[Evaluation of upper cervical spine injury (C1-C2) with computed tomography].

PubMed

Siemianowicz, Anna; Baron, Jan; Wawrzynek, Wojciech; Koczy, Bogdan; Kasprowska, Sabina

2006-01-01

Cervical spine injuries are common and essential diagnostic problem. Diagnostic imaging is necessary for proper and effective treatment. Helical computed tomography (CT) and plain radiography are the basic diagnostic methods in cervical spine injuries. The purpose of this work was the comparison of CT examination of the upper cervical spine (CI-C2) with patients' clinical state. Twenty four patients (17 men and 7 women) were introduced into the study. The most common cause of cervical spine injuries were car accidents (48.5%). CT examination was performed in all patients. Six patients (25%) had multilevel injury, localized at C1-C2 level and in the lower part of cervical spine. The main pathology diagnosed by CT in the studied group was rotatory subluxation (66.6%). Eight patients (33.3%), with rotatory subluxation did not present any abnormalities in neurological examination performed immediately after the admission to the hospital. C1 and/or C2 fractures were diagnosed in 11 patients (45.8%), in some cases (in 3 patients - 12.5%) they were accompanied by rotatory subluxations. CT examination is the basic technique of diagnostic imaging in a case of cervical spine injuries. It enables quick, accurate and precise evaluation of bone structures and surrounding soft tissues. CT also enables multiplanar imaging and 3-dimentional imaging.

A study of safety and tolerability of rotatory vestibular input for preschool children

PubMed Central

Su, Wen-Ching; Lin, Chin-Kai; Chang, Shih-Chung

2015-01-01

The objectives of this study were to determine a safe rotatory vestibular stimulation input for preschool children and to study the effects of grade level and sex of preschool children during active, passive, clockwise, and counterclockwise rotation vestibular input. This study adopted purposive sampling with 120 children from three kindergarten levels (K1, K2, and K3) in Taiwan. The subjects ranged in age from 46 to 79 months of age (mean: 62.1 months; standard deviation =9.60). This study included testing with four types of vestibular rotations. The number, duration, and speed of rotations were recorded. The study found that the mean number of active rotations was 10.28; the mean duration of rotation was 24.17 seconds; and the mean speed was 2.29 seconds per rotation. The mean number of passive rotations was 23.04. The differences in number of rotations in clockwise, counterclockwise, active, and passive rotations were not statistically significant. Sex and grade level were not important related factors in the speed and time of active rotation. Different sexes, rotation methods (active, passive), and grades made significant differences in the number of rotations. The safety and tolerability of rotatory vestibular stimulation input data obtained in this study can provide useful reference data for therapists using sensory integration therapy. PMID:25657579

Vertigo and nystagmus in orthostatic hypotension.

PubMed

Choi, J-H; Seo, J-D; Kim, M-J; Choi, B-Y; Choi, Y R; Cho, B M; Kim, J S; Choi, K-D

2015-04-01

Generalized cerebral ischaemia from cardiovascular dysfunction usually leads to presyncopal dizziness, but several studies reported a higher frequency of rotatory vertigo in cardiovascular patients. Whether generalized cerebral ischaemia due to cardiovascular disorders may produce objective vestibular dysfunction was investigated. Thirty-three patients with orthostatic dizziness/vertigo due to profound orthostatic hypotension and 30 controls were recruited. All participants underwent recording of eye movements during two orthostatic challenging tests: the Schellong and the squatting-standing tests. Most patients had neuroimaging, and patients with abnormal eye movements were subjected to follow-up evaluations. Symptoms associated with orthostatic dizziness/vertigo included blurred vision, fainting and tinnitus. Ten (30%) of 33 patients developed rotatory vertigo and nystagmus during the Schellong (n = 5) or squatting-standing test (n = 5). Four of them showed pure downbeat nystagmus whilst five had downbeat and horizontal nystagmus with or without torsional component. Patients with orthostatic nystagmus had shorter duration of orthostatic intolerance than those without nystagmus (1.0 ± 1.6 vs. 11.0 ± 9.7 months, P < 0.001). In two patients, orthostatic nystagmus disappeared during follow-up despite the persistence of profound orthostatic hypotension. Generalized cerebral ischaemia caused by orthostatic hypotension induces rotatory vertigo due to objective vestibular dysfunction. The presence of orthostatic vertigo and nystagmus has an association with the duration of orthostatic intolerance. © 2014 EAN.

Transverse vibration of Bernoulli Euler beams carrying point masses and taking into account their rotatory inertia: Exact solution

NASA Astrophysics Data System (ADS)

Maiz, Santiago; Bambill, Diana V.; Rossit, Carlos A.; Laura, P. A. A.

2007-06-01

The situation of structural elements supporting motors or engines attached to them is usual in technological applications. The operation of the machine may introduce severe dynamic stresses on the beam. It is important, then, to know the natural frequencies of the coupled beam-mass system, in order to obtain a proper design of the structural elements. An exact solution for the title problem is obtained in closed-form fashion, considering general boundary conditions by means of translational and rotatory springs at both ends. The model allows to analyze the influence of the masses and their rotatory inertia on the dynamic behavior of beams with all the classic boundary conditions, and also, as particular cases, to determine the frequencies of continuous beams.

The Influence of Meniscal and Anterolateral Capsular Injury on Knee Laxity in Patients With Anterior Cruciate Ligament Injuries.

PubMed

Musahl, Volker; Rahnemai-Azar, Ata A; Costello, Joanna; Arner, Justin W; Fu, Freddie H; Hoshino, Yuichi; Lopomo, Nicola; Samuelsson, Kristian; Irrgang, James J

2016-12-01

The role of the anterolateral capsule (ALC) as a secondary restraint to quantitative rotatory laxity of patients with an anterior cruciate ligament (ACL) injury is currently debated. The purpose was to determine the influence of concomitant ALC injuries as well as injuries to other soft tissue structures on rotatory knee laxity in patients with an ACL injury. It was hypothesized that a concomitant ALC injury would be associated with increased rotatory knee laxity as measured during a quantitative pivot-shift test. Cross-sectional study; Level of evidence, 3. Forty-one patients with an ACL injury (average age, 23 ± 6.9 years) were enrolled. Two blinded musculoskeletal radiologists reviewed magnetic resonance imaging (MRI) scans for the presence of ACL injuries and concomitant soft tissue injuries including the ALC, medial collateral ligament, lateral collateral ligament, posterolateral corner, medial meniscus, and lateral meniscus. A standardized pivot-shift test was performed under anesthesia, and rotatory laxity was quantified according to anterior translation of the lateral tibial compartment during the pivot-shift maneuver. The Student t test was used to analyze the data. Statistical significance was set at P < .05. A complete ACL rupture was confirmed in all of the patients. MRI evidence of an ALC injury was observed in 21 (51%) of the patients. Patients with MRI evidence of an ALC injury had significantly higher rotatory knee laxity (3.6 ± 1.5 mm) compared with those without an ALC injury (2.7 ± 1.5 mm; P = .04). Lateral and medial meniscus injuries were detected in 17 (41%) and 19 (46%) patients, respectively. Patients with MRI evidence of either a medial meniscus injury or lateral meniscus injury had significantly higher rotatory knee laxity compared with patients without these injuries (medial meniscus: 3.7 ± 1.4 mm vs 2.7 ± 1.6 mm, respectively; lateral meniscus: 3.7 ± 1.7 mm vs 2.7 ± 1.3 mm, respectively) (P = .03 for both). MRI evidence of a concomitant injury to the ALC, medial meniscus, or lateral meniscus is associated with increased knee rotatory laxity in patients with an ACL injury. These structures may function as important secondary stabilizers in an ACL-injured knee. Careful assessment and proper treatment of injuries to these secondary stabilizers should be considered, especially in knees with a high level of the pivot shift. © 2016 The Author(s).

[Finite element analysis of lumbar pelvic and proximal femur model with simulate lumbar rotatory manipulation].

PubMed

Hu, Hua; Xiong, Chang-Yuan; Han, Guo-Wu

2012-07-01

To study the changes of displacement and stress in the model of lumbar pelvic and proximal femur during lumbar rotatory manipulation. The date of lumbar pelvic and proximal femur CT scan by Mimics 10.01 software was established a lumbar pelvic and proximal femur geometric model, then the model was modified with Geomagic 9, at last the modified model was imported into hypermesh 10 and meshed with tetrahedron, at the same time,add disc and ligaments. According to the principle of lumbar rotatory manipulation,the lumbar rotatory manipulation were decomposed. The mechanical parameters assigned into the three-dimensional finite element model. The changes of displacement and stress in the model of lunbar pelvic and proximal femur under the four conditions were calculated with Abaqus model of Hypermesh 10. 1) Under the same condition,the displacement order of lumbar was L1>L2>L3>L5 L5, anterior column > middle column > posterior column. 2) Under the different conditions, the displacement order of lumbar,case 3>case 1>case 4>case 2. 3) Under the same conditions, the displacement order of lumbar inter-vertebral disc from L1,2 to L5S1 was L1,2>L2,3>L3,4>L4,5>L5S1, as for the same inter-vertebral disc, the order was: second quadrant>third quadrant>first quadrant>fourth quadrant. 4) Under the different conditions,the displacement order of the inter-vertebral disc was L1,2>L2,3>L3,4>L4,5>L5S1, but to same inter-vertebral disc: case 3>case 4>case 1 >case 2. 5) There were apparent displacement and stress concentration in pelvis and hip during the manipulation. 1) The principles of lumbar rotation manipulation closely related to the relative displacement caused by rotation of various parts of lumbar pelvic and proximal femur model; 2) During the process of lumbar rotatory manipulation, the angle of lateral bending and flexion can not be randomly increased; 3) During the process of lumbar rotatory manipulation, all the conditions of lumbar pelvic and proximal femur must be considered to determine indications and contraindications.

Multiple scattering in chiral media: border effects, reduced depolarization, and sensitivity limit

NASA Astrophysics Data System (ADS)

Delplancke, Francoise; Badoz, Jacques P.; Boccara, A. Claude

1997-10-01

Suspensions of polystyrene latex beads in chiral solutions were investigated. The rotatory power, induced by solubilized sucrose, in near-forward scattering was measured via a method using polarization modulation by photo-elastic modulator. The sensitivity of the measurement was enhanced and optimized in order to measure sucrose concentrations as low as 5 mg/ml in a cell 5 mm thick only. Different concentrations and diameters of latex particles were used in combination with different sucrose concentrations going from 1 mg/ml up to saturation. The experiments showed that the apparent rotatory power is enhanced by multiple scattering, that depolarization effects are less important with highly concentrated sucrose solutions and that attention has to be paid to cell border effects in order to avoid important artifacts, in case of highly scattering suspensions. Qualitative and theoretical explanations of those observations are presented. One possible application of this method is to measure the sugar content in human blood, in vivo, non-invasively, through the skin. The concentration to be evaluated is at the sensitivity limit. So any artifact has to be removed carefully, e.g. skin cell birefringence or chirality.

MEMS-based non-rotatory circumferential scanning optical probe for endoscopic optical coherence tomography

NASA Astrophysics Data System (ADS)

Xu, Yingshun; Singh, Janak; Siang, Teo Hui; Ramakrishna, Kotlanka; Premchandran, C. S.; Sheng, Chen Wei; Kuan, Chuah Tong; Chen, Nanguang; Olivo, Malini C.; Sheppard, Colin J. R.

2007-07-01

In this paper, we present a non-rotatory circumferential scanning optical probe integrated with a MEMS scanner for in vivo endoscopic optical coherence tomography (OCT). OCT is an emerging optical imaging technique that allows high resolution cross-sectional imaging of tissue microstructure. To extend its usage to endoscopic applications, a miniaturized optical probe based on Microelectromechanical Systems (MEMS) fabrication techniques is currently desired. A 3D electrothermally actuated micromirror realized using micromachining single crystal silicon (SCS) process highlights its very large angular deflection, about 45 degree, with low driving voltage for safety consideration. The micromirror is integrated with a GRIN lens into a waterproof package which is compatible with requirements for minimally invasive endoscopic procedures. To implement circumferential scanning substantially for diagnosis on certain pathological conditions, such as Barret's esophagus, the micromirror is mounted on 90 degree to optical axis of GRIN lens. 4 Bimorph actuators that are connected to the mirror on one end via supporting beams and springs are selected in this micromirror design. When actuators of the micromirror are driven by 4 channels of sinusoidal waveforms with 90 degree phase differences, beam focused by a GRIN is redirected out of the endoscope by 45 degree tilting mirror plate and achieve circumferential scanning pattern. This novel driving method making full use of very large angular deflection capability of our micromirror is totally different from previously developed or developing micromotor-like rotatory MEMS device for circumferential scanning.

Design of a Novel MEMS Microgripper with Rotatory Electrostatic Comb-Drive Actuators for Biomedical Applications.

PubMed

Velosa-Moncada, Luis A; Aguilera-Cortés, Luz Antonio; González-Palacios, Max A; Raskin, Jean-Pierre; Herrera-May, Agustin L

2018-05-22

Primary tumors of patients can release circulating tumor cells (CTCs) to flow inside of their blood. The CTCs have different mechanical properties in comparison with red and white blood cells, and their detection may be employed to study the efficiency of medical treatments against cancer. We present the design of a novel MEMS microgripper with rotatory electrostatic comb-drive actuators for mechanical properties characterization of cells. The microgripper has a compact structural configuration of four polysilicon layers and a simple performance that control the opening and closing displacements of the microgripper tips. The microgripper has a mobile arm, a fixed arm, two different actuators and two serpentine springs, which are designed based on the SUMMiT V surface micromachining process from Sandia National Laboratories. The proposed microgripper operates at its first rotational resonant frequency and its mobile arm has a controlled displacement of 40 µm at both opening and closing directions using dc and ac bias voltages. Analytical models are developed to predict the stiffness, damping forces and first torsional resonant frequency of the microgripper. In addition, finite element method (FEM) models are obtained to estimate the mechanical behavior of the microgripper. The results of the analytical models agree very well respect to FEM simulations. The microgripper has a first rotational resonant frequency of 463.8 Hz without gripped cell and it can operate up to with maximum dc and ac voltages of 23.4 V and 129.2 V, respectively. Based on the results of the analytical and FEM models about the performance of the proposed microgripper, it could be used as a dispositive for mechanical properties characterization of circulating tumor cells (CTCs).

Design of a Novel MEMS Microgripper with Rotatory Electrostatic Comb-Drive Actuators for Biomedical Applications

PubMed Central

Velosa-Moncada, Luis A.; Aguilera-Cortés, Luz Antonio; Raskin, Jean-Pierre

2018-01-01

Primary tumors of patients can release circulating tumor cells (CTCs) to flow inside of their blood. The CTCs have different mechanical properties in comparison with red and white blood cells, and their detection may be employed to study the efficiency of medical treatments against cancer. We present the design of a novel MEMS microgripper with rotatory electrostatic comb-drive actuators for mechanical properties characterization of cells. The microgripper has a compact structural configuration of four polysilicon layers and a simple performance that control the opening and closing displacements of the microgripper tips. The microgripper has a mobile arm, a fixed arm, two different actuators and two serpentine springs, which are designed based on the SUMMiT V surface micromachining process from Sandia National Laboratories. The proposed microgripper operates at its first rotational resonant frequency and its mobile arm has a controlled displacement of 40 µm at both opening and closing directions using dc and ac bias voltages. Analytical models are developed to predict the stiffness, damping forces and first torsional resonant frequency of the microgripper. In addition, finite element method (FEM) models are obtained to estimate the mechanical behavior of the microgripper. The results of the analytical models agree very well respect to FEM simulations. The microgripper has a first rotational resonant frequency of 463.8 Hz without gripped cell and it can operate up to with maximum dc and ac voltages of 23.4 V and 129.2 V, respectively. Based on the results of the analytical and FEM models about the performance of the proposed microgripper, it could be used as a dispositive for mechanical properties characterization of circulating tumor cells (CTCs). PMID:29789474

Treatment of atlantoaxial rotatory fixation with botulinum toxin muscle block and manipulation.

PubMed

Lin, Chia-Hung; Chen, Chun-Jung; Chen, Chuan-Mu; Liao, Su-Lan; Raung, Shue-Ling; Tsai, Sen-Wei

2010-04-01

Slippage after reduction of atlantoaxial rotatory fixation (AARF) is usually treated with repeated cervical traction and brace immobilization. To date, no data have been published on the management of muscle spasm during treatment. Here, we describe the case of a 7-year-old girl with AARF for 1 month who visited our hospital for treatment. During physical examination, spasm of the sternocleidomastoid muscle was noted. The patient was treated with manipulative reduction, and slippage after reduction was managed with botulinum spasticity block of the sternocleidomastoid and splenius capitis muscles, and repeated manipulation. Cervical orthosis immobilization with a rehabilitation program of isometric contract-relax exercise for the neck was conducted for 3 months. The subject had full recovery from AARF at 1-year follow-up. This report demonstrates that, in selected cases of slippage after reduction from AARF, conservative management with manipulation under anesthesia is a good method, and the muscle components may play a crucial role in AARF. Copyright 2010 Elsevier. Published by Elsevier B.V. All rights reserved.

Quantum optical rotatory dispersion

PubMed Central

Tischler, Nora; Krenn, Mario; Fickler, Robert; Vidal, Xavier; Zeilinger, Anton; Molina-Terriza, Gabriel

2016-01-01

The phenomenon of molecular optical activity manifests itself as the rotation of the plane of linear polarization when light passes through chiral media. Measurements of optical activity and its wavelength dependence, that is, optical rotatory dispersion, can reveal information about intricate properties of molecules, such as the three-dimensional arrangement of atoms comprising a molecule. Given a limited probe power, quantum metrology offers the possibility of outperforming classical measurements. This has particular appeal when samples may be damaged by high power, which is a potential concern for chiroptical studies. We present the first experiment in which multiwavelength polarization-entangled photon pairs are used to measure the optical activity and optical rotatory dispersion exhibited by a solution of chiral molecules. Our work paves the way for quantum-enhanced measurements of chirality, with potential applications in chemistry, biology, materials science, and the pharmaceutical industry. The scheme that we use for probing wavelength dependence not only allows one to surpass the information extracted per photon in a classical measurement but also can be used for more general differential measurements. PMID:27713928

Plasmodium falciparum: a simplified technique for obtaining singly infected erythrocytes.

PubMed

Puthia, Manoj K; Tan, Kevin S W

2005-02-01

We report the development of a simple technique involving 15 ml polypropylene tubes and a rotatory incubator for obtaining erythrocytes singly infected with Plasmodium falciparum. This technique will be useful for cloning of the parasite. Our finding that P. falciparum merozoite invasion is inhibited during rotation suggests that this method may also be useful for the study of parasite-erythrocyte interactions under dynamic circulatory conditions.

Long term results of surgery for non-acute anteromedial rotatory instability of the knee.

PubMed

Oretorp, N; Gillquist, J; Liljedahl, S O

1979-06-01

Seventy-eight patients treated by extraarticular reconstruction including pes anserinus transfer for anteromedial rotatory instability of the knee were reinvestigated 16--47 months (mean 28) after operation. Function before and after operation was assessed by means of a knee rating score. Of these patients, 94 per cent showed a higher score after operation. Twenty per cent showed full recovery with no limitation of knee function whatsoever. The follow-up score was higher with preserved medial meniscus function than when this structure had been removed. When not initially torn, the medial meniscus tended to become involved with time. Mild laxity in extension, possibly indicative of a posterior cruciate injury previously underestimated or not observed, was found in 15 per cent of the patients. No correlation was found between late knee function and the interval between injury and operation or the interval between operation and follow-up examination. The long term results were good. Extraarticular reconstruction is thus indicated in cases of chronic rotatory instability of the anteromedial type. Routine meniscectomy is not recommended in these patients, however. Signs possibly indicating posterior cruciate ligament involvement should be carefully looked for, as even minor posterior cruciate injury, easily overlooked, may influence the late results.

Longitudinal tear of the medial meniscus posterior horn in the anterior cruciate ligament-deficient knee significantly influences anterior stability.

PubMed

Ahn, Jin Hwan; Bae, Tae Soo; Kang, Ki-Ser; Kang, Soo Yong; Lee, Sang Hak

2011-10-01

Longitudinal tears of the medial meniscus posterior horn (MMPH) are commonly associated with a chronic anterior cruciate ligament (ACL) deficiency. Many studies have demonstrated the importance of the medial meniscus in terms of limiting the amount of anterior-posterior tibial translation in response to anterior tibial loads in ACL-deficient knees. An MMPH tear in an ACL-deficient knee increases the anterior-posterior tibial translation and rotatory instability. In addition, MMPH repair will restore the tibial translation to the level before the tear. Controlled laboratory study. Ten human cadaveric knees were tested sequentially using a custom testing system under 5 conditions: intact, ACL deficient, ACL deficient with an MMPH peripheral longitudinal tear, ACL deficient with an MMPH repair, and ACL deficient with a total medial meniscectomy. The knee kinematics were measured at 0°, 15°, 30°, 60°, and 90° of flexion in response to a 134-N anterior and 200-N axial compressive tibial load. The rotatory kinematics were also measured at 15° and 30° of flexion in a combined rotatory load of 5 N·m of internal tibial torque and 10 N·m of valgus torque. Medial meniscus posterior horn longitudinal tears in ACL-deficient knees resulted in a significant increase in anterior-posterior tibial translation at all flexion angles except 90° (P < .05). An MMPH repair in an ACL-deficient knee showed a significant decrease in anterior-posterior tibial translation at all flexion angles except 60° compared with the ACL-deficient/MMPH tear state (P < .05). The total anterior-posterior translation of the ACL-deficient/MMPH repaired knee was not significantly increased compared with the ACL (only)-deficient knee but was increased compared with the ACL-intact knee (P > .05). A total medial meniscectomy in an ACL-deficient knee did not increase the anterior-posterior tibial translation significantly compared with MMPH tears in ACL-deficient knees at all flexion angles (P > .05). In a combined rotatory load, tibial rotation after MMPH tears or a total medial meniscectomy in an ACL-deficient knee were not affected significantly at all flexion angles. This study shows that an MMPH longitudinal tear in an ACL-deficient knee alters the knee kinematics, particularly the anterior-posterior tibial translation. MMPH repair significantly improved anterior-posterior tibial translation in ACL-deficient knees. These findings may help improve the treatment of patients with ACL and MMPH longitudinal tear by suggesting that the medial meniscal repairs should be performed for greater longevity when combined with an ACL reconstruction.

Development of the Wake Behind a Circular Cylinder Impulsively Started into Rotatory and Rectilinear Motion: Intermediate Rotation Rates

DTIC Science & Technology

1991-01-01

cylindre fixe ou en rotation. Effet Magnus . J. Mec. 14, 109-134. Taneda, S. 1977 Visual study of unsteady separated flows around bodies. Prog. Aero...enhancement schemes employing the Magnus effect (Swanson 1961). Rotating all or part of a body may also have applications in active or feedback control of...and yt into the governing equations in the generalized coordinate system. In this study, the body-fitted grid is simply one of cylindrical polar

The Anterolateral Ligament: An Anatomic Study on Sex-Based Differences

PubMed Central

Daggett, Matt; Helito, Camilo; Cullen, Matthew; Ockuly, Andrew; Busch, Kyle; Granite, Joseph; Wright, Barth; Sonnery-Cottet, Bertrand

2017-01-01

Background: The anterolateral ligament (ALL) has been shown to have an important role in rotatory stability of the knee. While there is abundant research on sex-based differences related to anterior cruciate ligament (ACL) rupture, there is a paucity of literature related to such differences in the ALL. Purpose: To define any sex-based differences in the ALL with regard to length, width, and thickness. Study Design: Descriptive laboratory study. Methods: The ALL was initially evaluated in 165 unpaired knees (92 males and 65 females after exclusion criteria applied). The length, width, and thickness of the ALL were measured using a digital caliper. Width and thickness were measured at the joint line just superior to the lateral meniscus. The Mann-Whitney test and Student t tests were used to compare measurements between males and females. The Pearson product-moment correlation was subsequently used to determine the correlation between height and weight and the statistically different morphometric variables. Results: The mean (±SD) thickness of the ALL in males was 2.09 ± 0.56 mm, almost twice as thick as females (1.05 ± 0.49 mm; P = 8.8 × 10−20). There was also a statistically significant difference in ALL length (P = 3.8 × 10−7), but no significant difference was found for width. A moderate association was found between donor height and ALL thickness and length. Conclusion: The anatomic measurements of the ALL demonstrate a difference between sexes, and the ALL is significantly thicker in males than females. Clinical Relevance: As the role of the ALL in rotatory stability of the knee becomes better understood, the difference in the thickness of the ALL we have found between the sexes may be another factor why female athletes have an increased incidence of ACL rupture compared with males. This may also help explain why females have issues with knee laxity and rotatory instability. PMID:28321423

Rotatory and collic vestibular evoked myogenic potential testing in normal-hearing and hearing-impaired children.

PubMed

Maes, Leen; De Kegel, Alexandra; Van Waelvelde, Hilde; Dhooge, Ingeborg

2014-01-01

Vertigo and imbalance are often underestimated in the pediatric population, due to limited communication abilities, atypical symptoms, and relatively quick adaptation and compensation in children. Moreover, examination and interpretation of vestibular tests are very challenging, because of difficulties with cooperation and maintenance of alertness, and because of the sometimes nauseatic reactions. Therefore, it is of great importance for each vestibular laboratory to implement a child-friendly test protocol with age-appropriate normative data. Because of the often masked appearance of vestibular problems in young children, the vestibular organ should be routinely examined in high-risk pediatric groups, such as children with a hearing impairment. Purposes of the present study were (1) to determine age-appropriate normative data for two child-friendly vestibular laboratory techniques (rotatory and collic vestibular evoked myogenic potential [cVEMP] test) in a group of children without auditory or vestibular complaints, and (2) to examine vestibular function in a group of children presenting with bilateral hearing impairment. Forty-eight typically developing children (mean age 8 years 0 months; range: 4 years 1 month to 12 years 11 months) without any auditory or vestibular complaints as well as 39 children (mean age 7 years 8 months; range: 3 years 8 months to 12 years 10 months) with a bilateral sensorineural hearing loss were included in this study. All children underwent three sinusoidal rotations (0.01, 0.05, and 0.1 Hz at 50 degrees/s) and bilateral cVEMP testing. No significant age differences were found for the rotatory test, whereas a significant increase of N1 latency and a significant threshold decrease was noticeable for the cVEMP, resulting in age-appropriate normative data. Hearing-impaired children demonstrated significantly lower gain values at the 0.01 Hz rotation and a larger percentage of absent cVEMP responses compared with normal-hearing children. Seventy-four percent of hearing-impaired children showed some type of vestibular abnormality when examined with a combination of rotatory and cVEMP testing, in contrast to an abnormality rate of 60% with cVEMP and a rate of 49% with rotatory testing alone. The observed pediatric age correlations underscore the necessity of age-appropriate normative data to guarantee accurate interpretation of test results. The high percentages of abnormal vestibular test results in hearing-impaired children emphasize the importance of vestibular assessment in these children because the integrity of the vestibular system is a critical factor for motor and psychological development.

Development of the wake behind a circular cylinder impulsively started into rotatory and rectilinear motion

NASA Technical Reports Server (NTRS)

Chen, Yen-Ming; Ou, Yuh-Roung; Pearlstein, Arne J.

1993-01-01

The temporal development of a 2D viscous incompressible flow generated by a circular cylinder started impulsively into steady rotatory and rectilinear motion is studied by integration of a velocity/vorticity formulation of the governing equations, using an explicit finite-difference/pseudo-spectral technique and an implementation of the Biot-Savart law. Results are presented for a Reynolds number of 200 (based on the cylinder diameter 2a and the magnitude U of the rectilinear velocity) for several values of the angular/rectilinear speed ratio alpha = omega(a)/U (where omega is the angular speed) up to 3.25. Several aspects of the kinematics and dynamics of the flow not considered earlier are discussed. For higher values of alpha, the results indicate that for Re = 200, vortex shedding does indeed occur for alpha = 3.25. However, consecutive vortices shed by the body can be shed from the same side and be of the same sense, in contrast to the nonrotating case, in which mirror-image vortices of opposite sense are shed alternately on opposite sides of the body. The implications of the results are discussed in relation to the possibility of suppressing vortex shedding by open or closed-loop control of the rotation rate.

Effects of Spontaneous Locomotion on the Cricket's Walking Response to a Wind Stimulus

NASA Astrophysics Data System (ADS)

Gras, Heribert; Bartels, Anke

Tethered walking crickets often respond to single wind puffs (50ms duration) directed from 45° left or right to the abdominal cerci with a short running bout of about 300ms, followed by normal locomotion. To test for an effect of the current behavioral state on the running response, we applied wind stimuli when the insect attained a predefined translatorial and/or rotatorial velocity during spontaneous walking. The latency, duration, and velocity profile of the running bout always proved to be constant, representing a reflexlike all-or-nothing reaction, while the probability of this response was low after even brief standing and increased with the forward speed of spontaneous walking at the moment of stimulation. In contrast, the current rotatorial speed did not affect the stimulus response.

Vision preference in dynamic posturography analysed according to vestibular impairment and handicap.

PubMed

Perez, N I; Rama, J I; Martinez Vila, E

2004-01-01

The objective of this work was to characterise the implications of vision preference derived from the sensory organisation test of computerised dynamic posturography, in terms of impairment, disability and handicap. This was a prospective assessment of 88 patients suffering from dizziness who denied experiencing any visually induced vertiginous symptoms. The level of impairment of each patient was estimated by performing a complete analysis of vestibular function by means of the caloric and rotatory stimulation tests. Disability and handicap were determined with the Dizziness Handicap Inventory questionnaire (DHI). The results of the caloric test in patients were independent of vision preference although canal paresis was more frequently abnormal in patients without visual preference. No differences were found in the results of rotatory stimulation by means of impulse and sinusoidal tests, both at high velocities of stimuli, in between patients with and without vision preference. Similarly, the responses in the DHI, a common questionnaire for vestibular disability and handicap and, specifically to questions addressing the problem of visual and vestibular disability, were not able to differentiate either group of patients. Nevertheless, we have found that patients with vision preference tend to have poorer balance. We consider that in the patients studied here, vision preference must be considered as a normal finding as this represents a normal strategy in a subject that relies more heavily on visual cues for his or her postural control.

Development of the wake behind a circular cylinder impulsively started into rotatory and rectilinear motion: Intermediate rotation rates

NASA Technical Reports Server (NTRS)

Chen, Yen-Ming; Ou, Yuh-Roung; Pearlstein, Arne J.

1991-01-01

The temporal development of two-dimensional viscous incompressible flow generated by a circular cylinder started impulsively into steady rotatory and rectilinear motion is studied by integration of a velocity/vorticity formulation of the governing equations, using an explicit finite-difference/pseudo-spectral technique and an implementation of the Biot-Savart law. Results are presented for a Reynolds number of 200 (based on the cylinder diameter 2a and the magnitude U of the rectilinear velocity) for several values of the angular/rectilinear speed ratio alpha = (omega x a)/U (where omega is the angular speed) up to 3.25. Several aspects of the kinematics and dynamics of the flow not considered earlier are discussed. For higher values of alpha, the results indicate that for Re = 200, vortex shedding does indeed occur for alpha = 3.25. The shedding process is; however, very different from that which gives rise to the usual Karman vortex street for alpha = 0. In particular, consecutive vortices shed by the body can be shed from the same side and be of the same sense, in contrast to the nonrotating case, in which mirror-image vortices of opposite sense are shed alternately on opposite sides of the body. The implications of the results are discussed in relation to the possibility of suppressing vortex shedding by open or closed-loop control of the rotation rate.

Effectiveness of prolotherapy in the treatment of chronic rotator cuff lesions.

PubMed

Seven, M M; Ersen, O; Akpancar, S; Ozkan, H; Turkkan, S; Yıldız, Y; Koca, K

2017-05-01

Rotator cuff lesions are one of the major causes of shoulder pain and dysfunction. Numerous non-surgical treatment modalities have been described for chronic rotator cuff lesions, but the debate continues over the optimal procedure. The aim of this report is to present the results of prolotherapy in the treatment of chronic refractory rotator cuff lesions. Dextrose prolotherapy will reduce pain and improve shoulder function and patient satisfaction. We recruited 120 patients with chronic rotator cuff lesions and symptoms that persisted for longer than 6 months. Patients were divided into two groups: one treated with exercise (control group; n=60) and the other treated with prolotherapy injection (prolotherapy group; n=60). In the latter, ultrasound-guided prolotherapy injections were applied under aseptic conditions. In the former, patients received a physiotherapy protocol three sessions weekly for 12 weeks. Both groups were instructed to carry out a home exercise program. Clinical assessment of shoulder function was performed using a visual analog scale (VAS) for pain, Shoulder Pain and Disability Index (SPADI), Western Ontario Rotatory Cuff (WORC) Index, patient satisfaction, and shoulder range of motion. Patients were examined at baseline, weeks 3, 6, and 12, and last follow-up (minimum of one year). A total of 101 patients (44 controls and 57 in the prolotherapy group) completed all study protocols and were included in the study. Using a within-group comparison, both groups achieved significant improvements over baseline, as measured by the VAS, SPADI, WORC index, and shoulder range of motion (P<0.001). Using a between-group comparison, a significant difference was found in the VAS scores at baseline, weeks 3, 6, and 12, and last follow-up. In addition, significant differences were found in the SPADIs and WORC indices at weeks 6 and 12 and the last follow-up. Significant differences were found in shoulder abduction and flexion at week 12 and last follow-up, and in internal rotation at last follow-up. However, no significant was found in external rotation at any follow-up period. In the prolotherapy group, 53 patients (92.9%) reported excellent or good outcomes; in the control group, 25 patients (56.8%) reported excellent or good outcomes. Prolotherapy is an easily applicable and satisfying auxiliary method in the treatment of chronic rotatory cuff lesions. Randomized prospective comparative trial. Level of evidence 1. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Simulation of circularly polarized luminescence spectra using coupled cluster theory

NASA Astrophysics Data System (ADS)

McAlexander, Harley R.; Crawford, T. Daniel

2015-04-01

We report the first computations of circularly polarized luminescence (CPL) rotatory strengths at the equation-of-motion coupled cluster singles and doubles (EOM-CCSD) level of theory. Using a test set of eight chiral ketones, we compare both dipole and rotatory strengths for absorption (electronic circular dichroism) and emission to the results from time-dependent density-functional theory (TD-DFT) and available experimental data for both valence and Rydberg transitions. For two of the compounds, we obtained optimized geometries of the lowest several excited states using both EOM-CCSD and TD-DFT and determined that structures and EOM-CCSD transition properties obtained with each structure were sufficiently similar that TD-DFT optimizations were acceptable for the remaining test cases. Agreement between EOM-CCSD and the Becke three-parameter exchange function and Lee-Yang-Parr correlation functional (B3LYP) corrected using the Coulomb attenuating method (CAM-B3LYP) is typically good for most of the transitions, though agreement with the uncorrected B3LYP functional is significantly worse for all reported properties. The choice of length vs. velocity representation of the electric dipole operator has little impact on the EOM-CCSD transition strengths for nearly all of the states we examined. For a pair of closely related β, γ-enones, (1R)-7-methylenebicyclo[2.2.1]heptan-2-one and (1S)-2-methylenebicyclo[2.2.1]heptan-7-one, we find that EOM-CCSD and CAM-B3LYP agree with the energetic ordering of the two possible excited-state conformations, resulting in good agreement with experimental rotatory strengths in both absorption and emission, whereas B3LYP yields a qualitatively incorrect result for the CPL signal of (1S)-2-methylenebicyclo[2.2.1]heptan-7-one. Finally, we predict that one of the compounds considered here, trans-bicyclo[3.3.0]octane-3,7-dione, is unique in that it exhibits an achiral ground state and a chiral first excited state, leading to a strong CPL signal but a weak circular dichroism signal.

Simulation of circularly polarized luminescence spectra using coupled cluster theory

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

McAlexander, Harley R.; Crawford, T. Daniel, E-mail: crawdad@vt.edu

2015-04-21

We report the first computations of circularly polarized luminescence (CPL) rotatory strengths at the equation-of-motion coupled cluster singles and doubles (EOM-CCSD) level of theory. Using a test set of eight chiral ketones, we compare both dipole and rotatory strengths for absorption (electronic circular dichroism) and emission to the results from time-dependent density-functional theory (TD-DFT) and available experimental data for both valence and Rydberg transitions. For two of the compounds, we obtained optimized geometries of the lowest several excited states using both EOM-CCSD and TD-DFT and determined that structures and EOM-CCSD transition properties obtained with each structure were sufficiently similar thatmore » TD-DFT optimizations were acceptable for the remaining test cases. Agreement between EOM-CCSD and the Becke three-parameter exchange function and Lee-Yang-Parr correlation functional (B3LYP) corrected using the Coulomb attenuating method (CAM-B3LYP) is typically good for most of the transitions, though agreement with the uncorrected B3LYP functional is significantly worse for all reported properties. The choice of length vs. velocity representation of the electric dipole operator has little impact on the EOM-CCSD transition strengths for nearly all of the states we examined. For a pair of closely related β, γ-enones, (1R)-7-methylenebicyclo[2.2.1]heptan-2-one and (1S)-2-methylenebicyclo[2.2.1]heptan-7-one, we find that EOM-CCSD and CAM-B3LYP agree with the energetic ordering of the two possible excited-state conformations, resulting in good agreement with experimental rotatory strengths in both absorption and emission, whereas B3LYP yields a qualitatively incorrect result for the CPL signal of (1S)-2-methylenebicyclo[2.2.1]heptan-7-one. Finally, we predict that one of the compounds considered here, trans-bicyclo[3.3.0]octane-3,7-dione, is unique in that it exhibits an achiral ground state and a chiral first excited state, leading to a strong CPL signal but a weak circular dichroism signal.« less

Quantitative structure-retention relationship studies with immobilized artificial membrane chromatography II: partial least squares regression.

PubMed

Li, Jie; Sun, Jin; He, Zhonggui

2007-01-26

We aimed to establish quantitative structure-retention relationship (QSRR) with immobilized artificial membrane (IAM) chromatography using easily understood and obtained physicochemical molecular descriptors and to elucidate which descriptors are critical to affect the interaction process between solutes and immobilized phospholipid membranes. The retention indices (logk(IAM)) of 55 structurally diverse drugs were determined on an immobilized artificial membrane column (IAM.PC.DD2) directly or obtained by extrapolation method for highly hydrophobic compounds. Ten simple physicochemical property descriptors (clogP, rings, rotatory bond, hydro-bond counting, etc.) of these drugs were collected and used to establish QSRR and predict the retention data by partial least squares regression (PLSR). Five descriptors, clogP, rotatory bond (RotB), rings, molecular weight (MW) and total surface area (TSA), were reserved by using the Variable Importance for Projection (VIP) values as criterion to build the final PLSR model. An external test set was employed to verify the QSRR based on the training set with the five variables, and QSRR by PLSR exhibited a satisfying predictive ability with R(p)=0.902 and RMSE(p)=0.400. Comparison of coefficients of centered and scaled variables by PLSR demonstrated that, for the descriptors studied, clogP and TSA have the most significant positive effect but the rotatable bond has significant negative effect on drug IAM chromatographic retention.

Biomechanical Reconstruction Using the Tacit Learning System: Intuitive Control of Prosthetic Hand Rotation.

PubMed

Oyama, Shintaro; Shimoda, Shingo; Alnajjar, Fady S K; Iwatsuki, Katsuyuki; Hoshiyama, Minoru; Tanaka, Hirotaka; Hirata, Hitoshi

2016-01-01

Background: For mechanically reconstructing human biomechanical function, intuitive proportional control, and robustness to unexpected situations are required. Particularly, creating a functional hand prosthesis is a typical challenge in the reconstruction of lost biomechanical function. Nevertheless, currently available control algorithms are in the development phase. The most advanced algorithms for controlling multifunctional prosthesis are machine learning and pattern recognition of myoelectric signals. Despite the increase in computational speed, these methods cannot avoid the requirement of user consciousness and classified separation errors. "Tacit Learning System" is a simple but novel adaptive control strategy that can self-adapt its posture to environment changes. We introduced the strategy in the prosthesis rotation control to achieve compensatory reduction, as well as evaluated the system and its effects on the user. Methods: We conducted a non-randomized study involving eight prosthesis users to perform a bar relocation task with/without Tacit Learning System support. Hand piece and body motions were recorded continuously with goniometers, videos, and a motion-capture system. Findings: Reduction in the participants' upper extremity rotatory compensation motion was monitored during the relocation task in all participants. The estimated profile of total body energy consumption improved in five out of six participants. Interpretation: Our system rapidly accomplished nearly natural motion without unexpected errors. The Tacit Learning System not only adapts human motions but also enhances the human ability to adapt to the system quickly, while the system amplifies compensation generated by the residual limb. The concept can be extended to various situations for reconstructing lost functions that can be compensated.

Coaxial rotatory-freestanding triboelectric nanogenerator for effective energy scavenging from wind

NASA Astrophysics Data System (ADS)

Ren, Xiaohu; Fan, Huiqing; Wang, Chao; Ma, Jiangwei; Zhao, Nan

2018-06-01

Ambient mechanical energy is one of the most abundant energy sources around us. It is a promising approach to solve the problem of energy and environment by harvesting such energy due to its cost-effectiveness, environmental friendliness and sustainability. Recently, triboelectric nanogenerator (TENG) has been proposed as an effective and promising technology for harvesting ambient mechanical energy. Herein, a coaxial rotatory-freestanding TENG (CRF-TENG) was developed and its theoretical model was constructed. An approximate V–Q–α relationship was derived and the explicit analytical solutions of the transferred charge, output current, voltage and average power are obtained from numerically calculation. Finally, to verify the theoretical results, the real output performances of as-fabricated CRF-TENG were measured. The experimental results are consistent with the theoretical ones. The newly developed TENG mode greatly expands the applicability of TENGs for harvesting energy from ambient rotating mechanical motion.

Translabyrinthine surgery for disabling vertigo in vestibular schwannoma patients.

PubMed

Godefroy, W P; Hastan, D; van der Mey, A G L

2007-06-01

To determine the impact of translabyrinthine surgery on the quality of life in vestibular schwannoma patients with rotatory vertigo. Prospective study in 18 vestibular schwannoma patients. The study was conducted in a multispecialty tertiary care clinic. All 18 patients had a unilateral intracanalicular vestibular schwannoma, without serviceable hearing in the affected ear and severely handicapped by attacks of rotatory vertigo and constant dizziness. Despite an initial conservative treatment, extensive vestibular rehabilitation exercises, translabyrinthine surgery was performed because of the disabling character of the vertigo, which considerably continued to affect the patients' quality of life. Preoperative and postoperative quality of life using the Short Form 36 Health Survey (Short Form-36) scores and Dizziness Handicap Inventory (DHI) scores. A total of 17 patients (94%) completed the questionnaire preoperatively and 3 and 12 months postoperatively. All Short Form-36 scales of the studied patients scored significantly lower when compared with the healthy Dutch control sample (P < 0.05). There was a significant improvement of DHI total scores and Short Form-36 scales on physical and social functioning, role-physical functioning, role-emotional functioning, mental health and general health at 12 months after surgery when compared with preoperative scores (P < 0.05). Vestibular schwannoma patients with disabling vertigo, experience significant reduced quality of life when compared with a healthy Dutch population. Translabyrinthine tumour removal significantly improved the patients' quality of life. Surgical treatment should be considered in patients with small- or medium-sized tumours and persisting disabling vertigo resulting in a poor quality of life.

A Single Chiroptical Spectroscopic Method May Not Be Able To Establish the Absolute Configurations of Diastereomers: Dimethylesters of Hibiscus and Garcinia Acids

PubMed Central

Polavarapu, Prasad L.; Donahue, Emily A.; Shanmugam, Ganesh; Scalmani, Giovanni; Hawkins, Edward K.; Rizzo, Carmelo; Ibnusaud, Ibrahim; Thomas, Grace; Habel, Deenamma; Sebastian, Dellamol

2013-01-01

Electronic circular dichroism (ECD), optical rotatory dispersion (ORD), and vibrational circular dichroism (VCD) spectra of hibiscus acid dimethyl ester have been measured and analyzed in combination with quantum chemical calculations of corresponding spectra. These results, along with those reported previously for garcinia acid dimethyl ester, reveal that none of these three (ECD, ORD, or VCD) spectroscopic methods, in isolation, can unequivocally establish the absolute configurations of diastereomers. This deficiency is eliminated when a combined spectral analysis of either ECD and VCD or ORD and VCD methods is used. It is also found that the ambiguities in the assignment of absolute configurations of diastereomers may also be overcome when unpolarized vibrational absorption is included in the spectral analysis. PMID:21568330

High-grade rotatory knee laxity may be predictable in ACL injuries.

PubMed

Musahl, Volker; Burnham, Jeremy; Lian, Jayson; Popchak, Adam; Svantesson, Eleonor; Kuroda, Ryosuke; Zaffagnini, Stefano; Samuelsson, Kristian

2018-06-21

Lateral compartment acceleration and translation have been used to quantify rotatory knee laxity in the setting of anterior cruciate ligament (ACL) injury; however, their relationship remains elusive. The purpose of this study was to examine the correlation between lateral compartment acceleration and translation during pivot shift testing. It was hypothesized that a correlation would exist in ACL-injured and uninjured knees, irrespective of sex, but would be greatest in knees with combined ACL and lateral meniscus tear. Seventy-seven patients (34 females, 25.2 ± 9.0 years) undergoing primary single-bundle ACL reconstruction were prospectively enrolled in a 2-year study across four international centers. Patients underwent preoperative examination under anesthesia of the injured and uninjured knee using Image Analysis software and surface mounted accelerometer. A moderate correlation between lateral compartment acceleration and translation was observed in ACL-injured knees [ρ = 0.36, p < 0.05), but not in uninjured knees (ρ = 0.17, not significant (n.s.)]. A moderate correlation between acceleration and translation was demonstrated in ACL-injured knees with lateral meniscus tears (ρ = 0.53, p < 0.05), but not in knees with isolated ACL-injury (ρ = 0.32, n.s.), ACL and medial meniscus tears (ρ = 0.14, n.s.), or ACL and combined medial and lateral meniscus tears (ρ = 0.40, n.s.). A moderate correlation between acceleration and translation was seen in males (ρ = 0.51, p < 0.05), but not in females (ρ = 0.21, n.s.). Largest correlations were observed in males with ACL and lateral meniscus tears (ρ = 0.75, p < 0.05). Lateral compartment acceleration and translation were moderately correlated in ACL-injured knees, but largely correlated in males with combined ACL and lateral meniscus tears. ACL and lateral meniscus injury in males might, therefore, be suspected when both lateral compartment acceleration and translation are elevated. Surgeons should have a greater degree of suspicion for high-grade rotatory knee laxity in ACL-injured males with concomitant lateral meniscus tears. Future studies should investigate how these two distinct components of rotatory knee laxity-lateral compartment acceleration and translation-are correlated with patient outcomes and affected by ACL surgery. Prospective cohort study; Level of evidence II.

Simultaneous Reconstruction of the Anterior Cruciate Ligament and Medial Collateral Ligament in Patients With Chronic ACL-MCL Lesions: A Minimum 2-Year Follow-up Study.

PubMed

Zhang, Hangzhou; Sun, Yu; Han, Xiaorui; Wang, Yanfeng; Wang, Lin; Alquhali, Ali; Bai, Xizhuang

2014-07-01

In cases of chronic anterior cruciate ligament (ACL)-medial collateral ligament (MCL) lesions, nonoperative treatment of the MCL lesion may lead to chronic valgus instability and rotatory instability. The optimal management for patients who have combined ACL-MCL injuries remains controversial. To present a case series of 21 patients who underwent simultaneous ACL-MCL reconstruction with a 2- to 5-year follow-up. Case series; Level of evidence, 4. From October 2007 to December 2010, a total of 21 patients with chronic ACL-MCL injuries, for which the 2 ligaments were reconstructed during the same surgical procedure, were studied. All patients were available for follow-up for at least 2 years. The International Knee Documentation Committee (IKDC) subjective knee scores, valgus and sagittal stability, anteromedial rotatory stability, range of motion, and complications were assessed both preoperatively and postoperatively. At follow-up, valgus and sagittal laxity were not observed in any of the patients. The mean medial knee opening was significantly reduced to 0.80 ± 0.96 mm (range, -1.2 to 2.6 mm) postoperatively compared with 8.0 ± 1.3 mm (range, 6.1 to 10.7 mm) preoperatively (P < .01). The mean postoperative side-to-side difference measured with the KT-1000 arthrometer was reduced to 0.8 ± 0.9 mm (range, -1.2 to 2.3 mm) compared with 8.4 ± 1.6 mm (range, 6.2 to 13.2 mm) preoperatively (P < .01). Preoperative anteromedial instability was seen in 71% of patients (15/21), whereas none of the patients had anteromedial rotatory instability at the last follow-up. The mean IKDC subjective score improved overall from 45.3 ± 12.0 (range, 28.7-69.0) preoperatively to 87.7 ± 8.2 (range, 65.5-100.0) at the last follow-up (P < .01). Most patients (20/21) had normal or nearly normal range of motion of the knee joint; only 1 patient (5%) had a limitation of flexion of 15° compared with the contralateral knee at the last follow-up. In patients with chronic ACL-MCL lesions, simultaneous reconstruction of the ACL and MCL can significantly improve the medial, sagittal, and rotatory stability of the knee at short-term follow-up. © 2014 The Author(s).

Cervical Rotatory Manipulation Decreases Uniaxial Tensile Properties of Rabbit Atherosclerotic Internal Carotid Artery

PubMed Central

Qi, Ji; Zhang, Lei; Chen, Chao; Mondal, Shubhro; Ping, Kaike; Chen, Yili

2017-01-01

Objective. To investigate the effects of one of the Chinese massage therapies, cervical rotatory manipulation (CRM), on uniaxial tensile properties of rabbit atherosclerotic internal carotid artery (ICA). Methods. 40 male purebred New Zealand white rabbits were randomly divided into CRM-Model group, Non-CRM-Model group, CRM-Normal group, and Non-CRM-Normal group. After modeling (atherosclerotic model) and intervention (CRM or Non-CRM), uniaxial tensile tests were performed on the ICAs to assess the differences in tensile mechanical properties between the four groups. Results. Both CRM and modeling were the main effects affecting physiological elastic modulus (PEM) of ICA. PEM in CRM-Model group was 1.81 times as much as Non-CRM-Model group, while the value in CRM-Model group was 1.34 times as much as CRM-Normal group. Maximum elastic modulus in CRM-Model group was 1.80 times as much as CRM-Normal group. Max strains in CRM-Model group and Non-CRM-Model group were 30.98% and 28.71% lower than CRM-Normal group and Non-CRM-Normal group, respectively. However, whether treated with CRM or not, the uniaxial tensile properties of healthy ICAs were not statistically different. Conclusion. CRM may decrease the uniaxial tensile properties of rabbit arteriosclerotic ICA, but with no effect on normal group. The study will aid in the meaningful explanation of the controversy about the harmfulness of CRM and the suitable population of CRM. PMID:28303160

Knee arthrodesis using a vascularized fibular rotatory graft after tumor resection.

PubMed

Nouri, H; Meherzi, M H; Jenzeri, M; Daghfous, M; Hdidane, R; Zehi, K; Tarhouni, L; Karray, S; Baccari, S; Mestiri, M; Zouari, M

2010-02-01

Knee arthrodesis is one of the reconstruction options for limb preservation after malignant tumor resection. Vascularised rotatory fibular transfer allows biological and, thus,definitive reconstruction. The goal of this work was to analyse the results of knee arthrodesis with vascularised fibular graft after tumor resection and to discuss the reliability of this technique. We report a retrospective series of 13 patients with an average age of 29.6 years. The pathological diagnosis was bone sarcoma in 12 cases and synovial chondrosarcoma in one case. Resection/arthrodesis was undertaken as the primary procedure in 11 cases.In two cases, arthrodesis was indicated after failure of an endoprosthesis. Reconstruction was achieved with a vascularised fibular rotatory transfer in all cases. For stabilisation, an external fixator was utilised in eight cases, a femorotibial nail in three cases, and a plate in two cases.Mean follow-up was 6 years. We encountered infection in 53% of cases, mechanical complications in 53% of cases,and nerve palsy in 23% of cases. Four patients died from metastases (only one had arthrodesis complete union). In the nine surviving patients, arthrodesis was fully united in seven cases,after an average period of 36 months. The functional score average (Enneking classification)was 20 points. Knee arthrodesis after tumor resection is a complex technique. Septic complications and mechanical failure are frequent regardless of the technique employed. They are related to the extent of bone sacrifice but also to that of soft tissues. The use of vascularised fibula alone and stabilisation by external fixation were the main shortcomings in this series. TYPE OF STUDY RETROSPECTIVE: Level IV. 2009 Published by Elsevier Masson SAS.

Ab initio study of excited state electronic circular dichroism. Two prototype cases: methyl oxirane and R-(+)-1,1'-bi(2-naphthol).

PubMed

Rizzo, Antonio; Vahtras, Olav

2011-06-28

A computational approach to the calculation of excited state electronic circular dichroism (ESECD) spectra of chiral molecules is discussed. Frequency dependent quadratic response theory is employed to compute the rotatory strength for transitions between excited electronic states, by employing both a magnetic gauge dependent and a (velocity-based) magnetic gauge independent approach. Application is made to the lowest excited states of two prototypical chiral molecules, propylene oxide, also known as 1,2-epoxypropane or methyl oxirane, and R-(+)-1,1'-bi(2-naphthol), or BINOL. The dependence of the rotatory strength for transitions between the lowest three excited states of methyl oxirane upon the quality and extension of the basis set is analyzed, by employing a hierarchy of correlation consistent basis sets. Once established that basis sets of at least triple zeta quality, and at least doubly augmented, are sufficient to ensure sufficiently converged results, at least at the Hartree-Fock self-consistent field (HF-SCF) level, the rotatory strengths for all transitions between the lowest excited electronic states of methyl oxirane are computed and analyzed, employing HF-SCF, and density functional theory (DFT) electronic structure models. For DFT, both the popular B3LYP and its recently highly successful CAM-B3LYP extension are exploited. The strong dependence of the spectra upon electron correlation is highlighted. A HF-SCF and DFT study is carried out also for BINOL, a system where excited states show the typical pairing structure arising from the interaction of the two monomeric moieties, and whose conformational changes following photoexcitation were studied recently with via time-resolved CD.

Tri-p-tolyl­phosphine

PubMed Central

Wang, Hao; Wang, Yi-Bin; Liu, Bo-Nian; Tang, Shi-Gui; Wei, Ping

2008-01-01

In the title compound C21H21P, the P atom is situated on a crystallographic threefold rotatory-inversion axis, resulting in threefold rotation symmetry of the title compound. The dihedral angles between the symmetry-related benzene rings are 87.40 (18)°. PMID:21201763

Raman spectroscopy of garnet-group minerals

USGS Publications Warehouse

Mingsheng, P.; Mao, Ho-kwang; Dien, L.; Chao, E.C.T.

1994-01-01

The Raman spectra of the natural end members of the garnet-group minerals, which include pyrope, almandine and spessarite of Fe-Al garnet series and grossularite, andradite and uvarovite of Ca-Fe garnet series, have been studied. Measured Raman spectra of these minerals are reasonably and qualitatively assigned to the internal modes, translational and rotatory modes of SiO4 tetrahedra, as well as the translational motion of bivalent cations in the X site. The stretch and rotatory Alg modes for the Fe-Al garnet series show obvious Raman shifts as compared with those for the Ca-Fe garnet series, owing to the cations residing in the X site connected with SiO4 tetrahedra by sharing the two edges. The Raman shifts of all members within either of the series are attributed mainly to the properties of cations in the X site for the Fe-Al garnet series and in the Y site for the Ca-Fe garnet series. ?? 1994 Institute of Geochemistry, Chinese Academy of Sciences.

Orientation relationship between the T structure and the icosahedral quasicrystal in the Zn-Mg-Al alloy system

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

Nakayama, Kei, E-mail: k.n@aoni.waseda.jp; Watanabe, Junya; Koyama, Yasumasa, E-mail: ykoyama@waseda.jp

2016-08-26

To understand the crystallographic relation between the Bergman-type icosahedral quasicrystal and its approximant-T structure, we have investigated the crystallographic features of prepared Zn-Mg-Al alloy samples, mainly by transmission electron microscopy. It was found that there existed three kinds of regions: that is, C14-Laves, approximant-T, and icosahedral-quasicrystal regions, in Zn-Mg-Al alloy samples with the composition of Zn-36at.%Mg-9at.%Al. Among these regions, in particular, we tried to determine an orientation relationship between neighboring icosahedral-quasicrystal and approximant-T regions. Based on the determined relationship, for instance, four threefold rotatory-inversion axes in the T structure were found to be parallel to four of ten threefold rotatory-inversionmore » axes in the icosahedral quasicrystal. It was thus understood that the atomic arrangements of the Bergman-type icosahedral quasicrystal and its approximant-T structure are likely to resemble each other.« less

What does it take to have a high-grade pivot shift?

PubMed

Tanaka, M; Vyas, D; Moloney, G; Bedi, A; Pearle, A D; Musahl, V

2012-04-01

The pivot shift is the most specific clinical test to assess pathological knee joint rotatory laxity following ACL injury. This article attempts to describe the anatomic structures responsible for creating a high-grade pivot shift and their potential role in customizing ACL reconstruction. A review of the literature demonstrates that disruption of the secondary stabilizers of anterior translation of the lateral compartment including the lateral meniscus, anterolateral capsule, and IT band contributes to a high-grade pivot shift in the ACL-deficient knee. The morphology of the lateral tibial plateau, including increased posteroinferior tibial slope and small size, can also contribute to high-grade pivot shift. Factors that may decrease the grade of the pivot shift include medial compartment injury, MCL injury, patient guarding, and osteoarthritis. In conclusion, a high-grade pivot shift in the ACL-deficient knee is often associated with incompetence of the lateral soft tissue envelope. Rotatory laxity as assessed by the pivot shift may also be falsely underestimated by concomitant injuries. IV.

Bragg reflection band width and optical rotatory dispersion of cubic blue-phase liquid crystals

NASA Astrophysics Data System (ADS)

Yoshida, Hiroyuki; Anucha, Konkanok; Ogawa, Yasuhiro; Kawata, Yuto; Ozaki, Masanori; Fukuda, Jun-ichi; Kikuchi, Hirotsugu

2016-10-01

The Bragg reflection band width and optical rotatory dispersion of liquid crystalline cholesteric blue phases (BPs) I and II are compared by numerical simulations. Attention is paid to the wavelength regions for which the reflection bands with lowest photon energies appear, i.e., the [110 ] direction for BP I and the [100 ] direction for BP II. Finite difference time domain and 4 ×4 matrix calculations performed on the theoretical director tensor distribution of BPs with the same material parameters show that BP II, which has simple cubic symmetry, has a wider photonic band gap than BP I, which has body centered cubic symmetry, possibly due to the fact that the density of the double-twist cylinders in BP II are twice that in BP I. The theoretical results on the Bragg reflection band width are supported by reflectance measurements performed on BPs I and II for light incident along the [110 ] and [100 ] directions, respectively.

Piezosurgery or conventional rotatory instruments for inferior third molar extractions?

PubMed

Piersanti, Luigi; Dilorenzo, Matteo; Monaco, Giuseppe; Marchetti, Claudio

2014-09-01

The purpose of this study was to compare the discomfort and surgical outcomes of a piezosurgery device with those of rotatory instruments in lower third molar extraction. A split-mouth, randomized, unblinded clinical study was designed; the 2 molars had to have the same extraction difficulty score. The test side was extracted using a piezosurgery technique and the control side was extracted using a conventional handpiece. The primary endpoint was patient discomfort evaluated with the Postoperative Symptom Severity (PoSSe) scale, which was administered to each patient; secondary endpoints were pain, trismus, swelling, and surgical time evaluation. Paired-samples t test and repeated-measures analysis of variance were used to compare outcomes within patients. Ten consecutive patients (6 female, 4 male; mean age, 22.4 ± 2.3 yr) were recruited. The total score on the PoSSe scale was significantly lower for piezosurgery compared with the conventional rotating handpiece (24.7 ± 10.3 vs 36.0 ± 7.6; t = -4.27; P = .002). Moreover, postoperative swelling 1 week after surgery was significantly lower for piezosurgery than for the conventional rotating handpiece (2.75 ± 0.23 vs 3.1 ± 0.39 cm; t = -2.63; P = .027). Piezosurgery was associated with less postoperative discomfort and yielded better results for swelling. Piezosurgery seems to be a good technique in daily surgical practice, especially if applied in the critical steps in which safety and respect for soft tissue, bone, and nerves are necessary. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Cotton Effect in Copper-Proline Complexes in the Visible Region

ERIC Educational Resources Information Center

Volkov, Victor; Pfister, Rolf

2005-01-01

The electronic properties of Cu(II) complex with proline are considered to demonstrate the Cotton effect in the visible region. A series of experiments in optical rotatory dispersion spectroscopy with free D- and L-proline and their complexes with the Cu(II) ion in aqueous solution is suggested.

Solvent, temperature and concentration effects on the optical rotatory dispersion of (R)-3-methylcyclohexanone

NASA Astrophysics Data System (ADS)

Alenaizan, Asem; Al-Basheer, Watheq; Musa, Musa M.

