution proposed in this article is performing an estimation of this variable using a Kalman filter. In this way, it is possible to distinguish between the road disturbance component and the vehicle’s roll angle. The controller’s effectiveness has been tested by means of simulations carried out in TruckSim, using an experimentally-validated vehicle model. Lateral load transfer, roll angle, yaw rate and sideslip angle have been analyzed in order to quantify the improvements achieved on the behavior of the vehicle. For that purpose, these variables have been compared with the results obtained from both a vehicle that uses passive suspension and a vehicle using a fuzzy logic controller. PMID:29027910

Determination of bulk diffusion lengths for angle-lapped semiconductor material via the scanning electron microscope: A theoretical analysis

NASA Technical Reports Server (NTRS)

Vonroos, O.

1978-01-01

A standard procedure for the determination of the minority carrier diffusion length by means of a scanning electron microscope (SEM) consists in scanning across an angle-lapped surface of a P-N junction and measuring the resultant short circuit current I sub sc as a function of beam position. A detailed analysis of the I sub sc originating from this configuration is presented. It is found that, for a point source excitation, the I sub sc depends very simply on x, the variable distance between the surface and the junction edge. The expression for the I sub sc of a planar junction device is well known. If d, the constant distance between the plane of the surface of the semiconductor and the junction edge in the expression for the I of a planar junction is merely replaced by x, the variable distance of the corresponding angle-lapped junction, an expression results which is correct to within a small fraction of a percent as long as the angle between the surfaces, 2 theta sub 1, is smaller than 10 deg.

Distribution functions for resonantly trapped orbits in the Galactic disc

NASA Astrophysics Data System (ADS)

Monari, Giacomo; Famaey, Benoit; Fouvry, Jean-Baptiste; Binney, James

2017-11-01

The present-day response of a Galactic disc stellar population to a non-axisymmetric perturbation of the potential has previously been computed through perturbation theory within the phase-space coordinates of the unperturbed axisymmetric system. Such an Eulerian linearized treatment, however, leads to singularities at resonances, which prevent quantitative comparisons with data. Here, we manage to capture the behaviour of the distribution function (DF) at a resonance in a Lagrangian approach, by averaging the Hamiltonian over fast angle variables and re-expressing the DF in terms of a new set of canonical actions and angles variables valid in the resonant region. We then follow the prescription of Binney, assigning to the resonant DF the time average along the orbits of the axisymmetric DF expressed in the new set of actions and angles. This boils down to phase-mixing the DF in terms of the new angles, such that the DF for trapped orbits depends only on the new set of actions. This opens the way to quantitatively fitting the effects of the bar and spirals to Gaia data in terms of DFs in action space.

Dinuclear metallacycles with single M-O(H)-M bridges [M = Fe(II), Co(II), Ni(II), Cu(II)]: effects of large bridging angles on structure and antiferromagnetic superexchange interactions.

PubMed

Reger, Daniel L; Pascui, Andrea E; Foley, Elizabeth A; Smith, Mark D; Jezierska, Julia; Ozarowski, Andrew

2014-02-17

The reactions of M(ClO4)2·xH2O and the ditopic ligands m-bis[bis(1-pyrazolyl)methyl]benzene (Lm) or m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene (Lm*) in the presence of triethylamine lead to the formation of monohydroxide-bridged, dinuclear metallacycles of the formula [M2(μ-OH)(μ-Lm)2](ClO4)3 (M = Fe(II), Co(II), Cu(II)) or [M2(μ-OH)(μ-Lm*)2](ClO4)3 (M = Co(II), Ni(II), Cu(II)). With the exception of the complexes where the ligand is Lm and the metal is copper(II), all of these complexes have distorted trigonal bipyramidal geometry around the metal centers and unusual linear (Lm*) or nearly linear (Lm) M-O-M angles. For the two solvates of [Cu2(μ-OH)(μ-Lm)2](ClO4)3, the Cu-O-Cu angles are significantly bent and the geometry about the metal is distorted square pyramidal. All of the copper(II) complexes have structural distortions expected for the pseudo-Jahn-Teller effect. The two cobalt(II) complexes show moderate antiferromagnetic coupling, -J = 48-56 cm(-1), whereas the copper(II) complexes show very strong antiferromagnetic coupling, -J = 555-808 cm(-1). The largest coupling is observed for [Cu2(μ-OH)(μ-Lm*)2](ClO4)3, the complex with a Cu-O-Cu angle of 180°, such that the exchange interaction is transmitted through the dz(2) and the oxygen s and px orbitals. The interaction decreases, but it is still significant, as the Cu-O-Cu angle decreases and the character of the metal orbital becomes increasingly d(x(2)-y(2)). These intermediate geometries and magnetic interactions lead to spin Hamiltonian parameters for the copper(II) complexes in the EPR spectra that have large E/D ratios and one g matrix component very close to 2. Density functional theory calculations were performed using the hybrid B3LYP functional in association with the TZVPP basis set, resulting in reasonable agreement with the experiments.

Development of a software-hardware complex for studying the process of grinding by a pendulum deformer

NASA Astrophysics Data System (ADS)

Borisov, A. P.

2018-01-01

The article is devoted to the development of a software and hardware complex for investigating the grinding process on a pendulum deformer. The hardware part of this complex is the Raspberry Pi model 2B platform, to which a contactless angle sensor is connected, which allows to obtain data on the angle of deviation of the pendulum surface, usb-cameras, which allow to obtain grain images before and after grinding, and stepping motors allowing lifting of the pendulum surface and adjust the clearance between the pendulum and the supporting surfaces. The program part of the complex is written in C # and allows receiving data from the sensor and usb-cameras, processing the received data, and also controlling the synchronous-step motors in manual and automatic mode. The conducted studies show that the rational mode is the deviation of the pendulum surface by an angle of 400, and the location of the grain in the central zone of the support surface, regardless of the orientation of the grain in space. Also, due to the non-contact angle sensor, energy consumption for grinding, speed and acceleration of the pendulum surface, as well as vitreousness of grain and the energy consumption are calculated. With the help of photographs obtained from usb cameras, the work of a pendulum deformer based on the Rebinder formula and calculation of the grain area before and after grinding is determined.

Refractive Index Imaging of Cells with Variable-Angle Near-Total Internal Reflection (TIR) Microscopy.

PubMed

Bohannon, Kevin P; Holz, Ronald W; Axelrod, Daniel

2017-10-01

The refractive index in the interior of single cells affects the evanescent field depth in quantitative studies using total internal reflection (TIR) fluorescence, but often that index is not well known. We here present method to measure and spatially map the absolute index of refraction in a microscopic sample, by imaging a collimated light beam reflected from the substrate/buffer/cell interference at variable angles of incidence. Above the TIR critical angle (which is a strong function of refractive index), the reflection is 100%, but in the immediate sub-critical angle zone, the reflection intensity is a very strong ascending function of incidence angle. By analyzing the angular position of that edge at each location in the field of view, the local refractive index can be estimated. In addition, by analyzing the steepness of the edge, the distance-to-substrate can be determined. We apply the technique to liquid calibration samples, silica beads, cultured Chinese hamster ovary cells, and primary culture chromaffin cells. The optical technique suffers from decremented lateral resolution, scattering, and interference artifacts. However, it still provides reasonable results for both refractive index (~1.38) and for distance-to-substrate (~150 nm) for the cells, as well as a lateral resolution to about 1 µm.

Analysis of the Sagnac interference imaging spectrometer with a variable optical path difference

NASA Astrophysics Data System (ADS)

Ai, Jingjing; Gao, Peng; Hu, Xiaochen; Zhang, Chunmin; Wang, Xia

2018-03-01

The Sagnac interference imaging spectrometer with a variable optical path difference (OPD) is proposed in this paper, which employs two wedge prisms coupled with a modified Sagnac interferometer, and produces a variable OPD through the moving wedge prism. Compared with the conventional imaging spectrometer, the Sagnac interference imaging spectrometer shows its advantages of miniaturization and insensitive to the non-uniform variation of the moving speed and the environment vibration. The exact expression of the OPD as a function of different parameters is derived, and the influences of the moving displacement, wedge angle and acute angles on the OPD are analyzed and discussed within the scope of engineering design. This study provides an important theoretical and practical guidance for the engineering of the Sagnac interference imaging spectrometer.

Anomalous polymer collapse winding angle distributions

NASA Astrophysics Data System (ADS)

Narros, A.; Owczarek, A. L.; Prellberg, T.

2018-03-01

In two dimensions polymer collapse has been shown to be complex with multiple low temperature states and multi-critical points. Recently, strong numerical evidence has been provided for a long-standing prediction of universal scaling of winding angle distributions, where simulations of interacting self-avoiding walks show that the winding angle distribution for N-step walks is compatible with the theoretical prediction of a Gaussian with a variance growing asymptotically as Clog N . Here we extend this work by considering interacting self-avoiding trails which are believed to be a model representative of some of the more complex behaviour. We provide robust evidence that, while the high temperature swollen state of this model has a winding angle distribution that is also Gaussian, this breaks down at the polymer collapse point and at low temperatures. Moreover, we provide some evidence that the distributions are well modelled by stretched/compressed exponentials, in contradistinction to the behaviour found in interacting self-avoiding walks. Dedicated to Professor Stu Whittington on the occasion of his 75th birthday.

Results of tests CS4 and CS5 to investigate dynamic loads and pressures on 0.03-scale models (Ax1319-3/4 and 45-0) of mated 747 cam and space shuttle orbiter in the Boeing transonic wind tunnel

NASA Technical Reports Server (NTRS)

1976-01-01

A 0.03-scale model of the 747 CAM/Orbiter was tested in an 8 x 12 foot transonic wind tunnel. Dynamic loads, pressure, and empennage flow field data were obtained using pressure transducers, strain gages, and a split film anemometer. The test variables included Mach number, angle of attack, sideslip angle, orbiter tailcone on and off, orbiter partial tailcone, orbiter nozzle air scoops, orbiter body flap angle, and orbiter elevon angle.

The effects of design and operating variables on the response of an axial flow fan to inlet flow distortions. M.S. Thesis

NASA Technical Reports Server (NTRS)

Yocum, A. M., II

1978-01-01

The results of a study of total pressure and velocity circumferential distortions in an axial-flow fan are presented. Some of the fundamental experimental data needed to understand distorted flow phenomena as affected by design and operating variables are provided. The flow through an isolated rotor was examined at various operating conditions with six different distortions and three different blade stagger angles. Circumferential surveys were conducted upstream and downstream of the rotor using five-hole probes in the nonnulling mode. The total pressure and axial velocity distortion data were analyzed to determine the degree of distortion attenuation as a function of blade stagger angle, mean incidence angle, and reduced frequency. The results indicate that, for the rotors tested, the mean incidence or loading has very little effect on the distortion attenuation.

[Measurement and analysis on complex refraction indices of pear pollen in infrared band].

PubMed

Li, Le; Hu, Yi-hua; Gu, You-lin; Chen, Wei; Zhao, Yi-zheng; Chen, Shan-jing

2015-01-01

Pollen is an important part of bioaerosols, and its complex refractive index is a crucial parameter for study on optical characteristics and detection, identification of bioaerosols. The reflection spectra of pear pollen within the 2. 5 - 15µm waveband were measured by squash method. Based on the measured data, the complex refractive index of pear pollen within the wave-band of 2. 5 to 15 µm was calculated by using Kramers-Kroning (K-K) relation, and calculation deviation about incident angle and different reflectivities at high and low frequencies.were analyzed. The results indicate that 18 degrees angle of incidence and different reflectivities at high and low frequencies have little effect on the results, and it is practicable to calculate the complex refractive index of pollen based on its reflection spectral data. The data of complex refractive index of pollen have some reference value for optical characteristics of pollen, detection and identification of bioaerosols.

A low-complexity attitude control method for large-angle agile maneuvers of a spacecraft with control moment gyros

NASA Astrophysics Data System (ADS)

Kawajiri, Shota; Matunaga, Saburo

2017-10-01

This study examines a low-complexity control method that satisfies mechanical constraints by using control moment gyros for an agile maneuver. The method is designed based on the fact that a simple rotation around an Euler's principal axis corresponds to a well-approximated solution of a time-optimal rest-to-rest maneuver. With respect to an agile large-angle maneuver using CMGs, it is suggested that there exists a coasting period in which all gimbal angles are constant, and a constant body angular velocity is almost along the Euler's principal axis. The gimbals are driven such that the coasting period is generated in the proposed method. This allows the problem to be converted into obtaining only a coasting time and gimbal angles such that their combination maximizes body angular velocity along the rotational axis of the maneuver. The effectiveness of the proposed method is demonstrated by using numerical simulations. The results indicate that the proposed method shortens the settling time by 20-70% when compared to that of a traditional feedback method. Additionally, a comparison with an existing path planning method shows that the proposed method achieves a low computational complexity (that is approximately 150 times faster) and a certain level of shortness in the settling time.

Three-gradient regular solution model for simple liquids wetting complex surface topologies

PubMed Central

Akerboom, Sabine; Kamperman, Marleen

2016-01-01

Summary We use regular solution theory and implement a three-gradient model for a liquid/vapour system in contact with a complex surface topology to study the shape of a liquid drop in advancing and receding wetting scenarios. More specifically, we study droplets on an inverse opal: spherical cavities in a hexagonal pattern. In line with experimental data, we find that the surface may switch from hydrophilic (contact angle on a smooth surface θY < 90°) to hydrophobic (effective advancing contact angle θ > 90°). Both the Wenzel wetting state, that is cavities under the liquid are filled, as well as the Cassie–Baxter wetting state, that is air entrapment in the cavities under the liquid, were observed using our approach, without a discontinuity in the water front shape or in the water advancing contact angle θ. Therefore, air entrapment cannot be the main reason why the contact angle θ for an advancing water front varies. Rather, the contact line is pinned and curved due to the surface structures, inducing curvature perpendicular to the plane in which the contact angle θ is observed, and the contact line does not move in a continuous way, but via depinning transitions. The pinning is not limited to kinks in the surface with angles θkink smaller than the angle θY. Even for θkink > θY, contact line pinning is found. Therefore, the full 3D-structure of the inverse opal, rather than a simple parameter such as the wetting state or θkink, determines the final observed contact angle. PMID:27826512

Performance analysis of a CsI-based flat panel detector in a cone beam variable resolution x-ray system

NASA Astrophysics Data System (ADS)

Dahi, Bahram; Keyes, Gary S.; Rendon, David A.; DiBianca, Frank A.

2007-03-01

A new Cone-Beam CT (CBCT) system is introduced that uses the concept of Variable Resolution X-ray (VRX) detection, which has previously been demonstrated to significantly increase spatial resolution for small objects. An amorphous silicon Flat Panel Detector (FPD) with a CsI scintillator (PaxScan 2020, Varian, Salt Lake City, UT) is coupled with a micro-focus x-ray tube (35 - 80 kVp, 10 - 250 μA) to form a CBCT. The FPD is installed on a rotating arm that can be adjusted to any angle θ, called the VRX angle, between 90° and 0° with respect to the x-ray direction. A VRX angle of 90° for the detector corresponds to a conventional CBCT whereas a VRX angle of 30° means that the detector is tilted 90° - 30° = 60° from its perpendicular position. Tilting the FPD in this manner reduces both the line-spread function width and the sampling distance by a factor of sin(θ), thereby increasing detector spatial resolution proportionately. An in-house phantom is used to measure the MTF of the reconstructed CT images using different VRX angles. An increase by a factor of 1.67 +/- 0.007 is observed in the MTF cutoff frequency at 30° compared to 90° in images acquired at 75 kVp. Expected theoretical value for this case is 2.0. The new Cone-Beam Variable Resolution X-ray (CB-VRX) CT system is expected to significantly improve the images acquired from small objects - such as small animals - while exploiting the opportunities offered by a conventional CBCT.

Kinetic measures of restabilisation during volitional stepping reveal age-related alterations in the control of mediolateral dynamic stability.

PubMed

Singer, Jonathan C; McIlroy, William E; Prentice, Stephen D

2014-11-07

Research examining age-related changes in dynamic stability during stepping has recognised the importance of the restabilisation phase, subsequent to foot-contact. While regulation of the net ground reaction force (GRFnet) line of action is believed to influence dynamic stability during steady-state locomotion, such control during restabilisation remains unknown. This work explored the origins of age-related decline in mediolateral dynamic stability by examining the line of action of GRFnet relative to the centre of mass (COM) during restabilisation following voluntary stepping. Healthy younger and older adults (n=20 per group) performed three single-step tasks (varying speed and step placement), altering the challenge to stability control. Age-related differences in magnitude and intertrial variability of the angle of divergence of GRFnet line of action relative to the COM were quantified, along with the peak mediolateral and vertical GRFnet components. The angle of divergence was further examined at discrete points during restabilisation, to uncover events of potential importance to stability control. Older adults exhibited a reduced angle of divergence throughout restabilisation. Temporal and spatial constraints on stepping increased the magnitude and intertrial variability of the angle of divergence, although not differentially among the older adults. Analysis of the time-varying angle of divergence revealed age-related reductions in magnitude, with increases in timing and intertrial timing variability during the later phase of restabilisation. This work further supports the idea that age-related challenges in lateral stability control emerge during restabilisation. Age-related alterations during the later phase of restabilisation may signify challenges with reactive control. Copyright © 2014 Elsevier Ltd. All rights reserved.

A comparison of hematology, plasma chemistry, and injuries in Hickory shad (Alosa mediocris) captured by electrofishing or angling during a spawning run.

PubMed

Matsche, Mark A; Rosemary, Kevin; Stence, Charles P

2017-09-01

Declines in Hickory shad (Alosa mediocris) populations in Chesapeake Bay have prompted efforts at captive propagation of wild broodfish for stock enhancement and research. The objectives of this study were to evaluate injuries sustained, and immediate and delayed (24 hours) effects on blood variables related to 2 fish capturing methods (electrofishing [EF] and angling). Blood specimens were collected from fish immediately following capture by EF and angling (n = 40 per sex and capture method) from the Susquehanna River (MD, USA). Additional fish (n = 25 per sex and capture method) were collected on the same day, placed in holding tanks and bled 24 hours following capture. Blood data that were non-Gaussian in distribution were transformed (Box-Cox), and effects of sex, method of capture, and holding time were tested using ANOVA with general linear models. Fish were evaluated for injuries by necropsy and radiography. Sex-specific differences were observed for RBC, HGB, PCV, MCH, MCHC, total proteins (TP), globulins, glucose, calcium, AST, CK, and lactate, while RBC, HGB, PCV, MCV, MCH, MCHC, TP, albumin, globulins, glucose, potassium, sodium, AST, CK, and lactate differed significantly by fish capturing method. Electrofishing may have induced greater disruption in blood variables, but mortality (4%) was not significantly different compared to angling. Electrofishing for Hickory shad using a constant DC voltage resulted in numerous hematologic and biochemical changes, with no additional injuries or deaths compared to angling. Capture method must be considered when evaluating fish condition, and blood variables should be partitioned by sex during spawning season. © 2017 American Society for Veterinary Clinical Pathology.

A Structural Study of CESA1 Catalytic Domain of Arabidopsis Cellulose Synthesis Complex: Evidence for CESA Trimers.

PubMed

Vandavasi, Venu Gopal; Putnam, Daniel K; Zhang, Qiu; Petridis, Loukas; Heller, William T; Nixon, B Tracy; Haigler, Candace H; Kalluri, Udaya; Coates, Leighton; Langan, Paul; Smith, Jeremy C; Meiler, Jens; O'Neill, Hugh

2016-01-01

A cellulose synthesis complex with a "rosette" shape is responsible for synthesis of cellulose chains and their assembly into microfibrils within the cell walls of land plants and their charophyte algal progenitors. The number of cellulose synthase proteins in this large multisubunit transmembrane protein complex and the number of cellulose chains in a microfibril have been debated for many years. This work reports a low resolution structure of the catalytic domain of CESA1 from Arabidopsis (Arabidopsis thaliana; AtCESA1CatD) determined by small-angle scattering techniques and provides the first experimental evidence for the self-assembly of CESA into a stable trimer in solution. The catalytic domain was overexpressed in Escherichia coli, and using a two-step procedure, it was possible to isolate monomeric and trimeric forms of AtCESA1CatD. The conformation of monomeric and trimeric AtCESA1CatD proteins were studied using small-angle neutron scattering and small-angle x-ray scattering. A series of AtCESA1CatD trimer computational models were compared with the small-angle x-ray scattering trimer profile to explore the possible arrangement of the monomers in the trimers. Several candidate trimers were identified with monomers oriented such that the newly synthesized cellulose chains project toward the cell membrane. In these models, the class-specific region is found at the periphery of the complex, and the plant-conserved region forms the base of the trimer. This study strongly supports the "hexamer of trimers" model for the rosette cellulose synthesis complex that synthesizes an 18-chain cellulose microfibril as its fundamental product. © 2016 American Society of Plant Biologists. All Rights Reserved.

A Structural Study of CESA1 Catalytic Domain of Arabidopsis Cellulose Synthesis Complex: Evidence for CESA Trimers1

PubMed Central

Zhang, Qiu; Petridis, Loukas; Nixon, B. Tracy; Haigler, Candace H.; Kalluri, Udaya; Coates, Leighton; Smith, Jeremy C.; Meiler, Jens

2016-01-01

A cellulose synthesis complex with a “rosette” shape is responsible for synthesis of cellulose chains and their assembly into microfibrils within the cell walls of land plants and their charophyte algal progenitors. The number of cellulose synthase proteins in this large multisubunit transmembrane protein complex and the number of cellulose chains in a microfibril have been debated for many years. This work reports a low resolution structure of the catalytic domain of CESA1 from Arabidopsis (Arabidopsis thaliana; AtCESA1CatD) determined by small-angle scattering techniques and provides the first experimental evidence for the self-assembly of CESA into a stable trimer in solution. The catalytic domain was overexpressed in Escherichia coli, and using a two-step procedure, it was possible to isolate monomeric and trimeric forms of AtCESA1CatD. The conformation of monomeric and trimeric AtCESA1CatD proteins were studied using small-angle neutron scattering and small-angle x-ray scattering. A series of AtCESA1CatD trimer computational models were compared with the small-angle x-ray scattering trimer profile to explore the possible arrangement of the monomers in the trimers. Several candidate trimers were identified with monomers oriented such that the newly synthesized cellulose chains project toward the cell membrane. In these models, the class-specific region is found at the periphery of the complex, and the plant-conserved region forms the base of the trimer. This study strongly supports the “hexamer of trimers” model for the rosette cellulose synthesis complex that synthesizes an 18-chain cellulose microfibril as its fundamental product. PMID:26556795

A Structural Study of CESA1 Catalytic Domain of Arabidopsis Cellulose Synthesis Complex: Evidence for CESA Trimers

DOE PAGES

Vandavasi, Venu Gopal; Putnam, Daniel K.; Zhang, Qiu; ...

2015-11-10

In a cellulose synthesis complex a "rosette" shape is responsible for the synthesis of cellulose chains and their assembly into microfibrils within the cell walls of land plants and their charophyte algal progenitors. The number of cellulose synthase proteins in this large multisubunit transmembrane protein complex and the number of cellulose chains in a microfibril have been debated for many years. Our work reports a low resolution structure of the catalytic domain of CESA1 from Arabidopsis (Arabidopsis thaliana; AtCESA1CatD) determined by small-angle scattering techniques and provides the first experimental evidence for the self-assembly of CESA into a stable trimer inmore » solution. The catalytic domain was overexpressed in Escherichia coli, and using a two-step procedure, it was possible to isolate monomeric and trimeric forms of AtCESA1CatD. Moreover, the conformation of monomeric and trimeric AtCESA1CatD proteins were studied using small-angle neutron scattering and small-angle x-ray scattering. A series of AtCESA1CatD trimer computational models were compared with the small-angle x-ray scattering trimer profile to explore the possible arrangement of the monomers in the trimers. Several candidate trimers were identified with monomers oriented such that the newly synthesized cellulose chains project toward the cell membrane. In these models, the class-specific region is found at the periphery of the complex, and the plant-conserved region forms the base of the trimer. Finally, this study strongly supports the "hexamer of trimers" model for the rosette cellulose synthesis complex that synthesizes an 18-chain cellulose microfibril as its fundamental product.« less

Diffraction scattering computed tomography: a window into the structures of complex nanomaterials

PubMed Central

Birkbak, M. E.; Leemreize, H.; Frølich, S.; Stock, S. R.

2015-01-01

Modern functional nanomaterials and devices are increasingly composed of multiple phases arranged in three dimensions over several length scales. Therefore there is a pressing demand for improved methods for structural characterization of such complex materials. An excellent emerging technique that addresses this problem is diffraction/scattering computed tomography (DSCT). DSCT combines the merits of diffraction and/or small angle scattering with computed tomography to allow imaging the interior of materials based on the diffraction or small angle scattering signals. This allows, e.g., one to distinguish the distributions of polymorphs in complex mixtures. Here we review this technique and give examples of how it can shed light on modern nanoscale materials. PMID:26505175

Initial Polarimetric Analysis of the Vestoid Asteroid Family

NASA Astrophysics Data System (ADS)

Maleszewski, C.; McMillan, R. S.; Smith, P.

2013-12-01

Observations of polarized light scattered off of asteroid regolith have been used to compare the major asteroid taxonomic types. Members within a taxonomic type tend to have similar polarimetric phase curves (linear polarization vs. phase angle). The polarization also exhibits a wavelength dependence. For the S-complex, the polarization decreases linearly with increasing wavelength. This is different from the C-complex, which has the opposite dependence of polarization on wavelength. The slope of wavelength dependence also changes with phase angle for both complexes; at higher phase angles, the wavelength dependence is steeper. One of the less analyzed taxonomic types with regards to polarization is the V-type. Focus has been placed on the largest member of the V-types: Vesta. However, the Vestoids, which are thought to be collisional remnants of Vesta, have not been analyzed. Due to Vesta's differentiation, the Vestoids as a whole should contain members with significant differences in composition. This in turn should mean significant variations in the polarization observed from these bodies. In order to confirm such differences, we have begun a polarimetric survey of Vestoids. Over thirty observations of six different Vestoids were obtained using the SPOL spectropolarimeter (http://james.as.arizona.edu/~psmith/SPOL/ ) and Steward Observatory telescopes. The wavelength dependence of linear polarization was plotted with respect to the observed phase angle. The linear polarization trends in each of the synthesized B, V, and R bandpasses do not fit a single curve, contrary to that displayed by ensembles of asteroids in other taxonomic complexes. This suggests that these particular targets have dissimilar albedos. This is consistent with the range of albedos measured for the Vestoids through thermal models. However, there is no discernable trend for individual Vestoids with regards to wavelength dependence. Unlike the S- and C-complexes, our data show examples in which the polarization both increases and decreases with wavelength. When our Vestoid data are combined, the wavelength dependence becomes more negative (i.e. polarization tends to decrease with wavelength) as phase angle increases. This is similar to the trend observed in the S-complex, but the opposite trend when compared to the C-complex. The wavelength dependence of Vestoids suggests that this dependence is not strongly affected by albedo. The Vestoids are significantly smaller in size than the asteroids for which other measurements of the wavelength dependence have been analyzed. Possible grain size effects could be a cause of the dissimilar wavelength dependence between the Vestoids and other taxonomic complexes. However, further investigation is needed to explore this possibility.

Human NF-κB1 Haploinsufficiency and Epstein-Barr Virus-Induced Disease-Molecular Mechanisms and Consequences.

PubMed

Hoeger, Birgit; Serwas, Nina Kathrin; Boztug, Kaan

2017-01-01

Nuclear factor kappa-light-chain-enhancer of activated B cells 1 (NF-κB1)-related human primary immune deficiencies have initially been characterized as defining a subgroup of common variable immunodeficiencies (CVIDs), representing intrinsic B-cell disorders with antibody deficiency and recurrent infections of various kind. Recent evidence indicates that NF-κB1 haploinsufficiency underlies a variable type of combined immunodeficiency (CID) affecting both B and T lymphocyte compartments, with a broadened spectrum of disease manifestations, including Epstein-Barr virus (EBV)-induced lymphoproliferative disease and immediate life-threatening consequences. As part of this review series focused on EBV-related primary immunodeficiencies, we discuss the current clinical and molecular understanding of monoallelic NFKB1 germline mutations with special focus on the emerging context of EBV-associated disease. We outline mechanistic implications of dysfunctional NF-κB1 in B and T cells and discuss the fatal relation of impaired T-cell function with the inability to clear EBV infections. Finally, we compare common and suggested treatment angles in the context of this complex disease.

Human NF-κB1 Haploinsufficiency and Epstein–Barr Virus-Induced Disease—Molecular Mechanisms and Consequences

PubMed Central

Hoeger, Birgit; Serwas, Nina Kathrin; Boztug, Kaan

2018-01-01

Nuclear factor kappa-light-chain-enhancer of activated B cells 1 (NF-κB1)-related human primary immune deficiencies have initially been characterized as defining a subgroup of common variable immunodeficiencies (CVIDs), representing intrinsic B-cell disorders with antibody deficiency and recurrent infections of various kind. Recent evidence indicates that NF-κB1 haploinsufficiency underlies a variable type of combined immunodeficiency (CID) affecting both B and T lymphocyte compartments, with a broadened spectrum of disease manifestations, including Epstein–Barr virus (EBV)-induced lymphoproliferative disease and immediate life-threatening consequences. As part of this review series focused on EBV-related primary immunodeficiencies, we discuss the current clinical and molecular understanding of monoallelic NFKB1 germline mutations with special focus on the emerging context of EBV-associated disease. We outline mechanistic implications of dysfunctional NF-κB1 in B and T cells and discuss the fatal relation of impaired T-cell function with the inability to clear EBV infections. Finally, we compare common and suggested treatment angles in the context of this complex disease. PMID:29403474

[Anatomy of fractures of the inferior scapular angle].