2017-02-01

Optical rotatory dispersion (ORD) spectra are reported for isolated and solvated (R)-3-methylcyclohexanone (R-3MCH) in 10 solvents, of wide polarity range, and over the spectral range 350-650 nm. Sample concentration effects on ORD spectra of R-3MCH were also recorded and investigated over widely varying concentrations from 2.5 × 10-3 to 2.5 × 10-1 g/mL where an observed sensitivity of optical rotation (OR) to incident light wavelength at low concentrations is correlated to solvent effects. Temperature effects were also studied by recording ORD spectra over the temperature range 0-65 °C in toluene. Recorded specific OR was plotted against various solvent parameters, namely, dipole moment, polarity, refractive index and polarizability to probe solvent effects. Furthermore, solvent effects were studied by incorporating Kamlet's and Taft's solvent parameters in the multi-parametric linear fitting. Theoretically, ORD spectra and populations of optimized geometries of equatorial and axial conformers of R-3MCH were calculated in the gas and solvated phases. All theoretical calculations were performed employing the polarizable continuum model using density functional theoretical and composite scheme (G4) methods with aug-cc-pVTZ and aug-cc-pVDZ basis sets. Net ORD spectra of R-3MCH were generated by the Boltzmann-weighted sum of the contributions of the dominant conformers. Upon comparing theoretical and experimental ORD spectra, a very good agreement is observed for the ORD spectra in the gas phase and high polarity solvents compared to relatively lesser agreement in low polarity solvents.

A study of the chiro-optical properties of Carvone

NASA Astrophysics Data System (ADS)

Lambert, Jason

2011-10-01

The intrinsic optical rotatory dispersion (IORD) and circular dichroism (CD) of the conformationally flexible carvone molecule has been investigated in 17 solvents and compared with results from calculations for the ``free'' (gas phase) molecule. The G3 method was used to determine the relative energies of the six conformers. The ORD of (R)-(-)-carvone at 589 nm was calculated using coupled cluster and density-functional methods, including temperature-dependent vibrational corrections. Vibrational corrections are significant and are primarily associated with normal modes involving the stereogenic carbon atom and the carbonyl group, whose n->&*circ; excitation plays a significant role in the chiroptical response of carvone. However, without the vibrational correction the calculated ORD is of opposite sign to that of the experiment for the CCSD and B3LYP methods. Calculations performed in solution using the PCM model were also opposite in sign to of the experiment when using the B3LYP density functional.

Bilateral and multiple cavitation sounds during upper cervical thrust manipulation

PubMed Central

2013-01-01

Background The popping produced during high-velocity, low-amplitude (HVLA) thrust manipulation is a common sound; however to our knowledge, no study has previously investigated the location of cavitation sounds during manipulation of the upper cervical spine. The primary purpose was to determine which side of the spine cavitates during C1-2 rotatory HVLA thrust manipulation. Secondary aims were to calculate the average number of pops, the duration of upper cervical thrust manipulation, and the duration of a single cavitation. Methods Nineteen asymptomatic participants received two upper cervical thrust manipulations targeting the right and left C1-2 articulation, respectively. Skin mounted microphones were secured bilaterally over the transverse process of C1, and sound wave signals were recorded. Identification of the side, duration, and number of popping sounds were determined by simultaneous analysis of spectrograms with audio feedback using custom software developed in Matlab. Results Bilateral popping sounds were detected in 34 (91.9%) of 37 manipulations while unilateral popping sounds were detected in just 3 (8.1%) manipulations; that is, cavitation was significantly (P < 0.001) more likely to occur bilaterally than unilaterally. Of the 132 total cavitations, 72 occurred ipsilateral and 60 occurred contralateral to the targeted C1-2 articulation. In other words, cavitation was no more likely to occur on the ipsilateral than the contralateral side (P = 0.294). The mean number of pops per C1-2 rotatory HVLA thrust manipulation was 3.57 (95% CI: 3.19, 3.94) and the mean number of pops per subject following both right and left C1-2 thrust manipulations was 6.95 (95% CI: 6.11, 7.79). The mean duration of a single audible pop was 5.66 ms (95% CI: 5.36, 5.96) and the mean duration of a single manipulation was 96.95 ms (95% CI: 57.20, 136.71). Conclusions Cavitation was significantly more likely to occur bilaterally than unilaterally during upper cervical HVLA thrust manipulation. Most subjects produced 3–4 pops during a single rotatory HVLA thrust manipulation targeting the right or left C1-2 articulation; therefore, practitioners of spinal manipulative therapy should expect multiple popping sounds when performing upper cervical thrust manipulation to the atlanto-axial joint. Furthermore, the traditional manual therapy approach of targeting a single ipsilateral or contralateral facet joint in the upper cervical spine may not be realistic. PMID:23320608

Planar reorientation of a free-free beam in space using embedded electromechanical actuators

NASA Technical Reports Server (NTRS)

Kolmanovsky, Ilya V.; Mcclamroch, N. Harris

1993-01-01

It is demonstrated that the planar reorientation of a free-free beam in zero gravity space can be accomplished by periodically changing the shape of the beam using embedded electromechanical actuators. The dynamics which determine the shape of the free-free beam is assumed to be characterized by the Euler-Bernoulli equation, including material damping, with appropriate boundary conditions. The coupling between the rigid body motion and the flexible motion is explained using the angular momentum expression which includes rotatory inertia and kinematically exact effects. A control scheme is proposed where the embedded actuators excite the flexible motion of the beam so that it rotates in the desired sense with respect to a fixed inertial reference. Relations are derived which relate the average rotation rate to the amplitudes and the frequencies of the periodic actuation signal and the properties of the beam. These reorientation maneuvers can be implemented by using feedback control.

Alcohol and disorientation-related responses. V, The influence of alcohol on positional, rotatory, and coriolis vestibular responses over 32-hour periods.

DOT National Transportation Integrated Search

1971-10-01

There are some indications that the systems most closely associated with disorientation responses--the visual and vestibular systems--may continue to show effects of alcohol ingestion for periods in excess of 24 hours. These effects may be evident bo...

New design for a rotatory joint actuator made with shape memory alloy contractile wire

NASA Astrophysics Data System (ADS)

Wang, Guoping; Shahinpoor, Mohsen

1996-05-01

A design approach for a rotatory joint actuator using a contractile shape memory alloy (SMA) wire is presented and an example design is followed. In this example, the output torque of the actuator is 18 Newton-meters, and its angular range is 30 degrees. Compared with a SMA spring type actuating component, a SMA wire type actuating component uses less SMA material and uses less electrical energy when it is electrically powered. On the other hand, a SMA wire type actuating component must have a large SMA wire length to produce a required amount of angular rotation of the joint. When pulleys are used to arrange a lengthy SMA wire in a small space, the friction between pulleys and pins is introduced and the performance of the joint actuator is degenerated to some degree. The investigated joint actuator provides a good chance for developing powered orthoses with SMA actuators for disabled individuals. It can relieve the weight concern with hydraulic and motor-powered orthoses and the safety concern with motor-powered orthoses. When electrically powered, a SMA actuator has the disadvantage of low energy efficiency.

Compressible Analysis of Bénard Convection of Magneto Rotatory Couple-Stress Fluid

NASA Astrophysics Data System (ADS)

Mehta, C. B.; Singh, M.

2018-02-01

Thermal Instability (Benard's Convection) in the presence of uniform rotation and uniform magnetic field (separately) is studied. Using the linearized stability theory and normal mode analyses the dispersion relation is obtained in each case. In the case of rotatory Benard's stationary convection compressibility and rotation postpone the onset of convection whereas the couple-stress have duel character onset of convection depending on rotation parameter. While in the absence of rotation couple-stress always postpones the onset of convection. On the other hand, magnetic field on thermal instability problem on couple-stress fluid for stationary convection couple-stress parameter and magnetic field postpones the onset of convection. The effect of compressibility also postpones the onset of convection in both cases as rotation and magnetic field. Graphs have been plotted by giving numerical values to the parameters to depict the stationary characteristics. Further, the magnetic field and rotation are found to introduce oscillatory modes which were non-existent in their absence and then the principle of exchange of stability is valid. The sufficient conditions for non-existence of overstability are also obtained.

Surgical management of post-traumatic atlantoaxial rotatory fixation due to C2 facet fracture: 5 clinical cases.

PubMed

Peyriere, H; Graillon, T; Pesenti, S; Tropiano, P; Blondel, B; Fuentes, S

2017-02-01

Report the results of surgical treatment of post-traumatic atlantoaxial rotatory fixation (AARF) due to C2 articular facet fracture in adults. The records of five patients treated since 2009 for AARF due to a C2 articular facet fracture were analyzed retrospectively. Three women and two men with an average age of 60 years (27-82) were included, one of whom initially had neurological deficits. In all cases, the surgical strategy consisted of posterior fixation: Harms-type in four cases and trans-articular with hooks in one case. Dislocations due to fracture of the C2 articular facet are rare in adults; various treatment strategies have been described. In our experience, posterior screw fixation leads to satisfactory clinical and radiological outcomes. Fusion is not necessary in these cases because the dislocation is related to an asymmetric fracture without ligament damage. Posterior fixation provides satisfactory reduction of these injuries and leads to satisfactory bone union. This surgical treatment can be performed early on after the trauma and is an interesting alternative to conservative treatment. Copyright © 2016. Published by Elsevier Masson SAS.

Atlantoaxial Rotatory Subluxation: A Review for the Pediatric Emergency Physician.

PubMed

Kinon, Merritt D; Nasser, Rani; Nakhla, Jonathan; Desai, Rupen; Moreno, Jessica R; Yassari, Reza; Bagley, Carlos A

2016-10-01

Pediatric emergency physicians must have a high clinical suspicion for atlantoaxial rotatory subluxation (AARS), particularly when a child presents with neck pain and an abnormal head posture without the ability to return to a neutral position. As shown in the neurosurgical literature, timely diagnosis and swift initiation of treatment have a greater chance of treatment success for the patient. However, timely treatment is complicated because torticollis can result from a variety of maladies, including: congenital abnormalities involving the C1-C2 joint or the surrounding supporting muscles and ligaments, central nervous system abnormalities, obstetric palsies from brachial plexus injuries, clavicle fractures, head and neck surgery, and infection. The treating pediatrician must discern the etiology of the underlying problem to determine both timing and treatment paradigms, which vary widely between these illnesses. We present a comprehensive review of AARS that is intended for pediatric emergency physicians. Management of AARS can vary widely bases on factors, such as duration of symptoms, as well as the patient's history. The goal of this review is to streamline the management paradigms and provide an inclusive review for pediatric emergency first responders.

Imaging of childhood torticollis due to atlanto-axial rotatory fixation.

PubMed

Maheshwaran, S; Sgouros, S; Jeyapalan, K; Chapman, S; Chandy, J; Flint, G

1995-12-01

Atlanto-axial rotatory fixation is a rare cause of childhood torticollis. It may occur spontaneously or may be associated with trauma, upper respiratory tract infection or congenital abnormality of the cervical spine. Presentation is usually with persistent torticollis and "cock robin" deformity of the neck. In this paper the radiological experience in three patients is presented. Investigations included plain radiographs, plain anteroposterior tomography, CT and MRI. Displacement of the lateral mass of the atlas and the eccentric position of the odontoid peg can be seen in the plain films. CT scan can exclude fractures and confirm atlanto-axial rotation. The superimposition of CT images is demonstrated as a way of diagnosing subluxation. MRI offers better soft tissue differentiation and allows assessment of the integrity of the transverse ligament. This has an important bearing on the prognosis and may influence surgical treatment. It is important to recognise the plain film features of this uncommon condition and confirm the diagnosis with CT or MRI. The treatment options are discussed with particular reference to long term outcome.

The Posterior Bundle's Effect on Posteromedial Elbow Instability After a Transverse Coronoid Fracture: A Biomechanical Study.

PubMed

Shukla, Dave R; Golan, Elan; Weiser, Mitch C; Nasser, Philip; Choueka, Jack; Hausman, Michael

2018-04-01

There has been increased interest in the role of the posterior bundle of the medial collateral ligament (pMUCL) in the elbow, particularly its effects on posteromedial rotatory stability. The ligament's effect in the context of an unfixable coronoid fracture has not been the focus of any study. The purposes of this biomechanical study were to evaluate the stabilizing effect of the pMUCL with a transverse coronoid fracture and to assess the effect of graft reconstruction of the ligament. We simulated a varus and internal rotatory subluxation in 7 cadaveric elbows at 30°, 60°, and 90° elbow flexion. The amount of ulnar rotation and medial ulnohumeral joint gapping were assessed in the intact elbow after we created a transverse coronoid injury, after we divided the pMUCL, and finally, after we performed a graft reconstruction of the pMUCL. At all angles tested, some stability was lost after cutting the pMUCL once the coronoid had been injured, because mean proximal ulnohumeral joint gapping increased afterward by 2.1, 2.2, and 1.3 mm at 90°, 60°, and 30°, respectively. Ulnar internal rotation significantly increased after pMUCL transection at 90°. At 60° and 30° elbow flexion, ulnar rotation increased after resection of the coronoid but not after pMUCL resection. An uninjured pMUCL stabilizes against varus internal rotatory instability in the setting of a transverse coronoid fracture at higher flexion angles. Further research is needed to optimize graft reconstruction of the pMUCL. The pMUCL is an important secondary stabilizer against posteromedial instability in the coronoid-deficient elbow. In the setting of an unfixable coronoid fracture, the surgeon should examine for posteromedial instability and consider addressing the pMUCL surgically. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Investigation of pH and temperature on optical rotatory dispersion for noninvasive glucose monitoring

NASA Astrophysics Data System (ADS)

Baba, Justin S.; Meledeo, Adam; Cameron, B. D.; Cote, Gerard L.

2001-06-01

The widespread occurrence of diabetes mellitus and the severity of its associated complications necessitate the development of non-invasive blood glucose measurement devices in an attempt to improve treatment regimens and curb the complications associated with this disease. One method showing promise in this endeavor utilizes optical polarimetry to monitor blood glucose levels indirectly by measuring glucose rotation of polarized light, which is a direct indication of glucose concentration, in the aqueous humor of the eye. The presence of other optically active (chiral) components in the aqueous humor of the eye have the potential to confound the glucose measurement of optical rotation when using a single wavelength polarimeter. Thus, this has led to the recent investigation of multispectral polarimetric systems which have the potential to enable the removal of confounder contributions to the net observed optical rotation, therefore, increasing glucose specificity and reducing glucose prediction errors. Such polarimetric systems take advantage of the uniqueness in the rotation of polarized light, as a function of wavelength, by the chiral molecule of interest. This is commonly referred to as the optical rotatory dispersion (ORD) spectra of the chiral molecule. ORD characterization of the chiral molecules within the aqueous humor is necessary for determining the optimum number of wavelengths needed to reduce glucose prediction errors; however, this information is often only given at the sodium-D line (589 nm) in the literature. This report describes the system we designed and built to measure ORD spectra for glucose and for albumin, the main optical confounder within the aqueous humor, as well as our investigation of the effects of temperature and pH on these ORD spectra.

A study of acceptability & feasibility of integrating humanities based study modules in undergraduate curriculum

PubMed Central

Gurtoo, Anil; Ranjan, Piyush; Sud, Ritika; Kumari, Archana

2013-01-01

Background & objectives: The field of medical education in our country remains deeply fragmented and polarised between the biomedical technical domains which are overrepresented and the humanitarian domains which are under-represented within the universe of medical pedagogy. To overcome this imbalance, we designed a module that integrates the two domains in a holistic biomedical and socio-cultural framework with the objective of providing unified field of learning experience to the undergraduate medical students attending rotatory clinical postings in a medical college in New Delhi, India. Methods: Undergraduate medical students of 6th and 8th semesters were enrolled in humanities based study module (HSM) on voluntary basis for a total duration of six months. During their compulsory rotatory medicine ward posting, they were introduced and exposed to learning bedside experience of HSM with various tools of art and literature in the form of poem, short narratives, paintings, sketches and group discussions to express their feelings about patients’ sufferings. Students’ feed-back was recorded through an anonymized questionnaire. Result: Of the 235 students, 223 (95%) enrolled themselves voluntarily and 94 per cent (210 of 223) of them completed the total six month duration of the study module. Seventy three per cent of the students found HSM effective in improving their affective motivational behavior, 82 per cent found it effective in motivating them to learn more about core medical subjects, and 85 per cent wanted its continuation as part of medical curriculum. Interpretation & conclusions: The positive response of the students towards the HSM was an indicator of the potential for integrating the module within the undergraduate medical curriculum. PMID:23481073

An In Vitro Robotic Assessment of the Anterolateral Ligament, Part 2: Anterolateral Ligament Reconstruction Combined With Anterior Cruciate Ligament Reconstruction.

PubMed

Nitri, Marco; Rasmussen, Matthew T; Williams, Brady T; Moulton, Samuel G; Cruz, Raphael Serra; Dornan, Grant J; Goldsmith, Mary T; LaPrade, Robert F

2016-03-01

Recent biomechanical studies have demonstrated that an extra-articular lateral knee structure, most recently referred to as the anterolateral ligament (ALL), contributes to overall rotational stability of the knee. However, the effect of anatomic ALL reconstruction (ALLR) in the setting of anterior cruciate ligament (ACL) reconstruction (ACLR) has not been biomechanically investigated or validated. The purpose of this study was to investigate the biomechanical function of anatomic ALLR in the setting of a combined ACL and ALL injury. More specifically, this investigation focused on the effect of ALLR on resultant rotatory stability when performed in combination with concomitant ACLR. It was hypothesized that ALLR would significantly reduce internal rotation and axial plane translation laxity during a simulated pivot-shift test compared with isolated ACLR. Controlled laboratory study. Ten fresh-frozen cadaveric knees were evaluated with a 6 degrees of freedom robotic system. Knee kinematics were evaluated with simulated clinical examinations including a simulated pivot-shift test consisting of coupled 10-N·m valgus and 5-N·m internal rotation torques, a 5-N·m internal rotation torque, and an 88-N anterior tibial load. Kinematic differences between ACLR with an intact ALL, ACLR with ALLR, and ACLR with a deficient ALL were compared with the intact state. Single-bundle ACLR tunnels and ALLR tunnels were placed anatomically according to previous quantitative anatomic attachment descriptions. Combined anatomic ALLR and ACLR significantly improved the rotatory stability of the knee compared with isolated ACLR in the face of a concurrent ALL deficiency. During a simulated pivot-shift test, ALLR significantly reduced internal rotation and axial plane tibial translation when compared with ACLR with an ALL deficiency. Isolated ACLR for the treatment of a combined ACL and ALL injury was not able to restore stability of the knee, resulting in a significant increase in residual internal rotation laxity. ALLR did not affect anterior tibial translation; no significant differences were observed between the varying ALL conditions with ACLR except between ACLR with an intact ALL and ACLR with a deficient ALL at 0° of flexion. In the face of a combined ACL and ALL deficiency, concurrent ACLR and ALLR significantly improved the rotatory stability of the knee compared with solely reconstructing the ACL. Significant increases in residual internal rotation and laxity during the pivot-shift test may exist in both acute and chronic settings of an ACL deficiency and in patients treated with isolated ACLR for a combined ACL and ALL deficiency. For this subset of patients, surgical treatment of the ALL, in addition to ACLR, should be considered to restore knee stability. © 2016 The Author(s).

Frenkel-exciton decomposition analysis of circular dichroism and circularly polarized luminescence for multichromophoric systems.

PubMed

Shiraogawa, Takafumi; Ehara, Masahiro; Jurinovich, Sandro; Cupellini, Lorenzo; Mennucci, Benedetta

2018-06-15

Recently, a method to calculate the absorption and circular dichroism (CD) spectra based on the exciton coupling has been developed. In this work, the method was utilized for the decomposition of the CD and circularly polarized luminescence (CPL) spectra of a multichromophoric system into chromophore contributions for recently developed through-space conjugated oligomers. The method which has been implemented using rotatory strength in the velocity form and therefore it is gauge-invariant, enables us to evaluate the contribution from each chromophoric unit and locally excited state to the CD and CPL spectra of the total system. The excitonic calculations suitably reproduce the full calculations of the system, as well as the experimental results. We demonstrate that the interactions between electric transition dipole moments of adjacent chromophoric units are crucial in the CD and CPL spectra of the multichromophoric systems, while the interactions between electric and magnetic transition dipole moments are not negligible. © 2018 Wiley Periodicals, Inc. © 2018 Wiley Periodicals, Inc.

Chiroplasmonic magnetic gold nanocomposites produced by one-step aqueous method using κ-carrageenan.

PubMed

Lesnichaya, Marina V; Sukhov, Boris G; Aleksandrova, Galina P; Gasilova, Ekaterina R; Vakul'skaya, Tamara I; Khutsishvili, Spartak S; Sapozhnikov, Anatoliy N; Klimenkov, Igor V; Trofimov, Boris A

2017-11-01

Novel water-soluble chiroplasmonic nanobiocomposites with directly varied gold content were synthesized by a one-step redox method in water using a biocompatible polysaccharide κ-carrageenan (industrial product from algae) as both reducing and stabilizing matrix. The influence of the reactants ratio, temperature, and pH on the reaction was studied and the optimal reaction parameters were found. The structure and the properties of composite nanomaterials were examined in solid state and aqueous solutions by using complementary physical-chemical methods X-ray diffraction analysis, transmission electron microscopy, spectroscopy of electron paramagnetic resonance, atomic absorption and optical spectroscopy, polarimetry including optical rotatory dispersion with registration of interphase-crossbred Cotton effect of a chiral polysaccharide matrix on plasmonic chromophore of gold nanoparticles, dynamic and static light scattering. The new perspective multi-purpose nanocomposites demonstrate a complex of chiroplasmonic and magnetic properties, imparted by both nanoparticles and radicals enriched chiral polysaccharide matrix. Copyright © 2017 Elsevier Ltd. All rights reserved.

Nonlinear vibrations and dynamic stability of viscoelastic orthotropic rectangular plates

NASA Astrophysics Data System (ADS)

Eshmatov, B. Kh.

2007-03-01

This paper describes the analyses of the nonlinear vibrations and dynamic stability of viscoelastic orthotropic plates. The models are based on the Kirchhoff-Love (K.L.) hypothesis and Reissner-Mindlin (R.M.) generalized theory (with the incorporation of shear deformation and rotatory inertia) in geometrically nonlinear statements. It provides justification for the choice of the weakly singular Koltunov-Rzhanitsyn type kernel, with three rheological parameters. In addition, the implication of each relaxation kernel parameter has been studied. To solve problems of viscoelastic systems with weakly singular kernels of relaxation, a numerical method has been used, based on quadrature formulae. With a combination of the Bubnov-Galerkin and the presented method, problems of nonlinear vibrations and dynamic stability in viscoelastic orthotropic rectangular plates have been solved, according to the K.L. and R.M. hypotheses. A comparison of the results obtained via these theories is also presented. In all problems, the convergence of the Bubnov-Galerkin method has been investigated. The implications of material viscoelasticity on vibration and dynamic stability are presented graphically.

An atomic orbital based real-time time-dependent density functional theory for computing electronic circular dichroism band spectra

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

Goings, Joshua J.; Li, Xiaosong, E-mail: xsli@uw.edu

2016-06-21

One of the challenges of interpreting electronic circular dichroism (ECD) band spectra is that different states may have different rotatory strength signs, determined by their absolute configuration. If the states are closely spaced and opposite in sign, observed transitions may be washed out by nearby states, unlike absorption spectra where transitions are always positive additive. To accurately compute ECD bands, it is necessary to compute a large number of excited states, which may be prohibitively costly if one uses the linear-response time-dependent density functional theory (TDDFT) framework. Here we implement a real-time, atomic-orbital based TDDFT method for computing the entiremore » ECD spectrum simultaneously. The method is advantageous for large systems with a high density of states. In contrast to previous implementations based on real-space grids, the method is variational, independent of nuclear orientation, and does not rely on pseudopotential approximations, making it suitable for computation of chiroptical properties well into the X-ray regime.« less

Solvent Effects on Emission Yield and Lifetime for Coumarin Laser Dyes. Requirements for a Rotatory Decay Mechanism.

DTIC Science & Technology

1983-10-31

spectral shifts and sizeable solvent iso- tope effects have been frequently observed for solvent exciplexes , e in contrast to our findings. The results also...49. Chandross, E. A.; "The Exciplex " Gordon, M.; Ware, W. R. (ed.) 4 Academic Press, Inc.: New York; 1975; p 187. SO. a. Beecroft, R. A.; Davidson, R

Pestalotiopens A and B: stereochemically challenging flexible sesquiterpene-cyclopaldic acid hybrids from Pestalotiopsis sp.

PubMed

Hemberger, Yasmin; Xu, Jing; Wray, Victor; Proksch, Peter; Wu, Jun; Bringmann, Gerhard

2013-11-11

From the endophytic fungus Pestalotiopsis sp. isolated from the leaves of the Chinese mangrove, Rhizophora mucronata, two novel hybrid sesquiterpene-cyclopaldic acid metabolites with an unusual carbon skeleton, named pestalotiopens A and B, were obtained, together with the already known phytotoxin altiloxin B. Pestalotiopen B even contains a third, triketide-derived module. The constitutions and the absolute configurations of the new metabolites and of altiloxin B were unambiguously determined by a combination of spectroscopic methods and quantum-chemical optical-rotatory dispersion (ORD) and circular dichroism (CD) calculations. A biosynthetic pathway to pestalotiopens A and B is proposed with altiloxin B as one of the suggested precursors. Pestalotiopen A shows moderate antimicrobial activity against Enterococcus faecalis. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Double-bundle ACL reconstruction can improve rotational stability.

PubMed

Yagi, Masayoshi; Kuroda, Ryosuke; Nagamune, Kouki; Yoshiya, Shinichi; Kurosaka, Masahiro

2007-01-01

Double-bundle anterior cruciate ligament (ACL) reconstruction reproduces anteromedial and posterolateral bundles, and thus has theoretical advantages over conventional single-bundle reconstruction in controlling rotational torque in vitro. However, its superiority in clinical practice has not been proven. We analyzed rotational stability with three reconstruction techniques in 60 consecutive patients who were randomly divided into three groups (double-bundle, anteromedial single-bundle, posterolateral single-bundle). In the reconstructive procedure, the hamstring tendon was harvested and used as a free tendon graft. Followup examinations were performed 1 year after surgery. Anteroposterior laxity of the knee was examined with a KT-1000 arthrometer, whereas rotatory instability, as elicited by the pivot shift test, was assessed using a new measurement system incorporating three-dimensional electromagnetic sensors. Routine clinical evaluations, including KT examination, demonstrated no differences among the three groups. However, using the new measurement system, patients with double-bundle ACL reconstruction showed better pivot shift control of complex instability than patients with anteromedial and posterolateral single-bundle reconstruction.

Anatomy and Histology of the Knee Anterolateral Ligament.

PubMed

Helito, Camilo Partezani; Demange, Marco Kawamura; Bonadio, Marcelo Batista; Tírico, Luis Eduardo Passarelli; Gobbi, Riccardo Gomes; Pécora, José Ricardo; Camanho, Gilberto Luis

2013-12-01

Reconstruction of the anterior cruciate ligament (ACL) is one of the most common procedures in orthopaedic surgery. However, even with advances in surgical techniques and implants, some patients still have residual anterolateral rotatory laxity after reconstruction. A thorough study of the anatomy of the anterolateral region of the knee is needed. To study the anterolateral region and determine the measurements and points of attachments of the anterolateral ligament (ALL). Descriptive laboratory study. Dissections of the anterolateral structures of the knee were performed in 20 human cadavers. After isolating the ALL, its length, thickness, width, and points of attachments were determined. The femoral attachment of the ALL was based on the anterior-posterior and proximal-distal distances from the attachment of the lateral collateral ligament (LCL). The tibial attachment point was based on the distance from the Gerdy tubercle to the fibular head and the distance from the lateral tibial plateau. The ligaments from the first 10 dissections were sent for histological analysis. The ALL was found in all 20 knees. The femoral attachment of the ALL at the lateral epicondyle averaged 3.5 mm distal and 2.2 mm anterior to the attachment of the LCL. Two distal attachments were observed: one inserts into the lateral meniscus, the other between the Gerdy tubercle and the fibular head, approximately 4.4 mm distal to the tibial articular cartilage. The mean measurements for the ligament were 37.3 mm (length), 7.4 mm (width), and 2.7 mm (thickness). The histological analysis of the ligaments revealed dense connective tissue. The ALL is consistently present in the anterolateral region of the knee. Its attachment to the femur is anterior and distal to the attachment of the LCL. Moving distally, it bifurcates at close to half of its length. The ALL features 2 distal attachments, one at the lateral meniscus and the other between the Gerdy tubercle and the fibular head. The ALL may be important in maintaining normal rotatory limits of knee motion; ALL rupture could be responsible for rotatory laxity after isolated intra-articular reconstruction of the ACL.

Vertebral rotatory subluxation in degenerative scoliosis: facet joint tropism is related.

PubMed

Bao, Hongda; Zhu, Feng; Liu, Zhen; Bentley, Mark; Mao, Saihu; Zhu, Zezhang; Ding, Yitao; Qiu, Yong

2014-12-15

A cross-sectional study. To identify facet tropism as one of the possible risk factors leading to vertebral rotatory subluxation (VRS). VRS has been considered as one of the prognostic factors for degenerative scoliosis. Although several risk factors of VRS, including age and Cobb angle, have been investigated, few studies exist that have evaluated the correlation between VRS and anatomical structures of the vertebral column. This retrospective study recruited 23 patients diagnosed with degenerative lumbar scoliosis with VRS and 20 patients with degenerative scoliosis without VRS. The lateral translation on coronal radiographs was measured and 5 mm was used as the cutoff value to define rotatory subluxation. Computed tomographic scans for facet joints were made for all lumbar levels. The difference between right and left facet angles was recorded as ΔFA. Facet tropism was defined as a difference between the bilateral facet angles of more than 10°. In this study, VRS was most commonly found at the L3-L4 level (49%) and, with decreasing frequency at L2-L3 (24%), L4-L5 (20%), and L1-L2 (7%). On the convex side of the main curve, face joints at levels with VRS were more coronally oriented compared with those at levels without VRS (41.64° ± 11.65° vs. 36.30° ± 10.99°, P = 0.034). ΔFA was also significantly different between levels with and without VRS (P = 0.005). A strong correlation was found between ΔFA and lateral translation, with a coefficient of 0.33 (P < 0.001). In addition, ΔFA and a larger Cobb angle were found to be significantly associated with VRS based on binary regression analysis, with an odds ratio of 4.68 and 2.14, respectively. Facet tropism was more significantly observed at levels with VRS. On the convex side of the main curve, facet joints at levels with VRS were more coronally oriented. A larger Cobb angle and severe facet tropism in degenerative scoliosis should be considered to be related to VRS.

ACL double-bundle reconstruction with one tibial tunnel provides equal stability compared to two tibial tunnels.

PubMed

Drews, Björn Holger; Seitz, Andreas Martin; Huth, Jochen; Bauer, Gerhard; Ignatius, Anita; Dürselen, Lutz

2017-05-01

The purpose of this study was to investigate whether an anterior cruciate ligament (ACL) double-bundle reconstruction with one tibial tunnel displays the same in vitro stability as a conventional double-bundle reconstruction with two tibial tunnels when using the same tensioning protocol. In 11 fresh-frozen cadaveric knees, ACL double-bundle reconstruction with one and two tibial tunnels was performed. The two grafts were tightened using 80 N in different flexion angles (anteromedial-bundle at 60° and posterolateral-bundle at 15°). Anterior tibial translation (134 N) and translation with combined rotatory and valgus loads (10 Nm valgus stress and 4 Nm internal tibial torque) were determined at 0°, 30°, 60° and 90° flexion. Measurements were taken in intact ACL, resected ACL, three-tunnel reconstruction and four-tunnel reconstruction. Additionally, the tension on the grafts was determined. Student's t test was performed for statistical analysis of the related samples. Significance was set at p < 0.017 according to Bonferroni correction. The two reconstructive techniques displayed no significant differences in comparison with the intact ACL in anterior tibial translation at 0°, 60° and 90° of flexion. The same results were obtained for the anterior tibial translation with a combined rotatory load at 60° and 90°. When directly comparing both reconstructive techniques, there were no significant differences for the anterior tibial translation and combined rotatory load at all flexion angles. The measured tension on grafts displayed similar load sharing between both bundles. Except at full extension, both grafts displayed a significantly different tension increase under anterior tibial translation for both techniques (p = 0.0086). Tightening both bundles in ACL double-bundle reconstruction with one or two tibial tunnels in different flexion angles achieved comparable restoration of stability, although there was different load sharing on the bundles. With regard to individualized ACL reconstruction, the double-bundle technique with one tibial tunnel offers a possibility to address small tibial insertion sites without compromising the advantages of a double-bundle procedure.

Correlation between vestibulo-ocular reflex and optokinetic afternystagmus in normal subjects and in patients with vestibular system disorders

PubMed Central

Dellepiane, M; Medicina, MC; Barettini, L; Mura, AC

2006-01-01

Summary Optokinetic afternystagmus follows optokinetic nystagmus as an expression of the central velocity storage integrator discharge and its fast phase is beating in the same direction as the previous optokinetic nystagmus. We investigated the correlation between vestibulo-ocular reflex and optokinetic afternystagmus in normal subjects and in patients with bilateral vestibular disorders. The aim of this study was to determine the possible role of optokinetic afternystagmus as a diagnostic test for identifying functional vestibular disorders. The subjects were examined by electronystagmography and vestibulo-ocular reflex, optokinetic nystagmus stare type as well as optokinetic afternystagmus were recorded. They were restrained in a rotatory drum chair, both the chair and the drum could be rotated, independently or coupled. For vestibulo-ocular reflex analysis, we studied post-rotatory-nystagmus from a velocity of 90°s. Optokinetic nystagmus was recorded at a drum velocity of 30°s and the registration continued in total darkness, after the illumination was switched off, to study optokinetic afternystagmus. We considered vestibulo-ocular reflex and optokinetic nystagmus gain, vestibulo-ocular reflex and optokinetic afternystagmus constant of time (tc) defined as the time necessary for the slow phase eye velocity to be reduced to 37% of its initial value. Results demonstrated that vestibulo-ocular reflex gain and ct showed a significant difference only in patients with reduced vestibular reflexia, while optokinetic nystagmus gain was greater only in patients with increased reflexia; optokinetic afternystagmus ct was different from the control group only in patients with hyporeflexia. In conclusion, our results suggest that vestibulo-ocular reflex and optokinetic afternystagmus ct are clinically more useful than the gain alone in testing vestibular disorders with hyporeflexia. On the other hand, we propose a new mathematical and statistical approach to study the temporal evolution of more parameters of the nystagmus. PMID:18383753

Radioracemization and radiation-induced chiral amplification of chiral terpenes measured by optical rotatory dispersion (ORD) spectroscopy

NASA Astrophysics Data System (ADS)

Cataldo, Franco; Ursini, Ornella; Angelini, Giancarlo

2008-08-01

For the first time the radioracemization of α(+)pinene and α(-)pinene, of turpentine and of R(-)- α-phellandrene has been studied by optical rotatory dispersion (ORD) spectroscopy. For all these compounds, the radioracemization implies a shift of the ORD curves toward lower levels of specific optical rotation. The radioracemization degree ( RR) has been defined and calculated for all the compounds studied. It has been found that for radiation dose of 1 MGy the radioracemization degree is about 4.5% for the compound with the highest optical purity and reaches 7-8% for the less optically pure compounds, demonstrating that impurities can affect greatly the radioracemization. In contrast with the general radioracemization effect exerted by high-energy radiation on chiral molecules, β(-)pinene, β(+)pinene when irradiated show an increment of their specific optical rotation. This fact has been measured for the first time by ORD spectroscopy and the amplification degree of chirality can reach 1000% in the near UV. This phenomenon is due to the formation of a chiral polymer, poly- β-pinene, which forms a solution with the monomer enhancing its optical activity. The implications for the theories of the origin of life of such unexpected phenomenon are discussed briefly.

Influence of dynamic contact of hard contact lens materials on corneal epithelial cells examined by rose bengal staining.

PubMed

Iguchi, I; Kamiyama, K; Imamichi, M; Ohashi, T; He, J; Wang, X; Imanishi, J

1996-06-01

To establish a method for evaluation of less irritating contact lens materials by dynamic contact with cornea, we examined epithelial and endothelial cell injury to the porcine cornea caused by rotatory rubbing with four kinds of hard contact lenses (HCL). The HCLs used were (1) polymethylmethacrylate (PMMA) HCL, (2) gas-permeable HCL composed of a graft co-polymer of dextran derivative and methylmethacrylate (MMA) (Suncon Mild II(TM), 12 Dk), (3) gas-permeable HCL composed of a graft co-polymer of dextran derivative, a monomer containing silicone, a monomer containing fluorine and MMA (New Dx HCL-136, 32 Dk), and (4) gas-permeable HCL composed of a monomer containing silicone, a monomer containing fluorine and MMA(RGPL-A, 216 Dk). Using a specially designed apparatus, we produced a standardized injury to the epithelium or endothelium of porcine corneas by holding the HCL against the corneal surface while rotating the lens rapidly. After rotatory rubbing of the HCL on the epithelium, the degree of rose bengal staining of the epithelial cells, indicating degeneration of the cells and mucin detachment, were significantly different among these HCLs (New Dx HCL-136 < Suncon Mild II(TM), PPMA < RGPL-A), and the cell injury rates of the endothelium were also significantly different among them (Suncon Mild II(TM) < New Dx HCL-136, PMMA < RGPL-A). The water-wettability of HCLs was not directly correlated with cell injury rates on epithelial and endothelial cells. Both the New Dx HCL-136 and Suncon Mild II(TM), which have a common composition of graft co-polymer of dextran derivative, are less irritating to the epithelium and to the endothelium. Also a very few patients complaints regarding Suncon Mild II(TM) wearing in individuals with dry eyes have been reported. Therefore, we would expect that the New Dx HCL-136 should be satisfactory for wear by individuals with dry eyes.

Local mechanical response of cells to the controlled rotation of magnetic nanorods.

PubMed

Castillo, Matias; Ebensperger, Roberto; Wirtz, Denis; Walczak, Magdalena; Hurtado, Daniel E; Celedon, Alfredo

2014-11-01

The mechanical response of the cytoplasm was investigated by the intracellular implantation of magnetic nanorods and exposure to low-frequency rotatory magnetic fields. Nanorods (Pt-Ni, ∼200 nm diameter) fabricated by electrodeposition in templates of porous alumina with lengths of approximately 2 and 5 µm were inserted into NIH/3T3 fibroblasts and manipulated with a rotational magnetic field. Nanorod rotation was observed only for torques greater than 3.0 × 10(-16) Nm, suggesting a Bingham-type behavior of the cytoplasm. Higher torques produced considerable deformation of the intracellular material. The cell nucleus and cell membrane were significantly deformed by nanorods actuated by 4.5 × 10(-15) Nm torques. Our results demonstrate that nanorods under magnetic fields are an effective tool to mechanically probe the intracellular environment. We envision that our findings may contribute to the noninvasive and direct mechanical characterization of the cytoplasm. © 2014 Wiley Periodicals, Inc.

Local mechanical response of cells to the controlled rotation of magnetic nanorods

PubMed Central

Castillo, Matias; Ebensperger, Roberto; Wirtz, Denis; Walczak, Magdalena; Hurtado, Daniel E.; Celedon, Alfredo

2015-01-01

The mechanical response of the cytoplasm was investigated by the intracellular implantation of magnetic nanorods and exposure to low-frequency rotatory magnetic fields. Nanorods (Pt-Ni, ~200 nm diameter) fabricated by electrodeposition in templates of porous alumina with lengths of approximately 2 and 5 μm were inserted into NIH/ 3T3 fibroblasts and manipulated with a rotational magnetic field. Nanorod rotation was observed only for torques greater than 3.0 × 10−16 Nm, suggesting a Bingham-type behavior of the cytoplasm. Higher torques produced considerable deformation of the intracellular material. The cell nucleus and cell membrane were significantly deformed by nanorods actuated by 4.5 × 10−15 Nm torques. Our results demonstrate that nanorods under magnetic fields are an effective tool to mechanically probe the intracellular environment. We envision that our findings may contribute to the noninvasive and direct mechanical characterization of the cytoplasm. PMID:24700696

Radiographic assessment of knee joint rotation.

PubMed Central

Straiton, J A; Todd, B; Venner, R M

1987-01-01

A radiographic technique for measuring conjunct rotation at the knee joint is described. Conjunct rotation was demonstrated to occur over a greater range of values of flexion than conventionally believed. Rotation increased progressively as the knee extended, and was not confined to the last phase of extension. Consideration of such rotatory movement is relevant to the design of knee arthroplasties and also to possible mechanisms of non-bony injury of the knee. PMID:3503049

The E-music box: an empirical method for exploring the universal capacity for musical production and for social interaction through music

PubMed Central

Novembre, Giacomo; Varlet, Manuel; Muawiyath, Shujau; Stevens, Catherine J.; Keller, Peter E.

2015-01-01

Humans are assumed to have a natural—universal—predisposition for making music and for musical interaction. Research in this domain is, however, typically conducted with musically trained individuals, and therefore confounded with expertise. Here, we present a rediscovered and updated invention—the E-music box—that we establish as an empirical method to investigate musical production and interaction in everyone. The E-music box transforms rotatory cyclical movements into pre-programmable digital musical output, with tempo varying according to rotation speed. The user’s movements are coded as continuous oscillatory data, which can be analysed using linear or nonlinear analytical tools. We conducted a proof-of-principle experiment to demonstrate that, using this method, pairs of non-musically trained individuals can interact according to conventional musical practices (leader/follower roles and lower-pitch dominance). The results suggest that the E-music box brings ‘active’ and ‘interactive’ musical capacities within everyone’s reach. We discuss the potential of this method for exploring the universal predisposition for music making and interaction in developmental and cross-cultural contexts, and for neurologic musical therapy and rehabilitation. PMID:26715993

The E-music box: an empirical method for exploring the universal capacity for musical production and for social interaction through music.

PubMed

Novembre, Giacomo; Varlet, Manuel; Muawiyath, Shujau; Stevens, Catherine J; Keller, Peter E

2015-11-01

Humans are assumed to have a natural-universal-predisposition for making music and for musical interaction. Research in this domain is, however, typically conducted with musically trained individuals, and therefore confounded with expertise. Here, we present a rediscovered and updated invention-the E-music box-that we establish as an empirical method to investigate musical production and interaction in everyone. The E-music box transforms rotatory cyclical movements into pre-programmable digital musical output, with tempo varying according to rotation speed. The user's movements are coded as continuous oscillatory data, which can be analysed using linear or nonlinear analytical tools. We conducted a proof-of-principle experiment to demonstrate that, using this method, pairs of non-musically trained individuals can interact according to conventional musical practices (leader/follower roles and lower-pitch dominance). The results suggest that the E-music box brings 'active' and 'interactive' musical capacities within everyone's reach. We discuss the potential of this method for exploring the universal predisposition for music making and interaction in developmental and cross-cultural contexts, and for neurologic musical therapy and rehabilitation.

Investigation of Solvation Effects on Optical Rotatory Dispersion Using the Polarizable Continuum Model

NASA Astrophysics Data System (ADS)

Aharon, Tal; Lemler, Paul M.; Vaccaro, Patrick; Caricato, Marco

2017-06-01

The Optical Rotatory Dispersion (ORD) of a chiral solute is heavily affected by solvation, but this effect does not follow the usual correlation with the solvent polarity, i.e., larger solvent polarity does not imply a larger change in the solute's property. Therefore, a great deal of experimental and theoretical effort has been directed towards correlating the solvation effect on the ORD and the solvent properties. This discovery followed from the development of cavity ring down polarimetry (CRPD), which allows measurements of gas-phase ORD. In order to investigate this phenomenon, we chose a set of five rigid molecules to limit the effect of molecular vibrations and isolate the role of solvation. The latter was investigated with the Polarizable Continuum Model (PCM), and compared to experimental results. We used Bondi radii to build the PCM cavity, and performed extensive calculations at multiple frequencies using density functional theory (DFT) with two functionals: B3LYP and CAM-B3LYP, together with the aug-cc-pVDZ basis set. We also performed coupled cluster singles and doubles (CCSD/aug-cc-pVDZ) calculations at the wavelengths where gas-phase data are available, all of which are augmented with zero point vibrational corrections. These results are compared to experimental data and seem to indicate that PCM does not entirely account for the environmental effects on the ORD.

PARAMETERS OF TEXTURE CHANGE IN PROCESSED FISH: MYOSIN DENATURATION.

PubMed

Chu, George Hao; Sterling, Clarence

1970-03-01

The white muscle of the Sacramento blackfish (Orthodon microlepidotus) was processed by freezing, dehydration, and cooking. Myosin was extracted immediately afterwards or following a period of storage in order to examine evidence for denaturation. The tests used were the solubility of whole muscle protein and the intrinsic viscosity, isoelectric point, ATPase activity, ultra-violet absorption spectrum, and optical rotatory dispersion of purified myosin extract. Almost all measures used showed that denaturation increased in the order: fresh < frozen < frozen-stored < dehydrated < dehydrated-stored < cooked.

Response of long, flexible cantilever beams applied root motions. [spacecraft structures

NASA Technical Reports Server (NTRS)

Fralich, R. W.

1976-01-01

Results are presented for an analysis of the response of long, flexible cantilever beams to applied root rotational accelerations. Maximum values of deformation, slope, bending moment, and shear are found as a function of magnitude and duration of acceleration input. Effects of tip mass and its eccentricity and rotatory inertia on the response are also investigated. It is shown that flexible beams can withstand large root accelerations provided the period of applied acceleration can be kept small relative to the beam fundamental period.

Posterolateral rotatory instability from multiple steroids injections for tennis elbow: a case report.

PubMed

Chanlalit, Cholawish; Limsricharoen, Warodom

2013-01-01

This article reports the complication (lateral collateral ligament rupture) arising from improper numbers of steroids injections for the chronic lateral elbow pain (tennis elbow). Clinical sign and investigation with MRI confirmed a diagnosis of LCL rupture. In the present report, we describe the successful outcome of one year results in surgical debridement and lateral collateral ligament (LCL) reconstruction. A discussion of the proper conservative role for the chronic lateral epicondyalgia and the surgical decision to resolve this complication is also included.

Functional anatomy of the lateral collateral ligament of the elbow.

PubMed

Hackl, M; Bercher, M; Wegmann, K; Müller, L P; Dargel, J

2016-07-01

The aim of this study was to analyze the functional anatomy of the lateral collateral ligament complex (LCLC) and the surrounding forearm extensors. Using 81 human cadaveric upper extremities, the anatomy of the forearm extensors-especially the anconeus, supinator and extensor carpi ulnaris (ECU)-was analyzed. After removal of aforementioned extensors the functional anatomy of the LCLC was analyzed. The origin of the LCLC was evaluated for isometry. The insertion types of the lateral ulnar collateral ligament (LUCL) were analyzed and classified. The ECU runs parallel to the RCL to dynamically preserve varus stability. The supinator and anconeus muscle fibers coalesce with the LCLC and lengthen during pronation. The anconeus fibers run parallel to the LUCL in full flexion. The LCLC consists of the annular ligament (AL) and the isometric radial collateral ligament (RCL). During elbow flexion, its posterior branches (LUCL) tighten while the anterior branches loosen. When performing a pivot shift test, the loosened LUCL fibers do not fully tighten in full extension. The LUCL inserts along with the AL at the supinator crest. Three different insertion types could be observed. The LUCL represents the posterior branch of the RCL rather than a distinct ligament. It is non-isometric and lengthens during elbow flexion. The RCL was found to be of vital importance for neutralization of posterolateral rotatory forces. Pronation of the forearm actively stabilizes the elbow joint as the supinator, anconeus and biceps muscle work in unison to increase posterolateral rotatory stability.

Posterior horn instability of the medial meniscus a sign of posterior meniscotibial ligament insufficiency.

PubMed

Mariani, P P

2011-07-01

In longstanding chronic anterior cruciate ligament (ACL) insufficiency, we identified an abnormal movement of the posterior medial meniscal horn, likely due to insufficiency of the posteromedial meniscotibial ligament. Passing from extension to flexion or vice versa, the medial posterior horn slides below the posterior rim of the tibia exposing the tibial plateau. Fixation with suture anchors of the meniscotibial ligament through a posteromedial portal restored normal meniscotibial tension and reduced instability of the meniscal posterior horn. The purpose of the present study was to present the arthroscopic features of posterior medial meniscus instability and to report results following arthroscopic repair. During the two-year study period, from 2007 through 2008, this arthroscopic feature was detected in 12 patients, 5 patients had failure of a previous ACL reconstruction and 7 patients had delay in ligamentous reconstruction for various reasons. All patients were affected by severe anterior-posterior translation with 11.3 ± 4.3 mm of side-to-side difference at KT-2000 and by associated rotatory laxity with grade 3 of pivot shift. At follow-up of 1 year, the combined ACL reconstruction and fixation of the posteromedial horn showed a reduction in the rotatory and anteroposterior laxity. This study suggests the importance of a proper arthroscopic evaluation of the posterior medial capsule in patients with chronic ACL insufficiency and highlights the potential presence of an unstable posterior horn of the medial meniscus as an indirect arthroscopic sign of peripheral laxity.

Free vibration of arches flexible in shear.

NASA Technical Reports Server (NTRS)

Austin, W. J.; Veletsos, A. S.

1973-01-01

An analysis reported by Veletsos et al. (1972) concerning the free vibrational characteristics of circular arches vibrating in their own planes is considered. The analysis was based on a theory which neglects the effects of rotatory inertia and shearing deformation. A supplementary investigation is conducted to assess the effects of the previously neglected factors and to identify the conditions under which these effects are of practical significance or may be neglected. A simple approximate procedure is developed for estimating the natural frequencies of arches, giving due consideration to the effects of the previously neglected factors.

Explicit frequency equations of free vibration of a nonlocal Timoshenko beam with surface effects

NASA Astrophysics Data System (ADS)

Zhao, Hai-Sheng; Zhang, Yao; Lie, Seng-Tjhen

2018-02-01

Considerations of nonlocal elasticity and surface effects in micro- and nanoscale beams are both important for the accurate prediction of natural frequency. In this study, the governing equation of a nonlocal Timoshenko beam with surface effects is established by taking into account three types of boundary conditions: hinged-hinged, clamped-clamped and clamped-hinged ends. For a hinged-hinged beam, an exact and explicit natural frequency equation is obtained. However, for clamped-clamped and clamped-hinged beams, the solutions of corresponding frequency equations must be determined numerically due to their transcendental nature. Hence, the Fredholm integral equation approach coupled with a curve fitting method is employed to derive the approximate fundamental frequency equations, which can predict the frequency values with high accuracy. In short, explicit frequency equations of the Timoshenko beam for three types of boundary conditions are proposed to exhibit directly the dependence of the natural frequency on the nonlocal elasticity, surface elasticity, residual surface stress, shear deformation and rotatory inertia, avoiding the complicated numerical computation.

In Vitro Mass Propagation of Cymbopogon citratus Stapf., a Medicinal Gramineae.

PubMed

Quiala, Elisa; Barbón, Raúl; Capote, Alina; Pérez, Naivy; Jiménez, Elio

2016-01-01

Cymbopogon citratus (D.C.) Stapf. is a medicinal plant source of lemon grass oils with multiple uses in the pharmaceutical and food industry. Conventional propagation in semisolid culture medium has become a fast tool for mass propagation of lemon grass, but the production cost must be lower. A solution could be the application of in vitro propagation methods based on liquid culture advantages and automation. This chapter provides two efficient protocols for in vitro propagation via organogenesis and somatic embryogenesis of this medicinal plant. Firstly, we report the production of shoots using a temporary immersion system (TIS). Secondly, a protocol for somatic embryogenesis using semisolid culture for callus formation and multiplication, and liquid culture in a rotatory shaker and conventional bioreactors for the maintenance of embryogenic culture, is described. Well-developed plants can be achieved from both protocols. Here we provide a fast and efficient technology for mass propagation of this medicinal plant taking the advantage of liquid culture and automation.

Stereochemical analysis of (+)-limonene using theoretical and experimental NMR and chiroptical data

NASA Astrophysics Data System (ADS)

Reinscheid, F.; Reinscheid, U. M.

2016-02-01

Using limonene as test molecule, the success and the limitations of three chiroptical methods (optical rotatory dispersion (ORD), electronic and vibrational circular dichroism, ECD and VCD) could be demonstrated. At quite low levels of theory (mpw1pw91/cc-pvdz, IEFPCM (integral equation formalism polarizable continuum model)) the experimental ORD values differ by less than 10 units from the calculated values. The modelling in the condensed phase still represents a challenge so that experimental NMR data were used to test for aggregation and solvent-solute interactions. After establishing a reasonable structural model, only the ECD spectra prediction showed a decisive dependence on the basis set: only augmented (in the case of Dunning's basis sets) or diffuse (in the case of Pople's basis sets) basis sets predicted the position and shape of the ECD bands correctly. Based on these result we propose a procedure to assign the absolute configuration (AC) of an unknown compound using the comparison between experimental and calculated chiroptical data.

HPLC profiling of antimicrobial and antioxidant phyco sugars isolated from the South West coast of India.

PubMed

Kailas, Abhilash Parameswaran; Nair, Sukumaran Muraleedharan

2016-10-20

Phyco sugars isolated from the South West coast of India are commercially and therapeutically interesting due to their various biological activities. These sugars were isolated from six (three red and three green) seaweed species using water at 100°C followed by precipitation using ethanol. The physical, chemical and biological characteristics were explored with specific highlights onto the specific rotation, HPLC-RI sugar speciation, antioxidant and antimicrobial activities. The biological properties were evaluated based on multiple methods and standards, such that the actual nature of the sugar is understood. G. corticata var. cylindrica (31.66%) had the highest sugar content. All the sugars had levo rotatory specific rotation and interesting chemical characteristics. Sugars isolated had competitive biological activities and had the presence of seven monosaccharides and one disaccharide. The results highlighted the socio-economic importance of seaweeds which could be developed as a potential source of bioactive compounds in the upcoming future. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optical Activity of Benzil Crystal

NASA Astrophysics Data System (ADS)

Říha, Jan; Vyšín, Ivo

2003-09-01

Optical activity of benzil as an example of optically active matter in the crystalline state only, not in solution, is studied for the wavelengths ranging from 0.320 m to 0.585 m. Previously measured experimental data are approximated by the theoretical set of formulas, which were derived by the use of the three coupled oscillators model. The earlier published formula consisting of six terms differed from the experimental data particularly in the wavelength region (0.380-0.510) m. This formula is replaced by the twelve-term formula which was computed by our specially worked computer program for the interpretation of the experimental data of optical activity based on the Marquardt-Levenberg method of the sum of least squares minimization. The possibility of molecular contribution to the resulting optical activity of benzil is mentioned. The use of Kramers-Kronig transforms for the determination of the circular dichroism curve based on the optical rotatory dispersion result is shown. The theoretically computed circular dichroism is compared with the available experimental data.

Determination of 2,4-dichlorophenoxyacetic acid and its major transformation product in soil samples by liquid chromatographic analysis.

PubMed

de Amarante, O P; Brito, N M; Dos Santos, T C R; Nunes, G S; Ribeiro, M L

2003-05-28

The 2,4-dichlorophenoxyacetic acid (2,4-D) is one of the most applied herbicides around the world to control broad leave herbs in many crops. In this study, a method was developed for simultaneous extraction and determination of 2,4-D and its major transformation product, i.e., the 2,4-dichlorophenol (2,4-DCP), in soil samples. The herbicide and its degradation product were extracted twice from soil samples, after acidification, by dichloromethane on ultrasound system for 1 h. Both extracts were combined and filtrated in qualitative filter paper and Celite((R)). The total extract was concentrated in rotatory evaporator, dried under N(2) and finally dissolved in 1 ml of methanol. High Performance Liquid Chromatography with UV detection at 230 nm was used for analysis. Recoveries were obtained from soil samples fortified at 0.1, 1.0, 2.0, 3.0 and 4.0 mgkg(-1) levels and the results varied from 85 to 111% (for 2,4-D) and from 95 to 98% (for 2,4-DCP). For both compounds, the limits of quantification were 0.1 mgkg(-1), which were the loss level at which the accuracy and the precision were studied. Nevertheless, the limits of detection, calculated by considering the blank standard deviation and the minimum concentration level, were 0.03 and 0.02 mgkg(-1), for 2,4-D and 2,4-DCP, respectively. This proposed method was applied to soil samples of eucalyptus crops, which was previously treated with the herbicide. Despite that, neither 2,4-D nor its degradation product were detected 30 days after the herbicide application.

Does Maximal External Tibial Component Rotation Influence Tibiofemoral Load Distribution in the Primary Knee Arthroplasty Setting: A Comparison of Neutral vs Maximal Anatomical External Rotatory States.

PubMed

Manning, William A; Ghosh, Kanishka M; Blain, Alasdair P; Longstaff, Lee M; Rushton, Steven P; Deehan, David J

2017-06-01

Tibial component rotation at time of knee arthroplasty can influence conformity, load transmission across the polyethylene surface, and perhaps ultimately determined survivorship. Optimal tibial component rotation on the cut surface is reliant on standard per operative manual stressing. This subjective assessment aims to balance constraint and stability of the articulation through a full arc of movement. Using a cadaveric model, computer navigation and under defined, previously validated loaded conditions mimicking the in vivo setting, the influence of maximal tibial component external rotation compared with the neutral state was examined for changes in laxity and tibiofemoral continuous load using 3D displacement measurement and an orthosensor continuous load sensor implanted within the polyethylene spacer in a simulated single radius total knee arthroplasty. No significant difference was found throughout arc of motion (0-115 degrees of flexion) for maximal varus and/or valgus or rotatory laxity between the 2 states. The neutral state achieved equivalence for mediolateral load distribution at each point of flexion. We have found that external rotation of the tibial component increased medial compartment load in comparison with the neutral position. Compared with the neutral state, external rotation consistently effected a marginal, but not significant reduction in lateral load under similar loading conditions. The effects were most pronounced in midflexion. On the basis of these findings, we would advocate for the midtibial tubercle point to determine tibial component rotation and caution against component external rotation. Copyright © 2017 Elsevier Inc. All rights reserved.

Toward a general mixed quantum/classical method for the calculation of the vibronic ECD of a flexible dye molecule with different stable conformers: Revisiting the case of 2,2,2-trifluoro-anthrylethanol.

PubMed

Cerezo, Javier; Aranda, Daniel; Avila Ferrer, Francisco J; Prampolini, Giacomo; Mazzeo, Giuseppe; Longhi, Giovanna; Abbate, Sergio; Santoro, Fabrizio

2018-06-01

We extend a recently proposed mixed quantum/classical method for computing the vibronic electronic circular dichroism (ECD) spectrum of molecules with different conformers, to cases where more than one hindered rotation is present. The method generalizes the standard procedure, based on the simple Boltzmann average of the vibronic spectra of the stable conformers, and includes the contribution of structures that sample all the accessible conformational space. It is applied to the simulation of the ECD spectrum of (S)-2,2,2-trifluoroanthrylethanol, a molecule with easily interconvertible conformers, whose spectrum exhibits a pattern of alternating positive and negative vibronic peaks. Results are in very good agreement with experiment and show that spectra averaged over all the sampled conformational space can deviate significantly from the simple average of the contributions of the stable conformers. The present mixed quantum/classical method is able to capture the effect of the nonlinear dependence of the rotatory strength on the molecular structure and of the anharmonic couplings among the modes responsible for molecular flexibility. Despite its computational cost, the procedure is still affordable and promises to be useful in all cases where the ECD shape arises from a subtle balance between vibronic effects and conformational variety. © 2018 Wiley Periodicals, Inc.

Rapid analysis of 2,4-D in soil samples by modified Soxhlet apparatus using HPLC with UV detection.

PubMed

Kashyap, Sanjay M; Pandya, Girish H; Kondawar, Vivek K; Gabhane, Sanjay S

2005-02-01

The 2,4-dichlorophenoxy acetic acid (2,4-D) is used as a systemic herbicide to control broadleaf weeds in wheat, corn, range land/pasture land, sorghum, and barley. In this study, a fast and efficient method is developed by selection of modified extraction apparatus and high-performance liquid chromatography (HPLC)-UV conditions for the determination of 2,4-D in soil samples. The method is applied to the study of soil samples collected from the agricultural field. The herbicide is extracted from soil samples by acetonitrile in a modified Soxhlet apparatus. The advantages of the apparatus are that it uses small volume of organic solvent, reduced time of extraction, and better recovery of the analyte. The extract is filtered using a very fine microfiber paper. The total extract is concentrated in a rotatory evaporator, dried under ultrahigh pure N2, and finally reconstituted in 1 mL of acetonitrile. HPLC-UV at 228 nm is used for analysis. The herbicide is identified and quantitated using the HPLC system. The method is validated by the analysis of spiked soil samples. Recoveries obtained varied from 85% to 100% for spiked soil samples. The limit of quantitation (LOQ) and the limit of detection (LOD) are 0.010 and 0.005 parts per million (ppm), respectively, for spiked soil samples. The LOQ and LOD are 0.006 and 0.003 ppm for unspiked soil samples. The measured concentrations of 2,4-D in spiked soil samples are between 0.010 and 0.020 ppm with an average of 0.016 +/- 0.003 ppm. For unspiked soil samples it is between 0.006 ppm and 0.012 ppm with an average of 0.009 +/- 0.002 ppm. The measured concentrations of 2,4-D in soil samples are generally low and do not exceed the regulatory agencies guidelines.