PubMed

Bartoníček, J; Tuček, M; Malík, J

2018-01-01

The aim of this study is to describe the anatomy of fractures of the inferior angle and the adjacent part of the scapular body, based on 3D CT reconstructions. In a series of 375 scapular fractures, we identified a total of 20 fractures of the inferior angle of the scapular body (13 men, 7 women), with a mean patient age of 50 years (range 3373). In all fractures, 3D CT reconstructions were obtained, allowing an objective evaluation of the fracture pattern with a focus on the size and shape of the inferior angle fragment, propagation of the fracture line to the lateral and medial borders of the infraspinous part of the scapular body, fragment displacement and any additional fracture of the ipsilateral scapula and the shoulder girdle. We identified a total of 5 types of fracture involving the distal half of the infraspinous part of the scapular body. The first type, recorded in 5 cases, affected only the apex of the inferior angle, with a small part of the adjacent medial border. The second type, occurring in 4 cases, involved fractures separating the entire inferior angle. The third type, represented by 4 cases, was characterized by a fracture line starting medially close above the inferior angle and passing proximolaterally. The separated fragment had a shape of a big drop, carrying also the distal half of the lateral pillar in addition to the inferior angle. In the fourth type identified in 5 fractures, the separated fragment was formed both by the inferior angle and a variable part of the medial border. The fifth type, being by its nature a transition to the fracture of the infraspinous part of the body, was recorded in 2 cases, with the same V-shaped fragment. Fractures of the inferior angle and the adjacent part of the scapular body are groups of fractures differing from other infraspinous fractures of the scapular body. Although these fractures are highly variable in terms of shape, they have the same course of fracture line and the manner of displacement.Key words: scapula scapula fractures scapular body fractures inferior angle classification of scapular body fractures.

Biometric parameters in different stages of primary angle closure using low-coherence interferometry.

PubMed

Yazdani, Shahin; Akbarian, Shadi; Pakravan, Mohammad; Doozandeh, Azadeh; Afrouzifar, Mohsen

2015-03-01

To compare ocular biometric parameters using low-coherence interferometry among siblings affected with different degrees of primary angle closure (PAC). In this cross-sectional comparative study, a total of 170 eyes of 86 siblings from 47 families underwent low-coherence interferometry (LenStar 900; Haag-Streit, Koeniz, Switzerland) to determine central corneal thickness, anterior chamber depth (ACD), aqueous depth (AD), lens thickness (LT), vitreous depth, and axial length (AL). Regression coefficients were applied to show the trend of the measured variables in different stages of angle closure. To evaluate the discriminative power of the parameters, receiver operating characteristic curves were used. Best cutoff points were selected based on the Youden index. Sensitivity, specificity, positive and negative predicative values, positive and negative likelihood ratios, and diagnostic accuracy were determined for each variable. All biometric parameters changed significantly from normal eyes to PAC suspects, PAC, and PAC glaucoma; there was a significant stepwise decrease in central corneal thickness, ACD, AD, vitreous depth, and AL, and an increase in LT and LT/AL. Anterior chamber depth and AD had the best diagnostic power for detecting angle closure; best levels of sensitivity and specificity were obtained with cutoff values of 3.11 mm for ACD and 2.57 mm for AD. Biometric parameters measured by low-coherence interferometry demonstrated a significant and stepwise change among eyes affected with various degrees of angle closure. Although the current classification scheme for angle closure is based on anatomical features, it has excellent correlation with biometric parameters.

Results of a simulator test comparing two display concepts for piloted flight-path-angle control

NASA Technical Reports Server (NTRS)

Kelley, W. W.

1978-01-01

Results of a simulator experiment which was conducted in order to compare pilot gamma-control performance using two display formats are reported. Pilots flew a variable flight path angle tracking task in the landing configuration. Pilot and airplane performance parameters were recorded and pilot comments noted for each case.

Multiple Scattering Effects on Pulse Propagation in Optically Turbid Media.

NASA Astrophysics Data System (ADS)

Joelson, Bradley David

The effects of multiple scattering in a optically turbid media is examined for an impulse solution to the radiative transfer equation for a variety of geometries and phase functions. In regions where the complexities of the phase function proved too cumbersome for analytic methods Monte Carlo techniques were developed to describe the entire scalar radiance distribution. The determination of a general spread function is strongly dependent on geometry and particular regions where limits can be placed on the variables of the problem. Hence, the general spread function is first simplified by considering optical regions which reduce the complexity of the variable dependence. First, in the small-angle limit we calculate some contracted spread functions along with their moments and then use Monte Carlo techniques to establish the limitations imposed by the small-angle approximation in planar geometry. The point spread function (PSF) for a spherical geometry is calculated for the full angular spread in the forward direction of ocean waters using Monte Carlo methods in the optically thin and moderate depths and analytic methods in the diffusion domain. The angular dependence of the PSF for various ocean waters is examined for a range of optical parameters. The analytic method used in the diffusion calculation is justified by examining the angular dependence of the radiance of a impulse solution in a planar geometry for a prolongated Henyey-Greenstein phase function of asymmetry factor approximately equal to that of the ocean phase functions. The Legendre moments of the radiance are examined in order to examine the viability of the diffusion approximation which assumes a linearly anisotropic angular distribution for the radiance. A realistic lidar calculation is performed for a variety of ocean waters to determine the effects of multiple scattering on the determination of the speed of sound by using the range gated frequency spectrum of the lidar signal. It is shown that the optical properties of the ocean help to ensure single scatter form for the frequency spectra of the lidar signal. This spectra can then be used to compute the speed of sound and backscatter probability.

Metronome Cueing of Walking Reduces Gait Variability after a Cerebellar Stroke.

PubMed

Wright, Rachel L; Bevins, Joseph W; Pratt, David; Sackley, Catherine M; Wing, Alan M

2016-01-01

Cerebellar stroke typically results in increased variability during walking. Previous research has suggested that auditory cueing reduces excessive variability in conditions such as Parkinson's disease and post-stroke hemiparesis. The aim of this case report was to investigate whether the use of a metronome cue during walking could reduce excessive variability in gait parameters after a cerebellar stroke. An elderly female with a history of cerebellar stroke and recurrent falling undertook three standard gait trials and three gait trials with an auditory metronome. A Vicon system was used to collect 3-D marker trajectory data. The coefficient of variation was calculated for temporal and spatial gait parameters. SDs of the joint angles were calculated and used to give a measure of joint kinematic variability. Step time, stance time, and double support time variability were reduced with metronome cueing. Variability in the sagittal hip, knee, and ankle angles were reduced to normal values when walking to the metronome. In summary, metronome cueing resulted in a decrease in variability for step, stance, and double support times and joint kinematics. Further research is needed to establish whether a metronome may be useful in gait rehabilitation after cerebellar stroke and whether this leads to a decreased risk of falling.

Metronome Cueing of Walking Reduces Gait Variability after a Cerebellar Stroke

PubMed Central

Wright, Rachel L.; Bevins, Joseph W.; Pratt, David; Sackley, Catherine M.; Wing, Alan M.

2016-01-01

Cerebellar stroke typically results in increased variability during walking. Previous research has suggested that auditory cueing reduces excessive variability in conditions such as Parkinson’s disease and post-stroke hemiparesis. The aim of this case report was to investigate whether the use of a metronome cue during walking could reduce excessive variability in gait parameters after a cerebellar stroke. An elderly female with a history of cerebellar stroke and recurrent falling undertook three standard gait trials and three gait trials with an auditory metronome. A Vicon system was used to collect 3-D marker trajectory data. The coefficient of variation was calculated for temporal and spatial gait parameters. SDs of the joint angles were calculated and used to give a measure of joint kinematic variability. Step time, stance time, and double support time variability were reduced with metronome cueing. Variability in the sagittal hip, knee, and ankle angles were reduced to normal values when walking to the metronome. In summary, metronome cueing resulted in a decrease in variability for step, stance, and double support times and joint kinematics. Further research is needed to establish whether a metronome may be useful in gait rehabilitation after cerebellar stroke and whether this leads to a decreased risk of falling. PMID:27313563

Digital Breast Tomosynthesis: Observer Performance of Clustered Microcalcification Detection on Breast Phantom Images Acquired with an Experimental System Using Variable Scan Angles, Angular Increments, and Number of Projection Views

PubMed Central

Goodsitt, Mitchell M.; Helvie, Mark A.; Zelakiewicz, Scott; Schmitz, Andrea; Noroozian, Mitra; Paramagul, Chintana; Roubidoux, Marilyn A.; Nees, Alexis V.; Neal, Colleen H.; Carson, Paul; Lu, Yao; Hadjiiski, Lubomir; Wei, Jun

2014-01-01

Purpose To investigate the dependence of microcalcification cluster detectability on tomographic scan angle, angular increment, and number of projection views acquired at digital breast tomosynthesis (DBTdigital breast tomosynthesis). Materials and Methods A prototype DBTdigital breast tomosynthesis system operated in step-and-shoot mode was used to image breast phantoms. Four 5-cm-thick phantoms embedded with 81 simulated microcalcification clusters of three speck sizes (subtle, medium, and obvious) were imaged by using a rhodium target and rhodium filter with 29 kV, 50 mAs, and seven acquisition protocols. Fixed angular increments were used in four protocols (denoted as scan angle, angular increment, and number of projection views, respectively: 16°, 1°, and 17; 24°, 3°, and nine; 30°, 3°, and 11; and 60°, 3°, and 21), and variable increments were used in three (40°, variable, and 13; 40°, variable, and 15; and 60°, variable, and 21). The reconstructed DBTdigital breast tomosynthesis images were interpreted by six radiologists who located the microcalcification clusters and rated their conspicuity. Results The mean sensitivity for detection of subtle clusters ranged from 80% (22.5 of 28) to 96% (26.8 of 28) for the seven DBTdigital breast tomosynthesis protocols; the highest sensitivity was achieved with the 16°, 1°, and 17 protocol (96%), but the difference was significant only for the 60°, 3°, and 21 protocol (80%, P < .002) and did not reach significance for the other five protocols (P = .01–.15). The mean sensitivity for detection of medium and obvious clusters ranged from 97% (28.2 of 29) to 100% (24 of 24), but the differences fell short of significance (P = .08 to >.99). The conspicuity of subtle and medium clusters with the 16°, 1°, and 17 protocol was rated higher than those with other protocols; the differences were significant for subtle clusters with the 24°, 3°, and nine protocol and for medium clusters with 24°, 3°, and nine; 30°, 3°, and 11; 60°, 3° and 21; and 60°, variable, and 21 protocols (P < .002). Conclusion With imaging that did not include x-ray source motion or patient motion during acquisition of the projection views, narrow-angle DBTdigital breast tomosynthesis provided higher sensitivity and conspicuity than wide-angle DBTdigital breast tomosynthesis for subtle microcalcification clusters. © RSNA, 2014 PMID:25007048

10. View northwest Typical panel detail (south chord) of variable ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

10. View northwest Typical panel detail (south chord) of variable section girder showing riveted connections, angle stiffeners for girder web, and nuts securing wind bracing rods. - Walpole-Westminster Bridge, Spanning Connecticut River between Walpole, NH & Westminster, VT, Walpole, Cheshire County, NH

Elbow kinematics during sit-to-stand and stand-to-sit movements.

PubMed

Packer, T L; Wyss, U P; Costigan, P A

1993-11-01

The sit-to-stand and stand-to-sit movements of 10 healthy women (mean age 52.4 years) were subjected to a descriptive analysis that yielded a definition of phases, determination of the peak angles reached, maximum angular velocity during each movement, and the sequencing of key events. While subjects showed little intrasubject variability, intersubject variability was evident. Subjects differed in the joint angles and angular velocity recorded, but the sequence of flexion/extension and rotation events were unchanged. Changes in direction of flexion/extension and rotation tended to occur very close in time, if not at the same time. Copyright © 1993. Published by Elsevier Ltd.

The SIR-B science investigations plan: Introduction

NASA Technical Reports Server (NTRS)

1984-01-01

The Shuttle Imaging Radar-B (SIR-B) and its capabilities are described. The SIR-B instrument is an upgraded version of SIR-A that has the additional capability of tilting the antenna mechanically to acquire data at incidence angles that vary from 15 to 60 deg. Like SEASAT and SIR-A, SIR-B will be an L-band (23-cm) HH polarized radar. The variable-incidence-angle capability will allow several experiments. A specific area may be imaged with a variety of incidence angles on successive days. These images can then be registered and used to produce curves of backscatter as a function of incidence angle for various terrain types. These curves can be used ultimately to characterize the terrain. Stereoimaging may also be done in the multiple-incidence-angle mode. In addition, large areas may be imaged and mosaicked together with only slight variations in incidence angle with each swath.

Numerical Investigations of Slip Phenomena in Centrifugal Compressor Impellers

NASA Astrophysics Data System (ADS)

Huang, Jeng-Min; Luo, Kai-Wei; Chen, Ching-Fu; Chiang, Chung-Ping; Wu, Teng-Yuan; Chen, Chun-Han

2013-03-01

This study systematically investigates the slip phenomena in the centrifugal air compressor impellers by CFD. Eight impeller blades for different specific speeds, wrap angles and exit blade angles are designed by compressor design software to analyze their flow fields. Except for the above three variables, flow rate and number of blades are the other two. Results show that the deviation angle decreases as the flow rate increases. The specific speed is not an important parameter regarding deviation angle or slip factor for general centrifugal compressor impellers. The slip onset position is closely related to the position of the peak value in the blade loading factor distribution. When no recirculation flow is present at the shroud, the variations of slip factor under various flow rates are mainly determined by difference between maximum blade angle and exit blade angle, Δβmax-2. The solidity should be of little importance to slip factor correlations in centrifugal compressor impellers.

Controlling the angle range in acoustic low-frequency forbidden transmission in solid-fluid superlattice

NASA Astrophysics Data System (ADS)

Zhang, Sai; Xu, Bai-qiang; Cao, Wenwu

2018-03-01

We have investigated low-frequency forbidden transmission (LFT) of acoustic waves with frequency lower than the first Bragg bandgap in a solid-fluid superlattice (SFSL). LFT is formed when the acoustic planar wave impinges on the interface of a SFSL within a certain angle range. However, for the SFSL comprised of metallic material and water, the angle range of LFT is extremely narrow, which restricts its practical applications. The variation characteristics of the angle range have been comprehensively studied here by the control variable method. The results suggest that the filling ratio, layer number, wave velocity, and mass density of the constituent materials have a significant impact on the angle range. Based on our results, an effective strategy for obtaining LFT with a broad angle range is provided, which will be useful for potential applications of LFT in various devices, such as low frequency filters and subwavelength one-way diodes.

Implementation and flight tests for the Digital Integrated Automatic Landing System (DIALS). Part 2: Complete set of flight data

NASA Technical Reports Server (NTRS)

Hueschen, R. M.

1986-01-01

Five flight tests of the Digital Automated Landing System (DIALS) were conducted on the Advanced Transport Operating System (ATOPS) Transportation Research Vehicle (TSRV)--a modified Boeing 737 Aircraft for advanced controls and displays research. These flight tests were conducted at NASA's Wallops Flight Center using the Microwave Landing System (MLS) installation on Runway 22. This report is primarily a collection of data plots of all performance variables recorded for the entire five flight tests. A description and source of the performance variables is included. Performance variables include inertial data, air data, automatic control commands, control servo positions, sensor data, DIALS guidance and control parameters, and Kalman filter data. This data illustrates low overshoot captures of the localizer for intercept angles of 20 deg, 30 deg, 40 deg, and 50 deg intercept angles, and low overshoot captures of the glideslope slope for 3 deg, 4.5 deg, and 5 deg glideslopes. Flare maneuvers were successfully performed from the various glideslope angles and good decrab maneuvers were performed in crosswinds of 6 knots. In 18 to 20 knot crosswind conditions rudder limiting occurred which caused lateral drifting although heading alignment was achieved.

Development of variable-magnification X-ray Bragg optics.

PubMed

Hirano, Keiichi; Yamashita, Yoshiki; Takahashi, Yumiko; Sugiyama, Hiroshi

2015-07-01

A novel X-ray Bragg optics is proposed for variable-magnification of an X-ray beam. This X-ray Bragg optics is composed of two magnifiers in a crossed arrangement, and the magnification factor, M, is controlled through the azimuth angle of each magnifier. The basic properties of the X-ray optics such as the magnification factor, image transformation matrix and intrinsic acceptance angle are described based on the dynamical theory of X-ray diffraction. The feasibility of the variable-magnification X-ray Bragg optics was verified at the vertical-wiggler beamline BL-14B of the Photon Factory. For X-ray Bragg magnifiers, Si(220) crystals with an asymmetric angle of 14° were used. The magnification factor was calculated to be tunable between 0.1 and 10.0 at a wavelength of 0.112 nm. At various magnification factors (M ≥ 1.0), X-ray images of a nylon mesh were observed with an air-cooled X-ray CCD camera. Image deformation caused by the optics could be corrected by using a 2 × 2 transformation matrix and bilinear interpolation method. Not only absorption-contrast but also edge-contrast due to Fresnel diffraction was observed in the magnified images.

Levee reliability analyses for various flood return periods - a case study in Southern Taiwan

NASA Astrophysics Data System (ADS)

Huang, W.-C.; Yu, H.-W.; Weng, M.-C.

2015-01-01

In recent years, heavy rainfall conditions have caused damages around the world. To prevent damages by floods, levees have often been constructed in prone-to-inundation areas. This study performed reliability analyses for the Chiuliao 1st Levee located in southern Taiwan. The failure-related parameters were the water level, the scouring depth, and the in-situ friction angle. Three major failure mechanisms were considered, including the slope sliding failure of the levee, and the sliding and overturning failures of the retaining wall. When the variabilities of the in-situ friction angle and the scouring depth are considered for various flood return periods, the variations of the factor of safety (FS) for the different failure mechanisms show that the retaining wall sliding and overturning failures are more sensitive to the variability of the friction angle. When the flood return period is greater than 2 years, the levee can undergo slope sliding failure for all values of the water level difference. The results for levee stability analysis considering the variability of different parameters could assist engineers in designing the levee cross sections, especially with potential failure mechanisms in mind.

Roles of nonlocal conductivity on spin Hall angle measurement

NASA Astrophysics Data System (ADS)

Chen, Kai; Zhang, Shufeng

2017-10-01

Spin Hall angle characterizes the rate of spin-charge current conversion and it has become one of the most important material parameters for spintronics physics and device application. A long-standing controversy is that the spin Hall angles for a given material measured by spin pumping and by spin Hall torque experiments are inconsistent and they could differ by as much as an order of magnitude. By using the linear response spin transport theory, we explicitly formulate the relation between the spin Hall angle and measured variables in different experiments. We find that the nonlocal conductivity inherited in the layered structure plays a key role to resolve conflicting values of the spin Hall angle. We provide a generalized scheme for extracting spin transport coefficients from experimental data.

An observational method for fast stochastic X-ray polarimetry timing

NASA Astrophysics Data System (ADS)

Ingram, Adam R.; Maccarone, Thomas J.

2017-11-01

The upcoming launch of the first space based X-ray polarimeter in ˜40 yr will provide powerful new diagnostic information to study accreting compact objects. In particular, analysis of rapid variability of the polarization degree and angle will provide the opportunity to probe the relativistic motions of material in the strong gravitational fields close to the compact objects, and enable new methods to measure black hole and neutron star parameters. However, polarization properties are measured in a statistical sense, and a statistically significant polarization detection requires a fairly long exposure, even for the brightest objects. Therefore, the sub-minute time-scales of interest are not accessible using a direct time-resolved analysis of polarization degree and angle. Phase-folding can be used for coherent pulsations, but not for stochastic variability such as quasi-periodic oscillations. Here, we introduce a Fourier method that enables statistically robust detection of stochastic polarization variability for arbitrarily short variability time-scales. Our method is analogous to commonly used spectral-timing techniques. We find that it should be possible in the near future to detect the quasi-periodic swings in polarization angle predicted by Lense-Thirring precession of the inner accretion flow. This is contingent on the mean polarization degree of the source being greater than ˜4-5 per cent, which is consistent with the best current constraints on Cygnus X-1 from the late 1970s.

Enabling Advanced Wind-Tunnel Research Methods Using the NASA Langley 12-Foot Low Speed Tunnel

NASA Technical Reports Server (NTRS)

Busan, Ronald C.; Rothhaar, Paul M.; Croom, Mark A.; Murphy, Patrick C.; Grafton, Sue B.; O-Neal, Anthony W.

2014-01-01

Design of Experiment (DOE) testing methods were used to gather wind tunnel data characterizing the aerodynamic and propulsion forces and moments acting on a complex vehicle configuration with 10 motor-driven propellers, 9 control surfaces, a tilt wing, and a tilt tail. This paper describes the potential benefits and practical implications of using DOE methods for wind tunnel testing - with an emphasis on describing how it can affect model hardware, facility hardware, and software for control and data acquisition. With up to 23 independent variables (19 model and 2 tunnel) for some vehicle configurations, this recent test also provides an excellent example of using DOE methods to assess critical coupling effects in a reasonable timeframe for complex vehicle configurations. Results for an exploratory test using conventional angle of attack sweeps to assess aerodynamic hysteresis is summarized, and DOE results are presented for an exploratory test used to set the data sampling time for the overall test. DOE results are also shown for one production test characterizing normal force in the Cruise mode for the vehicle.

Crystallization using reverse micelles and water-in-oil microemulsion systems: the highly selective tool for the purification of organic compounds from complex mixtures.

PubMed

Kljajic, Alen; Bester-Rogac, Marija; Klobcar, Andrej; Zupet, Rok; Pejovnik, Stane

2013-02-01

The active pharmaceutical ingredient orlistat is usually manufactured using a semi-synthetic procedure, producing crude product and complex mixtures of highly related impurities with minimal side-chain structure variability. It is therefore crucial for the overall success of industrial/pharmaceutical application to develop an effective purification process. In this communication, we present the newly developed water-in-oil reversed micelles and microemulsion system-based crystallization process. Physiochemical properties of the presented crystallization media were varied through surfactants and water composition, and the impact on efficiency was measured through final variation of these two parameters. Using precisely defined properties of the dispersed water phase in crystallization media, a highly efficient separation process in terms of selectivity and yield was developed. Small-angle X-ray scattering, high-performance liquid chromatography, mass spectrometry, and scanning electron microscopy were used to monitor and analyze the separation processes and orlistat products obtained. Typical process characteristics, especially selectivity and yield in regard to reference examples, were compared and discussed. Copyright © 2012 Wiley Periodicals, Inc.

Advanced Electrocardiographic Predictors of Sudden Death in Familial Dysautonomia

NASA Technical Reports Server (NTRS)

Solaimanzadeh, I.; Schlegel, T. T.; Greco, E. C.; DePalma, J. L.; Starc, V.; Marthol, H.; Tutaj, M.; Buechner, S.; Axelrod, F. B.; Hilz, M. J.

2007-01-01

To identify accurate predictors for the risk of sudden death in patients with familial dysautonomia (FD). Ten-minute resting high-fidelity 12-lead ECGs were obtained from 14 FD patients and 14 age/gender-matched healthy subjects. Multiple conventional and advanced ECG parameters were studied for their ability to predict sudden death in FD over a subsequent 4.5-year period, including multiple indices of linear and non-linear heart rate variability (HRV); QT variability; waveform complexity; high frequency QRS; and derived Frank-lead parameters. Four of the 14 FD patients died suddenly during the follow-up period, usually with concomitant pulmonary disorder. The presence of low vagally-mediated HRV was the ECG finding most predictive of sudden death. Concomitant left ventricular hypertrophy and other ECG abnormalities such as increased QTc and JTc intervals, spatial QRS-T angles, T-wave complexity, and QT variability were also present in FD patients, suggesting that structural heart disease is fairly common in FD. Although excessive or unopposed cardiac vagal (relative to sympathetic) activity has been postulated as a contributor to sudden death in FD, the presence of low vagally-mediated HRV was paradoxically the best predictor of sudden death. However, we suggest that low vagally-mediated HRV be construed not as a direct cause of sudden death in FD, but rather as an effect of concurrent pathological processes, especially hypoxia due to pulmonary disorders and sleep apnea, that themselves increase the risk of sudden death in FD and simultaneously diminish HRV. We speculate that adenosine may play a role in sudden death in FD, possibly independently of vagal activity, and that adenosine inhibitors such as theophylline might therefore be useful as prophylaxis in this disorder.

Small-angle neutron scattering reveals the assembly mode and oligomeric architecture of TET, a large, dodecameric aminopeptidase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Appolaire, Alexandre; Girard, Eric; Colombo, Matteo

2014-11-01

The present work illustrates that small-angle neutron scattering, deuteration and contrast variation, combined with in vitro particle reconstruction, constitutes a very efficient approach to determine subunit architectures in large, symmetric protein complexes. In the case of the 468 kDa heterododecameric TET peptidase machine, it was demonstrated that the assembly of the 12 subunits is a highly controlled process and represents a way to optimize the catalytic efficiency of the enzyme. The specific self-association of proteins into oligomeric complexes is a common phenomenon in biological systems to optimize and regulate their function. However, de novo structure determination of these important complexesmore » is often very challenging for atomic-resolution techniques. Furthermore, in the case of homo-oligomeric complexes, or complexes with very similar building blocks, the respective positions of subunits and their assembly pathways are difficult to determine using many structural biology techniques. Here, an elegant and powerful approach based on small-angle neutron scattering is applied, in combination with deuterium labelling and contrast variation, to elucidate the oligomeric organization of the quaternary structure and the assembly pathways of 468 kDa, hetero-oligomeric and symmetric Pyrococcus horikoshii TET2–TET3 aminopeptidase complexes. The results reveal that the topology of the PhTET2 and PhTET3 dimeric building blocks within the complexes is not casual but rather suggests that their quaternary arrangement optimizes the catalytic efficiency towards peptide substrates. This approach bears important potential for the determination of quaternary structures and assembly pathways of large oligomeric and symmetric complexes in biological systems.« less

Molecular envelope and atomic model of an anti-terminated glyQS T-box regulator in complex with tRNAGly

PubMed Central

Chetnani, Bhaskar

2017-01-01

Abstract A T-box regulator or riboswitch actively monitors the levels of charged/uncharged tRNA and participates in amino acid homeostasis by regulating genes involved in their utilization or biosynthesis. It has an aptamer domain for cognate tRNA recognition and an expression platform to sense the charge state and modulate gene expression. These two conserved domains are connected by a variable linker that harbors additional secondary structural elements, such as Stem III. The structural basis for specific tRNA binding is known, but the structural basis for charge sensing and the role of other elements remains elusive. To gain new structural insights on the T-box mechanism, a molecular envelope was calculated from small angle X-ray scattering data for the Bacillus subtilis glyQS T-box riboswitch in complex with an uncharged tRNAGly. A structural model of an anti-terminated glyQS T-box in complex with its cognate tRNAGly was derived based on the molecular envelope. It shows the location and relative orientation of various secondary structural elements. The model was validated by comparing the envelopes of the wild-type complex and two variants. The structural model suggests that in addition to a possible regulatory role, Stem III could aid in preferential stabilization of the T-box anti-terminated state allowing read-through of regulated genes. PMID:28531275

Space shuttle: Stability and control effectiveness of the MDAC parametric delta canard booster at Mach 0.38. Volume 1: Canard parametric variations

NASA Technical Reports Server (NTRS)

Bradley, D.; Buchholz, R. E.

1971-01-01

A 0.015 scale model of a modified version of the MDAC space shuttle booster was tested in the Naval Ship Research and Development Center 7 x 10 foot transonic wind tunnel, to obtain force, static stability, and control effectiveness data. Data were obtained for a cruise Mach Number of 0.38, altitude of 10,000 ft, and Reynolds Number per foot of approximately 2 x one million. The model was tested through an angle of attack range of -4 deg to 15 deg at zero degree angle of sideslip, and at an angle of sideslip range of -6 deg to 6 deg at fixed angles of attack of 0 deg, 6 deg, and 15 deg. Other test variables were elevon deflections, canard deflections, aileron deflections, rudder deflections, wing dihedral angle, canard incidence angle, wing incidence angle, canard position, wing position, wing and canard control flap size and dorsal fin size.

Factors leading to the computer vision syndrome: an issue at the contemporary workplace.

PubMed

Izquierdo, Juan C; García, Maribel; Buxó, Carmen; Izquierdo, Natalio J

2007-01-01

Vision and eye related problems are common among computer users, and have been collectively called the Computer Vision Syndrome (CVS). An observational study in order to identify the risk factors leading to the CVS was done. Twenty-eight participants answered a validated questionnaire, and had their workstations examined. The questionnaire evaluated personal, environmental, ergonomic factors, and physiologic response of computer users. The distance from the eye to the computers' monitor (A), the computers' monitor height (B), and visual axis height (C) were measured. The difference between B and C was calculated and labeled as D. Angles of gaze to the computer monitor were calculated using the formula: angle=tan-1(D/A). Angles were divided into two groups: participants with angles of gaze ranging from 0 degree to 13.9 degrees were included in Group 1; and participants gazing at angles larger than 14 degrees were included in Group 2. Statistical analysis of the evaluated variables was made. Computer users in both groups used more tear supplements (as part of the syndrome) than expected. This association was statistically significant (p < 0.10). Participants in Group 1 reported more pain than participants in Group 2. Associations between the CVS and other personal or ergonomic variables were not statistically significant. Our findings show that the most important factor leading to the syndrome is the angle of gaze at the computer monitor. Pain in computer users is diminished when gazing downwards at angles of 14 degrees or more. The CVS remains an under estimated and poorly understood issue at the workplace. The general public, health professionals, the government, and private industries need to be educated about the CVS.