The role of arthroscopy in chronic elbow instability.

PubMed

Goodwin, David; Dynin, Maria; Macdonnell, J Ryan; Kessler, Michael W

2013-12-01

Elbow arthroscopy has had an emerging role in the management of many disorders of the elbow. In patients with chronic elbow instability, several arthroscopic techniques have been described in the diagnosis and management of posterolateral rotatory instability and valgus instability. We performed a systematic review investigating the role of arthroscopy in posterolateral rotatory instability and valgus instability in the elbow using the PubMed and CINAHL (Cumulative Index to Nursing and Allied Health Literature) databases, and the Cochrane Database of Systematic Reviews, consisting of articles from peer-reviewed journals published in the English language after January 1, 1991. Search criteria initially identified 249 articles. Twenty-five articles met criteria for inclusion. This included 17 review articles, 4 cadaveric studies, 3 retrospective studies, and 1 prospective study. Two of the retrospective studies compared arthroscopic and open techniques. Articles included in this systematic review concluded that arthroscopy is an accurate adjunct to physical examination and imaging in the diagnosis of chronic elbow instability and affords an exceptional view of the joint with the ability to address intra-articular pathologic conditions. Arthroscopic surgical techniques have shown equivalent clinical outcomes in a comparison of arthroscopic and open techniques. Elbow arthroscopy is a valuable tool in the diagnosis and management of chronic elbow instability. Patients treated arthroscopically benefit from additional diagnostic techniques, improved visualization of the elbow joint, the ability to address coexisting intra-articular pathologic conditions, and minimal soft tissue injury with no clinical consequences in outcomes. With such significant advantages, the use of elbow arthroscopy is likely to expand in the management of chronic elbow instability. Level IV, systematic review. Copyright © 2013 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Telemetered electromyography of the supinators and pronators of the forearm in gibbons and chimpanzees: implications for the fundamental positional adaptation of hominoids.

PubMed

Stern, J T; Larson, S G

2001-07-01

Extant apes are similar to one another, and different from monkeys, in features granting them greater range of forearm rotation and greater size of the muscles that produce this motion. Although these traits may have been independently acquired by the various apes, the possibility arises that such features reflect adaptation to the stem behavior of the hominoid lineage. Anticipating that knowledge of forearm rotatory muscle recruitment during brachiation, vertical climbing, arm-hanging during feeding, and voluntary reaching might point to this stem behavior, we undertook telemetered electromyographic experiments on the supinator, pronator quadratus, ulnar head of pronator teres, and a variety of other upper limb muscles in two gibbons and four chimpanzees. The primary rotator muscles of the hominoid forearm were recruited at high levels in a variety of behaviors. As had been suspected by previous researchers, the supinator is usually active during the support phase of armswinging, but we observed numerous instances of this behavior during which the muscle was inactive. No other muscle took over its role. Kinetic analyses are required to determine how apes can execute body rotation of armswinging without active muscular effort. The one behavior that is common to most extant apes, is rare in monkeys, and which places a consistently great demand on the primary forearm rotatory muscles, is hang-feeding. The muscles of the supporting limb are essential to properly position the body; those of the free limb are essential for grasping food. Since the greater range of forearm rotation characterizing apes is also best explained by adaptation to this behavior, we join previous authors who assert that it lies at the very origin of the Hominoidea. Copyright 2001 Wiley-Liss, Inc.

The video head impulse test during post-rotatory nystagmus: physiology and clinical implications.

PubMed

Mantokoudis, Georgios; Tehrani, Ali S Saber; Xie, Li; Eibenberger, Karin; Eibenberger, Bernhard; Roberts, Dale; Newman-Toker, David E; Zee, David S

2016-01-01

The aim of this study was to test the effects of a sustained nystagmus on the head impulse response of the vestibulo-ocular reflex (VOR) in healthy subjects. VOR gain (slow-phase eye velocity/head velocity) was measured using video head impulse test goggles. Acting as a surrogate for a spontaneous nystagmus (SN), a post-rotatory nystagmus (PRN) was elicited after a sustained, constant-velocity rotation, and then head impulses were applied. 'Raw' VOR gain, uncorrected for PRN, in healthy subjects in response to head impulses with peak velocities in the range of 150°/s-250°/s was significantly increased (as reflected in an increase in the slope of the gain versus head velocity relationship) after inducing PRN with slow phases of nystagmus of high intensity (>30°/s) in the same but not in the opposite direction as the slow-phase response induced by the head impulses. The values of VOR gain themselves, however, remained in the normal range with slow-phase velocities of PRN < 30°/s. Finally, quick phases of PRN were suppressed during the first 20-160 ms of a head impulse; the time frame of suppression depended on the direction of PRN but not on the duration of the head impulse. Our results in normal subjects suggest that VOR gains measured using head impulses may have to be corrected for any superimposed SN when the slow-phase velocity of nystagmus is relatively high and the peak velocity of the head movements is relatively low. The suppression of quick phases during head impulses may help to improve steady fixation during rapid head movements.

An electro-mechanical impedance model of a cracked composite beam with adhesively bonded piezoelectric patches

NASA Astrophysics Data System (ADS)

Yan, Wei; Cai, J. B.; Chen, W. Q.

2011-01-01

A model of a laminated composite beam including multiple non-propagating part-through surface cracks as well as installed PZT transducers is presented based on the method of reverberation-ray matrix (MRRM) in this paper. Toward determining the local flexibility characteristics induced by the individual cracks, the concept of the massless rotational spring is applied. A Timoshenko beam theory is then used to simulate the behavior of the composite beam with open cracks. As a result, transverse shear and rotatory inertia effects are included in the model. Only one-dimensional axial vibration of the PZT wafer is considered and the imperfect interfacial bonding between PZT patches and the host beam is further investigated based on a Kelvin-type viscoelastic model. Then, an accurate electro-mechanical impedance (EMI) model can be established for crack detection in laminated beams. In this model, the effects of various parameters such as the ply-angle, fibre volume fraction, crack depth and position on the EMI signatures are highlighted. Furthermore, comparison with existent numerical results is presented to validate the present analysis.

Mechanical Properties of a Primary Cilium Measured by Resonant Oscillation

NASA Astrophysics Data System (ADS)

Resnick, Andrew

Primary cilia are ubiquitous mammalian cellular substructures implicated in an ever-increasing number of regulatory pathways. The well-established `ciliary hypothesis' states that physical bending of the cilium (for example, due to fluid flow) initiates signaling cascades, yet the mechanical properties of the cilium remain incompletely measured, resulting in confusion regarding the biological significance of flow-induced ciliary mechanotransduction. In this work we measure the mechanical properties of a primary cilium by using an optical trap to induce resonant oscillation of the structure. Our data indicate 1), the primary cilium is not a simple cantilevered beam, 2), the base of the cilium may be modeled as a nonlinear rotatory spring, the linear spring constant `k' of the cilium base calculated to be (4.6 +/- 0.62)*10-12 N/rad and nonlinear spring constant ` α' to be (-1 +/- 0.34) *10-10 N/rad2 , and 3) the ciliary base may be an essential regulator of mechanotransduction signalling. Our method is also particularly suited to measure mechanical properties of nodal cilia, stereocilia, and motile cilia, anatomically similar structures with very different physiological functions.

Optical activity and electronic absorption spectra of some simple nucleosides related to cytidine and uridine: all-valence-shell molecular orbital calculations.

PubMed Central

Miles, D W; Redington, P K; Miles, D L; Eyring, H

1981-01-01

The circular dichroism and electronic absorption of three simple model systems for cytidine and uridine have been measured to 190 nm. The molecular spectral properties (excitation wavelengths, oscillator strengths, rotational strengths, and polarization directions) and electronic transitional patterns were investigated by using wave functions of the entire nucleoside with the goal of establishing the reliability of the theoretical method. The computed electronic absorption quantities were shown to be in satisfactory agreement with experimental data. It was found that the computed optical rotatory strengths of the B2u and E1u electronic transitions and lowest observed n-pi transition are in good agreement with experimental values. Electronic transitions were characterized by their electronic transitional patterns derived from population analysis of the transition density matrix. The theoretical rotational strengths associated with the B2u and E1u transitions stabilize after the use of just a few singly excited configurations in the configuration interaction basis and, hypothetically, are more reliable as indicators of conformation in pyrimidine nucleosides related to cytidine. PMID:6950393

The Intramolecular Hydrogen Bond N-H···S in 2,2'-Diaminodiphenyl Disulfide: Experimental and Computational Thermochemistry.

PubMed

Ramos, Fernando; Flores, Henoc; Hernández-Pérez, Julio M; Sandoval-Lira, Jacinto; Camarillo, E Adriana

2018-01-11

The intramolecular hydrogen bond of the N-H···S type has been investigated sparingly by thermochemical and computational methods. In order to study this interaction, the standard molar enthalpies of formation in gaseous phase of diphenyl disulfide, 2,2'-diaminodiphenyl disulfide and 4,4'-diaminodiphenyl disulfide at T = 298.15 K were determined by experimental thermochemical methods and computational calculations. The experimental enthalpies of formation in gas-phase were obtained from enthalpies of formation in crystalline phase and enthalpies of sublimation. Enthalpies of formation in crystalline phase were obtained using rotatory bomb combustion calorimetry. By thermogravimetry, enthalpies of vaporization were obtained, and by combining them with enthalpies of fusion, the enthalpies of sublimation were calculated. The Gaussian-4 procedure and the atomization method were applied to obtain enthalpies of formation in gas-phase of the compounds under study. Theoretical and experimental values are in good agreement. Through natural bond orbital (NBO) analysis and a topological analysis of the electronic density, the intramolecular hydrogen bridge (N-H···S) in the 2,2'-diaminodiphenyl disulfide was confirmed. Finally, an enthalpic difference of 11.8 kJ·mol -1 between the 2,2'-diaminodiphenyl disulfide and 4,4'-diaminodiphenyl disulfide was found, which is attributed to the intramolecular N-H···S interaction.

Cyanogen induced phosphorylation of D-fructose. [prebiotic modeling

NASA Technical Reports Server (NTRS)

Degani, CH.; Kawatsuji, M.; Halmann, M.

1975-01-01

It has been demonstrated that a phosphorylated sugar, identified as alpha-D-fructopyranose, can be formed as the result of cyanogen-induced phosphorylation of D-fructose at pH 8.8. The product was isolated from barium and cyclohexylammonium salts and identified on the basis of its chromatographic and electrophoretic properties, its lability to hydrolysis by alkaline phosphatase, the rate of its acid-catalyzed hydrolysis, and the results of periodate oxidation and optical rotatory measurements. These results support the suggestion that the cyanogen-induced phosphorylation of free sugars could be a possible process for formation of sugar phosphates under prebiotic conditions (Halman et al., 1969).

Experiments on the origin of molecular chirality by parity non-conservation during beta-decay

NASA Technical Reports Server (NTRS)

Bonner, W. A.

1974-01-01

Experiments are described to test a theory for the origin of optical activity wherein the longitudinally polarized electrons resulting from parity violation during radioactive beta-decay, and their resulting circularly polarized bremsstrahlung, might interact asymmetrically with organic matter to yield optically active products. The historical background to this subject is briefly reviewed. Our experiments involve subjecting a number of racemic and optically active amino acid samples to a beta-radiation source for a period of 1.34 years (total dose: 411 Mrads), then examining them for any asymmetric effects by means of optical rotatory dispersion and analytical gas chromatography.

Hormetic Effect of Chronic Hypergravity in a Mouse Model of Allergic Asthma and Rhinitis

NASA Astrophysics Data System (ADS)

Jang, Tae Young; Jung, Ah-Yeoun; Kim, Young Hyo

2016-06-01

We aimed to evaluate the effect of chronic hypergravity in a mouse model of allergic asthma and rhinitis. Forty BALB/c mice were divided as: group A (n = 10, control) sensitized and challenged with saline, group B (n = 10, asthma) challenged by intraperitoneal and intranasal ovalbumin (OVA) to induce allergic asthma and rhinitis, and groups C (n = 10, asthma/rotatory control) and D (n = 10, asthma/hypergravity) exposed to 4 weeks of rotation with normogravity (1G) or hypergravity (5G) during induction of asthma/rhinitis. Group D showed significantly decreased eosinophils, neutrophils, and lymphocytes in their BAL fluid compared with groups B and C (p < 0.05). In real-time polymerase chain reaction using lung homogenate, the expression of IL-1β was significantly upregulated (p < 0.001) and IL-4 and IL-10 significantly downregulated (p < 0.05) in group D. Infiltration of inflammatory cells into lung parenchyma and turbinate, and the thickness of respiratory epithelium was significantly reduced in group D (p < 0.05). The expression of Bcl-2 and heme oxygenase-1 were significantly downregulated, Bax and extracellular dismutase significantly upregulated in Group D. Therefore, chronic hypergravity could have a hormetic effect for allergic asthma and rhinitis via regulation of genes involved in antioxidative and proapoptotic pathways. It is possible that we could use hypergravity machinery for treating allergic respiratory disorders.

Magneto-encephalographic measurement of neural activity during period of vertigo induced by cold caloric stimulation.

PubMed

Kandori, Akihiko; Oe, Hiroshi; Miyashita, Kotaro; Ohira, Shinji; Naritomi, Hiroaki; Chiba, Yoshihide; Ogata, Kuniomi; Murakami, Masahiro; Miyashita, Tsuyoshi; Tsukada, Keiji

2003-07-01

The aim of this study was to investigate neural activity during period of vertiginous sensation, induced by caloric stimulation. After caloric vestibular stimulation (CVS) by cold water of five volunteers (n=5, age: 30+/-10), auditory evoked magnetic fields (AEFs) during the subsequent period of vertiginous sensations were measured by magnetoencephalography (MEG). Current-arrow maps (CAMs) were produced to estimate the spatial current distribution of the AEF responses, and a rotation value (dI(rot)) was calculated from the CAM. The worth of the dI(rot) values as indicators of vertigo was evaluated by comparing them with earlier reported values for elderly control (n=11, age: 67+/-5) and chronic dizziness (CD) (n=27, age: 68+/-8) groups (obtained from AEF responses with no the CVS). Although all volunteers felt vertigo during the AEF measurements, the AEF waveforms and CAM pattern only showed slight changes. While the dI(rot) values (1.43+/-0.73) just after CVS were not significantly different from those (1.59+/-0.46) for the elderly controls, they were significantly different from those (3.54+/-1.34) for the CD patients. These findings suggest that (i) the new parameter (dI(rot)) is more sensitively indicates dizziness (non-rotatory sensation) than vertigo (ii) the auditory cortical region may play an important role in body-balance perception of floating sensations.

Comparison of in situ forces and knee kinematics in anteromedial and high anteromedial bundle augmentation for partially ruptured anterior cruciate ligament.

PubMed

Xu, Yan; Liu, Jianyu; Kramer, Scott; Martins, Cesar; Kato, Yuki; Linde-Rosen, Monica; Smolinski, Patrick; Fu, Freddie H

2011-02-01

High tunnel placement is common in single- and double-bundle anterior cruciate ligament (ACL) reconstructions. Similar nonanatomic tunnel placement may also occur in ACL augmentation surgery. In this study, in situ forces and knee kinematics were compared between nonanatomic high anteromedial (AM) and anatomic AM augmentation in a knee with isolated AM bundle injury. Controlled laboratory study. Seven fresh-frozen cadaver knees were used (age, 48 ± 12.5 years). First, intact knee kinematics was tested with a robotic-universal force sensor testing system under 2 loading conditions. An 89-N anterior load was applied, and an anterior tibial translation was measured at knee flexion angles of 0°, 30°, 60°, and 90°. Then, combined rotatory loads of 7-N·m valgus and 5-N·m internal tibial rotation were applied at 15° and 30° of knee flexion angles, which mimic the pivot shift. Afterward, only the AM bundle of the ACL was cut arthroscopically, keeping the posterolateral bundle intact. The knee was again tested using the intact knee kinematics to measure the in situ force of the AM bundle. Then, arthroscopic anatomic AM bundle reconstruction was performed with an allograft, and the knee was tested to give the in situ force of the reconstructed AM bundle. Knee kinematics under the 3 conditions (intact, anatomic AM augmentation, and nonanatomic high AM augmentation) and the in situ force were compared and analyzed. The high AM graft had significantly lower in situ force than the intact and anatomic reconstructed AM bundle at 0° of knee flexion (P < .05) and the intact AM bundle at 30° of knee flexion under anterior tibial loading. There were no differences between anatomic graft and intact AM bundle. The high AM graft also had a significantly lower in situ force than the intact and anatomic reconstructed AM with simulated pivot-shift loading at 15° and 30° of flexion (P < .05). Under anterior tibial and rotatory loading, there was a difference in tibial displacement between anatomic and high AM reconstructions and between the high AM graft and intact ACL under rotational loading with the knee at 15° of flexion. Anatomic AM augmentation can lead to biomechanical advantages at time zero when compared with the nonanatomic (high AM) augmentation. Anatomic AM augmentation better restores the knee kinematics to the intact ACL state.

[Effect of activation and blockade of the GABA-ergic system of the substantia nigra in the midbrain on the realization of conditioned food reflexes in dogs].

PubMed

Iakimovskiĭ, A F

1988-01-01

Bilateral injection of 45 mcg of GABA into substantia nigra pars compacta produced in dogs a manifested improvement of parameters of the conditioned differentiation inhibition but failed to influence the positive Pavlovian alimentary conditioned reflex. Injection of GABA synaptic antagonist--picrotoxin impaired conditioned alimentary behaviour. Numerous injections of the GABAergic pharmacological agents resulted in motor disturbance--rotatory movements--and skin trophic deviations. The data obtained and literature references give ground for discussion of the role of striato-nigral and internal GABAergic substantia nigra systems in the positive modulation of adaptive alimentary behaviour and conditioned stimuli differentiation.

Variational theorems for superimposed motions in elasticity, with application to beams

NASA Technical Reports Server (NTRS)

Doekmeci, M. C.

1976-01-01

Variational theorems are presented for a theory of small motions superimposed on large static deformations and governing equations for prestressed beams on the basis of 3-D theory of elastodynamics. First, the principle of virtual work is modified through Friedrichs's transformation so as to describe the initial stress problem of elastodynamics. Next, the modified principle together with a chosen displacement field is used to derive a set of 1-D macroscopic governing equations of prestressed beams. The resulting equations describe all the types of superimposed motions in elastic beams, and they include all the effects of transverse shear and normal strains, and the rotatory inertia. The instability of the governing equations is discussed briefly.

Si@void@C Nanofibers Fabricated Using a Self-Powered Electrospinning System for Lithium-Ion Batteries.

PubMed

Han, Yu; Zou, Jingdian; Li, Zhen; Wang, Wenqiang; Jie, Yang; Ma, Jinming; Tang, Bin; Zhang, Qi; Cao, Xia; Xu, Shengming; Wang, Zhong Lin

2018-05-22

In recent years, research in lithium-ion batteries (LIBs) has been focused on improving their performance in various ways, such as density, capacity, and lifetime, but little attention has been paid to the energy consumption cost in the manufacturing process. Herein, we report an energy-efficient preparation method of anode materials for LIBs based on a self-powered electrospinning system without an external power source, which consists of a rotatory triboelectric nanogenerator (r-TENG), a power management circuit, and an electrospinning unit. By harvesting kinetic energy from a handle rotation, the r-TENG is able to fully power the electrospinning system to fabricate nanofibers for LIBs. The as-obtained Si@void@C nanofibers present outstanding cyclic performance with a discharge capacity of 1045.2 mA h g -1 after 100 cycles and 88% capacity retention, along with an excellent high rate capacity of 400 mA h g -1 at a current density of 5 A g -1 , which are completely comparable with those made by commercial electrospinning equipment. Our study demonstrates an innovative and distinct approach toward an extremely low-cost preparation procedure of electrode materials, leading to a great breakthrough for the LIB production industry.

A low-cost video-oculography system for vestibular function testing.

PubMed

Jihwan Park; Youngsun Kong; Yunyoung Nam

2017-07-01

In order to remain in focus during head movements, vestibular-ocular reflex causes eyes to move in the opposite direction to head movement. Disorders of vestibular system decrease vision, causing abnormal nystagmus and dizziness. To diagnose abnormal nystagmus, various studies have been reported including the use of rotating chair tests and videonystagmography. However, these tests are unsuitable for home use due to their high costs. Thus, a low-cost video-oculography system is necessary to obtain clinical features at home. In this paper, we present a low-cost video-oculography system using an infrared camera and Raspberry Pi board for tracking the pupils and evaluating a vestibular system. Horizontal eye movement is derived from video data obtained from an infrared camera and infrared light-emitting diodes, and the velocity of head rotation is obtained from a gyroscope sensor. Each pupil was extracted using a morphology operation and a contour detection method. Rotatory chair tests were conducted with our developed device. To evaluate our system, gain, asymmetry, and phase were measured and compared with System 2000. The average IQR errors of gain, phase and asymmetry were 0.81, 2.74 and 17.35, respectively. We showed that our system is able to measure clinical features.

Endodontic treatment of mandibular molar with root dilaceration using Reciproc single-file system.

PubMed

Meireles, Daniely Amorin; Bastos, Mariana Mena Barreto; Marques, André Augusto Franco; Garcia, Lucas da Fonseca Roberti; Sponchiado, Emílio Carlos

2013-08-01

Biomechanical preparation of root canals with accentuated curvature is challenging. New rotatory systems, such as Reciproc, require a shorter period of time to prepare curved canals, and became a viable alternative for endodontic treatment of teeth with root dilaceration. Thus, this study aimed to report a clinical case of endodontic therapy of root with accentuated dilaceration using Reciproc single-file system. Mandibular right second molar was diagnosed as asymptomatic irreversible pulpitis. Pulp chamber access was performed, and glide path was created with #10 K-file (Dentsply Maillefer) and PathFile #13, #16 and #19 (Dentsply Maillefer) up to the temporary working length. The working length measured corresponded to 20 mm in the mesio-buccal and mesio-lingual canals, and 22 mm in the distal canal. The R25 file (VDW GmbH) was used in all the canals for instrumentation and final preparation, followed by filling with Reciproc gutta-percha cones (VDW GmbH) and AH Plus sealer (Dentsply Maillefer), using thermal compaction technique. The case has been receiving follow-up for 6 mon and no painful symptomatology or periapical lesions have been found. Despite the difficulties, the treatment could be performed in a shorter period of time than the conventional methods.

Optical Rotatory Dispersion: New Twists on AN Old Topic

NASA Astrophysics Data System (ADS)

Vaccaro, Patrick

2017-06-01

Among the many physicochemical properties used to distinguish chiral molecules, perhaps none has had as profound and sustained an impact in the realm of chemistry as the characteristic interactions that take place with polarized light. Of special note is the dispersive (non-resonant) phenomenon of circular birefringence (CB), the manifestation of which first was reported over two centuries ago and which still is employed routinely - in the more familiar guise of specific optical rotation - to gauge the enantiomeric purity of the products emerging from asymmetric syntheses. Concerted experimental and theoretical efforts designed to probe such electronic optical activity in isolated chiral molecules will be presented, with special emphasis directed towards the marked influence that intramolecular (vibrational and conformational) dynamics and intermolecular (environmental) perturbations can exert upon the intrinsic chiroptical response. Requisite isolated-molecule measurements have been made possible by our continuing development of cavity ring-down polarimetry (CRDP), an ultrasensitive polarimetric scheme that has permitted the first quantitative analyses of optical rotatory dispersion (ORD or wavelength-resolved CB) to be performed in rarefied (gaseous) media. Various technical aspects of CRDP will be discussed to illustrate the unique capabilities and practical limitations afforded by this novel methodology. Comparison of specific rotation values acquired for a broad spectrum of rigid and flexible chiral species under complementary isolated and solvated conditions will highlight the intimate coupling that exists among electronic and nuclear degrees of freedom as well as the pronounced, yet oftentimes counterintuitive, effects incurred by subtle solute-solvent interactions. The disparate nature of optical activity extracted from different surroundings will be demonstrated, with quantum-chemical calculations serving to elucidate the structural, electronic, and environmental provenance of observed behavior. In addition to unraveling basic processes that mediate chiroptical response in condensed media, the vapor-phase ORD benchmarks resulting from these studies afford a critical assessment for computational predictions of dispersive optical activity and for their burgeoning ability to assist in the assignment of absolute stereochemical configuration.

Studies of Cell-Mediated Immunity Against Immune Disorders Using Synthetic Peptides and Rotating Bioreactor System

NASA Technical Reports Server (NTRS)

Sastry, Jagannadha K.

1997-01-01

Our proposed experiments included: (1) immunzing mice with synthetic peptides; (2) preparing spleen and lymph node cells; (3) growing them under conventional conditions as well as in the rotatory vessel in appropriate medium reconstituting with synthetic peptides and/or cytokines as needed; and (4) comparing at regular time intervals the specific CTL activity as well as helper T-cell activity (in terms of both proliferative responses and cytokine production) using established procedures in my laboratory. We further proposed that once we demonstrated the merit of rotatory vessel technology to achieve desired results, these studies would be expanded to include immune cells from non-human primates (rhesus monkeys and chimpanzees) and also humans. We conducted a number of experiments to determine CTL induction by the synthetic peptides corresponding to antigenic proteins in HIV and HPV in different mouse strains that express MHC haplotypes H-2b or H-2d. We immunized mice with 100 ug of the synthetic peptide, suspended in sterile water, and emulsified in CFA (1:1). The immune lymph node cells obtained after 7 days were restimulated by culturing in T25 flask, HARV-10, or STLV-50, in the presence of the peptide at 20 ug/ml. The results from the 5'Cr-release assay consistently revealed complete abrogation of CTL activity of cells grown in the bioreactors (both HARV and STLV), while significant antigen-specific CTL activity was observed with cells cultured in tissue culture flasks. Thus, overall the data we generated in this study proved the usefulness of the NASA-developed developed technology for understanding the known immune deficiency during space travel. Additionally, this ex vivo microgravity technology since it mimics effectively the in vivo situation, it is also useful in understanding immune disorders in general. Thus, our proposed studies in TMC-NASA contract round II application benefit from data generated in this TMC-NASA contract round I study.

Tilt perception during dynamic linear acceleration.

PubMed

Seidman, S H; Telford, L; Paige, G D

1998-04-01

Head tilt is a rotation of the head relative to gravity, as exemplified by head roll or pitch from the natural upright orientation. Tilt stimulates both the otolith organs, owing to shifts in gravitational orientation, and the semicircular canals in response to head rotation, which in turn drive a variety of behavioral and perceptual responses. Studies of tilt perception typically have not adequately isolated otolith and canal inputs or their dynamic contributions. True tilt cannot readily dissociate otolith from canal influences. Alternatively, centrifugation generates centripetal accelerations that simulate tilt, but still entails a rotatory (canal) stimulus during important periods of the stimulus profiles. We reevaluated the perception of head tilt in humans, but limited the stimulus to linear forces alone, thus isolating the influence of otolith inputs. This was accomplished by employing a centrifugation technique with a variable-radius spinning sled. This allowed us to accelerate the sled to a constant angular velocity (128 degrees/s), with the subject centered, and then apply dynamic centripetal accelerations after all rotatory perceptions were extinguished. These stimuli were presented in the subjects' naso-occipital axis by translating the subjects 50 cm eccentrically either forward or backward. Centripetal accelerations were thus induced (0.25 g), which combined with gravity to yield a dynamically shifting gravitoinertial force simulating pitch-tilt, but without actually rotating the head. A magnitude-estimation task was employed to characterize the dynamic perception of pitch-tilt. Tilt perception responded sluggishly to linear acceleration, typically reaching a peak after 10-30 s. Tilt perception also displayed an adaptation phenomenon. Adaptation was manifested as a per-stimulus decline in perceived tilt during prolonged stimulation and a reversal aftereffect upon return to zero acceleration (i.e., recentering the subject). We conclude that otolith inputs can produce tilt perception in the absence of canal stimulation, and that this perception is subject to an adaptation phenomenon and low-pass filtering of its otolith input.

Effects of special exercise programs on functional movement screen scores and injury prevention in preprofessional young football players.

PubMed

Dinc, Engin; Kilinc, Bekir Eray; Bulat, Muge; Erten, Yunus Turgay; Bayraktar, Bülent

2017-10-01

To increase movement capacity and to reduce injury risk in young soccer players by implementing a special functional exercise program based on functional movement screen (FMS) and correctives. 67 young male athletes 14-19 years of age from a Super League Football Club Academy participated in the study. Functional movement patterns were evaluated with FMS assessment protocol. Deep squat, hurdle step, inline lunge, shoulder mobility, active straight leg raise, trunk stability push-up, and rotatory stability were examined in FMS. Considering the FMS scores the number of intervention and control groups were defined as 24 and 43, respectively. Intervention program was composed of 1 hr twice a week sessions in total of 12 weeks with 4 weeks of mobility, 4 weeks of stability, and 4 weeks of integration exercises. At the end of 12-week intervention and control groups were re-evaluated with FMS protocol. Contact and noncontact sports injuries recorded during one season. In intervention group there was statistically significant difference in increase in total FMS scores ( P <0.01), deep squat ( P ≤0.001), hurdle step ( P <0.05), inline lunge ( P <0.01), and trunk stability push-up ( P <0.01). In control group total FMS, deep squat, and trunk stability push-up scores increased with a statistical difference ( P <0.01, P <0.05, P ≤0.01, respectively). The incidence of noncontact injury in control group was higher than intervention group ( P <0.05). Periodic movement screening and proper corrections with functional training is valuable in order to create better movement capacity to build better physical performance and more effective injury prevention.

Uniform stable observer for the disturbance estimation in two renewable energy systems.

PubMed

Rubio, José de Jesús; Ochoa, Genaro; Balcazar, Ricardo; Pacheco, Jaime

2015-09-01

In this study, an observer for the states and disturbance estimation in two renewable energy systems is introduced. The restrictions of the gains in the proposed observer are found to guarantee its stability and the convergence of its error; furthermore, these results are utilized to obtain a good estimation. The introduced technique is applied for the states and disturbance estimation in a wind turbine and an electric vehicle. The wind turbine has a rotatory tower to catch the incoming air to be transformed in electricity and the electric vehicle has generators connected with its wheels to catch the vehicle movement to be transformed in electricity. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Dynamic stability of unidirectional fiber-reinforced viscoelastic composite plates

NASA Technical Reports Server (NTRS)

Chandiramani, N. K.; Librescu, L.

1989-01-01

This paper deals with a dynamic stability analysis of unidirectional fiber-reinforced composite viscoelastic plates subjected to compressive edge loads. The integrodifferential equations governing the stability problem are obtained by using, in conjunction with a Boltzmann hereditary constitutive law for a three-dimensional viscoelastic medium, a higher-order shear deformation theory of orthotropic plates. Such a theory incorporates transverse shear deformation, transverse normal stress, and rotatory inertia effects. The solution of the stability problem as considered within this paper concerns the determination of the critical in-plane edge loads yielding the asymptotic instability. Numerical applications, based on material properties derived within the framework of Aboudi's micromechanical model, are presented and pertinent conclusions concerning the nature of the loss of stability and the influence of various parameters are outlined.

New Design for Rapid Prototyping of Digital Master Casts for Multiple Dental Implant Restorations

PubMed Central

Romero, Luis; Jiménez, Mariano; Espinosa, María del Mar; Domínguez, Manuel

2015-01-01

Aim This study proposes the replacement of all the physical devices used in the manufacturing of conventional prostheses through the use of digital tools, such as 3D scanners, CAD design software, 3D implants files, rapid prototyping machines or reverse engineering software, in order to develop laboratory work models from which to finish coatings for dental prostheses. Different types of dental prosthetic structures are used, which were adjusted by a non-rotatory threaded fixing system. Method From a digital process, the relative positions of dental implants, soft tissue and adjacent teeth of edentulous or partially edentulous patients has been captured, and a maser working model which accurately replicates data relating to the patients oral cavity has been through treatment of three-dimensional digital data. Results Compared with the conventional master cast, the results show a significant cost savings in attachments, as well as an increase in the quality of reproduction and accuracy of the master cast, with the consequent reduction in the number of patient consultation visits. The combination of software and hardware three-dimensional tools allows the optimization of the planning of dental implant-supported rehabilitations protocol, improving the predictability of clinical treatments and the production cost savings of master casts for restorations upon implants. PMID:26696528

The necessity of clinical application of tibial reduction for detection of underestimated posterolateral rotatory instability in combined posterior cruciate ligament and posterolateral corner deficient knee.

PubMed

Lee, Han-Jun; Park, Yong-Beom; Ko, Young-Bong; Kim, Seong-Hwan; Kwon, Hyeok-Bin; Yu, Dong-Seok; Jung, Young-Bok

2015-10-01

The purpose of this study was to evaluate the usefulness of tibial reduction during dial test for clinical detection of underestimated posterolateral rotatory instability (PLRI) in combined posterior cruciate ligament (PCL)-posterolateral corner (PLC) deficient knee in terms of external rotation laxity and clinical outcomes. Twenty-one patients who classified as grade I PLRI using dial test with subluxated tibia, but classified as grade II with tibial reduction evaluated retrospectively. The mean follow-up was 39.3 months (range 24-61 months). Each patient was evaluated by the following variables: posterior translation and varus laxity on radiograph, KT-1000 arthrometer, dial test (reduced and subluxated position), International Knee Documentation Committee, Orthopädische Arbeitsgruppe Knie scoring system and Tegner activity scale. There were significant improvements in posterior tibial translation (8.6 ± 2.0 to 2.1 ± 1.0 mm; P < 0.001), varus laxity (3.3 ± 1.3 to 1.4 ± 0.5 mm; P < 0.001) and external rotation (13.2° ± 0.8° to 3.6° ± 1.1° at 30°, 13.3° ± 0.9° to 3.6° ± 0.9° at 90°; P < 0.001). The clinical scores were improved significantly at the last follow-up (P < 0.001). The external tibial rotation during dial test with tibial reduction increased from 6.8° ± 0.9 to 13.2° ± 0.8° at 30° of knee flexion, from 7.0° ± 0.8° to 13.3° ± 0.9° at 90° (P < 0.001). The clinical application of reduction of posteriorly subluxated tibia during the dial test was essential for an appropriate treatment of underestimated PLRI in combined PCL-PLC deficient knee. Retrospective case series, Level IV.

Articular Contact Area and Pressure in Posteromedial Rotatory Instability of the Elbow.

PubMed

Bellato, Enrico; Fitzsimmons, James S; Kim, Youngbok; Bachman, Daniel R; Berglund, Lawrence J; Hooke, Alexander W; O'Driscoll, Shawn W

2018-03-21

Joint incongruity in posteromedial rotatory instability (PMRI) has been theorized to determine early articular degenerative changes. Our hypothesis was that the articular contact area and contact pressure differ significantly between an intact elbow and an elbow affected by PMRI. Seven cadaveric elbows were tested under gravity varus stress using a custom-made machine designed to simulate muscle loads and allow passive elbow flexion (0° to 90°). The mean contact area and contact pressure data were collected and processed using the Tekscan sensor and software. After testing the intact specimen (intact elbow), a PMRI injury was simulated (PMRI elbow) and the specimen was tested again. The PMRI elbows were characterized by initial joint subluxation and significantly elevated articular contact pressure. Both worsened, corresponding with a reduction in contact area, as the elbow was flexed from 0° until the joint subluxation and incongruity spontaneously reduced (at a mean [and standard error] of 60° ± 5° of flexion), at which point the mean contact pressure decreased from 870 ± 50 kPa (pre-reduction) to 440 ± 40 kPa (post-reduction) (p < 0.001) and the mean contact area increased from 80 ± 8 mm to 150 ± 58 mm (p < 0.001). This reduction of the subluxation was also followed by a shift of the contact area from the coronoid fracture edge toward the lower portion of the coronoid. At the flexion angle at which the PMRI elbows reduced, both the contact area and the contact pressure of the intact elbows differed significantly from those of the PMRI elbows, both before and after the elbow reduction (p < 0.001). The reduction in contact area and increased contact pressures due to joint subluxation and incongruity could explain the progressive arthritis seen in some elbows affected by PMRI. This biomechanical study suggests that the early degenerative changes associated with PMRI reported in the literature could be subsequent to joint incongruity and an increase in contact pressure between the coronoid fracture surface and the trochlea.

Anatomic and Histological Investigation of the Anterolateral Capsular Complex in the Fetal Knee.

PubMed

Sabzevari, Soheil; Rahnemai-Azar, Amir Ata; Albers, Marcio; Linde, Monica; Smolinski, Patrick; Fu, Freddie H

2017-05-01

There is currently disagreement with regard to the presence of a distinct ligament in the anterolateral capsular complex of the knee and its role in the pivot-shift mechanism and rotatory laxity of the knee. To investigate the anatomic and histological properties of the anterolateral capsular complex of the fetal knee to determine whether there exists a distinct ligamentous structure running from the lateral femoral epicondyle inserting into the anterolateral tibia. Descriptive laboratory study. Twenty-one unpaired, fresh fetal lower limbs, gestational age 18 to 22 weeks, were used for anatomic investigation. Two experienced orthopaedic surgeons performed the anatomic dissection using loupes (magnification ×3.5). Attention was focused on the anterolateral and lateral structures of the knee. After the skin and superficial fascia were removed, the iliotibial band was carefully separated from underlying structures. The anterolateral capsule was then examined under internal and external rotation and varus-valgus manual loading and at different knee flexion angles for the presence of any ligamentous structures. Eight additional unpaired, fetal lower limbs, gestational age 11 to 23 weeks, were used for histological analysis. This study was not able to prove the presence of a distinct capsular or extracapsular ligamentous structure in the anterolateral capsular complex area. The presence of the fibular collateral ligament, a distal attachment of the biceps femoris, the entire lateral capsule, the iliotibial band, and the popliteus tendon in the anterolateral and lateral area of the knee was confirmed in all the samples. Histological analysis of the anterolateral capsule revealed a loose, hypocellular connective tissue with less organized collagen fibers compared with ligament and tendinous structures. The main finding of this study was that the presence of a distinct ligamentous structure in the anterolateral complex is not supported from a developmental point of view, while all other anatomic structures were present. The inability to prove the existence of a distinct ligamentous structure, called the anterolateral ligament, in the anterolateral knee capsule may indicate that the other components of the anterolateral complex, such as the lateral capsule, the iliotibial band, and its capsule-osseous layer, are more important for knee rotatory stability.

Clinical evaluation of acute phase nystagmus associated with cerebellar lesions.

PubMed

Ogawa, Y; Otsuka, K; Hagiwara, A; Inagaki, T; Shimizu, S; Nagai, N; Konomi, U; Itani, S; Kondo, T; Suzuki, M

2016-06-01

To determine the characteristics of acute phase nystagmus in patients with cerebellar lesions, and to identify a useful indicator for differentiating central lesions from peripheral lesions. Acute phase nystagmus and the appearance of neurological symptoms were retrospectively investigated in 11 patients with cerebellar stroke. At the initial visit, there were no patients with vertical nystagmus, direction-changing gaze evoked nystagmus or pure rotatory nystagmus. There were four cases with no nystagmus and seven cases with horizontal nystagmus at the initial visit. There were no neurological symptoms, except for vertigo and hearing loss, in any cases at the initial visit. The direction and type of nystagmus changed with time, and neurological symptoms other than vertigo appeared subsequently to admission. It is important to observe the changes in nystagmus and other neurological findings for the differential diagnosis of central lesions.

A new chiral residue analysis method for triazole fungicides in water using dispersive liquid-liquid microextraction (DLLME).

PubMed

Luo, Mai; Liu, Donghui; Zhou, Zhiqiang; Wang, Peng

2013-09-01

A rapid, simple, reliable, and environment-friendly method for the residue analysis of the enantiomers of four chiral fungicides including hexaconazole, triadimefon, tebuconazole, and penconazole in water samples was developed by dispersive liquid-liquid microextraction (DLLME) pretreatment followed by chiral high-performance liquid chromatography (HPLC)-DAD detection. The enantiomers were separated on a Chiralpak IC column by HPLC applying n-hexane or petroleum ether as mobile phase and ethanol or isopropanol as modifier. The influences of mobile phase composition and temperature on the resolution were investigated and most of the enantiomers could be completely separated in 20 min under optimized conditions. The thermodynamic parameters indicated that the separation was enthalpy-driven. The elution orders were detected by both circular dichroism detector (CD) and optical rotatory dispersion detector (ORD). Parameters affecting the DLLME performance for pretreatment of the chiral fungicides residue in water samples, such as the extraction and dispersive solvents and their volume, were studied and optimized. Under the optimum microextraction condition the enrichment factors were over 121 and the linearities were 30-1500 µg L(-1) with the correlation coefficients (R(2)) over 0.9988 and the recoveries were between 88.7% and 103.7% at the spiking levels of 0.5, 0.25, and 0.05 mg L(-1) (for each enantiomer) with relative standard deviations varying from 1.38% to 6.70% (n = 6) The limits of detection (LODs) ranged from 8.5 to 29.0 µg L(-1) (S/N = 3). © 2013 Wiley Periodicals, Inc.

Femtosecond characterization of vibrational optical activity of chiral molecules.

PubMed

Rhee, Hanju; June, Young-Gun; Lee, Jang-Soo; Lee, Kyung-Koo; Ha, Jeong-Hyon; Kim, Zee Hwan; Jeon, Seung-Joon; Cho, Minhaeng

2009-03-19

Optical activity is the result of chiral molecules interacting differently with left versus right circularly polarized light. Because of this intrinsic link to molecular structure, the determination of optical activity through circular dichroism (CD) spectroscopy has long served as a routine method for obtaining structural information about chemical and biological systems in condensed phases. A recent development is time-resolved CD spectroscopy, which can in principle map the structural changes associated with biomolecular function and thus lead to mechanistic insights into fundamental biological processes. But implementing time-resolved CD measurements is experimentally challenging because CD is a notoriously weak effect (a factor of 10(-4)-10(-6) smaller than absorption). In fact, this problem has so far prevented time-resolved vibrational CD experiments. Here we show that vibrational CD spectroscopy with femtosecond time resolution can be realized when using heterodyned spectral interferometry to detect the phase and amplitude of the infrared optical activity free-induction-decay field in time (much like in a pulsed NMR experiment). We show that we can detect extremely weak signals in the presence of large achiral background contributions, by simultaneously measuring with a femtosecond laser pulse the vibrational CD and optical rotatory dispersion spectra of dissolved chiral limonene molecules. We have so far only targeted molecules in equilibrium, but it would be straightforward to extend the method for the observation of ultrafast structural changes such as those occurring during protein folding or asymmetric chemical reactions. That is, we should now be in a position to produce 'molecular motion pictures' of fundamental molecular processes from a chiral perspective.

Burnishing of rotatory parts to improve surface quality

NASA Astrophysics Data System (ADS)

Celaya, A.; López de Lacalle, L. N.; Albizuri, J.; Alberdi, R.

2009-11-01

In this paper, the use of rolling burnishing process to improve the final quality of railway and automotive workpieces is studied. The results are focused on the improvement of the manufacturing processes of rotary workpieces used in railway and automotion industry, attending to generic target of achieving `maximum surface quality with minimal process time'. Burnishing is a finishing operation in which plastic deformation of surface irregularities occurs by applying pressure through a very hard element, a roller or a ceramic ball. This process gives additional advantages to the workpiece such as good surface roughness, increased hardness and high compressive residual stresses. The effect of the initial turning conditions on the final burnishing operation has also been studied. The results show that feeds used in the initial rough turning have little influence in the surface finish of the burnished workpieces. So, the process times of the combined turning and burnishing processes can be reduced, optimizing the shaft's machining process.

Impact buckling of thin bars in the elastic range for any end condition

NASA Technical Reports Server (NTRS)

Taub, Josef

1934-01-01

Following a qualitative discussion of the complicated process involved in a short-period, longitudinal force applied to an originally not quite straight bar, the actual process is substituted by an idealized process for the purpose of analytical treatment. The simplifications are: the assumption of an infinitely high rate of propagation of the elastic longitudinal waves in the bar, limitation to slender bars, disregard of material damping and of rotatory inertia, the assumption of consistently small elastic deformations, the assumption of cross-sectional dimensions constant along the bar axis, the assumption of a shock-load constant in time, and the assumption of eccentricities on one plane. Then follow the mathematical principles for resolving the differential equation of the simplified problem, particularly the developability of arbitrary functions with steady first and second and intermittently steady third and fourth derivatives into one convergent series, according to the natural functions of the homogeneous differential equation.

Stability toward High Energy Radiation of Non-Proteinogenic Amino Acids: Implications for the Origins of Life

PubMed Central

Cataldo, Franco; Iglesias-Groth, Susana; Angelini, Giancarlo; Hafez, Yaser

2013-01-01

A series of non-proteinogenic amino acids, most of them found quite commonly in the meteorites known as carbonaceous chondrites, were subjected to solid state radiolysis in vacuum to a total radiation dose of 3.2 MGy corresponding to 23% of the total dose expected to be taken by organic molecules buried in asteroids and meteorites since the beginning of the solar system 4.6 × 109 years ago. The radiolyzed amino acids were studied by FT-IR spectroscopy, Differential Scanning Calorimetry (DSC) and by polarimety and Optical Rotatory Dispersion (ORD). It is shown that an important fraction of each amino acid is able to “survive” the massive dose of radiation, while the enantiomeric excess is partially preserved. Based on the results obtained, it is concluded that it is unsurprising to find amino acids even in enantiomeric excess in carbonaceous chondrites. PMID:25369815

Anatomical Individualized ACL Reconstruction.

PubMed

Rahnemai-Azar, Amir Ata; Sabzevari, Soheil; Irarrázaval, Sebastián; Chao, Tom; Fu, Freddie H

2016-10-01

The anterior cruciate ligament (ACL) is composed of two bundles, which work together to provide both antero-posterior and rotatory stability of the knee. Understanding the anatomy and function of the ACL plays a key role in management of patients with ACL injury. Anatomic ACL reconstruction aims to restore the function of the native ACL. Femoral and tibial tunnels should be placed in their anatomical location accounting for both the native ACL insertion site and bony landmarks. One main component of anatomical individualized ACL reconstruction is customizing the treatment according to each patient's individual characteristics, considering preoperative and intraoperative evaluation of the native ACL and knee bony anatomy. Anatomical individualized reconstruction surgery should also aim to restore the size of the native ACL insertion as well. Using this concept, while single bundle ACL reconstruction can restore the function of the ACL in some patients, double bundle reconstruction is indicated in others to achieve optimal outcome.

A retinal code for motion along the gravitational and body axes

PubMed Central

Sabbah, Shai; Gemmer, John A.; Bhatia-Lin, Ananya; Manoff, Gabrielle; Castro, Gabriel; Siegel, Jesse K.; Jeffery, Nathan; Berson, David M.

2017-01-01

Summary Self-motion triggers complementary visual and vestibular reflexes supporting image-stabilization and balance. Translation through space produces one global pattern of retinal image motion (optic flow), rotation another. We show that each subtype of direction-selective ganglion cell (DSGC) adjusts its direction preference topographically to align with specific translatory optic flow fields, creating a neural ensemble tuned for a specific direction of motion through space. Four cardinal translatory directions are represented, aligned with two axes of high adaptive relevance: the body and gravitational axes. One subtype maximizes its output when the mouse advances, others when it retreats, rises, or falls. ON-DSGCs and ON-OFF-DSGCs share the same spatial geometry but weight the four channels differently. Each subtype ensemble is also tuned for rotation. The relative activation of DSGC channels uniquely encodes every translation and rotation. Though retinal and vestibular systems both encode translatory and rotatory self-motion, their coordinate systems differ. PMID:28607486

The iliotibial band and anterolateral capsule have a combined attachment to the Segond fracture.

PubMed

Albers, Marcio; Shaikh, Humza; Herbst, Elmar; Onishi, Kentaro; Nagai, Kanto; Musahl, Volker; Fu, Freddie H

2018-05-01

The purpose of this report was to describe the injury mechanism, surgical findings, and outcomes in a 21-year-old professional female football player who presented with a complete anterior cruciate ligament (ACL) rupture and Segond fracture. Interview and video analysis were performed to elicit the injury mechanism. Clinical examination and imaging revealed a complete ACL tear, Segond fracture, lateral meniscus tear, MCL sprain, and posterolateral corner sprain. Examination under anaesthesia revealed Grade 2 pivot shift and varus/valgus instability. Surgical examination revealed attachment of the posterior fibres of the iliotibial band and the lateral capsule to the Segond fragment. The fracture was reduced with suture fixation, and an anatomic ACL reconstruction was performed. Follow-up demonstrated rotatory and anterior tibial translation stability, and imaging at 7 months post-operatively revealed no movement and continued osseous integration of the Segond fragment. Level of evidence V.

SOME PROPERTIES OF HYALIN

PubMed Central

Stephens, R. E.; Kane, R. E.

1970-01-01

The principal protein component of the hyaline layer of sea urchin eggs is the calcium-insoluble protein first described by Kane and Hersh. The protein hyalin is abnormally high in acidic amino acids, almost devoid of basic amino acids, and characteristically rich in valine and proline. Essentially all of the cysteine present is found in the disulfide form; no evidence points to intermolecular disulfide linkages. Hyalin from several species has a minimal subunit weight of about 100,000, though evidence exists for a particle three times this weight in urea or guanidine hydrochloride from one species. Optical rotatory dispersion measurements indicate no α-helix content, though the dispersion has unique characteristic features. Addition of small quantities of calcium causes hyalin to gel to a birefringent fibrous form. The fibrous, birefringent form of hyalin is rendered isotropic upon addition of EDTA, but the birefringence is restored with re-addition of divalent cation. PMID:4190067

Effects of physical agitation on yield of greenhouse-grown soybean

NASA Technical Reports Server (NTRS)

Jones, R. S.; Mitchell, C. A.

1992-01-01

Agronomic and horticultural crop species experience reductions in growth and harvestable yield after exposure to physical agitation (also known as mechanical stress), as by wind or rain. A greenhouse study was conducted to test the influence of mechanical stress on soybean yield and to determine if exposure to mechanical stress during discrete growth periods has differential effects on seed yield. A modified rotatory shaker was used to apply seismic (i.e., shaking) stress. Brief, periodic episodes of seismic stress reduced stem length, total seed dry weight, and seed number of soybean [Glycine max (L.) Merr.]. Lodging resistance was greater for plants stressed during vegetative growth or throughout vegetative and reproductive growth than during reproductive growth only. Seed dry weight yield was reduced regardless of the timing or duration of stress application, but was lowest when applied during reproductive development. Seismic stress applied during reproductive growth stages R1 to R2 (Days 3 to 4) was as detrimental to seed dry weight accumulation as was stress applied during growth stages R1 to R6 (Days 39 to 42). Seed dry weight per plant was highly correlated with seed number per plant, and seed number was correlated with the seed number of two- and three-seeded pods. Dry weight per 100 seeds was unaffected by seismic-stress treatment. Growth and yield reductions resulting from treatments applied only during the vegetative stage imply that long-term mechanical effects were induced, from which the plants did not fully recover. It is unclear which yield-controlling physiological processes were affected by mechanical stress. Both transient and long-term effects on yield-controlling processes remain to be elucidated.

[Early Experience with the Vercise^TM DBS System in the Treatment of Dystonic Tremor].

PubMed

Miyagi, Yasushi

2017-03-01

Six cases of dystonic tremor were treated with the Vercise^TM deep brain stimulation(DBS)system, which has the multiple independent current control(MICC)technology. The mean preoperative score of Burke-Fahn-Marsden dystonia rating scale was 16.2±9.4, which was reduced to 6.1±4.6 at 5 months postoperatively. A 65-year-old male presented an intractable dystonic tremor of the jaw, neck, and shoulders due to tardive syndrome. He experienced the successful tremor relief after unipolar DBS in the globus pallidus internus(GPi)with Vercise^TM but complained of dysarthria. Steering the current ventrally induced nausea without alleviating dysarthria, while steering the current dorsally alleviated dysarthria but a further dorsal current induced mandibular dyskinesia. The current steering with MICC enabled the simulation field in GPi with successful balance, maximizing tremor suppression, and minimizing the adverse effects. In a second case, 61-year-old male in whom cervical dystonia with rotatory tremor had been successfully treated with interleaving stimulation of GPi-DBS had needed to repeat the replacement of a non-rechargeable pulse generator in only 15-month interval. After the substitution of Vercise^TM, the interleaving stimulation of 9.5mA in total was replaced by 8.5mA with the current steering of MICC, while the patient's symptomatic control was unchanged. The microlesion effects after lead implantation are unclear and therapeutic effects are often delayed in cases of dystonia;therefore, the submaximal stimulation intensities must be frequently applied in the early phase following the implantation of DBS. A fine current steering of Vercise^TM DBS is very useful in both, the early and late phases of GPi-DBS for dystonic syndrome.

Kinematics of Different Components of the Posterolateral Corner of the Knee in the Lateral Collateral Ligament-intact State: A Human Cadaveric Study.

PubMed

Domnick, Christoph; Frosch, Karl-Heinz; Raschke, Michael J; Vogel, Nils; Schulze, Martin; von Glahn, Mathias; Drenck, Tobias C; Herbort, Mirco

2017-10-01

To determine the static stabilizing effects of different anatomical structures of the posterolateral corner (PLC) of the knee in the lateral collateral ligament (LCL)-intact state. Thirteen fresh-frozen human cadaveric knees were dissected and tested using an industrial robot with an optical tracking system. Kinematics were determined for 134 N anterior/posterior loads, 10 N m valgus/varus loads, and 5 N m internal/external rotatory loads in 0°, 20°, 30°, 60°, and 90° of knee flexion. The PLC structures were dissected and consecutively released: (I) intact knee joint, (II) with released posterior cruciate ligament (PCL), (III) popliteomeniscal fibers, (IV) popliteofibular ligament, (V) arcuat and popliteotibial fibers, (VI) popliteus tendon (PLT), and (VII) LCL. Repeated-measures analysis of variance was performed with significance set at P < .05. After releasing the PCL, posterior tibial translation increased by 5.2 mm at 20° to 9.4 mm at 90° of joint flexion (P < .0001). A mild 1.8° varus instability was measured in 0° of flexion (P = .0017). After releasing the PLC structures, posterior tibial translation further increased by 2.9 mm at 20° to 5.9 mm at 90° of flexion (P < .05) and external rotation angle increased by 2.6° at 0° to 7.9° at 90° of flexion (P < .05, vs II). Varus stability did not decrease. Mild differences between states V and VI were found in 60° and 90° external rotation tests (2.1° and 3.1°; P < .05). The connecting ligaments/fibers to the PLT act as a primary static stabilizer against external rotatory loads and a secondary stabilizer against posterior tibial loads (when PCL is injured). After releasing these structures, most static stabilizing function of the intact PLT is lost. The PLC has no varus-stabilizing function in the LCL-intact knee. Anatomy and function of these structures for primary and secondary joint stability should be considered for clinical diagnostics and when performing surgery in the PLC. Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

In vitro effects of virgin microplastics on fish head-kidney leucocyte activities.

PubMed

Espinosa, Cristóbal; García Beltrán, José María; Esteban, María Angeles; Cuesta, Alberto

2018-04-01

Microplastics are well-documented pollutants in the marine environment that result from production or fragmentation of larger plastic items. The knowledge about the direct effects of microplastics on immunity, including fish, is still very limited. We investigated the in vitro effects of microplastics [polyvinylchloride (PVC) and polyethylene (PE)] on gilthead seabream (Sparus aurata) and European sea bass (Dicentrarchus labrax) head-kidney leucocytes (HKLs). After 1 and 24 h of exposure of HKLs with 0 (control), 1, 10 and 100 mg mL -1 MPs in a rotatory system, cell viability, innate immune parameters (phagocytic, respiratory burst and peroxidase activities) and the expression of genes related to inflammation (il1b), oxidative stress (nrf2, prdx3), metabolism of xenobiotics (cyp1a1, mta) and cell apoptosis (casp3) were studied. Microplastics failed to affect the cell viability of HKLs. In addition, they provoke very few significant effects on the main cellular innate immune activities, as decrease on phagocytosis or increase in the respiratory burst of HKLs with the highest dose of microplastics tested. Furthermore, microplastics failed to affect the expression of the selected genes on sea bass or seabream, except the nrf2 which was up-regulated in seabream HKLs incubated with the highest doses. Present results seem to suggest that continue exposure of fish to PVC or PE microplastics could impair fish immune parameters probably due to the oxidative stress produced in the fish leucocytes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hydrodynamic properties of human cervical-mucus glycoproteins in 6M-guanidinium chloride.

PubMed Central

Sheehan, J K; Carlstedt, I

1984-01-01

Cervical mucins and fragments thereof were studied by sedimentation-velocity, rotatory viscometry and laser light-scattering performed as photon-correlation spectroscopy as well as low-angle total-intensity measurements. The Mr of the whole mucins is 10 X 10(6)-15 X 10(6), whereas fragments obtained after reduction of disulphide bonds ('subunits') have Mr 2.1 X 10(6)-2.9 X 10(6), depending on the method used. Subsequent trypsin digestion of subunits afforded glycopeptides with Mr approx. 0.4 X 10(6). The high frictional ratio for the whole mucins is interpreted as a large degree of expansion. The Stokes radius calculated from the diffusion coefficient is approx. 110nm for the whole mucins, which is in agreement with that estimated from the radius of gyration (130nm) by using the concept of the equivalent hydrodynamic sphere. The ratio of the concentration-dependence parameter for the reciprocal sedimentation coefficient (Ks) to the intrinsic viscosity ( [eta] ) for the whole mucins is 1.42, suggesting that the individual macromolecule occupies a spheroidal domain in solution. The relationship between [eta] and Mr for whole mucins, subunits and T-domains suggests that they are linear flexible macromolecules behaving as somewhat 'stiff' random coils. This conclusion is supported by the relationships between the sedimentation coefficients, the diffusion coefficients and the Mr. The hydrodynamic behaviour of the mucins is thus close to that expected for coiling macromolecules entrapping a lot of solvent, which is consistent with the postulated polymeric structure. PMID:6696734

Microleakage in Class V cavities with self-etching adhesive system and conventional rotatory or laser Er,Cr:YSGG

PubMed Central

Arnabat, J; España-Tost, T

2012-01-01

Objective: To analyse microleakage in Class V cavity preparation with Er;Cr:YSGG at different parameters using a self-etching adhesive system. Background: Several studies reported microleakage around composite restorations when cavity preparation is done or treated by Er;Cr:YSGG laser. We want to compare different energy densities in order to obtain the best parameters, when using a self-etching adhesive system. Methods: A class V preparations was performed in 120 samples of human teeth were divided in 3 groups: (1) Preparation using the burr. (2) Er;Cr:YSGG laser preparation with high energy 4W, 30 Hz, 50% Water 50% Air and (3) Er;Cr:YSGG laser preparation lower energy 1.5 W, 30 Hz, 30% Water 30% Air. All the samples were restored with self-etching adhesive system and hybrid composite. Thermocycling (5000 cycles) and immersed in 0.5% fuchsin. The restorations were sectioned and evaluated the microleakage with a stereomicroscope. Results: Lower energy laser used for preparation showed significant differences in enamel and dentin. To group 3, the microleakage in the enamel was less, whilst the group 1, treated with the turbine, showed less microleakage at dentin level. Group 2 showed the highest microleakage at dentin/cement level. Conclusion: Burr preparation gives the lowest microleakage at cement/dentin level, whilst Er;Cr:YSGG laser at lower power has the low energy obtains lowest microleakage at enamel. On the contrary high-energy settings produce inferior results in terms of microleakage. PMID:24511195

Effects of static orientation upon human optokinetic afternystagmus

NASA Technical Reports Server (NTRS)

Wall, C. 3rd; Merfeld, D. M.; Zupan, L.

1999-01-01

"Normal" human subjects were placed in a series of 5 static orientations with respect to gravity and were asked to view an optokinetic display moving at a constant angular velocity. The axis of rotation coincided with the subject's rostro-caudal axis and produced horizontal optokinetic nystagmus and afternystagmus. Wall (1) previously reported that these optokinetic afternystagmus responses were not well characterized by parametric fits to slow component velocity. The response for nose-up, however, was larger than for nose-down. This suggested that the horizontal eye movements measured during optokinetic stimulation might include an induced linear VOR component as presented in the body of this paper. To investigate this hypothesis, another analysis of these data has been made using cumulative slow component eye position. Some subjects' responses had reversals in afternystagmus direction. These reversals were "filled in" by a zero slow component velocity. This method of analysis gives a much more consistent result across subjects and shows that, on average, responses from the nose-down horizontal (prone) orientation are greatly reduced (p < 0.05) compared to other horizontal and vertical orientations. Average responses are compared to responses predicted by a model previously used to predict successfully the responses to post-rotatory nystagmus after earth horizontal axis rotation. Ten of 11 subjects had larger responses in their supine than their prone orientation. Application of horizontal axis optokinetic afternystagmus for clinical otolith function testing, and implications for altered gravity experiments are discussed.

[A gearing mechanism with 4 degrees of freedom for robotic applications in medicine].

PubMed

Pott, P; Weiser, P; Scharf, H P; Schwarz, M

2004-06-01

Applications in robot-aided surgery are currently based on modifications of manipulators used in industrial manufacturing processes. In this paper we describe novel rotatory kinematics for a manipulator, specially developed for deployment in robot-aided surgery. The construction of the gearing mechanism used for the positioning and orientation of a linkage point is described. Forward and inverse kinematics were calculated, and a constructive solution proposed. The gearing mechanism is based on two disk systems, each of which consists of two opposing rotatable discs. The construction was designed in such a way that the linkage point can be positioned freely anywhere within the mechanism's range of motion. The kinematics thus permits an x-y-positioning via rotating movements only. The spatial arrangement of two of such disc systems permits movements in four degrees of freedom (DOF). The construction is compact, but can be further miniaturized, is flexible and manufacturing costs are low. On the basis of this mechanical concept a new, small automated manipulator for surgical application will be developed.

'Cardiogenic vertigo'--true vertigo as the presenting manifestation of primary cardiac disease.

PubMed

Newman-Toker, David E; Camargo, Carlos A

2006-03-01

A 90-year-old woman presented to a hospital emergency department with a brief loss of consciousness that was heralded by spinning vertigo lasting approximately 2 min. She had a long history of intermittent brief episodes of rotatory vertigo, presyncope, and non-vertiginous dizziness, occurring either with or without loss of consciousness. Although initially attributed to symptomatic carotid artery stenosis, these episodes persisted, despite surgical restoration of carotid artery blood flow 1 year after her first syncope. Her medical history was otherwise notable for hypertension, mild depression and a gradual decline in gait and balance function attributed to left hip arthritis and older age. Bedside history and examination, non-contrast head CT scan, electrocardiogram, transthoracic echocardiogram, and bedside cardiac telemetry. Sick sinus syndrome or severe reflex bradycardia with asystole causing recurrent, episodic vertigo, presyncope, non-vertiginous dizziness and syncope (Stokes-Adams attacks). Placement of a temporary pacing wire, followed by surgical implantation of a single-chamber ventricular (VVI) pacemaker.

Lateral epicondylitis and beyond: imaging of lateral elbow pain with clinical-radiologic correlation.

PubMed

Kotnis, Nikhil A; Chiavaras, Mary M; Harish, Srinivasan

2012-04-01

The diagnosis of lateral epicondylitis is often straightforward and can be made on the basis of clinical findings. However, radiological assessment is valuable where the clinical picture is less clear or where symptoms are refractory to treatment. Demographics, aspects of clinical history, or certain physical signs may suggest an alternate diagnosis. Knowledge of the typical clinical presentation and imaging findings of lateral epicondylitis, in addition to other potential causes of lateral elbow pain, is necessary. These include entrapment of the posterior interosseous and lateral antebrachial cutaneous nerves, posterolateral rotatory instability, posterolateral plica syndrome, Panner's disease, osteochondritis dissecans of the capitellum, radiocapitellar overload syndrome, occult fractures and chondral-osseous impaction injuries, and radiocapitellar arthritis. Knowledge of these potential masquerades of lateral epicondylitis and their characteristic clinical and imaging features is essential for accurate diagnosis. The goal of this review is to provide an approach to the imaging of lateral elbow pain, discussing the relevant anatomy, various causes, and discriminating factors, which will allow for an accurate diagnosis.

A hybrid feature selection and health indicator construction scheme for delay-time-based degradation modelling of rolling element bearings

NASA Astrophysics Data System (ADS)

Zhang, Bin; Deng, Congying; Zhang, Yi

2018-03-01

Rolling element bearings are mechanical components used frequently in most rotating machinery and they are also vulnerable links representing the main source of failures in such systems. Thus, health condition monitoring and fault diagnosis of rolling element bearings have long been studied to improve operational reliability and maintenance efficiency of rotatory machines. Over the past decade, prognosis that enables forewarning of failure and estimation of residual life attracted increasing attention. To accurately and efficiently predict failure of the rolling element bearing, the degradation requires to be well represented and modelled. For this purpose, degradation of the rolling element bearing is analysed with the delay-time-based model in this paper. Also, a hybrid feature selection and health indicator construction scheme is proposed for extraction of the bearing health relevant information from condition monitoring sensor data. Effectiveness of the presented approach is validated through case studies on rolling element bearing run-to-failure experiments.

Synthesis of the natural product building block 5-(3-bromophenyl)-4-hydroxy-5-methylhexan-2-one and its chiral characterization by using chiroptical spectroscopy.

PubMed

De Gussem, Ewoud; Cornelus, Jelle; Pieters, Sam; Van den Bossche, Dries; Van der Eycken, Johan; Herrebout, Wouter; Bultinck, Patrick

2013-10-07

The absolute configuration of 5-(3-bromophenyl)-4-hydroxy-5-methylhexan-2-one, an intermediate in the synthesis of various natural products, is assigned by using vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and optical rotatory dispersion (ORD). Experimental spectra were compared to density functional theory (DFT) calculations of the molecule with known configuration. These three techniques independently confirm that the absolute configuration is (S)-5-(3-bromophenyl)-4-hydroxy-5-methylhexan-2-one, thus enabling us to assign the absolute configuration with high reliability. The reliability of the VCD analysis was assessed quantitatively by using the CompareVOA program. We found that, in cases in which the agreement between theory and experiment was very good, a value of 10 cm(-1) for the triangular weighting function gave a more-realistic discriminative power between enantiomers than the default value of 20 cm(-1). Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

Three dimensional eye movements of squirrel monkeys following postrotatory tilt

NASA Technical Reports Server (NTRS)

Merfeld, D. M.; Young, L. R.; Paige, G. D.; Tomko, D. L.

1993-01-01

Three-dimensional squirrel monkey eye movements were recorded during and immediately following rotation around an earth-vertical yaw axis (160 degrees/s steady state, 100 degrees/s2 acceleration and deceleration). To study interactions between the horizontal angular vestibulo-ocular reflex (VOR) and head orientation, postrotatory VOR alignment was changed relative to gravity by tilting the head out of the horizontal plane (pitch or roll tilt between 15 degrees and 90 degrees) immediately after cessation of motion. Results showed that in addition to post rotatory horizontal nystagmus, vertical nystagmus followed tilts to the left or right (roll), and torsional nystagmus followed forward or backward (pitch) tilts. When the time course and spatial orientation of eye velocity were considered in three dimensions, the axis of eye rotation always shifted toward alignment with gravity, and the postrotatory horizontal VOR decay was accelerated by the tilts. These phenomena may reflect a neural process that resolves the sensory conflict induced by this postrotatory tilt paradigm.

Experiments on the origin of molecular chirality by parity non-conservation during beta-decay

NASA Technical Reports Server (NTRS)

Bonner, W. A.

1973-01-01

Experiments are described to test a theory for the origin of optical activity wherein the longitudinally polarized electrons resulting from parity violation during radioactive beta decay, and their resulting circularly polarized Bremsstrahlung, might interact asymmetrically with organic matter to yield optically active products. Experiments involve subjecting a number of racemic and optically active amino acid samples to irradiation in a 61700 Ci90SR-90Y beta radiation source for a period of 1.34 years, then examining them for any asymmetric effects by means of optical rotatory dispersion and analytical gas chromatography. In the cases of D,L-leucine, norleucine, norvaline and proline as solids, of D,L-leucine in solution and of D,L-tyrosine in alkaline solution no optical rotation was observed during CRD measurements in the 250-630 nm spectral region. While slight differences were noted in the percent radiolysis of solid D- (12.7%) and L-leucine (16.2%) as determined by GC, no enrichment of either enantiomer was found.

Development of near infrared spectrometer for gem materials study

NASA Astrophysics Data System (ADS)

Jindata, W.; Meesiri, W.; Wongkokua, W.

2015-07-01

Most of gem materials can be characterized by infrared absorption spectroscopy. Normally, mid infrared absorption technique has been applied for investigating fundamental vibrational modes. However, for some gem materials, such as tourmaline, NIR is a better choice due to differentiation. Most commercial NIR spectrometers employ complicated dispersive grating or Fourier transform techniques. In this work, we developed a filter type NIR spectrometer with the availability of high efficiency and low-cost narrow bandpass NIR interference filters to be taught in a physics laboratory. The instrument was designed for transmission-mode configuration. A 50W halogen lamp was used as NIR source. There were fourteen NIR filters mounted on a rotatory wheel for wavelength selection ranging from 1000-1650 nm with steps of 50 nm. A 1.0 mm diameter of InGaAs photodiode was used as the detector for the spectrometer. Hence, transparent gem materials can be used as samples for experiment. Student can learn vibrational absorption spectroscopy as well as Beer-Lambert law from the development of this instrument.

Computational modeling of the nonlinear stochastic dynamics of horizontal drillstrings

NASA Astrophysics Data System (ADS)

Cunha, Americo; Soize, Christian; Sampaio, Rubens

2015-11-01

This work intends to analyze the nonlinear stochastic dynamics of drillstrings in horizontal configuration. For this purpose, it considers a beam theory, with effects of rotatory inertia and shear deformation, which is capable of reproducing the large displacements that the beam undergoes. The friction and shock effects, due to beam/borehole wall transversal impacts, as well as the force and torque induced by bit-rock interaction, are also considered in the model. Uncertainties of bit-rock interaction model are taken into account using a parametric probabilistic approach. Numerical simulations have shown that the mechanical system of interest has a very rich nonlinear stochastic dynamics, which generate phenomena such as bit-bounce, stick-slip, and transverse impacts. A study aiming to maximize the drilling process efficiency, varying drillstring velocities of translation and rotation is presented. Also, the work presents the definition and solution of two optimizations problems, one deterministic and one robust, where the objective is to maximize drillstring rate of penetration into the soil respecting its structural limits.

Revision allograft reconstruction of the lateral collateral ligament complex in elbows with previous failed reconstruction and persistent posterolateral rotatory instability.

PubMed

Baghdadi, Yaser M K; Morrey, Bernard F; O'Driscoll, Shawn W; Steinmann, Scott P; Sanchez-Sotelo, Joaquin

2014-07-01

Primary reconstruction of the lateral collateral ligament complex (LCLC) using graft tissue restores elbow stability in many, but not all, elbows with acute or chronic posterolateral rotatory instability (PLRI). Revision reconstruction using a tendon allograft is occasionally considered for persistent PLRI, but the outcome of revision ligament reconstruction in this setting is largely unknown. We determined whether revision allograft ligament reconstruction can (1) restore the stability and (2) result in improved elbow scores for patients with persistent PLRI of the elbow after a previous failed primary reconstructive attempt and in the context of the diverse pathology being addressed. Between 2001 and 2011, 160 surgical elbow procedures were performed at our institution for the LCLC reconstruction using allograft tissue. Only patients undergoing revision allograft reconstruction of the LCLC for persistent PLRI with a previous failed primary reconstructive attempt using graft tissue and at least I year of followup were included in the study. Eleven patients (11 elbows) fulfilled our inclusion criteria and formed our study cohort. The cohort consisted of six female patients and five male patients. The mean age at the time of revision surgery was 36 years (range, 14-59 years). The revision allograft reconstruction was carried out after a mean of 3 years (range, 2.5 months to 9 years) from a failed attempted reconstruction of the LCLC. Osseous deficiency to some extent was identified in the preoperative radiographs of eight elbows. Mean followup was 5 years (range, 1-12 years). Revision allograft reconstruction of the LCLC restored elbow stability in eight of the 11 elbows; two of the three elbows with persistent instability were operated on a third time (at 6 and 7 months after allograft revision reconstruction). For elbows with no persistent instability, the mean Mayo Elbow Performance Score at most recent followup was 83 points (range, 60-100 points), and six elbows were rated with a good or excellent result. All patients with persistent instability had some degree of preoperative bone loss. Revision allograft reconstruction of the LCLC is an option for treating recurrent PLRI, although this is a complex and resistant problem, and nearly ½ of the patients in this cohort either had persistent instability and/or had a fair or poor elbow score. Level IV, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.

Long-term evaluation of the effect of middle ear effusion on the vestibular system in children.

PubMed

Pazdro-Zastawny, Katarzyna; Pośpiech, Lucyna; Zatoński, Tomasz

2018-06-01

Otitis media with effusion (OME) is one of the most common clinical conditions in childhood. Fluid accumulation in the middle ear may impact inner ear. The purpose of this random sample cohort study was to investigate whether the past history of middle ear effusion has a long-term negative impact on the vestibular system in children. The study was carried out on 22 children aged 7-15 years who had undergone drainage of the middle ear 5 years before evaluation. The control group consisted of 29 healthy children aged 4-17 years. Vestibular function was examined using sway posturography and electronystagmography (ENG). The stabilogram parameters of the study group and the control group were compared. The field of developed area (FDA) and the average body sway velocity (ASV) were analyzed. Elevated stabilogram parameters of FDA and ASV, both with eyes open and eyes closed, were found in the study group. Statistically significant values (p < 0.05) were present for ASV with eyes open and with eyes closed. The ENG recordings were analyzed in both groups. In the study group, spontaneous nystagmus was observed in 40.9% of the children and positional nystagmus occurred in 63.6% of the children. According to tests, eye tracking test was impaired in 27.3% of cases. Rotatory chair testing revealed asymmetry in 18.2% of the children. The presence of effusion in the middle ear in the past has a negative impact on the vestibular part of the inner ear. Clinicians should be aware of the possible negative impact of middle ear effusion on the vestibular function in children with a history of otitis media with effusion. With seeimingly asymptomatic children clinicians should inquire parents about symptoms of dysequlibrium and imbalance. Copyright © 2018 Elsevier B.V. All rights reserved.

Absolute configurations of phytotoxins seiricardine A and inuloxin A obtained by chiroptical studies.

PubMed

Santoro, Ernesto; Mazzeo, Giuseppe; Petrovic, Ana G; Cimmino, Alessio; Koshoubu, Jun; Evidente, Antonio; Berova, Nina; Superchi, Stefano

2015-08-01

The absolute configuration (AC) of the plant phytotoxin inuloxin A, produced by Inula viscosa, and of the fungal phytotoxin seiricardine A, obtained from Seiridium fungi, pathogen for cypress, has been determined by experimental measurements and theoretical simulations of chiroptical properties of three related methods, namely, Optical Rotatory Dispersion (ORD), Electronic Circular Dichroism (ECD), and Vibrational Circular Dichroism (VCD). Computational prediction by Density Functional Theory (DFT) of VCD spectra and by Time-dependent DFT (TDDFT) of ORD and ECD spectra allowed to assign (7R,8R,10S) AC to naturally occurring (+)-inuloxin A. In the case of compound (-)-seiricardine A, which lacks useful for the analysis UV-Vis absorption, and thus provides a hardly detectable ECD spectrum and quite low ORD values, an introduction of a suitable chromophore by chemical derivatization was performed. The corresponding derivative, 2-O-p-bromobenzoate ester, gave rise to an intense ECD spectrum and higher ORD and VCD values. The comparison of computed spectra with the experimental ones allowed to assign (1S,2R,3aS,4S,5R,7aS) AC to (-)-2-O-p-bromobenzoate ester of seiricardine A and then to (-)-seiricardine A. This study further supports a recent trend of concerted application of more than a single chiroptical technique toward an unambiguous assignment of AC of flexible and complex natural products. Moreover, the use of chemical derivatization, with insertion of suitable chromophoric moieties has allowed to treat also UV-Vis transparent molecules by ECD and ORD spectroscopies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Lumbar scoliosis associated with spinal stenosis in idiopathic and degenerative cases.

PubMed

Le Huec, J C; Cogniet, A; Mazas, S; Faundez, A

2016-10-01

Degenerative de novo scoliosis is commonly present in older adult patients. The degenerative process including disc bulging, facet arthritis, and ligamentum flavum hypertrophy contributes to the appearance of symptoms of spinal stenosis. Idiopathic scoliosis has also degenerative changes that can lead to spinal stenosis. The aetiology, prevalence, biomechanics, classification, symptomatology, and treatment of idiopathic and degenerative lumbar scoliosis in association with spinal stenosis are reviewed. Review study is based on a review of pertinent but non-exhaustive literature of the last 20 years in PubMed in English language. Retrospective analysis of studies focused on all parameters concerning scoliosis associated with stenosis. Very few publications have focused specifically on idiopathic scoliosis and stenosis, and this was before the advent of modern segmental instrumentation. On the other hand, many papers were found for degenerative scoliosis and stenosis with treatment methods based on aetiology of spinal canal stenosis and analysis of global sagittal and frontal parameters. Satisfactory clinical results after operative treatment range from 83 to 96 % but with increased percentage of complications. Recent literature analysed the importance of stabilizing or not the spine after decompression in such situation knowing the increasing risk of instability after facet resection. No prospective randomized studies were found to support short instrumentation. Long instrumentation and fusion to prevent distabilization after decompression were always associated with higher complication rates. Imbalance patients with unsatisfactory compensation capacities were at risk of complications. Operative treatment using newly proposed classification system of lumbar scoliosis with associated canal stenosis is useful. Sagittal balance and rotatory dislocation are the main parameters to analyse to determine the length of fusion.

Mechanotransduction Mechanisms for Intraventricular Diastolic Vortex Forces and Myocardial Deformations: Part 1

PubMed Central

Pasipoularides, Ares

2015-01-01

Epigenetic mechanisms are fundamental in cardiac adaptations, remodeling, reverse remodeling, and disease. This 2-article series proposes that variable forces associated with diastolic RV/LV rotatory intraventricular flows can exert physiologically and clinically important, albeit still unappreciated, epigenetic actions influencing functional and morphological cardiac adaptations and/or maladaptations. Taken in-toto, the 2-part survey formulates a new paradigm in which intraventricular diastolic filling vortex-associated forces play a fundamental epigenetic role, and examines how heart cells react to these forces. The objective is to provide a perspective on vortical epigenetic effects, to introduce emerging ideas and suggest directions of multidisciplinary translational research. The main goal is to make pertinent biophysics and cytomechanical dynamic systems concepts accessible to interested translational and clinical cardiologists. I recognize that the diversity of the epigenetic problems can give rise to a diversity of approaches and multifaceted specialized research undertakings. Specificity may dominate the picture. However, I take a contrasting approach. Are there concepts that are central enough that they should be developed in some detail? Broadness competes with specificity. Would however this viewpoint allow for a more encompassing view that may otherwise be lost by generation of fragmented results? Part 1 serves as a general introduction, focusing on background concepts, on intracardiac vortex imaging methods, and on diastolic filling vortex-associated forces acting epigenetically on RV/LV endocardium and myocardium. Part 2 will describe pertinent available pluridisciplinary knowledge/research relating to mechanotransduction mechanisms for intraventricular diastolic vortex forces and myocardial deformations and to their epigenetic actions on myocardial and ventricular function and adaptations. PMID:25624114

Release of antibiotic resistant bacteria and genes in the effluent and biosolids of five wastewater utilities in Michigan.

PubMed

Munir, Mariya; Wong, Kelvin; Xagoraraki, Irene

2011-01-01

The purpose of this study was to quantify the occurrence and release of antibiotic resistant genes (ARGs) and antibiotic resistant bacteria (ARB) into the environment through the effluent and biosolids of different wastewater treatment utilities including an MBR (Membrane Biological Reactor) utility, conventional utilities (Activated Sludge, Oxidative Ditch and Rotatory Biological Contactors-RBCs) and multiple sludge treatment processes (Dewatering, Gravity Thickening, Anaerobic Digestion and Lime Stabilization). Samples of raw wastewater, pre- and post-disinfected effluents, and biosolids were monitored for tetracycline resistant genes (tetW and tetO) and sulfonamide resistant gene (Sul-I) and tetracycline and sulfonamide resistant bacteria. ARGs and ARB concentrations in the final effluent were found to be in the range of ND(non-detectable)-2.33 × 10(6) copies/100 mL and 5.00 × 10(2)-6.10 × 10(5) CFU/100 mL respectively. Concentrations of ARGs (tetW and tetO) and 16s rRNA gene in the MBR effluent were observed to be 1-3 log less, compared to conventional treatment utilities. Significantly higher removals of ARGs and ARB were observed in the MBR facility (range of removal: 2.57-7.06 logs) compared to that in conventional treatment plants (range of removal: 2.37-4.56 logs) (p < 0.05). Disinfection (Chlorination and UV) processes did not contribute in significant reduction of ARGs and ARB (p > 0.05). In biosolids, ARGs and ARB concentrations were found to be in the range of 5.61 × 10(6)-4.32 × 10(9) copies/g and 3.17 × 10(4)-1.85 × 10(9) CFU/g, respectively. Significant differences (p < 0.05) were observed in concentrations of ARGs (except tetW) and ARB between the advanced biosolid treatment methods (i.e., anaerobic digestion and lime stabilization) and the conventional dewatering and gravity thickening methods. Copyright © 2010 Elsevier Ltd. All rights reserved.

Observations of the interaction between near-inertial waves and mesoscale eddies

NASA Astrophysics Data System (ADS)

Martínez-Marrero, Antonio; Sangrá, Pablo; Caldeira, Rui; Aguiar-González, Borja; Rodríguez-Santana, Ángel

2014-05-01

Trajectories of eight drifters dragged below the surface mixed layer and current meter data from a mooring are used to analyse the interaction between near-inertial waves and mesoscale eddies. Drifters were deployed within eddies generated downstream of Canary and Madeira islands between 1998 and 2007. The mooring was installed in the passage of cyclonic eddies induced by Gran Canaria island during 2006. Rotatory wavelet analysis of Lagrangian velocities shows a clear relationship between the near-inertial waves' intrinsic frequencies and the eddy angular velocities. The results reveal that near-inertial waves reach a minimum frequency of half the planetary vorticity (f/2) in the inner core of young anticyclonic eddies rotating with its maximum absolute angular speed of f/2. The highest amplitudes of the observed inertial motions are also found within anticyclonic eddies evidencing the trapping of inertial waves. Finally, the analysis of the current meter series show frequency fluctuations of the near-inertial currents in the upper 500 meters that are related to the passage of cyclonic eddies. These fluctuations appear to be consistent with the variation of the background vorticity produced by the eddies.

Racemic amino acids from the ultraviolet photolysis of interstellar ice analogues.

PubMed

Bernstein, Max P; Dworkin, Jason P; Sandford, Scott A; Cooper, George W; Allamandola, Louis J

2002-03-28

The delivery of extraterrestrial organic molecules to Earth by meteorites may have been important for the origin and early evolution of life. Indigenous amino acids have been found in meteorites-over 70 in the Murchison meteorite alone. Although it has been generally accepted that the meteoritic amino acids formed in liquid water on a parent body, the water in the Murchison meteorite is depleted in deuterium relative to the indigenous organic acids. Moreover, the meteoritical evidence for an excess of laevo-rotatory amino acids is hard to understand in the context of liquid-water reactions on meteorite parent bodies. Here we report a laboratory demonstration that glycine, alanine and serine naturally form from ultraviolet photolysis of the analogues of icy interstellar grains. Such amino acids would naturally have a deuterium excess similar to that seen in interstellar molecular clouds, and the formation process could also result in enantiomeric excesses if the incident radiation is circularly polarized. These results suggest that at least some meteoritic amino acids are the result of interstellar photochemistry, rather than formation in liquid water on an early Solar System body.

Dizziness: relating the severity of vertigo to the degree of handicap by measuring vestibular impairment.

PubMed

Pérez, Nicolás; Martin, Eduardo; Garcia-Tapia, Rafael

2003-03-01

We sought to correlate the severity of vertigo and handicap in patients with vestibular pathology according to measures of impairment. We conducted a prospective assessment of patients with dizziness by means of caloric, rotatory test, and computerized dynamic posturography to estimate impairment. Handicap and severity of vertigo were determined with specific questionnaires (Dizziness Handicap Inventory and UCLA-DQ). A fair relationship were found between severity of dizziness and vestibular handicap. When impairment was taken into consideration, values were still fair and only moderate for a group of patients with an abnormal caloric test as the only pathologic finding. The composite score from the sensory organization test portion of the computerized dynamic posturography is fairly correlated to severity of vertigo and handicap in the whole population of patients, but no correlation was found when they were assigned to groups of vestibular impairment. To assess vestibular impairment, the results from several tests must be taken into account. However, vestibular handicap is not solely explained with measurements of impairment and/or severity.

Hydrothermal synthesis, crystal structures, and enantioselective adsorption property of bis(L-histidinato)nickel(II) monohydrate

NASA Astrophysics Data System (ADS)

Ramos, Christian Paul L.; Conato, Marlon T.

2018-05-01

Despite the numerous researches in metal-organic frameworks (MOFs), there are only few reports on biologically important amino acids, histidine in particular, on its use as bridging ligand in the construction of open-framework architectures. In this work, hydrothermal synthesis was used to prepare a compound based on Ni2+ and histidine. The coordination assembly of imidazole side chain of histidine with divalent nickel ions in aqueous condition yielded purple prismatic solids. Single crystal X-ray diffraction (XRD) analysis of the product revealed structure for Ni(C6H8N3O2)2 • H2O that has a monoclinic (C2) structure with lattice parameters, a = 29.41, b = 8.27, c = 6.31 Å, β = 90.01 ˚. Circular dichroism - optical rotatory dispersion (CD-ORD), Powder X-ray diffraction (PXRD) and Fourier transform - infrared spectroscopy (FT-IR) analyses are conducted to further characterize the crystals. Enantioselective adsorption analysis using racemic mixture of 2-butanol confirmed bis(L-histidinato)nickel(II) monohydrate MOF crystal's enantioselective property preferentially favoring the adsorption of (S)-2-butanol isomer.

Plate mode velocities in graphite/epoxy plates

NASA Technical Reports Server (NTRS)

Prosser, W. H.; Gorman, M. R.

1994-01-01

Measurements of the velocities of the extensional and flexural plate modes were made along three directions of propagation in four graphite/epoxy composite plates. The acoustic signals were generated by simulated acoustic emission events (pencil lead breaks or Hsu-Neilson sources) and detected by by broadband ultrasonic transducers. The first arrival of the extensional plate mode, which is nondispersive at low frequencies, was measured at a number of different distances from the source along the propagation direction of interest. The velocity was determined by plotting the distance versus arrival time and computing its slope. Because of the large dispersion of the flexural mode, a Fourier phase velocity technique was used to characterize this mode. The velocity was measured up to a frequency of 160 kHz. Theoretical predictions of the velocities of these modes were also made and compared with experimental observations. Classical plate theory yields good agreement with the measured extensional velocities. For predictions of the dispersion of the flexural mode, Mindlin plates theory, which includes the effects of shear deformation and rotatory inertia was shown to give better agreement with the experimental measurements.

The Effect of the π-Electron Delocalization Curvature on the Two-Photon Circular Dichroism of Molecules with Axial Chirality.

PubMed

Diaz, Carlos; Lin, Na; Toro, Carlos; Passier, Remy; Rizzo, Antonio; Hernández, Florencio E

2012-07-05

Herein we report on the theoretical-experimental study of the effect of curvature of the π-electron delocalization on the two-photon circular dichroism (TPCD) of a family of optically active biaryl derivatives (S-BINOL, S-VANOL, and S-VAPOL). The comparative analysis of the influence of the different transition moments to their corresponding TPCD rotatory strength reveals an enhanced contribution of the magnetic transition dipole moment on VAPOL. This effect is hereby attributed to the additional twist in the π-electron delocalization on this compound. TPCD measurements were done using the double L-scan technique in the picosecond regime. Theoretical calculations were completed using modern analytical response theory, within a time-dependent density functional theory (TD-DFT) approach, at both, B3LYP and CAM-B3LYP levels, with the aug-cc-pVDZ basis set for S-BINOL and S-VANOL, and 6-31G* for S-VAPOL. Solvent effects were included by means of the polarizable continuum model (PCM) in CH2Cl2.

Issues related to dust aerosols in the magnesite industry. I. Chamber exposure.

PubMed

Reichrtová, E; Takác, L

1992-01-01

The present paper is an overview of the experimental research into the effects of flue magnesite dust in the magnesite industry in which the raw material (magnesite) is processed into refractory magnesite clinker. The issues related to dust are divided into two problem areas: a) dust aerosol arising in the process of ore mining and consisting largely of magnesite (MgCO3) and b) dust aerosol originating during ore baking in rotatory furnaces and made up mostly of MgO. Thus, larger groups of people become exposed to these aerosols as a result of solid particles escaping into the atmosphere than in the case of occupational exposure. Experimental research carried out on laboratory animals after chamber exposure provided findings on the deposition, retention and elimination of magnesite dust, on impaired balance between magnesium and calcium leading to damage of biological membranes, on how the immune profile or reproduction and embryogenesis is impacted as well as on the possible interaction with sodium salicylate as a result of an impaired acid base balance. These findings are followed up by evidence produced in the course of biological monitoring (Part II).

Some new thoughts about long-term precession formula

NASA Astrophysics Data System (ADS)

Vondrák, J.; Capitaine, N.; Wallace, P.

2011-10-01

In our preceding study (Vondrák et al. 2009) we formulated developments for the precessional contribution to the CIP X, Y coordinates suitable for use over long time intervals. They were fitted to IAU 2006 close to J2000.0 and to the numerical integration of the ecliptic (using the integrator package Mercury 6) and of the general precession and obliquity (using Laskar's solution LA93) for more distant epochs. Now we define the boundary between precession and nutation (both are periodic) to avoid their overlap. We use the IAU 2006 model (that is based on the Bretagnon's solution VSOP87 and the JPL planetary ephemerides DE406) to represent the precession of the ecliptic close to J2000.0, a new integration using Mercury 6 for more distant epochs, and Laskar's LA93 solution to represent general precession and obliquity. The goal is to obtain new developments for different sets of precession angles that would fit to modern observations near J2000.0, and at the same time to numerical integration of the translatory-rotatory motions of solar system bodies on scales of several thousand centuries.

Racemic amino acids from the ultraviolet photolysis of interstellar ice analogues

NASA Technical Reports Server (NTRS)

Bernstein, Max P.; Dworkin, Jason P.; Sandford, Scott A.; Cooper, George W.; Allamandola, Louis J.

2002-01-01

The delivery of extraterrestrial organic molecules to Earth by meteorites may have been important for the origin and early evolution of life. Indigenous amino acids have been found in meteorites-over 70 in the Murchison meteorite alone. Although it has been generally accepted that the meteoritic amino acids formed in liquid water on a parent body, the water in the Murchison meteorite is depleted in deuterium relative to the indigenous organic acids. Moreover, the meteoritical evidence for an excess of laevo-rotatory amino acids is hard to understand in the context of liquid-water reactions on meteorite parent bodies. Here we report a laboratory demonstration that glycine, alanine and serine naturally form from ultraviolet photolysis of the analogues of icy interstellar grains. Such amino acids would naturally have a deuterium excess similar to that seen in interstellar molecular clouds, and the formation process could also result in enantiomeric excesses if the incident radiation is circularly polarized. These results suggest that at least some meteoritic amino acids are the result of interstellar photochemistry, rather than formation in liquid water on an early Solar System body.

Migration of titanium cable into spinal cord and spontaneous C2 and C3 fusion: Case report of possible causes of fatigue failure after posterior atlantoaxial fixation.

PubMed

Li, Huibo; Lou, Jigang; Liu, Hao

2016-12-01

Atlantoaxial instability is a common and serious injury of the upper cervical spine. Brooks' procedure is widely used to reconstruct the unstable atlantoaxial joint. The migration into spinal cord of titanium cable and spontaneous fusion between C2 and C3 has been little reported and the management of such a patient is difficult. We describe an unusual case of fatigue failure of posterior titanium atlantoaxial cable fixation with migration into the spinal cord and spontaneous fusion between C2 and C3. A 16-year-old girl complained of cervico-occipital pain with numbness and weakness of extremities 3 months ago. The girl underwent posterior C1-C2 arthrodesis with titanium cables and autogenous iliac crest bone grafting when she was 6 years old. When presented to our emergency department, imaging revealed the cracked titanium atlantoaxial cable and the spontaneous fusion between C2 and C3. Computed tomography demonstrated a broken wire with anterior migration of the cable into the spinal cord. The patient underwent posterior approach cervical spinal surgery to remove the broken cables. She remains neurologically intact a year following the posterior approach cervical spine surgery. Brooks' posterior stabilization could not effectively control rotation at the atlantoaxial articulation, so surgeons must be aware of the potential of fatigue failure of cables as well as the possibility of its migration into the spinal cord when using Brooks' posterior stabilization. Bilateral C1 lateral mass and C2 pedicle screw fixation or transarticular screw fixation are recommended by the authors in the event of rotatory instability.

Nerve stripper-assisted sural nerve harvest.

PubMed

Hassanpour, Esmail; Yavari, Masoud; Karbalaeikhani, Ali; Saremi, Hossein

2014-03-01

Sural nerve has the favorite length and size for nerve graft interposition. Here two techniques, that is, "stocking seam" and "stair-step" or "stepladder," have been used for harvesting sural nerve. The first technique results in an unsightly scar at the posterior calf, and the latter one takes a long time to perform and exert undue traction to the graft during harvesting. The purpose of this article is to describe our experience in harvesting the sural nerve by a nerve stripper. A nerve stripper was used for harvesting sural nerve in 35 adult patients (in 6 patients, sural harvesting was done bilaterally), 27 men and 8 women. Thirty-one sural nerve harvests were done by closed technique (i.e., harvesting of sural nerve only by two incisions, one in the posterior of the lateral malleolus and the other in popliteal fossa), in 8 others by limited open technique, and in 2 cases, there was early laceration of the sural nerve at the beginning of the study. The contralateral sural nerve was harvested in one patient and medial antebrachial nerve in another by open technique. The mean length of the retrieved sural nerve was 34.5 cm in the closed technique group and 35 cm in the limited open technique group. We detected advancing Tinel's sign in all nerve stripper-assisted sural nerve harvested group members in both the closed and limited open groups. Sural nerve harvesting by the nerve stripper is a reliable and simple technique, and it is applicable as a routine technique. Applying controlled rotatory movements of the nerve stripper instead of pushing can result in satisfactory harvesting of the sural nerve without early laceration. Georg Thieme Verlag KG Stuttgart · New York.

Ultra-fast computation of electronic spectra for large systems by tight-binding based simplified Tamm-Dancoff approximation (sTDA-xTB)

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

Grimme, Stefan, E-mail: grimme@thch.uni-bonn.de; Bannwarth, Christoph

2016-08-07

The computational bottleneck of the extremely fast simplified Tamm-Dancoff approximated (sTDA) time-dependent density functional theory procedure [S. Grimme, J. Chem. Phys. 138, 244104 (2013)] for the computation of electronic spectra for large systems is the determination of the ground state Kohn-Sham orbitals and eigenvalues. This limits such treatments to single structures with a few hundred atoms and hence, e.g., sampling along molecular dynamics trajectories for flexible systems or the calculation of chromophore aggregates is often not possible. The aim of this work is to solve this problem by a specifically designed semi-empirical tight binding (TB) procedure similar to the wellmore » established self-consistent-charge density functional TB scheme. The new special purpose method provides orbitals and orbital energies of hybrid density functional character for a subsequent and basically unmodified sTDA procedure. Compared to many previous semi-empirical excited state methods, an advantage of the ansatz is that a general eigenvalue problem in a non-orthogonal, extended atomic orbital basis is solved and therefore correct occupied/virtual orbital energy splittings as well as Rydberg levels are obtained. A key idea for the success of the new model is that the determination of atomic charges (describing an effective electron-electron interaction) and the one-particle spectrum is decoupled and treated by two differently parametrized Hamiltonians/basis sets. The three-diagonalization-step composite procedure can routinely compute broad range electronic spectra (0-8 eV) within minutes of computation time for systems composed of 500-1000 atoms with an accuracy typical of standard time-dependent density functional theory (0.3-0.5 eV average error). An easily extendable parametrization based on coupled-cluster and density functional computed reference data for the elements H–Zn including transition metals is described. The accuracy of the method termed sTDA-xTB is first benchmarked for vertical excitation energies of open- and closed-shell systems in comparison to other semi-empirical methods and applied to exemplary problems in electronic spectroscopy. As side products of the development, a robust and efficient valence electron TB method for the accurate determination of atomic charges as well as a more accurate calculation scheme of dipole rotatory strengths within the Tamm-Dancoff approximation is proposed.« less

Interaction of somatoform and vestibular disorders

PubMed Central

Best, C; Eckhardt‐Henn, A; Diener, G; Bense, S; Breuer, P; Dieterich, M

2006-01-01

Background The high coincidence of organic vestibular and somatoform vertigo syndromes has appeared to support pathogenic models showing a strong linkage between them. It was hypothesised that a persisting vestibular dysfunction causes the development of anxiety disorders. Objective To determine the relation between vestibular deficits and somatoform vertigo disorders in an interdisciplinary prospective study. Methods Participants were divided into eight diagnostic groups: healthy volunteers (n = 26) and patients with benign paroxysmal positioning vertigo (BPPV, n = 11), vestibular neuritis (n = 11), Menière's disease (n = 7), vestibular migraine (n = 15), anxiety (n = 23), depression (n = 12), or somatoform disorders (n = 22). Neuro‐otological diagnostic procedures included electro‐oculography with rotatory and caloric testing, orthoptic examination with measurements of subjective visual vertical (SVV) and ocular torsion, and a neurological examination. Psychosomatic diagnostic procedures comprised interviews and psychometric instruments. Results Patients with BPPV (35.3%) and with vestibular neuritis (52.2%) had pathological test values on caloric irrigation (p<0.001). Otolith dysfunction with pathological tilts of SVV and ocular torsion was found only in patients with vestibular neuritis (p<0.001). Patients with Menière's disease, vestibular migraine, and psychiatric disorders showed normal parameters for vestibular testing but pathological values for psychometric measures. There was no correlation between pathological neurological and pathological psychometric parameters. Conclusions High anxiety scores are not a result of vestibular deficits or dysfunction. Patients with Menière's disease and vestibular migraine but not vestibular deficits showed the highest psychiatric comorbidity. Thus the course of vertigo syndromes and the possibility of a pre‐existing psychopathological personality should be considered pathogenic factors in any linkage between organic and psychometric vertigo syndromes. PMID:16614028

Perspective of Spanish medical students regarding undergraduate education in infectious diseases, bacterial resistance and antibiotic use.

PubMed

Sánchez-Fabra, David; Dyar, Oliver J; Del Pozo, José Luis; Amiguet, Juan Antonio; Colmenero, Juan de Dios; Fariñas, María Del Carmen; López-Medrano, Francisco; Portilla, Joaquín; Praena, Julia; Torre-Cisneros, Julián; Rodríguez-Baño, Jesús; Pulcini, Céline; Paño-Pardo, José Ramón

2018-02-08

One of the main tools to optimize antibiotics use is education of prescribers. The aim of this article is to study undergraduate education in the field of infectious diseases, antimicrobial resistance and antibiotic stewardship from the perspective of Spanish medical students. An anonymous online questionnaire was distributed among sixth grade students using different channels in Europe, within the ESGAP Student-Prepare survey. The questionnaire included 45 questions about knowledge, attitudes and perceptions about diagnosis, bacterial resistance, use of antibiotics and undergraduate training in infectious diseases. We present here the Spanish results. A total of 441 surveys were received from 21 medical schools. A total of 374 responses (84.8%) were obtained from the 8 most represented faculties, with a response rate of 28.9%. Most students felt adequately prepared to identify clinical signs of infection (418; 94.8%) and to accurately interpret laboratory tests (382; 86.6%). A total of 178 (40.4%) acknowledged being able to choose an antibiotic with confidence without consulting books or guidelines. Only 107 (24.3%) students considered that they had received sufficient training in judicious use of antibiotics. Regarding learning methods, the discussion of clinical cases, infectious diseases units rotatories and small group workshops were considered the most useful, being evaluated favorably in 76.9%, 76% and 68.8% of the cases. Medical students feel more confident in the diagnosis of infectious diseases than in antibiotic treatment. They also feel the need to receive more training in antibiotics and judicious antibiotic use. Copyright © 2018 Elsevier España, S.L.U. and Sociedad Española de Enfermedades Infecciosas y Microbiología Clínica. All rights reserved.

[Operative treatment of sacroiliac joint fracture and dislocation in Tile C pelvic fracture with Colorado 2 system].

PubMed

Liu, Shuping; Zhou, Qing; Liu, Yuehong; Chen, Xi; Zhou, Yu; Zhang, Desheng; Fang, Zhi; Xu, Wei

2011-12-01

To explore the effectiveness of Colorado 2 system in the stability reconstruction of sacroiliac joint fracture and dislocation in Tile C pelvic fracture. Between February 2009 and January 2011, 8 cases of Tile C pelvic fracture were treated with Colorado 2 system. There were 3 males and 5 females with an average age of 34.4 years (range, 22-52 years). Fractures were caused by traffic accident in 3 cases, by falling from height in 3 cases, and by crash of heavy object in 2 cases. According to Tile classification, 5 cases were classified as C1-2, 2 cases as C1-3, and 1 case as C2. The time between injury and operation was 5-10 days (mean, 7 days). After skeletal traction reduction, Colorado 2 system was used to fix sacroiliac joint, and reconstruction plate or external fixation was selectively adopted. The postoperative X-ray films showed that the reduction of vertical and rotatory dislocation was satisfactory, posterior pelvic ring achieved effective stability. All the incisions healed by first intention, and no blood vessel or nerve injury occurred. Eight patients were followed up 6-24 months (mean, 12 months). No loosening or breakage of internal fixation was observed and no re-dislocation of sacroiliac joint occurred. The bone healing time was 6-12 months (mean, 9 months). According to Majeed's functional criterion, the results were excellent in 5 cases, good in 2 cases, and fair in 1 case at last follow-up. Colorado 2 system could provide immediate stability of pelvic posterior ring and good maintenance of reduction effect, which is an effective method in the therapy of sacroiliac joint fracture and dislocation in Tile C pelvic fracture.

On the origin of pure optical rotation in twisted-cross metamaterials

PubMed Central

Barr, Lauren E.; Díaz-Rubio, Ana; Tremain, Ben; Carbonell, Jorge; Sánchez-Dehesa, José; Hendry, Euan; Hibbins, Alastair P.

2016-01-01

We present an experimental and computational study of the response of twisted-cross metamaterials that provide near dispersionless optical rotation across a broad band of frequencies from 19 GHz to 37 GHz. We compare two distinct geometries: firstly, a bilayer structure comprised of arrays of metallic crosses where the crosses in the second layer are twisted about the layer normal; and secondly where the second layer is replaced by the complementary to the original, i.e. an array of cross-shaped holes. Through numerical modelling we determine the origin of rotatory effects in these two structures. In both, pure optical rotation occurs in a frequency band between two transmission minima, where alignment of electric and magnetic dipole moments occurs. In the cross/cross metamaterial, the transmission minima occur at the symmetric and antisymmetric resonances of the coupled crosses. By contrast, in the cross/complementary-cross structure the transmission minima are associated with the dipole and quadrupole modes of the cross, the frequencies of which appear intrinsic to the cross layer alone. Hence the bandwidth of optical rotation is found to be relatively independent of layer separation. PMID:27457405

Modeling human vestibular responses during eccentric rotation and off vertical axis rotation

NASA Technical Reports Server (NTRS)

Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

1995-01-01

A mathematical model has been developed to help explain human multi-sensory interactions. The most important constituent of the model is the hypothesis that the nervous system incorporates knowledge of sensory dynamics into an "internal model" of these dynamics. This internal model allows the nervous system to integrate the sensory information from many different sensors into a coherent estimate of self-motion. The essence of the model is unchanged from a previously published model of monkey eye movement responses; only a few variables have been adjusted to yield the prediction of human responses. During eccentric rotation, the model predicts that the axis of eye rotation shifts slightly toward alignment with gravito-inertial force. The model also predicts that the time course of the perception of tilt following the acceleration phase of eccentric rotation is much slower than that during deceleration. During off vertical axis rotation (OVAR) the model predicts a small horizontal bias along with small horizontal, vertical, and torsional oscillations. Following OVAR stimulation, when stopped right- or left-side down, a small vertical component is predicted that decays with the horizontal post-rotatory response. All of the predictions are consistent with measurements of human responses.

Dorsal light response and changes of its responses under varying acceleration conditions

NASA Astrophysics Data System (ADS)

Watanabe, S.; Takabayashi, A.; Takagi, S.; von Baumgarten, R.; Wetzig, J.

In order to improve our understanding about functions of the gravity sensors, we have conducted four experiments in goldfish: 1) To define the effect of visual information influx on the static labyrinthine response, the dorsal light response (DLR) which had been proposed by von Holst as a model for postural adjustment in fish was reexamined with a newly designed, rotatory illumination device. The fish responded to illumination from the upper half of the visual field and a narrow range around 180 degrees of the lower half visual field. The maximal tilting angle of normal fish was about 40 degrees under horizontal illumination. 2) Under the changes of the gravito-inertial force level produced by a linear sled, the threshold of the gravity sensors was determined from postural adjustment responses. 3) Under hypogravic conditions during the parabolic flight of an airplane, the light-dependent behavior was investigated in intact and labyrinthectomized goldfish. 4) As one of the most likely candidates of the neural centers for the DLR, the valvula cerebelli, which receives its visual information not through the optic tectum but through the pretectal areas, is confirmed by the brain lesion experiments.

Psychopathological symptoms, social skills, and personality traits: a study with adolescents.

PubMed

Landazabal, Maite Garaigordobil

2006-11-01

The purpose of this study is two-fold: (a) to study the concomitant relationships between psychopathological symptoms, cooperation, social skills, and other personality traits; and (b) to identify the predictive variables of psychopathological symptoms. The sample consists of 322 adolescents aged 14 to 17 years old. This study uses correlational methodology. In order to assess psychopathological symptoms, cooperation, social skills, and personality traits, the following scales are used: the Symptom Checklist (SCL-90-R; Derogatis, 1983), the Cooperativeness Scale (CS; Rigby, Cox, and Black, 1997), the MESSY social skills scale (Matson, Rotatori, and Helsel, 1983), and the TPT Personality Test (Corral, Pamos, Pereña, and& Seisdedos, 2002). Pearson coefficients suggest that adolescents with many psychopathological symptoms have low levels of cooperative behaviors and social skills. They also score high in inappropriate assertiveness, impulsiveness, overconfidence, and jealousy-withdrawal and have low levels of emotional stability, sociability, and responsibility. Through multiple regression analyses, the following variables were identified as predictors of psychopathological symptoms: jealousy-withdrawal, low social integration, impulsiveness, and low self-concept. The role played by intervention programs promoting socio-emotional development to prevent psychopathological symptoms and enhance mental health is discussed.

The Morel-Lavallée lesion revisited: management in spinopelvic dissociation.

PubMed

Dodwad, Shah Nawaz M; Niedermeier, Steven R; Yu, Elizabeth; Ferguson, Tania A; Klineberg, Eric O; Khan, Safdar N

2015-06-01

The Morel-Lavallée lesion occurs from a compression and shear force that usually separates the skin and subcutaneous tissue from the underlying muscular fascia. A dead space is created that becomes filled with blood, liquefied fat, and lymphatic fluid from the shearing of vasculature and lymphatics. If not treated appropriately, these lesions can become infected, cause tissue necrosis, or form chronic seromas. To review appropriate identification and treatment of Morel-Lavallée lesions in spinopelvic dissociation patients. Uncontrolled case series. Retrospective review of medical records. No funding was received in support of this study. The authors report no conflicts of interest. We present four cases of patients with traumatic spinopelvic dissociation. All had concomitant lumbosacral Morel-Lavallée lesions. All four trauma patients suffered traumatic spinopelvic dissociation with concomitant lumbosacral Morel-Lavallée lesions. Appropriate treatment included irrigation and debridement, drainage, antibiotics, and vacuum-assisted wound closure. Our series reflects an association of Morel-Lavallée lesion in spinopelvic dissociation trauma patients. Possibly, the rotatory injury that occurs at the spinopelvic junction creates a shear force to form the Morel-Lavallée lesion. When presented with a spinopelvic dissociation patient, one should be prepared to treat a Morel-Lavallée lesion. Copyright © 2015 Elsevier Inc. All rights reserved.

Binocular Interactions Underlying the Classic Optomotor Responses of Flying Flies

PubMed Central

Duistermars, Brian J.; Care, Rachel A.; Frye, Mark A.

2012-01-01

In response to imposed course deviations, the optomotor reactions of animals reduce motion blur and facilitate the maintenance of stable body posture. In flies, many anatomical and electrophysiological studies suggest that disparate motion cues stimulating the left and right eyes are not processed in isolation but rather are integrated in the brain to produce a cohesive panoramic percept. To investigate the strength of such inter-ocular interactions and their role in compensatory sensory–motor transformations, we utilize a virtual reality flight simulator to record wing and head optomotor reactions by tethered flying flies in response to imposed binocular rotation and monocular front-to-back and back-to-front motion. Within a narrow range of stimulus parameters that generates large contrast insensitive optomotor responses to binocular rotation, we find that responses to monocular front-to-back motion are larger than those to panoramic rotation, but are contrast sensitive. Conversely, responses to monocular back-to-front motion are slower than those to rotation and peak at the lowest tested contrast. Together our results suggest that optomotor responses to binocular rotation result from the influence of non-additive contralateral inhibitory as well as excitatory circuit interactions that serve to confer contrast insensitivity to flight behaviors influenced by rotatory optic flow. PMID:22375108

Synergistic effects of bioremediation and electrokinetics in the remediation of petroleum-contaminated soil.

PubMed

Guo, Shuhai; Fan, Ruijuan; Li, Tingting; Hartog, Niels; Li, Fengmei; Yang, Xuelian

2014-08-01

The present study evaluated the coupling interactions between bioremediation (BIO) and electrokinetics (EK) in the remediation of total petroleum hydrocarbons (TPH) by using bio-electrokinetics (BIO-EK) with a rotatory 2-D electric field. The results demonstrated an obvious positive correlation between the degradation extents of TPH and electric intensity both in the EK and BIO-EK tests. The use of BIO-EK showed a significant improvement in degradation of TPH as compared to BIO or EK alone. The actual degradation curve in BIO-EK tests fitted well with the simulated curve obtained by combining the degradation curves in BIO- and EK-only tests during the first 60 d, indicating a superimposed effect of biological degradation and electrochemical stimulation. The synergistic effect was particularly expressed during the later phase of the experiment, concurrent with changes in the microbial community structure. The community composition changed mainly according to the duration of the electric field, leading to a reduction in diversity. No significant spatial shifts in microbial community composition and bacterial numbers were detected among different sampling positions. Soil pH was uniform during the experimental process, soil temperature showed no variations between the soil chambers with and without an electric field. Copyright © 2014 Elsevier Ltd. All rights reserved.

A Low-Cost Modular Platform for Heterogeneous Data Acquisition with Accurate Interchannel Synchronization

PubMed Central

Blanco-Claraco, José Luis; López-Martínez, Javier; Torres-Moreno, José Luis; Giménez-Fernández, Antonio

2015-01-01

Most experimental fields of science and engineering require the use of data acquisition systems (DAQ), devices in charge of sampling and converting electrical signals into digital data and, typically, performing all of the required signal preconditioning. Since commercial DAQ systems are normally focused on specific types of sensors and actuators, systems engineers may need to employ mutually-incompatible hardware from different manufacturers in applications demanding heterogeneous inputs and outputs, such as small-signal analog inputs, differential quadrature rotatory encoders or variable current outputs. A common undesirable side effect of heterogeneous DAQ hardware is the lack of an accurate synchronization between samples captured by each device. To solve such a problem with low-cost hardware, we present a novel modular DAQ architecture comprising a base board and a set of interchangeable modules. Our main design goal is the ability to sample all sources at predictable, fixed sampling frequencies, with a reduced synchronization mismatch (<1 μs) between heterogeneous signal sources. We present experiments in the field of mechanical engineering, illustrating vibration spectrum analyses from piezoelectric accelerometers and, as a novelty in these kinds of experiments, the spectrum of quadrature encoder signals. Part of the design and software will be publicly released online. PMID:26516865

Studies of the underlying mechanisms for optical nonlinearities of blue phase liquid crystals (Presentation Recording)

NASA Astrophysics Data System (ADS)

Chen, Chun-Wei; Khoo, Iam Choon; Zhao, Shuo; Lin, Tsung-Hsien; Ho, Tsung-Jui

2015-10-01

We have investigated the mechanisms responsible for nonlinear optical processes occurring in azobenzene-doped blue phase liquid crystals (BPLC), which exhibit two thermodynamically stable BPs: BPI and BPII. In coherent two wave-mixing experiments, a slow (minutes) and a fast (few milliseconds) side diffractions are observed. The underlying mechanisms were disclosed by monitoring the dynamics of grating formation and relaxation as well as by some supplementary experiments. We found the photothermal indexing and dye/LC intermolecular torque leading to lattice distortion to be the dominant mechanisms for the observed nonlinear response in BPLC. Moreover, the response time of the nonlinear optical process varied with operating phase. The rise time of the thermal indexing process was in good agreement with our findings on the temperature dependence of BP refractive index: τ(ISO) > τ(BPI) > τ(BPII). The relaxation time of the torque-induced lattice distortion was analogue to its electrostriction counterpart: τ'(BPI) > τ'(BPII). In a separate experiment, lattice swelling with selective reflection of <110> direction changed from green to red was also observed. This was attributable to the isomerization-induced change in cholesteric pitch, which directly affects the lattice spacing. The phenomenon was confirmed by measuring the optical rotatory power of the BPLC.

New Design for Rapid Prototyping of Digital Master Casts for Multiple Dental Implant Restorations.

PubMed

Romero, Luis; Jiménez, Mariano; Espinosa, María Del Mar; Domínguez, Manuel

2015-01-01

This study proposes the replacement of all the physical devices used in the manufacturing of conventional prostheses through the use of digital tools, such as 3D scanners, CAD design software, 3D implants files, rapid prototyping machines or reverse engineering software, in order to develop laboratory work models from which to finish coatings for dental prostheses. Different types of dental prosthetic structures are used, which were adjusted by a non-rotatory threaded fixing system. From a digital process, the relative positions of dental implants, soft tissue and adjacent teeth of edentulous or partially edentulous patients has been captured, and a maser working model which accurately replicates data relating to the patients oral cavity has been through treatment of three-dimensional digital data. Compared with the conventional master cast, the results show a significant cost savings in attachments, as well as an increase in the quality of reproduction and accuracy of the master cast, with the consequent reduction in the number of patient consultation visits. The combination of software and hardware three-dimensional tools allows the optimization of the planning of dental implant-supported rehabilitations protocol, improving the predictability of clinical treatments and the production cost savings of master casts for restorations upon implants.

Using an Elastic Band Device After a Severe Obstetric Pubic Symphyseal Separation: Clinical and Imaging Evaluation.

PubMed

Lasbleiz, Jeremy; Sevestre, François-Xavier; Moquet, Pierre-Yves

2017-09-01

Severe separation of the pubic symphysis is a rare delivery complication. Facing this pathology, we decided to study a new elastic band device. To evaluate the elastic band device, clinical (pain-rated) and imaging (magnetic resonance imaging and radiography) evaluations with and without the device were performed. The elastic band device is a European Conformity-certified medical device, which is made of neoprene straps, that reduces the mobility of the pelvis and the use of the internal rotator muscles. Once the elastic band device was in place, on postpartum day 1, radiography showed a decrease of the pubic width from 41 to 12 mm. Furthermore, pain decreased from 10 of 10 to 2 of 10 in 2 days, allowing the patient to ambulate and avoid surgery. After 1 month, the pubic width (6 mm) and anatomy were recovered but minor pain was still present with hip rotatory movements. The elastic band device was worn 24 hours a day from postpartum days 1-90 and 12 hours a day from postpartum days 90 to 150; afterward, the patient returned to normal life without the elastic band device. Use of an elastic band device was associated with a reduction of the pubic width and pain associated after obstetric pubic symphysis separation.

A case report of HTLV-I associated myelopathy presenting with cerebellar ataxia and nystagmus.

PubMed

Taki, Masakatsu; Nin, Fumiaki; Hasegawa, Tatsuhisa; Sakaguchi, Hirofumi; Suzuki, Toshihiro; Hisa, Yasuo; Azuma, Yumiko; Nakagawa, Masanori

2011-06-01

HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP) is characterized by spastic paraparesis in the lower extremities, and urinary disturbance. HAM/TSP has also been less frequently associated with cerebellar syndromes and nystagmus. We report a case of HAM/TSP presenting with cerebellar ataxia and nystagmus. The patient was a 73-year-old woman who was born in southern Japan. At age 41, she developed pain and spasticity in the bilateral lower limbs and gradually progressive gait disturbance. At age 57, she was diagnosed with HAM/TSP based on spastic paraparesis in the lower limbs, urinary disturbance and positive anti HTLV-I antibody in serum and cerebrospinal fluid. In June 2008, she was referred to our university and hospitalized for rehabilitation. Twenty days later, she experienced rotatory vertigo sensation. Magnetic resonance imaging revealed pontocerebellar atrophy. The patient presented with cerebellar signs in the upper limbs, gaze-evoked nystagmus in the sitting position and right-beating horizontal nystagmus in the supine and head-hanging positions. Electronystagmography (ENG) showed horizontal saccadic overshoot dysmetria and horizontal saccadic pursuit. Nystagmus is rare among the literature on HAM/TSP. ENG is helpful to evaluate and confirm the cerebellar syndromes of HAM/TSP. Copyright © 2010. Published by Elsevier Ireland Ltd.

Description of the Posterolateral Rotatory Drawer Maneuver for the Identification of Posterolateral Corner Injury

PubMed Central

Angelini, Fábio Janson; Bonadio, Marcelo Batista; Helito, Camilo Partezani; da Mota e Albuquerque, Roberto Freire; Pécora, José Ricardo; Camanho, Gilberto Luis

2014-01-01

Injury to the posterolateral corner (PLC) is difficult to diagnose; most lesions of this type are included within the context of complex knee injuries. Study of the posterolateral complex is growing in importance because of the complex instability generated by these injuries. Although various physical examination tests are described for the diagnosis of PLC lesions, in 72% of cases these lesions are not identified at their initial presentation, which shows the difficulty in both performing these tests and interpreting the results. The maneuver described in this report is performed by executing external rotation of the leg. With the thumb of the proximally positioned hand, the examiner evaluates the positioning of the lateral tibial plateau in relation to the femoral condyle. With this maneuver, in lesions of the PLC and particularly lesions of its external rotation–restricting structures, we observe external rotation of the tibia and posterior subluxation of the lateral tibial plateau that cause the anterior edge of the tibial plateau to be posteriorized in relation to the anterior edge of the lateral femoral condyle. The idea behind this maneuver is not to eliminate the use of other tests but, rather, to add it to a diagnostic arsenal that still has interpretation flaws. PMID:24904781

Isolation, characterization, and complementation of a motility mutant of Spiroplasma citri.

PubMed Central

Jacob, C; Nouzières, F; Duret, S; Bové, J M; Renaudin, J

1997-01-01

The helical mollicute Spiroplasma citri, when growing on low-agar medium, forms fuzzy colonies with occasional surrounding satellite colonies due to the ability of the spiroplasmal cells to move through the agar matrix. In liquid medium, these helical organisms flex, twist, and rotate rapidly. By using Tn4001 insertion mutagenesis, a motility mutant was isolated on the basis of its nondiffuse, sharp-edged colonies. Dark-field microscopy observations revealed that the organism flexed at a low frequency and had lost the ability to rotate about the helix axis. In this mutant, the transposon was shown to be inserted into an open reading frame encoding a putative polypeptide of 409 amino acids for which no significant homology with known proteins was found. The corresponding gene, named scm1, was recovered from the wild-type strain and introduced into the motility mutant by using the S. citri oriC plasmid pBOT1 as the vector. The appearance of fuzzy colonies and the observation that spiroplasma cells displayed rotatory and flexional movements showed the motile phenotype to be restored in the spiroplasmal transformants. The functional complementation of the motility mutant proves the scm1 gene product to be involved in the motility mechanism of S. citri. PMID:9244268

Do elite athletes exhibit enhanced proprioceptive acuity, range and strength of knee rotation compared with non-athletes?

PubMed

Muaidi, Q I; Nicholson, L L; Refshauge, K M

2009-02-01

The aims of this study were to compare proprioception in knee rotation in Olympic-level soccer players (N=18) with non-athletes (N=18), to explore between-limb differences in soccer players, and examine correlations between proprioception and years of playing, function, physical measures and skill level. The knee rotatory kinaesthetic device was used to present stimuli of different magnitudes to determine proprioceptive acuity for internal and external active rotation, and to measure active and passive rotation range of motion (ROM). Knee rotation strength was measured using a dynamometer. Proprioceptive acuity of the athletes was significantly (P=0.004) better than that of the non-athletes. Athletes displayed significantly less passive ROM (P=0.001), higher isometric muscle strength (P=0.006) and greater hop for distance (P=0.001) than non-athletes. No significant between-limb differences were found in the athletes in any objective outcome measure. Internal rotation proprioceptive acuity was negatively correlated with coach-rated ball skill (r=-0.52) and positively correlated with internal rotation ROM (r=0.59). Our findings suggest that highly trained athletes possess enhanced proprioceptive acuity and muscle strength that may be inherent, or may develop as a result of long-term athletic training.

Recent advances in orthostatic hypotension presenting orthostatic dizziness or vertigo.