Factors leading to the Computer Vision Syndrome: an issue at the contemporary workplace.

PubMed

Izquierdo, Juan C; García, Maribel; Buxó, Carmen; Izquierdo, Natalio J

2004-01-01

Vision and eye related problems are common among computer users, and have been collectively called the Computer Vision Syndrome (CVS). An observational study in order to identify the risk factors leading to the CVS was done. Twenty-eight participants answered a validated questionnaire, and had their workstations examined. The questionnaire evaluated personal, environmental, ergonomic factors, and physiologic response of computer users. The distance from the eye to the computers' monitor (A), the computers' monitor height (B), and visual axis height (C) were measured. The difference between B and C was calculated and labeled as D. Angles of gaze to the computer monitor were calculated using the formula: angle=tan(-1)(D/ A). Angles were divided into two groups: participants with angles of gaze ranging from 0 degrees to 13.9 degrees were included in Group 1; and participants gazing at angles larger than 14 degrees were included in Group 2. Statistical analysis of the evaluated variables was made. Computer users in both groups used more tear supplements (as part of the syndrome) than expected. This association was statistically significant (p<0.10). Participants in Group 1 reported more pain than participants in Group 2. Associations between the CVS and other personal or ergonomic variables were not statistically significant. Our findings show that most important factor leading to the syndrome is the angle of gaze at the computer monitor. Pain in computer users is diminished when gazing downwards at angles of 14 degrees or more. The CVS remains an under estimated and poorly understood issue at the workplace. The general public, health professionals, the government, and private industries need to be educated about the CVS.

Analysis of naturalistic driving videos of fleet services drivers to estimate driver error and potentially distracting behaviors as risk factors for rear-end versus angle crashes.

PubMed

Harland, Karisa K; Carney, Cher; McGehee, Daniel

2016-07-03

The objective of this study was to estimate the prevalence and odds of fleet driver errors and potentially distracting behaviors just prior to rear-end versus angle crashes. Analysis of naturalistic driving videos among fleet services drivers for errors and potentially distracting behaviors occurring in the 6 s before crash impact. Categorical variables were examined using the Pearson's chi-square test, and continuous variables, such as eyes-off-road time, were compared using the Student's t-test. Multivariable logistic regression was used to estimate the odds of a driver error or potentially distracting behavior being present in the seconds before rear-end versus angle crashes. Of the 229 crashes analyzed, 101 (44%) were rear-end and 128 (56%) were angle crashes. Driver age, gender, and presence of passengers did not differ significantly by crash type. Over 95% of rear-end crashes involved inadequate surveillance compared to only 52% of angle crashes (P < .0001). Almost 65% of rear-end crashes involved a potentially distracting driver behavior, whereas less than 40% of angle crashes involved these behaviors (P < .01). On average, drivers spent 4.4 s with their eyes off the road while operating or manipulating their cell phone. Drivers in rear-end crashes were at 3.06 (95% confidence interval [CI], 1.73-5.44) times adjusted higher odds of being potentially distracted than those in angle crashes. Fleet driver driving errors and potentially distracting behaviors are frequent. This analysis provides data to inform safe driving interventions for fleet services drivers. Further research is needed in effective interventions to reduce the likelihood of drivers' distracting behaviors and errors that may potentially reducing crashes.

Controls on stream network branching angles, tested using landscape evolution models

NASA Astrophysics Data System (ADS)

Theodoratos, Nikolaos; Seybold, Hansjörg; Kirchner, James W.

2016-04-01

Stream networks are striking landscape features. The topology of stream networks has been extensively studied, but their geometry has received limited attention. Analyses of nearly 1 million stream junctions across the contiguous United States [1] have revealed that stream branching angles vary systematically with climate and topographic gradients at continental scale. Stream networks in areas with wet climates and gentle slopes tend to have wider branching angles than in areas with dry climates or steep slopes, but the mechanistic linkages underlying these empirical correlations remain unclear. Under different climatic and topographic conditions different runoff generation mechanisms and, consequently, transport processes are dominant. Models [2] and experiments [3] have shown that the relative strength of channel incision versus diffusive hillslope transport controls the spacing between valleys, an important geometric property of stream networks. We used landscape evolution models (LEMs) to test whether similar factors control network branching angles as well. We simulated stream networks using a wide range of hillslope diffusion and channel incision parameters. The resulting branching angles vary systematically with the parameters, but by much less than the regional variability in real-world stream networks. Our results suggest that the competition between hillslope and channeling processes influences branching angles, but that other mechanisms may also be needed to account for the variability in branching angles observed in the field. References: [1] H. Seybold, D. H. Rothman, and J. W. Kirchner, 2015, Climate's watermark in the geometry of river networks, Submitted manuscript. [2] J. T. Perron, W. E. Dietrich, and J. W. Kirchner, 2008, Controls on the spacing of first-order valleys, Journal of Geophysical Research, 113, F04016. [3] K. E. Sweeney, J. J. Roering, and C. Ellis, 2015, Experimental evidence for hillslope control of landscape scale, Science, 349(6243), 51-53.

The spinal posture of computing adolescents in a real-life setting

PubMed Central

2014-01-01

Background It is assumed that good postural alignment is associated with the less likelihood of musculoskeletal pain symptoms. Encouraging good sitting postures have not reported consequent musculoskeletal pain reduction in school-based populations, possibly due to a lack of clear understanding of good posture. Therefore this paper describes the variability of postural angles in a cohort of asymptomatic high-school students whilst working on desk-top computers in a school computer classroom and to report on the relationship between the postural angles and age, gender, height, weight and computer use. Methods The baseline data from a 12 month longitudinal study is reported. The study was conducted in South African school computer classrooms. 194 Grade 10 high-school students, from randomly selected high-schools, aged 15–17 years, enrolled in Computer Application Technology for the first time, asymptomatic during the preceding month, and from whom written informed consent were obtained, participated in the study. The 3D Posture Analysis Tool captured five postural angles (head flexion, neck flexion, cranio-cervical angle, trunk flexion and head lateral bend) while the students were working on desk-top computers. Height, weight and computer use were also measured. Individual and combinations of postural angles were analysed. Results 944 Students were screened for eligibility of which the data of 194 students are reported. Trunk flexion was the most variable angle. Increased neck flexion and the combination of increased head flexion, neck flexion and trunk flexion were significantly associated with increased weight and BMI (p = 0.0001). Conclusions High-school students sit with greater ranges of trunk flexion (leaning forward or reclining) when using the classroom computer. Increased weight is significantly associated with increased sagittal plane postural angles. PMID:24950887

Multislice frozen phonon high angle annular dark-field image simulation study of Mo-V-Nb-Te-O complex oxidation catalyst "M1".

PubMed

Blom, Douglas A

2012-01-01

Multislice frozen phonon calculations were performed on a model structure of a complex oxide which has potential use as an ammoxidation catalyst. The structure has 11 cation sites in the framework, several of which exhibit mixed Mo/V substitution. In this paper the sensitivity of high-angle annular dark-field (HAADF) imaging to partial substitution of V for Mo in this structure is reported. While the relationship between the average V content in an atom column and the HAADF image intensity is not independent of thickness, it is a fairly weak function of thickness suggesting that HAADF STEM imaging in certain cases can provide a useful starting point for Rietveld refinements of mixed occupancy in complex materials. The thermal parameters of the various cations and oxygen anions in the model affect the amount of thermal diffuse scattering and therefore the intensity in the HAADF images. For complex materials where the structure has been derived via powder Rietveld refinement, the uncertainty in the thermal parameters may limit the accuracy of HAADF image simulations. With the current interest in quantitative microscopy, simulations need to accurately describe the electron scattering to the very high angles often subtended by a HAADF detector. For this system approximately 15% of the scattering occurs above 200 mrad at 200 kV. To simulate scattering to such high angles, very fine sampling of the projected potential is necessary which increases the computational cost of the simulation. Copyright © 2011 Elsevier B.V. All rights reserved.

Space shuttle: Verification of transition reentry corridor at high angles of attack and determination of transition aerodynamic characteristics and subsonic aerodynamic characteristics at low angles of attack for the Boeing H-32 booster

NASA Technical Reports Server (NTRS)

Houser, J.; Johnson, L. J.; Oiye, M.; Runciman, W.

1972-01-01

Experimental aerodynamic investigations were made in a transonic wind tunnel on a 1/150-scale model of the Boeing H-32 space shuttle booster configuration. The purpose of the test was: (1) to verify the transonic reentry corridor at high angles of attack; (2) to determine the transonic aerodynamic characteristics; and (3) to determine the subsonic aerodynamic characteristics at low angles of attack. Test variables included configuration buildup, horizontal stabilizer settings of 0 and -20 deg, elevator deflections of 0 and -30 deg, and wing spoiler settings of 60 deg.

Experimental analysis of bidirectional reflectance distribution function cross section conversion term in direction cosine space.

PubMed

Butler, Samuel D; Nauyoks, Stephen E; Marciniak, Michael A

2015-06-01

Of the many classes of bidirectional reflectance distribution function (BRDF) models, two popular classes of models are the microfacet model and the linear systems diffraction model. The microfacet model has the benefit of speed and simplicity, as it uses geometric optics approximations, while linear systems theory uses a diffraction approach to compute the BRDF, at the expense of greater computational complexity. In this Letter, nongrazing BRDF measurements of rough and polished surface-reflecting materials at multiple incident angles are scaled by the microfacet cross section conversion term, but in the linear systems direction cosine space, resulting in great alignment of BRDF data at various incident angles in this space. This results in a predictive BRDF model for surface-reflecting materials at nongrazing angles, while avoiding some of the computational complexities in the linear systems diffraction model.

Fake ballistics and real explosions: field-scale experiments on the ejection and emplacement of volcanic bombs during vent-clearing explosive activity

NASA Astrophysics Data System (ADS)

Taddeucci, J.; Valentine, G.; Gaudin, D.; Graettinger, A. H.; Lube, G.; Kueppers, U.; Sonder, I.; White, J. D.; Ross, P.; Bowman, D. C.

2013-12-01

Ballistics - bomb-sized pyroclasts that travel from volcanic source to final emplacement position along ballistic trajectories - represent a prime source of volcanic hazard, but their emplacement range, size, and density is useful to inverse model key eruption parameters related to their initial ejection velocity. Models and theory, however, have so far focused on the trajectory of ballistics after leaving the vent, neglecting the complex dynamics of their initial acceleration phase in the vent/conduit. Here, we use field-scale buried explosion experiments to study the ground-to-ground ballistic emplacement of particles through their entire acceleration-deceleration cycle. Twelve blasts were performed at the University at Buffalo Large Scale Experimental Facility with a range of scaled depths (burial depth divided by the cubic root of the energy of the explosive charge) and crater configurations. In all runs, ballistic analogs were placed on the ground surface at variable distance from the vertical projection of the buried charge, resulting in variable ejection angle. The chosen analogs are tennis and ping-pong balls filled with different materials, covering a limited range of sizes and densities. The analogs are tracked in multiple high-speed and high-definition videos, while Particle Image Velocimetry is used to detail ground motion in response to the buried blasts. In addition, after each blast the emplacement position of all analog ballistics was mapped with respect to the blast location. Preliminary results show the acceleration history of ballistics to be quite variable, from very short and relatively simple acceleration coupled with ground motion, to more complex, multi-stage accelerations possibly affected not only by the initial ground motion but also by variable coupling with the gas-particle mixture generated by the blasts. Further analysis of the experimental results is expected to provide new interpretative tools for ballistic deposits and better hazard assessment, with particular emphasis for the case of vent-opening eruptions driven by explosive gas expansion beneath loose debris.

A high pressure study of calmodulin-ligand interactions using small-angle X-ray and elastic incoherent neutron scattering.

PubMed

Cinar, Süleyman; Al-Ayoubi, Samy; Sternemann, Christian; Peters, Judith; Winter, Roland; Czeslik, Claus

2018-01-31

Calmodulin (CaM) is a Ca 2+ sensor and mediates Ca 2+ signaling through binding of numerous target ligands. The binding of ligands by Ca 2+ -saturated CaM (holo-CaM) is governed by attractive hydrophobic and electrostatic interactions that are weakened under high pressure in aqueous solutions. Moreover, the potential formation of void volumes upon ligand binding creates a further source of pressure sensitivity. Hence, high pressure is a suitable thermodynamic variable to probe protein-ligand interactions. In this study, we compare the binding of two different ligands to holo-CaM as a function of pressure by using X-ray and neutron scattering techniques. The two ligands are the farnesylated hypervariable region (HVR) of the K-Ras4B protein, which is a natural binding partner of holo-CaM, and the antagonist trifluoperazine (TFP), which is known to inhibit holo-CaM activity. From small-angle X-ray scattering experiments performed up to 3000 bar, we observe a pressure-induced partial unfolding of the free holo-CaM in the absence of ligands, where the two lobes of the dumbbell-shaped protein are slightly swelled. In contrast, upon binding TFP, holo-CaM forms a closed globular conformation, which is pressure stable at least up to 3000 bar. The HVR of K-Ras4B shows a different binding behavior, and the data suggest the dissociation of the holo-CaM/HVR complex under high pressure, probably due to a less dense protein contact of the HVR as compared to TFP. The elastic incoherent neutron scattering experiments corroborate these findings. Below 2000 bar, pressure induces enhanced atomic fluctuations in both holo-CaM/ligand complexes, but those of the holo-CaM/HVR complex seem to be larger. Thus, the inhibition of holo-CaM by TFP is supported by a low-volume ligand binding, albeit this is not associated with a rigidification of the complex structure on the sub-ns Å-scale.

Wind-tunnel investigation to determine the low speed yawing stability derivatives of a twin jet fighter model at high angles of attack

NASA Technical Reports Server (NTRS)

Coe, P. L., Jr.; Newsom, W. A., Jr.

1974-01-01

An investigation was conducted to determine the low-speed yawing stability derivatives of a twin-jet fighter airplane model at high angles of attack. Tests were performed in a low-speed tunnel utilizing variable-curvature walls to simulate pure yawing motion. The results of the study showed that at angles of attack below the stall the yawing derivatives were essentially independent of the yawing velocity and sideslip angle. However, at angles of attack above the stall some nonlinear variations were present and the derivatives were strongly dependent upon sideslip angle. The results also showed that the rolling moment due to yawing was primarily due to the wing-fuselage combination, and that at angles of attack below the stall both the vertical and horizontal tails produced significant contributions to the damping in yaw. Additionally, the tests showed that the use of the forced-oscillation data to represent the yawing stability derivatives is questionable, at high angles of attack, due to large effects arising from the acceleration in sideslip derivatives.

[Primary branch size of Pinus koraiensis plantation: a prediction based on linear mixed effect model].

PubMed

Dong, Ling-Bo; Liu, Zhao-Gang; Li, Feng-Ri; Jiang, Li-Chun

2013-09-01

By using the branch analysis data of 955 standard branches from 60 sampled trees in 12 sampling plots of Pinus koraiensis plantation in Mengjiagang Forest Farm in Heilongjiang Province of Northeast China, and based on the linear mixed-effect model theory and methods, the models for predicting branch variables, including primary branch diameter, length, and angle, were developed. Considering tree effect, the MIXED module of SAS software was used to fit the prediction models. The results indicated that the fitting precision of the models could be improved by choosing appropriate random-effect parameters and variance-covariance structure. Then, the correlation structures including complex symmetry structure (CS), first-order autoregressive structure [AR(1)], and first-order autoregressive and moving average structure [ARMA(1,1)] were added to the optimal branch size mixed-effect model. The AR(1) improved the fitting precision of branch diameter and length mixed-effect model significantly, but all the three structures didn't improve the precision of branch angle mixed-effect model. In order to describe the heteroscedasticity during building mixed-effect model, the CF1 and CF2 functions were added to the branch mixed-effect model. CF1 function improved the fitting effect of branch angle mixed model significantly, whereas CF2 function improved the fitting effect of branch diameter and length mixed model significantly. Model validation confirmed that the mixed-effect model could improve the precision of prediction, as compare to the traditional regression model for the branch size prediction of Pinus koraiensis plantation.

Precision determination of electron scattering angle by differential nuclear recoil energy method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liyanage, N.; Saenboonruang, K.

2015-12-01

The accurate determination of the scattered electron angle is crucial to electron scattering experiments, both with open-geometry large-acceptance spectrometers and ones with dipole-type magnetic spectrometers for electron detection. In particular, for small central-angle experiments using dipole-type magnetic spectrometers, in which surveys are used to measure the spectrometer angle with respect to the primary electron beam, the importance of the scattering angle determination is emphasized. However, given the complexities of large experiments and spectrometers, the accuracy of such surveys is limited and insufficient to meet demands of some experiments. In this article, we present a new technique for determination of themore » electron scattering angle based on an accurate measurement of the primary beam energy and the principle of differential nuclear recoil. This technique was used to determine the scattering angle for several experiments carried out at the Experimental Hall A, Jefferson Lab. Results have shown that the new technique greatly improved the accuracy of the angle determination compared to surveys.« less

Precision Determination of Electron Scattering Angle by Differential Nuclear Recoil Energy Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liyanage, Nilanga; Saenboonruang, Kiadtisak

2015-09-01

The accurate determination of the scattered electron angle is crucial to electron scattering experiments, both with open-geometry large-acceptance spectrometers and ones with dipole-type magnetic spectrometers for electron detection. In particular, for small central-angle experiments using dipole-type magnetic spectrometers, in which surveys are used to measure the spectrometer angle with respect to the primary electron beam, the importance of the scattering angle determination is emphasized. However, given the complexities of large experiments and spectrometers, the accuracy of such surveys is limited and insufficient to meet demands of some experiments. In this article, we present a new technique for determination of themore » electron scattering angle based on an accurate measurement of the primary beam energy and the principle of differential nuclear recoil. This technique was used to determine the scattering angle for several experiments carried out at the Experimental Hall A, Jefferson Lab. Results have shown that the new technique greatly improved the accuracy of the angle determination compared to surveys.« less

Relationships of density, microfibril angle, and sound velocity with stiffness and strength in mature wood of Douglas-fir

Treesearch

B. Lachenbruch; G.R. Johnson; G.M. Downes; R. Evans

2010-01-01

The relative importance of density, acoustic velocity, and microfibril angle (MFA) for the prediction of stiffness (MOE) and strength (MOR) has not been well established for Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco). MOE and MOR of small clear specimens of mature wood were better predicted by density and velocity than by either variable...

Distribution functions for orbits trapped at the resonances in the Galactic disc

NASA Astrophysics Data System (ADS)

Monari, G.

2017-12-01

The present-day response of a Galactic disc stellar population to a non-axisymmetric perturbation of the potential has previously been computed through perturbation theory within the phase-space coordinates of the unperturbed axisymmetric system. Such an Eulerian linearized treatment however leads to singularities at resonances, which prevent quantitative comparisons with data. Monari et al. manage to capture the behaviour of the distribution function (DF) at a resonance in a Lagrangian approach, by averaging the Hamiltonian over fast angle variables and re-expressing the DF in terms of a new set of canonical actions and angles variables valid in the resonant region. They then follow the prescription of Binney (2016), assigning to the resonant DF the time average along the orbits of the axisymmetric DF expressed in the new set of actions and angles. This boils down to phase-mixing the DF in terms of the new angles, such that the DF for trapped orbits only depends on the new set of actions. This opens the way to quantitatively fitting the effects of the bar and spirals to Gaia data in terms of distribution functions in action space.

The use of the T1 sagittal angle in predicting overall sagittal balance of the spine.

PubMed

Knott, Patrick T; Mardjetko, Steven M; Techy, Fernando

2010-11-01

A balanced sagittal alignment of the spine has been shown to strongly correlate with less pain, less disability, and greater health status scores. To restore proper sagittal balance, one must assess the position of the occiput relative to the sacrum. The assessment of spinal balance preoperatively can be challenging, whereas predicting postoperative balance is even more difficult. This study was designed to evaluate and quantify multiple factors that influence sagittal balance. Retrospective analysis of existing spinal radiographs. A retrospective review of 52 adult spine patient records was performed. All patients had full-column digital radiographs that showed all the important skeletal landmarks necessary for accurate measurement. The average age of the patient was 53 years. Both genders were equally represented. The radiographs were measured using standard techniques to obtain the following parameters: scoliosis in the coronal plane; lordosis or kyphosis of the cervical, thoracic, and lumbar spine; the T1 sagittal angle (angle between a horizontal line and the superior end plate of T1); the angle of the dens in the sagittal plane; the angle of the dens in relation to the occiput; the sacral slope; the pelvic incidence; the femoral-sacral angle; and finally, the sagittal vertical axis (SVA) measured from both the dens of C2 and from C7. It was found that the SVA when measured from the dens was on average 16 mm farther forward than the SVA measured from C7 (p<.0001). The dens plumb line (SVA(dens)) was then used in the study. An analysis was done to examine the relationship between SVA(dens) and each of the other measurements. The T1 sagittal angle was found to have a moderate positive correlation (r=0.65) with SVA(dens), p<.0001, indicating that the amount of sagittal T1 tilt can be used as a good predictor of overall sagittal balance. When examining the other variables, it was found that cervical lordosis had a weak correlation (r=0.37) with SVA(dens) that was unexpected, given that cervical lordosis determines head position. Thoracic kyphosis also had a weak correlation (r=0.26) with SVA(C1), which was equally surprising. Lumbar lordosis had a slightly higher correlation (r=0.38), p=.006, than the cervical or thoracic spine. A multiple regression was run on the data to examine the relationship that all these independent variables have on SVA(dens). SPSS (SPSS, Inc., Chicago, IL, USA) was used to create a regression equation using the independent variables of T1 sagittal angle, cervical lordosis, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic incidence, and femoral-sacral angle and the dependent variable of SVA(dens). The model had a strong correlation (r=0.80, r(2)=0.64) and was statistically significant (p<.0001). The T1 sagittal angle was the variable that had the strongest correlation with the SVA(dens) Spearman r=0.65, p<.0001, followed by pelvic incidence, p=.002, and lumbar lordosis, p=.006. We also observed that when the T1 tilt was higher than 25°, all patients had at least 10 cm of positive sagittal imbalance. In addition, patients with negative sagittal balance had mostly low T1 tilt values, usually lower than 13°. The other variables were not shown to have a statically significant influence on SVA. This analysis shows that many factors influence the overall sagittal balance of the patient, but it may be the position of the pelvis and lower spine that have a stronger influence than the position of the upper back and neck. Unfortunately, to our knowledge, there are no studies to date that have established a normal sagittal T1 tilt angle. However, our analysis has shown that when the T1 tilt was higher than 25°, all patients had at least 10 cm of positive sagittal imbalance. It also showed that patients with negative sagittal balance had mostly low T1 tilt values, usually below 13° of angulation. The T1 sagittal angle is a measurement that may be very useful in evaluating sagittal balance, as it was the measure that most strongly correlated with SVA(dens). It has its great utility where long films cannot be obtained. Patients whose T1 tilt falls outside the range 13° to 25° should be sent for full-column radiographs for a complete evaluation of their sagittal balance. On the other hand, a T1 tilt within the above range does not guarantee a normal sagittal balance, and further investigation should be performed at the surgeon's discretion. Copyright © 2010 Elsevier Inc. All rights reserved.

Complexation and Structure Elucidation of the Axial Conformers of Mono- and (±)-trans-1,2-Disubstituted Cyclohexanes by Enantiopure Alleno-Acetylenic Cage Receptors.

PubMed

Gropp, Cornelius; Trapp, Nils

2018-04-25

Single crystal X-ray diffraction is a powerful method to unambiguously characterize the structure of molecules with atomic resolution. Herein, we review the molecular recognition of the (di)axial conformers of Mono- and (±)-trans-1,2-disubstituted cyclohexanes by enantiopure alleno-acetylenic cage receptors in solution and in the solid state. Single crystals of the host-guest complexes suitable for X-ray diffraction allow for the first time to study the dihedral angles of a series of Mono- and (±)-trans-1,2-disubstituted cyclohexanes in their (di)axial chair conformation. Theoretical studies indicate negligible influence of the host structure on the guest conformation, suggesting that the structural information obtained from the host-guest complexes give insight into the innate structures of Mono- and (±)-trans-1,2-disubstituted cyclohexanes. Strong deviation of the dihedral angles a,a(X-C(1)-C(2)-X) from the idealized 180° are observed, accompanied by substantial flattening of the ring dihedral angles ρ(X-C(1)-C(2)-C(3)).

A proposal for a new definition of the axial rotation angle of the shoulder joint.

PubMed

Masuda, Tadashi; Ishida, Akimasa; Cao, Lili; Morita, Sadao

2008-02-01

The Euler/Cardan angles are commonly used to define the motions of the upper arm with respect to the trunk. This definition, however, has a problem in that the angles of both the horizontal flexion/extension and the axial rotation of the shoulder joint become unstable at the gimbal-lock positions. In this paper, a new definition of the axial rotation angle was proposed. The proposed angle was stable over the entire range of the shoulder motion. With the new definition, the neutral position of the axial rotation agreed with that in the conventional anatomy. The advantage of the new definition was demonstrated by measuring actual complex motions of the shoulder with a three-dimensional motion capture system.

Adjoint-Based Design of Rotors Using the Navier-Stokes Equations in a Noninertial Reference Frame

NASA Technical Reports Server (NTRS)

Nielsen, Eric J.; Lee-Rausch, Elizabeth M.; Jones, William T.

2010-01-01

Optimization of rotorcraft flowfields using an adjoint method generally requires a time-dependent implementation of the equations. The current study examines an intermediate approach in which a subset of rotor flowfields are cast as steady problems in a noninertial reference frame. This technique permits the use of an existing steady-state adjoint formulation with minor modifications to perform sensitivity analyses. The formulation is valid for isolated rigid rotors in hover or where the freestream velocity is aligned with the axis of rotation. Discrete consistency of the implementation is demonstrated by using comparisons with a complex-variable technique, and a number of single- and multipoint optimizations for the rotorcraft figure of merit function are shown for varying blade collective angles. Design trends are shown to remain consistent as the grid is refined.

Adjoint-Based Design of Rotors using the Navier-Stokes Equations in a Noninertial Reference Frame

NASA Technical Reports Server (NTRS)

Nielsen, Eric J.; Lee-Rausch, Elizabeth M.; Jones, William T.

2009-01-01

Optimization of rotorcraft flowfields using an adjoint method generally requires a time-dependent implementation of the equations. The current study examines an intermediate approach in which a subset of rotor flowfields are cast as steady problems in a noninertial reference frame. This technique permits the use of an existing steady-state adjoint formulation with minor modifications to perform sensitivity analyses. The formulation is valid for isolated rigid rotors in hover or where the freestream velocity is aligned with the axis of rotation. Discrete consistency of the implementation is demonstrated using comparisons with a complex-variable technique, and a number of single- and multi-point optimizations for the rotorcraft figure of merit function are shown for varying blade collective angles. Design trends are shown to remain consistent as the grid is refined.

Portable Diode Pumped Femtosecond Lasers

DTIC Science & Technology

2007-03-01

second prism of the pair. [14, p.109] . . 41 2.34. GVD as a function of separation, in µm, of two N-SF18 Brewster angle prisms at a wavelength of...crystal showing Brewster angle of 54.6◦. . . . . . . 45 3.3. Index of refraction of LiSAF (blue) and BK7 (red) as a function of wavelength...separation, in µm, of two N-SF18 Brewster angle prisms at a wavelength of 1023 nm. 2.5 Summary The unique aspects of pulsing lasers can seem quite complex

A Non-Linear Simulation for an Autonomous Unmanned Air Vehicle

DTIC Science & Technology

1993-09-01

4D cos T cos 4D cos T r These equations can now be integrated to find the time history of the Euler angles . 2. Quaternions Another choice for the...is associated with the Euler angles . Quaternions haxe been in 15 use for quite some time. having been discovered by Euler in a search for complex... quaternions has the following advantages over Euler angles in repre- senting spatial orientation of a rigid body: "* Four states required to express the

Movement behavior of high-heeled walking: how does the nervous system control the ankle joint during an unstable walking condition?

PubMed

Alkjær, Tine; Raffalt, Peter; Petersen, Nicolas C; Simonsen, Erik B

2012-01-01

The human locomotor system is flexible and enables humans to move without falling even under less than optimal conditions. Walking with high-heeled shoes constitutes an unstable condition and here we ask how the nervous system controls the ankle joint in this situation? We investigated the movement behavior of high-heeled and barefooted walking in eleven female subjects. The movement variability was quantified by calculation of approximate entropy (ApEn) in the ankle joint angle and the standard deviation (SD) of the stride time intervals. Electromyography (EMG) of the soleus (SO) and tibialis anterior (TA) muscles and the soleus Hoffmann (H-) reflex were measured at 4.0 km/h on a motor driven treadmill to reveal the underlying motor strategies in each walking condition. The ApEn of the ankle joint angle was significantly higher (p<0.01) during high-heeled (0.38±0.08) than during barefooted walking (0.28±0.07). During high-heeled walking, coactivation between the SO and TA muscles increased towards heel strike and the H-reflex was significantly increased in terminal swing by 40% (p<0.01). These observations show that high-heeled walking is characterized by a more complex and less predictable pattern than barefooted walking. Increased coactivation about the ankle joint together with increased excitability of the SO H-reflex in terminal swing phase indicates that the motor strategy was changed during high-heeled walking. Although, the participants were young, healthy and accustomed to high-heeled walking the results demonstrate that that walking on high-heels needs to be controlled differently from barefooted walking. We suggest that the higher variability reflects an adjusted neural strategy of the nervous system to control the ankle joint during high-heeled walking.

Movement Behavior of High-Heeled Walking: How Does the Nervous System Control the Ankle Joint during an Unstable Walking Condition?