PubMed

Kim, Hyun-Ah; Yi, Hyon-Ah; Lee, Hyung

2015-11-01

Orthostatic hypotension (OH), a proxy for sympathetic adrenergic failure, is the most incapacitating sign of autonomic failure. Orthostatic dizziness (OD) is known to be the most common symptom of OH. However, recent studies have demonstrated that 30-39 % of patients with OH experienced rotatory vertigo during upright posture (i.e., orthostatic vertigo, OV), which challenges the dogma that OH induces dizziness and not vertigo. A recent population-based study on spontaneously occurring OD across a wide age range showed that the one-year and lifetime prevalence of OD was 10.9 and 12.5 %, respectively. Approximately 83 % of patients with OD had at least one abnormal autonomic function test result. So far, 11 subtypes of OD have been proposed according to the pattern of autonomic dysfunction, and generalized autonomic failure of sympathetic adrenergic and parasympathetic cardiovagal functions was the most common type. Four different patterns of OH, such as classic, delayed, early, and transient type have been found in patients with OD. The head-up tilt test and Valsalva maneuver should be performed for a comprehensive evaluation of sympathetic adrenergic failure in patients with OD/OV. This review summarizes current advances in OH presenting OD/OV, with a particular focus on the autonomic dysfunction associated with OD.

Kaj Ulrik Linderstrøm-Lang (1896-1959).

PubMed Central

Schellman, J. A.; Schellman, C. G.

1997-01-01

The Carlsberg Laboratory in Copenhagen has had a long tradition of outstanding science. At the time covered by this discussion, Kjeldahl, Sørensen, and Linderstrøm-Lang had been consecutive directors of the Chemical Laboratory for 83 years. Lang's inspired leadership began in the 1930s with a number of innovations (study of metabolism in single cells, titrations in non-aqueous solvents, relation of proteolysis to structure) but it was not until the early 1950s that Denmark had sufficiently recovered from the war for the laboratory to enter world science again. During World War II, Lang had been active in the Danish resistance movement. After the war, a number of major advances were being made that would revolutionize the field of protein chemistry (Pauling and Corey's H-bonded structures, Sanger's sequencing techniques, chromatography, Watson and Crick structures, modern instrumentation). The time for the new field of the physical biochemistry of proteins had arrived. Lang, with his broad experience, adventurous spirit, and genius for innovation, created an environment that was ideal for the convergence of these disconnected advances into a uniform science. The emphasis was to be on quantitative measurements on proteins in solution with interpretations based on molecular structures. During an all-too-brief period of time, Lang's laboratory attracted a large fraction of those who were destined to be the leaders of the next generation of protein chemists. At this time, the Carlsberg Laboratory was probably the most scientifically exciting environment for a protein chemist. The methods developed at that time-hydrogen exchange, limited proteolysis, optical rotatory dispersion, volume changes accompanying protein reactions, automatic titrations-are still all in common use and many of the visitors to the laboratory in that period and their students are still playing major roles in protein research. Lang's other qualities should not be ignored. He was not only a great scientist but also a musician, raconteur, artist, and an exceptionally warm and compassionate human being. PMID:9144781

Kaj Ulrik Linderstrøm-Lang (1896-1959).

PubMed

Schellman, J A; Schellman, C G

1997-05-01

The Carlsberg Laboratory in Copenhagen has had a long tradition of outstanding science. At the time covered by this discussion, Kjeldahl, Sørensen, and Linderstrøm-Lang had been consecutive directors of the Chemical Laboratory for 83 years. Lang's inspired leadership began in the 1930s with a number of innovations (study of metabolism in single cells, titrations in non-aqueous solvents, relation of proteolysis to structure) but it was not until the early 1950s that Denmark had sufficiently recovered from the war for the laboratory to enter world science again. During World War II, Lang had been active in the Danish resistance movement. After the war, a number of major advances were being made that would revolutionize the field of protein chemistry (Pauling and Corey's H-bonded structures, Sanger's sequencing techniques, chromatography, Watson and Crick structures, modern instrumentation). The time for the new field of the physical biochemistry of proteins had arrived. Lang, with his broad experience, adventurous spirit, and genius for innovation, created an environment that was ideal for the convergence of these disconnected advances into a uniform science. The emphasis was to be on quantitative measurements on proteins in solution with interpretations based on molecular structures. During an all-too-brief period of time, Lang's laboratory attracted a large fraction of those who were destined to be the leaders of the next generation of protein chemists. At this time, the Carlsberg Laboratory was probably the most scientifically exciting environment for a protein chemist. The methods developed at that time-hydrogen exchange, limited proteolysis, optical rotatory dispersion, volume changes accompanying protein reactions, automatic titrations-are still all in common use and many of the visitors to the laboratory in that period and their students are still playing major roles in protein research. Lang's other qualities should not be ignored. He was not only a great scientist but also a musician, raconteur, artist, and an exceptionally warm and compassionate human being.

Fractures of the manubrium sterni: treatment options and a possible classification of different types of fractures

PubMed Central

Krinner, Sebastian; Oppel, Pascal; Grupp, Sina; Schulz-Drost, Melanie; Hennig, Friedrich F.; Langenbach, Andreas

2018-01-01

Background Sternum fractures are mostly located on the sternal corpus, seldom on the manubrium. Fractures of the sternal manubrium are, however, more frequently associated with severe concomitant injuries of thoracic organs, and therefore deserve special attention. In addition, in its function as a capstone in between the anterior chest wall and the shoulder girdle, it is exposed to a multiplicity of forces. Therefore the questions arise what types of fractures are observed in today’s clinical practice, how to classify them and which treatment options are available. This study reports on different types of fractures which involve the manubrium sterni. Methods Between January 2012 and October 2014, data was collected from all severely injured patients (ISS ≥16), which received a CT scan of the thorax in our Level-I-Trauma Center and retrospectively analyzed concerning sternal fractures. Fracture type, collateral injuries, age, and information about the circumstances of the accident were noted. Results Of 890 evaluable patients, 154 (17.3%) had a fracture of the sternum and 23 (2.6%) of the manubrium. Fractures of the manubrium appeared in following types: A-type—transverse fracture (n=11) in 1st intercostal space by direct blunt trauma or flexion of the torso with sagittal instability; B-type—oblique fracture (n=9) by seat belt injury with rotatory instability; C-type—combined, more fragmentary fracture (n=3) by direct blunt trauma with simultaneous flexion of the torso and multi directional instability. Fractures only little dislocation were treated conservatively, and unstable fractures were surgically stabilized (n=10). Conclusions In summary, three main types of fractures could be found. A-type fractures were stabilized with a longitudinal plate osteosynthesis and B-type fractures with transverse positioned plates. To treat complex C-type fractures, plates with a T- or H-form could be a good solution. Level of evidence: Level III retrospective prognostic cohort study PMID:29707289

Digestate as nutrient source for biomass production of sida, lucerne and maize

NASA Astrophysics Data System (ADS)

Bueno Piaz Barbosa, Daniela; Nabel, Moritz; Horsch, David; Tsay, Gabriela; Jablonowski, Nicolai

2014-05-01

Biogas as a renewable energy source is supported in many countries driven by climate and energy policies. Nowadays, Germany is the largest biogas producer in the European Union. A sustainable resource management has to be considered within this growing scenario of biogas production systems and its environmental impacts. In this respect, studies aiming to enhance the management of biogas residues, which represents a valuable source of nutrients and organic fertilization, are needed. Our objective was to evaluate the digestate (biogas residue after fermentation process) application as nutrient source for biomass production of three different plants: sida (Sida hermaphrodita - Malvaceae), lucerne (Medicago sativa - Fabaceae) and maize (Zea mays - Poaceae). The digestate was collected from an operating biogas facility (fermenter volume 2500m³, ADRW Natur Power GmbH & Co.KG Titz/Ameln, Germany) composed of maize silage as the major feedstock, and minor amounts of chicken manure, with a composition of 3,29% N; 1,07% P; 3,42% K; and 41,2% C. An arable field soil (Endogleyic Stagnosol) was collected from 0-30 cm depth and 5 mm sieved. The fertilizer treatments of the plants were established in five replicates including digestate (application amount equivalent to 40 t ha-1) and NPK fertilizer (application amount equivalent to 200:100:300 kg ha-1) applications, according to the recommended agricultural doses, and a control (no fertilizer application). The digestate and the NPK fertilizer were thoroughly mixed with the soil in a rotatory shaker for 30 min. The 1L pots were filled with the fertilized soil and the seedlings were transplanted and grown for 30 days under greenhouse conditions (16 h day/8 h night: 24ºC/18ºC; 60% air humidity). After harvesting, the leaf area was immediately measured, and the roots were washed to allow above and below-ground biomass determination. Subsequently, shoots and roots were dried at 60ºC for 48 hours. The biomass and leaf area of sida, lucerne and maize presented similar performance for both digestate and the NPK fertilizer applications, which were greater than the control, showing a positive fertilizing effect of the digestate for plant biomass production. Considering the biomass production obtained with the digestate application for sida, lucerne and maize, the results give support for further field experiments which aim to evaluate the fertilizing and conditioning effect of digestates.

Anti-rheumatoid Activity of Secondary Metabolites Produced by Endophytic Chaetomium globosum

PubMed Central

Abdel-Azeem, Ahmed M.; Zaki, Sherif M.; Khalil, Waleed F.; Makhlouf, Noha A.; Farghaly, Lamiaa M.

2016-01-01

The aim of the present study was to investigate the anti-rheumatoid activity of secondary metabolites produced by endophytic mycobiota in Egypt. A total of 27 endophytic fungi were isolated from 10 dominant medicinal plant host species in Wadi Tala, Saint Katherine Protectorate, arid Sinai, Egypt. Of those taxa, seven isolates of Chaetomium globosum (CG1–CG7), being the most frequent taxon, were recovered from seven different host plants and screened for production of active anti-inflammatory metabolites. Isolates were cultivated on half – strength potato dextrose broth for 21 days at 28°C on a rotatory shaker at 180 rpm, and extracted in ethyl acetate and methanol, respectively. The probable inhibitory effects of both extracts against an adjuvant induced arthritis (AIA) rat model were examined and compared with the effects of methotrexate (MTX) as a standard disease-modifying anti-rheumatoid drug. Disease activity and mobility scoring of AIA, histopathology and transmission electron microscopy (TEM) were used to evaluate probable inhibitory roles. A significant reduction (P < 0.05) in the severity of arthritis was observed in both the methanolic extract of CG6 (MCG6) and MTX treatment groups 6 days after treatment commenced. The average arthritis score of the MCG6 treatment group was (10.7 ± 0.82) compared to (13.8 ± 0.98) in the positive control group. The mobility score of the MCG6 treatment group (1.50 ± 0.55) was significantly lower than that of the positive control group (3.33 ± 0.82). In contrast, the ethyl acetate extract of CG6 (EACG6) treatment group showed no improvements in arthritis and mobility scores in AIA model rats. Histopathology and TEM findings confirmed the observation. Isolate CG6 was subjected to sequencing for confirmation of phenotypic identification. The internal transcribed spacer (ITS) 1–5.8 s – ITS2 rDNA sequences obtained were compared with those deposited in the GenBank Database and registered with accession number KC811080 in the NCBI Database. The present study revealed that the methanol extract of endophytic fungus C. globosum (KC811080) recovered from maidenhair fern has an inhibitory effect on inflammation, histopathology and morphological features of rheumatoid arthritis in an AIA rat model. PMID:27703452

Male and female characteristics in vestibular testing: a step toward the selection of the best participants for space flight

NASA Astrophysics Data System (ADS)

Aust, G.; Hordinsky, J. R.; Schmelzer, B.

1980-11-01

Vestibular disturbances in connection with space flight were reported by a majority of participating astronauts and cosmonauts. These include motion sickness symptoms in the first few days of the space flight, as well as standing, gait and orientation disturbances after the return to Earth.The Aerospace Medical Community has been trying to select those people that are particularly adapted to the above stresses or that can be further adapted through training programs. As the circle of selectees extends to women, the problem arises as to whether differences between men and women exist under the conditions of space flight.In seeking answers to this question we studied a group of 42 women and 44 men, who were further subdivided according to their subjective motion sickness sensitivity, as determined by a questionnaire. Using this material, 26 men and 22 women were designated as motion sickness resistant, and 18 men and 20 women were designated as nonresistant.The vestibular test battery given these test subjects consisted of caloric, rotatory, optokinetic, vestibulo-spinal and vestibulo-vegetative testing.Because of the mixed orthostatic and vestibular problems seen after space flights, we also studied the response of the vestibular apparatus during peripheral blood pooling as induced by lower body negative pressure.The collected historical and test data are analyzed in this paper with emphasis on the relationship to motion sickness tendency.

Titanium in dentistry: historical development, state of the art and future perspectives.

PubMed

Jorge, Juliana Ribeiro Pala; Barão, Valentim Adelino; Delben, Juliana Aparecida; Faverani, Leonardo Perez; Queiroz, Thallita Pereira; Assunção, Wirley Gonçalves

2013-06-01

Titanium is a metallic element known by several attractive characteristics, such as biocompatibility, excellent corrosion resistance and high mechanical resistance. It is widely used in Dentistry, with high success rates, providing a favorable biological response when in contact with live tissues. Therefore, the objective of this study was to describe the different uses of titanium in Dentistry, reviewing its historical development and discoursing about its state of art and future perspective of its utilization. A search in the MEDLINE/PubMed database was performed using the terms 'titanium', 'dentistry' and 'implants'. The title and abstract of articles were read, and after this first screening 20 articles were selected and their full-texts were downloaded. Additional text books and manual search of reference lists within selected articles were included. Correlated literature showed that titanium is the most used metal in Implantology for manufacturing osseointegrated implants and their systems, with a totally consolidated utilization. Moreover, titanium can be also employed in prosthodontics to obtain frameworks. However, problems related to its machining, casting, welding and ceramic application for dental prosthesis are still limiting its use. In Endodontics, titanium has been used in association to nickel for manufacturing rotatory instruments, providing a higher resistance to deformation. However, although the different possibilities of using titanium in modern Dentistry, its use for prostheses frameworks still needs technological improvements in order to surpass its limitations.

[Sporangia ontogeny and sporogenesis of the lycopodium Huperzia brevifolia (Lycopodiaceae) from the high mountains of Colombia].

PubMed

Barón, Edgar Javier Rincón; Landazábal, Leidy Vivivana Gélvez; Ballesteros, Helkin Giovany Forero; Prieto, Dagoberto Arrieta; Hleap, José Sergio

2009-12-01

Huperzia brevifolia is one of the dominant species of the genus Huperzia living in paramos and superparamos from the Colombian Andes. A detailed study of the sporangium's ontogeny and sporogenesis was carried out using specimens collected at 4200m above sea level, in Parque Natural Nacional El Cocuy, Colombia. Small pieces of caulinar axis bearing sporangia were fixed, dehydrated, paraffin embedded, sectioned in a rotatory microtome, and stained using the common Safranin O-Fast Green technique; handmade cross sections were also made, stained with aqueous Toluidine Blue (TBO). The sporangia develops basipetally, a condition that allows observation of all the developmental stages taking place throughout the caulinar axis of adult plants. Each sporangium originates from a group of epidermal cells, axilar to the microphylls. These cells undergo active mitosis, and produce new external and internal cellular groups. The sporangium wall and the tapetum originate from the external group of cells, while the internal cellular group leads to the sporogenous tissue. Meiosis occur in the sporocytes and produce simultaneous types tetrads, each one giving rise four trilete spores, with foveolate ornamentation. During the sporangium ripening, the outermost layer of the wall develops anticlinally, and inner periclinal thickenings and the innermost one perform as a secretory tapetum, which persists until the spores are completely mature. All other cellular layers colapse.

Alternation of regular and chaotic dynamics in a simple two-degree-of-freedom system with nonlinear inertial coupling.

PubMed

Sigalov, G; Gendelman, O V; AL-Shudeifat, M A; Manevitch, L I; Vakakis, A F; Bergman, L A

2012-03-01

We show that nonlinear inertial coupling between a linear oscillator and an eccentric rotator can lead to very interesting interchanges between regular and chaotic dynamical behavior. Indeed, we show that this model demonstrates rather unusual behavior from the viewpoint of nonlinear dynamics. Specifically, at a discrete set of values of the total energy, the Hamiltonian system exhibits non-conventional nonlinear normal modes, whose shape is determined by phase locking of rotatory and oscillatory motions of the rotator at integer ratios of characteristic frequencies. Considering the weakly damped system, resonance capture of the dynamics into the vicinity of these modes brings about regular motion of the system. For energy levels far from these discrete values, the motion of the system is chaotic. Thus, the succession of resonance captures and escapes by a discrete set of the normal modes causes a sequence of transitions between regular and chaotic behavior, provided that the damping is sufficiently small. We begin from the Hamiltonian system and present a series of Poincaré sections manifesting the complex structure of the phase space of the considered system with inertial nonlinear coupling. Then an approximate analytical description is presented for the non-conventional nonlinear normal modes. We confirm the analytical results by numerical simulation and demonstrate the alternate transitions between regular and chaotic dynamics mentioned above. The origin of the chaotic behavior is also discussed.

Arthrodesis of the knee with a vascularized fibular rotatory graft.

PubMed

Rasmussen, M R; Bishop, A T; Wood, M B

1995-05-01

We retrospectively reviewed the records of thirteen patients who had been managed with an arthrodesis of the knee with use of a vascularized graft from the ipsilateral fibula and fixation with an intramedullary rod. The indications for the operation included a large skeletal defect secondary to the resection of a tumor about the knee in eight patients, an infection at the site of an arthroplasty in four (with failure of a previous conventional arthrodesis in three of the four), and severe rheumatoid gonarthrosis as well as a persistent non-union of the distal part of the femur in one. The average age of the patients at the time of the operation was forty-three years (range, twenty-six to seventy-six years). Most of the patients had had multiple previous procedures (thirty-three operations had been performed in ten patients). Twelve of the thirteen patients had a solid fusion and a successful result after an average duration of follow-up of fifty-one months (range, eight to ninety-three months). The remaining patient, who had had four previous arthroplasties, had a recurrence of an infection seven months after the operation and was managed with an amputation. Six complications--including two superficial wound infections, one deep wound infection, one deep venous thrombosis, one transient peroneal-nerve palsy, and one delayed union--occurred in three patients.

Association between vestibular function and motor performance in hearing-impaired children.

PubMed

Maes, Leen; De Kegel, Alexandra; Van Waelvelde, Hilde; Dhooge, Ingeborg

2014-12-01

The clinical balance performance of normal-hearing (NH) children was compared with the balance performance of hearing-impaired (HI) children with and without vestibular dysfunction to identify an association between vestibular function and motor performance. Prospective study. Tertiary referral center. Thirty-six children (mean age, 7 yr 5 mo; range, 3 yr 8 mo-12 yr 11 mo) divided into three groups: NH children with normal vestibular responses, HI children with normal vestibular responses, and HI children with abnormal vestibular function. A vestibular test protocol (rotatory and collic vestibular evoked myogenic potential testing) in combination with three clinical balance tests (balance beam walking, one-leg hopping, one-leg stance). Clinical balance performance. HI children with abnormal vestibular test results obtained the lowest quotients of motor performance, which were significantly lower compared with the NH group (p < 0.001 for balance beam walking and one-leg stance; p = 0.003 for one-leg hopping). The balance performance of the HI group with normal vestibular responses was better in comparison with the vestibular impaired group but still significantly lower compared with the NH group (p = 0.020 for balance beam walking; p = 0.001 for one-leg stance; not significant for one-leg hopping). These results indicate an association between vestibular function and motor performance in HI children, with a more distinct motor deterioration if a vestibular impairment is superimposed to the auditory dysfunction.

Enamel microabrasion: An overview of clinical and scientific considerations

PubMed Central

Pini, Núbia Inocencya Pavesi; Sundfeld-Neto, Daniel; Aguiar, Flavio Henrique Baggio; Sundfeld, Renato Herman; Martins, Luis Roberto Marcondes; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

2015-01-01

Superficial stains and irregularities of the enamel are generally what prompt patients to seek dental intervention to improve their smile. These stains or defects may be due to hypoplasia, amelogenesis imperfecta, mineralized white spots, or fluorosis, for which enamel microabrasion is primarily indicated. Enamel microabrasion involves the use of acidic and abrasive agents, such as with 37% phosphoric acid and pumice or 6% hydrochloric acid and silica, applied to the altered enamel surface with mechanical pressure from a rubber cup coupled to a rotatory mandrel of a low-rotation micromotor. If necessary, this treatment can be safely combined with bleaching for better esthetic results. Recent studies show that microabrasion is a conservative treatment when the enamel wear is minimal and clinically imperceptible. The most important factor contributing to the success of enamel microabrasion is the depth of the defect, as deeper, opaque stains, such as those resulting from hypoplasia, cannot be resolved with microabrasion, and require a restorative approach. Surface enamel alterations that result from microabrasion, such as roughness and microhardness, are easily restored by saliva. Clinical studies support the efficacy and longevity of this safe and minimally invasive treatment. The present article presents the clinical and scientific aspects concerning the microabrasion technique, and discusses the indications for and effects of the treatment, including recent works describing microscopic and clinical evaluations. PMID:25610848

Anatomy of the anterior cruciate ligament with regard to its two bundles.

PubMed

Petersen, Wolf; Zantop, Thore

2007-01-01

The anterior cruciate ligament (ACL) consists of two major fiber bundles, namely the anteromedial and posterolateral bundle. When the knee is extended, the posterolateral bundle (PL) is tight and the anteromedial (AM) bundle is moderately lax. As the knee is flexed, the femoral attachment of the ACL becomes a more horizontal orientation; causing the AM bundle to tighten and the PL bundle to relax. There is some degree of variability for the femoral origin of the anterome-dial and posterolateral bundle. The anteromedial bundle is located proximal and anterior in the femoral ACL origin (high and deep in the notch when the knee is flexed at 90 degrees ); the posterolateral bundle starts in the distal and posterior aspect of the femoral ACL origin (shallow and low when the knee is flexed at 90 degrees ). In the frontal plane the anteromedial bundle origin is in the 10:30 clock position and the postero-lateral bundle origin in the 9:30 clock position. At the tibial insertion the ACL fans out to form the foot region. The anteromedial bundle insertion is in the anterior part of the tibial ACL footprint, the posterolateral bundle in the posterior part. While the anteromedial bundle is the primary restraint against anterior tibial translation, the posterolateral bundle tends to stabilize the knee near full extension, particularly against rotatory loads.

Triboelectric-Electromagnetic Hybrid Generator for Harvesting Blue Energy

NASA Astrophysics Data System (ADS)

Shao, Huiyun; Cheng, Ping; Chen, Ruixuan; Xie, Lingjie; Sun, Na; Shen, Qingqing; Chen, Xiaoping; Zhu, Qianqian; Zhang, Yi; Liu, Yina; Wen, Zhen; Sun, Xuhui

2018-07-01

Progress has been developed in harvesting low-frequency and irregular blue energy using a triboelectric-electromagnetic hybrid generator in recent years. However, the design of the high-efficiency, mechanically durable hybrid structure is still challenging. In this study, we report a fully packaged triboelectric-electromagnetic hybrid generator (TEHG), in which magnets were utilized as the trigger to drive contact-separation-mode triboelectric nanogenerators (CS-TENGs) and coupled with copper coils to operate rotary freestanding-mode electromagnetic generators (RF-EMGs). The magnet pairs that produce attraction were used to transfer the external mechanical energy to the CS-TENGs, and packaging of the CS-TENG part was achieved to protect it from the ambient environment. Under a rotatory speed of 100 rpm, the CS-TENGs enabled the TEHG to deliver an output voltage, current, and average power of 315.8 V, 44.6 μA, and 90.7 μW, and the output of the RF-EMGs was 0.59 V, 1.78 mA, and 79.6 μW, respectively. The cylinder-like structure made the TEHG more easily driven by water flow and demonstrated to work as a practical power source to charge commercial capacitors. It can charge a 33 μF capacitor from 0 to 2.1 V in 84 s, and the stored energy in the capacitor can drive an electronic thermometer and form a self-powered water-temperature sensing system.[Figure not available: see fulltext.

Natural Optical Activity of Chiral Epoxides: the Influence of Structure and Environment on the Intrinsic Chiroptical Response

NASA Astrophysics Data System (ADS)

Lemler, Paul M.; Craft, Clayton L.; Vaccaro, Patrick

2017-06-01

Chiral epoxides built upon nominally rigid frameworks that incorporate aryl substituents have been shown to provide versatile backbones for asymmetric syntheses designed to generate novel pharmaceutical and catalytic agents. The ubiquity of these species has motivated the present studies of their intrinsic (solvent-free) circular birefringence (CB), the measurement of which serves as a benchmark for quantum-chemical predictions of non-resonant chiroptical behavior and as a beachhead for understanding the often-pronounced mediation of such properties by environmental perturbations (e.g., solvation). The optical rotatory dispersion (or wavelength-resolved CB) of (R)-styrene oxide (R-SO) and (S,S)-phenylpropylene oxide (S-PPO) have been interrogated under ambient solvated and isolated conditions, where the latter efforts exploited the ultrasensitive techniques of cavity ring-down polarimetry. Both of the targeted systems display marked solvation effects as evinced by changes the magnitude and (in the case of R-SO) the sign of the extracted specific optical rotation, with the anomalously large response evoked from S-PPO distinguishing it from other members of the epoxide family. Linear-response calculations of dispersive optical activity have been performed at both density-functional and coupled-cluster levels of theory to unravel the structural and electronic origins of experimental findings, thereby suggesting the possible involvement of hindered torsional motion along dihedral coordinates adjoining phenyl and epoxide moieties.

Tibiofemoral forces for the native and post-arthroplasty knee: relationship to maximal laxity through a functional arc of motion.

PubMed

Manning, William A; Ghosh, Kanishka; Blain, Alasdair; Longstaff, Lee; Deehan, David John

2017-06-01

Accurate soft tissue balance must be achieved to improve functional outcome after total knee arthroplasty (TKA). Sensor-integrated tibial trials have been introduced that allow real-time measurement of tibiofemoral kinematics during TKA. This study examined the interplay between tibiofemoral force and laxity, under defined intraoperative conditions, so as to quantify the kinematic behaviour of the CR femoral single-radius knee. TKA was undertaken in eight loaded cadaveric specimens. Computer navigation in combination with sensor data defined laxity and tibiofemoral contact force, respectively, during manual laxity testing. Fixed-effect linear modelling allowed quantification of the effect for flexion angle, direction of movement and TKA implantation upon the knee. An inverse relationship between laxity and contact force was demonstrated. With flexion, laxity increased as contact force decreased under manual stress. Change in laxity was significant beyond 30° for coronal plane laxity and beyond 60° for rotatory laxity (p < 0.01). Rotational stress in mid-flexion demonstrated the greatest mismatch in inter-compartmental forces. Contact point position over the tibial sensor demonstrated paradoxical roll-forward with knee flexion. Traditional balancing techniques may not reliably equate to uniform laxity or contact forces across the tibiofemoral joint through a range of flexion and argue for the role of per-operative sensor use to aid final balancing of the knee.

Atlantoaxial rotatory fixation: part 2--new diagnostic paradigm and a new classification based on motion analysis using computed tomographic imaging.

PubMed

Pang, Dachling; Li, Veetai

2005-11-01

This is Part II of a study on atlantoaxial rotatory fixation (AARF) that aims to introduce a new diagnostic paradigm and a new classification of this condition based on motion analysis of C1C2 rotation using computed tomographic (CT) imaging. This phase of the study is possible because Part I succeeded in defining physiological C1C2 axial rotation with CT data from 21 normal children, displayed in a highly concordant composite motion curve, which is used as the normal template for the present study. AARF is defined as flagrant departure from normal motion dynamics as delineated by abnormal motion curves. The new classification is predicated on the graded amount of pathological stickiness in the restricted rotation. Forty children age 1.5 to 14 years with painful "cock-robin" necks resulting from minor trauma or otolaryngological procedures were subjected to 3 CT examinations: 1) in the presenting (P) position; 2) with the nose pointing up (P0 position); and 3) with the head forcefully turned to the opposite side as much as the patient could tolerate (P_ position). The angles made by C1 and C2 and the separation angle C1C2 degrees (C1 minus C2 degrees) were obtained as described in Part I. The test motion curve was generated by plotting C1 against C1C2 angles, and all motion curves were analyzed in the context of the normal template. Five distinct groups with highly characteristic motion curves could be identified. Group 1 (n = 5) patients showed essentially unaltered ("locked") C1C2 coupled configurations regardless of corrective counterrotation, with curves that are horizontal lines in the upper two quadrants of the template. Group 2 (n = 7) patients had reduction of the C1C2 separation angle with forced correction, but C1 could not be made to cross C2. Their curves slope downward from right to left in the upper quadrants but never traverse the x axis. Group 3 (n = 9) patients showed C1C2 crossover, but only when the head was cranked far to the opposite side. Their motion curves traverse the x axis left of C1 = -20 degrees. Groups 1, 2, and 3 motion dynamics are respectively classified as Types I, II, and III AARF in descending degree of pathological stickiness, which is in essence a resistance against closure of the C1C2 angle to counterrotation. Group 4 (n = 14) patients had normal dynamics, and Group 5 (n = 5) patients showed motion curve features between normal and Type III AARF, designated as belonging to the diagnostic gray zone, an uncertain group that may or may not revert to normal dynamics with only comfort measures. AARF can be reliably diagnosed with a simple and practical CT protocol and construction of a three-point motion curve superimposed on a reusable normal template. The type of AARF, reflective of the severity of pathological stickiness of rotation, can be identified readily by the shape of the motion curve. This system of classification is useful in selecting the best regimen of management.

Envisaging Structural Insight of a Terminally Protected Proline Dipeptide by Raman Spectroscopy and Density Functional Theory Analyses.

PubMed

Das, Supriya; Pal, Uttam; Chatterjee, Moumita; Pramanik, Sumit Kumar; Banerji, Biswadip; Maiti, Nakul C

2016-12-15

The proline residue in a protein sequence generates constraints to its secondary structure as the associated torsion angles become a part of the heterocyclic ring. It becomes more significant when two consecutive proline residues link via amide linkage and produce additional configurational constraint to a protein's folding and stability. In the current manuscript we have illustrated conformation preference of a novel dipeptide, (R)-tert-butyl 2-((S)-2-(methoxycarbonyl)pyrrolidine-1-carbonyl)pyrrolidine-1-carboxylate. The dipeptide crystallized in the orthorhombic crystalline state and produced rod-shaped macroscopic material. The analysis of the crystal coordinates showed dihedral angles (φ, ψ) of the interlinked amide groups as (+72°, -147°) and the dihedral angles (φ, ψ) produced with the next carbonyl were (-68°, +151°), indicating polyglycine II (PGII) and polyproline II (PPII)-like helix states at the N- and C-terminals, respectively. These two states, PGII and PPII, are mirror image configurations and are expected to produce similar vibration bands from the associated carbonyl groups. However, the unique atomic arrangement in the molecule produces three carbonyl groups and one of them was very specific, being part of the main peptide linkage that connects both the pyrrolidine rings. The carbonyl group in the peptide bond exhibited a Raman vibration frequency at ∼1642 cm -1 and is considered a signatory Raman marker band for the peptide bond linking two heterochiral proline residues. The carbonyl group (t-Boc) at the N-terminal of the peptide showed a characteristic vibration at ∼1685 cm -1 and the C-terminal carbonyl group as a part of the ester showed a vibration signature at a significantly high frequency (1746 cm -1 ). Conformation analyses performed with density functional theory (DFT) calculations depicted that the dipeptide was stabilized in vacuum with dihedral angles (+72°, -154°) and (-72°, +151°) at the N- and C-terminals, respectively. Molecular dynamics (MD) simulation also showed that the peptide conformation having dihedral angles around (+75°, -150°) and (-75°, +150°) at the N- and C-terminals, respectively, was reasonably stable in water. Due to unique absence of the amide N-H, the peptide was ineffective in forming any intramolecular hydrogen bonding. MD investigation, however, revealed an intermolecular hydrogen bonding interaction with the water molecules, leading to its stability in aqueous solution. Metadynamics simulation analysis of the dipeptide in water also supported the PGII-PPII-like conformation at the N- and C-terminals, respectively, as the energetically stable conformation among the other possible combinations of conformations. The possible electronic transitions along with the HOMO-LUMO analysis further depicted the stability of the dipeptide in water and their possible absorption pattern. Time-dependent density functional theory (TDDFT) analysis showed strong negative rotatory strength of the dipeptide around 210 nm in water and acetonitrile, and it could be the source of experimentally observed high-amplitude negative absorption in the circular dichroism (CD) spectra around 200-203 nm. The very weak positive band (signature) in the region at ∼228 nm in CD spectra could also be correlated to the positive rotatory strength at 228 nm observed in ECD. To test the effect of such a dipeptide on a living cell, an MTT assay was performed and the result indicated no cytotoxic effect toward human hepatocellular carcinoma Hep G2 cancer cell lines.

The Direct Insertion of the ACL Carries More Load than the Indirect Insertion

PubMed Central

Nawabi, Danyal H.; Tucker, Scott; Jones, Kristofer J.; Nguyen, Joseph; Wickiewicz, Thomas L.; Imhauser, Carl; Pearle, Andrew

2014-01-01

Objectives: Recent histological studies have shown that the ACL consists of two different structures: the direct and indirect insertions. The direct insertion is located along the lateral intercondylar ridge and the indirect insertion is ‘lower’ in the notch, adjacent to the posterior articular cartilage. The ‘lower’ position has become more popular for locating the femoral tunnel, as surgeons switch to the anteromedial (AM) portal drilling technique in order to place the graft in the region of the native footprint. However, a recent registry-based outcomes study has reported a 1.5 times higher graft failure rate for AM portal versus traditional transtibial techniques. The objective of this study was to investigate the load characteristics of the native ACL in the regions of the direct and indirect insertions. We hypothesized that the direct insertion would carry more load than the indirect insertion. Methods: Twelve cadaveric knees were mounted to a six degree of freedom robot equipped with a universal force-moment sensor. We simulated the Lachman and anterior drawer tests at 30oand 90o of flexion by applying a 134N anterior load, and the pivot shift test at 15o flexion by applying combined valgus (8Nm) and internal (4Nm) rotational moments. The kinematic pathway required to achieve these loading conditions was recorded for each intact knee. Using position control to repeat the loading paths, the robot recorded the loads for the ACL intact, ACL partially sectioned, and ACL completely sectioned states. Sectioning Protocol: The lateral intercondylar ridge and posterior articular margin was identified in each case. The 50% mark between this two areas was used to delineate the regions of the direct and indirect insertions (Fig. 1). Sectioning order was alternated between each cadaver. Footprint Digitization: The borders of the sectioned areas were digitized post-sectioning and mapped onto a computed tomography (CT) scan of each knee. The sectioning method was assessed under a blinded validation by experienced observers (TW, AP) who excluded two specimens that did not conform to the objective definitions of the sectioning method. Statistics: Loads were compared between direct and indirect locations at different flexion angles by conducting two-way repeated measures ANOVA models. Results: Under an anterior tibial load at 30o flexion, the direct insertion carried 83.9% (±7.2%) of the total ACL load compared to 16.1% (±7.2%) in the indirect insertion (p<0.001). The direct insertion also carried more load at 90o flexion (95.2% vs 4.8%; p<0.001). Under a combined rotatory load at 15o flexion, the direct insertion carried 84.2% (±4.2%)of the total ACL load compared to 15.8% (±4.2%) in the indirect insertion (p<0.001). Conclusion: The fibres in the direct insertion of the ACL carry more load than fibres in the indirect insertion. Previous studies have suggested that the direct insertion plays a major role in the mechanical link between the ACL and bone. With the current shift in emphasis towards anatomic ACL reconstruction, it may be beneficial to create the femoral tunnel within the direct insertion rather than ‘lower’ in the notch. Although further work is required in determining graft behaviour at the new insertions sites described in this study, our findings suggest that placing a graft in the region of the direct insertion may be an important consideration when adhering to the principles of anatomic ACL reconstruction.

Immunohistochemical profile of some neurotransmitters and neurotrophins in the seminiferous tubules of rats treated by lonidamine.

PubMed

Artico, M; Bronzetti, E; Saso, L; Felici, L M; D'Ambrosio, A; Forte, F; Grande, C; Ortolani, F

2007-01-01

Lonidamine (LND) or [1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid] is an anticancer and antispermatogenic drug that exerts a large number of effects on tumor cells and germ cells. Sexually mature male Sprague-Dawley rats were housed at 22 degrees C on a 12-h light/12-h dark cycle 1 week before the experiments, with free access to food and water. LND was suspended in 0.5% methylcellulose at a concentration of 10 mg/mL and administered orally at the dose of 10 mL/kg (b.w.) as a single dose. Control rats received an equal amount of vehicle. Testes were removed, fixed for 24 h in 2% glutaraldehyde and 2% paraformaldehyde in 0.1 M sodium phosphate (pH 7.2 at 22 degrees C), rinsed with the same buffer, and stored at room temperature. From each sample, a block of tissue was removed by sectioning through the organ. After dehydration in ethanol at increasing concentrations (70-100%), each block was embedded in paraffin and serial 5 mm thick sections were cut using a rotatory microtome. The immunoreactivity for NTs has been observed in spermatogonia of untreated rats, while the rats treated with LND showed an immunohistochemical localization in all the stages of germinal cells. The generally well-expressed immunoreactivity for the neurotrophins receptors in treated rats observed in our study is presumably attributable to alterations of the receptors' structure and/or expression leading to changes of the activity, affinity, localization or protein interactions that may depend on sensitization of ion channels (induced by LND). Neurotrophins (NTs) appear to be interesting proteins for the modulation of sperm maturation and motility with a prominent role for the nerve growth factor (NGF), that may exert an autocrine or paracrine role. We therefore investigated the location and distribution of immunoreactivity for some neurotransmitters (SP, VIP, CGRP, nNOS, Chat), neurotrophins (NGF, BDNF, NT-3) and their own receptors (TrKA, TrKB, TrKC, p75) in the seminiferous tubules of male rats treated by LND in the light of the literature on this topic.

A pH-responsive carboxylic β-1,3-glucan polysaccharide for complexation with polymeric guests.

PubMed

Lien, Le Thi Ngoc; Shiraki, Tomohiro; Dawn, Arnab; Tsuchiya, Youichi; Tokunaga, Daisuke; Tamaru, Shun-ichi; Enomoto, Naoya; Hojo, Junichi; Shinkai, Seiji

2011-06-07

The helix-forming nature of β-1,3-glucan polysaccharides is a characteristic that has potential for producing gene carriers, bio-nanomaterials and other chiral nanowires. Herein, carboxylic curdlan (CurCOOH) bearing the β-1,3-polyglucuronic acid structure was successfully prepared from β-1,3-glucan polysaccharide curdlan (Cur) by one-step oxidation using a 4-acetamido-TEMPO/NaClO/NaClO(2) system as the oxidant. The resulting high-molecular-weight CurCOOH was proved to bear the 6-COOH group in 100% purity. The optical rotatory dispersion (ORD) spectra indicated that the obtained CurCOOH behaves as a water-soluble single-strand in various pH aqueous media. This advantage has allowed us to use CurCOOH as a polymeric host to form various macromolecular complexes. For example, complexation of CurCOOH with single-walled carbon nanotubes (SWNTs) resulted in a water-soluble one-dimensional architecture, which formed a dispersion in aqueous solution that was stable for several months, and much more stable than SWNTs complexes of the similar negatively-charged polyacrylic acid (PAA) and polymethacrylic acid (PMAA). It was shown that in the complex, SWNTs are effectively wrapped by a small amount of CurCOOH, enabling them to avoid electrostatic repulsion. This pH-responsive CurCOOH formed a very stable complex with cationic water-soluble polythiophenes (PT-1), which was stabilized not only by the hydrophobic interaction but also by the electrostatic attraction between trimethylammonium cations in PT-1 and dissociated anionic COO(-) groups in CurCOOH. The included PT-1 became CD-active only in the neutral to basic pH region, and the positive Cotton effect suggested that the conjugated main chain is twisted in the right-handed direction. We also found that CurCOOH can interact with polycytidylic acid (poly(C)) only under high NaCl concentrations, the binding and release of which could be controlled by a change in the salt concentration. We believe, therefore, that CurCOOH bearing a dissociable COOH group can act as a new potential polymeric host to construct novel polymeric complexes applicable for gene carriers, biosensors, chiral polymer assemblies, etc.

Vestibular evoked myogenic potentials and digital vectoelectro-nystagmography's study in patients with benign paroxysmal positional vertigo

PubMed Central

Maria da Silva Lira-Batista, Marta; Schaffeln Dorigueto, Ricardo; Freitas Ganança, Cristina

2013-01-01

Summary Introduction: Benign Paroxysmal Positional Vertigo (BPPV) is a very common vestibular disorder characterized by brief but intense attacks of rotatory vertigo triggered by simple rapid movement of the head. The integrity of the vestibular pathways can be assessed using tests such as digital vectoelectronystagmography (VENG) and vestibular evoked myogenic potentials (VEMP). Aim: This study aimed to determine the VEMP findings with respect to latency, amplitude, and waveform peak to peak and the results of the oculomotor and vestibular components of VENG in patients with BPPV. Method: Although this otoneurological condition is quite common, little is known of the associated VEMP and VENG changes, making it important to research and describe these results. Results: We examined the records of 4438 patients and selected 35 charts after applying the inclusion and exclusion criteria. Of these, 26 patients were women and 9 men. The average age at diagnosis was 52.7 years, and the most prevalent physiological cause, accounting for 97.3% of cases, was ductolithiasis. There was a statistically significant association between normal hearing and mild contralateral sensorineural hearing loss. The results of the oculomotor tests were within the normal reference ranges for all subjects. Patients with BPPV exhibited symmetrical function of the semicircular canals in their synergistic pairs (p < 0.001). The caloric test showed statistically normal responses from the lateral canals. The waveforms of all patients were adequate, but the VEMP results for the data-crossing maneuver with positive positioning showed a trend toward a relationship for the left ear Lp13. There was also a trend towards an association between normal reflexes in the caloric test and the inter-peak VEMP of the left ear. It can be concluded that although there are some differences between the average levels of the VENG and VEMP results, these differences were not statistically significant. Conclusion: In conclusion, the results of audiologic assessment, hearing thresholds, positioning maneuvers, and caloric tests have no effect on the quantitative results of VEMP. Additional research is warranted to establish the relationships among VENG, VEMP, and BPPV, especially as concerns the oculomotor tests. PMID:25992006

Peak firing rates of rat anterodorsal thalamic head direction cells are higher during faster passive rotations.

PubMed

Zugaro, Michaël B; Berthoz, Alain; Wiener, Sidney I

2002-01-01

Head direction cells discharge selectively when the head of the animal is oriented in a specific direction. The goal of this study was to determine how sensory signals arising from passive rotations (e.g., triggered by vestibular stimulation and dynamic visual inputs) influence the responses of anterodorsal thalamic head direction cells in the absence of voluntary movement cues (e.g., motor command, efference copy, and associated kinesthetic signals). Three unrestrained rats consumed water from a reservoir at the center of a circular platform while passively subjected to sinusoidal rotatory oscillations at fast (153 +/- 27 degrees/s, sd) and slow (38 +/- 15 degrees/s) peak velocities. In 14 anterodorsal thalamic head direction cells, the preferred directions, angular response ranges and baseline firing rates remained stable, but the peak firing rates were, on average, 36% higher during the fast rotations (Wilcoxon matched-pairs test, p < 0.001; variation range: +11% to approximately +100%). No cell changed its peak firing rate by less than 10%, while three cells (21%) increased their peak firing rates by more than 50%. The velocity-dependent increase in peak firing rates was similar for left and right rotations, and the skewness of the directional response curves were not significantly different between left and right turns (Wilcoxon matched-pairs tests, n = 14, ns). These results show that sensory signals concerning self-movements modulate the responses of the head direction cells in the absence of active locomotion.

A Hybrid Program for Fitting Rotationally Resolved Spectra of Floppy Molecules with One Large-Amplitude Rotatory Motion and One Large-Amplitude Oscillatory Motion

PubMed Central

Kleiner, Isabelle; Hougen, Jon T.

2015-01-01

A new hybrid-model fitting program for methylamine-like molecules has been developed, based on an effective Hamiltonian in which the ammonia-like inversion motion is treated using a tunneling formalism, while the internal-rotation motion is treated using an explicit kinetic energy operator and potential energy function. The Hamiltonian in the computer program is set up as a 2×2 partitioned matrix, where each diagonal block contains a traditional torsion-rotation Hamiltonian (as in the earlier program BELGI), and the two off-diagonal blocks contain tunneling terms. This hybrid formulation permits the use of the permutation-inversion group G6 (isomorphic to C3v) for terms in the two diagonal blocks, but requires G12 for terms in the off-diagonal blocks. The first application of the new program is to 2-methylmalonaldehyde. Microwave data for this molecule were previously fit using an all-tunneling Hamiltonian formalism to treat both large-amplitude-motions. For 2-methylmalonaldehyde, the hybrid program achieves the same quality of fit as was obtained with the all-tunneling program, but fits with the hybrid program eliminate a large discrepancy between internal rotation barriers in the OH and OD isotopologs of 2-methylmalonaldehyde that arose in fits with the all-tunneling program. This large isotopic shift in internal rotation barrier is thus almost certainly an artifact of the all-tunneling model. Other molecules for application of the hybrid program are mentioned. PMID:26439709

The Doctor of Medicine curriculum review at the School of Medicine, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania: a tracer study report from 2009.

PubMed

Mwakigonja, Amos Rodger

2016-08-25

The School of Medicine (SoM) is one among five at Muhimbili University of Health and Allied Sciences (MUHAS). It currently houses eight undergraduate and many post-graduate programmes. The Doctor of Medicine (MD) programme reported herein is the oldest having ten semesters (5 years) followed by a 1 year compulsory rotatory internship at a hospital approved by the Medical Council of Tanganyika (MCT). However, this training was largely knowledge-based and thus the need to shift towards competency-based education (CBE) and full modularization necessitated this study. A cross-sectional tracer study of MUHAS MD graduates from SoM who completed training between 2006 and 2008 was conducted using quantitative (structured interviewer-administered questionnaires) as well as qualitative methods [In-depth questionnaire (IDI) and Focus group discussions (FGDs)]. A total of 147 MD graduates were traced and interviewed, representing 29 % of the 510 students who graduated from the SoM between 2006 and 2008. Majority (70.1 %, n = 103/147) were males. About 70 % graduated in 2008 and majority (68 %, n = 100/147) were doing internship. Majority (60.5 % n = 89/147) were based in/near Dar es Salaam at district, regional or referral hospitals. With reasonable concordance, most competencies ranked low except on four aspects. Teaching, System-based Practice and Good Practice had the lowest. Seminars/Tutorials, Laboratory Skills/Practicals, Theatre Skills, Outpatients clinics, Family Case Studies, Visits/Excursions and Self Reflection were rated less useful teaching methods compared to Lectures, Teaching Ward Rounds, Elective Studies, Field Work, Presentations, Continuous Assessments Tests, Final Examinations, Short Answers, Clinical/Practical Examinations. ICT and Library facilities were not considered to meet the students learning needs and Clinical Logbooks also ranked low. Teachers were generally ranked less favorably including in professional role-modelling and accessibility outside scheduled teaching sessions. This tracer study results allowed subsequent curriculum review and the introduction of full modularization and competency-based learning at MUHAS. It is envisioned that these tracer study findings will improve teaching, learning and inform next curriculum review at MUHAS leading to increased output of appropriately trained health professionals to fill the big gap in human resources for health (HRH) in Tanzania. The revised curricula are also being processed through TCU for accreditation as required.

The impact of diurnal sleep on the consolidation of a complex gross motor adaptation task

PubMed Central

Hoedlmoser, Kerstin; Birklbauer, Juergen; Schabus, Manuel; Eibenberger, Patrick; Rigler, Sandra; Mueller, Erich

2015-01-01

Diurnal sleep effects on consolidation of a complex, ecological valid gross motor adaptation task were examined using a bicycle with an inverse steering device. We tested 24 male subjects aged between 20 and 29 years using a between-subjects design. Participants were trained to adapt to the inverse steering bicycle during 45 min. Performance was tested before (TEST1) and after (TEST2) training, as well as after a 2 h retention interval (TEST3). During retention, participants either slept or remained awake. To assess gross motor performance, subjects had to ride the inverse steering bicycle 3 × 30 m straight-line and 3 × 30 m through a slalom. Beyond riding time, we sophisticatedly measured performance accuracy (standard deviation of steering angle) in both conditions using a rotatory potentiometer. A significant decrease of accuracy during straight-line riding after nap and wakefulness was shown. Accuracy during slalom riding remained stable after wakefulness but was reduced after sleep. We found that the duration of rapid eye movement sleep as well as sleep spindle activity are negatively related with gross motor performance changes over sleep. Together these findings suggest that the consolidation of adaptation to a new steering device does not benefit from a 2 h midday nap. We speculate that in case of strongly overlearned motor patterns such as normal cycling, diurnal sleep spindles and rapid eye movement sleep might even help to protect everyday needed skills, and to rapidly forget newly acquired, interfering and irrelevant material. PMID:25256866

The Crystal Structure of Oxaliplatin: A Case of Overlooked Pseudo Symmetry.

PubMed

Johnstone, Timothy C

2014-01-08

The crystal structure of the anticancer drug oxaliplatin, [Pt( R,R- DACH)(oxalate)] (DACH = diaminocyclohexane), was first reported in the non-centrosymmetric space group P2 1 , confirming the sole presence of the R , R enantiomer of the DACH ligand [M. A. Bruck et al. , Inorg. Chim. Acta , 92 (1984) 279-284]. It was later proposed that the crystal structure is better described in the centrosymmetric space group P2 1 /m, signifying the presence of the compound as a racemic mixture [A. S. Abu-Surrah et al. , Polyhedron , 22 (2003) 1529-1534]. Herein is presented a reinvestigation of this crystal structure, which shows that the discrepancy between the two proposed space group assignments arises from overlooked pseudo symmetry. The crystal structures of the synthetic precursor to oxaliplatin, Pt( R , R -DACH)I 2 , and a platinum(IV) derivative, trans -[Pt( R , R -DACH)(oxalate)(OH) 2 ], were also determined, and the absolute configuration of the DACH ligand in each was confirmed to be R , R . A spectroscopic investigation of the optical rotatory dispersion (ORD) of the oxaliplatin crystals was carried out to further confirm the lack of the true crystallographic mirror plane required for a P2 1 /m solution. The ORD was theoretically simulated, in one instance, by applying the Kramers-Kronig transform to the computed circular dichroism spectrum and was found to corroborate the spectroscopic and crystallographic findings. Finally, a brief discussion is given of the importance of discussing the details of nuanced crystal structures and of providing evidence in addition to X-ray structure determination if chemically unexpected results are obtained.

The Crystal Structure of Oxaliplatin: A Case of Overlooked Pseudo Symmetry

PubMed Central

Johnstone, Timothy C.

2013-01-01

The crystal structure of the anticancer drug oxaliplatin, [Pt(R,R-DACH)(oxalate)] (DACH = diaminocyclohexane), was first reported in the non-centrosymmetric space group P21, confirming the sole presence of the R,R enantiomer of the DACH ligand [M. A. Bruck et al., Inorg. Chim. Acta, 92 (1984) 279–284]. It was later proposed that the crystal structure is better described in the centrosymmetric space group P21/m, signifying the presence of the compound as a racemic mixture [A. S. Abu-Surrah et al., Polyhedron, 22 (2003) 1529–1534]. Herein is presented a reinvestigation of this crystal structure, which shows that the discrepancy between the two proposed space group assignments arises from overlooked pseudo symmetry. The crystal structures of the synthetic precursor to oxaliplatin, Pt(R,R-DACH)I2, and a platinum(IV) derivative, trans-[Pt(R,R-DACH)(oxalate)(OH)2], were also determined, and the absolute configuration of the DACH ligand in each was confirmed to be R,R. A spectroscopic investigation of the optical rotatory dispersion (ORD) of the oxaliplatin crystals was carried out to further confirm the lack of the true crystallographic mirror plane required for a P21/m solution. The ORD was theoretically simulated, in one instance, by applying the Kramers-Kronig transform to the computed circular dichroism spectrum and was found to corroborate the spectroscopic and crystallographic findings. Finally, a brief discussion is given of the importance of discussing the details of nuanced crystal structures and of providing evidence in addition to X-ray structure determination if chemically unexpected results are obtained. PMID:24415827

The preclinical sheep model of high tibial osteotomy relating basic science to the clinics: standards, techniques and pitfalls.

PubMed

Pape, Dietrich; Madry, Henning

2013-01-01

To develop a preclinical large animal model of high tibial osteotomy to study the effect of axial alignment on the lower extremity on specific issues of the knee joint, such as in articular cartilage repair, development of osteoarthritis and meniscal lesions. Preoperative planning, surgical procedure and postoperative care known from humans were adapted to develop a HTO model in the adult sheep. Thirty-five healthy, skeletally mature, female Merino sheep between 2 and 4 years of age underwent a HTO of their right tibia in a medial open-wedge technique inducing a normal (group 1) and an excessive valgus alignment (group 2) and a closed-wedge technique (group 3) inducing a varus alignment with the aim of elucidating the effect of limb alignment on cartilage repair in vivo. Animals were followed up for 6 months. Solid bone healing and maintenance of correction are most likely if the following surgical principles are respected: (1) medial and longitudinal approach to the proximal tibia; (2) biplanar osteotomy to increase initial rotatory stability regardless of the direction of correction; (3) small, narrow but long implant with locking screws; (4) posterior plate placement to avoid slope changes; (5) use of bicortical screws to account for the brittle bone of the tibial head and to avoid tibial head displacement. Although successful high tibial osteotomy in sheep is complex, the sheep may--because of its similarities with humans--serve as an elegant model to induce axial malalignment in a clinically relevant environment, and osteotomy healing under challenging mechanical conditions.

[Isolation of wood-decaying fungi and evaluation of their enzymatic activity (Quindío, Colombia)].

PubMed

Chaparro, Deisy Fernanda; Rosas, Diana Carolina; Varela, Amanda

2009-12-31

White rot fungi (Ascomycota and Basidiomycota) were collected on fallen trunks with different decay stages, in a subandean forest (La Montaña del Ocaso nature reserve), and it was evaluated their ligninolitic activity. They were cultured on malt extract agar. Then it was performed semiquantitative tests for laccase and cellobiose dehydrogenase (CDH) activity using ABTS and DCPIP as enzymatic inducers. Based on the results of these tests, the fungi with higher activities from trunks with different decay stages were selected: Cookeina sulcipes (for stage 1), a fungus from the family Corticiaceae (for stage 2), Xylaria polymorpha (for stage 3) and Earliella sp. (for stage 4). A fermentation was performed at 28 degrees C, during 11 days, in a rotatory shaker at 150 rpm. Biomass, glucose, proteins and enzyme activities measurements were performed daily. The fungi that were in the trunks with decay states from 1 to 3, showed higher laccase activity as the state of decay increased. A higher DCH activity was also associated with a higher. Also, there was a positive relationship between both enzymes' activities. Erliella was the fungus which presented the highest biomass production (1140,19 g/l), laccase activity (157 UL(-1)) and CDH activity (43,50 UL(-1)). This work is the first report of laccase and CDH activity for Cookeina sulcipes and Earliella sp. Moreover, it gives basis for the use of these native fungi in biotechnological applications and the acknowledgment of their function in the wood decay process in native forest.

Third order nonlinear optical properties of a paratellurite single crystal

NASA Astrophysics Data System (ADS)

Duclère, J.-R.; Hayakawa, T.; Roginskii, E. M.; Smirnov, M. B.; Mirgorodsky, A.; Couderc, V.; Masson, O.; Colas, M.; Noguera, O.; Rodriguez, V.; Thomas, P.

2018-05-01

The (a,b) plane angular dependence of the third-order nonlinear optical susceptibility, χ(3) , of a c-cut paratellurite (α-TeO2) single crystal was quantitatively evaluated here by the Z-scan technique, using a Ti:sapphire femtosecond laser operated at 800 nm. In particular, the mean value Re( ⟨χ(3)⟩a,b )(α-TeO2) of the optical tensor has been extracted from such experiments via a direct comparison with the data collected for a fused silica reference glass plate. A R e (⟨χ(3)⟩(a,b )(α-TeO2)):R e (χ(3))(SiO2 glass) ratio roughly equal to 49.1 is found, and our result compares thus very favourably with the unique experimental value (a ratio of ˜50) reported by Kim et al. [J. Am. Ceram. Soc. 76, 2486 (1993)] for a pure TeO2 glass. In addition, it is shown that the angular dependence of the phase modulation within the (a,b) plane can be fully understood in the light of the strong dextro-rotatory power known for TeO2 materials. Taking into account the optical activity, some analytical model serving to estimate the diagonal and non-diagonal components of the third order nonlinear susceptibility tensor has been thus developed. Finally, Re( χxxxx(3) ) and Re( χxxyy(3) ) values of 95.1 ×10-22 m 2/V2 and 42.0 ×10-22 m2/V2 , respectively, are then deduced for a paratellurite single crystal, considering fused silica as a reference.

Solid state radiolysis of amino acids in an astrochemical perspective

NASA Astrophysics Data System (ADS)

Cataldo, Franco; Angelini, Giancarlo; Iglesias-Groth, Susana; Manchado, Arturo

2011-01-01

The aliphatic amino acids L-alanine and L-leucine and the aromatic amino acids L-phenylalanine, L-tyrosine and L-tryptophan were irradiated in the solid state to a dose of 3.2 MGy. The degree of decomposition was measured by differential scanning calorimetry (DSC). Furthermore the degree of radioracemization was measured by optical rotatory dispersion (ORD) spectroscopy. From the DSC measurement a radiolysis rate constant k and the half life T1/2 for each amino acid have been determined and extrapolated to a dose of 14 MGy, which corresponds to the expected total dose delivered by the decay of radionuclides to the organic molecules present in comets and asteroids in 4.6×109 years, the age of the Solar System. It is shown that all the amino acids studied can survive a radiation dose of 14 MGy although they are reduced to 1/4-1/5 of their original value they had at the beginning of the history of the Solar System. Consequently, the amount of alanine or leucine found today in the meteorites known as carbonaceous chondrites is just 1/4-1/5 of the amount originally present at the epoch of the formation of the Solar System 4.6×109 years ago. Among the amino acids studied, tyrosine shows the highest radiation resistance while tryptophan does not combine its relatively high radiation resistance with an elevated level of radioracemization resistance. Apart from the exception of tryptophan, it is shown that the radiolysis rate constants k of all the amino acids studied are in reasonable agreement with the radioracemization rate constant krac.

Oculopalatal tremor, facial myokymia and truncal ataxia in a patient with neurosarcoidosis.

PubMed

Sidiropoulos, Christos; Sripathi, Naganand; Nasrallah, Khalil; Mitsias, Panayiotis

2014-12-01

Symptomatic palatal tremor (SPT) is the result of a structural lesion, in the form of stroke, trauma or demyelinating disease. SPT is due to contractions of the levator veli palatini and can be accompanied by simultaneous movements of the facial and ocular muscles. Facial myokymia (FM) is a persistent quivering of the facial muscles. FM is usually encountered with conditions involving the pontine tegmentum. We report, to our knowledge, the first patient with neurosarcoidosis with simultaneous SPT and FM. A 49-year-old African American woman, with non-caseating granulomas in a paratracheal lymph node biopsy, presented with progressive gait disturbances for the last 3 years. Neurological examination revealed ataxic speech, bilateral rotatory nystagmus, myokymia of the chin and perioral muscles, palatal tremor without ear click and marked truncal ataxia. MRI demonstrated a lesion involving the facial nucleus and the right middle cerebellar peduncle. Based on exclusion of alternative etiologies, a diagnosis of neurosarcoidosis was made and the patient was started on methotrexate for 9 months, with minimal improvement. She was then switched to intravenous infliximab without major adverse events. The patient's speech and gait ataxia improved and follow up MRI demonstrated resolution of the enhancing lesions. To our knowledge, this is the first reported case of the combination of palatal tremor and FM due to neurosarcoidosis. Methotrexate may fail to produce clinical or radiographic response in up to 39% of patients. Tumor necrosis factor-α inhibitors, such as infliximab, should be considered in refractory cases. Copyright © 2014 Elsevier Ltd. All rights reserved.

Exploratory factor analysis of the functional movement screen in elite athletes.

PubMed

Li, Yongming; Wang, Xiong; Chen, Xiaoping; Dai, Boyi

2015-01-01

The functional movement screen is developed to examine individuals' movement patterns through 7 functional tasks. The purpose of this study was to identify the internal consistency and factor structure of the 7 tasks of the functional movement screen in elite athletes; 290 elite athletes from a variety of Chinese national teams were assessed using the functional movement screen. Cronbach's alpha was calculated for the scores of the 7 tasks. Exploratory factor analysis was performed to explore the factor structure of the functional movement screen. The mean and standard deviation of the sum score were 15.2 ± 3.0. A low Cronbach's alpha (0.58) was found for the scores of the 7 tasks. Exploratory factor analysis extracted 2 factors with eigenvalues greater than 1, and these 2 factors explained 47.3% of the total variance. The first factor had a high loading on the rotatory stability (loading = 0.99) and low loadings on the other 6 tasks (loading range: 0.04-0.34). The second factor had high loadings on the deep squat, hurdle step and inline lunge (loading range: 0.46-0.61) and low loadings on the other 3 tasks (loading range: 0.12-0.32). The 7 tasks of the functional movement screen had low internal consistency and were not indicators of a single factor. Evidence for unidimensionality was not found for the functional movement screen in elite athletes. More attention should be paid to the score of each task rather than the sum score when we interpret the functional movement screen scores.

Anomaly-Related Pathologic Atlantoaxial Displacement in Pediatric Patients.

PubMed

Pavlova, Olga M; Ryabykh, Sergey O; Burcev, Alexander V; Gubin, Alexander V

2018-06-01

To analyze clinical and radiologic features of pathologic atlantoaxial displacement (PAAD) in pediatric patients and to compose a treatment algorithm for anomaly-related PAAD. Criteria of different types of PAAD and treatment algorithms have been widely reported in the literature but are difficult to apply to patients with odontoid abnormalities, C2-C3 block, spina bifida C1, and children. We evaluated results of treatment of 29 pediatric patients with PAAD caused by congenital anomalies of the craniovertebral junction (CVJ), treated in Ilizarov Center in 2009-2017, including 20 patients with atlantoaxial displacement (AAD) and 9 patients with atlantoaxial rotatory fixation. There were 14 males (48.3%) and 15 females (51.7%). We singled out 3 groups of patients: nonsyndromic (6 patients, 20.7%), Klippel-Feil syndrome (13 patients, 44.8%), and syndromic (10 patients, 34.5%). Odontoid abnormalities and C1 dysplasia were widely represented in the syndromic group. Local symptoms predominated in the nonsyndromic and KFS groups. In the syndromic group, all patients had AAD and myelopathy. A pronounced decrease of space available for chord C1 and increase of anterior atlantodental interval were noted compared with other groups. We present a unified treatment algorithm of pediatric anomaly-related PAAD. Syndromic AAD are often accompanied by anterior and central dislocation and myelopathy and atlantooccipital dissociation. These patients require early aggressive surgical treatment. Nonsyndromic and Klippel-Feil syndrome AAD, atlantoaxial subluxation, and atlantoaxial fixation often manifest by local symptoms and need to eliminate CVJ instability. Existing classifications of symptomatic atlantoaxial displacement are not always suitable for patients with CVJ abnormalities. Copyright © 2018 Elsevier Inc. All rights reserved.

Anti-ulcerogenic effect of the methanol extract of Chasmanthera dependens (Hochst) stem on male Wistar rats.

PubMed

Tijani, Stephanie Abiola; Olaleye, Samuel B; Farombi, Ebenezer O

2018-04-19

Oxidative stress and free radical-mediated processes have been implicated in the pathogenesis of indomethacin-induced gastric ulcer. This study investigated the ability of the methanol extract of Chasmanthera dependens to protect the gastric mucosal from oxidative damage induced by oral administration of indomethacin in rats. The C. dependens stems were chopped into pieces, air-dried, and pulverized into powder. One kilogram of the powder was macerated in 1 L of methanol for 72 h. The mixture was filtered and evaporated using rotatory evaporator to obtain the extract of C. dependens. Adult male rats were divided into eight groups of six animals per group and were pretreated orally with the methanol extract of C. dependens (200, 400, and 800 mg/kg) or cimetidine (CIM), a standard drug (50 mg/kg), for 7 days. Gastric ulcer was induced orally with indomethacin. Ulcerogenic parameters, oxidative stress indices, and histopathological examination of the stomach were assessed to monitor the gastroprotective potential of C. dependens stem. Indomethacin caused severe gastric mucosa damage and significant reduction in the gastric mucosa antioxidant system with concomitant increase in the level of lipid peroxidation. Pretreatment with the methanol extract of C. dependens or CIM significantly reduced the formation of ulcer at the different doses administered. Similarly, pretreatments with the extract or CIM improved the antioxidant system, decreased acid output, lipid peroxidation, and improved the architecture of the gastric mucosa in ulcerated rats. The results show the gastroprotective effect of the methanolic extract of C. dependens, which may be attributed to its antioxidant properties.

Cancer-adipose tissue interaction and fluid flow synergistically modulate cell kinetics, HER2 expression, and trastuzumab efficacy in gastric cancer.

PubMed

Akutagawa, Takashi; Aoki, Shigehisa; Yamamoto-Rikitake, Mihoko; Iwakiri, Ryuichi; Fujimoto, Kazuma; Toda, Shuji

2018-04-25

Early local tumor invasion in gastric cancer results in likely encounters between cancer cells and submucosal and subserosal adipose tissue, but these interactions remain to be clarified. Microenvironmental mechanical forces, such as fluid flow, are known to modulate normal cell kinetics, but the effects of fluid flow on gastric cancer cells are poorly understood. We analyzed the cell kinetics and chemosensitivity in gastric cancer using a simple in vitro model that simultaneously replicated the cancer-adipocyte interaction and physical microenvironment. Gastric cancer cells (MKN7 and MKN74) were seeded on rat adipose tissue fragment-embedded discs or collagen discs alone. To generate fluid flow, samples were placed on a rotatory shaker in a CO 2 incubator. Proliferation, apoptosis, invasion, and motility-related molecules were analyzed by morphometry and immunostaining. Proteins were evaluated by western blot analysis. Chemosensitivity was investigated by trastuzumab treatment. Adipose tissue and fluid flow had a positive synergistic effect on the proliferative potential and invasive capacity of gastric cancer cells, and adipose tissue inhibited apoptosis in these cells. Adipose tissue upregulated ERK1/2 signaling in gastric cancer cells, but downregulated p38 signaling. Notably, adipose tissue and fluid flow promoted membranous and cytoplasmic HER2 expression and modulated chemosensitivity to trastuzumab in gastric cancer cells. We have demonstrated that cancer-adipocyte interaction and physical microenvironment mutually modulate gastric cancer cell kinetics. Further elucidation of the microenvironmental regulation in gastric cancer will be very important for the development of strategies involving molecular targeted therapy.

ACL Fibers Near the Lateral Intercondylar Ridge Are the Most Load Bearing During Stability Examinations and Isometric Through Passive Flexion.

PubMed

Nawabi, Danyal H; Tucker, Scott; Schafer, Kevin A; Zuiderbaan, Hendrik Aernout; Nguyen, Joseph T; Wickiewicz, Thomas L; Imhauser, Carl W; Pearle, Andrew D

2016-10-01

The femoral insertion of the anterior cruciate ligament (ACL) has direct and indirect fiber types located within the respective high (anterior) and low (posterior) regions of the femoral footprint. The fibers in the high region of the ACL footprint carry more force and are more isometric than the fibers in the low region of the ACL footprint. Controlled laboratory study. Ten fresh-frozen cadaveric knees were mounted to a robotic manipulator. A 134-N anterior force at 30° and 90° of flexion and combined valgus (8 N·m) and internal (4 N·m) rotation torques at 15° of flexion were applied simulating tests of anterior and rotatory stability. The ACL was sectioned at the femoral footprint by detaching either the higher band of fibers neighboring the lateral intercondylar ridge in the region of the direct insertion or the posterior, crescent-shaped fibers in the region of the indirect insertion, followed by the remainder of the ACL. The kinematics of the ACL-intact knee was replayed, and the reduction in force due to each sectioned portion of insertion fibers was measured. Isometry was assessed at anteromedial, center, and posterolateral locations within the high and low regions of the femoral footprint. With an anterior tibial force at 30° of flexion, the high fibers carried 83.9% of the total anterior ACL load compared with 16.1% in the low fibers (P < .001). The high fibers also carried more anterior force than the low fibers at 90° of flexion (95.2% vs 4.8%; P < .001). Under combined torques at 15° of flexion, the high fibers carried 84.2% of the anterior ACL force compared with 15.8% in the low fibers (P < .001). Virtual ACL fibers placed at the anteromedial portion of the high region of the femoral footprint were the most isometric, with a maximum length change of 3.9 ± 1.5 mm. ACL fibers located high within the femoral footprint bear more force during stability testing and are more isometric during flexion than low fibers. It may be advantageous to create a "higher" femoral tunnel during ACL reconstruction at the lateral intercondylar ridge. © 2016 The Author(s).

Extra-articular tenodesis combined with an anterior cruciate ligament reconstruction in acute anterior cruciate ligament tear in elite female football players.

PubMed

Guzzini, Matteo; Mazza, Daniele; Fabbri, Mattia; Lanzetti, Riccardo; Redler, Andrea; Iorio, Carlo; Monaco, Edoardo; Ferretti, Andrea

2016-10-01

The growing popularity of elite soccer among female participants has led to increased incidents of anterior cruciate ligament (ACL) ruptures. Many authors underline a positive glide after ACL reconstruction (ACLR), especially in women. In fact, an isolated intra-articular ACLR may be inadequate to control rotational instability after a combined injury of the ACL and the peripheral structures of the knee. Extra-articular procedures are sometimes used in primary cases displaying excessive antero-lateral rotatory instability. The purpose of this case series was to report subjective and objective outcomes after combined ACL and lateral extra-articular tenodesis (LET) with a minimum 4-year follow-up in a selected high-risk population of elite female football players. Between January 2007 and December 2010, 16 elite Italian female football players were included in the study. All patients underwent the same surgical technique: anatomical ACLR with autogenous semitendinosus and gracilis tendons. After the intra-articular reconstruction was performed, an additional extra-articular MacIntosh modified Coker-Arnold procedure was carried out. Patients were assessed pre- and post-operatively with the subjective and objective International Knee Documentation Committee (IKDC) evaluation form, Tegner activity scale (TAS) and Lysholm score. Joint laxity was assessed with KT-1000 by measuring the side-to-side (S/S) differences in displacement at manual maximum (mm) testing. At a mean follow-up of 72.6 ± 8.1 months, two independent examiners reviewed all players. All of the patients had a fully recovered range of motion. Lachman test was negative in all patients (100 %). The evaluation of joint laxity and clinical evaluation showed a statistically significant improvement. No patients experienced complication or a re-rupture. The rationale of combining extra-articular procedures with ACLR is to restrict the internal rotation of the reconstructed knee, taking advantage of its long lever arm and thus providing more stability in the rotational axis and preventing the ACL graft from undergoing further excessive strain. The combination of an LET with ACLR in elite female football players demonstrated excellent results in terms of subjective scales, post-operative residual laxity and re-rupture rate with no complication, and a complete return to sport activity.

Global rotation has high sensitivity in ACL lesions within stress MRI.

PubMed

Espregueira-Mendes, João; Andrade, Renato; Leal, Ana; Pereira, Hélder; Skaf, Abdala; Rodrigues-Gomes, Sérgio; Oliveira, J Miguel; Reis, Rui L; Pereira, Rogério

2017-10-01

This study aims to objectively compare side-to-side differences of P-A laxity alone and coupled with rotatory laxity within magnetic resonance imaging, in patients with total anterior cruciate ligament (ACL) rupture. This prospective study enrolled sixty-one patients with signs and symptoms of unilateral total anterior cruciate ligament rupture, which were referred to magnetic resonance evaluation with simultaneous instrumented laxity measurements. Sixteen of those patients were randomly selected to also have the contralateral healthy knee laxity profile tested. Images were acquired for the medial and lateral tibial plateaus without pressure, with postero-anterior translation, and postero-anterior translation coupled with maximum internal and external rotation, respectively. All parameters measured were significantly different between healthy and injured knees (P < 0.05), with exception of lateral plateau without stress. The difference between injured and healthy knees for medial and lateral tibial plateaus anterior displacement (P < 0.05) and rotation (P < 0.001) was statistically significant. It was found a significant correlation between the global rotation of the lateral tibial plateau (lateral plateau with internal + external rotation) with pivot-shift, and between the anterior global translation of both tibial plateaus (medial + lateral tibial plateau) with Lachman. The anterior global translation of both tibial plateaus was the most specific test with a cut-off point of 11.1 mm (93.8 %), and the global rotation of the lateral tibial plateau was the most sensitive test with a correspondent cut-off point of 15.1 mm (92.9 %). Objective laxity quantification of ACL-injured knees showed increased sagittal laxity, and simultaneously in sagittal and transversal planes, when compared to their healthy contralateral knee. Moreover, when measuring instability from anterior cruciate ligament ruptures, the anterior global translation of both tibial plateaus and global rotation of the lateral tibial plateau add diagnostic specificity and sensitivity. This work strengthens the evidence that the anterior cruciate ligament plays an important biomechanical role in controlling the anterior translation, but also both internal and external rotation. The high sensitivity and specificity of this device in objectively identifying and measuring the multiplanar instability clearly guides stability restoration clinical procedures. Level of evidence Cross-sectional study, Level III.

[The effect of instrumentation on original apical foramen shape using steel vs niti rotatory: computerized analysis].

PubMed

Gallina, G; Cumbo, E; Gallo, P; Pizzo, G; D'Angelo, M

2002-01-01

A fundamental requirement to obtain a correct endodontic preparation depends on the respect, during cleaning and shaping, of the original morphology of the apical foramen, (AF), so that the filling material will form a complete seal. In our previous studies, in order to verify if this presumption was respected using rotary NiTi instruments with cutting tip, we instrumented extracted teeth characterised by a different degree of root curvatures. Using a standardized system to replace the sample, the original shape of the apical foramen of each tooth was recorded using a computerised technique and then compared to the shape after instrumentation. The data showed differences on AF shapes depending on the degree of root canal curvatures. In fact, the teeth with straight canals showed the least alterations on the original AF shape; on the contrary, the teeth with curved canals showed apical foramen enlargement or transportation. Therefore, in the current study we aimed to compare the in vitro effects of stainless steel, (Flexofile, Dentsply Maillefer, Baillaigues, Switzerland), vs NiTi safe cutting tip (Quantec SC, (Tycom Dental, Irvine CA, U:S.A.), vs NiTi non cutting tip, (Quantec LX, Tycom Dental, Irvine CA, U:S.A.), instrumentation on original apical foramen shape. We used NiTi instruments according to standard technique suggested by Tycom, and hand steel files, to instrument the apical third, according to the Crown-Down technique. Working length was fixed at -0.5 from AF. Our results suggested that in the presence of accentuated canal curves rotary Niti, with cutting tip, cause significantly more enlargement of the AF area. At the same time, we also observed that NiTi rotary files, with both cutting and non-cutting tip, cause eccentric enlargement of AF in curved canals. Therefore, NiTi engine-driven instruments should be used carefully in the presence of accentuated canal curves to avoid enlargement or transportation of AF, probably because rotary NiTi files may slip out of operative control, leaving a mark on the foramen shape. In the presence of severe curves, we suggest modifying the operative sequences by alternating rotary NiTi with hand NiTi or stainless steel instruments, especially in the preparation of apical third.

Experiments of the origins of optical activity.

PubMed

Bonner, W A; Flores, J J

1975-01-01

Two recent reports claim that (1) aqueous L-aspartic acid polymerizes faster than D-Asp in the presence of kaolin at 90 degrees, and (2) L-phenylalanine is adsorbed by kaolin more extensively than D-Phe at pH 4(the reverse being true at pH2). The novelty of these observations and their potential significance for the origin of optical activity has prompted us to duplicate these experiments using more sensitive methods. L- and D, L-Asp in 0.01 M solution were incubated with kaolin at 90 degrees for 8 days. Careful examination of the aqueous residues from such experiments failed to demonstrate any preferential polymerization of L-Asp over D-Asp, or indeed any significant gross polymerization of Asp at all. In other experiments 0.001 M solutions of D, L-Phe at pH 6 and pH 2 were stirred with large excesses of kaolin for 24 hr, and the aqueous extracts from these mixtures were examined for gross adsorption using the amino acid analyzer. No significant gross adsorption was noted. We then looked for asymmetric adsorption in the aqueous residues using optical rotatory dispersion, gas chromatography and thin layer chromatography. By none of these analytical criteria could we find any evidence whatsoever for the preferential adsorption of D- versus L-Phe from either pH 6 or pH 2 solutions. Finally, in experiments bearing on the origin of optical activity by parity violation during beta-decay, we have irradiated solid samples of D-, L- and D,L-leucine in a 61700 Ci Sr-90 source at Oak Ridge National Lab. for 1.34 yr (total dose: 4.2 x 10(8) rad). Gas chromatographic examination of the (appropriately derivitized) recovered samples showed that the L-Leu was 16.7% decomposed, the D-Leu 11.4% and theD,L-Leu 13.8% decomposed. The recovered D,L-Leu sample had a gas-chromatographically determined enantiomeric composition of 50.8% D-leu and 49.2% L-Leu. These data, though very close to experimental error, may indicate a slight preferential radiolysis of L-Leu compared to D-Leu by the Bremsstrahlung from Sr-90 beta-decay. These high intensity irradiation experiments are being continued on a prolonged basis in order to reach more definitive conclusions.

Outcomes of coronoid-first repair in terrible triad injuries of the elbow.

PubMed

Zhang, Junren; Tan, Mark; Kwek, Ernest Beng Kee

2017-09-01

Clinical outcomes of terrible triad injuries (TTIs) of the elbow are historically poor. To date, it is still debatable whether the coronoid needs to be fixed and if so, how and in which sequence. Between 2010 and 2013, 13 patients were treated surgically for acute TTIs of the elbow at a Tertiary Level 1 Trauma Centre by a single surgeon, using a standardized protocol, which included coronoid-brachialis complex fixation via pull-through trans-osseous sutures, radial head fixation or prosthetic replacement and a repair of the lateral ulnar collateral ligament. Repair of the medial collateral ligament (MCL) was done if valgus-stress test demonstrated persistent instability. Patients were then followed-up with clinical and radiological evaluation by the senior author until fracture union and elbow range of motion reached a plateau. Outcomes measured were range of motion, DASH scores and MEPS, as well as surgical complications. Intraoperative stability was achieved in all 13 cases, MCL repair was required in 3 cases and application of external fixation was not required in any case. Patients were followed-up for an average length of 27.7 months and the minimum follow-up period was 12 months. The average age of patients was 46.4 years (range 35-79 years old) at the time of trauma. This included eight Regan-Morrey Type I and five Regan-Morrey Type II coronoid fractures, with ten Mason Type I/II and three Mason Type III radial head fractures. The average arc of ulno-humeral motion was 105.0° (range 80°-135°). The average flexion contracture was 15.0° (range 0°-40°). The average supination-pronation arc was 114.9° (range 0°-180°). The average MEPS was 85 of 100 (range 45-100) and the average DASH score was 21.2 of 100 (range 1.7-61.2). A single case of radio-ulnar synostosis, heterotropic ossification and two cases of recurrent elbow instability were noted. The coronoid-first surgical approach, using a suture-lasso fixation method, has technical benefits for us and showed good clinical success in our series. This is important with postero-medial rotatory instability being common in our series of TTIs. We emphasize not to miss a TTI in an apparently isolated low Mason class radial head fracture.

The impact of diurnal sleep on the consolidation of a complex gross motor adaptation task.

PubMed

Hoedlmoser, Kerstin; Birklbauer, Juergen; Schabus, Manuel; Eibenberger, Patrick; Rigler, Sandra; Mueller, Erich

2015-02-01

Diurnal sleep effects on consolidation of a complex, ecological valid gross motor adaptation task were examined using a bicycle with an inverse steering device. We tested 24 male subjects aged between 20 and 29 years using a between-subjects design. Participants were trained to adapt to the inverse steering bicycle during 45 min. Performance was tested before (TEST1) and after (TEST2) training, as well as after a 2 h retention interval (TEST3). During retention, participants either slept or remained awake. To assess gross motor performance, subjects had to ride the inverse steering bicycle 3 × 30 m straight-line and 3 × 30 m through a slalom. Beyond riding time, we sophisticatedly measured performance accuracy (standard deviation of steering angle) in both conditions using a rotatory potentiometer. A significant decrease of accuracy during straight-line riding after nap and wakefulness was shown. Accuracy during slalom riding remained stable after wakefulness but was reduced after sleep. We found that the duration of rapid eye movement sleep as well as sleep spindle activity are negatively related with gross motor performance changes over sleep. Together these findings suggest that the consolidation of adaptation to a new steering device does not benefit from a 2 h midday nap. We speculate that in case of strongly overlearned motor patterns such as normal cycling, diurnal sleep spindles and rapid eye movement sleep might even help to protect everyday needed skills, and to rapidly forget newly acquired, interfering and irrelevant material. © 2014 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.

Ultrasound analysis of the vertebral artery during non-thrust cervical translatoric spinal manipulation.

PubMed

Creighton, Doug; Kondratek, Melodie; Krauss, John; Huijbregts, Peter; Qu, Harvey

2011-05-01

Cervical translatoric spinal manipulation (TSM) techniques have been suggested as a safer alternative to cervical thrust rotatory techniques. The objective of this study was to determine the effect of three C5-C6 non-thrust TSM techniques on vertebral artery (VA) lumen diameter (LD) and two blood flow velocity parameters. The two-tailed research hypothesis was that the TSM techniques would result in a significant change (increase or decrease) in blood flow velocity and arterial LD at the C5-C6 intertransverse portion of the VA. In a sample of 30 subjects representative of a clinical population, color-coded duplex Doppler diagnostic ultrasound imaging was used to collect data on LD, peak systolic velocity (PSV), and end diastolic velocity with the cervical spine positioned in neutral and in three different manipulation positions. Pair-wise mean differences between measurements at baseline (neutral position) and in all three manipulation positions were analyzed using two-tailed paired t-tests with alpha set at 0·05. Of the 18 paired comparisons, there were four statistically significant differences between measurements in the neutral position and a manipulation position, three concerning LD and one PSV. The three significant differences in LD ranged from 4·6 to 3·2% and were not associated with changes in blood flow velocity. The one significant change in PSV was only 6·6 cm/s. A value that still greatly exceeded the end diastolic velocity. No subject experienced symptoms associated with VA compromise. This study has provided evidence for the safety of the three lower cervical non-thrust TSM techniques on the current population studied. Further study is required on thrust versus non-thrust TSM techniques and on levels other than C5-C6.

Studies of the Interactions Between Vestibular Function and Tactual Orientation Display Systems

NASA Technical Reports Server (NTRS)

Cholewiak, Roger W.; Reschke, Millard F.

1997-01-01

When humans experience conditions in which internal vestibular cues to movement or spatial location are challenged or contradicted by external visual information, the result can be spatial disorientation, often leading to motion sickness. Spatial disorientation can occur in any situation in which the individual is passively moved in the environment, but is most common in automotive, aircraft, or undersea travel. Significantly, the incidence of motion sickness in space travel is great: The majority of individuals in Shuttle operations suffer from the syndrome. Even after the space-sickness-producing influences of spatial disorientation dissipate, usually within several days, there are other situations in which, because of the absence of reliable or familiar vestibular cues, individuals in space still experience disorientation, resulting in a reliance on the already preoccupied sense of vision. One possible technique to minimize the deleterious effects of spatial disorientation might be to present attitude information (including orientation, direction, and motion) through another less-used sensory modality - the sense of touch. Data from experiences with deaf and blind persons indicate that this channel can provide useful communication and mobility information on a real-time basis. More recently, technologies have developed to present effective attitude information to pilots in situations in which dangerously ambiguous and conflicting visual and vestibular sensations occur. This summers project at NASA-Johnson Space Center will evaluate the influence of motion-based spatial disorientation on the perception of tactual stimuli representing veridical position and orientation information, presented by new dynamic vibrotactile array display technologies. In addition, the possibility will be explored that tactile presentations of motion and direction from this alternative modality might be useful in mitigating or alleviating spatial disorientation produced by multi-axis rotatory systems, monitored by physiological recording techniques developed at JSC.

The transition state for formation of the peptide bond in the ribosome

PubMed Central

Gindulyte, Asta; Bashan, Anat; Agmon, Ilana; Massa, Lou; Yonath, Ada; Karle, Jerome

2006-01-01

Using quantum mechanics and exploiting known crystallographic coordinates of tRNA substrate located in the ribosome peptidyl transferase center around the 2-fold axis, we have investigated the mechanism for peptide-bond formation. The calculation is based on a choice of 50 atoms assumed to be important in the mechanism. We used density functional theory to optimize the geometry and energy of the transition state (TS) for peptide-bond formation. The TS is formed simultaneously with the rotatory motion enabling the translocation of the A-site tRNA 3′ end into the P site, and we estimated the magnitude of rotation angle between the A-site starting position and the place at which the TS occurs. The calculated TS activation energy, Ea, is 35.5 kcal (1 kcal = 4.18 kJ)/mol, and the increase in hydrogen bonding between the rotating A-site tRNA and ribosome nucleotides as the TS forms appears to stabilize it to a value qualitatively estimated to be ≈18 kcal/mol. The optimized geometry corresponds to a structure in which the peptide bond is being formed as other bonds are being broken, in such a manner as to release the P-site tRNA so that it may exit as a free molecule and be replaced by the translocating A-site tRNA. At TS formation the 2′ OH group of the P-site tRNA A76 forms a hydrogen bond with the oxygen atom of the carboxyl group of the amino acid attached to the A-site tRNA, which may be indicative of its catalytic role, consistent with recent biochemical experiments. PMID:16938893

C1-C2 instability with severe occipital headache in the setting of vertebral artery facet complex erosion.

PubMed

Taher, Fadi; Bokums, Kristaps; Aichmair, Alexander; Hughes, Alexander P

2014-05-01

An exact understanding of patient vertebral artery anatomy is essential to safely place screws at the atlanto-axial level in posterior arthrodesis. We aim to report a case of erosion of the left vertebral artery into the C1-C2 facet complex with resultant rotatory and lateral listhesis presenting with severe occipital headache. This represents a novel etiology for this diagnosis and our report illustrates technical considerations when instrumenting the C1-C2 segment. We report a case of severe occipital headache due to C1-C2 instability with resultant left C2 nerve compression in the setting of erosion of the vertebral artery into the C1-C2 facet complex. A 68-year-old woman presented with a 12-month history of progressively debilitating headache and neck pain with atlanto-axial instability. Computed tomography (CT) angiography demonstrated erosion of the left vertebral artery into the left C1-C2 facet complex. In addition, the tortuous vertebral arteries had eroded into the C2 pedicles, eliminating the possibility for posterior pedicle screw placement. The patient underwent posterior arthrodesis of C1-C2 utilizing bilateral lateral mass fixation into C1 and bilateral trans-laminar fixation into C2 with resolution of all preoperative complaints. This study constitutes the first report of a tortuous vertebral artery causing the partial destruction of a C1-C2 facet complex, as well as instability, with the clinical presentation of severe occipital headache. It hereby presents a novel etiology for both the development of C1-C2 segment instability as well as the development of occipital headache. Careful evaluation of such lesions utilizing CT angiography is important when formulating a surgical plan.

Dynamic three-dimensional display of common congenital cardiac defects from reconstruction of two-dimensional echocardiographic images.

PubMed

Hsieh, K S; Lin, C C; Liu, W S; Chen, F L

1996-01-01

Two-dimensional echocardiography had long been a standard diagnostic modality for congenital heart disease. Further attempts of three-dimensional reconstruction using two-dimensional echocardiographic images to visualize stereotypic structure of cardiac lesions have been successful only recently. So far only very few studies have been done to display three-dimensional anatomy of the heart through two-dimensional image acquisition because such complex procedures were involved. This study introduced a recently developed image acquisition and processing system for dynamic three-dimensional visualization of various congenital cardiac lesions. From December 1994 to April 1995, 35 cases were selected in the Echo Laboratory here from about 3000 Echo examinations completed. Each image was acquired on-line with specially designed high resolution image grazmber with EKG and respiratory gating technique. Off-line image processing using a window-architectured interactive software package includes construction of 2-D ehcocardiographic pixel to 3-D "voxel" with conversion of orthogonal to rotatory axial system, interpolation, extraction of region of interest, segmentation, shading and, finally, 3D rendering. Three-dimensional anatomy of various congenital cardiac defects was shown, including four cases with ventricular septal defects, two cases with atrial septal defects, and two cases with aortic stenosis. Dynamic reconstruction of a "beating heart" is recorded as vedio tape with video interface. The potential application of 3D display of the reconstruction from 2D echocardiographic images for the diagnosis of various congenital heart defects has been shown. The 3D display was able to improve the diagnostic ability of echocardiography, and clear-cut display of the various congenital cardiac defects and vavular stenosis could be demonstrated. Reinforcement of current techniques will expand future application of 3D display of conventional 2D images.

The influence of polymeric component of bioactive glass-based nanocomposite paste on its rheological behaviors and in vitro responses: hyaluronic acid versus sodium alginate.

PubMed

Sohrabi, Mehri; Hesaraki, Saeed; Kazemzadeh, Asghar

2014-04-01

Different biocomposite pastes were prepared from a solid phase that was nanoparticles of sol-gel-derived bioactive glass and different liquid phases including 3% hyaluronic acid solution, sodium alginate solutions (3% and 10 %) or mixtures of hyaluronic acid and sodium alginate (3% or 10 %) solutions in 50:50 volume ratio. Rheological properties of the pastes were measured in both rotatory and oscillatory modes. The washout behavior and in vitro apatite formation of the pastes were determined by soaking them in simulated body fluid under dynamic situation for 14 days. The proliferation and alkaline phosphatase activity of MG-63 osteoblastic cells were also determined using extracts of the pastes. All pastes could be easily injected from the standard syringes with different tip diameters. All pastes exhibited visco-elastic character, but a nonthixotropic paste was obtained using hyaluronic acid in which the loss modulus was higher than the storage modulus. The thixotropy and storage modulus were increasingly improved by adding/using sodium alginate as mixing liquid. Moreover, the pastes in which the liquid phase was sodium alginate or mixture of hyaluronic acid and 10% sodium alginate solution revealed better apatite formation ability and washout resistance than that made of hyaluronic acid alone. No cytotoxicity effects were observed by extracts of the pastes on osteoblasts but better alkaline phosphatase activity was found for the pastes containing hyaluronic acid. Overall, injectable biocomposites can be produced by mixing bioactive glass nanoparticles and sodium alginate/hyaluronic acid polymers. They are potentially useful for hard and even soft tissues treatments. Copyright © 2013 Wiley Periodicals, Inc.

Anatomical versus non-anatomical single bundle anterior cruciate ligament reconstruction: a cadaveric study of comparison of knee stability.

PubMed

Lim, Hong-Chul; Yoon, Yong-Cheol; Wang, Joon-Ho; Bae, Ji-Hoon

2012-12-01

The purpose of this study was to compare the initial stability of anatomical and non-anatomical single bundle anterior cruciate ligament (ACL) reconstruction and to determine which would better restore intact knee kinematics. Our hypothesis was that the initial stability of anatomical single bundle ACL reconstruction would be superior to that of non-anatomical single bundle ACL reconstruction. Anterior tibial translation (ATT) and internal rotation of the tibia were measured with a computer navigation system in seven pairs of fresh-frozen cadaveric knees under two testing conditions (manual maximum anterior force, and a manual maximum anterior force combined with an internal rotational force). Tests were performed at 0, 30, 60, and 90 degrees of flexion with the ACL intact, the ACL transected, and after reconstruction of one side of a pair with either anatomical or non-anatomical single bundle ACL reconstruction. Under manual maximal anterior force, both reconstruction techniques showed no significant difference of ATT when compared to ACL intact knee state at 30° of knee flexion (p > 0.05). Under the combined anterior and internal rotatory force, non-anatomical single-bundle ACL reconstruction showed significant difference of ATT compared to those in ACL intact group (p < 0.05). In contrast, central anatomical single bundle ACL reconstruction showed no significant difference of ATT compared to those in ACL intact group (p > 0.05). Internal rotation of the tibia showed no significant difference in the ACL intact, the ACL transected, non-anatomical reconstructed and anatomical reconstructed knees. Anatomical single bundle ACL reconstruction restored the initial stability closer to the native ACL under combined anterior and internal rotational forces when compared to non-anatomical ACL single bundle reconstruction.

Effect of tibial positioning on the diagnosis of posterolateral rotatory instability in the posterior cruciate ligament-deficient knee.

PubMed

Strauss, Eric J; Ishak, Charbel; Inzerillo, Christopher; Walsh, Michael; Yildirim, Gokce; Walker, Peter; Jazrawi, Laith; Rosen, Jeffrey

2007-08-01

To determine whether positioning of the tibia affects the degree of tibial external rotation seen during a dial test in the posterior cruciate ligament (PCL)-posterolateral corner (PLC)-deficient knee. Laboratory investigation. Biomechanics laboratory. An anterior force applied to the tibia in the combined PCL-PLC-deficient knee will yield increased tibial external rotation during a dial test. The degree of tibial external rotation was measured with 5 Nm of external rotation torque applied to the tibia at both 30 degrees and 90 degrees of knee flexion. Before the torque was applied, an anterior force, a posterior force, or neutral (normal, reduced control) force was applied to the tibia. External rotation measurements were repeated after sequential sectioning of the PCL, the posterolateral structures and the fibular collateral ligament (FCL). Baseline testing of the intact specimens demonstrated a mean external rotation of 18.6 degrees with the knee flexed to 30 degrees (range 16.1-21.0 degrees ), and a mean external rotation of 17.3 degrees with the knee flexed to 90 degrees (range 13.8-20.0 degrees ). Sequential sectioning of the PCL, popliteus and popliteofibular ligament, and the FCL led to a significant increase in tibial external rotation compared with the intact knee for all testing scenarios. After sectioning of the popliteus and popliteofibular ligament, the application of an anterior force during testing led to a mean tibial external rotation that was 5 degrees greater than during testing in the neutral position and 7.5 degrees greater than during testing with a posterior force. In the PCL, popliteus/popliteofibular ligament and FCL-deficient knee, external rotation was 9 degrees and 12 degrees greater with the application of an anterior force during testing compared with neutral positioning and the application of a posterior force, respectively. An anterior force applied to the tibia during the dial test in a combined PCL-PLC-injured knee increased the overall amount of observed tibial external rotation during the dial test. The anterior force reduced the posterior tibial subluxation associated with PCL injury, which is analogous to what is observed when the dial test is performed with the patient in the prone position. Reducing the tibia with either an anterior force when the patient is supine or performing the dial test with the patient in the prone position increases the ability of an examiner to detect a concomitant PLC injury in the setting of a PCL-deficient knee.

Crystals in light.

PubMed

Kahr, Bart; Freudenthal, John; Gunn, Erica

2010-05-18

We have made images of crystals illuminated with polarized light for almost two decades. Early on, we abandoned photosensitive chemicals in favor of digital electrophotometry with all of the attendant advantages of quantitative intensity data. Accurate intensities are a boon because they can be used to analytically discriminate small effects in the presence of larger ones. The change in the form of our data followed camera technology that transformed picture taking the world over. Ironically, exposures in early photographs were presumed to correlate simply with light intensity, raising the hope that photography would replace sensorial interpretation with mechanical objectivity and supplant the art of visual photometry. This was only true in part. Quantitative imaging accurate enough to render the separation of crystalloptical quantities had to await the invention of the solid-state camera. Many pioneers in crystal optics were also major figures in the early history of photography. We draw out the union of optical crystallography and photography because the tree that connects the inventors of photography is a structure unmatched for organizing our work during the past 20 years, not to mention that silver halide crystallites used in chemical photography are among the most consequential "crystals in light", underscoring our title. We emphasize crystals that have acquired optical properties such as linear birefringence, linear dichroism, circular birefringence, and circular dichroism, during growth from solution. Other crystalloptical effects were discovered that are unique to curiously dissymmetric crystals containing embedded oscillators. In the aggregate, dyed crystals constitute a generalization of single crystal matrix isolation. Simple crystals provided kinetic stability to include guests such as proteins or molecules in excited states. Molecular lifetimes were extended for the preparation of laser gain media and for the study of the photodynamics of single molecules. Luminophores were used as guests in crystals to reveal aspects of growth mechanisms by labeling surface structures such as steps and kinks. New methods were adopted for measuring and imaging the optical rotatory power of crystals. Chiroptical anisotropies can now be compared with the results of quantum chemical calculations that have emerged in the past 10 years. The rapid determination of the optical rotation and circular dichroism tensors of molecules in crystals, and the interpretation of these anisotropies, remains a subject of future research. Polycrystalline patterns that form far from equilibrium challenged the quantitative interpretation of micrographs when heterogeneities along the optical path and obliquely angled interfaces played large roles. Resulting "artifacts" were nevertheless incisive probes of polycrystalline texture and mesoscale chemistry in simple substances grown far from equilibrium or in biopathological crystals such as Alzheimer's amyloid plaques.

Fiber optical cable and connector system (FOCCoS) for PFS/ Subaru

NASA Astrophysics Data System (ADS)

de Oliveira, Antonio Cesar; de Oliveira, Lígia Souza; de Arruda, Marcio V.; Souza Marrara, Lucas; dos Santos, Leandro H.; Ferreira, Décio; dos Santos, Jesulino B.; Rosa, Josimar A.; Junior, Orlando V.; Pereira, Jeferson M.; Castilho, Bruno; Gneiding, Clemens; Junior, Laerte S.; de Oliveira, Claudia M.; Gunn, James; Ueda, Akitoshi; Takato, Naruhisa; Shimono, Atsushi; Sugai, Hajime; Karoji, Hiroshi; Kimura, Masahiko; Tamura, Naoyuki; Wang, Shiang-Yu; Murray, Graham; Le Mignant, David; Madec, Fabrice; Jaquet, Marc; Vives, Sebastien; Fisher, Charlie; Braun, David; Schwochert, Mark; Reiley, Daniel J.

2014-07-01

FOCCoS, "Fiber Optical Cable and Connector System" has the main function of capturing the direct light from the focal plane of Subaru Telescope using optical fibers, each one with a microlens in its tip, and conducting this light through a route containing connectors to a set of four spectrographs. The optical fiber cable is divided in 3 different segments called Cable A, Cable B and Cable C. Multi-fibers connectors assure precise connection among all optical fibers of the segments, providing flexibility for instrument changes. To assure strong and accurate connection, these sets are arranged inside two types of assemblies: the Tower Connector, for connection between Cable C and Cable B; and the Gang Connector, for connection between Cable B and Cable A. Throughput tests were made to evaluate the efficiency of the connections. A lifetime test connection is in progress. Cable C is installed inside the PFI, Prime Focus Instrument, where each fiber tip with a microlens is bonded to the end of the shaft of a 2-stage piezo-electric rotatory motor positioner; this assembly allows each fiber to be placed anywhere within its patrol region, which is 9.5mm diameter.. Each positioner uses a fiber arm to support the ferrule, the microlens, and the optical fiber. 2400 of these assemblies are arranged on a motor bench plate in a hexagonal-closed-packed disposition. All optical fibers from Cable C, protected by tubes, pass through the motors' bench plate, three modular plates and a strain relief box, terminating at the Tower Connector. Cable B is permanently installed at Subaru Telescope structure, as a link between Cable C and Cable A. This cable B starts at the Tower Connector device, placed on a lateral structure of the telescope, and terminates at the Gang Connector device. Cable B will be routed to minimize the compression, torsion and bending caused by the cable weight and telescope motion. In the spectrograph room, Cable A starts at the Gang Connector, crosses a distribution box and terminates in a slit device. Each slit device receives approximately 600 optical fibers, linearly arrayed in a curve for better orientation of the light to the spectrograph collimator mirror. Four sets of Gang Connectors, distribution boxes and Slit devices complete one Cable A. This paper will review the general design of the FOCCoS subsystem, methods used to manufacture the involved devices, and the needed tests results to evaluate the total efficiency of the set.

Birth Control Methods

MedlinePlus

... Z Health Topics Birth control methods Birth control methods > A-Z Health Topics Birth control methods fact ... To receive Publications email updates Submit Birth control methods Birth control (contraception) is any method, medicine, or ...

A comparison of two non-thrust mobilization techniques applied to the C7 segment in patients with restricted and painful cervical rotation.

PubMed

Creighton, Doug; Gruca, Mark; Marsh, Douglas; Murphy, Nancy

2014-11-01

Cervical mobilization and manipulation have been shown to improve cervical range of motion and pain. Rotatory thrust manipulation applied to the lower cervical segments is associated with controversy and the potential for eliciting adverse reactions (AR). The purpose of this clinical trial was to describe two translatory non-thrust mobilization techniques and evaluate their effect on cervical pain, motion restriction, and whether any adverse effects were reported when applied to the C7 segment. This trial included 30 participants with painful and restricted cervical rotation. Participants were randomly assigned to receive one of the two mobilization techniques. Active cervical rotation and pain intensity measurements were recorded pre- and post-intervention. Within group comparisons were determined using the Wilcoxon signed-rank test and between group comparisons were analyzed using the Mann-Whitney U test. Significance was set at P = 0.05. Thirty participants were evaluated immediately after one of the two mobilization techniques was applied. There was a statistically significant difference (improvement) for active cervical rotation after application of the C7 facet distraction technique for both right (P = 0.022) and left (P = 0.022) rotation. Statistically significant improvement was also found for the C7 facet gliding technique for both right (P = 0.022) and left rotation (P = 0.020). Pain reduction was statistically significant for both right and left rotation after application of both techniques. Both mobilization techniques produced similar positive effects and one was not statistically superior to the other. A single application of both C7 mobilization techniques improved active cervical rotation, reduced perceived pain, and did not produce any AR in 30 patients with neck pain and movement limitation. These two non-thrust techniques may offer clinicians an additional safe and effective manual intervention for patients with limited and painful cervical rotation. A more robust experimental design is recommended to further examine these and similar cervical translatory mobilization techniques.

Evaluation of the slurry management strategy and the integration of the composting technology in a pig farm - Agronomical and environmental implications.

PubMed

Sáez, José A; Clemente, Rafael; Bustamante, M Ángeles; Yañez, David; Bernal, M Pilar

2017-05-01

The changes in livestock production systems towards intensification frequently lead to an excess of manure generation with respect to the agricultural land available for its soil application. However, treatment technologies can help in the management of manures, especially in N-surplus areas. An integrated slurry treatment system based on solid-liquid separation, aerobic treatment of the liquid and composting the solid fraction was evaluated in a pig farm (sows and piglets) in the South of Spain. Solid fraction separation using a filter band connected to a screw press had low efficiency (38%), which was greatly improved incorporating a rotatory sieve (61%). The depuration system was very efficient for the liquid, with total removal of 84% total solids, 87% volatile solids, and 98% phosphorus. Two composting systems were tested through mechanical turning of: 1- a mixture of solid fraction stored for 1 month after solid-liquid separation and cereal straw; 2- recently-separated solid fraction mixed with cotton gin waste. System 2 was recommended for the farm, as it exhibited a fast temperature rise and a long thermophilic phase to ensure compost sanitisation, and high recovery of nutrients (TN 77%, P and K > 85%) and organic matter (45%). The composts obtained were mature, stable and showed a high degree of humification of their organic matter, absence of phytotoxicity and concentrations of nutrients similar to other composts from pig manure or separated slurry solids. However, the introduction of slurry from piglets into the solid-liquid separation system should be avoided in order to reduce the content of Zn in the compost, which lowers its quality. The slurry separation followed by composting of the solid fraction using a passive windrow system, and aeration of the liquid phase, was the most recommendable procedure for the reduction of GHG emissions on the farm. Copyright © 2017 Elsevier Ltd. All rights reserved.

Snapping plicae associated with radiocapitellar chondromalacia.

PubMed

Antuna, S A; O'Driscoll, S W

2001-05-01

Painful snapping of the elbow joint is usually attributed to intra-articular loose bodies, instability, or medial dislocation of the triceps muscle over the medial epicondyle. We report our experience with 14 patients who were treated arthroscopically for snapping elbow that was found to be caused by hypertrophic synovial folds associated with radiocapitellar chondromalacia. Case series. The records of 14 patients who were treated arthroscopically for painful snapping elbows caused by intra-articular plicae were reviewed. There were 6 women and 8 men with an average age of 36 years (range, 27 to 48 years). Nine patients had had some type of trauma to the joint. Four patients had been previously diagnosed with lateral epicondylitis and 5 with intra-articular loose bodies. The average time from initial onset of symptoms to treatment was 13 months (range, 8 to 36 months). Average follow-up was 24 months (range, 6 to 66 months). All patients complained of painful snapping in the posterolateral or anterolateral aspect of the elbow. The snapping occurred between 90 degrees and 110 degrees of flexion with the forearm in pronation. In 7 patients, the snapping was reproducible by passively flexing the pronated elbow, which we refer to as the flexion-pronation test. At the time of arthroscopic surgery, all patients had a thickened synovial plica that would snap back and forward over the radial head, usually associated with a chondromalacic area on the radial head. Twelve patients had complete relief of their snapping after surgery. One patient in whom there was associated posterolateral rotatory elbow instability did not improve. One patient became asymptomatic for 4 years but then had recurrence of her symptoms, which persisted despite 2 subsequent arthroscopies. The presence of synovial plicae in the radiocapitellar joint must be considered in the differential diagnosis of painful snapping elbow. Arthroscopy confirms the diagnosis and allows excision of the plica.

Clinical significance of achieving a flexion limitation with a tension band system in grade 1 degenerative spondylolisthesis: a minimum 5-year follow-up.

PubMed

Lee, Sang-Ho; Lee, Ho-Yeon; Baek, Oon Ki; Bae, Jun Seok; Yoo, Seung-Hwa; Lee, June-Ho

2015-03-15

Retrospective clinical study. To evaluate the effect of the limitation of flexion rotation clinically and radiologically after interspinous soft stabilization using a tension band system in grade 1 degenerative spondylolisthesis. Although several studies have been published on the clinical effects of limiting rotatory motion using tension band systems, which mainly targets the limitation of flexion rather than that of extension, they were confined to the category of pedicle screw-based systems, revealing inconsistent long-term outcomes. Sixty-one patients with a mean age of 60.6 years (range, 28-76 yr) who underwent interspinous soft stabilization after decompression for grade 1 degenerative spondylolisthesis with stenosis between 2002 and 2004 were analyzed. At follow-up, the patients were divided into 2 groups on the basis of their achievement or failure to achieve flexion limitation. The clinical and radiological findings were analyzed. A multiple linear regression analysis was performed to determine the prognostic factors for surgical outcomes. At a mean follow-up duration of 72.5 months (range, 61-82 mo), 51 patients were classified into the flexion-limited group and 10 into the flexion-unlimited group. Statistically significant improvements were noted only in the flexion-limited group in all clinical scores. In the flexion-unlimited group, there were significant deteriorations in flexion angle (P = 0.009), axial thickness of the ligamentum flavum (P = 0.013), and the foraminal cross-sectional area (P = 0.011), resulting in significant intergroup differences. The preoperative extension angle was identified as the most influential variable for the flexion limitation and the clinical outcomes. The effects of the limitation of flexion rotation achieved through interspinous soft stabilization using a tension band system after decompression were related to the prevention of late recurrent stenosis and resultant radicular pain caused by flexion instability. The extension potential at the index level was recognized as a major prognostic factor that can predict the flexion limitation and the clinical results. 4.

Real-time performance assessment and adaptive control for a water chiller unit in an HVAC system

NASA Astrophysics Data System (ADS)

Bai, Jianbo; Li, Yang; Chen, Jianhao

2018-02-01

The paper proposes an adaptive control method for a water chiller unit in a HVAC system. Based on the minimum variance evaluation, the adaptive control method was used to realize better control of the water chiller unit. To verify the performance of the adaptive control method, the proposed method was compared with an a conventional PID controller, the simulation results showed that adaptive control method had superior control performance to that of the conventional PID controller.

Manipulation and mobilisation for neck pain contrasted against an inactive control or another active treatment.

PubMed

Gross, Anita; Langevin, Pierre; Burnie, Stephen J; Bédard-Brochu, Marie-Sophie; Empey, Brian; Dugas, Estelle; Faber-Dobrescu, Michael; Andres, Cristy; Graham, Nadine; Goldsmith, Charles H; Brønfort, Gert; Hoving, Jan L; LeBlanc, Francis

2015-09-23

Manipulation and mobilisation are commonly used to treat neck pain. This is an update of a Cochrane review first published in 2003, and previously updated in 2010. To assess the effects of manipulation or mobilisation alone compared wiith those of an inactive control or another active treatment on pain, function, disability, patient satisfaction, quality of life and global perceived effect in adults experiencing neck pain with or without radicular symptoms and cervicogenic headache (CGH) at immediate- to long-term follow-up. When appropriate, to assess the influence of treatment characteristics (i.e. technique, dosage), methodological quality, symptom duration and subtypes of neck disorder on treatment outcomes. Review authors searched the following computerised databases to November 2014 to identify additional studies: the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Cumulative Index to Nursing and Allied Health Literature (CINAHL). We also searched ClinicalTrials.gov, checked references, searched citations and contacted study authors to find relevant studies. We updated this search in June 2015, but these results have not yet been incorporated. Randomised controlled trials (RCTs) undertaken to assess whether manipulation or mobilisation improves clinical outcomes for adults with acute/subacute/chronic neck pain. Two review authors independently selected studies, abstracted data, assessed risk of bias and applied Grades of Recommendation, Assessment, Development and Evaluation (GRADE) methods (very low, low, moderate, high quality). We calculated pooled risk ratios (RRs) and standardised mean differences (SMDs). We included 51 trials (2920 participants, 18 trials of manipulation/mobilisation versus control; 34 trials of manipulation/mobilisation versus another treatment, 1 trial had two comparisons). Cervical manipulation versus inactive control: For subacute and chronic neck pain, a single manipulation (three trials, no meta-analysis, 154 participants, ranged from very low to low quality) relieved pain at immediate- but not short-term follow-up. Cervical manipulation versus another active treatment: For acute and chronic neck pain, multiple sessions of cervical manipulation (two trials, 446 participants, ranged from moderate to high quality) produced similar changes in pain, function, quality of life (QoL), global perceived effect (GPE) and patient satisfaction when compared with multiple sessions of cervical mobilisation at immediate-, short- and intermediate-term follow-up. For acute and subacute neck pain, multiple sessions of cervical manipulation were more effective than certain medications in improving pain and function at immediate- (one trial, 182 participants, moderate quality) and long-term follow-up (one trial, 181 participants, moderate quality). These findings are consistent for function at intermediate-term follow-up (one trial, 182 participants, moderate quality). For chronic CGH, multiple sessions of cervical manipulation (two trials, 125 participants, low quality) may be more effective than massage in improving pain and function at short/intermediate-term follow-up. Multiple sessions of cervical manipulation (one trial, 65 participants, very low quality) may be favoured over transcutaneous electrical nerve stimulation (TENS) for pain reduction at short-term follow-up. For acute neck pain, multiple sessions of cervical manipulation (one trial, 20 participants, very low quality) may be more effective than thoracic manipulation in improving pain and function at short/intermediate-term follow-up. Thoracic manipulation versus inactive control: Three trials (150 participants) using a single session were assessed at immediate-, short- and intermediate-term follow-up. At short-term follow-up, manipulation improved pain in participants with acute and subacute neck pain (five trials, 346 participants, moderate quality, pooled SMD -1.26, 95% confidence interval (CI) -1.86 to -0.66) and improved function (four trials, 258 participants, moderate quality, pooled SMD -1.40, 95% CI -2.24 to -0.55) in participants with acute and chronic neck pain. A funnel plot of these data suggests publication bias. These findings were consistent at intermediate follow-up for pain/function/quality of life (one trial, 111 participants, low quality). Thoracic manipulation versus another active treatment: No studies provided sufficient data for statistical analyses. A single session of thoracic manipulation (one trial, 100 participants, moderate quality) was comparable with thoracic mobilisation for pain relief at immediate-term follow-up for chronic neck pain. Mobilisation versus inactive control: Mobilisation as a stand-alone intervention (two trials, 57 participants, ranged from very low to low quality) may not reduce pain more than an inactive control. Mobilisation versus another active treatment: For acute and subacute neck pain, anterior-posterior mobilisation (one trial, 95 participants, very low quality) may favour pain reduction over rotatory or transverse mobilisations at immediate-term follow-up. For chronic CGH with temporomandibular joint (TMJ) dysfunction, multiple sessions of TMJ manual therapy (one trial, 38 participants, very low quality) may be more effective than cervical mobilisation in improving pain/function at immediate- and intermediate-term follow-up. For subacute and chronic neck pain, cervical mobilisation alone (four trials, 165 participants, ranged from low to very low quality) may not be different from ultrasound, TENS, acupuncture and massage in improving pain, function, QoL and participant satisfaction at immediate- and intermediate-term follow-up. Additionally, combining laser with manipulation may be superior to using manipulation or laser alone (one trial, 56 participants, very low quality). Although support can be found for use of thoracic manipulation versus control for neck pain, function and QoL, results for cervical manipulation and mobilisation versus control are few and diverse. Publication bias cannot be ruled out. Research designed to protect against various biases is needed. Findings suggest that manipulation and mobilisation present similar results for every outcome at immediate/short/intermediate-term follow-up. Multiple cervical manipulation sessions may provide better pain relief and functional improvement than certain medications at immediate/intermediate/long-term follow-up. Since the risk of rare but serious adverse events for manipulation exists, further high-quality research focusing on mobilisation and comparing mobilisation or manipulation versus other treatment options is needed to guide clinicians in their optimal treatment choices.

Two Reconfigurable Flight-Control Design Methods: Robust Servomechanism and Control Allocation

NASA Technical Reports Server (NTRS)

Burken, John J.; Lu, Ping; Wu, Zheng-Lu; Bahm, Cathy

2001-01-01

Two methods for control system reconfiguration have been investigated. The first method is a robust servomechanism control approach (optimal tracking problem) that is a generalization of the classical proportional-plus-integral control to multiple input-multiple output systems. The second method is a control-allocation approach based on a quadratic programming formulation. A globally convergent fixed-point iteration algorithm has been developed to make onboard implementation of this method feasible. These methods have been applied to reconfigurable entry flight control design for the X-33 vehicle. Examples presented demonstrate simultaneous tracking of angle-of-attack and roll angle commands during failures of the fight body flap actuator. Although simulations demonstrate success of the first method in most cases, the control-allocation method appears to provide uniformly better performance in all cases.

A Robust Cooperated Control Method with Reinforcement Learning and Adaptive H∞ Control

NASA Astrophysics Data System (ADS)

Obayashi, Masanao; Uchiyama, Shogo; Kuremoto, Takashi; Kobayashi, Kunikazu

This study proposes a robust cooperated control method combining reinforcement learning with robust control to control the system. A remarkable characteristic of the reinforcement learning is that it doesn't require model formula, however, it doesn't guarantee the stability of the system. On the other hand, robust control system guarantees stability and robustness, however, it requires model formula. We employ both the actor-critic method which is a kind of reinforcement learning with minimal amount of computation to control continuous valued actions and the traditional robust control, that is, H∞ control. The proposed system was compared method with the conventional control method, that is, the actor-critic only used, through the computer simulation of controlling the angle and the position of a crane system, and the simulation result showed the effectiveness of the proposed method.

Resonant power processors. II - Methods of control

NASA Technical Reports Server (NTRS)

Oruganti, R.; Lee, F. C.

1984-01-01

The nature of resonant converter control is discussed. Employing the state-portrait, different control methods for series resonant converter are identified and their performance evaluated based on their stability, response to control and load changes and range of operation. A new control method, optimal-trajectory control, is proposed which, by utilizing the state trajectories as control laws, continuously monitors the energy level of the resonant tank. The method is shown to have superior control properties especially under transient operation.

Reverse matrix converter control method for PMSM drives using DPC

NASA Astrophysics Data System (ADS)

Bak, Yeongsu; Lee, Kyo-Beum

2018-05-01

This paper proposes a control method for a reverse matrix converter (RMC) that drives a three-phase permanent magnet synchronous motor (PMSM). In this proposed method, direct power control (DPC) is used to control the voltage source rectifier of the RMC. The RMC is an indirect matrix converter operating in the boost mode, in which the power-flow directions of the input and output are switched. It has a minimum voltage transfer ratio of 1/0.866 in a linear-modulation region. In this paper, a control method that uses DPC as an additional control method is proposed in order to control the RMC driving a PMSM in the output stage. Simulations and experimental results verify the effectiveness of the proposed control method.

Adaptive Importance Sampling for Control and Inference

NASA Astrophysics Data System (ADS)

Kappen, H. J.; Ruiz, H. C.

2016-03-01

Path integral (PI) control problems are a restricted class of non-linear control problems that can be solved formally as a Feynman-Kac PI and can be estimated using Monte Carlo sampling. In this contribution we review PI control theory in the finite horizon case. We subsequently focus on the problem how to compute and represent control solutions. We review the most commonly used methods in robotics and control. Within the PI theory, the question of how to compute becomes the question of importance sampling. Efficient importance samplers are state feedback controllers and the use of these requires an efficient representation. Learning and representing effective state-feedback controllers for non-linear stochastic control problems is a very challenging, and largely unsolved, problem. We show how to learn and represent such controllers using ideas from the cross entropy method. We derive a gradient descent method that allows to learn feed-back controllers using an arbitrary parametrisation. We refer to this method as the path integral cross entropy method or PICE. We illustrate this method for some simple examples. The PI control methods can be used to estimate the posterior distribution in latent state models. In neuroscience these problems arise when estimating connectivity from neural recording data using EM. We demonstrate the PI control method as an accurate alternative to particle filtering.

A survey of methods of feasible directions for the solution of optimal control problems

NASA Technical Reports Server (NTRS)

Polak, E.

1972-01-01

Three methods of feasible directions for optimal control are reviewed. These methods are an extension of the Frank-Wolfe method, a dual method devised by Pironneau and Polack, and a Zontendijk method. The categories of continuous optimal control problems are shown as: (1) fixed time problems with fixed initial state, free terminal state, and simple constraints on the control; (2) fixed time problems with inequality constraints on both the initial and the terminal state and no control constraints; (3) free time problems with inequality constraints on the initial and terminal states and simple constraints on the control; and (4) fixed time problems with inequality state space contraints and constraints on the control. The nonlinear programming algorithms are derived for each of the methods in its associated category.

Reconfigurable Flight Control Designs With Application to the X-33 Vehicle

NASA Technical Reports Server (NTRS)

Burken, John J.; Lu, Ping; Wu, Zhenglu

1999-01-01

Two methods for control system reconfiguration have been investigated. The first method is a robust servomechanism control approach (optimal tracking problem) that is a generalization of the classical proportional-plus-integral control to multiple input-multiple output systems. The second method is a control-allocation approach based on a quadratic programming formulation. A globally convergent fixed-point iteration algorithm has been developed to make onboard implementation of this method feasible. These methods have been applied to reconfigurable entry flight control design for the X-33 vehicle. Examples presented demonstrate simultaneous tracking of angle-of-attack and roll angle commands during failures of the right body flap actuator. Although simulations demonstrate success of the first method in most cases, the control-allocation method appears to provide uniformly better performance in all cases.

Effect of chemical and mechanical weed control on cassava yield, soil quality and erosion under cassava cropping system

NASA Astrophysics Data System (ADS)

Islami, Titiek; Wisnubroto, Erwin; Utomo, Wani

2016-04-01

Three years field experiments were conducted to study the effect of chemical and mechanical weed control on soil quality and erosion under cassava cropping system. The experiment were conducted at University Brawijaya field experimental station, Jatikerto, Malang, Indonesia. The experiments were carried out from 2011 - 2014. The treatments consist of three cropping system (cassava mono culture; cassava + maize intercropping and cassava + peanut intercropping), and two weed control method (chemical and mechanical methods). The experimental result showed that the yield of cassava first year and second year did not influenced by weed control method and cropping system. However, the third year yield of cassava was influence by weed control method and cropping system. The cassava yield planted in cassava + maize intercropping system with chemical weed control methods was only 24 t/ha, which lower compared to other treatments, even with that of the same cropping system used mechanical weed control. The highest cassava yield in third year was obtained by cassava + peanuts cropping system with mechanical weed control method. After three years experiment, the soil of cassava monoculture system with chemical weed control method possessed the lowest soil organic matter, and soil aggregate stability. During three years of cropping soil erosion in chemical weed control method, especially on cassava monoculture, was higher compared to mechanical weed control method. The soil loss from chemical control method were 40 t/ha, 44 t/ha and 54 t/ha for the first, second and third year crop. The soil loss from mechanical weed control method for the same years was: 36 t/ha, 36 t/ha and 38 t/ha. Key words: herbicide, intercropping, soil organic matter, aggregate stability.

Seminar on Understanding Digital Control and Analysis in Vibration Test Systems

NASA Technical Reports Server (NTRS)

1975-01-01

The advantages of the digital methods over the analog vibration methods are demonstrated. The following topics are covered: (1) methods of computer-controlled random vibration and reverberation acoustic testing, (2) methods of computer-controlled sinewave vibration testing, and (3) methods of computer-controlled shock testing. General algorithms are described in the form of block diagrams and flow diagrams.

Control system and method for payload control in mobile platform cranes

DOEpatents

Robinett, III, Rush D.; Groom, Kenneth N.; Feddema, John T.; Parker, Gordon G.

2002-01-01

A crane control system and method provides a way to generate crane commands responsive to a desired payload motion to achieve substantially pendulation-free actual payload motion. The control system and method apply a motion compensator to maintain a payload in a defined payload configuration relative to an inertial coordinate frame. The control system and method can further comprise a pendulation damper controller to reduce an amount of pendulation between a sensed payload configuration and the defined payload configuration. The control system and method can further comprise a command shaping filter to filter out a residual payload pendulation frequency from the desired payload motion.

Methods to control for unmeasured confounding in pharmacoepidemiology: an overview.