PubMed Central

Alkjær, Tine; Raffalt, Peter; Petersen, Nicolas C.; Simonsen, Erik B.

2012-01-01

The human locomotor system is flexible and enables humans to move without falling even under less than optimal conditions. Walking with high-heeled shoes constitutes an unstable condition and here we ask how the nervous system controls the ankle joint in this situation? We investigated the movement behavior of high-heeled and barefooted walking in eleven female subjects. The movement variability was quantified by calculation of approximate entropy (ApEn) in the ankle joint angle and the standard deviation (SD) of the stride time intervals. Electromyography (EMG) of the soleus (SO) and tibialis anterior (TA) muscles and the soleus Hoffmann (H-) reflex were measured at 4.0 km/h on a motor driven treadmill to reveal the underlying motor strategies in each walking condition. The ApEn of the ankle joint angle was significantly higher (p<0.01) during high-heeled (0.38±0.08) than during barefooted walking (0.28±0.07). During high-heeled walking, coactivation between the SO and TA muscles increased towards heel strike and the H-reflex was significantly increased in terminal swing by 40% (p<0.01). These observations show that high-heeled walking is characterized by a more complex and less predictable pattern than barefooted walking. Increased coactivation about the ankle joint together with increased excitability of the SO H-reflex in terminal swing phase indicates that the motor strategy was changed during high-heeled walking. Although, the participants were young, healthy and accustomed to high-heeled walking the results demonstrate that that walking on high-heels needs to be controlled differently from barefooted walking. We suggest that the higher variability reflects an adjusted neural strategy of the nervous system to control the ankle joint during high-heeled walking. PMID:22615997

High Speed Stream as driver of low latitude ionosphere variability: A study case in Brazilian sector

NASA Astrophysics Data System (ADS)

Nicoli Candido, C. M.; Batista, I. S.; Becker-Guedes, F.; Klausner, V.; da Silva, R.

2016-12-01

The solar activity period of solar cycle 23 was unusually long and quiet in comparison to other solar minima in last century. Several reports have analyzed its features and its impact under diverse points-of-view. In this work, we analyze the low latitude ionosphere behavior in Brazil and its response during this peculiar period. The ionospheric variation is analyzed through typical parameters such as vertical total electron content (VTEC), the peak height of F2 layer and its critical frequency, hmF2 and foF2, in 2008, around the southern crest of the Equatorial Ionization Anomaly (EIA), in Cachoeira Paulista (22.5º S, 45.0 ºW, mag. lat: 16 º S, dip angle: -32.3º) and at an equatorial station, São Luís (2.33º S, 44.2º W, dip angle: -6.7º). VTEC values present a semiannual variation pattern and two well-defined peaks in March and October. It was observed periodicities observed of 9, 13.5 and 27 days in VTEC and hmF2, mainly at the first and the second half of 2008. These periods match with the observed periods in solar and geomagnetic indexes such as Vsw, Kp and AE and are associated with occurrence of high speed streams (HSS) coming from solar coronal holes. A complex response of the low latitude ionosphere is observed, with prominent increases and decreases of VTEC at daytime during the interval of occurrence of HSSs. It is suggested that a combination of several factors such as prompt penetration of electric field, disturbed dynamo electric field, meridional winds, thermal expansion of thermosphere and composition changes of neutral atmosphere are responsible for the high day-to-day variability of the ionosphere.

A system of three-dimensional complex variables

NASA Technical Reports Server (NTRS)

Martin, E. Dale

1986-01-01

Some results of a new theory of multidimensional complex variables are reported, including analytic functions of a three-dimensional (3-D) complex variable. Three-dimensional complex numbers are defined, including vector properties and rules of multiplication. The necessary conditions for a function of a 3-D variable to be analytic are given and shown to be analogous to the 2-D Cauchy-Riemann equations. A simple example also demonstrates the analogy between the newly defined 3-D complex velocity and 3-D complex potential and the corresponding ordinary complex velocity and complex potential in two dimensions.

Movement within foot and ankle joint in children with spastic cerebral palsy: a 3-dimensional ultrasound analysis of medial gastrocnemius length with correction for effects of foot deformation

PubMed Central

2013-01-01

Background In spastic cerebral palsy (SCP), a limited range of motion of the foot (ROM), limits gait and other activities. Assessment of this limitation of ROM and knowledge of active mechanisms is of crucial importance for clinical treatment. Methods For a comparison between spastic cerebral palsy (SCP) children and typically developing children (TD), medial gastrocnemius muscle-tendon complex length was assessed using 3-D ultrasound imaging techniques, while exerting externally standardized moments via a hand-held dynamometer. Exemplary X-ray imaging of ankle and foot was used to confirm possible TD-SCP differences in foot deformation. Results SCP and TD did not differ in normalized level of excitation (EMG) of muscles studied. For given moments exerted in SCP, foot plate angles were all more towards plantar flexion than in TD. However, foot plate angle proved to be an invalid estimator of talocrural joint angle, since at equal foot plate angles, GM muscle-tendon complex was shorter in SCP (corresponding to an equivalent of 1 cm). A substantial difference remained even after normalizing for individual differences in tibia length. X-ray imaging of ankle and foot of one SCP child and two typically developed adults, confirmed that in SCP that of total footplate angle changes (0-4 Nm: 15°), the contribution of foot deformation to changes in foot plate angle (8) were as big as the contribution of dorsal flexion at the talocrural joint (7°). In typically developed individuals there were relatively smaller contributions (10 -11%) by foot deformation to changes in foot plate angle, indicating that the contribution of talocrural angle changes was most important. Using a new estimate for position at the talocrural joint (the difference between GM muscle–tendon complex length and tibia length, GM relative length) removed this effect, thus allowing more fair comparison of SCP and TD data. On the basis of analysis of foot plate angle and GM relative length as a function of externally applied moments, it is concluded that foot plate angle measurements underestimate angular changes at the talocrural joint when moving in dorsal flexion direction and overestimate them when moving in plantar flexion direction, with concomitant effects on triceps surae lengths. Conclusions In SCP children diagnosed with decreased dorsal ROM of the ankle joint, the commonly used measure (i.e. range of foot plate angle), is not a good estimate of rotation at the talocrural joint. since a sizable part of the movement of the foot (or foot plate) derives from internal deformation of the foot. PMID:24364826

Multiple incidence angle SIR-B experiment over Argentina

NASA Technical Reports Server (NTRS)

Cimino, Jobea; Casey, Daren; Wall, Stephen; Brandani, Aldo; Domik, Gitta; Leberl, Franz

1986-01-01

The Shuttle Imaging Radar (SIR-B), the second synthetic aperture radar (SAR) to fly aboard a shuttle, was launched on October 5, 1984. One of the primary goals of the SIR-B experiment was to use multiple incidence angle radar images to distinguish different terrain types through the use of their characteristic backscatter curves. This goal was accomplished in several locations including the Chubut Province of southern Argentina. Four descending image acquisitions were collected providing a multiple incidence angle image set. The data were first used to assess stereo-radargrammetric techniques. A digital elevation model was produced using the optimum pair of multiple incidence angle images. This model was then used to determine the local incidence angle of each picture element to generate curves of relative brightness vs. incidence angle. Secondary image products were also generated using the multi-angle data. The results of this work indicate that: (1) various forest species and various structures of a single species may be discriminated using multiple incidence angle radar imagery, and (2) it is essential to consider the variation in backscatter due to a variable incidence angle when analyzing and comparing data collected at varying frequencies and polarizations.

Labelling Angles: Care, Indifference and Mathematical Symbols

ERIC Educational Resources Information Center

Long, Julie

2011-01-01

In this article, I explore tensions of care in the context of school mathematics by examining two accounts of a classroom moment involving labelling an angle. In particular, I draw attention to how caring for students and caring for mathematical ideas interplay in complex ways by inquiring into the two accounts through ideas of care and…

Quadratic elongation: A quantitative measure of distortion in coordination polyhedra

USGS Publications Warehouse

Robinson, Kelly F.; Gibbs, G.V.; Ribbe, P.H.

1971-01-01

Quadratic elongation and the variance of bond angles are linearly correlated for distorted octahedral and tetrahedral coordination complexes, both of which show variations in bond length and bond angle. The quadratic elonga tion is dimensionless, giving a quantitative measure of polyhedral distortion which is independent of the effective size of the polyhedron.

Effects of volitional spine stabilization on lifting task in recurrent low back pain population.

PubMed

Haddas, Ram; Yang, James; Lieberman, Isador

2016-09-01

To examine the influence of volitional preemptive abdominal contraction (VPAC) and recurrent low back pain (rLBP) on trunk mechanics and neuromuscular control during a symmetric lifting task. A 2 × 2 crossover mixed design was used to examine the effects of VPAC and group. Thirty-seven healthy individuals and 32 rLBP individuals performed symmetric box lifting trials with and without VPAC to a 1-m height table 3D trunk, pelvis, and hip joint angle and electromyographic magnitude variables were obtained. Selected variables were analyzed using ANOVA. The VPAC induced differences in joint kinematics and muscle activity in rLBP and healthy subjects during symmetric lifting. A significant two-way interaction effect was observed for the semitendinosus activity. The VPAC increased external oblique muscle activity, reduced erector spinae and multifidus muscles activity, and induced greater trunk flexion angle, greater trunk side flexion angle, and greater hip flexion angle, and decreased pelvis obliquity angle in both groups. In addition, the rLBP subjects presented with a reduced external oblique and gluteus maximus muscle activity, greater erector spinae and multifidus muscles activity, and greater pelvis posterior tilt angle. Our results provide evidence that a VPAC strategy performed during symmetric lifting may potentially reduce exposure to biomechanical factors that can contribute to lumbar spine injury. The hamstring muscles may play an important role in achieving pelvic balance during the lifting maneuver. Incorporating the VPAC during dynamic stressful activities appears to help improve sensorimotor control and facilitate positioning of the lower extremities and the pelvis, while protecting the lumbar spine.

Relationships among measurements obtained by use of computed tomography and radiography and scores of cartilage microdamage in hip joints with moderate to severe joint laxity of adult dogs.

PubMed

Lopez, Mandi J; Lewis, Brooke P; Swaab, Megan E; Markel, Mark D

2008-03-01

To evaluate correlations among measurements on radiographic and computed tomography (CT) images with articular cartilage microdamage in lax hip joints of dogs. 12 adult mixed-breed hounds. Pelvic CT and radiography were performed. Hip joints were harvested following euthanasia. Orthopedic Foundation for Animals (OFA) and PennHIP radiograph reports were obtained. Norberg angle (NA) and radiographic percentage femoral head coverage (RPC) were determined. Center-edge angle (CEA), horizontal toit externe angle (HTEA), ventral acetabular sector angle (VASA), dorsal acetabular sector angle (DASA), horizontal acetabular sector angle (HASA), acetabular index (AI), and CT percentage femoral head coverage (CPC) were measured on 2-dimensional CT images. Femoral head-acetabular shelf percentage was measured on sagittal 3-dimensional CT (SCT) and transverse 3-dimensional CT (TCT) images. Light microscopy was used to score joint cartilage. Relationships of OFA confirmation and PennHIP osteoarthritis scores with radiography, CT, and cartilage variables and relationships of cartilage scores with radiography and CT measurements were evaluated with Spearman rank correlations. Pearson correlation was used for relationships of distraction index (DI) with radiography, CT, and cartilage variables. Significant relationships included PennHIP osteoarthritis score with cartilage score, CEA, HTEA, DASA, AI, CPC, and TCT; OFA confirmation score with cartilage score, NA, RPC, CEA, HTEA, DASA, AI, CPC, and TCT; cartilage score with NA, RPC, CEA, HTEA, DASA, HASA, AI, and TCT; and DI with cartilage score, CEA, HTEA, DASA, HASA, AI, and CPC. CT appeared to be a valuable imaging modality for predicting cartilage microdamage in canine hip joints.

Effects of Implantable Collamer Lens V4c Placement on Iridocorneal Angle Measurements by Fourier-Domain Optical Coherence Tomography.

PubMed

Fernández-Vigo, José Ignacio; Macarro-Merino, Ana; Fernández-Vigo, Cristina; Fernández-Vigo, José Ángel; Martínez-de-la-Casa, José María; Fernández-Pérez, Cristina; García-Feijóo, Julián

2016-02-01

To assess by Fourier-domain optical coherence tomography (FDOCT) changes produced in iridocorneal angle measurements in patients undergoing Visian Implantable Collamer Lens (ICL) V4c (STAAR Surgical AG) placement. Prospective interventional case series. In 50 eyes of 25 myopic subjects consecutively scheduled for ICL implant, FDOCT (RTVue; Optovue Inc) iridocorneal angle measurements were made before and 1 and 3 months after surgery. Trabecular-iris angle (TIA) and angle opening distance 500 μm anterior to the scleral spur (AOD500) were compared among the quadrants nasal, temporal, and inferior, and correlations with ocular variables including lens vault were examined. Preoperative TIA was 48.7 ± 8.7, 48.2 ± 8.7, and 48.7 ± 9.3 degrees for the nasal, temporal, and inferior quadrants, with no differences (P = 1.000). Following ICL implant, corresponding values fell to 31.2 ± 11.5, 30.0 ± 10.7, and 29.7 ± 8.1 degrees at 1 month postsurgery, indicating angle narrowing of 34%-42%, and to 30.6 ± 12.3, 30.1 ± 11.9, and 29.8 ± 12.3 degrees, respectively, at 3 months postsurgery. Angle measurements failed to vary between 1 month and 3 months postsurgery (P = .481). In 8 eyes, iridotrabecular contact attributable to surgery was observed. One month after surgery, vault measurements correlated with TIA (R = -.309; P = .048). Six variables were identified as predictors of TIA at 1 month postsurgery (R(2) = .907). Although considerable angle narrowing was detected 1 month after ICL V4c implant, this narrowing remained stable at 3 months postsurgery. Factors predictive of TIA could serve to identify suitable candidates for ICL placement. Copyright © 2016 Elsevier Inc. All rights reserved.

Reading angles in maps.

PubMed

Izard, Véronique; O'Donnell, Evan; Spelke, Elizabeth S

2014-01-01

Preschool children can navigate by simple geometric maps of the environment, but the nature of the geometric relations they use in map reading remains unclear. Here, children were tested specifically on their sensitivity to angle. Forty-eight children (age 47:15-53:30 months) were presented with fragments of geometric maps, in which angle sections appeared without any relevant length or distance information. Children were able to read these map fragments and compare two-dimensional to three-dimensional angles. However, this ability appeared both variable and fragile among the youngest children of the sample. These findings suggest that 4-year-old children begin to form an abstract concept of angle that applies both to two-dimensional and three-dimensional displays and that serves to interpret novel spatial symbols. © 2013 The Authors. Child Development © 2013 Society for Research in Child Development, Inc.

Berry phase and Hannay's angle in a quantum-classical hybrid system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, H. D.; Wu, S. L.; Yi, X. X.

2011-06-15

The Berry phase, which was discovered more than two decades ago, provides very deep insight into the geometric structure of quantum mechanics. Its classical counterpart, Hannay's angle, is defined if closed curves of action variables return to the same curves in phase space after a time evolution. In this paper we study the Berry phase and Hannay's angle in a quantum-classical hybrid system under the Born-Oppenheimer approximation. By the term quantum-classical hybrid system, we mean a composite system consists of a quantum subsystem and a classical subsystem. The effects of subsystem-subsystem couplings on the Berry phase and Hannay's angle aremore » explored. The results show that the Berry phase has been changed sharply by the couplings, whereas the couplings have a small effect on the Hannay's angle.« less

Contact- and distance-based principal component analysis of protein dynamics.

PubMed

Ernst, Matthias; Sittel, Florian; Stock, Gerhard

2015-12-28

To interpret molecular dynamics simulations of complex systems, systematic dimensionality reduction methods such as principal component analysis (PCA) represent a well-established and popular approach. Apart from Cartesian coordinates, internal coordinates, e.g., backbone dihedral angles or various kinds of distances, may be used as input data in a PCA. Adopting two well-known model problems, folding of villin headpiece and the functional dynamics of BPTI, a systematic study of PCA using distance-based measures is presented which employs distances between Cα-atoms as well as distances between inter-residue contacts including side chains. While this approach seems prohibitive for larger systems due to the quadratic scaling of the number of distances with the size of the molecule, it is shown that it is sufficient (and sometimes even better) to include only relatively few selected distances in the analysis. The quality of the PCA is assessed by considering the resolution of the resulting free energy landscape (to identify metastable conformational states and barriers) and the decay behavior of the corresponding autocorrelation functions (to test the time scale separation of the PCA). By comparing results obtained with distance-based, dihedral angle, and Cartesian coordinates, the study shows that the choice of input variables may drastically influence the outcome of a PCA.

Contact- and distance-based principal component analysis of protein dynamics

NASA Astrophysics Data System (ADS)

Ernst, Matthias; Sittel, Florian; Stock, Gerhard

2015-12-01

To interpret molecular dynamics simulations of complex systems, systematic dimensionality reduction methods such as principal component analysis (PCA) represent a well-established and popular approach. Apart from Cartesian coordinates, internal coordinates, e.g., backbone dihedral angles or various kinds of distances, may be used as input data in a PCA. Adopting two well-known model problems, folding of villin headpiece and the functional dynamics of BPTI, a systematic study of PCA using distance-based measures is presented which employs distances between Cα-atoms as well as distances between inter-residue contacts including side chains. While this approach seems prohibitive for larger systems due to the quadratic scaling of the number of distances with the size of the molecule, it is shown that it is sufficient (and sometimes even better) to include only relatively few selected distances in the analysis. The quality of the PCA is assessed by considering the resolution of the resulting free energy landscape (to identify metastable conformational states and barriers) and the decay behavior of the corresponding autocorrelation functions (to test the time scale separation of the PCA). By comparing results obtained with distance-based, dihedral angle, and Cartesian coordinates, the study shows that the choice of input variables may drastically influence the outcome of a PCA.

Relationship between mechanical factors and pelvic tilt in adults with and without low back pain.

PubMed

Król, Anita; Polak, Maciej; Szczygieł, Elżbieta; Wójcik, Paweł; Gleb, Klaudia

2017-01-01

The assessment of the lumbo-pelvic complex parameters is the basic procedure during the examination of the patients with low back pain syndrome (LBP). The aim of the study was to define the relationship between pelvic tilt and following factors: age, BMI, ability to activate deep abdominal muscles, iliopsoas and hamstrings muscles length, lumbar lordosis and thoracic kyphosis angle value, in adults with and without low back pain. The study covered a group of 60 female students aged 20-26. Average age was 22 years ± 1.83 (median = 22.5 years). In order to investigate the relationship between the anterior pelvic tilt and the analysed variables, simple linear regression and multiple linear regression were carried out. Individuals with and without pain differed significantly in terms of age, p < 0.001. There was a statistically significant relationship between the anterior pelvic tilt and the LBP (R2 = 0.07, p = 0.049) and the lumbar lordosis (R2 = 0.13, p = 0.02). The position of the pelvis depends on age, angle value of lumbar lordosis and BMI. Individuals with and without pain differed significantly in terms of the anterior pelvic tilt. The risk of LBP incidence increased with age in the study group.

A mock heart engineered with helical aramid fibers for in vitro cardiovascular device testing.

PubMed

Jansen-Park, So-Hyun; Hsu, Po-Lin; Müller, Indra; Steinseifer, Ulrich; Abel, Dirk; Autschbach, Rüdiger; Rossaint, Rolf; Schmitz-Rode, Thomas

2017-04-01

Mock heart circulation loops (MHCLs) serve as in-vitro platforms to investigate the physiological interaction between circulatory systems and cardiovascular devices. A mock heart (MH) engineered with silicone walls and helical aramid fibers, to mimic the complex contraction of a natural heart, has been developed to advance the MHCL previously developed in our group. A mock aorta with an anatomical shape enables the evaluation of a cannulation method for ventricular assist devices (VADs) and investigation of the usage of clinical measurement systems like pressure-volume catheters. Ventricle and aorta molds were produced based on MRI data and cast with silicone. Aramid fibers were layered in the silicone ventricle to reproduce ventricle torsion. A rotating hollow shaft was connected to the apex enabling the rotation of the MH and the connection of a VAD. Silicone wall thickness, aramid fiber angle and fiber pitch were varied to generate different MH models. All MH models were placed in a tank filled with variable amounts of water and air simulating the compliance. In this work, physiological ventricular torsion angles (15°-26°) and physiological pressure-volume loops were achieved. This MHCL can serve as a comprehensive testing platform for cardiovascular devices, such as artificial heart valves and cannulation of VADs.

Humeral torsion revisited: a functional and ontogenetic model for populational variation.

PubMed

Cowgill, Libby W

2007-12-01

Anthropological interest in humeral torsion has a long history, and several functional explanations for observed variation in the orientation of the humeral head have been proposed. Recent clinical studies have revived this topic by linking patterns of humeral torsion to habitual activities such as overhand throwing. However, the precise functional implications and ontogenetic history of humeral torsion remain unclear. This study examines the ontogeny of humeral torsion in a large sample of primarily immature remains from six different skeletal collections (n = 407). The results of this research confirm that humeral torsion displays consistent developmental variation within all populations of growing children; neonates display relatively posteriorly oriented humeral heads, and the level of torsion declines steadily into adulthood. As in adults, variation in the angle of humeral torsion in immature individuals varies by population, and these differences arise early in development. However, when examined in the context of the developing muscles of the shoulder complex, it becomes apparent that variation in the angle of humeral torsion is not necessarily related to specific habitual activities. Variability in this feature is more likely caused by a generalized functional imbalance between muscles of medial and lateral rotation that can be produced by a wide variety of upper limb activity patterns during growth. (c) 2007 Wiley-Liss, Inc.

Structure determination of a key intermediate of the enantioselective Pd complex catalyzed allylic substitution reaction

PubMed

Junker; Reif; Steinhagen; Junker; Felli; Reggelin; Griesinger

2000-09-01

The structure of a catalytic intermediate with important implications for the interpretation of the stereochemical outcome of the palladium complex catalyzed allylic substitution with phosphino-oxazoline (PHOX) ligands is determined by liquid state NMR. The complex displays a novel structure that is highly distorted compared with other palladium eta2-olefin complexes known so far. The structure has been determined from nuclear overhauser data (NOE), scalar coupling constants, and long range projection angle restraints derived from dipole dipole cross-correlated relaxation of multiple quantum coherence. The latter restraints have been implemented into a distance geometry protocol. The projection angle restraints yield a higher precision in the determination of the relative orientation of the two molecular moieties and are essential to provide an exact structural definition of the olefinic part of the catalytic intermediate with respect to the ligand.

Synthesis and crystal structure of the iridium(I) carbene complex with a pair of hydrogen wing tips

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, H.-Y.; Chen, Z.-M.; Wang, Y.

The iridium(I) cyclooctadiene complex with two (3-tert-butylimidazol-2-ylidene) ligands [(H-Im{sup t}Bu){sub 2}Ir(COD)]{sup +}PF{sub 6}{sup −} (C{sub 22}H{sub 32}PF{sub 6}IrN{sub 4}) has been prepared, and its crystal structure is determined by X-ray diffraction. Complex exhibits slightly distorted square planar configurations around the metal atom, which is coordinated by two H-Im{sup t}Bu ligands and one cyclooctadiene group. The new iridium carbene complex has a pair of hydrogen wing tips. The Ir−C{sub carbene} bond lengths are 2.066(5) and 2.052(5) Å, and the bond angle C−Ir−C between these bonds is 95.54(19)°. The dihedral angle between two imidazol-2-ylidene rings is 86.42°.

Lipid based drug delivery systems: Kinetics by SANS

NASA Astrophysics Data System (ADS)

Uhríková, D.; Teixeira, J.; Hubčík, L.; Búcsi, A.; Kondela, T.; Murugova, T.; Ivankov, O. I.

2017-05-01

N,N-dimethyldodecylamine-N-oxide (C12NO) is a surfactant that may exist either in a neutral or protonated form depending on the pH of aqueous solutions. Using small angle X-ray diffraction (SAXD) we demonstrate structural responsivity of C12NO/dioleoylphospha-tidylethanolamine (DOPE)/DNA complexes designed as pH sensitive gene delivery vectors. Small angle neutron scattering (SANS) was employed to follow kinetics of C12NO protonization and DNA binding into C12NO/DOPE/DNA complexes in solution of 150 mM NaCl at acidic condition. SANS data analyzed using paracrystal lamellar model show the formation of complexes with stacking up to ∼32 bilayers, spacing ∼ 62 Å, and lipid bilayer thickness ∼37 Å in 3 minutes after changing pH from 7 to 4. Subsequent structural reorganization of the complexes was observed along 90 minutes of SANS mesurements.

A New Low Complexity Angle of Arrival Algorithm for 1D and 2D Direction Estimation in MIMO Smart Antenna Systems

PubMed Central

Al-Sadoon, Mohammed A. G.; Zuid, Abdulkareim; Jones, Stephen M. R.; Noras, James M.

2017-01-01

This paper proposes a new low complexity angle of arrival (AOA) method for signal direction estimation in multi-element smart wireless communication systems. The new method estimates the AOAs of the received signals directly from the received signals with significantly reduced complexity since it does not need to construct the correlation matrix, invert the matrix or apply eigen-decomposition, which are computationally expensive. A mathematical model of the proposed method is illustrated and then verified using extensive computer simulations. Both linear and circular sensors arrays are studied using various numerical examples. The method is systematically compared with other common and recently introduced AOA methods over a wide range of scenarios. The simulated results show that the new method has several advantages in terms of reduced complexity and improved accuracy under the assumptions of correlated signals and limited numbers of snapshots. PMID:29140313

A New Low Complexity Angle of Arrival Algorithm for 1D and 2D Direction Estimation in MIMO Smart Antenna Systems.

PubMed

Al-Sadoon, Mohammed A G; Ali, Nazar T; Dama, Yousf; Zuid, Abdulkareim; Jones, Stephen M R; Abd-Alhameed, Raed A; Noras, James M

2017-11-15

This paper proposes a new low complexity angle of arrival (AOA) method for signal direction estimation in multi-element smart wireless communication systems. The new method estimates the AOAs of the received signals directly from the received signals with significantly reduced complexity since it does not need to construct the correlation matrix, invert the matrix or apply eigen-decomposition, which are computationally expensive. A mathematical model of the proposed method is illustrated and then verified using extensive computer simulations. Both linear and circular sensors arrays are studied using various numerical examples. The method is systematically compared with other common and recently introduced AOA methods over a wide range of scenarios. The simulated results show that the new method has several advantages in terms of reduced complexity and improved accuracy under the assumptions of correlated signals and limited numbers of snapshots.

Governing Influence of Thermodynamic and Chemical Equilibria on the Interfacial Properties in Complex Fluids.

PubMed

Harikrishnan, A R; Dhar, Purbarun; Gedupudi, Sateesh; Das, Sarit K

2018-04-12

We propose a comprehensive analysis and a quasi-analytical mathematical formalism to predict the surface tension and contact angles of complex surfactant-infused nanocolloids. The model rests on the foundations of the interaction potentials for the interfacial adsorption-desorption dynamics in complex multicomponent colloids. Surfactant-infused nanoparticle-laden interface problems are difficult to deal with because of the many-body interactions and interfaces involved at the meso-nanoscales. The model is based on the governing role of thermodynamic and chemical equilibrium parameters in modulating the interfacial energies. The influence of parameters such as the presence of surfactants, nanoparticles, and surfactant-capped nanoparticles on interfacial dynamics is revealed by the analysis. Solely based on the knowledge of interfacial properties of independent surfactant solutions and nanocolloids, the same can be deduced for complex surfactant-based nanocolloids through the proposed approach. The model accurately predicts the equilibrium surface tension and contact angle of complex nanocolloids available in the existing literature and present experimental findings.

Study of InGaAs-based modulation doped field effect transistor structures using variable-angle spectroscopic ellipsometry

NASA Technical Reports Server (NTRS)

Alterovitz, S. A.; Sieg, R. M.; Yao, H. D.; Snyder, P. G.; Woollam, J. A.; Pamulapati, J.; Bhattacharya, P. K.; Sekula-Moise, P. A.

1991-01-01

Variable-angle spectroscopic ellipsometry was used to estimate the thicknesses of all layers within the optical penetration depth of InGaAs-based modulation doped field effect transistor structures. Strained and unstrained InGaAs channels were made by molecular beam epitaxy (MBE) on InP substrates and by metal-organic chemical vapor deposition on GaAs substrates. In most cases, ellipsometrically determined thicknesses were within 10% of the growth-calibration results. The MBE-made InGaAs strained layers showed large strain effects, indicating a probable shift in the critical points of their dielectric function toward the InP lattice-matched concentration.

Computer program for design analysis of radial-inflow turbines

NASA Technical Reports Server (NTRS)

Glassman, A. J.

1976-01-01

A computer program written in FORTRAN that may be used for the design analysis of radial-inflow turbines was documented. The following information is included: loss model (estimation of losses), the analysis equations, a description of the input and output data, the FORTRAN program listing and list of variables, and sample cases. The input design requirements include the power, mass flow rate, inlet temperature and pressure, and rotational speed. The program output data includes various diameters, efficiencies, temperatures, pressures, velocities, and flow angles for the appropriate calculation stations. The design variables include the stator-exit angle, rotor radius ratios, and rotor-exit tangential velocity distribution. The losses are determined by an internal loss model.

Determining and Controlling the Magnesium Composition in CdTe/CdMgTe Heterostructures

DOE PAGES

LeBlanc, E. G.; Edirisooriya, M.; Ogedengbe, O. S.; ...

2017-06-05

The relationships between Mg composition, band gap, and lattice characteristics are investigated for Cd 1-xMg xTe barrier layers using a combination of cathodoluminescence, energy dispersive x-ray spectroscopy, variable angle spectral ellipsometry, and atom probe tomography. The use of a simplified, yet accurate, variable angle spectral ellipsometry analysis is shown to be appropriate for fast determination of composition in thin Cd 1-xMg xTe layers. The validity of using high-resolution x-ray diffraction for CdTe/Cd 1-xMg xTe double heterostructures is discussed. Furthermore, the stability of CdTe/Cd 1-xMg xTe heterostructures are investigated with respect to thermal processing.

Determining and Controlling the Magnesium Composition in CdTe/CdMgTe Heterostructures

DOE Office of Scientific and Technical Information (OSTI.GOV)

LeBlanc, E. G.; Edirisooriya, M.; Ogedengbe, O. S.

The relationships between Mg composition, band gap, and lattice characteristics are investigated for Cd 1-xMg xTe barrier layers using a combination of cathodoluminescence, energy dispersive x-ray spectroscopy, variable angle spectral ellipsometry, and atom probe tomography. The use of a simplified, yet accurate, variable angle spectral ellipsometry analysis is shown to be appropriate for fast determination of composition in thin Cd 1-xMg xTe layers. The validity of using high-resolution x-ray diffraction for CdTe/Cd 1-xMg xTe double heterostructures is discussed. Furthermore, the stability of CdTe/Cd 1-xMg xTe heterostructures are investigated with respect to thermal processing.

Inlet-engine matching for SCAR including application of a bicone variable geometry inlet

NASA Technical Reports Server (NTRS)

Wasserbauer, J. F.; Gerstenmaier, W. H.

1978-01-01

Airflow characteristics of variable cycle engines (VCE) designed for Mach 2.32 can have transonic airflow requirements as high as 1.6 times the cruise airflow. This is a formidable requirement for conventional, high performance, axisymmetric, translating centerbody mixed compression inlets. An alternate inlet is defined, where the second cone of a two cone center body collapses to the initial cone angle to provide a large off-design airflow capability, and incorporates modest centerbody translation to minimize spillage drag. Estimates of transonic spillage drag are competitive with those of conventional translating centerbody inlets. The inlet's cruise performance exhibits very low bleed requirements with good recovery and high angle of attack capability.

The influence of slope-angle ratio on the dynamics of granular flows: insights from laboratory experiments

NASA Astrophysics Data System (ADS)

Sulpizio, R.; Castioni, D.; Rodriguez-Sedano, L. A.; Sarocchi, D.; Lucchi, F.

2016-11-01

Laboratory experiments on granular flows using natural material were carried out in order to investigate the behaviour of granular flows passing over a break in slope. Sensors in the depositional area recorded the flow kinematics, while video footage permitted reconstruction of the deposit formation, which allowed investigation of the deposit shape as a function of the change in slope. We defined the slope-angle ratio as the proportion between slope angle in the depositional area and that of the channel. When the granular flow encounters the break in slope part of the flow front forms a bouncing clast zone due to elastic impact with the expansion box floor. During this process, part of the kinetic energy of the dense granular flow is transferred to elutriating fine ash, which subsequently forms turbulent ash cloud accompanying the granular flow until it comes to rest. Morphometric analysis of the deposits shows that they are all elliptical, with an almost constant minor axis and a variable major axis. The almost constant value of the minor axis relates to the spreading angle of flow at the end of the channel, which resembles the basal friction angle of the material. The variation of the major axis is interpreted to relate to the effect of competing inertial and frictional forces. This effect also reflects the partitioning of centripetal and tangential velocities, which changes as the flow passes over the break in slope. After normalization, morphometric data provided empirical relationships that highlight the dependence of runout from the product of slope-angle ratio and the difference in height between granular material release and deposit. The empirical relationships were tested against the runouts of hot avalanches formed during the 1944 ad eruption at Vesuvius, with differences among actual and calculated values are between 1.7 and 15 %. Velocity measurements of laboratory granular flows record deceleration paths at different breaks in slope. When normalized, the velocity data show third-order polynomial fit, highlighting a complex behaviour involving interplay between inertial and frictional forces. The theoretical velocity decays were tested against the data published for volcaniclastic debris flows of the 5-6 May 1998 event in the Sarno area. The comparison is very good for non-channelized debris flows, with significant differences between actual and calculated velocities for the channelized debris flows.

Wide-Angle Refraction Tomographic Inversion of Mid Cayman Spreading Center and its Oceanic Core Complex, CaySEIS Experiment

NASA Astrophysics Data System (ADS)

Harding, J.; Van Avendonk, H. J.; Hayman, N. W.; Grevemeyer, I.; Peirce, C.; Dannowski, A.; Papenberg, C. A.

2015-12-01

The CaySEIS experiment, conducted in April 2015, is a multi-national collaborative seismic study of the Mid Cayman Spreading Center (MCSC), an ultra-slow spreading center [15 mm/yr fr] in the Caribbean Sea. Ultra-slow spreading centers are thought to have very thin crust and a paucity of magmatism due to cooler mantle conditions. However, the suggestion that gabbro-cored oceanic core complexes (OCCs), volcanic deposits, and multiple layers of hydrothermal vents are widespread in the MCSC and other ultra-slow spreading centers has led to questions about the relationship between seafloor spreading rates and magmatism. To investigate this further, we conducted the CaySEIS experiment, with five wide-angle seismic refraction lines parallel and perpendicular to the neovolcanic zone. This analysis is based on two east-west oriented 100-km-long seismic refraction lines, which were each occupied by 18 ocean bottom seismometers. Line 2 lies across the central MCSC and an OCC called Mt. Dent. Line 3 crosses the northern end of the MCSC near the Oriente Transform Zone. With the wide-angle OBS data we can image the seismic velocity structure of Mt. Dent and distinguish between two models of OCCs - either Mt. Dent is composed of mostly gabbro with peridotite lenses identified by a low velocity gradient, or it is composed of mostly peridotite with gabbroic bodies identified by a constant velocity gradient. The crustal structure of both lines gives more insight into the asymmetry of the MCSC and the style of seafloor spreading to the east vs. the west. The 2-D velocity models reveal Mt. Dent has thick crust of 8 km with a low velocity gradient, supporting the magmatic gabbroic origin of OCCs. The surrounding crust to the west of the MCSC is highly variable, with areas of very thin crust. The crust to the east of the MCSC has an approximately constant thickness of 4 km. The development of OCCs may contribute to the crustal heterogeneity of ultra-slow spreading centers.

Frontal Changes in the Lower Face After Clockwise Rotation of the Maxillomandibular Complex Without Perisurgical Orthodontic Treatment in Angle Class I and Skeletal Class III Women.

PubMed

Lee, Sang Woo; Cho, Jeongmok; Kim, Kikap; Ahn, Seung Hyun

2017-06-01

Orthognathic surgery has become more popular to slenderize a wide lower face and to improve facial esthetics in Asian patients with normal occlusion. Clockwise rotation (CR) of the maxillomandibular complex (MMC) steepens the mandibular plane. This study performed a quantitative analysis on the influence of CR on slenderness of the lower face from the frontal view. This retrospective study included 36 female patients with Angle Class I occlusion and skeletal Class III pattern. The subjects underwent CR of the MMC without perioperative orthodontic treatment and change in the occlusion only for the purpose of esthetic improvement. Linear and angular variables were measured on a cephalogram and three-dimensional computed tomography (3D CT) obtained before and at least 6 months after surgery. Data were analyzed using paired t tests and Spearman correlations. Univariate regression analysis was used to predict the postoperative change according to the amount of posterior impaction. The mean posterior impaction was 3.81 mm. All mandibular plane angle (MPA) measurements were increased (ranged from 5.69° to 13.12°, p < 0.001), exhibiting a significant correlation with the amount of posterior impaction. Bigonial width measurements were decreased after surgery (ranged from 4.97 to 5.51 mm, p < 0.001). Among the MPAs derived from the 3D CT, the coronal projection from the frontal view exhibited a discrepancy between right and left side. The changes in linear and angular measurements in this study indicate that the lower face becomes narrower and more slender as the MMC rotates in a clockwise direction. Orthognathic surgery with CR has the advantage of increasing the MPAs and obtaining natural soft tissue contouring while minimizing the amount of bone resection. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266c .

Aerodynamics of an Axisymmetric Missile Concept Having Cruciform Strakes and In-Line Tail Fins From Mach 0.60 to 4.63

NASA Technical Reports Server (NTRS)

Allen, Jerry M.

2005-01-01

An experimental study has been performed to develop a large force and moment aerodynamic data set on a slender axisymmetric missile configuration having cruciform strakes and in-line control tail fins. The data include six-component balance measurements of the configuration aerodynamics and three-component measurements on all four tail fins. The test variables include angle of attack, roll angle, Mach number, model buildup, strake length, nose size, and tail fin deflection angles to provide pitch, yaw, and roll control. Test Mach numbers ranged from 0.60 to 4.63. The entire data set is presented on a CD-ROM that is attached to this paper. The CD-ROM also includes extensive plots of both the six-component configuration data and the three-component tail fin data. Selected samples of these plots are presented in this paper to illustrate the features of the data and to investigate the effects of the test variables.

Aerodynamics of an Axisymmetric Missile Concept Having Cruciform Strakes and In-Line Tail Fins From Mach 0.60 to 4.63, Supplement

NASA Technical Reports Server (NTRS)

Allen, Jerry M.

2005-01-01

An experimental study has been performed to develop a large force and moment aerodynamic data set on a slender axisymmetric missile configuration having cruciform strakes and in-line control tail fins. The data include six-component balance measurements of the configuration aerodynamics and three-component measurements on all four tail fins. The test variables include angle of attack, roll angle, Mach number, model buildup, strake length, nose size, and tail fin deflection angles to provide pitch, yaw, and roll control. Test Mach numbers ranged from 0.60 to 4.63. The entire data set is presented on a CD-ROM that is attached to this paper. The CD-ROM also includes extensive plots of both the six-component configuration data and the three-component tail fin data. Selected samples of these plots are presented in this paper to illustrate the features of the data and to investigate the effects of the test variables.

Influence of velocity on variability in gait kinematics: implications for recognition in forensic science.

PubMed

Yang, Sylvia X M; Larsen, Peter K; Alkjaer, Tine; Lynnerup, Niels; Simonsen, Erik B

2014-09-01

Closed circuit television (CCTV) footage is often available from crime scenes and may be used to compare perpetrators with suspects. Usually, the footage comprises incomplete gait cycles at different velocities, making gait pattern identification from crimes difficult. This study investigated the concurrence of joint angles throughout a gait cycle at three different velocities (3.0, 4.5, 6.0 km/h). Six datasets at each velocity were collected from 16 men. A variability range VR throughout the gait cycle at each velocity for each joint angle for each person was calculated. The joint angles at each velocity were compared pairwise, and whenever this showed values within the VR of this velocity, the case was positive. By adding the positives throughout the gait cycle, phases with high and low concurrences were located; peak concurrence was observed at mid-stance phase. Striving for the same velocity for the suspect and perpetrator is recommended. © 2014 American Academy of Forensic Sciences.

Predictive model of third molar eruption after second molar extraction.

PubMed

De-la-Rosa-Gay, Cristina; Valmaseda-Castellón, Eduard; Gay-Escoda, Cosme

2010-03-01

Extraction of second permanent molars is an option for providing space in orthodontic treatment. Although many articles have described its impact on the outcome, there are few data on the prognosis of the eruption of the adjacent third molars. The aims of this investigation were to provide predictive models of eruption of third molars after second permanent molar extraction and to validate them. A total of 48 patients (ages, 11-23 years) who had 128 second permanent molars (54 maxillary, 74 mandibular) extracted during orthodontic treatment were followed until eruption of the third molars was complete. A lineal regression model predicted the final angle of the third molars with the permanent first molar by using the variables of initial angle, jaw, and the developmental stage of the third molar. A logistic regression model predicted the probability of correct eruption by using the variables of initial angle, jaw, sex, age, and the developmental stage of the third molar. 2010 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

The aerodynamic characteristics of large angled cones with retrorockets

NASA Technical Reports Server (NTRS)

Jarvinen, P. O.; Adams, R. H.

1970-01-01

Analytical and experimental phases of the subject investigation are described. The analytical program for the single jet determines the terminal shock location, the jet boundary, the interface profile, the bow shock profile, the shear layer growth and the dead air region pressure. The experimental program described was conducted over the range from free stream Mach 0.4 to 2.0 at angles-of-attack up to 18 deg and at thrusting coefficients up to C sub T = T/q sub infinity A sub m = 30. Variables investigated included aeroshell angle, number of nozzles, engine thrust, size of nozzles, nozzle throttling and gas composition. The influence of these variables on the aeroshell stability, drag, and loads was determined by integrating pressure measurements on the aeroshell. The total system forces consist of components due to pure thrust and components due to pressure on the aeroshell arising from the jet-free stream interaction. Shadowgraphs provided flow field geometries which proved to be within 10% of those predicted analytically.

Polarization swings reveal magnetic energy dissipation in blazars

DOE PAGES

Zhang, Haocheng; Chen, Xuhui; Böttcher, Markus; ...

2015-05-01

The polarization signatures of blazar emissions are known to be highly variable. In addition to small fluctuations of the polarization angle around a mean value, large (≳ 180°) polarization angle swings are observed. We suggest that such phenomena can be interpreted as arising from light-travel-time effects within an underlying axisymmetric emission region. We present the first simultaneous fitting of the multi-wavelength spectrum, variability, and time-dependent polarization features of a correlated optical and gamma-ray flaring event of the prominent blazar 3C279, which was accompanied by a drastic change in its polarization signatures. This unprecedented combination of spectral, variability, and polarization informationmore » in a coherent physical model allows us to place stringent constraints on the particle acceleration and magnetic-field topology in the relativistic jet of a blazar, strongly favoring a scenario in which magnetic energy dissipation is the primary driver of the flare event.« less

Effects of drilling variables on burr properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gillespie, L.K.

1976-09-01

An investigation utilizing 303Se stainless steel, 17-4PH stainless steel, 1018 steel, and 6061-T6 aluminum was conducted to determine the influence of drilling variables in controlling burr size to minimize burr-removal cost and improve the quality and reliability of parts for small precision mechanisms. Burr thickness can be minimized by reducing feedrate and cutting velocity, and by using drills having high helix angles. High helix angles reduce burr thickness, length, and radius, while most other variables reduce only one of these properties. Radial-lip drills minimize burrs from 303Se stainless steel when large numbers of holes are drilled; this material stretches 10more » percent before drill-breakthrough. Entrance burrs can be minimized by the use of subland drills at a greatly increased tool cost. Backup-rods used in cross-drilled holes may be difficult to remove and may scratch the hole walls.« less

Variability and robustness of scatterers in HRR/ISAR ground target data and its influence on the ATR performance

NASA Astrophysics Data System (ADS)

Schumacher, R.; Schimpf, H.; Schiller, J.

2011-06-01

The most challenging problem of Automatic Target Recognition (ATR) is the extraction of robust and independent target features which describe the target unambiguously. These features have to be robust and invariant in different senses: in time, between aspect views (azimuth and elevation angle), between target motion (translation and rotation) and between different target variants. Especially for ground moving targets in military applications an irregular target motion is typical, so that a strong variation of the backscattered radar signal with azimuth and elevation angle makes the extraction of stable and robust features most difficult. For ATR based on High Range Resolution (HRR) profiles and / or Inverse Synthetic Aperture Radar (ISAR) images it is crucial that the reference dataset consists of stable and robust features, which, among others, will depend on the target aspect and depression angle amongst others. Here it is important to find an adequate data grid for an efficient data coverage in the reference dataset for ATR. In this paper the variability of the backscattered radar signals of target scattering centers is analyzed for different HRR profiles and ISAR images from measured turntable datasets of ground targets under controlled conditions. Especially the dependency of the features on the elevation angle is analyzed regarding to the ATR of large strip SAR data with a large range of depression angles by using available (I)SAR datasets as reference. In this work the robustness of these scattering centers is analyzed by extracting their amplitude, phase and position. Therefore turntable measurements under controlled conditions were performed targeting an artificial military reference object called STANDCAM. Measures referring to variability, similarity, robustness and separability regarding the scattering centers are defined. The dependency of the scattering behaviour with respect to azimuth and elevation variations is analyzed. Additionally generic types of features (geometrical, statistical), which can be derived especially from (I)SAR images, are applied to the ATR-task. Therefore subsequently the dependence of individual feature values as well as the feature statistics on aspect (i.e. azimuth and elevation) are presented. The Kolmogorov-Smirnov distance will be used to show how the feature statistics is influenced by varying elevation angles. Finally, confusion matrices are computed between the STANDCAM target at all eleven elevation angles. This helps to assess the robustness of ATR performance under the influence of aspect angle deviations between training set and test set.

Examination of the Lateral Attenuation of Aircraft Noise

NASA Technical Reports Server (NTRS)

Plotkin, Kenneth J.; Hobbs, Christopher M.; Bradley, Kevin A.; Shepherd, Kevin P. (Technical Monitor)

2000-01-01

Measurements of the lateral attenuation of noise from aircraft operations at Denver International Airport were made at distances up to 2000 feet and elevation angles up to 27 degrees. Attenuation Calculated from modem ground impedance theory agrees well with average measured attenuation. The large variability between measured and predicted levels observed at small elevation angles is demonstrated to be due to refraction by wind and temperature gradients.

Implant angulation: 2-year retrospective analysis on the influence of dental implant angle insertion on marginal bone resorption in maxillary and mandibular osseous onlay grafts.

PubMed

Ramaglia, Luca; Toti, Paolo; Sbordone, Carolina; Guidetti, Franco; Martuscelli, Ranieri; Sbordone, Ludovico

2015-05-01

The purpose of this study was to determine the existence of correlations between marginal peri-implant linear bone loss and the angulation of implants in maxillary and mandibular augmented areas over the course of a 2-year survey. Dependent variables described the sample of the present retrospective chart review. By using three-dimensional radiographs, input variables, describing the implant angulation (buccal-lingual angle [φ] and mesial-distal angle [θ]) were measured; outcome variables described survival rate and marginal bone resorption (MBR) around dental implants in autogenous grafts (10 maxillae and 14 mandibles). Pairwise comparisons and linear correlation coefficient were computed. The peri-implant MBR in maxillary buccal and palatal areas appeared less intensive in the presence of an increased angulation of an implant towards the palatal side. Minor MBR was recorded around mandibular dental implants positioned at a right angle and slightly angulated towards the mesial. Resorption in buccal areas may be less intensive as the angulation of placed implants increases towards the palatal area in the maxilla, whereas for the mandible, a greater inclination towards the lingual area could be negative. In the mandibular group, when the implant was slightly angulated in the direction of the distal area, bone resorption seemed to be more marked in the buccal area. In the planning of dental implant placement in reconstructed alveolar bone with autograft, the extremely unfavourable resorption at the buccal aspect should be considered; this marginal bone loss seemed to be very sensitive to the angulation of the dental implant.

Normative dimensions and symmetry of the lacrimal drainage system on dacryocystography: statistical analysis of morphometric characteristics.

PubMed

Horsburgh, A; Massoud, T F

2013-05-01

Asymmetric lacrimal flow occurs in females more than males. We hypothesised that the normal lacrimal drainage system (LDS) may show subtle left-right asymmetry in morphometry when imaged on dacryocystography (DCG). We retrospectively reviewed 60 normal bilateral LDSs.Images were analysed for 7 parameters: (1) combined length of either the superior or inferior canaliculus plus common canaliculus, (2) angle of insertion of common canaliculus into lacrimal sac (LS), (3, 4) length and width of the LS, (5) length of the naso lacrimal duct (NLD), and (6, 7) width of proximal and distal NLD. We tested the effect of independent variables (age, gender, and side) on each dependent variable (length, width, or angle) using regression analysis. We used a Studentt-test for independent samples to statistically compare bilateral LDSs. Patient median age was 62 years, and male:female ratio was 27:73. Mean dimensions and angles for all LDSs were: (1) 14.5 mm, (2) 57°,(3) 11.6 mm, (4) 2.1 mm, (5) 20.7 mm, (6) 1.4 mm, and (7) 1.8 mm. No independent variable affected variation in length, width, or angle. No significant difference emerged between dimensions of right and left LDSs in both sexes. A degree of affective lateralisation in the brain is known to result in lacrimal flow asymmetry after mood manipulation. We show that this is not reflected in LDS anatomy. Moreover, our detailed morphometric data can aid in therapeutic planning of LDS luminal procedures, especially when DCG images of one LDS are used as a road map for contralateral interventions.

Parametrization of a force field for metals complexed to biomacromolecules: applications to Fe(II), Cu(II) and Pb(II)

NASA Astrophysics Data System (ADS)

David, Laurent; Amara, Patricia; Field, Martin J.; Major, François

2002-08-01

Although techniques for the simulation of biomolecules, such as proteins and RNAs, have greatly advanced in the last decade, modeling complexes of biomolecules with metal ions remains problematic. Precise calculations can be done with quantum mechanical methods but these are prohibitive for systems the size of macromolecules. More qualitative modeling can be done with molecular mechanical potentials but the parametrization of force fields for metals is often difficult, particularly if the bonding between the metal and the groups in its coordination shell has significant covalent character. In this paper we present a method for deriving bond and bond-angle parameters for metal complexes from experimental bond and bond-angle distributions obtained from the Cambridge Structural Database. In conjunction with this method, we also introduce a non-standard energy term of gaussian form that allows us to obtain a stable description of the coordination about a metal center during a simulation. The method was evaluated on Fe(II)-porphyrin complexes, on simple Cu(II) ion complexes and a number of complexes of the Pb(II) ion.

Unsteady Aerodynamic Testing Using the Dynamic Plunge Pitch and Roll Model Mount

NASA Technical Reports Server (NTRS)

Lutze, Frederick H.; Fan, Yigang

1999-01-01

A final report on the DyPPiR tests that were run are presented. Essentially it consists of two parts, a description of the data reduction techniques and the results. The data reduction techniques include three methods that were considered: 1) signal processing of wind on - wind off data; 2) using wind on data in conjunction with accelerometer measurements; and 3) using a dynamic model of the sting to predict the sting oscillations and determining the aerodynamic inputs using an optimization process. After trying all three, we ended up using method 1, mainly because of its simplicity and our confidence in its accuracy. The results section consists of time history plots of the input variables (angle of attack, roll angle, and/or plunge position) and the corresponding time histories of the output variables, C(sub L), C(sub D), C(sub m), C(sub l), C(sub m), C(sub n). Also included are some phase plots of one or more of the output variable vs. an input variable. Typically of interest are pitch moment coefficient vs. angle of attack for an oscillatory motion where the hysteresis loops can be observed. These plots are useful to determine the "more interesting" cases. Samples of the data as it appears on the disk are presented at the end of the report. The last maneuver, a rolling pull up, is indicative of the unique capabilities of the DyPPiR, allowing combinations of motions to be exercised at the same time.

Crystal structure of (pyridine-κN)bis(quinolin-2-olato-κ2 N,O)copper(II) monohydrate

PubMed Central

Hawks, Benjamin; Yan, Jingjing; Basa, Prem; Burdette, Shawn

2015-01-01

The title complex, [Cu(C9H6NO)2(C5H4N)]·H2O, adopts a slightly distorted square-pyramidal geometry in which the axial pyridine ligand exhibits a long Cu—N bond of 2.305 (3) Å. The pyridine ligand forms dihedral angles of 79.5 (5) and 88.0 (1)° with the planes of the two quinolin-2-olate ligands, while the dihedral angle between the quinoline groups of 9.0 (3)° indicates near planarity. The water mol­ecule connects adjacent copper complexes through O—H⋯O hydrogen bonds to phenolate O atoms, forming a network inter­connecting all the complexes in the crystal lattice. PMID:25878845

Coordination and structure of Ca(II)-acetate complexes in aqueous solution studied by a combination of Raman and XAFS spectroscopies

NASA Astrophysics Data System (ADS)

Muñoz Noval, Álvaro; Nishio, Daisuke; Kuruma, Takuya; Hayakawa, Shinjiro

2018-06-01

The determination of the structure of Ca(II)-acetate in aqueous solution has been addressed by combining Raman and X-ray absorption fine structure spectroscopies. The pH-dependent speciation of the acetate/Ca(II) system has been studied observing modifications in specific Raman bands of the carboxyl group. The current results evidence the Ca(II)-acetate above acetate pKa forms a bidentate complex and presents a coordination 6, in which the Ca-O shell radius decrease of about 0.1 Å with respect the hydrated Ca2+ with coordination 8. The experimental results show the OCO angle of the carboxyl in the complex is close to 124°, being the OCaO angle about 60°.

Synthesis and crystal structure of the rhodium(I) cyclooctadiene complex with bis(3-tert-butylimidazol-2-ylidene)borate ligand

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, F.; Shao, K.-J.; Xiao, Y.-C.

2015-12-15

The rhodium(I) cyclooctadiene complex with the bis(3-tert-butylimidazol-2-ylidene)borate ligand [H{sub 2}B(Im{sup t}Bu){sup 2}]Rh(COD) C{sup 22}H{sup 36}BN{sup 4}Rh, has been prepared, and its crystal structure is determined by X-ray diffraction. Complex exhibits slightly distorted square planar configurations around the metal center, which is coordinated by the bidentate H{sup 2}B(Im{sup t}Bu){sub 2} and one cyclooctadiene group. The Rh–C{sub carbene} bond lengths are 2.043(4) and 2.074(4) Å, and the bond angle C–Rh1–C is 82.59°. The dihedral angle between two imidazol-2-ylidene rings is 67.30°.

Hyperon photoproduction in the nucleon resonance region

NASA Astrophysics Data System (ADS)

McNabb, J. W.; Schumacher, R. A.; Todor, L.; Adams, G.; Anciant, E.; Anghinolfi, M.; Asavapibhop, B.; Audit, G.; Auger, T.; Avakian, H.; Bagdasaryan, H.; Ball, J. P.; Barrow, S.; Battaglieri, M.; Beard, K.; Bektasoglu, M.; Bellis, M.; Berman, B. L.; Bianchi, N.; Biselli, A. S.; Boiarinov, S.; Bonner, B. E.; Bouchigny, S.; Bradford, R.; Branford, D.; Briscoe, W. J.; Brooks, W. K.; Burkert, V. D.; Butuceanu, C.; Calarco, J. R.; Carman, D. S.; Carnahan, B.; Cetina, C.; Ciciani, L.; Cole, P. L.; Coleman, A.; Cords, A. D.; Corvisiero, P.; Crabb, D.; Crannell, H.; Cummings, J. P.; de Sanctis, E.; Devita, R.; Degtyarenko, P. V.; Denizli, H.; Dennis, L.; Dharmawardane, K. V.; Dhuga, K. S.; Djalali, C.; Dodge, G. E.; Doughty, D.; Dragovitsch, P.; Dugger, M.; Dytman, S.; Eckhause, M.; Egiyan, H.; Egiyan, K. S.; Elouadrhiri, L.; Empl, A.; Eugenio, P.; Fatemi, R.; Feuerbach, R. J.; Ficenec, J.; Forest, T. A.; Funsten, H.; Gaff, S. J.; Gavalian, G.; Gilad, S.; Gilfoyle, G. P.; Giovanetti, K. L.; Girard, P.; Gordon, C. I.; Griffioen, K.; Guidal, M.; Guillo, M.; Guo, L.; Gyurjyan, V.; Hadjidakis, C.; Hakobyan, R.; Hardie, J.; Heddle, D.; Heimberg, P.; Hersman, F. W.; Hicks, K.; Hicks, R. S.; Holtrop, M.; Hu, J.; Hyde-Wright, C. E.; Ilieva, Y.; Ito, M. M.; Jenkins, D.; Joo, K.; Kelley, J. H.; Khandaker, M.; Kim, K. Y.; Kim, K.; Kim, W.; Klein, A.; Klein, F. J.; Klimenko, A. V.; Klusman, M.; Kossov, M.; Kramer, L. H.; Kuang, Y.; Kuhn, S. E.; Lachniet, J.; Laget, J. M.; Lawrence, D.; Li, Ji; Lukashin, K.; Manak, J. J.; Marchand, C.; McAleer, S.; McCarthy, J.; Mecking, B. A.; Mehrabyan, S.; Melone, J. J.; Mestayer, M. D.; Meyer, C. A.; Mikhailov, K.; Minehart, R.; Mirazita, M.; Miskimen, R.; Morand, L.; Morrow, S. A.; Muccifora, V.; Mueller, J.; Mutchler, G. S.; Napolitano, J.; Nasseripour, R.; Nelson, S. O.; Niccolai, S.; Niculescu, G.; Niculescu, I.; Niczyporuk, B. B.; Niyazov, R. A.; Nozar, M.; O'Brien, J. T.; O'Rielly, G. V.; Osipenko, M.; Park, K.; Pasyuk, E.; Peterson, G.; Philips, S. A.; Pivnyuk, N.; Pocanic, D.; Pogorelko, O.; Polli, E.; Pozdniakov, S.; Preedom, B. M.; Price, J. W.; Prok, Y.; Protopopescu, D.; Qin, L. M.; Quinn, B. P.; Raue, B. A.; Riccardi, G.; Ricco, G.; Ripani, M.; Ritchie, B. G.; Ronchetti, F.; Rossi, P.; Rowntree, D.; Rubin, P. D.; Sabatié, F.; Sabourov, K.; Salgado, C.; Santoro, J. P.; Sapunenko, V.; Serov, V. S.; Shafi, A.; Sharabian, Y. G.; Shaw, J.; Simionatto, S.; Skabelin, A. V.; Smith, E. S.; Smith, L. C.; Sober, D. I.; Spraker, M.; Stavinsky, A.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Taiuti, M.; Taylor, S.; Tedeschi, D. J.; Thoma, U.; Thompson, R.; Tur, C.; Ungaro, M.; Vineyard, M. F.; Vlassov, A. V.; Wang, K.; Weinstein, L. B.; Weisberg, A.; Weller, H.; Weygand, D. P.; Whisnant, C. S.; Wolin, E.; Wood, M. H.; Yegneswaran, A.; Yun, J.; Zhang, B.; Zhao, J.; Zhou, Z.