PubMed

Uddin, Md Jamal; Groenwold, Rolf H H; Ali, Mohammed Sanni; de Boer, Anthonius; Roes, Kit C B; Chowdhury, Muhammad A B; Klungel, Olaf H

2016-06-01

Background Unmeasured confounding is one of the principal problems in pharmacoepidemiologic studies. Several methods have been proposed to detect or control for unmeasured confounding either at the study design phase or the data analysis phase. Aim of the Review To provide an overview of commonly used methods to detect or control for unmeasured confounding and to provide recommendations for proper application in pharmacoepidemiology. Methods/Results Methods to control for unmeasured confounding in the design phase of a study are case only designs (e.g., case-crossover, case-time control, self-controlled case series) and the prior event rate ratio adjustment method. Methods that can be applied in the data analysis phase include, negative control method, perturbation variable method, instrumental variable methods, sensitivity analysis, and ecological analysis. A separate group of methods are those in which additional information on confounders is collected from a substudy. The latter group includes external adjustment, propensity score calibration, two-stage sampling, and multiple imputation. Conclusion As the performance and application of the methods to handle unmeasured confounding may differ across studies and across databases, we stress the importance of using both statistical evidence and substantial clinical knowledge for interpretation of the study results.

Quasi-modal vibration control by means of active control bearings

NASA Technical Reports Server (NTRS)

Nonami, K.; Fleming, D. P.

1986-01-01

This paper investigates a design method of an active control bearing system with only velocity feedback. The study provides a new quasi-modal control method for a control system design of an active control bearing system in which feedback coefficients are determined on the basis of a modal analysis. Although the number of sensors and actuators is small, this quasi-modal control method produces a control effect close to an ideal modal control.

Steering Quantum Dynamics of a Two-Qubit System via Optimal Bang-Bang Control

NASA Astrophysics Data System (ADS)

Hu, Juju; Ke, Qiang; Ji, Yinghua

2018-02-01

The optimization of control time for quantum systems has been an important field of control science attracting decades of focus, which is beneficial for efficiency improvement and decoherence suppression caused by the environment. Based on analyzing the advantages and disadvantages of the existing Lyapunov control, using a bang-bang optimal control technique, we investigate the fast state control in a closed two-qubit quantum system, and give three optimized control field design methods. Numerical simulation experiments indicate the effectiveness of the methods. Compared to the standard Lyapunov control or standard bang-bang control method, the optimized control field design methods effectively shorten the state control time and avoid high-frequency oscillation that occurs in bang-bang control.

Synchronous Control Method and Realization of Automated Pharmacy Elevator

NASA Astrophysics Data System (ADS)

Liu, Xiang-Quan

Firstly, the control method of elevator's synchronous motion is provided, the synchronous control structure of double servo motor based on PMAC is accomplished. Secondly, synchronous control program of elevator is implemented by using PMAC linear interpolation motion model and position error compensation method. Finally, the PID parameters of servo motor were adjusted. The experiment proves the control method has high stability and reliability.

Force control compensation method with variable load stiffness and damping of the hydraulic drive unit force control system

NASA Astrophysics Data System (ADS)

Kong, Xiangdong; Ba, Kaixian; Yu, Bin; Cao, Yuan; Zhu, Qixin; Zhao, Hualong

2016-05-01

Each joint of hydraulic drive quadruped robot is driven by the hydraulic drive unit (HDU), and the contacting between the robot foot end and the ground is complex and variable, which increases the difficulty of force control inevitably. In the recent years, although many scholars researched some control methods such as disturbance rejection control, parameter self-adaptive control, impedance control and so on, to improve the force control performance of HDU, the robustness of the force control still needs improving. Therefore, how to simulate the complex and variable load characteristics of the environment structure and how to ensure HDU having excellent force control performance with the complex and variable load characteristics are key issues to be solved in this paper. The force control system mathematic model of HDU is established by the mechanism modeling method, and the theoretical models of a novel force control compensation method and a load characteristics simulation method under different environment structures are derived, considering the dynamic characteristics of the load stiffness and the load damping under different environment structures. Then, simulation effects of the variable load stiffness and load damping under the step and sinusoidal load force are analyzed experimentally on the HDU force control performance test platform, which provides the foundation for the force control compensation experiment research. In addition, the optimized PID control parameters are designed to make the HDU have better force control performance with suitable load stiffness and load damping, under which the force control compensation method is introduced, and the robustness of the force control system with several constant load characteristics and the variable load characteristics respectively are comparatively analyzed by experiment. The research results indicate that if the load characteristics are known, the force control compensation method presented in this paper has positive compensation effects on the load characteristics variation, i.e., this method decreases the effects of the load characteristics variation on the force control performance and enhances the force control system robustness with the constant PID parameters, thereby, the online PID parameters tuning control method which is complex needs not be adopted. All the above research provides theoretical and experimental foundation for the force control method of the quadruped robot joints with high robustness.

Virtual Passive Controller for Robot Systems Using Joint Torque Sensors

NASA Technical Reports Server (NTRS)

Aldridge, Hal A.; Juang, Jer-Nan

1997-01-01

This paper presents a control method based on virtual passive dynamic control that will stabilize a robot manipulator using joint torque sensors and a simple joint model. The method does not require joint position or velocity feedback for stabilization. The proposed control method is stable in the sense of Lyaponov. The control method was implemented on several joints of a laboratory robot. The controller showed good stability robustness to system parameter error and to the exclusion of nonlinear dynamic effects on the joints. The controller enhanced position tracking performance and, in the absence of position control, dissipated joint energy.

A decentralized linear quadratic control design method for flexible structures

NASA Technical Reports Server (NTRS)

Su, Tzu-Jeng; Craig, Roy R., Jr.

1990-01-01

A decentralized suboptimal linear quadratic control design procedure which combines substructural synthesis, model reduction, decentralized control design, subcontroller synthesis, and controller reduction is proposed for the design of reduced-order controllers for flexible structures. The procedure starts with a definition of the continuum structure to be controlled. An evaluation model of finite dimension is obtained by the finite element method. Then, the finite element model is decomposed into several substructures by using a natural decomposition called substructuring decomposition. Each substructure, at this point, still has too large a dimension and must be reduced to a size that is Riccati-solvable. Model reduction of each substructure can be performed by using any existing model reduction method, e.g., modal truncation, balanced reduction, Krylov model reduction, or mixed-mode method. Then, based on the reduced substructure model, a subcontroller is designed by an LQ optimal control method for each substructure independently. After all subcontrollers are designed, a controller synthesis method called substructural controller synthesis is employed to synthesize all subcontrollers into a global controller. The assembling scheme used is the same as that employed for the structure matrices. Finally, a controller reduction scheme, called the equivalent impulse response energy controller (EIREC) reduction algorithm, is used to reduce the global controller to a reasonable size for implementation. The EIREC reduced controller preserves the impulse response energy of the full-order controller and has the property of matching low-frequency moments and low-frequency power moments. An advantage of the substructural controller synthesis method is that it relieves the computational burden associated with dimensionality. Besides that, the SCS design scheme is also a highly adaptable controller synthesis method for structures with varying configuration, or varying mass and stiffness properties.

Modified independent modal space control method for active control of flexible systems

NASA Technical Reports Server (NTRS)

Baz, A.; Poh, S.

1987-01-01

A modified independent modal space control (MIMSC) method is developed for designing active vibration control systems for large flexible structures. The method accounts for the interaction between the controlled and residual modes. It incorporates also optimal placement procedures for selecting the optimal locations of the actuators in the structure in order to minimize the structural vibrations as well as the actuation energy. The MIMSC method relies on an important feature which is based on time sharing of a small number of actuators, in the modal space, to control effectively a large number of modes. Numerical examples are presented to illustrate the application of the method to generic flexible systems. The results obtained suggest the potential of the devised method in designing efficient active control systems for large flexible structures.

Experimental Comparison of two Active Vibration Control Approaches: Velocity Feedback and Negative Capacitance Shunt Damping

NASA Technical Reports Server (NTRS)

Beck, Benjamin; Schiller, Noah

2013-01-01

This paper outlines a direct, experimental comparison between two established active vibration control techniques. Active vibration control methods, many of which rely upon piezoelectric patches as actuators and/or sensors, have been widely studied, showing many advantages over passive techniques. However, few direct comparisons between different active vibration control methods have been made to determine the performance benefit of one method over another. For the comparison here, the first control method, velocity feedback, is implemented using four accelerometers that act as sensors along with an analog control circuit which drives a piezoelectric actuator. The second method, negative capacitance shunt damping, consists of a basic analog circuit which utilizes a single piezoelectric patch as both a sensor and actuator. Both of these control methods are implemented individually using the same piezoelectric actuator attached to a clamped Plexiglas window. To assess the performance of each control method, the spatially averaged velocity of the window is compared to an uncontrolled response.

Division by zero, pseudo-division by zero, Zhang dynamics method and Zhang-gradient method about control singularity conquering

NASA Astrophysics Data System (ADS)

Zhang, Yunong; Zhang, Yinyan; Chen, Dechao; Xiao, Zhengli; Yan, Xiaogang

2017-01-01

In this paper, the division-by-zero (DBO) problem in the field of nonlinear control, which is traditionally termed the control singularity problem (or specifically, controller singularity problem), is investigated by the Zhang dynamics (ZD) method and the Zhang-gradient (ZG) method. According to the impact of the DBO problem on the state variables of the controlled nonlinear system, the concepts of the pseudo-DBO problem and the true-DBO problem are proposed in this paper, which provide a new perspective for the researchers on the DBO problems as well as nonlinear control systems. Besides, the two classes of DBO problems are solved under the framework of the ZG method. Specific examples are shown and investigated in this paper to illustrate the two proposed concepts and the efficacy of the ZG method in conquering pseudo-DBO and true-DBO problems. The application of the ZG method to the tracking control of a two-wheeled mobile robot further substantiates the effectiveness of the ZG method. In addition, the ZG method is successfully applied to the tracking control of a pure-feedback nonlinear system.

Near-Optimal Tracking Control of Mobile Robots Via Receding-Horizon Dual Heuristic Programming.

PubMed

Lian, Chuanqiang; Xu, Xin; Chen, Hong; He, Haibo

2016-11-01

Trajectory tracking control of wheeled mobile robots (WMRs) has been an important research topic in control theory and robotics. Although various tracking control methods with stability have been developed for WMRs, it is still difficult to design optimal or near-optimal tracking controller under uncertainties and disturbances. In this paper, a near-optimal tracking control method is presented for WMRs based on receding-horizon dual heuristic programming (RHDHP). In the proposed method, a backstepping kinematic controller is designed to generate desired velocity profiles and the receding horizon strategy is used to decompose the infinite-horizon optimal control problem into a series of finite-horizon optimal control problems. In each horizon, a closed-loop tracking control policy is successively updated using a class of approximate dynamic programming algorithms called finite-horizon dual heuristic programming (DHP). The convergence property of the proposed method is analyzed and it is shown that the tracking control system based on RHDHP is asymptotically stable by using the Lyapunov approach. Simulation results on three tracking control problems demonstrate that the proposed method has improved control performance when compared with conventional model predictive control (MPC) and DHP. It is also illustrated that the proposed method has lower computational burden than conventional MPC, which is very beneficial for real-time tracking control.

Experimental verification of a real-time tuning method of a model-based controller by perturbations to its poles

NASA Astrophysics Data System (ADS)

Kajiwara, Itsuro; Furuya, Keiichiro; Ishizuka, Shinichi

2018-07-01

Model-based controllers with adaptive design variables are often used to control an object with time-dependent characteristics. However, the controller's performance is influenced by many factors such as modeling accuracy and fluctuations in the object's characteristics. One method to overcome these negative factors is to tune model-based controllers. Herein we propose an online tuning method to maintain control performance for an object that exhibits time-dependent variations. The proposed method employs the poles of the controller as design variables because the poles significantly impact performance. Specifically, we use the simultaneous perturbation stochastic approximation (SPSA) to optimize a model-based controller with multiple design variables. Moreover, a vibration control experiment of an object with time-dependent characteristics as the temperature is varied demonstrates that the proposed method allows adaptive control and stably maintains the closed-loop characteristics.

Neural network based automatic limit prediction and avoidance system and method

NASA Technical Reports Server (NTRS)

Calise, Anthony J. (Inventor); Prasad, Jonnalagadda V. R. (Inventor); Horn, Joseph F. (Inventor)

2001-01-01

A method for performance envelope boundary cueing for a vehicle control system comprises the steps of formulating a prediction system for a neural network and training the neural network to predict values of limited parameters as a function of current control positions and current vehicle operating conditions. The method further comprises the steps of applying the neural network to the control system of the vehicle, where the vehicle has capability for measuring current control positions and current vehicle operating conditions. The neural network generates a map of current control positions and vehicle operating conditions versus the limited parameters in a pre-determined vehicle operating condition. The method estimates critical control deflections from the current control positions required to drive the vehicle to a performance envelope boundary. Finally, the method comprises the steps of communicating the critical control deflection to the vehicle control system; and driving the vehicle control system to provide a tactile cue to an operator of the vehicle as the control positions approach the critical control deflections.

One shot methods for optimal control of distributed parameter systems 1: Finite dimensional control

NASA Technical Reports Server (NTRS)

Taasan, Shlomo

1991-01-01

The efficient numerical treatment of optimal control problems governed by elliptic partial differential equations (PDEs) and systems of elliptic PDEs, where the control is finite dimensional is discussed. Distributed control as well as boundary control cases are discussed. The main characteristic of the new methods is that they are designed to solve the full optimization problem directly, rather than accelerating a descent method by an efficient multigrid solver for the equations involved. The methods use the adjoint state in order to achieve efficient smoother and a robust coarsening strategy. The main idea is the treatment of the control variables on appropriate scales, i.e., control variables that correspond to smooth functions are solved for on coarse grids depending on the smoothness of these functions. Solution of the control problems is achieved with the cost of solving the constraint equations about two to three times (by a multigrid solver). Numerical examples demonstrate the effectiveness of the method proposed in distributed control case, pointwise control and boundary control problems.

Direct Optimal Control of Duffing Dynamics

NASA Technical Reports Server (NTRS)

Oz, Hayrani; Ramsey, John K.

2002-01-01

The "direct control method" is a novel concept that is an attractive alternative and competitor to the differential-equation-based methods. The direct method is equally well applicable to nonlinear, linear, time-varying, and time-invariant systems. For all such systems, the method yields explicit closed-form control laws based on minimization of a quadratic control performance measure. We present an application of the direct method to the dynamics and optimal control of the Duffing system where the control performance measure is not restricted to a quadratic form and hence may include a quartic energy term. The results we present in this report also constitute further generalizations of our earlier work in "direct optimal control methodology." The approach is demonstrated for the optimal control of the Duffing equation with a softening nonlinear stiffness.

Comparison of Control Group Generating Methods.

PubMed

Szekér, Szabolcs; Fogarassy, György; Vathy-Fogarassy, Ágnes

2017-01-01

Retrospective studies suffer from drawbacks such as selection bias. As the selection of the control group has a significant impact on the evaluation of the results, it is very important to find the proper method to generate the most appropriate control group. In this paper we suggest two nearest neighbors based control group selection methods that aim to achieve good matching between the individuals of case and control groups. The effectiveness of the proposed methods is evaluated by runtime and accuracy tests and the results are compared to the classical stratified sampling method.

IMPLICIT DUAL CONTROL BASED ON PARTICLE FILTERING AND FORWARD DYNAMIC PROGRAMMING.

PubMed

Bayard, David S; Schumitzky, Alan

2010-03-01

This paper develops a sampling-based approach to implicit dual control. Implicit dual control methods synthesize stochastic control policies by systematically approximating the stochastic dynamic programming equations of Bellman, in contrast to explicit dual control methods that artificially induce probing into the control law by modifying the cost function to include a term that rewards learning. The proposed implicit dual control approach is novel in that it combines a particle filter with a policy-iteration method for forward dynamic programming. The integration of the two methods provides a complete sampling-based approach to the problem. Implementation of the approach is simplified by making use of a specific architecture denoted as an H-block. Practical suggestions are given for reducing computational loads within the H-block for real-time applications. As an example, the method is applied to the control of a stochastic pendulum model having unknown mass, length, initial position and velocity, and unknown sign of its dc gain. Simulation results indicate that active controllers based on the described method can systematically improve closed-loop performance with respect to other more common stochastic control approaches.

A novel non-uniform control vector parameterization approach with time grid refinement for flight level tracking optimal control problems.

PubMed

Liu, Ping; Li, Guodong; Liu, Xinggao; Xiao, Long; Wang, Yalin; Yang, Chunhua; Gui, Weihua

2018-02-01

High quality control method is essential for the implementation of aircraft autopilot system. An optimal control problem model considering the safe aerodynamic envelop is therefore established to improve the control quality of aircraft flight level tracking. A novel non-uniform control vector parameterization (CVP) method with time grid refinement is then proposed for solving the optimal control problem. By introducing the Hilbert-Huang transform (HHT) analysis, an efficient time grid refinement approach is presented and an adaptive time grid is automatically obtained. With this refinement, the proposed method needs fewer optimization parameters to achieve better control quality when compared with uniform refinement CVP method, whereas the computational cost is lower. Two well-known flight level altitude tracking problems and one minimum time cost problem are tested as illustrations and the uniform refinement control vector parameterization method is adopted as the comparative base. Numerical results show that the proposed method achieves better performances in terms of optimization accuracy and computation cost; meanwhile, the control quality is efficiently improved. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Combined long-term caffeine intake and exercise inhibits the development of diabetic nephropathy in OLETF rats.

PubMed

Suzuki, Masato; Shindo, Daisuke; Suzuki, Ryuichiro; Shirataki, Yoshiaki; Waki, Hidefumi

2017-05-01

This study was performed to examine the effects of long-term caffeine-intake, with and without exercise, on the progression of diabetic nephropathy (DN) in an obese diabetic rat model. Thirty-two male Otsuka Long-Evans Tokushima fatty (OLETF) rats were assigned to sedentary (OLETF-Sed), exercise (OLETF-Ex), caffeine-intake (OLETF-Caf), and combined (OLETF-Caf + Ex) groups. Caffeine-intake groups were fed rat chow containing caffeine (90.7 ± 4.7 mg/kg/day). The OLETF-Ex and OLETF-Caf + Ex groups were able to run voluntarily at any time using a rotatory wheel. Body weight (BW) and blood pressure (BP) were measured weekly from 24 to 29 wk of age. Pre- and posttreatment serum glucose, insulin, and creatinine concentrations were measured, and a 24 h urine sample was collected for measurement of creatinine clearance (Ccr) and albumin excretion (UE Alb ). After treatment, the kidneys were removed for morphological analysis. The OLETF-Caf and OLETF-Caf + Ex groups exhibited no BP increase during the study. Both the caffeine-intake groups exhibited a significant increase in urine volume (UV), electrolyte excretion, and Ccr, and decreased UE Alb , following treatment. Furthermore, no structural damage was observed in the kidneys of rats from either caffeine-intake group, whereas the OLETF-Sed and OLETF-Ex groups exhibited DN progression. This study demonstrates that caffeine-intake alone and/or combined with exercise significantly decreases BW and improves glucose intolerance, without the progression of DN. Further research should be performed to examine whether the quantities of caffeine contained in a normal human daily intake also have a protective effect against kidney damage. NEW & NOTEWORTHY The present study showed that caffeine administration alone and/or combined with exercise results in an improvement of diabetic nephropathy (DN), including an increase in creatinine clearance and urinary Na excretion, a decrease in urinary protein excretion, and in renal morphological findings. To our knowledge, there are no other studies showing that caffeine administration inhibits DN progression. Copyright © 2017 the American Physiological Society.

Health-related quality of life in patients over sixty years old with benign paroxysmal positional vertigo.

PubMed

Gámiz, Maria J; Lopez-Escamez, Jose A

2004-01-01

Benign paroxysmal positional vertigo (BPPV) is a common cause of dizziness within the geriatric population causing disability. The diagnosis is established by the position-induced rotatory nystagmus, related to the involved ear, demonstrated by the Dix-Hallpike test (DHT). Although the Epley's modified manoeuvre, or particle respositioning manoeuvre (PRM), is an effective treatment for this disorder, its impact on health outcome in patients over 60 years old is unknown. To assess BPPV health-related quality of life in elderly individuals using the Medical Outcomes Study 36-Item Short Form Health Survey (SF-36) and the Dizziness Handicap Inventory Short Form (DHI-S). A prospective study including new cases of BPPV in patients older than 60 years was carried out. The diagnosis was based on the history of recurrent sudden crises of vertigo and a typical positional-induced nystagmus during the DHT. All patients were treated by a single PRM and relapses were investigated a the 30th post-treatment day. DHT was found negative in 82% (23/28) individuals at 30 days. The eight scales of the SF-36 have a good internal consistency reliability in patients with BPPV (Cronbach's alpha > 0.7). The average standardized score for each SF-36 scale was compared with the reference population normative data, showing differences with norms for role physical, body pain, social function, role emotional and mental health. After PRM, patients restored scores to norms, showing a significant increase in role physical (p < 0.05), body pain (p < 0.04), vitality (p < 0.02), social function (p < 0.003) and mental health scores (p < 0.005). DHI-S total score significantly decreased from 17.19 +/- 9.06 (mean +/- SD) at the first day to 9.70 +/- 10.13 at 30 days (p < 0.001). BPPV has a significant impact on health-related quality of life in elderly patients on their emotional and physical states compared to those unaffected. The PRM can restore health-related quality of life in elderly patients with BPPV. Copyright 2004 S. Karger AG, Basel

Vestibular evoked myogenic potentials and digital vectoelectro-nystagmography's study in patients with benign paroxysmal positional vertigo.

PubMed

Maria da Silva Lira-Batista, Marta; Schaffeln Dorigueto, Ricardo; Freitas Ganança, Cristina

2013-04-01

 Benign Paroxysmal Positional Vertigo (BPPV) is a very common vestibular disorder characterized by brief but intense attacks of rotatory vertigo triggered by simple rapid movement of the head. The integrity of the vestibular pathways can be assessed using tests such as digital vectoelectronystagmography (VENG) and vestibular evoked myogenic potentials (VEMP).  This study aimed to determine the VEMP findings with respect to latency, amplitude, and waveform peak to peak and the results of the oculomotor and vestibular components of VENG in patients with BPPV.  Although this otoneurological condition is quite common, little is known of the associated VEMP and VENG changes, making it important to research and describe these results.  We examined the records of 4438 patients and selected 35 charts after applying the inclusion and exclusion criteria. Of these, 26 patients were women and 9 men. The average age at diagnosis was 52.7 years, and the most prevalent physiological cause, accounting for 97.3% of cases, was ductolithiasis. There was a statistically significant association between normal hearing and mild contralateral sensorineural hearing loss. The results of the oculomotor tests were within the normal reference ranges for all subjects. Patients with BPPV exhibited symmetrical function of the semicircular canals in their synergistic pairs (p < 0.001). The caloric test showed statistically normal responses from the lateral canals. The waveforms of all patients were adequate, but the VEMP results for the data-crossing maneuver with positive positioning showed a trend toward a relationship for the left ear Lp13. There was also a trend towards an association between normal reflexes in the caloric test and the inter-peak VEMP of the left ear. It can be concluded that although there are some differences between the average levels of the VENG and VEMP results, these differences were not statistically significant.  In conclusion, the results of audiologic assessment, hearing thresholds, positioning maneuvers, and caloric tests have no effect on the quantitative results of VEMP. Additional research is warranted to establish the relationships among VENG, VEMP, and BPPV, especially as concerns the oculomotor tests.

Rater agreement reliability of the dial test in the ACL-deficient knee.

PubMed

Slichter, Malou E; Wolterbeek, Nienke; Auw Yang, K Gie; Zijl, Jacco A C; Piscaer, Tom M

2018-06-14

Posterolateral rotatory instability (PLRI) of the knee can easily be missed, because attention is paid to injury of the cruciate ligaments. If left untreated this clinical instability may persist after reconstruction of the cruciate ligaments and may put the graft at risk of failure. Even though the dial test is widely used to diagnose PLRI, no validity and reliability studies of the manual dial test are yet performed in patients. This study focuses on the reliability of the manual dial test by determining the rater agreement. Two independent examiners performed the dial test in knees of 52 patients after knee distorsion with a suspicion on ACL rupture. The dial test was performed in prone position in 30°, 60° and 90° of flexion of the knees. ≥10° side-to-side difference was considered a positive dial test. For quantification of the amount of rotation in degrees, a measuring device was used with a standardized 6 Nm force, using a digital torque adapter on a booth. The intra-rater, inter-rater and rater-device agreement were determined by calculating kappa (κ) for the dial test. A positive dial test was found in 21.2% and 18.0% of the patients as assessed by a blinded examiner and orthopaedic surgeon respectively. Fair inter-rater agreement was found in 30° of flexion, κ F  = 0.29 (95% CI: 0.01 to 0.56), p = 0.044 and 90° of flexion, κ F  = 0.38 (95% CI: 0.10 to 0.66), p = 0.007. Almost perfect rater-device agreement was found in 30° of flexion, κ C  = 0.84 (95% CI: 0.52 to 1.15), p < 0.001. Moderate rater-device agreement was found in 30° and 90° combined, κ C  = 0.50 (95% CI: 0.13 to 0.86), p = 0.008. No significant intra-rater agreement was found. Rater agreement reliability of the manual dial test is questionable. It has a fair inter-rater agreement in 30° and 90° of flexion.

The effects of the use of piezoelectric motors in a 1.5-Tesla high-field magnetic resonance imaging system (MRI).

PubMed

Wendt, O; Oellinger, J; Lüth, T C; Felix, R; Boenick, U

2000-01-01

This paper presents the results of an experimental investigation with two different rotatory piezomotors in a closed 1.5 Tesla high-field MRI. The focus of the investigation was on testing the functionality of these motors within the MRI and to determining the image interference they caused. To obtain a differentiated estimate of the interference the motors were tested in both the passive (turned off, i.e. without current flow) and active (turned on, i.e. with current flow) state during MRI scanning. Three different types of sequences were used for the test: Spin-Echo (SE), Gradient-Echo (GE) and Echo-Planar Imaging (EPI). A plastic container filled with a gadolinium-manganese solution was used for representation of the artefacts. The motors investigated were placed parallel to the container at predetermined distances during the experiment. The results show that the motors investigated suffered no functional limitations in the magnetic field of the MRI but, depending on the type of motor, the measurement distance and the state of the motor, the motors had different effects on the sequence images. A motor in the off-state placed immediately next to the object to be measured mainly causes artefacts because of its material properties. If, on the other hand, the piezomotor is in the on-state images with strong noise result when the motor is immediately next to the object being measured. The images regain their normal quality when the motor is approximately at a distance of 1 m from the object being investigated. Driving the motor inside the MRI, therefore, is only to be recommended during the pauses in scanning: this delivers artefact-free images if minimal, motor-specific distances are kept to. With regard to the three different types of sequences it was determined that the SE sequence was the least sensitive and the EPI sequence the most sensitive to disturbance. The GE sequence showed only minimal differences to the SE sequence with regard to signal-to-noise ratios. Since it requires considerably shorter scan-times it can be considered to be the most effective type of sequence under these conditions.

Interaction of a chick skin collagen fragment (alpha1-CB5) with human platelets. Biochemical studies during the aggregation and release reaction.

PubMed

Chiang, T M; Beachey, E H; Kang, A H

1975-09-10

The denatured alpha1(I) chain and the cyanogen bromide peptide, alpha1(I)-CB5, of chick skin collagen cause the release of serotonin and leakage of lactic dehydrogenase from human platelets in a manner similar to the release reaction mediated by adenosine diphosphate and native collagen. These peptides also cause a decrease in the level of adenosine 3':5'-monophosphate (cAMP) in platelets. Adenylate cyclase activity of platelets is partially inhibited by these peptides as well as by native collagen, ADP, and epinephrine, but cAMP phosphodiesterase activity is unaltered by these substances. In contrast, the level of platelet guanosine 3':5'-monophosphate (cGMP) is increased by the collagen peptides as well as the other aggregating agents. The increase is associated with increased guanylate cyclase, but normal cGMP phosphodiesterase activities of platelets. Optical rotatory and viscometric measurements of the alpha1 chains and alpha1-CB5 of chick skin in 0.01 M phosphate/0.15 M sodium chloride, pH 7.4, at various temperatures as a function of time indicate that no detectable renaturation occurs at 37 degrees for at least 30 min of observation. Molecular sieve chromatography of alpha1-CB5 in the phosphate buffer at 37 degrees shows that its elution position is identical to that performed under denaturing conditions (at 45 degrees) with no evidence of higher molecular weight aggregates, and the alpha1-CB5 glycopeptide fraction eluting from the column at the position of its monomer retains the platelet aggregating activity. Additionally, electron microscopic examination of the platelet-rich plasma that had been reacted with these peptides fail to show any ordered collagen structures. These data indicate that the denatured alpha1 chain and alpha1-CB5 glycopeptide of chick skin collagen mediate platelet aggregation through the "physiologic" release reaction in a manner similar to that induced by other aggregating agents such as ADP, epinephrine, or native collagen, and support the conclusion that the aggregating activity of the alpha1 chain and alpha1-CB5 is not likely to be due to the formation of polymerized products.

Change of temporal-order judgment of sounds during long-lasting exposure to large-field visual motion.

PubMed

Teramoto, Wataru; Watanabe, Hiroshi; Umemura, Hiroyuki

2008-01-01

The perceived temporal order of external successive events does not always follow their physical temporal order. We examined the contribution of self-motion mechanisms in the perception of temporal order in the auditory modality. We measured perceptual biases in the judgment of the temporal order of two short sounds presented successively, while participants experienced visually induced self-motion (yaw-axis circular vection) elicited by viewing long-lasting large-field visual motion. In experiment 1, a pair of white-noise patterns was presented to participants at various stimulus-onset asynchronies through headphones, while they experienced visually induced self-motion. Perceived temporal order of auditory events was modulated by the direction of the visual motion (or self-motion). Specifically, the sound presented to the ear in the direction opposite to the visual motion (ie heading direction) was perceived prior to the sound presented to the ear in the same direction. Experiments 2A and 2B were designed to reduce the contributions of decisional and/or response processes. In experiment 2A, the directional cueing of the background (left or right) and the response dimension (high pitch or low pitch) were not spatially associated. In experiment 2B, participants were additionally asked to report which of the two sounds was perceived 'second'. Almost the same results as in experiment 1 were observed, suggesting that the change in temporal order of auditory events during large-field visual motion reflects a change in perceptual processing. Experiment 3 showed that the biases in the temporal-order judgments of auditory events were caused by concurrent actual self-motion with a rotatory chair. In experiment 4, using a small display, we showed that 'pure' long exposure to visual motion without the sensation of self-motion was not responsible for this phenomenon. These results are consistent with previous studies reporting a change in the perceived temporal order of visual or tactile events depending on the direction of self-motion. Hence, large-field induced (ie optic flow) self-motion can affect the temporal order of successive external events across various modalities.

Longitudinal control of aircraft dynamics based on optimization of PID parameters

NASA Astrophysics Data System (ADS)

Deepa, S. N.; Sudha, G.

2016-03-01

Recent years many flight control systems and industries are employing PID controllers to improve the dynamic behavior of the characteristics. In this paper, PID controller is developed to improve the stability and performance of general aviation aircraft system. Designing the optimum PID controller parameters for a pitch control aircraft is important in expanding the flight safety envelope. Mathematical model is developed to describe the longitudinal pitch control of an aircraft. The PID controller is designed based on the dynamic modeling of an aircraft system. Different tuning methods namely Zeigler-Nichols method (ZN), Modified Zeigler-Nichols method, Tyreus-Luyben tuning, Astrom-Hagglund tuning methods are employed. The time domain specifications of different tuning methods are compared to obtain the optimum parameters value. The results prove that PID controller tuned by Zeigler-Nichols for aircraft pitch control dynamics is better in stability and performance in all conditions. Future research work of obtaining optimum PID controller parameters using artificial intelligence techniques should be carried out.

An In Vitro Robotic Assessment of the Anterolateral Ligament, Part 1: Secondary Role of the Anterolateral Ligament in the Setting of an Anterior Cruciate Ligament Injury.

PubMed

Rasmussen, Matthew T; Nitri, Marco; Williams, Brady T; Moulton, Samuel G; Cruz, Raphael Serra; Dornan, Grant J; Goldsmith, Mary T; LaPrade, Robert F

2016-03-01

Recent investigations have described the structural and functional behavior of the anterolateral ligament (ALL) of the knee through pull-apart and isolated sectioning studies. However, the secondary stabilizing role of the ALL in the setting of a complete anterior cruciate ligament (ACL) tear has not been fully defined for common simulated clinical examinations, such as the pivot-shift, anterior drawer, and internal rotation tests. Combined sectioning of the ALL and ACL would lead to increased internal rotation and increased axial plane translation during a pivot-shift test when compared with isolated sectioning of the ACL. Controlled laboratory study. Ten fresh-frozen human cadaveric knees were subjected to a simulated pivot-shift test with coupled 10-N·m valgus and 5-N·m internal rotation torques from 0° to 60° of knee flexion and a 5-N·m internal rotation torque and an 88-N anterior tibial load, both from 0° to 120° of knee flexion via a 6 degrees of freedom robotic system. Kinematic changes were measured and compared with the intact state for isolated sectioning of the ACL and combined sectioning of the ACL and ALL. Combined sectioning of the ACL and ALL resulted in a significant increase in axial plane tibial translation during a simulated pivot shift at 0°, 15°, 30°, and 60° of knee flexion and a significant increase in internal rotation at 0°, 15°, 30°, 45°, 60°, 75°, 90°, 105°, and 120° when compared with the intact and ACL-deficient states. Based on the model results, ALL sectioning resulted in an additional 2.1 mm (95% CI, 1.4-2.9 mm; P < .001) of axial plane translation during the pivot shift when compared with ACL-only sectioning, when pooling evidence over all flexion angles. Likewise, when subjected to IR torque, the ACL+ALL-deficient state resulted in an additional 3.2° of internal rotation (95% CI, 2.4°-4.1°; P < .001) versus the intact state, and the additional sectioning of the ALL increased internal rotation by 2.7° (95% CI, 1.8°-3.6°; P < .001) versus the ACL-deficient state. The results of this study confirm the ALL as an important lateral knee structure that provides rotatory stability to the knee. Specifically, the ALL was a significant secondary stabilizer throughout flexion during an applied internal rotation torque and simulated pivot-shift test in the context of an ACL-deficient knee. Residual internal rotation and a positive pivot shift after ACL reconstruction may be attributed to ALL injury. For these patients, surgical treatment of an ALL tear may be considered. © 2015 The Author(s).

A comparison between IMSC, PI and MIMSC methods in controlling the vibration of flexible systems

NASA Technical Reports Server (NTRS)

Baz, A.; Poh, S.

1987-01-01

A comparative study is presented between three active control algorithms which have proven to be successful in controlling the vibrations of large flexible systems. These algorithms are: the Independent Modal Space Control (IMSC), the Pseudo-inverse (PI), and the Modified Independent Modal Space Control (MIMSC). Emphasis is placed on demonstrating the effectiveness of the MIMSC method in controlling the vibration of large systems with small number of actuators by using an efficient time sharing strategy. Such a strategy favors the MIMSC over the IMSC method, which requires a large number of actuators to control equal number of modes, and also over the PI method which attempts to control large number of modes with smaller number of actuators through the use of an in-exact statistical realization of a modal controller. Numerical examples are presented to illustrate the main features of the three algorithms and the merits of the MIMSC method.

Three different methods for the derivation of control laws for multi-degree-of-freedom systems containing electrorheological dampers

NASA Astrophysics Data System (ADS)

Moosheimer, Johannes; Waller, Heinz

1999-06-01

The minimization of unwanted vibrations is an important technical challenge. Purely passive systems often do not achieve the postulated results. Purely active systems are costly because of the required additional power and the necessary maintenance. Currently it seems that semi-active methods of vibration reduction are as competitive as any other methods. Semi-active damping control can be realized with electro- or magnetorheological fluids. These change their characteristic in the presence of an electric or magnetic field or by bypasses combined with magnetic valves. The methods known in linear control theory cannot be used for the controller design because no explicit external forces can be generated whenever they are needed. Forces can only be generated when relative velocities between the endpoints of the damper exist. It is important to investigate control methods which will reduce vibration with controlled damping. In this paper three different methods for establishing control laws are presented. The first is based on the consideration of power flow in the system. It is discussed in detail. The second method uses Bellmans dynamic optimization. The last transforms a multi degree of freedom system by modal analysis into uncoupled single degree of freedom systems. The control methods developed by these three methods all lead to the same vibration reduction strategy. The control laws are verified with simulation results.

Women and postfertilization effects of birth control: consistency of beliefs, intentions and reported use.

PubMed

Dye, Huong M; Stanford, Joseph B; Alder, Stephen C; Kim, Han S; Murphy, Patricia A

2005-11-28

This study assesses the consistency of responses among women regarding their beliefs about the mechanisms of actions of birth control methods, beliefs about when human life begins, the intention to use or not use birth control methods that they believe may act after fertilization or implantation, and their reported use of specific methods. A questionnaire was administered in family practice and obstetrics and gynecology clinics in Salt Lake City, Utah, and Tulsa, Oklahoma. Participants included women ages 18-50 presenting for any reason and women under age 18 presenting for family planning or pregnancy care. Analyses were based on key questions addressing beliefs about whether specific birth control methods may act after fertilization, beliefs about when human life begins, intention to use a method that may act after fertilization, and reported use of specific methods. The questionnaire contained no information about the mechanism of action of any method of birth control. Responses were considered inconsistent if actual use contradicted intentions, if one intention contradicted another, or if intentions contradicted beliefs. Of all respondents, 38% gave consistent responses about intention to not use or to stop use of any birth control method that acted after fertilization, while 4% gave inconsistent responses. The corresponding percentages for birth control methods that work after implantation were 64% consistent and 2% inconsistent. Of all respondents, 34% reported they believed that life begins at fertilization and would not use any birth control method that acts after fertilization (a consistent response), while 3% reported they believed that life begins at fertilization but would use a birth control method that acts after fertilization (inconsistent). For specific methods of birth control, less than 1% of women gave inconsistent responses. A majority of women (68% or greater) responded accurately about the mechanism of action of condoms, abstinence, sterilization, and abortion, but a substantial percentage of women (between 19% and 57%) were uncertain about the mechanisms of action of oral contraceptives, intrauterine devices (IUDs), Depo-Provera, or natural family planning. Women who believe that life begins at fertilization may not intend to use a birth control method that could have postfertilization effects. More research is needed to understand the relative importance of postfertilization effects for women in other populations, and in relation to other properties of and priorities for birth control methods. However, many women were uncertain about the mechanisms of action of specific methods. To respect the principles of informed consent, some women may need more education about what is known and not known about the mechanisms of action of birth control methods.

An Optimal Control Method for Maximizing the Efficiency of Direct Drive Ocean Wave Energy Extraction System

PubMed Central

Chen, Zhongxian; Yu, Haitao; Wen, Cheng

2014-01-01

The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID) is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the heavy speed of outer heavy buoy of the energy extraction system is in resonance with incident wave, and the system efficiency is largely improved. Validity of the proposed optimal control method is verified in both regular and irregular ocean waves, and it is shown that IM-PID control method is optimal in that it maximizes the energy conversion efficiency. In addition, the anti-interference ability of IM-PID control method has been assessed, and the results show that the IM-PID control method has good robustness, high precision, and strong anti-interference ability. PMID:25152913

An optimal control method for maximizing the efficiency of direct drive ocean wave energy extraction system.

PubMed

Chen, Zhongxian; Yu, Haitao; Wen, Cheng

2014-01-01

The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID) is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the heavy speed of outer heavy buoy of the energy extraction system is in resonance with incident wave, and the system efficiency is largely improved. Validity of the proposed optimal control method is verified in both regular and irregular ocean waves, and it is shown that IM-PID control method is optimal in that it maximizes the energy conversion efficiency. In addition, the anti-interference ability of IM-PID control method has been assessed, and the results show that the IM-PID control method has good robustness, high precision, and strong anti-interference ability.

Control mechanism of double-rotator-structure ternary optical computer

NASA Astrophysics Data System (ADS)

Kai, SONG; Liping, YAN

2017-03-01

Double-rotator-structure ternary optical processor (DRSTOP) has two characteristics, namely, giant data-bits parallel computing and reconfigurable processor, which can handle thousands of data bits in parallel, and can run much faster than computers and other optical computer systems so far. In order to put DRSTOP into practical application, this paper established a series of methods, namely, task classification method, data-bits allocation method, control information generation method, control information formatting and sending method, and decoded results obtaining method and so on. These methods form the control mechanism of DRSTOP. This control mechanism makes DRSTOP become an automated computing platform. Compared with the traditional calculation tools, DRSTOP computing platform can ease the contradiction between high energy consumption and big data computing due to greatly reducing the cost of communications and I/O. Finally, the paper designed a set of experiments for DRSTOP control mechanism to verify its feasibility and correctness. Experimental results showed that the control mechanism is correct, feasible and efficient.

Feedback control for unsteady flow and its application to the stochastic Burgers equation

NASA Technical Reports Server (NTRS)

Choi, Haecheon; Temam, Roger; Moin, Parviz; Kim, John

1993-01-01

The study applies mathematical methods of control theory to the problem of control of fluid flow with the long-range objective of developing effective methods for the control of turbulent flows. Model problems are employed through the formalism and language of control theory to present the procedure of how to cast the problem of controlling turbulence into a problem in optimal control theory. Methods of calculus of variations through the adjoint state and gradient algorithms are used to present a suboptimal control and feedback procedure for stationary and time-dependent problems. Two types of controls are investigated: distributed and boundary controls. Several cases of both controls are numerically simulated to investigate the performances of the control algorithm. Most cases considered show significant reductions of the costs to be minimized. The dependence of the control algorithm on the time-descretization method is discussed.

Trajectory control method of stratospheric airship based on the sliding mode control and prediction in wind field

NASA Astrophysics Data System (ADS)

Zhang, Jia-shi; Yang, Xi-xiang

2017-11-01

The stratospheric airship has the characteristics of large inertia, long time delay and large disturbance of wind field , so the trajectory control is very difficult .Build the lateral three degrees of freedom dynamic model which consider the wind interference , the dynamics equation is linearized by the small perturbation theory, propose a trajectory control method Combine with the sliding mode control and prediction, design the trajectory controller , takes the HAA airship as the reference to carry out simulation analysis. Results show that the improved sliding mode control with front-feedback method not only can solve well control problems of airship trajectory in wind field, but also can effectively improve the control accuracy of the traditional sliding mode control method, solved problems that using the traditional sliding mode control to control. It provides a useful reference for dynamic modeling and trajectory control of stratospheric airship.

Planting pattern and weed control method influence on yield production of corn (Zea mays L.)

NASA Astrophysics Data System (ADS)

Purba, E.; Nasution, D. P.

2018-02-01

Field experiment was carried out to evaluate the influence of planting patterns and weed control methods on the growth and yield of corn. The effect of the planting pattern and weed control method was studied in a split plot design. The main plots were that of planting pattern single row (25cm x 60cm), double row (25cm x 25cm x 60cm) and triangle row ( 25cm x 25cm x 25cm). Subplot was that of weed control method consisted five methods namely weed free throughout the growing season, hand weeding, sprayed with glyphosate, sprayed with paraquat, and no weeding.. Result showed that both planting pattern and weed control method did not affect the growth of corn. However, planting pattern and weed control method significantly affected yield production. Yield resulted from double row and triangle planting pattern was 14% and 41% higher, consecutively, than that of single row pattern. The triangle planting pattern combined with any weed control method produced the highest yield production of corn.

Control methods and systems for indirect evaporative coolers

DOEpatents

Woods, Jason; Kozubal, Erik

2015-09-22

A control method for operating an indirect evaporative cooler to control temperature and humidity. The method includes operating an airflow control device to provide supply air at a flow rate to a liquid desiccant dehumidifier. The supply air flows through the dehumidifier and an indirect evaporative cooler prior to exiting an outlet into a space. The method includes operating a pump to provide liquid desiccant to the liquid desiccant dehumidifier and sensing a temperature of an airstream at the outlet of the indirect evaporative cooler. The method includes comparing the temperature of the airstream at the outlet to a setpoint temperature at the outlet and controlling the pump to set the flow rate of the liquid desiccant. The method includes sensing space temperature, comparing the space temperature with a setpoint temperature, and controlling the airflow control device to set the flow rate of the supply air based on the comparison.

Design and experimental validation of linear and nonlinear vehicle steering control strategies

NASA Astrophysics Data System (ADS)

Menhour, Lghani; Lechner, Daniel; Charara, Ali

2012-06-01

This paper proposes the design of three control laws dedicated to vehicle steering control, two based on robust linear control strategies and one based on nonlinear control strategies, and presents a comparison between them. The two robust linear control laws (indirect and direct methods) are built around M linear bicycle models, each of these control laws is composed of two M proportional integral derivative (PID) controllers: one M PID controller to control the lateral deviation and the other M PID controller to control the vehicle yaw angle. The indirect control law method is designed using an oscillation method and a nonlinear optimisation subject to H ∞ constraint. The direct control law method is designed using a linear matrix inequality optimisation in order to achieve H ∞ performances. The nonlinear control method used for the correction of the lateral deviation is based on a continuous first-order sliding-mode controller. The different methods are designed using a linear bicycle vehicle model with variant parameters, but the aim is to simulate the nonlinear vehicle behaviour under high dynamic demands with a four-wheel vehicle model. These steering vehicle controls are validated experimentally using the data acquired using a laboratory vehicle, Peugeot 307, developed by National Institute for Transport and Safety Research - Department of Accident Mechanism Analysis Laboratory's (INRETS-MA) and their performance results are compared. Moreover, an unknown input sliding-mode observer is introduced to estimate the road bank angle.

Direct SQP-methods for solving optimal control problems with delays

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

Goellmann, L.; Bueskens, C.; Maurer, H.

The maximum principle for optimal control problems with delays leads to a boundary value problem (BVP) which is retarded in the state and advanced in the costate function. Based on shooting techniques, solution methods for this type of BVP have been proposed. In recent years, direct optimization methods have been favored for solving control problems without delays. Direct methods approximate the control and the state over a fixed mesh and solve the resulting NLP-problem with SQP-methods. These methods dispense with the costate function and have shown to be robust and efficient. In this paper, we propose a direct SQP-method formore » retarded control problems. In contrast to conventional direct methods, only the control variable is approximated by e.g. spline-functions. The state is computed via a high order Runge-Kutta type algorithm and does not enter explicitly the NLP-problem through an equation. This approach reduces the number of optimization variables considerably and is implementable even on a PC. Our method is illustrated by the numerical solution of retarded control problems with constraints. In particular, we consider the control of a continuous stirred tank reactor which has been solved by dynamic programming. This example illustrates the robustness and efficiency of the proposed method. Open questions concerning sufficient conditions and convergence of discretized NLP-problems are discussed.« less

Method and apparatus for in-system redundant array repair on integrated circuits

DOEpatents

Bright, Arthur A [Croton-on-Hudson, NY; Crumley, Paul G [Yorktown Heights, NY; Dombrowa, Marc B [Bronx, NY; Douskey, Steven M [Rochester, MN; Haring, Rudolf A [Cortlandt Manor, NY; Oakland, Steven F [Colchester, VT; Ouellette, Michael R [Westford, VT; Strissel, Scott A [Byron, MN

2008-07-29

Disclosed is a method of repairing an integrated circuit of the type comprising of a multitude of memory arrays and a fuse box holding control data for controlling redundancy logic of the arrays. The method comprises the steps of providing the integrated circuit with a control data selector for passing the control data from the fuse box to the memory arrays; providing a source of alternate control data, external of the integrated circuit; and connecting the source of alternate control data to the control data selector. The method comprises the further step of, at a given time, passing the alternate control data from the source thereof, through the control data selector and to the memory arrays to control the redundancy logic of the memory arrays.

Method and apparatus for in-system redundant array repair on integrated circuits

DOEpatents

Bright, Arthur A [Croton-on-Hudson, NY; Crumley, Paul G [Yorktown Heights, NY; Dombrowa, Marc B [Bronx, NY; Douskey, Steven M [Rochester, MN; Haring, Rudolf A [Cortlandt Manor, NY; Oakland, Steven F [Colchester, VT; Ouellette, Michael R [Westford, VT; Strissel, Scott A [Byron, MN

2008-07-08

Disclosed is a method of repairing an integrated circuit of the type comprising of a multitude of memory arrays and a fuse box holding control data for controlling redundancy logic of the arrays. The method comprises the steps of providing the integrated circuit with a control data selector for passing the control data from the fuse box to the memory arrays; providing a source of alternate control data, external of the integrated circuit; and connecting the source of alternate control data to the control data selector. The method comprises the further step of, at a given time, passing the alternate control data from the source thereof, through the control data selector and to the memory arrays to control the redundancy logic of the memory arrays.

Method and apparatus for in-system redundant array repair on integrated circuits

DOEpatents

Bright, Arthur A.; Crumley, Paul G.; Dombrowa, Marc B.; Douskey, Steven M.; Haring, Rudolf A.; Oakland, Steven F.; Ouellette, Michael R.; Strissel, Scott A.

2007-12-18

Disclosed is a method of repairing an integrated circuit of the type comprising of a multitude of memory arrays and a fuse box holding control data for controlling redundancy logic of the arrays. The method comprises the steps of providing the integrated circuit with a control data selector for passing the control data from the fuse box to the memory arrays; providing a source of alternate control data, external of the integrated circuit; and connecting the source of alternate control data to the control data selector. The method comprises the further step of, at a given time, passing the alternate control data from the source thereof, through the control data selector and to the memory arrays to control the redundancy logic of the memory arrays.

Attitude and vibration control of a large flexible space-based antenna

NASA Technical Reports Server (NTRS)

Joshi, S. M.

1982-01-01

Control systems synthesis is considered for controlling the rigid body attitude and elastic motion of a large deployable space-based antenna. Two methods for control systems synthesis are considered. The first method utilizes the stability and robustness properties of the controller consisting of torque actuators and collocated attitude and rate sensors. The second method is based on the linear-quadratic-Gaussian control theory. A combination of the two methods, which results in a two level hierarchical control system, is also briefly discussed. The performance of the controllers is analyzed by computing the variances of pointing errors, feed misalignment errors and surface contour errors in the presence of sensor and actuator noise.

Systems and Methods for Parameter Dependent Riccati Equation Approaches to Adaptive Control

NASA Technical Reports Server (NTRS)

Kim, Kilsoo (Inventor); Yucelen, Tansel (Inventor); Calise, Anthony J. (Inventor)

2015-01-01

Systems and methods for adaptive control are disclosed. The systems and methods can control uncertain dynamic systems. The control system can comprise a controller that employs a parameter dependent Riccati equation. The controller can produce a response that causes the state of the system to remain bounded. The control system can control both minimum phase and non-minimum phase systems. The control system can augment an existing, non-adaptive control design without modifying the gains employed in that design. The control system can also avoid the use of high gains in both the observer design and the adaptive control law.

Controller design via structural reduced modeling by FETM

NASA Technical Reports Server (NTRS)

Yousuff, Ajmal

1987-01-01

The Finite Element-Transfer Matrix (FETM) method has been developed to reduce the computations involved in analysis of structures. This widely accepted method, however, has certain limitations, and does not address the issues of control design. To overcome these, a modification of the FETM method has been developed. The new method easily produces reduced models tailored toward subsequent control design. Other features of this method are its ability to: (1) extract open loop frequencies and mode shapes with less computations, (2) overcome limitations of the original FETM method, and (3) simplify the design procedures for output feedback, constrained compensation, and decentralized control. This report presents the development of the new method, generation of reduced models by this method, their properties, and the role of these reduced models in control design. Examples are included to illustrate the methodology.

Investigation of the Multiple Method Adaptive Control (MMAC) method for flight control systems

NASA Technical Reports Server (NTRS)

Athans, M.; Baram, Y.; Castanon, D.; Dunn, K. P.; Green, C. S.; Lee, W. H.; Sandell, N. R., Jr.; Willsky, A. S.

1979-01-01

The stochastic adaptive control of the NASA F-8C digital-fly-by-wire aircraft using the multiple model adaptive control (MMAC) method is presented. The selection of the performance criteria for the lateral and the longitudinal dynamics, the design of the Kalman filters for different operating conditions, the identification algorithm associated with the MMAC method, the control system design, and simulation results obtained using the real time simulator of the F-8 aircraft at the NASA Langley Research Center are discussed.

Parametric synthesis of a robust controller on a base of mathematical programming method

NASA Astrophysics Data System (ADS)

Khozhaev, I. V.; Gayvoronskiy, S. A.; Ezangina, T. A.

2018-05-01

Considered paper is dedicated to deriving sufficient conditions, linking root indices of robust control quality with coefficients of interval characteristic polynomial, on the base of mathematical programming method. On the base of these conditions, a method of PI- and PID-controllers, providing aperiodic transient process with acceptable stability degree and, subsequently, acceptable setting time, synthesis was developed. The method was applied to a problem of synthesizing a controller for a depth control system of an unmanned underwater vehicle.

Investigating Item Exposure Control Methods in Computerized Adaptive Testing

ERIC Educational Resources Information Center

Ozturk, Nagihan Boztunc; Dogan, Nuri

2015-01-01

This study aims to investigate the effects of item exposure control methods on measurement precision and on test security under various item selection methods and item pool characteristics. In this study, the Randomesque (with item group sizes of 5 and 10), Sympson-Hetter, and Fade-Away methods were used as item exposure control methods. Moreover,…

Women and postfertilization effects of birth control: consistency of beliefs, intentions and reported use

PubMed Central

Dye, Huong M; Stanford, Joseph B; Alder, Stephen C; Kim, Han S; Murphy, Patricia A

2005-01-01

Background This study assesses the consistency of responses among women regarding their beliefs about the mechanisms of actions of birth control methods, beliefs about when human life begins, the intention to use or not use birth control methods that they believe may act after fertilization or implantation, and their reported use of specific methods. Methods A questionnaire was administered in family practice and obstetrics and gynecology clinics in Salt Lake City, Utah, and Tulsa, Oklahoma. Participants included women ages 18–50 presenting for any reason and women under age 18 presenting for family planning or pregnancy care. Analyses were based on key questions addressing beliefs about whether specific birth control methods may act after fertilization, beliefs about when human life begins, intention to use a method that may act after fertilization, and reported use of specific methods. The questionnaire contained no information about the mechanism of action of any method of birth control. Responses were considered inconsistent if actual use contradicted intentions, if one intention contradicted another, or if intentions contradicted beliefs. Results Of all respondents, 38% gave consistent responses about intention to not use or to stop use of any birth control method that acted after fertilization, while 4% gave inconsistent responses. The corresponding percentages for birth control methods that work after implantation were 64% consistent and 2% inconsistent. Of all respondents, 34% reported they believed that life begins at fertilization and would not use any birth control method that acts after fertilization (a consistent response), while 3% reported they believed that life begins at fertilization but would use a birth control method that acts after fertilization (inconsistent). For specific methods of birth control, less than 1% of women gave inconsistent responses. A majority of women (68% or greater) responded accurately about the mechanism of action of condoms, abstinence, sterilization, and abortion, but a substantial percentage of women (between 19% and 57%) were uncertain about the mechanisms of action of oral contraceptives, intrauterine devices (IUDs), Depo-Provera, or natural family planning. Conclusion Women who believe that life begins at fertilization may not intend to use a birth control method that could have postfertilization effects. More research is needed to understand the relative importance of postfertilization effects for women in other populations, and in relation to other properties of and priorities for birth control methods. However, many women were uncertain about the mechanisms of action of specific methods. To respect the principles of informed consent, some women may need more education about what is known and not known about the mechanisms of action of birth control methods. PMID:16313677

Summary of Fluidic Thrust Vectoring Research Conducted at NASA Langley Research Center

NASA Technical Reports Server (NTRS)

Deere, Karen A.

2003-01-01

Interest in low-observable aircraft and in lowering an aircraft's exhaust system weight sparked decades of research for fixed geometry exhaust nozzles. The desire for such integrated exhaust nozzles was the catalyst for new fluidic control techniques; including throat area control, expansion control, and thrust-vector angle control. This paper summarizes a variety of fluidic thrust vectoring concepts that have been tested both experimentally and computationally at NASA Langley Research Center. The nozzle concepts are divided into three categories according to the method used for fluidic thrust vectoring: the shock vector control method, the throat shifting method, and the counterflow method. This paper explains the thrust vectoring mechanism for each fluidic method, provides examples of configurations tested for each method, and discusses the advantages and disadvantages of each method.

An Adaptive Instability Suppression Controls Method for Aircraft Gas Turbine Engine Combustors

NASA Technical Reports Server (NTRS)

Kopasakis, George; DeLaat, John C.; Chang, Clarence T.

2008-01-01

An adaptive controls method for instability suppression in gas turbine engine combustors has been developed and successfully tested with a realistic aircraft engine combustor rig. This testing was part of a program that demonstrated, for the first time, successful active combustor instability control in an aircraft gas turbine engine-like environment. The controls method is called Adaptive Sliding Phasor Averaged Control. Testing of the control method has been conducted in an experimental rig with different configurations designed to simulate combustors with instabilities of about 530 and 315 Hz. Results demonstrate the effectiveness of this method in suppressing combustor instabilities. In addition, a dramatic improvement in suppression of the instability was achieved by focusing control on the second harmonic of the instability. This is believed to be due to a phenomena discovered and reported earlier, the so called Intra-Harmonic Coupling. These results may have implications for future research in combustor instability control.

Real-time cartesian force feedback control of a teleoperated robot

NASA Technical Reports Server (NTRS)

Campbell, Perry

1989-01-01

Active cartesian force control of a teleoperated robot is investigated. An economical microcomputer based control method was tested. Limitations are discussed and methods of performance improvement suggested. To demonstrate the performance of this technique, a preliminary test was performed with success. A general purpose bilateral force reflecting hand controller is currently being constructed based on this control method.

Condom

MedlinePlus

... couples use condoms along with another method of birth control, like birth control pills or an IUD . For condoms to have ... against STDs even when using another method of birth control. Abstinence (not having sex) is the only method ...

Integrated structural control design of large space structures

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

Allen, J.J.; Lauffer, J.P.

1995-01-01

Active control of structures has been under intensive development for the last ten years. Reference 2 reviews much of the identification and control technology for structural control developed during this time. The technology was initially focused on space structure and weapon applications; however, recently the technology is also being directed toward applications in manufacturing and transportation. Much of this technology focused on multiple-input/multiple-output (MIMO) identification and control methodology because many of the applications require a coordinated control involving multiple disturbances and control objectives where multiple actuators and sensors are necessary for high performance. There have been many optimal robust controlmore » methods developed for the design of MIMO robust control laws; however, there appears to be a significant gap between the theoretical development and experimental evaluation of control and identification methods to address structural control applications. Many methods have been developed for MIMO identification and control of structures, such as the Eigensystem Realization Algorithm (ERA), Q-Markov Covariance Equivalent Realization (Q-Markov COVER) for identification; and, Linear Quadratic Gaussian (LQG), Frequency Weighted LQG and H-/ii-synthesis methods for control. Upon implementation, many of the identification and control methods have shown limitations such as the excitation of unmodelled dynamics and sensitivity to system parameter variations. As a result, research on methods which address these problems have been conducted.« less

An historical survey of computational methods in optimal control.

NASA Technical Reports Server (NTRS)

Polak, E.

1973-01-01

Review of some of the salient theoretical developments in the specific area of optimal control algorithms. The first algorithms for optimal control were aimed at unconstrained problems and were derived by using first- and second-variation methods of the calculus of variations. These methods have subsequently been recognized as gradient, Newton-Raphson, or Gauss-Newton methods in function space. A much more recent addition to the arsenal of unconstrained optimal control algorithms are several variations of conjugate-gradient methods. At first, constrained optimal control problems could only be solved by exterior penalty function methods. Later algorithms specifically designed for constrained problems have appeared. Among these are methods for solving the unconstrained linear quadratic regulator problem, as well as certain constrained minimum-time and minimum-energy problems. Differential-dynamic programming was developed from dynamic programming considerations. The conditional-gradient method, the gradient-projection method, and a couple of feasible directions methods were obtained as extensions or adaptations of related algorithms for finite-dimensional problems. Finally, the so-called epsilon-methods combine the Ritz method with penalty function techniques.

Application of capability indices and control charts in the analytical method control strategy.

PubMed

Oliva, Alexis; Llabres Martinez, Matías

2017-08-01

In this study, we assessed the usefulness of control charts in combination with the process capability indices, C pm and C pk , in the control strategy of an analytical method. The traditional X-chart and moving range chart were used to monitor the analytical method over a 2-year period. The results confirmed that the analytical method is in-control and stable. Different criteria were used to establish the specifications limits (i.e. analyst requirements) for fixed method performance (i.e. method requirements). If the specification limits and control limits are equal in breadth, the method can be considered "capable" (C pm  = 1), but it does not satisfy the minimum method capability requirements proposed by Pearn and Shu (2003). Similar results were obtained using the C pk index. The method capability was also assessed as a function of method performance for fixed analyst requirements. The results indicate that the method does not meet the requirements of the analytical target approach. A real-example data of a SEC with light-scattering detection method was used as a model whereas previously published data were used to illustrate the applicability of the proposed approach. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fracture control methods for space vehicles. Volume 1: Fracture control design methods. [for space shuttle configuration planning

NASA Technical Reports Server (NTRS)

Liu, A. F.

1974-01-01

A systematic approach for applying methods for fracture control in the structural components of space vehicles consists of four major steps. The first step is to define the primary load-carrying structural elements and the type of load, environment, and design stress levels acting upon them. The second step is to identify the potential fracture-critical parts by means of a selection logic flow diagram. The third step is to evaluate the safe-life and fail-safe capabilities of the specified part. The last step in the sequence is to apply the control procedures that will prevent damage to the fracture-critical parts. The fracture control methods discussed include fatigue design and analysis methods, methods for preventing crack-like defects, fracture mechanics analysis methods, and nondestructive evaluation methods. An example problem is presented for evaluation of the safe-crack-growth capability of the space shuttle crew compartment skin structure.