2004-04-01

High-statistics cross sections and recoil polarizations for the reactions γ+p→ K+ +Λ and γ+p→ K+ + Σ0 have been measured at CLAS for center-of-mass energies between 1.6 and 2.3 GeV . In the K+ Λ channel we confirm a resonance-like structure near W=1.9 GeV at backward kaon angles. Our data show more complex s - and u - channel behavior than previously seen, since structure is also present at forward angles, but not at central angles. The position and width change with angle, indicating that more than one resonance is playing a role. Large positive Λ polarization at backward angles, which is also energy dependent, is consistent with sizable s - or u -channel contributions. Presently available model calculations cannot explain these aspects of the data.

Effects of Sweep Angle on the Boundary-Layer Stability Characteristics of an Untapered Wing at Low Speeds

NASA Technical Reports Server (NTRS)

Boltz, Frederick W.; Kenyon, George C.; Allen, Clyde Q.

1960-01-01

An investigation was conducted in the Ames 12-Foot Low-Turbulence Pressure Tunnel to determine the effects of sweep on the boundary-layer stability characteristics of an untapered variable-sweep wing having an NACA 64(2)A015 section normal to the leading edge. Pressure distribution and transition were measured on the wing at low speeds at sweep angles of 0, 10, 20, 30, 40, and 50 deg. and at angles of attack from -3 to 3 deg. The investigation also included flow-visualization studies on the surface at sweep angles from 0 to 50 deg. and total pressure surveys in the boundary layer at a sweep angle of 30 deg. for angles of attack from -12 to 0 deg. It was found that sweep caused premature transition on the wing under certain conditions. This effect resulted from the formation of vortices in the boundary layer when a critical combination of sweep angle, pressure gradient, and stream Reynolds number was attained. A useful parameter in indicating the combined effect of these flow variables on vortex formation and on beginning transition is the crossflow Reynolds number. The critical values of crossflow Reynolds number for vortex formation found in this investigation range from about 135 to 190 and are in good agreement with those reported in previous investigations. The values of crossflow Reynolds number for beginning transitions were found to be between 190 and 260. For each condition (i.e., development of vortices and initiation of transition at a given location) the lower values in the specified ranges were obtained with a light coating of flow-visualization material on the surface. A method is presented for the rapid computation of crossflow Reynolds number on any swept surface for which the pressure distribution is known. From calculations based on this method, it was found that the maximum values of crossflow Reynolds number are attained under conditions of a strong pressure gradient and at a sweep angle of about 50 deg. Due to the primary dependence on pressure gradient, effects of sweep in causing premature transition are generally first encountered on the lower surfaces of wings operating at positive angles of attack.

What is an Oceanic Core Complex?

NASA Astrophysics Data System (ADS)

Schroeder, T.; Cheadle, M. J.

2007-12-01

The Mid-Atlantic Ridge (MAR) 75km north and south of the 15-20 Fracture Zone (FZ) has produced upper oceanic lithosphere composed dominantly of mantle peridotite with gabbro intrusions. In the absence of diapirism, mantle peridotite can only be exposed on the seafloor by extensional faulting, thus the sea floor geology and bathymetry provide widespread evidence for extensive low-angle faulting. However, only 3% of the seafloor in this region has the domal morphology characteristic of features that have been termed oceanic core complexes; suggesting that other processes, in addition to low-angle faulting, are responsible for the generation of domal core complexes. Most low-angle faults near the 15-20 FZ form gently dipping (10-15°), 10-15km-wide dip slopes on the flanks of 2000m relief bathymetric ridges that are up to 15-40km long (parallel to the MAR). Core recovered from ODP Leg 209 drill holes in these ridges is dominantly peridotite with small (<50m thick) gabbro intrusions. The peridotite is cut by a very high density of brittle faults dipping at both steep and gentle angles. Several holes also contain long-lived shear zones/faults in their upper reaches in which strain was localized at granulite facies, indicated by mylonitic olivine and cpx, and remained active during cooling to sub-greenschist grade, indicated by cross-cutting of progressively lower-grade syn-deformation mineral assemblages. These observations suggest that seafloor spreading is largely accommodated here by slip on low-angle faults, and that these faults are correctly termed detachment faults. Holes drilled into a domal oceanic core complex north of the 15-20 FZ during Leg 209 (ODP Site 1275) recovered dominantly gabbro and not mantle peridotite. This hole is cut by significantly fewer brittle and ductile faults than the peridotite drilled at the non-core-complex detachment fault sites. The detachment fault in the upper reaches (50m) of Site 1275 was localized at temperatures near feldspar's ductile-to-brittle transition, indicated by cataclasis with minor crystal plastic flow in plagioclase, and a lack of pervasive pure-ductile deformation. Amphibole-plagioclase thermometry in the fault yields equilibrium temperatures from 600-650°C, compared to equilibrium temperatures of 750-850°C for the gabbro outside the fault. The presence of talc- chlorite schists and cataclasites cutting the higher-temperature deformation textures indicate fault activity down- temperature from amphibolite through greenschist facies. This core-complex-bounding fault contrasts with the fault that bounds the Atlantis Bank Core Complex on the Southwest Indian Ridge (SWIR). There, the fault is 100m thick and strain was initially localized at granulite grade (>800°C) (Mehl & Hirth, 2007); significantly hotter than the Site 1275 fault. Therefore, the formation of core-complex morphology does not seem to depend on the initial faulting conditions. Both oceanic core complexes that have been drilled besides Site 1275, Atlantis Massif at 30°N (IODP Hole 1309D) on the MAR and Atlantis Bank on the SWIR (ODP Hole 735B), are also comprised dominantly of gabbro. This suggests that magma supply may be an essential requirement for core complex formation and raises the question whether all domal oceanic core complexes are cored by gabbro? We also ask whether the term 'oceanic core complex' should be restricted to these domal features and not applied to detachment-bound, non- domal, peridotite-cored ridges; or if these should be considered two sub-classes of oceanic core complexes.

Prediction of projectile ricochet behavior after water impact.

PubMed

Baillargeon, Yves; Bergeron, Guy

2012-11-01

Although not very common, forensic investigation related to projectile ricochet on water can be required when undesirable collateral damage occurs. Predicting the ricochet behavior of a projectile is challenging owing to numerous parameters involved: impact velocity, incident angle, projectile stability, angular velocity, etc. Ricochet characteristics of different projectiles (K50 BMG, 0.5-cal Ball M2, 0.5-cal AP-T C44, 7.62-mm Ball C21, and 5.56-mm Ball C77) were studied in a pool. The results are presented to assess projectile velocity after ricochet, ricochet angle, and projectile azimuth angle based on impact velocity or incident angle for each projectile type. The azimuth ranges show the highest variability at low postricochet velocity. The critical ricochet angles were ranging from 15 to 30°. The average ricochet angles for all projectiles were pretty close for all projectiles at 2.5 and 10° incident angles for the range of velocities studied. © 2012 Her Majesty the Queen in Right of Canada 2012. Reproduced with the permission of the Minister of the Department of National Defence.

Measurement of Aerodynamic Forces for Various Mean Angles of Attack on an Airfoil Oscillating in Pitch and on Two Finite-span Wings Oscillating in Bending with Emphasis on Damping in the Stall

NASA Technical Reports Server (NTRS)

Rainey, A Gerald

1957-01-01

The oscillating air forces on a two-dimensional wing oscillating in pitch about the midchord have been measured at various mean angles of attack and at Mach numbers of 0.35 and 0.7. The magnitudes of normal-force and pitching-moment coefficients were much higher at high angles of attack than at low angles of attack for some conditions. Large regions of negative damping in pitch were found, and it was shown that the effect of increasing the Mach number 0.35 to 0.7 was to decrease the initial angle of attack at which negative damping occurred. Measurements of the aerodynamic damping of a 10-percent-thick and of a 3-percent-thick finite-span wing oscillating in the first bending mode indicate no regions of negative damping for this type of motion over the range of variables covered. The damping measured at high angles of attack was generally larger than that at low angles of attack. (author)

The effect of display movement angle, indicator type and display location on control/display stereotype strength.

PubMed

Hoffmann, Errol R; Chan, Alan H S

2017-08-01

Much research on stereotype strength relating display and control movements for displays moving in the vertical or horizontal directions has been reported. Here we report effects of display movement angle, where the display moves at angles (relative to the vertical) of between 0° and 180°. The experiment used six different controls, four display locations relative to the operator and three types of indicator. Indicator types were included because of the strong effects of the 'scale-side principle' that are variable with display angle. A directional indicator had higher stereotype strength than a neutral indicator, and showed an apparent reversal in control/display stereotype direction beyond an angle of 90°. However, with a neutral indicator this control reversal was not present. Practitioner Summary: The effects of display moving at angles other than the four cardinal directions, types of control, location of display and types of indicator are investigated. Indicator types (directional and neutral) have an effect on stereotype strength and may cause an apparent control reversal with change of display movement angle.

Rapid Communication: Effect of machine, anatomical location, and replication on instrumental color of boneless pork loins.

PubMed

Barkley, K E; Fields, B; Dilger, A C; Boler, D D

2018-06-07

The objective was to determine the effect of machine, anatomical location and replication (multiple readings) on instrumental color and to characterize the amount of variation each factor contributed to overall color. Instrumental color was measured 3 times on the anterior and 3 times on the posterior end of 250 pork loins with 2 different Minolta CR-400 Chroma meter devices. Each Minolta was programed to use a D65 illuminant, 2º observer with an 8 mm aperture, and calibrated with white tiles specific to each machine. Therefore, a total of 12 instrumental color measurements were collected on each loin. The VARCOMP procedure in SAS was used to estimate the proportion of variation contributed by each factor to CIE L*, a*, b*, chroma and hue. Based on previous research, the average untrained consumer is able to distinguish between 3-L* units, 0.4-a* units, and 0.9-hue angle units. Loins evaluated with machine 1 were 0.71 L* units darker (P < 0.01), 1.09 b* units more yellow (P < 0.01), 0.47 chroma units more saturated (P < 0.01), and had a hue angle 5.12 units greater (P < 0.01) than when evaluated with machine 2 but did not differ (P = 0.24) in redness. The anterior portion of the loin was lighter, less red, more yellow, more saturated and had a greater hue angle than the posterior end (P < 0.01). All color trait values decreased (P < 0.01) as replication number increased. Inherent color differences among loins contributed the greatest proportion of variability for lightness (58%), redness (57%), yellowness (70%), saturation (70%) and hue angle (49%). Machine contributed 1% variability to lightness 3% to saturation, 23% to yellowness and 31% to hue angle (31%) but did not contribute to variability for redness. Anatomical location contributed 41% to lightness, 43% to redness, 7% to yellowness, 27% to saturation and 31% to hue angle. Replication did not contribute to total variation for any color traits, even though it did differ among measurements. Overall, there were differences in instrumental color values between the two machines tested but those differences were likely less than the threshold for detection by a consumer. Even so, inherent color differences between loins were a greater contributor to total variability than the differences between the 2 machines. Therefore, it is more important to define the location of measurements than replication or machine when using a Minolta CR-400 when performing color evaluations, assuming the settings are the same.

Inter- and intraobserver reliability assessment of the axial trunk rotation: manual versus smartphone-aided measurement tools.

PubMed

Qiao, Jun; Xu, Leilei; Zhu, Zezhang; Zhu, Feng; Liu, Zhen; Qian, Bangping; Qiu, Yong

2014-10-11

Scoliogauge, has been developed for the measurement of ATR on iPhone smartphones. This study was to evaluate the reliability for the smartphone-aided ATR measurement method and to compare its reliability with that of the manual method. Sixty-four AIS patients with single thoracic or lumbar curve participated in this study. Of these patients, thirty-two patients had main thoracic scoliosis while other thirty-two had main thoracolumbar/lumbar scoliosis. Two spine surgeons performed the measurements with Scoliometer and Scoliogauge. The Scoliogauge measurements were conducted on an iPhone 4 smartphone. The intraclass correlation coefficient (ICC) 2-way mixed model on absolute agreement was used to analyze the reliability categorized according to regions: thoracic or lumbar, and Cobb angles: <20 degrees and >40 degrees. ICC < 0.40 is considered as poor, 0.40-0.59 as fair, 0.60-0.74 as good, and 0.75-1.00 as excellent. The overall intraobserver variability was 0.954 and the overall interobserver variability was 0.943 for the scoliometer set, whereas the intraobserver variability was 0.965 and interobserver variability was 0.964 for the scoliogauge set. Both the intraobserver and interobserver ICCs reached the excellent value in the 2 sets for both observers. The mean Cobb angle of thoracic curves in patients with main thoracic scoliosis was similar to that of lumbar curves in those with main thoracolumbar/lumbar scoliosis (35.7 degrees vs. 36.1 degrees). The intraobserver and interobserver reliability was similar between two groups (thoracic vs. lumbar) in the 2 sets. There were 21 patients having Cobb angles < 20 degrees, while 20 patients >40 degrees. The intraobserver and interobserver reliability was better in severe curve(>40 degrees) group. Smartphone-aided measurement for ATR showed excellent reliability, and the reliability of measurement with either scoliometer or scoliogauge could be influenced by Cobb angle that reliability was better for curves with larger Cobb angles.

Analysis of polarization radar returns from ice clouds

NASA Astrophysics Data System (ADS)

Battaglia, A.; Sturniolo, O.; Prodi, F.

Using a modified T-matrix code, some polarimetric single-scattering radar parameters ( Zh,v, LDR h,v, ρhv, ZDR and δhv) from populations of ice crystals in ice phase at 94 GHz, modeled with axisymmetric prolate and oblate spheroidal shapes for a Γ-size distribution with different α parameter ( α=0, 1, 2) and characteristic dimension Lm varying from 0.1 to 1.8 mm, have been computed. Some of the results for different radar elevation angles and different orientation distribution for fixed water content are shown. Deeper analysis has been carried out for pure extensive radar polarimetric variables; all of them are strongly dependent on the shapes (characterised by the aspect ratio), the canting angle and the radar elevation angle. Quantities like ZDR or δhv at side incidence or LDR h and ρhv at vertical incidence can be used to investigate the preferred orientation of the particles and, in some cases, their habits. We analyze scatterplots using couples of pure extensive variables. The scatterplots with the most evident clustering properties for the different habits seem to be those in the ( ZDR [ χ=0°], δhv [ χ=0°]), in the ( ZDR [ χ=0°], LDR h [ χ=90°]) and in the ( ZDR [ χ=0°], ρhv [ χ=90°]) plane. Among these, the most appealing one seems to be that involving ZDR and ρhv variables. To avoid the problem of having simultaneous measurements with a side and a vertical-looking radar, we believe that measurements of these two extensive variables using a radar with an elevation angle around 45° can be an effective instrument to identify different habits. In particular, this general idea can be useful for future space-borne polarimetric radars involved in the studies of high ice clouds. It is also believed that these results can be used in next challenge of developing probabilistic and expert methods for identifying hydrometeor types by W-band radars.

A descriptive study of step alignment and foot positioning relative to the tee by professional rugby union goal-kickers.

PubMed

Cockcroft, John; Van Den Heever, Dawie

2016-01-01

This study describes foot positioning during the final two steps of the approach to the ball amongst professional rugby goal-kickers. A 3D optical motion capture system was used to test 15 goal-kickers performing 10 goal-kicks. The distance and direction of each step, as well as individual foot contact positions relative to the tee, were measured. The intra- and inter-subject variability was calculated as well as the correlation (Pearson) between the measurements and participant anthropometrics. Inter-subject variability for the final foot position was lowest (placed 0.03 ± 0.07 m behind and 0.33 ± 0.03 m lateral to the tee) and highest for the penultimate step distance (0.666 ± 0.149 m), performed at an angle of 36.1 ± 8.5° external to the final step. The final step length was 1.523 ± 0.124 m, executed at an external angle of 35.5 ± 7.4° to the target line. The intra-subject variability was very low; distances and angles for the 10 kicks varied per participant by 1.6-3.1 cm and 0.7-1.6°, respectively. The results show that even though the participants had variability in their run-up to the tee, final foot position next to the tee was very similar and consistent. Furthermore, the inter- and intra-subject variability could not be attributed to differences in anthropometry. These findings may be useful as normative reference data for coaching, although further work is required to understand the role of other factors such as approach speed and body alignment.

Running Mechanics and Variability with Aging.

PubMed

Silvernail, Julia Freedman; Boyer, Katherine; Rohr, Eric; Brüggemann, Gert-Peter; Hamill, Joseph

2015-10-01

As the elderly population in the United States continues to grow, issues related to maintenance of health become increasingly important. Physical activity has positive benefits for healthy aging. Running, a popular form of exercise, is associated with the risk of developing injury, especially in older runners. Initial differences between older and younger runners have been observed, but these were observed without consideration of other differences between groups, such as running mileage. This study aims to compare running mechanics and lower-extremity coordination variability in matched groups of healthy younger and healthy older runners. Three-dimensional kinetics and kinematics were collected while 14 older adults (45-65 yr) and younger adults (18-35 yr) ran overground at 3.5 m·s. Knee, ankle, and hip joint angles and moments were determined. Discrete measures at foot strike (maximum and minimum) were determined and compared between groups. Segment angles during stance were utilized to calculate segment coordination variability between pelvis and thigh, thigh and shank, and shank and foot, using a modified vector coding technique. Knee and ankle joint angles were similar between groups (P > 0.05). Older runners had greater hip range of motion (P = 0.01) and peak hip flexion (P = 0.001) at a more extended hip position than younger runners. Older runners had smaller ankle plantarflexion moment (P = 0.04) and hip rotational moment (P = 0.005) than younger runners. There were no between-group differences in any of the variability measures (P > 0.05). Runners appear to maintain movement patterns and variability during running with increasing age, indicating that running itself may be contributing to maintenance of health among older runners in the current study.

Shape of Thyroid Cartilage Influences Outcome of Montgomery Medialization Thyroplasty: A Gender Issue.

PubMed

Desuter, Gauthier; Henrard, Sylvie; Van Lith-Bijl, Julie T; Amory, Avigaëlle; Duprez, Thierry; van Benthem, Peter Paul; Sjögren, Elisabeth

2017-03-01

This study aimed to determine whether the shape of the thyroid cartilage and gender influence voice outcomes after a Montgomery thyroplasty implant system (MTIS). A retrospective cohort study was performed on 20 consecutive patients who underwent MTIS. Voice outcome variables were the relative decrease in Voice Handicap Index (%) and the absolute increase in maximum phonation time (MPT) (in seconds). Material variables were the angle between the thyroid cartilage laminae (α-angle), the size of the prosthesis, and a combination of both (the α-ratio). Continuous variables were analyzed using medians and were compared between groups using the Mann-Whitney U test. Factors associated with the outcome variables were assessed by multivariable linear regression. A Pearson coefficient was calculated between material variables. The absolute increase in MPT between the pre- and postoperative period was significantly different between men and women, with a median absolute increase of 11.0 seconds for men and of 1.3 seconds for women (P < 0.001). A strong inverse correlation between the α-ratio and the absolute increase in MPT is observed in all patients, with a Pearson correlation coefficient R = -0.769 (P < 0.001). No factors were significantly associated with the relative Voice Handicap Index decrease in univariable or multivariable analyses. A better Pearson coefficient between the α-angle and the prosthesis size was found for females (0.8 vs 0.71). The MTIS is a good thyroplasty modality for male patients, but inadequate design of MTIS female implants leads to poor MPT outcomes. This represents a gender issue that needs to be further studied and eventually tackled. Copyright © 2017 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Elbow joint position sense after neuromuscular training with handheld vibration.

PubMed

Tripp, Brady L; Faust, Donald; Jacobs, Patrick

2009-01-01

Clinicians use neuromuscular control exercises to enhance joint position sense (JPS); however, because standardizing such exercises is difficult, validations of their use are limited. To evaluate the acute effects of a neuromuscular training exercise with a handheld vibrating dumbbell on elbow JPS acuity. Crossover study. University athletic training research laboratory. Thirty-one healthy, college-aged volunteers (16 men, 15 women, age = 23 + or - 3 years, height = 173 + or - 8 cm, mass = 76 + or - 14 kg). We measured and trained elbow JPS using an electromagnetic tracking device that provided auditory and visual biofeedback. For JPS testing, participants held a dumbbell and actively identified the target elbow flexion angle (90 degrees ) using the software-generated biofeedback, followed by 3 repositioning trials without feedback. Each neuromuscular training protocol included 3 exercises during which participants held a 2.55-kg dumbbell vibrating at 15, 5, or 0 Hz and used software-generated biofeedback to locate and maintain the target elbow flexion angle for 15 seconds. We calculated absolute (accuracy) and variable (variability) errors using the differences between target and reproduced angles. Training protocols using 15-Hz vibration enhanced accuracy and decreased variability of elbow JPS (P < or = .005), whereas 5-Hz vibration did not affect accuracy (F(1,61) = 2.625, P = .100) but did decrease variability (F(1,61) = 7.250, P = .009). The control condition and 0-Hz training protocol had no effect on accuracy or variability (P > or = .200). Our results suggest these neuromuscular control exercises, which included low-magnitude, low-frequency handheld vibration, may enhance elbow JPS. Future researchers should examine vibration of various durations and frequencies, should include injured participants and functional multijoint and multiplanar measures, and should examine long-term effects of training protocols on JPS and injury.

Adaptive pitch control for variable speed wind turbines

DOEpatents

Johnson, Kathryn E [Boulder, CO; Fingersh, Lee Jay [Westminster, CO

2012-05-08

An adaptive method for adjusting blade pitch angle, and controllers implementing such a method, for achieving higher power coefficients. Average power coefficients are determined for first and second periods of operation for the wind turbine. When the average power coefficient for the second time period is larger than for the first, a pitch increment, which may be generated based on the power coefficients, is added (or the sign is retained) to the nominal pitch angle value for the wind turbine. When the average power coefficient for the second time period is less than for the first, the pitch increment is subtracted (or the sign is changed). A control signal is generated based on the adapted pitch angle value and sent to blade pitch actuators that act to change the pitch angle of the wind turbine to the new or modified pitch angle setting, and this process is iteratively performed.

Uncertainty of Videogrammetric Techniques used for Aerodynamic Testing

NASA Technical Reports Server (NTRS)

Burner, A. W.; Liu, Tianshu; DeLoach, Richard

2002-01-01

The uncertainty of videogrammetric techniques used for the measurement of static aeroelastic wind tunnel model deformation and wind tunnel model pitch angle is discussed. Sensitivity analyses and geometrical considerations of uncertainty are augmented by analyses of experimental data in which videogrammetric angle measurements were taken simultaneously with precision servo accelerometers corrected for dynamics. An analysis of variance (ANOVA) to examine error dependence on angle of attack, sensor used (inertial or optical). and on tunnel state variables such as Mach number is presented. Experimental comparisons with a high-accuracy indexing table are presented. Small roll angles are found to introduce a zero-shift in the measured angles. It is shown experimentally that. provided the proper constraints necessary for a solution are met, a single- camera solution can he comparable to a 2-camera intersection result. The relative immunity of optical techniques to dynamics is illustrated.

Nanopatterning of swinging substrates by ion-beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoon, Sun Mi; Kim, J.-S., E-mail: jskim@sm.ac.kr

Graphite substrates are azimuthally swung during ion-beam sputtering (IBS) at a polar angle θ = 78° from the surface normal. The swinging of the substrate not only causes quasi-two-dimensional mass transport but also makes various sputter effects from the different incident angles to work together. Through variation of the swing angle, both the transport and sputtering effects synergistically produce a series of salient patterns, such as asymmetric wall-like structures, which can grow to several tens of nanometers and exhibit a re-entrant orientational change with the increased swing angle. Thus, the present work demonstrates that dynamic variables such as the swing angle, whichmore » have been little utilized, offer an additional parameter space that can be exploited to diversify the sputtered patterns, thereby expanding the applicability of an IBS as well as the comprehension of the IBS nano patterning mechanism.« less

Method for controlling a vehicle with two or more independently steered wheels

DOEpatents

Reister, D.B.; Unseren, M.A.

1995-03-28

A method is described for independently controlling each steerable drive wheel of a vehicle with two or more such wheels. An instantaneous center of rotation target and a tangential velocity target are inputs to a wheel target system which sends the velocity target and a steering angle target for each drive wheel to a pseudo-velocity target system. The pseudo-velocity target system determines a pseudo-velocity target which is compared to a current pseudo-velocity to determine a pseudo-velocity error. The steering angle targets and the steering angles are inputs to a steering angle control system which outputs to the steering angle encoders, which measure the steering angles. The pseudo-velocity error, the rate of change of the pseudo-velocity error, and the wheel slip between each pair of drive wheels are used to calculate intermediate control variables which, along with the steering angle targets are used to calculate the torque to be applied at each wheel. The current distance traveled for each wheel is then calculated. The current wheel velocities and steering angle targets are used to calculate the cumulative and instantaneous wheel slip and the current pseudo-velocity. 6 figures.

Servo Controlled Variable Pressure Modification to Space Shuttle Hydraulic Pump

NASA Technical Reports Server (NTRS)

Kouns, H. H.

1983-01-01

Engineering drawings show modifications made to the constant pressure control of the model AP27V-7 hydraulic pump to an electrically controlled variable pressure setting compensator. A hanger position indicator was included for continuously monitoring hanger angle. A simplex servo driver was furnished for controlling the pressure setting servovalve. Calibration of the rotary variable displacement transducer is described as well as pump performance and response characteristics.

A Survey of Phase Variable Candidates of Human Locomotion

PubMed Central

Villarreal, Dario J.; Gregg, Robert D.

2014-01-01

Studies show that the human nervous system is able to parameterize gait cycle phase using sensory feedback. In the field of bipedal robots, the concept of a phase variable has been successfully used to mimic this behavior by parameterizing the gait cycle in a time-independent manner. This approach has been applied to control a powered transfemoral prosthetic leg, but the proposed phase variable was limited to the stance period of the prosthesis only. In order to achieve a more robust controller, we attempt to find a new phase variable that fully parameterizes the gait cycle of a prosthetic leg. The angle with respect to a global reference frame at the hip is able to monotonically parameterize both the stance and swing periods of the gait cycle. This survey looks at multiple phase variable candidates involving the hip angle with respect to a global reference frame across multiple tasks including level-ground walking, running, and stair negotiation. In particular, we propose a novel phase variable candidate that monotonically parameterizes the whole gait cycle across all tasks, and does so particularly well across level-ground walking. In addition to furthering the design of robust robotic prosthetic leg controllers, this survey could help neuroscientists and physicians study human locomotion across tasks from a time-independent perspective. PMID:25570873

Analysis of axial spatial resolution in a variable resolution x-ray cone beam CT (VRX-CBCT) system

NASA Astrophysics Data System (ADS)

Dahi, Bahram; Keyes, Gary S.; Rendon, David A.; DiBianca, Frank A.

2008-03-01

The Variable Resolution X-ray (VRX) technique has been successfully used in a Cone-Beam CT (CBCT) system to increase the spatial resolution of CT images in the transverse plane. This was achieved by tilting the Flat Panel Detector (FPD) to smaller vrx y angles in a VRX Cone Beam CT (VRX-CBCT) system. In this paper, the effect on the axial spatial resolution of CT images created by the VRX-CBCT system is examined at different vrx x angles, where vrx x is the tilting angle of the FPD about its x-axis. An amorphous silicon FPD with a CsI scintillator is coupled with a micro-focus x-ray tube to form a CBCT. The FPD is installed on a rotating frame that allows rotation of up to 90° about x and y axes of the FPD. There is no rotation about the z-axis (i.e. normal to the imaging surface). Tilting the FPD about its x-axis (i.e. decreasing the vrx x angle) reduces both the width of the line-spread function and the sampling distance by a factor of sin vrx x, thereby increasing the theoretical detector pre-sampling spatial resolution proportionately. This results in thinner CT slices that in turn help increase the axial spatial resolution of the CT images. An in-house phantom is used to measure the MTF of the reconstructed CT images at different vrx x angles.

Angular photogrammetric analysis of the soft tissue profile in 12-year-old southern Chinese.

PubMed

Leung, Cindi Sy; Yang, Yanqi; Wong, Ricky Wk; Hägg, Urban; Lo, John; McGrath, Colman

2014-12-24

To quantify average angular measurements that define the soft tissue profiles of 12-year-old southern Chinese and to determine gender differences. A random population sample of 514 12-year-old children was recruited (about 10% of a Hong Kong Chinese birth cohort). Photographs were taken in natural head posture and 12 soft tissue landmarks were located on the photos to measure 12 angular measurements using ImageJ (V1.45s) for Windows. Approximately 10% of photographs were reanalyzed and method error was calculated. Angular norm values for the 12 parameters were determined and gender differences were assessed using 2 sample T-test with 95% confidence interval. The response rate was 54.1% (278/514). Norm values for the 12 angular measurements were generated. The greatest variability was found for the nasolabial (Cm-Sn-Ls) and labiomental (Li-Sm-Pg) angles. Gender differences were found in 4 angular parameters: vertical nasal angle (N-Prn/TV) (p < 0.05), cervicomental angle (G-Pg/C-Me) (p < 0.001), facial convexity angle (G-Sn-Pg) (p < 0.01) and total facial convexity angle (G-Prn-Pg)(p < 0.01). Norm values for 12 angular measurements among 12-year-old southern Chinese children were provided and some variability noted. Gender differences were apparent in several angular measurements. This study has implications in developing norm values for southern Chinese and for comparison with other ethnic groups.

Photophysical Properties of Pt(II) Polypyridines with Five- versus Six-Membered Chelate Rings: Trade-Offs in Angle Strain.

PubMed

Natoli, Sean N; Hight, Lauren M; Zeller, Matthias; McMillin, David R

2018-06-04

This report describes the synthesis and characterization of a series of eight [Pt(NNN)X] + complexes where the tridentate NNN ligand is (2,2'-bipyrid-6-yl)(pyrid-2-yl)sulfide (btp) or methyl(2,2'-bipyrid-6-yl)(pyrid-2-yl)amine (bmap) and X is OMe, Cl, phenylethynyl (C 2 Ph), or cyclohexylethynyl (C 2 Cy). The expectation was that inserting a heteroatom into the backbone of 2,2':6',2″-terpyridine (trpy) would expand the overall intraligand bite angle, introduce ILCT character into the excited states, and improve the photophysical properties. Crystal structures of [Pt(bmap)C 2 Ph] + and [Pt(btp)Cl] + reveal that atom insertion into the trpy backbone successfully expands the bite angle of the ligand by 8-10°. However, the impact on the photophysics is minimal. Indeed, of the eight systems investigated, only the [Pt(bmap)C 2 Ph] + and [Pt(btp)C 2 Ph] + complexes display appreciable emission in fluid solution, and they exhibit shorter emission lifetimes than [Pt(trpy)C 2 Ph] + . One reason is that the bond angle preferences of platinum and the inserted heteroatom induce the six-membered rings to deviate from planarity and adopt a boat-like conformation, impairing charge delocalization within the ligand. In addition, angle strain induces the donor atoms about platinum to assume a pseudotetrahedral arrangement, which offsets any benefit due to the increase in overall bite angle by promoting deactivation via d-d excited states. The results reveal that, in order to improve the luminescence of a [Pt(NNN)X] + system, one must take care to avoid trading one kind of angle strain for another.

An Efficient Adaptive Angle-Doppler Compensation Approach for Non-Sidelooking Airborne Radar STAP

PubMed Central

Shen, Mingwei; Yu, Jia; Wu, Di; Zhu, Daiyin

2015-01-01

In this study, the effects of non-sidelooking airborne radar clutter dispersion on space-time adaptive processing (STAP) is considered, and an efficient adaptive angle-Doppler compensation (EAADC) approach is proposed to improve the clutter suppression performance. In order to reduce the computational complexity, the reduced-dimension sparse reconstruction (RDSR) technique is introduced into the angle-Doppler spectrum estimation to extract the required parameters for compensating the clutter spectral center misalignment. Simulation results to demonstrate the effectiveness of the proposed algorithm are presented. PMID:26053755

From Fractal Trees to Deltaic Networks

NASA Astrophysics Data System (ADS)

Cazanacli, D.; Wolinsky, M. A.; Sylvester, Z.; Cantelli, A.; Paola, C.

2013-12-01

Geometric networks that capture many aspects of natural deltas can be constructed from simple concepts from graph theory and normal probability distributions. Fractal trees with symmetrical geometries are the result of replicating two simple geometric elements, line segments whose lengths decrease and bifurcation angles that are commonly held constant. Branches could also have a thickness, which in the case of natural distributary systems is the equivalent of channel width. In river- or wave-dominated natural deltas, the channel width is a function of discharge. When normal variations around the mean values for length, bifurcating angles, and discharge are applied, along with either pruning of 'clashing' branches or merging (equivalent to channel confluence), fractal trees start resembling natural deltaic networks, except that the resulting channels are unnaturally straight. Introducing a bifurcation probability fewer, naturally curved channels are obtained. If there is no bifurcation, the direction of each new segment depends on the direction the previous segment upstream (correlated random walk) and, to a lesser extent, on a general direction of growth (directional bias). When bifurcation occurs, the resulting two directions also depend on the bifurcation angle and the discharge split proportions, with the dominant branch following the direction of the upstream parent channel closely. The bifurcation probability controls the channel density and, in conjunction with the variability of the directional angles, the overall curvature of the channels. The growth of the network in effect is associated with net delta progradation. The overall shape and shape evolution of the delta depend mainly on the bifurcation angle average size and angle variability coupled with the degree of dominant direction dependency (bias). The proposed algorithm demonstrates how, based on only a few simple rules, a wide variety of channel networks resembling natural deltas, can be replicated. Network Example

The Effects of Bicycle Frame Geometry on Muscle Activation and Power During a Wingate Anaerobic Test

PubMed Central

Ricard, Mark D.; Hills-Meyer, Patrick; Miller, Michael G.; Michael, Timothy J.

2006-01-01

The purpose of this study was to compare the effects of bicycle seat tube angles (STA) of (72° and 82°) on power production and EMG of the vastus laeralis (VL), vastus medialis (VM), semimembranous (SM), biceps femoris (BF) during a Wingate test (WAT). Twelve experienced cyclists performed a WAT at each STA. Repeated measures ANOVA was used to identify differences in muscular activation by STA. EMG variables were normalized to isometric maximum voluntary contraction (MVC). Paired t-tests were used to test the effects of STA on: peak power, average power, minimum power and percent power drop. Results indicated BF activation was significantly lower at STA 82° (482.9 ± 166.6 %MVC·s) compared to STA 72° (712.6 ± 265.6 %MVC·s). There were no differences in the power variables between STAs. The primary finding was that increasing the STA from 72° to 82° enabled triathletes’ to maintain power production, while significantly reducing the muscular activation of the biceps femoris muscle. Key Points Road cyclists claim that bicycle seat tube angles between 72° and 76° are most effective for optimal performance in racing. Triathletes typically use seat tube angles greater than 76°. It is thought that a seat tube angle greater than 76° facilitates a smoother bike to run transition in the triathlon. Increasing the seat tube angle from 72 to 82 enabled triathletes’ to maintain power production, while significantly reducing the muscular activation of the biceps femoris muscle. Reduced hamstring muscular activation in the triathlon frame (82 seat tube angle) may serve to reduce hamstring tightness following the bike phase of the triathlon, allowing the runner to use a longer stride length. PMID:24198678

SU-E-T-230: Creating a Large Number of Focused Beams with Variable Patient Head Tilt to Improve Dose Fall-Off for Brain Radiosurgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiu, J; Ma, L

2015-06-15

Purpose: To develop a treatment delivery and planning strategy by increasing the number of beams to minimize dose to brain tissue surrounding a target, while maximizing dose coverage to the target. Methods: We analyzed 14 different treatment plans via Leksell PFX and 4C. For standardization, single tumor cases were chosen. Original treatment plans were compared with two optimized plans. The number of beams was increased in treatment plans by varying tilt angles of the patient head, while maintaining original isocenter and the beam positions in the x-, y- and z-axes, collimator size, and beam blocking. PFX optimized plans increased beammore » numbers with three pre-set tilt angles, 70, 90, 110, and 4C optimized plans increased beam numbers with tilt angles increasing arbitrarily from range of 30 to 150 degrees. Optimized treatment plans were compared dosimetrically with original treatment plans. Results: Comparing total normal tissue isodose volumes between original and optimized plans, the low-level percentage isodose volumes decreased in all plans. Despite the addition of multiple beams up to a factor of 25, beam-on times for 1 tilt angle versus 3 or more tilt angles were comparable (<1 min.). In 64% (9/14) of the studied cases, the volume percentage decrease by >5%, with the highest value reaching 19%. The addition of more tilt angles correlates to a greater decrease in normal brain irradiated volume. Selectivity and coverage for original and optimized plans remained comparable. Conclusion: Adding large number of additional focused beams with variable patient head tilt shows improvement for dose fall-off for brain radiosurgery. The study demonstrates technical feasibility of adding beams to decrease target volume.« less

ANALYSIS ON THE VARIATION OF MEDIAL ROTATION VALUES ACCORDING TO THE POSITION OF THE HUMERAL DIAPHYSIS.

PubMed

Miyazaki, Alberto Naoki; Fregoneze, Marcelo; Santos, Pedro Doneux; da Silva, Luciana Andrade; do Val Sella, Guilherme; Cohen, Carina; Busin Giora, Taís Stedile; Checchia, Sergio Luiz; Raia, Fabio; Pekelman, Hélio; Cymrot, Raquel

2012-01-01

To analyze the validity of measurements of medial rotation (MR) of the shoulder, using vertebral levels, according to the variation in the position of the humeral diaphysis, and to test the bi-goniometer as a new measuring instrument. 140 shoulders (70 patients) were prospectively evaluated in cases presenting unilateral shoulder MR limitation. The vertebral level was evaluated by means of a visual scale and was correlated with the angle obtained according to the position of the humeral diaphysis, using the bi-goniometer developed with the Department of Mechanical Engineering of Mackenzie University. The maximum vertebral level reached through MR on the unaffected side ranged from T3 to T12, and on the affected side, from T6 to the trochanter. Repositioning of the affected limb in MR according to the angular values on the normal side showed that 57.13% of the patients reached lower levels, between the sacrum, gluteus and trochanter. From analysis on the maximum vertebral level attained and the variation between the affected angle x (frontal plane: abduction and MR of the shoulder) and the unaffected angle x in MR, we observed that the greater the angle of the diaphyseal axis was, the lower the variation in the vertebral level attained was. From evaluating the linear correlation between the variables of difference in maximum vertebral level reached and variation in the affected angle y (extension and abduction of the shoulder) and the unaffected angle y in MR, we observed that there was no well-established linear relationship between these variables. Measurement of MR using vertebral levels does not correspond to the real values, since it varies according to the positioning of the humeral diaphysis.

ANALYSIS ON THE VARIATION OF MEDIAL ROTATION VALUES ACCORDING TO THE POSITION OF THE HUMERAL DIAPHYSIS

PubMed Central

Miyazaki, Alberto Naoki; Fregoneze, Marcelo; Santos, Pedro Doneux; da Silva, Luciana Andrade; do Val Sella, Guilherme; Cohen, Carina; Busin Giora, Taís Stedile; Checchia, Sergio Luiz; Raia, Fabio; Pekelman, Hélio; Cymrot, Raquel

2015-01-01

Objective: To analyze the validity of measurements of medial rotation (MR) of the shoulder, using vertebral levels, according to the variation in the position of the humeral diaphysis, and to test the bi-goniometer as a new measuring instrument. Methods: 140 shoulders (70 patients) were prospectively evaluated in cases presenting unilateral shoulder MR limitation. The vertebral level was evaluated by means of a visual scale and was correlated with the angle obtained according to the position of the humeral diaphysis, using the bi-goniometer developed with the Department of Mechanical Engineering of Mackenzie University. Results: The maximum vertebral level reached through MR on the unaffected side ranged from T3 to T12, and on the affected side, from T6 to the trochanter. Repositioning of the affected limb in MR according to the angular values on the normal side showed that 57.13% of the patients reached lower levels, between the sacrum, gluteus and trochanter. From analysis on the maximum vertebral level attained and the variation between the affected angle x (frontal plane: abduction and MR of the shoulder) and the unaffected angle x in MR, we observed that the greater the angle of the diaphyseal axis was, the lower the variation in the vertebral level attained was. From evaluating the linear correlation between the variables of difference in maximum vertebral level reached and variation in the affected angle y (extension and abduction of the shoulder) and the unaffected angle y in MR, we observed that there was no well-established linear relationship between these variables. Conclusion: Measurement of MR using vertebral levels does not correspond to the real values, since it varies according to the positioning of the humeral diaphysis. PMID:27047845

Aerodynamic Measurements of a Variable-Speed Power-Turbine Blade Section in a Transonic Turbine Cascade

NASA Technical Reports Server (NTRS)

Flegel, Ashlie B.

2014-01-01

The purpose of this thesis is to document the impact of incidence angle and Reynolds number variations on the three-dimensional flow field and midspan loss and turning of a two-dimensional section of a variable-speed power-turbine (VSPT) rotor blade. Aerodynamic measurements were obtained in a transonic linear cascade at NASA Glenn Research Center in Cleveland, Ohio. Steady-state data were obtained for 10 incidence angles ranging from +15.8deg to -51.0deg. At each angle, data were acquired at five flow conditions with the exit Reynolds number (based on axial chord) varying over an order-of-magnitude from 2.12×105 to 2.12×106. Data were obtained at the design exit Mach number of 0.72 and at a reduced exit Mach number of 0.35 as required to achieve the lowest Reynolds number. Midspan tota lpressure and exit flow angle data were acquired using a five-hole pitch/yaw probe surveyed on a plane located 7.0 percent axial-chord downstream of the blade trailing edge plane. The survey spanned three blade passages. Additionally, three-dimensional half-span flow fields were examined with additional probe survey data acquired at 26 span locations for two key incidence angles of +5.8deg and -36.7deg. Survey data near the endwall were acquired with a three-hole boundary-layer probe. The data were integrated to determine average exit total-pressure and flow angle as functions of incidence and flow conditions. The data set also includes blade static pressures measured on four spanwise planes and endwall static pressures.

Dependence of short and intermediate-range order on preparation in experimental and modeled pure a-Si

DOE PAGES

Holmstrom, Eero; Haberl, Bianca; Pakarinen, Olli H.; ...

2016-02-20

Variability in the short-to-intermediate range order of pure amorphous silicon prepared by different experimental and computational techniques is probed by measuring mass density, atomic coordination, bond-angle deviation, and dihedral angle deviation. It is found that there is significant variability in order parameters at these length scales in this archetypal covalently bonded, monoatomic system. This diversity strongly reflects preparation technique and thermal history in both experimental and simulated systems. Experiment and simulation do not fully quantitatively agree, partly due to differences in the way parameters are accessed. However, qualitative agreement in the trends is identified. Relaxed forms of amorphous silicon closelymore » resemble continuous random networks generated by a hybrid method of bond-switching Monte Carlo and molecular dynamics simulation. As-prepared ion implanted amorphous silicon can be adequately modeled using a structure generated from amorphization via ion bombardement using energetic recoils. Preparation methods which narrowly avoid crystallization such as experimental pressure-induced amorphization or simulated melt-quenching result in inhomogeneous structures that contain regions with significant variations in atomic ordering. Ad hoc simulated structures containing small (1 nm) diamond cubic crystal inclusions were found to possess relatively high bond-angle deviations and low dihedral angle deviations, a trend that could not be reconciled with any experimental material.« less

Anisotropy in thermal conductivity of graphite flakes–SiC{sub p}/matrix composites: Implications in heat sinking design for thermal management applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Molina, J.M., E-mail: jmmj@ua.es; Departamento de Física Aplicada, Universidad de Alicante, Ap. 99, E-03080 Alicante; Departamento de Química Inorgánica, Universidad de Alicante, Ap. 99, | E-03080 Alicante

2015-11-15

Within the frame of heat dissipation for electronics, a very interesting family of anisotropic composite materials, fabricated by liquid infiltration of a matrix into preforms of oriented graphite flakes and SiC particles, has been recently proposed. Aiming to investigate the implications of the inherent anisotropy of these composites on their thermal conductivity, and hence on their potential applications, materials with matrices of Al–12 wt.% Si alloy and epoxy polymer have been fabricated. Samples have been cut at a variable angle with respect to the flakes plane and thermal conductivity has been measured by means of two standard techniques, namely, steadymore » state technique and laser flash method. Experimental results are presented and discussed in terms of current models, from which important technological implications for heat sinking design can be derived. - Highlights: • Anisotropy in thermal conductivity of graphite flakes-based composites is evaluated. • Samples are cut in a direction forming a variable angle with the oriented flakes. • For angles 0° and 90°, thermal conductivity does not depend on sample geometry. • For intermediate angles, thermal conductivity strongly depends on sample geometry. • “Thin” samples must be thicker than 600 μm, “thick” samples must be encapsulated.« less

Characterization facility for magneto-optic media and systems

NASA Technical Reports Server (NTRS)

Mansuripur, M.; Fu, H.; Gadetsky, S.; Sugaya, S.; Wu, T. H.; Zambuto, J.; Gerber, R.; Goodman, T.; Erwin, J. K.

1993-01-01

Objectives of this research are: (1) to measure the hysteresis loop, Kerr rotation angle, anisotropy energy profile, Hall voltage, and magnetoresistance of thin-film magneto-optic media using our loop-tracer; (2) measure the wavelength-dependence of the Kerr rotation angle, Theta(sub k), and ellipticity, epsilon(sub k), for thin-film media using our magneto-optic Kerr spectrometer (MOKS); (3) measure the dielectric tensor of thin-film and multilayer samples using our variable-angle magneto-optic ellipsometer (VAMOE); (4) measure the hysteresis loop, coercivity, remanent magnetization, saturation magnetization, and anisotropy energy constant for thin film magnetic media using vibrating sample magnetometry; (5) observe small magnetic domains and investigate their interaction with defects using magnetic force microscopy; (6) perform static read/write/erase experiments on thin-film magneto-optic media using our static test station; (7) integrate the existing models of magnetization, magneto-optic effects, coercivity, and anisotropy in an interactive and user-friendly environment, and analyze the characterization data obtained in the various experiments, using this modeling package; (8) measure focusing- and tracking-error signals on a static testbed, determine the 'feedthrough' for various focusing schemes, investigate the effects of polarization and birefringence, and compare the results with diffraction-based calculations; and (9) measure the birefringence of optical disk substrates using two variable angle ellipsometers.

20 MHz Forward-imaging Single-element Beam Steering with an Internal Rotating Variable-Angle Reflecting Surface: Wire phantom and Ex vivo pilot study

PubMed Central

Raphael, David T.; Li, Xiang; Park, Jinhyoung; Chen, Ruimin; Chabok, Hamid; Barukh, Arthur; Zhou, Qifa; Elgazery, Mahmoud; Shung, K. Kirk

2012-01-01

Feasibility is demonstrated for a forward-imaging beam steering system involving a single-element 20 MHz angled-face acoustic transducer combined with an internal rotating variable-angle reflecting surface (VARS). Rotation of the VARS structure, for a fixed position of the transducer, generates a 2-D angular sector scan. If these VARS revolutions were to be accompanied by successive rotations of the single-element transducer, 3-D imaging would be achieved. In the design of this device, a single-element 20 MHz PMN-PT press-focused angled-face transducer is focused on the circle of midpoints of a micro-machined VARS within the distal end of an endoscope. The 2-D imaging system was tested in water bath experiments with phantom wire structures at a depth of 10 mm, and exhibited an axial resolution of 66 μm and a lateral resolution of 520 μm. Chirp coded excitation was used to enhance the signal-to-noise ratio, and to increase the depth of penetration. Images of an ex vivo cow eye were obtained. This VARS-based approach offers a novel forward-looking beam-steering method, which could be useful in intra-cavity imaging. PMID:23122968

20 MHz forward-imaging single-element beam steering with an internal rotating variable-angle reflecting surface: Wire phantom and ex vivo pilot study.

PubMed

Raphael, David T; Li, Xiang; Park, Jinhyoung; Chen, Ruimin; Chabok, Hamid; Barukh, Arthur; Zhou, Qifa; Elgazery, Mahmoud; Shung, K Kirk

2013-02-01

Feasibility is demonstrated for a forward-imaging beam steering system involving a single-element 20MHz angled-face acoustic transducer combined with an internal rotating variable-angle reflecting surface (VARS). Rotation of the VARS structure, for a fixed position of the transducer, generates a 2-D angular sector scan. If these VARS revolutions were to be accompanied by successive rotations of the single-element transducer, 3-D imaging would be achieved. In the design of this device, a single-element 20MHz PMN-PT press-focused angled-face transducer is focused on the circle of midpoints of a micro-machined VARS within the distal end of an endoscope. The 2-D imaging system was tested in water bath experiments with phantom wire structures at a depth of 10mm, and exhibited an axial resolution of 66μm and a lateral resolution of 520μm. Chirp coded excitation was used to enhance the signal-to-noise ratio, and to increase the depth of penetration. Images of an ex vivo cow eye were obtained. This VARS-based approach offers a novel forward-looking beam-steering method, which could be useful in intra-cavity imaging. Copyright © 2012 Elsevier B.V. All rights reserved.

Gaze and viewing angle influence visual stabilization of upright posture

PubMed Central

Ustinova, KI; Perkins, J

2011-01-01

Focusing gaze on a target helps stabilize upright posture. We investigated how this visual stabilization can be affected by observing a target presented under different gaze and viewing angles. In a series of 10-second trials, participants (N = 20, 29.3 ± 9 years of age) stood on a force plate and fixed their gaze on a figure presented on a screen at a distance of 1 m. The figure changed position (gaze angle: eye level (0°), 25° up or down), vertical body orientation (viewing angle: at eye level but rotated 25° as if leaning toward or away from the participant), or both (gaze and viewing angle: 25° up or down with the rotation equivalent of a natural visual perspective). Amplitude of participants’ sagittal displacement, surface area, and angular position of the center of gravity (COG) were compared. Results showed decreased COG velocity and amplitude for up and down gaze angles. Changes in viewing angles resulted in altered body alignment and increased amplitude of COG displacement. No significant changes in postural stability were observed when both gaze and viewing angles were altered. Results suggest that both the gaze angle and viewing perspective may be essential variables of the visuomotor system modulating postural responses. PMID:22398978

Judgements about the relation between force and trajectory variables in verbally described ballistic projectile motion.

PubMed

White, Peter A

2013-01-01

How accurate are explicit judgements about familiar forms of object motion, and how are they made? Participants judged the relations between force exerted in kicking a soccer ball and variables that define the trajectory of the ball: launch angle, maximum height attained, and maximum distance reached. Judgements tended to conform to a simple heuristic that judged force tends to increase as maximum height and maximum distance increase, with launch angle not being influential. Support was also found for the converse prediction, that judged maximum height and distance tend to increase as the amount of force described in the kick increases. The observed judgemental tendencies did not resemble the objective relations, in which force is a function of interactions between the trajectory variables. This adds to a body of research indicating that practical knowledge based on experiences of actions on objects is not available to the processes that generate judgements in higher cognition and that such judgements are generated by simple rules that do not capture the objective interactions between the physical variables.

Vibration Analysis of a Split Path Gearbox

NASA Technical Reports Server (NTRS)

Krantz, Timothy L.; Rashidi, Majid

1995-01-01

Split path gearboxes can be attractive alternatives to the common planetary designs for rotorcraft, but because they have seen little use, they are relatively high risk designs. To help reduce the risk of fielding a rotorcraft with a split path gearbox, the vibration and dynamic characteristics of such a gearbox were studied. A mathematical model was developed by using the Lagrangian method, and it was applied to study the effect of three design variables on the natural frequencies and vibration energy of the gearbox. The first design variable, shaft angle, had little influence on the natural frequencies. The second variable, mesh phasing, had a strong effect on the levels of vibration energy, with phase angles of 0 deg and 180 deg producing low vibration levels. The third design variable, the stiffness of the shafts connecting the spur gears to the helical pinions, strongly influenced the natural frequencies of some of the vibration modes, including two of the dominant modes. We found that, to achieve the lowest level of vibration energy, the natural frequencies of these two dominant modes should be less than those of the main excitation sources.

Communication: Wigner functions in action-angle variables, Bohr-Sommerfeld quantization, the Heisenberg correspondence principle, and a symmetrical quasi-classical approach to the full electronic density matrix

DOE PAGES

Miller, William H.; Cotton, Stephen J.

2016-08-28

It is pointed out that the classical phase space distribution in action-angle (a-a) variables obtained from a Wigner function depends on how the calculation is carried out: if one computes the standard Wigner function in Cartesian variables (p, x), and then replaces p and x by their expressions in terms of a-a variables, one obtains a different result than if the Wigner function is computed directly in terms of the a-a variables. Furthermore, the latter procedure gives a result more consistent with classical and semiclassical theory - e.g., by incorporating the Bohr-Sommerfeld quantization condition (quantum states defined by integer valuesmore » of the action variable) as well as the Heisenberg correspondence principle for matrix elements of an operator between such states - and has also been shown to be more accurate when applied to electronically non-adiabatic applications as implemented within the recently developed symmetrical quasi-classical (SQC) Meyer-Miller (MM) approach. Moreover, use of the Wigner function (obtained directly) in a-a variables shows how our standard SQC/MM approach can be used to obtain off-diagonal elements of the electronic density matrix by processing in a different way the same set of trajectories already used (in the SQC/MM methodology) to obtain the diagonal elements.« less

Communication: Wigner functions in action-angle variables, Bohr-Sommerfeld quantization, the Heisenberg correspondence principle, and a symmetrical quasi-classical approach to the full electronic density matrix.

PubMed

Miller, William H; Cotton, Stephen J

2016-08-28

It is pointed out that the classical phase space distribution in action-angle (a-a) variables obtained from a Wigner function depends on how the calculation is carried out: if one computes the standard Wigner function in Cartesian variables (p, x), and then replaces p and x by their expressions in terms of a-a variables, one obtains a different result than if the Wigner function is computed directly in terms of the a-a variables. Furthermore, the latter procedure gives a result more consistent with classical and semiclassical theory-e.g., by incorporating the Bohr-Sommerfeld quantization condition (quantum states defined by integer values of the action variable) as well as the Heisenberg correspondence principle for matrix elements of an operator between such states-and has also been shown to be more accurate when applied to electronically non-adiabatic applications as implemented within the recently developed symmetrical quasi-classical (SQC) Meyer-Miller (MM) approach. Moreover, use of the Wigner function (obtained directly) in a-a variables shows how our standard SQC/MM approach can be used to obtain off-diagonal elements of the electronic density matrix by processing in a different way the same set of trajectories already used (in the SQC/MM methodology) to obtain the diagonal elements.

Molecular envelope and atomic model of an anti-terminated glyQS T-box regulator in complex with tRNAGly.

PubMed

Chetnani, Bhaskar; Mondragón, Alfonso

2017-07-27

A T-box regulator or riboswitch actively monitors the levels of charged/uncharged tRNA and participates in amino acid homeostasis by regulating genes involved in their utilization or biosynthesis. It has an aptamer domain for cognate tRNA recognition and an expression platform to sense the charge state and modulate gene expression. These two conserved domains are connected by a variable linker that harbors additional secondary structural elements, such as Stem III. The structural basis for specific tRNA binding is known, but the structural basis for charge sensing and the role of other elements remains elusive. To gain new structural insights on the T-box mechanism, a molecular envelope was calculated from small angle X-ray scattering data for the Bacillus subtilis glyQS T-box riboswitch in complex with an uncharged tRNAGly. A structural model of an anti-terminated glyQS T-box in complex with its cognate tRNAGly was derived based on the molecular envelope. It shows the location and relative orientation of various secondary structural elements. The model was validated by comparing the envelopes of the wild-type complex and two variants. The structural model suggests that in addition to a possible regulatory role, Stem III could aid in preferential stabilization of the T-box anti-terminated state allowing read-through of regulated genes. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Practical way to avoid spurious geometrical contributions in Brillouin light scattering experiments at variable scattering angles.

PubMed

Battistoni, Andrea; Bencivenga, Filippo; Fioretto, Daniele; Masciovecchio, Claudio

2014-10-15

In this Letter, we present a simple method to avoid the well-known spurious contributions in the Brillouin light scattering (BLS) spectrum arising from the finite aperture of collection optics. The method relies on the use of special spatial filters able to select the scattered light with arbitrary precision around a given value of the momentum transfer (Q). We demonstrate the effectiveness of such filters by analyzing the BLS spectra of a reference sample as a function of scattering angle. This practical and inexpensive method could be an extremely useful tool to fully exploit the potentiality of Brillouin acoustic spectroscopy, as it will easily allow for effective Q-variable experiments with unparalleled luminosity and resolution.

Interference of Tail Surfaces and Wing and Fuselage from Tests of 17 Combinations in the N.A.C.A. Variable-Density Tunnel

NASA Technical Reports Server (NTRS)

Sherman, Albert

1939-01-01

An investigation of the interference associated with tail surfaces added to wing-fuselage combinations was included in the interference program in progress in the NACA variable-density tunnel. The results indicate that, in aerodynamically clean combinations, the increment of the high-speed drag can be estimated from section characteristics within useful limits of accuracy. The interference appears mainly as effects on the downwash angle and as losses in the tail effectiveness and varies with the geometry of the combination. An interference burble, which markedly increases the glide-path angle and the stability in pitch before the actual stall, may be considered a means of obtaining satisfactory stalling characteristics for complete combination.

Solving the Inverse-Square Problem with Complex Variables

ERIC Educational Resources Information Center

Gauthier, N.

2005-01-01

The equation of motion for a mass that moves under the influence of a central, inverse-square force is formulated and solved as a problem in complex variables. To find the solution, the constancy of angular momentum is first established using complex variables. Next, the complex position coordinate and complex velocity of the particle are assumed…

The low salinity effect at high temperatures

DOE PAGES

Xie, Quan; Brady, Patrick V.; Pooryousefy, Ehsan; ...

2017-04-05

The mechanism(s) of low salinity water flooding (LSWF) must be better understood at high temperatures and pressures if the method is to be applied in high T/P kaolinite-bearing sandstone reservoirs. We measured contact angles between a sandstone and an oil (acid number, AN = 3.98 mg KOH/g, base number, BN = 1.3 mg KOH/g) from a reservoir in the Tarim Field in western China in the presence of various water chemistries. We examined the effect of aqueous ionic solutions (formation brine, 100X diluted formation brine, and softened water), temperature (60, 100 and 140 °C) and pressure (20, 30, 40, andmore » 50 MPa) on the contact angle. We also measured the zeta potential of the oil/water and water/rock interfaces to calculate oil/brine/rock disjoining pressures. A surface complexation model was developed to interpret contact angle measurements and compared with DLVO theory predictions. Contact angles were greatest in formation water, followed by the softened water, and low salinity water at the same pressure and temperature. Contact angles increased slightly with temperature, whereas pressure had little effect. DLVO and surface complexation modelling predicted similar wettability trends and allow reasonably accurate interpretation of core-flood results. Water chemistry has a much larger impact on LSWF than reservoir temperature and pressure. As a result, low salinity water flooding should work in high temperature and high pressure kaolinite-bearing sandstone reservoirs.« less

The low salinity effect at high temperatures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xie, Quan; Brady, Patrick V.; Pooryousefy, Ehsan

The mechanism(s) of low salinity water flooding (LSWF) must be better understood at high temperatures and pressures if the method is to be applied in high T/P kaolinite-bearing sandstone reservoirs. We measured contact angles between a sandstone and an oil (acid number, AN = 3.98 mg KOH/g, base number, BN = 1.3 mg KOH/g) from a reservoir in the Tarim Field in western China in the presence of various water chemistries. We examined the effect of aqueous ionic solutions (formation brine, 100X diluted formation brine, and softened water), temperature (60, 100 and 140 °C) and pressure (20, 30, 40, andmore » 50 MPa) on the contact angle. We also measured the zeta potential of the oil/water and water/rock interfaces to calculate oil/brine/rock disjoining pressures. A surface complexation model was developed to interpret contact angle measurements and compared with DLVO theory predictions. Contact angles were greatest in formation water, followed by the softened water, and low salinity water at the same pressure and temperature. Contact angles increased slightly with temperature, whereas pressure had little effect. DLVO and surface complexation modelling predicted similar wettability trends and allow reasonably accurate interpretation of core-flood results. Water chemistry has a much larger impact on LSWF than reservoir temperature and pressure. As a result, low salinity water flooding should work in high temperature and high pressure kaolinite-bearing sandstone reservoirs.« less

On the complexity of Engh and Huber refinement restraints: the angle τ as example

DOE Office of Scientific and Technical Information (OSTI.GOV)

Touw, Wouter G.; Vriend, Gert, E-mail: vriend@cmbi.ru.nl

2010-12-01

The angle τ (backbone N—C{sup α}—C) is the most contested Engh and Huber refinement target parameter. It is shown that this parameter is ‘correct’ as a PDB-wide average, but can be improved by taking into account residue types, secondary structures and many other aspects of our knowledge of the biophysical relations between residue type and protein structure. The Engh and Huber parameters for bond lengths and bond angles have been used uncontested in macromolecular structure refinement from 1991 until very recently, despite critical discussion of their ubiquitous validity by many authors. An extensive analysis of the backbone angle τ (N—C{supmore » α}—C) illustrates that the Engh and Huber parameters can indeed be improved and a recent study [Tronrud et al. (2010 ▶), Acta Cryst. D66, 834–842] confirms these ideas. However, the present study of τ shows that improving the Engh and Huber parameters will be considerably more complex than simply making the parameters a function of the backbone ϕ, ψ angles. Many other aspects, such as the cooperativity of hydrogen bonds, the bending of secondary-structure elements and a series of biophysical aspects of the 20 amino-acid types, will also need to be taken into account. Different sets of Engh and Huber parameters will be needed for conceptually different refinement programs.« less

Evaluation of the Radiation Susceptibility of a 3D NAND Flash Memory

NASA Technical Reports Server (NTRS)

Chen, Dakai; Wilcox, Edward; Ladbury, Raymond; Seidleck, Christina; Kim, Hak; Phan, Anthony; LaBel, Kenneth

2017-01-01

We evaluated the heavy ion and proton-induced single-event effects (SEE) for a 3D NAND flash. The 3D NAND showed similar single-event upset (SEU) sensitivity to a planar NAND of similar density and performance in the multiple-cell level (MLC) storage mode. However, the single-level-cell (SLC) storage mode of the 3D NAND showed significantly reduced SEU susceptibility. Additionally, the 3D NAND showed less MBU susceptibility than the planar NAND, with reduced number of upset bits per byte and reduced cross sections overall. However, the 3D architecture exhibited angular sensitivities for both base and face angles, reflecting the anisotropic nature of the SEU vulnerability in space. Furthermore, the SEU cross section decreased with increasing fluence for both the 3D NAND and the latest generation planar NAND, indicating a variable upset rate for a space mission. These unique characteristics introduce complexity to traditional ground irradiation test procedures.

Variation of directional reflectance factors with structural changes of a developing alfalfa canopy

NASA Technical Reports Server (NTRS)

Kirchner, J. A.; Kimes, D. S.; Mcmurtrey, J. E., III

1982-01-01

Directional reflectance factors of an alfalfa canopy were determined and related to canopy structure, agronomic variables, and irradiance conditions at four periods during a cutting cycle. Nadir and off-nadir reflectance factors decreased with increasing biomass in Thematic Mapper band 3(0.63-0.69 micrometer) and increased with increasing biomass in band 4(0.76-0.90 micrometer). The sensor view angle had less impact on perceived reflectance as the alfalfa progressed from an erectophile canopy of stems after harvest to a near planophile canopy of leaves at maturity. Studies of directional reflectance are needed for testing and upgrading vegetation canopy models and to aid in the complex interpretation problems presented by aircraft scanners and pointable satellites where illumination and viewing geometries may vary widely. Distinct changes in the patterns of radiance observed by a sensor as structural and biomass changes occur are keys to monitoring the growth and condition of crops.

Detecting text in natural scenes with multi-level MSER and SWT

NASA Astrophysics Data System (ADS)

Lu, Tongwei; Liu, Renjun

2018-04-01

The detection of the characters in the natural scene is susceptible to factors such as complex background, variable viewing angle and diverse forms of language, which leads to poor detection results. Aiming at these problems, a new text detection method was proposed, which consisted of two main stages, candidate region extraction and text region detection. At first stage, the method used multiple scale transformations of original image and multiple thresholds of maximally stable extremal regions (MSER) to detect the text regions which could detect character regions comprehensively. At second stage, obtained SWT maps by using the stroke width transform (SWT) algorithm to compute the candidate regions, then using cascaded classifiers to propose non-text regions. The proposed method was evaluated on the standard benchmark datasets of ICDAR2011 and the datasets that we made our own data sets. The experiment results showed that the proposed method have greatly improved that compared to other text detection methods.

Virtual engine management simulator for educational purposes

NASA Astrophysics Data System (ADS)

Drosescu, R.

2017-10-01

This simulator was conceived as a software program capable of generating complex control signals, identical to those in the electronic management systems of modern spark ignition or diesel engines. Speed in rpm and engine load percentage defined by throttle opening angle represent the input variables in the simulation program and are graphically entered by two-meter instruments from the simulator central block diagram. The output signals are divided into four categories: synchronization and position of each cylinder, spark pulses for spark ignition engines, injection pulses and, signals for generating the knock window for each cylinder in the case of a spark ignition engine. The simulation program runs in real-time so each signal evolution reflects the real behavior on a physically thermal engine. In this way, the generated signals (ignition or injection pulses) can be used with additionally drivers to control an engine on the test bench.

Exact Solution for Capillary Bridges Properties by Shooting Method

NASA Astrophysics Data System (ADS)

Qiang-Nian, Li; Jia-Qi, Zhang; Feng-Xi, Zhou

2017-04-01

The investigation of liquid bridge force acting between wet particles has great significance in many fields. In this article, the exact solution of capillary force between two unequal-sized spherical particles is investigated. Firstly, The Young-Laplace equation with moving boundary is converted into a set of ordinary differential equations with two fix point boundary using variable substitution technique, in which the gravity effects have been neglected. The geometry of the liquid bridge between two particles is solved by shooting method. After that, the gorge method is applied to calculate the capillary-bridge force that is consists of contributions from the capillary suction and surface tension. Finally, the effect of various parameters including distance between two spheres, radii of spheres, and contact angles on the capillary force are investigated. It is shown that the presented approach is an efficient and accurate algorithm for capillary force between two particles in complex situations.

Optical Properties of Ferroelectric Epitaxial K0.5Na0.5NbO3 Films in Visible to Ultraviolet Range

PubMed Central

Pacherova, O.; Kocourek, T.; Jelinek, M.; Dejneka, A.; Tyunina, M.

2016-01-01

The complex index of refraction in the spectral range of 0.74 to 4.5 eV is studied by variable-angle spectroscopic ellipsometry in ferroelectric K0.5Na0.5NbO3 films. The 20-nm-thick cube-on-cube-type epitaxial films are grown on SrTiO3(001) and DyScO3(011) single-crystal substrates. The films are transparent and exhibit a significant difference between refractive indices Δn = 0.5 at photon energies below 3 eV. The energies of optical transitions are in the range of 3.15–4.30 eV and differ by 0.2–0.3 eV in these films. The observed behavior is discussed in terms of lattice strain and strain-induced ferroelectric polarization in epitaxial perovskite oxide films. PMID:27074042

Refraction of microwave signals by water vapor

NASA Technical Reports Server (NTRS)

Goldfinger, A. D.

1980-01-01

Tropospheric water vapor causes a refractive path length effect which is typically 5-10% of the 'dry' tropospheric effect and as large as several meters at elevation angles below 5 deg. The vertical water vapor profile is quite variable, and measurements of intensive atmospheric parameters such as temperature and humidity limited to the surface do not adequately predict the refractive effect. It is suggested that a water vapor refraction model that is a function of the amount of precipitable water alone can be successful at low elevation angles. From an extensive study of numerical ray tracings through radiosonde balloon data, such a model has been constructed. The model predicts the effect at all latitudes and elevation angles between 2 and 10 deg to an accuracy of better than 4% (11 cm at 3 deg elevation angle).

Thick photosensitive polyimide film side wall angle variability and scum improvement for IC packaging stress control

NASA Astrophysics Data System (ADS)

Mehta, Sohan Singh; Yeung, Marco; Mirza, Fahad; Raman, Thiagarajan; Longenbach, Travis; Morgan, Justin; Duggan, Mark; Soedibyo, Rio A.; Reidy, Sean; Rabie, Mohamed; Cho, Jae Kyu; Premachandran, C. S.; Faruqui, Danish

2018-03-01

In this paper, we demonstrate photosensitive polyimide (PSPI) profile optimization to effectively reduce stress concentrations and enable PSPI as protection package-induced stress. Through detailed package simulation, we demonstrate 45% reduction in stress as the sidewall angle (SWA) of PSPI is increased from 45 to 80 degrees in Cu pillar package types. Through modulation of coating and develop multi-step baking temperature and time, as well as dose energy and post litho surface treatments, we demonstrate a method for reliably obtaining PSPI sidewall angle >75 degree. Additionally, we experimentally validate the simulation findings that PSPI sidewall angle impacts chip package interaction (CPI). Finally, we conclude this paper with PSPI material and tool qualification requirements for future technology node based on current challenges.

Measurement of colour flow with the jet pull angle in tt-bar events using the ATLAS detector at √s = 8 TeV

DOE PAGES

Aad, G.

2015-09-26

The distribution and orientation of energy inside jets is predicted to be an experimental handle on colour connections between the hard-scatter quarks and gluons initiating the jets. This Letter presents a measurement of the distribution of one such variable, the jet pull angle. The pull angle is measured for jets produced in tt-bar events with one W boson decaying leptonically and the other decaying to jets using 20.3 fb –1 of data recorded with the ATLAS detector at a centre-of-mass energy of √s=8 TeV at the LHC. The jet pull angle distribution is corrected for detector resolution and acceptance effectsmore » and is compared to various models.« less

Measurement of colour flow with the jet pull angle in tt-bar events using the ATLAS detector at √s = 8 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aad, G.

The distribution and orientation of energy inside jets is predicted to be an experimental handle on colour connections between the hard-scatter quarks and gluons initiating the jets. This Letter presents a measurement of the distribution of one such variable, the jet pull angle. The pull angle is measured for jets produced in tt-bar events with one W boson decaying leptonically and the other decaying to jets using 20.3 fb –1 of data recorded with the ATLAS detector at a centre-of-mass energy of √s=8 TeV at the LHC. The jet pull angle distribution is corrected for detector resolution and acceptance effectsmore » and is compared to various models.« less

Topology-Optimized Multilayered Metaoptics

NASA Astrophysics Data System (ADS)

Lin, Zin; Groever, Benedikt; Capasso, Federico; Rodriguez, Alejandro W.; Lončar, Marko

2018-04-01

We propose a general topology-optimization framework for metasurface inverse design that can automatically discover highly complex multilayered metastructures with increased functionalities. In particular, we present topology-optimized multilayered geometries exhibiting angular phase control, including a single-piece nanophotonic metalens with angular aberration correction, as well as an angle-convergent metalens that focuses light onto the same focal spot regardless of the angle of incidence.

A Zonal Approach for the Solution of Coupled Euler and Potential Solutions of Flows with Complex Geometries.

DTIC Science & Technology

1987-06-01

obtained from: A simple numerical intergration scheme is employed to perform the integral in Equations (B2) and (86) along the dividing streamline. A 11 4...angle of attack was small, the dividing streamline remained almost horizontal in this case. Results of a higher angle of attack case, in which the mesh

The mapping of eccentricity and meridional angle onto orthogonal axes in the primary visual cortex: an activity-dependent developmental model.

PubMed

Philips, Ryan T; Chakravarthy, V Srinivasa

2015-01-01

Primate vision research has shown that in the retinotopic map of the primary visual cortex, eccentricity and meridional angle are mapped onto two orthogonal axes: whereas the eccentricity is mapped onto the nasotemporal axis, the meridional angle is mapped onto the dorsoventral axis. Theoretically such a map has been approximated by a complex log map. Neural models with correlational learning have explained the development of other visual maps like orientation maps and ocular-dominance maps. In this paper it is demonstrated that activity based mechanisms can drive a self-organizing map (SOM) into such a configuration that dilations and rotations of a particular image (in this case a rectangular bar) are mapped onto orthogonal axes. We further demonstrate using the Laterally Interconnected Synergetically Self Organizing Map (LISSOM) model, with an appropriate boundary and realistic initial conditions, that a retinotopic map which maps eccentricity and meridional angle to the horizontal and vertical axes respectively can be developed. This developed map bears a strong resemblance to the complex log map. We also simulated lesion studies which indicate that the lateral excitatory connections play a crucial role in development of the retinotopic map.

How is sagittal balance acquired during bipedal gait acquisition? Comparison of neonatal and adult pelves in three dimensions. Evolutionary implications.

PubMed

Tardieu, Christine; Bonneau, Noémie; Hecquet, Jérôme; Boulay, Christophe; Marty, Catherine; Legaye, Jean; Duval-Beaupère, Geneviève

2013-08-01

We compare adult and intact neonatal pelves, using a pelvic sagittal variable, the angle of sacral incidence, which presents significant correlations with vertebral curvature in adults and plays an important role in sagittal balance of the trunk on the lower limbs. Since the lumbar curvature develops in the child in association with gait acquisition, we expect a change in this angle during growth which could contribute to the acquisition of sagittal balance. To understand the mechanisms underlying the sagittal balance in the evolution of human bipedalism, we also measure the angle of incidence of hominid fossils. Fourty-seven landmarks were digitized on 50 adult and 19 intact neonatal pelves. We used a three-dimensional model of the pelvis (DE-VISU program) which calculates the angle of sacral incidence and related functional variables. Cross-sectional data from newborns and adults show that the angle of sacral incidence increases and becomes negatively correlated with the sacro-acetabular distance. During ontogeny the sacrum becomes curved, tends to sink down between the iliac blades as a wedge and moves backward in the sagittal plane relative to the acetabula, thus contributing to the backwards displacement of the center of gravity of the trunk. A chain of correlations links the degree of the sacral slope and of the angle of incidence, which is tightly linked with the lumbar lordosis. We sketch a model showing the coordinated changes occurring in the pelvis and vertebral column during the acquisition of bipedalism in infancy. In the australopithecine pelves, Sts 14 and AL 288-1, and in the Homo erectus Gona pelvis the angle of sacral incidence reaches the mean values of humans. Discussing the incomplete pelves of Ardipithecus ramidus, Australopithecus sediba and the Nariokotome Boy, we suggest how the functional linkage between pelvis and spine, observed in humans, could have emerged during hominid evolution. Copyright © 2013 Elsevier Ltd. All rights reserved.

Quantitative angle-insensitive flow measurement using relative standard deviation OCT.

PubMed

Zhu, Jiang; Zhang, Buyun; Qi, Li; Wang, Ling; Yang, Qiang; Zhu, Zhuqing; Huo, Tiancheng; Chen, Zhongping

2017-10-30

Incorporating different data processing methods, optical coherence tomography (OCT) has the ability for high-resolution angiography and quantitative flow velocity measurements. However, OCT angiography cannot provide quantitative information of flow velocities, and the velocity measurement based on Doppler OCT requires the determination of Doppler angles, which is a challenge in a complex vascular network. In this study, we report on a relative standard deviation OCT (RSD-OCT) method which provides both vascular network mapping and quantitative information for flow velocities within a wide range of Doppler angles. The RSD values are angle-insensitive within a wide range of angles, and a nearly linear relationship was found between the RSD values and the flow velocities. The RSD-OCT measurement in a rat cortex shows that it can quantify the blood flow velocities as well as map the vascular network in vivo .

Quantitative angle-insensitive flow measurement using relative standard deviation OCT

NASA Astrophysics Data System (ADS)

Zhu, Jiang; Zhang, Buyun; Qi, Li; Wang, Ling; Yang, Qiang; Zhu, Zhuqing; Huo, Tiancheng; Chen, Zhongping

2017-10-01

Incorporating different data processing methods, optical coherence tomography (OCT) has the ability for high-resolution angiography and quantitative flow velocity measurements. However, OCT angiography cannot provide quantitative information of flow velocities, and the velocity measurement based on Doppler OCT requires the determination of Doppler angles, which is a challenge in a complex vascular network. In this study, we report on a relative standard deviation OCT (RSD-OCT) method which provides both vascular network mapping and quantitative information for flow velocities within a wide range of Doppler angles. The RSD values are angle-insensitive within a wide range of angles, and a nearly linear relationship was found between the RSD values and the flow velocities. The RSD-OCT measurement in a rat cortex shows that it can quantify the blood flow velocities as well as map the vascular network in vivo.

Load monitoring of aerospace structures utilizing micro-electro-mechanical systems for static and quasi-static loading conditions

NASA Astrophysics Data System (ADS)

Martinez, M.; Rocha, B.; Li, M.; Shi, G.; Beltempo, A.; Rutledge, R.; Yanishevsky, M.

2012-11-01

The National Research Council Canada (NRC) has worked on the development of structural health monitoring (SHM) test platforms for assessing the performance of sensor systems for load monitoring applications. The first SHM platform consists of a 5.5 m cantilever aluminum beam that provides an optimal scenario for evaluating the ability of a load monitoring system to measure bending, torsion and shear loads. The second SHM platform contains an added level of structural complexity, by consisting of aluminum skins with bonded/riveted stringers, typical of an aircraft lower wing structure. These two load monitoring platforms are well characterized and documented, providing loading conditions similar to those encountered during service. In this study, a micro-electro-mechanical system (MEMS) for acquiring data from triads of gyroscopes, accelerometers and magnetometers is described. The system was used to compute changes in angles at discrete stations along the platforms. The angles obtained from the MEMS were used to compute a second, third or fourth order degree polynomial surface from which displacements at every point could be computed. The use of a new Kalman filter was evaluated for angle estimation, from which displacements in the structure were computed. The outputs of the newly developed algorithms were then compared to the displacements obtained from the linear variable displacement transducers connected to the platforms. The displacement curves were subsequently post-processed either analytically, or with the help of a finite element model of the structure, to estimate strains and loads. The estimated strains were compared with baseline strain gauge instrumentation installed on the platforms. This new approach for load monitoring was able to provide accurate estimates of applied strains and shear loads.

Higher coordinate gold(I) complexes with the weak Lewis base tri(4-fluorophenyl) phosphine. Synthesis, structural, luminescence, and DFT studies

NASA Astrophysics Data System (ADS)

Agbeworvi, George; Assefa, Zerihun; Sykora, Richard E.; Taylor, Jared; Crawford, Carlos

2016-03-01

The structures and spectroscopic properties of two high coordinate gold(I) phosphine complexes with the TFFPP=tri(4-fluorophenyl)phosphine ligand are reported. Synthesis in a 1:3 metal to ligand ratio provided the compound [AuCl(TFFPP)3] (2) that crystallize in the P 1 bar space group, where the asymmetric unit consists of three independent molecules. In all three sites, two sets of bond angles display distinctly different ranges. The three P-Au-P angles have average values of 117.92°, 117.57°, and 114.78° for sites A, B, and C, with the corresponding P-Au-Cl angles of 98.31°, 99.05°, and 103.38°, respectively. The chloride ion coordinates as the fourth ligand, at the corresponding Au-Cl distance of 2.7337, 2.6825, and 2.6951 Å for the three sites. This distance is longer by 0.40-0.45 Å than the Au-Cl distance found in the mono TFFPP complex 1 (2.285 Å) indicating a weakening of the Au-Cl interaction as the coordination number increases. In compound 3, [Au(TFFPP)3]Cl·½CH2Cl2·H2O, the structure consists of three phosphine ligands bound to the gold(I) atom, but the Cl- exists as uncoordinated counter anion. The structural differences observed in the two complexes are attributable to crystal-packing effects caused by the introduction of H-bonding as well as enhanced intra and inter-molecular π-interaction in 3. The photoluminescence of the complexes compared with that of the ligand show ligand centered emission perturbed by the metal coordination. Theoretical DFT studies conducted on these complexes supports assignments of the electronic transitions observed in these systems.

Study of the composition, structure, and optical properties of a-Si{sub 1-x}C{sub x}:H Left-Pointing-Angle-Bracket Er Right-Pointing-Angle-Bracket films erbium doped from the Er(pd){sub 3} complex compound

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kudoyarova, V. Kh., E-mail: kudoyarova@mail.ioffe.ru; Tolmachev, V. A.; Gushchina, E. V.

2013-03-15

Rutherford backscattering, IR spectroscopy, ellipsometry, and atomic-force microscopy are used to perform an integrated study of the composition, structure and optical properties of a-Si{sub 1-x}C{sub x}:H Left-Pointing-Angle-Bracket Er Right-Pointing-Angle-Bracket amorphous films. The technique employed to obtain the a-Si{sub 1-x}C{sub x}:H Left-Pointing-Angle-Bracket Er Right-Pointing-Angle-Bracket amorphous films includes the high-frequency decomposition of a mixture of gases, (SiH{sub 4}){sub a} + (CH{sub 4}){sub b}, and the simultaneous thermal evaporation of a complex compound, Er(pd){sub 3}. It is demonstrated that raising the amount of CH{sub 4} in the gas mixture results in an increase in the carbon content of the films under study andmore » an increase in the optical gap E{sub g}{sup opt} from 1.75 to 2.2 eV. Changes in the composition of a-Si{sub 1-x}C{sub x}:H Left-Pointing-Angle-Bracket Er Right-Pointing-Angle-Bracket amorphous films, accompanied, in turn, by changes in the optical constants, are observed in the IR spectra. The ellipsometric spectra obtained are analyzed in terms of multiple-parameter models. The conclusion is made on the basis of this analysis that the experimental and calculated spectra coincide well when variation in the composition of the amorphous films with that of the gas mixture is taken into account. The existence of a thin (6-8 nm) silicon-oxide layer on the surface of the films under study and the validity of using the double-layer model in ellipsometric calculations is confirmed by the results of structural analyses by atomic-force microscopy.« less

Spherical Coordinate Systems for Streamlining Suited Mobility Analysis

NASA Technical Reports Server (NTRS)

Benson, Elizabeth; Cowley, Matthew; Harvill, Lauren; Rajulu. Sudhakar

2015-01-01

Introduction: When describing human motion, biomechanists generally report joint angles in terms of Euler angle rotation sequences. However, there are known limitations in using this method to describe complex motions such as the shoulder joint during a baseball pitch. Euler angle notation uses a series of three rotations about an axis where each rotation is dependent upon the preceding rotation. As such, the Euler angles need to be regarded as a set to get accurate angle information. Unfortunately, it is often difficult to visualize and understand these complex motion representations. It has been shown that using a spherical coordinate system allows Anthropometry and Biomechanics Facility (ABF) personnel to increase their ability to transmit important human mobility data to engineers, in a format that is readily understandable and directly translatable to their design efforts. Objectives: The goal of this project was to use innovative analysis and visualization techniques to aid in the examination and comprehension of complex motions. Methods: This project consisted of a series of small sub-projects, meant to validate and verify a new method before it was implemented in the ABF's data analysis practices. A mechanical test rig was built and tracked in 3D using an optical motion capture system. Its position and orientation were reported in both Euler and spherical reference systems. In the second phase of the project, the ABF estimated the error inherent in a spherical coordinate system, and evaluated how this error would vary within the reference frame. This stage also involved expanding a kinematic model of the shoulder to include the rest of the joints of the body. The third stage of the project involved creating visualization methods to assist in interpreting motion in a spherical frame. These visualization methods will be incorporated in a tool to evaluate a database of suited mobility data, which is currently in development. Results: Initial results demonstrated that a spherical coordinate system is helpful in describing and visualizing the motion of a space suit. The system is particularly useful in describing the motion of the shoulder, where multiple degrees of freedom can lead to very complex motion paths.

Optimum Projection Angle for Attaining Maximum Distance in a Soccer Punt Kick

PubMed Central

Linthorne, Nicholas P.; Patel, Dipesh S.

2011-01-01

To produce the greatest horizontal distance in a punt kick the ball must be projected at an appropriate angle. Here, we investigated the optimum projection angle that maximises the distance attained in a punt kick by a soccer goalkeeper. Two male players performed many maximum-effort kicks using projection angles of between 10° and 90°. The kicks were recorded by a video camera at 100 Hz and a 2 D biomechanical analysis was conducted to obtain measures of the projection velocity, projection angle, projection height, ball spin rate, and foot velocity at impact. The player’s optimum projection angle was calculated by substituting mathematical equations for the relationships between the projection variables into the equations for the aerodynamic flight of a soccer ball. The calculated optimum projection angles were in agreement with the player’s preferred projection angles (40° and 44°). In projectile sports even a small dependence of projection velocity on projection angle is sufficient to produce a substantial shift in the optimum projection angle away from 45°. In the punt kicks studied here, the optimum projection angle was close to 45° because the projection velocity of the ball remained almost constant across all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle and so the optimum projection angle is well below 45°. Key points The optimum projection angle that maximizes the distance of a punt kick by a soccer goalkeeper is about 45°. The optimum projection angle is close to 45° because the projection velocity of the ball is almost the same at all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the optimum projection angle is well below 45° because the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle. PMID:24149315

Flow Observations with Tufts and Lampblack of the Stalling of Four Typical Airfoil Sections in the NACA Variable-density Tunnel

NASA Technical Reports Server (NTRS)

Abbott, Ira H; Sherman, Albert

1938-01-01

A preliminary investigation of the stalling processes of four typical airfoil sections was made over the critical range of the Reynolds Number. Motion pictures were taken of the movements of small silk tufts on the airfoil surface as the angle of attack increased through a range of angles including the stall. The boundary-layer flow also at certain angles of attack was indicated by the patterns formed by a suspension of lampblack in oil brushed onto the airfoil surface. These observations were analyzed together with corresponding force-test measurements to derive a picture of the stalling processes of airfoils.

Multiangular Contributions for Discriminate Seasonal Structural Changes in the Amazon Rainforest Using MODIS MAIAC Data

NASA Astrophysics Data System (ADS)

Moura, Y. M.; Hilker, T.; Galvão, L. S.; Santos, J. R.; Lyapustin, A.; Sousa, C. H. R. D.; McAdam, E.

2014-12-01

The sensitivity of the Amazon rainforests to climate change has received great attention by the scientific community due to the important role that this vegetation plays in the global carbon, water and energy cycle. The spatial and temporal variability of tropical forests across Amazonia, and their phenological, ecological and edaphic cycles are still poorly understood. The objective of this work was to infer seasonal and spatial variability of forest structure in the Brazilian Amazon based on anisotropy of multi-angle satellite observations. We used observations from the Moderate Resolution Imaging Spectroradiometer (MODIS/Terra and Aqua) processed by a new Multi-Angle Implementation Atmospheric Correction Algorithm (MAIAC) to investigate how multi-angular spectral response from satellite imagery can be used to analyze structural variability of Amazon rainforests. We calculated differences acquired from forward and backscatter reflectance by modeling the bi-directional reflectance distribution function to infer seasonal and spatial changes in vegetation structure. Changes in anisotropy were larger during the dry season than during the wet season, suggesting intra-annual changes in vegetation structure and density. However, there were marked differences in timing and amplitude depending on forest type. For instance differences between reflectance hotspot and darkspot showed more anisotropy in the open Ombrophilous forest than in the dense Ombrophilous forest. Our results show that multi-angle data can be useful for analyzing structural differences in various forest types and for discriminating different seasonal effects within the Amazon basin. Also, multi-angle data could help solve uncertainties about sensitivity of different tropical forest types to light versus rainfall. In conclusion, multi-angular information, as expressed by the anisotropy of spectral reflectance, may complement conventional studies and provide significant improvements over approaches that are based on vegetation indices alone.

Stability of uncertain impulsive complex-variable chaotic systems with time-varying delays.

PubMed

Zheng, Song

2015-09-01

In this paper, the robust exponential stabilization of uncertain impulsive complex-variable chaotic delayed systems is considered with parameters perturbation and delayed impulses. It is assumed that the considered complex-variable chaotic systems have bounded parametric uncertainties together with the state variables on the impulses related to the time-varying delays. Based on the theories of adaptive control and impulsive control, some less conservative and easily verified stability criteria are established for a class of complex-variable chaotic delayed systems with delayed impulses. Some numerical simulations are given to validate the effectiveness of the proposed criteria of impulsive stabilization for uncertain complex-variable chaotic delayed systems. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.