A modified Finite Element-Transfer Matrix for control design of space structures

NASA Technical Reports Server (NTRS)

Tan, T.-M.; Yousuff, A.; Bahar, L. Y.; Konstandinidis, M.

1990-01-01

The Finite Element-Transfer Matrix (FETM) method was developed for reducing the computational efforts involved in structural analysis. While being widely used by structural analysts, this method does, however, have certain limitations, particularly when used for the control design of large flexible structures. In this paper, a new formulation based on the FETM method is presented. The new method effectively overcomes the limitations in the original FETM method, and also allows an easy construction of reduced models that are tailored for the control design. Other advantages of this new method include the ability to extract open loop frequencies and mode shapes with less computation, and simplification of the design procedures for output feedback, constrained compensation, and decentralized control. The development of this new method and the procedures for generating reduced models using this method are described in detail and the role of the reduced models in control design is discussed through an illustrative example.

Review of manual control methods for handheld maneuverable instruments.

PubMed

Fan, Chunman; Dodou, Dimitra; Breedveld, Paul

2013-06-01

By the introduction of new technologies, surgical procedures have been varying from free access in open surgery towards limited access in minimal access surgery. Improving access to difficult-to-reach anatomic sites, e.g. in neurosurgery or percutaneous interventions, needs advanced maneuverable instrumentation. Advances in maneuverable technology require the development of dedicated methods enabling surgeons to stay in direct, manual control of these complex instruments. This article gives an overview of the state-of-the-art in the development of manual control methods for handheld maneuverable instruments. It categorizes the manual control methods in three levels: a) number of steerable segments, b) number of Degrees Of Freedom (DOF), and c) coupling between control motion of the handle and steering motion of the tip. The literature research was completed by using Web of Science, Scopus and PubMed. The study shows that in controlling single steerable segments, direct as well as indirect control methods have been developed, whereas in controlling multiple steerable segments, a gradual shift can be noticed from parallel and serial control to integrated control. The development of multi-segmented maneuverable instruments is still at an early stage, and an intuitive and effective method to control them has to become a primary focus in the domain of minimal access surgery.

Tip-tilt disturbance model identification based on non-linear least squares fitting for Linear Quadratic Gaussian control

NASA Astrophysics Data System (ADS)

Yang, Kangjian; Yang, Ping; Wang, Shuai; Dong, Lizhi; Xu, Bing

2018-05-01

We propose a method to identify tip-tilt disturbance model for Linear Quadratic Gaussian control. This identification method based on Levenberg-Marquardt method conducts with a little prior information and no auxiliary system and it is convenient to identify the tip-tilt disturbance model on-line for real-time control. This identification method makes it easy that Linear Quadratic Gaussian control runs efficiently in different adaptive optics systems for vibration mitigation. The validity of the Linear Quadratic Gaussian control associated with this tip-tilt disturbance model identification method is verified by experimental data, which is conducted in replay mode by simulation.

Asymptotically suboptimal control of weakly interconnected dynamical systems

NASA Astrophysics Data System (ADS)

Dmitruk, N. M.; Kalinin, A. I.

2016-10-01

Optimal control problems for a group of systems with weak dynamical interconnections between its constituent subsystems are considered. A method for decentralized control is proposed which distributes the control actions between several controllers calculating in real time control inputs only for theirs subsystems based on the solution of the local optimal control problem. The local problem is solved by asymptotic methods that employ the representation of the weak interconnection by a small parameter. Combination of decentralized control and asymptotic methods allows to significantly reduce the dimension of the problems that have to be solved in the course of the control process.

An Optimal Control Modification to Model-Reference Adaptive Control for Fast Adaptation

NASA Technical Reports Server (NTRS)

Nguyen, Nhan T.; Krishnakumar, Kalmanje; Boskovic, Jovan

2008-01-01

This paper presents a method that can achieve fast adaptation for a class of model-reference adaptive control. It is well-known that standard model-reference adaptive control exhibits high-gain control behaviors when a large adaptive gain is used to achieve fast adaptation in order to reduce tracking error rapidly. High gain control creates high-frequency oscillations that can excite unmodeled dynamics and can lead to instability. The fast adaptation approach is based on the minimization of the squares of the tracking error, which is formulated as an optimal control problem. The necessary condition of optimality is used to derive an adaptive law using the gradient method. This adaptive law is shown to result in uniform boundedness of the tracking error by means of the Lyapunov s direct method. Furthermore, this adaptive law allows a large adaptive gain to be used without causing undesired high-gain control effects. The method is shown to be more robust than standard model-reference adaptive control. Simulations demonstrate the effectiveness of the proposed method.

Birth control pills - progestin only

MedlinePlus

... pregnant right away. When to Use a Backup Method Use a backup method of birth control, such as a condom, diaphragm, ... body may not absorb it. Use a backup method of birth control, and call your provider. You ...

Birth control pills - combination

MedlinePlus

... or mood swings. When to Use a Backup Method Use a backup method of birth control, such as condom, diaphragm, or ... body may not absorb it. Use a backup method of birth control for the rest of that ...

A Fuzzy-Based Control Method for Smoothing Power Fluctuations in Substations along High-Speed Railways

NASA Astrophysics Data System (ADS)

Sugio, Tetsuya; Yamamoto, Masayoshi; Funabiki, Shigeyuki

The use of an SMES (Superconducting Magnetic Energy Storage) for smoothing power fluctuations in a railway substation has been discussed. This paper proposes a smoothing control method based on fuzzy reasoning for reducing the SMES capacity at substations along high-speed railways. The proposed smoothing control method comprises three countermeasures for reduction of the SMES capacity. The first countermeasure involves modification of rule 1 for smoothing out the fluctuating electric power to its average value. The other countermeasures involve the modification of the central value of the stored energy control in the SMES and revision of the membership function in rule 2 for reduction of the SMES capacity. The SMES capacity in the proposed smoothing control method is reduced by 49.5% when compared to that in the nonrevised control method. It is confirmed by computer simulations that the proposed control method is suitable for smoothing out power fluctuations in substations along high-speed railways and for reducing the SMES capacity.

H∞ control of combustion in diesel engines using a discrete dynamics model

NASA Astrophysics Data System (ADS)

Hirata, Mitsuo; Ishizuki, Sota; Suzuki, Masayasu

2016-09-01

This paper proposes a control method for combustion in diesel engines using a discrete dynamics model. The proposed two-degree-of-freedom control scheme achieves not only good feedback properties such as disturbance suppression and robust stability but also a good transient response. The method includes a feedforward controller constructed from the inverse model of the plant, and a feedback controller designed by an Hcontrol method, which reduces the effect of the turbocharger lag. The effectiveness of the proposed method is evaluated via numerical simulations.

19 CFR 151.42 - Controls on unlading and gauging.

Code of Federal Regulations, 2010 CFR

2010-04-01

... Products § 151.42 Controls on unlading and gauging. (a) Methods of control. (1) Each port director shall... in bulk by vessel, truck, railroad car, pipeline, or other carrier. One of the following methods of... tank gauging is not available as a method of control. Vessel ullages will not be used to determine the...

19 CFR 151.42 - Controls on unlading and gauging.

Code of Federal Regulations, 2013 CFR

2013-04-01

... Products § 151.42 Controls on unlading and gauging. (a) Methods of control. (1) Each port director shall... in bulk by vessel, truck, railroad car, pipeline, or other carrier. One of the following methods of... tank gauging is not available as a method of control. Vessel ullages will not be used to determine the...

19 CFR 151.42 - Controls on unlading and gauging.

Code of Federal Regulations, 2012 CFR

2012-04-01

... Products § 151.42 Controls on unlading and gauging. (a) Methods of control. (1) Each port director shall... in bulk by vessel, truck, railroad car, pipeline, or other carrier. One of the following methods of... tank gauging is not available as a method of control. Vessel ullages will not be used to determine the...

19 CFR 151.42 - Controls on unlading and gauging.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Products § 151.42 Controls on unlading and gauging. (a) Methods of control. (1) Each port director shall... in bulk by vessel, truck, railroad car, pipeline, or other carrier. One of the following methods of... tank gauging is not available as a method of control. Vessel ullages will not be used to determine the...

The composition of heterogeneous control laws

NASA Technical Reports Server (NTRS)

Kuipers, Benjamin; Astrom, Karl

1991-01-01

The fuzzy control literature and industrial practice provide certain nonlinear methods for combining heterogeneous control laws, but these methods have been very difficult to analyze theoretically. An alternate formulation and extension of this approach is presented that has several practical and theoretical benefits. An example of heterogeneous control is given and two alternate analysis methods are presented.

Optimization of controllability and robustness of complex networks by edge directionality

NASA Astrophysics Data System (ADS)

Liang, Man; Jin, Suoqin; Wang, Dingjie; Zou, Xiufen

2016-09-01

Recently, controllability of complex networks has attracted enormous attention in various fields of science and engineering. How to optimize structural controllability has also become a significant issue. Previous studies have shown that an appropriate directional assignment can improve structural controllability; however, the evolution of the structural controllability of complex networks under attacks and cascading has always been ignored. To address this problem, this study proposes a new edge orientation method (NEOM) based on residual degree that changes the link direction while conserving topology and directionality. By comparing the results with those of previous methods in two random graph models and several realistic networks, our proposed approach is demonstrated to be an effective and competitive method for improving the structural controllability of complex networks. Moreover, numerical simulations show that our method is near-optimal in optimizing structural controllability. Strikingly, compared to the original network, our method maintains the structural controllability of the network under attacks and cascading, indicating that the NEOM can also enhance the robustness of controllability of networks. These results alter the view of the nature of controllability in complex networks, change the understanding of structural controllability and affect the design of network models to control such networks.

Force analysis of magnetic bearings with power-saving controls

NASA Technical Reports Server (NTRS)

Johnson, Dexter; Brown, Gerald V.; Inman, Daniel J.

1992-01-01

Most magnetic bearing control schemes use a bias current with a superimposed control current to linearize the relationship between the control current and the force it delivers. For most operating conditions, the existence of the bias current requires more power than alternative methods that do not use conventional bias. Two such methods are examined which diminish or eliminate bias current. In the typical bias control scheme it is found that for a harmonic control force command into a voltage limited transconductance amplifier, the desired force output is obtained only up to certain combinations of force amplitude and frequency. Above these values, the force amplitude is reduced and a phase lag occurs. The power saving alternative control schemes typically exhibit such deficiencies at even lower command frequencies and amplitudes. To assess the severity of these effects, a time history analysis of the force output is performed for the bias method and the alternative methods. Results of the analysis show that the alternative approaches may be viable. The various control methods examined were mathematically modeled using nondimensionalized variables to facilitate comparison of the various methods.

Keyboard before Head Tracking Depresses User Success in Remote Camera Control

NASA Astrophysics Data System (ADS)

Zhu, Dingyun; Gedeon, Tom; Taylor, Ken

In remote mining, operators of complex machinery have more tasks or devices to control than they have hands. For example, operating a rock breaker requires two handed joystick control to position and fire the jackhammer, leaving the camera control to either automatic control or require the operator to switch between controls. We modelled such a teleoperated setting by performing experiments using a simple physical game analogue, being a half size table soccer game with two handles. The complex camera angles of the mining application were modelled by obscuring the direct view of the play area and the use of a Pan-Tilt-Zoom (PTZ) camera. The camera control was via either a keyboard or via head tracking using two different sets of head gestures called “head motion” and “head flicking” for turning camera motion on/off. Our results show that the head motion control was able to provide a comparable performance to using a keyboard, while head flicking was significantly worse. In addition, the sequence of use of the three control methods is highly significant. It appears that use of the keyboard first depresses successful use of the head tracking methods, with significantly better results when one of the head tracking methods was used first. Analysis of the qualitative survey data collected supports that the worst (by performance) method was disliked by participants. Surprisingly, use of that worst method as the first control method significantly enhanced performance using the other two control methods.

Fast spacecraft adaptive attitude tracking control through immersion and invariance design

NASA Astrophysics Data System (ADS)

Wen, Haowei; Yue, Xiaokui; Li, Peng; Yuan, Jianping

2017-10-01

This paper presents a novel non-certainty-equivalence adaptive control method for the attitude tracking control problem of spacecraft with inertia uncertainties. The proposed immersion and invariance (I&I) based adaptation law provides a more direct and flexible approach to circumvent the limitations of the basic I&I method without employing any filter signal. By virtue of the adaptation high-gain equivalence property derived from the proposed adaptive method, the closed-loop adaptive system with a low adaptation gain could recover the high adaptation gain performance of the filter-based I&I method, and the resulting control torque demands during the initial transient has been significantly reduced. A special feature of this method is that the convergence of the parameter estimation error has been observably improved by utilizing an adaptation gain matrix instead of a single adaptation gain value. Numerical simulations are presented to highlight the various benefits of the proposed method compared with the certainty-equivalence-based control method and filter-based I&I control schemes.

Study on model current predictive control method of PV grid- connected inverters systems with voltage sag

NASA Astrophysics Data System (ADS)

Jin, N.; Yang, F.; Shang, S. Y.; Tao, T.; Liu, J. S.

2016-08-01

According to the limitations of the LVRT technology of traditional photovoltaic inverter existed, this paper proposes a low voltage ride through (LVRT) control method based on model current predictive control (MCPC). This method can effectively improve the photovoltaic inverter output characteristics and response speed. The MCPC method of photovoltaic grid-connected inverter designed, the sum of the absolute value of the predictive current and the given current error is adopted as the cost function with the model predictive control method. According to the MCPC, the optimal space voltage vector is selected. Photovoltaic inverter has achieved automatically switches of priority active or reactive power control of two control modes according to the different operating states, which effectively improve the inverter capability of LVRT. The simulation and experimental results proves that the proposed method is correct and effective.

Robust control of nonlinear MAGLEV suspension system with mismatched uncertainties via DOBC approach.

PubMed

Yang, Jun; Zolotas, Argyrios; Chen, Wen-Hua; Michail, Konstantinos; Li, Shihua

2011-07-01

Robust control of a class of uncertain systems that have disturbances and uncertainties not satisfying "matching" condition is investigated in this paper via a disturbance observer based control (DOBC) approach. In the context of this paper, "matched" disturbances/uncertainties stand for the disturbances/uncertainties entering the system through the same channels as control inputs. By properly designing a disturbance compensation gain, a novel composite controller is proposed to counteract the "mismatched" lumped disturbances from the output channels. The proposed method significantly extends the applicability of the DOBC methods. Rigorous stability analysis of the closed-loop system with the proposed method is established under mild assumptions. The proposed method is applied to a nonlinear MAGnetic LEViation (MAGLEV) suspension system. Simulation shows that compared to the widely used integral control method, the proposed method provides significantly improved disturbance rejection and robustness against load variation. Copyright © 2011 ISA. Published by Elsevier Ltd. All rights reserved.

Battery charging control methods, electric vehicle charging methods, battery charging apparatuses and rechargeable battery systems

DOEpatents

Tuffner, Francis K [Richland, WA; Kintner-Meyer, Michael C. W. [Richland, WA; Hammerstrom, Donald J [West Richland, WA; Pratt, Richard M [Richland, WA

2012-05-22

Battery charging control methods, electric vehicle charging methods, battery charging apparatuses and rechargeable battery systems. According to one aspect, a battery charging control method includes accessing information regarding a presence of at least one of a surplus and a deficiency of electrical energy upon an electrical power distribution system at a plurality of different moments in time, and using the information, controlling an adjustment of an amount of the electrical energy provided from the electrical power distribution system to a rechargeable battery to charge the rechargeable battery.

A Hierarchical Model Predictive Tracking Control for Independent Four-Wheel Driving/Steering Vehicles with Coaxial Steering Mechanism

NASA Astrophysics Data System (ADS)

Itoh, Masato; Hagimori, Yuki; Nonaka, Kenichiro; Sekiguchi, Kazuma

2016-09-01

In this study, we apply a hierarchical model predictive control to omni-directional mobile vehicle, and improve the tracking performance. We deal with an independent four-wheel driving/steering vehicle (IFWDS) equipped with four coaxial steering mechanisms (CSM). The coaxial steering mechanism is a special one composed of two steering joints on the same axis. In our previous study with respect to IFWDS with ideal steering, we proposed a model predictive tracking control. However, this method did not consider constraints of the coaxial steering mechanism which causes delay of steering. We also proposed a model predictive steering control considering constraints of this mechanism. In this study, we propose a hierarchical system combining above two control methods for IFWDS. An upper controller, which deals with vehicle kinematics, runs a model predictive tracking control, and a lower controller, which considers constraints of coaxial steering mechanism, runs a model predictive steering control which tracks the predicted steering angle optimized an upper controller. We verify the superiority of this method by comparing this method with the previous method.

Closed-loop and robust control of quantum systems.

PubMed

Chen, Chunlin; Wang, Lin-Cheng; Wang, Yuanlong

2013-01-01

For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control) have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA), and reinforcement learning (RL) methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control as H(∞) control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention.

Chemical control methods and tools

Treesearch

Steven Manning; James Miller

2011-01-01

After determining the best course of action for control of an invasive plant population, it is important to understand the variety of methods available to the integrated pest management professional. A variety of methods are now widely used in managing invasive plants in natural areas, including chemical, mechanical, and cultural control methods. Once the preferred...

Active vibration control for flexible rotor by optimal direct-output feedback control

NASA Technical Reports Server (NTRS)

Nonami, Kenzou; Dirusso, Eliseo; Fleming, David P.

1989-01-01

Experimental research tests were performed to actively control the rotor vibrations of a flexible rotor mounted on flexible bearing supports. The active control method used in the tests is called optimal direct-output feedback control. This method uses four electrodynamic actuators to apply control forces directly to the bearing housings in order to achieve effective vibration control of the rotor. The force actuators are controlled by an analog controller that accepts rotor displacement as input. The controller is programmed with experimentally determined feedback coefficients; the output is a control signal to the force actuators. The tests showed that this active control method reduced the rotor resonance peaks due to unbalance from approximately 250 micrometers down to approximately 25 micrometers (essentially runout level). The tests were conducted over a speed range from 0 to 10,000 rpm; the rotor system had nine critical speeds within this speed range. The method was effective in significantly reducing the rotor vibration for all of the vibration modes and critical speeds.

Active vibration control for flexible rotor by optimal direct-output feedback control

NASA Technical Reports Server (NTRS)

Nonami, K.; Dirusso, E.; Fleming, D. P.

1989-01-01

Experimental research tests were performed to actively control the rotor vibrations of a flexible rotor mounted on flexible bearing supports. The active control method used in the tests is called optimal direct-output feedback control. This method uses four electrodynamic actuators to apply control forces directly to the bearing housings in order to achieve effective vibration control of the rotor. The force actuators are controlled by an analog controller that accepts rotor displacement as input. The controller is programmed with experimentally determined feedback coefficients; the output is a control signal to the force actuators. The tests showed that this active control method reduced the rotor resonance peaks due to unbalance from approximately 250 microns down to approximately 25 microns (essentially runout level). The tests were conducted over a speed range from 0 to 10,000 rpm; the rotor system had nine critical speeds within this speed range. The method was effective in significantly reducing the rotor vibration for all of the vibration modes and critical speeds.

Evaluation of pH monitoring as a method of processor control.

PubMed

Stears, J G; Gray, J E; Winkler, N T

1979-01-01

Sensitometry and pH values of the developer solution were compared in controlled over-replenishment, developer depletion, fixer contamination experiments, and on a daily quality control basis. The purpose of these comparisons was to evaluate the potential of pH monitoring as a method of processor control, or a supplement to sensitometry as a method of quality control. Reasonable correlation was found between pH values and film density in two of the three experiments but little or no correlation was found in the third experiment and on a day-to-day basis. The conclusion drawn from these comparisons is that pH monitoring has several limitations which render it unsuitable as a method of daily processor quality control as either a primary or supplementary technique. Sensitometry takes into account all the variables encountered in film processing and is the clear method of choice for processor quality control.

Study on a magnetic spiral-type wireless capsule endoscope controlled by rotational external permanent magnet

NASA Astrophysics Data System (ADS)

Ye, Bo; Zhang, Wei; Sun, Zhen-jun; Guo, Lin; Deng, Chao; Chen, Ya-qi; Zhang, Hong-hai; Liu, Sheng

2015-12-01

In this paper, the authors propose rotating an external permanent magnet (EPM) to manipulate the synchronous rotation of a magnetic spiral-type wireless capsule endoscope (WCE), and the synchronous rotation of the WCE is converted to its translational motion in intestinal tract. In order to preliminarily verify the feasibility of this method, a handheld actuator (HA) controlled by micro controller unit, a magnetic spiral-type WCE and a bracket were fabricated, theoretical analysis and simulations about the control distance of this method were performed, and in ex-vivo tests were examined in porcine small intestine to verify the control distance and control performances of this method. It was demonstrated that this method showed good performances in controlling the translational motion of the magnetic spiral-type WCE, and this method has great potential to be used in clinical application.

Barrier Methods of Birth Control: Spermicide, Condom, Sponge, Diaphragm, and Cervical Cap

MedlinePlus

... Education & Events Advocacy For Patients About ACOG Barrier Methods of Birth Control: Spermicide, Condom, Sponge, Diaphragm, and ... Cervical Cap FAQ022, March 2018 PDF Format Barrier Methods of Birth Control: Spermicide, Condom, Sponge, Diaphragm, and ...

Development of a control algorithm for the ultrasound scanning robot (NCCUSR) using ultrasound image and force feedback.

PubMed

Kim, Yeoun Jae; Seo, Jong Hyun; Kim, Hong Rae; Kim, Kwang Gi

2017-06-01

Clinicians who frequently perform ultrasound scanning procedures often suffer from musculoskeletal disorders, arthritis, and myalgias. To minimize their occurrence and to assist clinicians, ultrasound scanning robots have been developed worldwide. Although, to date, there is still no commercially available ultrasound scanning robot, many control methods have been suggested and researched. These control algorithms are either image based or force based. If the ultrasound scanning robot control algorithm was a combination of the two algorithms, it could benefit from the advantage of each one. However, there are no existing control methods for ultrasound scanning robots that combine force control and image analysis. Therefore, in this work, a control algorithm is developed for an ultrasound scanning robot using force feedback and ultrasound image analysis. A manipulator-type ultrasound scanning robot named 'NCCUSR' is developed and a control algorithm for this robot is suggested and verified. First, conventional hybrid position-force control is implemented for the robot and the hybrid position-force control algorithm is combined with ultrasound image analysis to fully control the robot. The control method is verified using a thyroid phantom. It was found that the proposed algorithm can be applied to control the ultrasound scanning robot and experimental outcomes suggest that the images acquired using the proposed control method can yield a rating score that is equivalent to images acquired directly by the clinicians. The proposed control method can be applied to control the ultrasound scanning robot. However, more work must be completed to verify the proposed control method in order to become clinically feasible. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The design of multirate digital control systems

NASA Technical Reports Server (NTRS)

Berg, M. C.

1986-01-01

The successive loop closures synthesis method is the only method for multirate (MR) synthesis in common use. A new method for MR synthesis is introduced which requires a gradient-search solution to a constrained optimization problem. Some advantages of this method are that the control laws for all control loops are synthesized simultaneously, taking full advantage of all cross-coupling effects, and that simple, low-order compensator structures are easily accomodated. The algorithm and associated computer program for solving the constrained optimization problem are described. The successive loop closures , optimal control, and constrained optimization synthesis methods are applied to two example design problems. A series of compensator pairs are synthesized for each example problem. The succesive loop closure, optimal control, and constrained optimization synthesis methods are compared, in the context of the two design problems.

Controller design via structural reduced modeling by FETM

NASA Technical Reports Server (NTRS)

Yousuff, A.

1986-01-01

The Finite Element - Transfer Matrix (FETM) method has been developed to reduce the computations involved in analysis of structures. This widely accepted method, however, has certain limitations, and does not directly produce reduced models for control design. To overcome these shortcomings, a modification of FETM method has been developed. The modified FETM method easily produces reduced models that are tailored toward subsequent control design. Other features of this method are its ability to: (1) extract open loop frequencies and mode shapes with less computations, (2) overcome limitations of the original FETM method, and (3) simplify the procedures for output feedback, constrained compensation, and decentralized control. This semi annual report presents the development of the modified FETM, and through an example, illustrates its applicability to an output feedback and a decentralized control design.

Method for determining how to operate and control wind turbine arrays in utility systems

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

Javid, S.H.; Hauth, R.L.; Younkins, T.D.

1984-01-01

A method for determining how utility wind turbine arrays should be controlled and operated on the load frequency control time-scale is presented. Initial considerations for setting wind turbine control requirements are followed by a description of open loop operation and of closed loop and feed forward wind turbine array control concepts. The impact of variations in array output on meeting minimum criteria are developed. The method for determining the required control functions is then presented and results are tabulated. (LEW)

Power system

DOEpatents

Hickam, Christopher Dale [Glasford, IL

2008-03-18

A power system includes a prime mover, a transmission, and a fluid coupler having a selectively engageable lockup clutch. The fluid coupler may be drivingly connected between the prime mover and the transmission. Additionally, the power system may include a motor/generator drivingly connected to at least one of the prime mover and the transmission. The power-system may also include power-system controls configured to execute a control method. The control method may include selecting one of a plurality of modes of operation of the power system. Additionally, the control method may include controlling the operating state of the lockup clutch dependent upon the mode of operation selected. The control method may also include controlling the operating state of the motor/generator dependent upon the mode of operation selected.

30 CFR 28.33 - Quality control test methods, equipment, and records; review by MSHA; revocation of approval.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Quality control test methods, equipment, and... USE WITH DIRECT CURRENT IN PROVIDING SHORT-CIRCUIT PROTECTION FOR TRAILING CABLES IN COAL MINES Quality Control § 28.33 Quality control test methods, equipment, and records; review by MSHA; revocation...

30 CFR 28.33 - Quality control test methods, equipment, and records; review by MSHA; revocation of approval.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Quality control test methods, equipment, and... USE WITH DIRECT CURRENT IN PROVIDING SHORT-CIRCUIT PROTECTION FOR TRAILING CABLES IN COAL MINES Quality Control § 28.33 Quality control test methods, equipment, and records; review by MSHA; revocation...

30 CFR 28.33 - Quality control test methods, equipment, and records; review by MSHA; revocation of approval.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Quality control test methods, equipment, and... USE WITH DIRECT CURRENT IN PROVIDING SHORT-CIRCUIT PROTECTION FOR TRAILING CABLES IN COAL MINES Quality Control § 28.33 Quality control test methods, equipment, and records; review by MSHA; revocation...

30 CFR 28.33 - Quality control test methods, equipment, and records; review by MSHA; revocation of approval.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Quality control test methods, equipment, and... USE WITH DIRECT CURRENT IN PROVIDING SHORT-CIRCUIT PROTECTION FOR TRAILING CABLES IN COAL MINES Quality Control § 28.33 Quality control test methods, equipment, and records; review by MSHA; revocation...

30 CFR 28.33 - Quality control test methods, equipment, and records; review by MSHA; revocation of approval.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Quality control test methods, equipment, and... USE WITH DIRECT CURRENT IN PROVIDING SHORT-CIRCUIT PROTECTION FOR TRAILING CABLES IN COAL MINES Quality Control § 28.33 Quality control test methods, equipment, and records; review by MSHA; revocation...

Stereo Sound Field Controller Design Using Partial Model Matching on the Frequency Domain

NASA Astrophysics Data System (ADS)

Kumon, Makoto; Miike, Katsuhiro; Eguchi, Kazuki; Mizumoto, Ikuro; Iwai, Zenta

The objective of sound field control is to make the acoustic characteristics of a listening room close to those of the desired system. Conventional methods apply feedforward controllers, such as digital filters, to achieve this objective. However, feedback controllers are also necessary in order to attenuate noise or to compensate the uncertainty of the acoustic characteristics of the listening room. Since acoustic characteristics are well modeled on the frequency domain, it is efficient to design controllers with respect to frequency responses, but it is difficult to design a multi input multi output (MIMO) control system on a wide frequency domain. In the present study, a partial model matching method on the frequency domain was adopted because this method requires only sampled data, rather than complex mathematical models of the plant, in order to design controllers for MIMO systems. The partial model matching method was applied to design two-degree-of-freedom controllers for acoustic equalization and noise reduction. Experiments demonstrated effectiveness of the proposed method.

A new integrated evaluation method of heavy metals pollution control during melting and sintering of MSWI fly ash.

PubMed

Li, Rundong; Li, Yanlong; Yang, Tianhua; Wang, Lei; Wang, Weiyun

2015-05-30

Evaluations of technologies for heavy metal control mainly examine the residual and leaching rates of a single heavy metal, such that developed evaluation method have no coordination or uniqueness and are therefore unsuitable for hazard control effect evaluation. An overall pollution toxicity index (OPTI) was established in this paper, based on the developed index, an integrated evaluation method of heavy metal pollution control was established. Application of this method in the melting and sintering of fly ash revealed the following results: The integrated control efficiency of the melting process was higher in all instances than that of the sintering process. The lowest integrated control efficiency of melting was 56.2%, and the highest integrated control efficiency of sintering was 46.6%. Using the same technology, higher integrated control efficiency conditions were all achieved with lower temperatures and shorter times. This study demonstrated the unification and consistency of this method. Copyright © 2015 Elsevier B.V. All rights reserved.

Plant management in natural areas: balancing chemical, mechanical, and cultural control methods

Treesearch

Steven Manning; James Miller

2011-01-01

After determining the best course of action for control of an invasive plant population, it is important to understand the variety of methods available to the integrated pest management professional. A variety of methods are now widely used in managing invasive plants in natural areas, including chemical, mechanical, and cultural control methods. Once the preferred...

COMSAC: Computational Methods for Stability and Control. Part 1

NASA Technical Reports Server (NTRS)

Fremaux, C. Michael (Compiler); Hall, Robert M. (Compiler)

2004-01-01

Work on stability and control included the following reports:Introductory Remarks; Introduction to Computational Methods for Stability and Control (COMSAC); Stability & Control Challenges for COMSAC: a NASA Langley Perspective; Emerging CFD Capabilities and Outlook A NASA Langley Perspective; The Role for Computational Fluid Dynamics for Stability and Control:Is it Time?; Northrop Grumman Perspective on COMSAC; Boeing Integrated Defense Systems Perspective on COMSAC; Computational Methods in Stability and Control:WPAFB Perspective; Perspective: Raytheon Aircraft Company; A Greybeard's View of the State of Aerodynamic Prediction; Computational Methods for Stability and Control: A Perspective; Boeing TacAir Stability and Control Issues for Computational Fluid Dynamics; NAVAIR S&C Issues for CFD; An S&C Perspective on CFD; Issues, Challenges & Payoffs: A Boeing User s Perspective on CFD for S&C; and Stability and Control in Computational Simulations for Conceptual and Preliminary Design: the Past, Today, and Future?

Experimental research of flow servo-valve

NASA Astrophysics Data System (ADS)

Takosoglu, Jakub

Positional control of pneumatic drives is particularly important in pneumatic systems. Some methods of positioning pneumatic cylinders for changeover and tracking control are known. Choking method is the most development-oriented and has the greatest potential. An optimal and effective method, particularly when applied to pneumatic drives, has been searched for a long time. Sophisticated control systems with algorithms utilizing artificial intelligence methods are designed therefor. In order to design the control algorithm, knowledge about real parameters of servo-valves used in control systems of electro-pneumatic servo-drives is required. The paper presents the experimental research of flow servo-valve.

Can Land Managers Control Japanese Knotweed? Lessons from Control Tests in Belgium

NASA Astrophysics Data System (ADS)

Delbart, Emmanuel; Mahy, Grégory; Weickmans, Bernard; Henriet, François; Crémer, Sébastien; Pieret, Nora; Vanderhoeven, Sonia; Monty, Arnaud

2012-12-01

Japanese knotweed Fallopia japonica is an extremely abundant invasive plant in Belgium and surrounding countries. To date, no eradication method is available for land managers facing the invasion of this rhizomatous plant. We tested different chemical herbicides with two application methods (spraying and stem injection), as well as mechanical treatments, on knotweed clones throughout southern Belgium. The tested control methods were selected to be potentially usable by managers, e.g., using legally accepted rates for herbicides. Stem volume, height and density reduction were assessed after one or two years, depending on the control method. Labor estimations were made for each control method. No tested control method completely eradicated the clones. Stem injection with glyphosate-based herbicide (3.6 kg ha-1 of acid equivalent glyphosate) caused the most damage, i.e., no sprouting shoots were observed the year following the injection. The following year, though, stunted shoots appeared. Among the mechanical control methods, repeated cuts combined with native tree transplanting most appreciably reduced knotweed development. The most efficient methods we tested could curb knotweed invasion, but are not likely to be effective in eradicating the species. As such, they should be included in a more integrated restoration strategy, together with prevention and public awareness campaigns.

A method for obtaining reduced-order control laws for high-order systems using optimization techniques

NASA Technical Reports Server (NTRS)

Mukhopadhyay, V.; Newsom, J. R.; Abel, I.

1981-01-01

A method of synthesizing reduced-order optimal feedback control laws for a high-order system is developed. A nonlinear programming algorithm is employed to search for the control law design variables that minimize a performance index defined by a weighted sum of mean-square steady-state responses and control inputs. An analogy with the linear quadractic Gaussian solution is utilized to select a set of design variables and their initial values. To improve the stability margins of the system, an input-noise adjustment procedure is used in the design algorithm. The method is applied to the synthesis of an active flutter-suppression control law for a wind tunnel model of an aeroelastic wing. The reduced-order controller is compared with the corresponding full-order controller and found to provide nearly optimal performance. The performance of the present method appeared to be superior to that of two other control law order-reduction methods. It is concluded that by using the present algorithm, nearly optimal low-order control laws with good stability margins can be synthesized.

Aircraft digital control design methods

NASA Technical Reports Server (NTRS)

Powell, J. D.; Parsons, E.; Tashker, M. G.

1976-01-01

Variations in design methods for aircraft digital flight control are evaluated and compared. The methods fall into two categories; those where the design is done in the continuous domain (or s plane) and those where the design is done in the discrete domain (or z plane). Design method fidelity is evaluated by examining closed loop root movement and the frequency response of the discretely controlled continuous aircraft. It was found that all methods provided acceptable performance for sample rates greater than 10 cps except the uncompensated s plane design method which was acceptable above 20 cps. A design procedure based on optimal control methods was proposed that provided the best fidelity at very slow sample rates and required no design iterations for changing sample rates.

Dynamics and Control of Flexible Space Vehicles

NASA Technical Reports Server (NTRS)

Likins, P. W.

1970-01-01

The purpose of this report is twofold: (1) to survey the established analytic procedures for the simulation of controlled flexible space vehicles, and (2) to develop in detail methods that employ a combination of discrete and distributed ("modal") coordinates, i.e., the hybrid-coordinate methods. Analytic procedures are described in three categories: (1) discrete-coordinate methods, (2) hybrid-coordinate methods, and (3) vehicle normal-coordinate methods. Each of these approaches is described and analyzed for its advantages and disadvantages, and each is found to have an area of applicability. The hybrid-coordinate method combines the efficiency of the vehicle normal-coordinate method with the versatility of the discrete-coordinate method, and appears to have the widest range of practical application. The results in this report have practical utility in two areas: (1) complex digital computer simulation of flexible space vehicles of arbitrary configuration subject to realistic control laws, and (2) preliminary control system design based on transfer functions for linearized models of dynamics and control laws.

Birth Control Explorer

MedlinePlus

... STIs Media Facebook Twitter Tumblr Shares · 0 Birth Control Explorer Sort by all methods most effective methods ... You are here Home » Birth Control Explorer Birth Control Explorer If you’re having sex —or if ...

Approximation methods for control of structural acoustics models with piezoceramic actuators

NASA Astrophysics Data System (ADS)

Banks, H. T.; Fang, W.; Silcox, R. J.; Smith, R. C.

1993-01-01

The active control of acoustic pressure in a 2-D cavity with a flexible boundary (a beam) is considered. Specifically, this control is implemented via piezoceramic patches on the beam which produces pure bending moments. The incorporation of the feedback control in this manner leads to a system with an unbounded input term. Approximation methods in this manner leads to a system with an unbounded input term. Approximation methods in this manner leads to a system with an unbounded input team. Approximation methods in the context of linear quadratic regulator (LQR) state space control formulation are discussed and numerical results demonstrating the effectiveness of this approach in computing feedback controls for noise reduction are presented.

Numerical optimization methods for controlled systems with parameters

NASA Astrophysics Data System (ADS)

Tyatyushkin, A. I.

2017-10-01

First- and second-order numerical methods for optimizing controlled dynamical systems with parameters are discussed. In unconstrained-parameter problems, the control parameters are optimized by applying the conjugate gradient method. A more accurate numerical solution in these problems is produced by Newton's method based on a second-order functional increment formula. Next, a general optimal control problem with state constraints and parameters involved on the righthand sides of the controlled system and in the initial conditions is considered. This complicated problem is reduced to a mathematical programming one, followed by the search for optimal parameter values and control functions by applying a multimethod algorithm. The performance of the proposed technique is demonstrated by solving application problems.

An EMG-Based Control for an Upper-Limb Power-Assist Exoskeleton Robot.

PubMed

Kiguchi, K; Hayashi, Y

2012-08-01

Many kinds of power-assist robots have been developed in order to assist self-rehabilitation and/or daily life motions of physically weak persons. Several kinds of control methods have been proposed to control the power-assist robots according to user's motion intention. In this paper, an electromyogram (EMG)-based impedance control method for an upper-limb power-assist exoskeleton robot is proposed to control the robot in accordance with the user's motion intention. The proposed method is simple, easy to design, humanlike, and adaptable to any user. A neurofuzzy matrix modifier is applied to make the controller adaptable to any users. Not only the characteristics of EMG signals but also the characteristics of human body are taken into account in the proposed method. The effectiveness of the proposed method was evaluated by the experiments.

Inventory Management for Irregular Shipment of Goods in Distribution Centre

NASA Astrophysics Data System (ADS)

Takeda, Hitoshi; Kitaoka, Masatoshi; Usuki, Jun

2016-01-01

The shipping amount of commodity goods (Foods, confectionery, dairy products, such as public cosmetic pharmaceutical products) changes irregularly at the distribution center dealing with the general consumer goods. Because the shipment time and the amount of the shipment are irregular, the demand forecast becomes very difficult. For this, the inventory control becomes difficult, too. It cannot be applied to the shipment of the commodity by the conventional inventory control methods. This paper proposes the method for inventory control by cumulative flow curve method. It proposed the method of deciding the order quantity of the inventory control by the cumulative flow curve. Here, it proposes three methods. 1) Power method,2) Polynomial method and 3)Revised Holt's linear method that forecasts data with trends that is a kind of exponential smoothing method. This paper compares the economics of the conventional method, which is managed by the experienced and three new proposed methods. And, the effectiveness of the proposal method is verified from the numerical calculations.

29 CFR 1910.1026 - Chromium (VI).

Code of Federal Regulations, 2012 CFR

2012-07-01

... resembling the processes, types of material, control methods, work practices, and environmental conditions in... resembling the processes, types of material, control methods, work practices, and environmental conditions in..., work practices, or control methods that may result in new or additional exposures to chromium (VI), or...

29 CFR 1910.1026 - Chromium (VI).

Code of Federal Regulations, 2014 CFR

2014-07-01

... resembling the processes, types of material, control methods, work practices, and environmental conditions in... resembling the processes, types of material, control methods, work practices, and environmental conditions in..., work practices, or control methods that may result in new or additional exposures to chromium (VI), or...

A Mathematical Model for Railway Control Systems

NASA Technical Reports Server (NTRS)

Hoover, D. N.

1996-01-01

We present a general method for modeling safety aspects of railway control systems. Using our modeling method, one can progressively refine an abstract railway safety model, sucessively adding layers of detail about how a real system actually operates, while maintaining a safety property that refines the original abstract safety property. This method supports a top-down approach to specification of railway control systems and to proof of a variety of safety-related properties. We demonstrate our method by proving safety of the classical block control system.

Method and apparatus for controlling LCL converters using asymmetric voltage cancellation techniques

DOEpatents

Wu, Hunter; Sealy, Kylee Devro; Sharp, Bryan Thomas; Gilchrist, Aaron

2016-01-26

A method and apparatus for LCL resonant converter control utilizing Asymmetric Voltage Cancellation is described. The methods to determine the optimal trajectory of the control variables are discussed. Practical implementations of sensing load parameters are included. Simple PI, PID and fuzzy logic controllers are included with AVC for achieving good transient response characteristics with output current regulation.

Experiments study on attitude coupling control method for flexible spacecraft

NASA Astrophysics Data System (ADS)

Wang, Jie; Li, Dongxu

2018-06-01

High pointing accuracy and stabilization are significant for spacecrafts to carry out Earth observing, laser communication and space exploration missions. However, when a spacecraft undergoes large angle maneuver, the excited elastic oscillation of flexible appendages, for instance, solar wing and onboard antenna, would downgrade the performance of the spacecraft platform. This paper proposes a coupling control method, which synthesizes the adaptive sliding mode controller and the positive position feedback (PPF) controller, to control the attitude and suppress the elastic vibration simultaneously. Because of its prominent performance for attitude tracking and stabilization, the proposed method is capable of slewing the flexible spacecraft with a large angle. Also, the method is robust to parametric uncertainties of the spacecraft model. Numerical simulations are carried out with a hub-plate system which undergoes a single-axis attitude maneuver. An attitude control testbed for the flexible spacecraft is established and experiments are conducted to validate the coupling control method. Both numerical and experimental results demonstrate that the method discussed above can effectively decrease the stabilization time and improve the attitude accuracy of the flexible spacecraft.

Coordinated control of active and reactive power of distribution network with distributed PV cluster via model predictive control

NASA Astrophysics Data System (ADS)

Ji, Yu; Sheng, Wanxing; Jin, Wei; Wu, Ming; Liu, Haitao; Chen, Feng

2018-02-01

A coordinated optimal control method of active and reactive power of distribution network with distributed PV cluster based on model predictive control is proposed in this paper. The method divides the control process into long-time scale optimal control and short-time scale optimal control with multi-step optimization. The models are transformed into a second-order cone programming problem due to the non-convex and nonlinear of the optimal models which are hard to be solved. An improved IEEE 33-bus distribution network system is used to analyse the feasibility and the effectiveness of the proposed control method

Closed-Loop and Robust Control of Quantum Systems

PubMed Central

Wang, Lin-Cheng

2013-01-01

For most practical quantum control systems, it is important and difficult to attain robustness and reliability due to unavoidable uncertainties in the system dynamics or models. Three kinds of typical approaches (e.g., closed-loop learning control, feedback control, and robust control) have been proved to be effective to solve these problems. This work presents a self-contained survey on the closed-loop and robust control of quantum systems, as well as a brief introduction to a selection of basic theories and methods in this research area, to provide interested readers with a general idea for further studies. In the area of closed-loop learning control of quantum systems, we survey and introduce such learning control methods as gradient-based methods, genetic algorithms (GA), and reinforcement learning (RL) methods from a unified point of view of exploring the quantum control landscapes. For the feedback control approach, the paper surveys three control strategies including Lyapunov control, measurement-based control, and coherent-feedback control. Then such topics in the field of quantum robust control as H ∞ control, sliding mode control, quantum risk-sensitive control, and quantum ensemble control are reviewed. The paper concludes with a perspective of future research directions that are likely to attract more attention. PMID:23997680

Methods of Si based ceramic components volatilization control in a gas turbine engine

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

Garcia-Crespo, Andres Jose; Delvaux, John; Dion Ouellet, Noemie

A method of controlling volatilization of silicon based components in a gas turbine engine includes measuring, estimating and/or predicting a variable related to operation of the gas turbine engine; correlating the variable to determine an amount of silicon to control volatilization of the silicon based components in the gas turbine engine; and injecting silicon into the gas turbine engine to control volatilization of the silicon based components. A gas turbine with a compressor, combustion system, turbine section and silicon injection system may be controlled by a controller that implements the control method.

Full-order observer for direct torque control of induction motor based on constant V/F control technique.

PubMed

Pimkumwong, Narongrit; Wang, Ming-Shyan

2018-02-01

This paper presents another control method for the three-phase induction motor that is direct torque control based on constant voltage per frequency control technique. This method uses the magnitude of stator flux and torque errors to generate the stator voltage and phase angle references for controlling the induction motor by using constant voltage per frequency control method. Instead of hysteresis comparators and optimum switching table, the PI controllers and space vector modulation technique are used to reduce torque and stator-flux ripples and achieve constant switching frequency. Moreover, the coordinate transformations are not required. To implement this control method, a full-order observer is used to estimate stator flux and overcome the problems from drift and saturation in using pure integrator. The feedback gains are designed by simple manner to improve the convergence of stator flux estimation, especially in low speed range. Furthermore, the necessary conditions to maintain the stability for feedback gain design are introduced. The simulation and experimental results show accurate and stable operation of the introduced estimator and good dynamic response of the proposed control method. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Decentralized PID controller for TITO systems using characteristic ratio assignment with an experimental application.

PubMed

Hajare, V D; Patre, B M

2015-11-01

This paper presents a decentralized PID controller design method for two input two output (TITO) systems with time delay using characteristic ratio assignment (CRA) method. The ability of CRA method to design controller for desired transient response has been explored for TITO systems. The design methodology uses an ideal decoupler to reduce the interaction. Each decoupled subsystem is reduced to first order plus dead time (FOPDT) model to design independent diagonal controllers. Based on specified overshoot and settling time, the controller parameters are computed using CRA method. To verify performance of the proposed controller, two benchmark simulation examples are presented. To demonstrate applicability of the proposed controller, experimentation is performed on real life interacting coupled tank level system. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

[Study on Accurately Controlling Discharge Energy Method Used in External Defibrillator].

PubMed

Song, Biao; Wang, Jianfei; Jin, Lian; Wu, Xiaomei

2016-01-01

This paper introduces a new method which controls discharge energy accurately. It is achieved by calculating target voltage based on transthoracic impedance and accurately controlling charging voltage and discharge pulse width. A new defibrillator is designed and programmed using this method. The test results show that this method is valid and applicable to all kinds of external defibrillators.

Simplified power control method for cellular mobile communication

NASA Astrophysics Data System (ADS)

Leung, Y. W.

1994-04-01

The centralized power control (CPC) method measures the gain of the communication links between every mobile and every base station in the cochannel cells and determines optimal transmitter power to maximize the minimum carrier-to-interference ratio. The authors propose a simplified power control method which has nearly the same performance as the CPC method but which involves much smaller measurement overhead.

Control Theory and Statistical Generalizations.

ERIC Educational Resources Information Center

Powers, William T.

1990-01-01

Contrasts modeling methods in control theory to the methods of statistical generalizations in empirical studies of human or animal behavior. Presents a computer simulation that predicts behavior based on variables (effort and rewards) determined by the invariable (desired reward). Argues that control theory methods better reflect relationships to…

Interval type-2 fuzzy PID controller for uncertain nonlinear inverted pendulum system.

PubMed

El-Bardini, Mohammad; El-Nagar, Ahmad M

2014-05-01

In this paper, the interval type-2 fuzzy proportional-integral-derivative controller (IT2F-PID) is proposed for controlling an inverted pendulum on a cart system with an uncertain model. The proposed controller is designed using a new method of type-reduction that we have proposed, which is called the simplified type-reduction method. The proposed IT2F-PID controller is able to handle the effect of structure uncertainties due to the structure of the interval type-2 fuzzy logic system (IT2-FLS). The results of the proposed IT2F-PID controller using a new method of type-reduction are compared with the other proposed IT2F-PID controller using the uncertainty bound method and the type-1 fuzzy PID controller (T1F-PID). The simulation and practical results show that the performance of the proposed controller is significantly improved compared with the T1F-PID controller. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

A Method for Implementing Force-Limited Vibration Control

NASA Technical Reports Server (NTRS)

Worth, Daniel B.

1997-01-01

NASA/GSFC has implemented force-limited vibration control on a controller which can only accept one profile. The method uses a personal computer based digital signal processing board to convert force and/or moment signals into what appears to he an acceleration signal to the controller. This technique allows test centers with older controllers to use the latest force-limited control techniques for random vibration testing. The paper describes the method, hardware, and test procedures used. An example from a test performed at NASA/GSFC is used as a guide.

Vibration suppression of planar truss structures utilizing uniform damping control

NASA Technical Reports Server (NTRS)

Andersen, G. C.; Silverberg, L. M.

1986-01-01

A variety of methods has been devised for vibrational control of a structure using both passive and active controls. Presented in this paper is a relatively new method for vibration suppression, uniform damping control. This method consists of implementing a control law which tends to dampen each vibrational mode of the structure at the same desirable exponential rate. The unique aspects of this method are that the control law is not explicitly dependent on the structural stiffness, the control forces are directly proportional to the distribution of the structural mass, and the control law is natural and decentralized. The control law was applied to a flexible planar truss structure and the various aspects of implementation of the control law examined are: actuator/sensor number, placement, and the impact of the actuator/sensor number and placement on the necessary control 'power' requirements such as peak power loads, total power requirements, etc. Also examined are the effects of using a limited number of active members in terms of the vibrational performance when compared with the 'ideal' distributed control law.

Using block pulse functions for seismic vibration semi-active control of structures with MR dampers

NASA Astrophysics Data System (ADS)

Rahimi Gendeshmin, Saeed; Davarnia, Daniel

2018-03-01

This article applied the idea of block pulse functions in the semi-active control of structures. The BP functions give effective tools to approximate complex problems. The applied control algorithm has a major effect on the performance of the controlled system and the requirements of the control devices. In control problems, it is important to devise an accurate analytical technique with less computational cost. It is proved that the BP functions are fundamental tools in approximation problems which have been applied in disparate areas in last decades. This study focuses on the employment of BP functions in control algorithm concerning reduction the computational cost. Magneto-rheological (MR) dampers are one of the well-known semi-active tools that can be used to control the response of civil Structures during earthquake. For validation purposes, numerical simulations of a 5-story shear building frame with MR dampers are presented. The results of suggested method were compared with results obtained by controlling the frame by the optimal control method based on linear quadratic regulator theory. It can be seen from simulation results that the suggested method can be helpful in reducing seismic structural responses. Besides, this method has acceptable accuracy and is in agreement with optimal control method with less computational costs.

Systematic methods for the design of a class of fuzzy logic controllers

NASA Astrophysics Data System (ADS)

Yasin, Saad Yaser

2002-09-01

Fuzzy logic control, a relatively new branch of control, can be used effectively whenever conventional control techniques become inapplicable or impractical. Various attempts have been made to create a generalized fuzzy control system and to formulate an analytically based fuzzy control law. In this study, two methods, the left and right parameterization method and the normalized spline-base membership function method, were utilized for formulating analytical fuzzy control laws in important practical control applications. The first model was used to design an idle speed controller, while the second was used to control an inverted control problem. The results of both showed that a fuzzy logic control system based on the developed models could be used effectively to control highly nonlinear and complex systems. This study also investigated the application of fuzzy control in areas not fully utilizing fuzzy logic control. Three important practical applications pertaining to the automotive industries were studied. The first automotive-related application was the idle speed of spark ignition engines, using two fuzzy control methods: (1) left and right parameterization, and (2) fuzzy clustering techniques and experimental data. The simulation and experimental results showed that a conventional controller-like performance fuzzy controller could be designed based only on experimental data and intuitive knowledge of the system. In the second application, the automotive cruise control problem, a fuzzy control model was developed using parameters adaptive Proportional plus Integral plus Derivative (PID)-type fuzzy logic controller. Results were comparable to those using linearized conventional PID and linear quadratic regulator (LQR) controllers and, in certain cases and conditions, the developed controller outperformed the conventional PID and LQR controllers. The third application involved the air/fuel ratio control problem, using fuzzy clustering techniques, experimental data, and a conversion algorithm, to develop a fuzzy-based control algorithm. Results were similar to those obtained by recently published conventional control based studies. The influence of the fuzzy inference operators and parameters on performance and stability of the fuzzy logic controller was studied Results indicated that, the selections of certain parameters or combinations of parameters, affect greatly the performance and stability of the fuzzy controller. Diagnostic guidelines used to tune or change certain factors or parameters to improve controller performance were developed based on knowledge gained from conventional control methods and knowledge gained from the experimental and the simulation results of this study.

Simulation and Experimental Investigation of Structural Dynamic Frequency Characteristics Control

PubMed Central

Zhang, Xingwu; Chen, Xuefeng; You, Shangqin; He, Zhengjia; Li, Bing

2012-01-01

In general, mechanical equipment such as cars, airplanes, and machine tools all operate with constant frequency characteristics. These constant working characteristics should be controlled if the dynamic performance of the equipment demands improvement or the dynamic characteristics is intended to change with different working conditions. Active control is a stable and beneficial method for this, but current active control methods mainly focus on vibration control for reducing the vibration amplitudes in the time domain or frequency domain. In this paper, a new method of dynamic frequency characteristics active control (DFCAC) is presented for a flat plate, which can not only accomplish vibration control but also arbitrarily change the dynamic characteristics of the equipment. The proposed DFCAC algorithm is based on a neural network including two parts of the identification implement and the controller. The effectiveness of the DFCAC method is verified by several simulation and experiments, which provide desirable results. PMID:22666072

Simulation and experimental investigation of structural dynamic frequency characteristics control.

PubMed

Zhang, Xingwu; Chen, Xuefeng; You, Shangqin; He, Zhengjia; Li, Bing

2012-01-01

In general, mechanical equipment such as cars, airplanes, and machine tools all operate with constant frequency characteristics. These constant working characteristics should be controlled if the dynamic performance of the equipment demands improvement or the dynamic characteristics is intended to change with different working conditions. Active control is a stable and beneficial method for this, but current active control methods mainly focus on vibration control for reducing the vibration amplitudes in the time domain or frequency domain. In this paper, a new method of dynamic frequency characteristics active control (DFCAC) is presented for a flat plate, which can not only accomplish vibration control but also arbitrarily change the dynamic characteristics of the equipment. The proposed DFCAC algorithm is based on a neural network including two parts of the identification implement and the controller. The effectiveness of the DFCAC method is verified by several simulation and experiments, which provide desirable results.

Progress in multirate digital control system design

NASA Technical Reports Server (NTRS)

Berg, Martin C.; Mason, Gregory S.

1991-01-01

A new methodology for multirate sampled-data control design based on a new generalized control law structure, two new parameter-optimization-based control law synthesis methods, and a new singular-value-based robustness analysis method are described. The control law structure can represent multirate sampled-data control laws of arbitrary structure and dynamic order, with arbitrarily prescribed sampling rates for all sensors and update rates for all processor states and actuators. The two control law synthesis methods employ numerical optimization to determine values for the control law parameters. The robustness analysis method is based on the multivariable Nyquist criterion applied to the loop transfer function for the sampling period equal to the period of repetition of the system's complete sampling/update schedule. The complete methodology is demonstrated by application to the design of a combination yaw damper and modal suppression system for a commercial aircraft.

An Experimental Comparison of Two Methods Of Teaching Numerical Control Manual Programming Concepts; Visual Media Versus Hands-On Equipment.

ERIC Educational Resources Information Center

Biekert, Russell

Accompanying the rapid changes in technology has been a greater dependence on automation and numerical control, which has resulted in the need to find ways of preparing programers for industrial machines using numerical control. To compare the hands-on equipment method and a visual media method of teaching numerical control, an experimental and a…

Computationally efficient control allocation

NASA Technical Reports Server (NTRS)

Durham, Wayne (Inventor)

2001-01-01

A computationally efficient method for calculating near-optimal solutions to the three-objective, linear control allocation problem is disclosed. The control allocation problem is that of distributing the effort of redundant control effectors to achieve some desired set of objectives. The problem is deemed linear if control effectiveness is affine with respect to the individual control effectors. The optimal solution is that which exploits the collective maximum capability of the effectors within their individual physical limits. Computational efficiency is measured by the number of floating-point operations required for solution. The method presented returned optimal solutions in more than 90% of the cases examined; non-optimal solutions returned by the method were typically much less than 1% different from optimal and the errors tended to become smaller than 0.01% as the number of controls was increased. The magnitude of the errors returned by the present method was much smaller than those that resulted from either pseudo inverse or cascaded generalized inverse solutions. The computational complexity of the method presented varied linearly with increasing numbers of controls; the number of required floating point operations increased from 5.5 i, to seven times faster than did the minimum-norm solution (the pseudoinverse), and at about the same rate as did the cascaded generalized inverse solution. The computational requirements of the method presented were much better than that of previously described facet-searching methods which increase in proportion to the square of the number of controls.

Sensorless Sinusoidal Drives for Fan and Pump Motors by V/f Control

NASA Astrophysics Data System (ADS)

Kiuchi, Mitsuyuki; Ohnishi, Tokuo

This paper proposes sensorless sinusoidal driving methods of permanent magnet synchronous motors for fans and pumps by V/f control. The proposed methods are simple methods that control the motor peak current constant by voltage or frequency control, and are characterized by DC link current detection using a single shunt resistor at carrier wave signal bottom timing. As a result of the dumping factor from square torque load characteristics of fan and pump motors, it is possible to control stable starting and stable steady state by V/f control. In general, pressure losses as a result of the fluid pass of fan and pump systems are nearly constant; therefore, the flow rate and motor torque are determined by revolutions. Accordingly, high efficiency driving is possible by setting corresponding currents to q-axis currents (torque currents) at target revolutions. Because of the simple current detection and motor control methods, the proposed methods are optimum for fan and pump motor driving systems of home appliances.

Multirate sampled-data yaw-damper and modal suppression system design

NASA Technical Reports Server (NTRS)

Berg, Martin C.; Mason, Gregory S.

1990-01-01

A multirate control law synthesized algorithm based on an infinite-time quadratic cost function, was developed along with a method for analyzing the robustness of multirate systems. A generalized multirate sampled-data control law structure (GMCLS) was introduced. A new infinite-time-based parameter optimization multirate sampled-data control law synthesis method and solution algorithm were developed. A singular-value-based method for determining gain and phase margins for multirate systems was also developed. The finite-time-based parameter optimization multirate sampled-data control law synthesis algorithm originally intended to be applied to the aircraft problem was instead demonstrated by application to a simpler problem involving the control of the tip position of a two-link robot arm. The GMCLS, the infinite-time-based parameter optimization multirate control law synthesis method and solution algorithm, and the singular-value based method for determining gain and phase margins were all demonstrated by application to the aircraft control problem originally proposed for this project.

Multidisciplinary optimization of a controlled space structure using 150 design variables

NASA Technical Reports Server (NTRS)

James, Benjamin B.

1992-01-01

A general optimization-based method for the design of large space platforms through integration of the disciplines of structural dynamics and control is presented. The method uses the global sensitivity equations approach and is especially appropriate for preliminary design problems in which the structural and control analyses are tightly coupled. The method is capable of coordinating general purpose structural analysis, multivariable control, and optimization codes, and thus, can be adapted to a variety of controls-structures integrated design projects. The method is used to minimize the total weight of a space platform while maintaining a specified vibration decay rate after slewing maneuvers.

Active controls: A look at analytical methods and associated tools

NASA Technical Reports Server (NTRS)

Newsom, J. R.; Adams, W. M., Jr.; Mukhopadhyay, V.; Tiffany, S. H.; Abel, I.

1984-01-01

A review of analytical methods and associated tools for active controls analysis and design problems is presented. Approaches employed to develop mathematical models suitable for control system analysis and/or design are discussed. Significant efforts have been expended to develop tools to generate the models from the standpoint of control system designers' needs and develop the tools necessary to analyze and design active control systems. Representative examples of these tools are discussed. Examples where results from the methods and tools have been compared with experimental data are also presented. Finally, a perspective on future trends in analysis and design methods is presented.

Some Modeling Tools Available for Adaptive Management of South Florida Hydrology

NASA Astrophysics Data System (ADS)

Lal, W. A.; Van Zee, R. J.

2002-05-01

The hydrology of South Florida is a result of (1) the hydrology of the natural system; (2) the hydrology of the man made design components such as structures and levees designed to alter the natural hydrology; (3) influence of the operations imposed on the system using the design components. Successful restoration of the South Florida ecosystem depend not only on the design of the structural components, but also on its careful operation. The current discussion is focused on a number of optimal control methods that have recently become available to optimize restoration goals in the context of modeling. Optimal operation of the system can lessen stresses on some hydrological and ecological components. Careless operation can on the other hand lead to disastrous effects. Systems engineering and control theory have been used in the past to understand and operate simple systems such as the cruise control and the thermostat. Somewhat complex ones have been used to auto-pilot planes. The simplest control methods such as proportional and integral (PI) control are already used in the South Florida Water Management Model (SFWMM) for flood control and rain driven operations. The popular proportional-integral-differential (PID) control is widely used in industry for operational control of complex engineering systems. Some uses of PID control are investigated in the study. Other methods that an be used for operational control include Baysean methods, Kalman filtering and Neural network methods. A cursory evaluation of these methods is made in the discussion, along with the traditional methods used to operate complex engineering systems.

PID self tuning control based on Mamdani fuzzy logic control for quadrotor stabilization

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

Priyambodo, Tri Kuntoro, E-mail: mastri@ugm.ac.id; Putra, Agfianto Eko; Department of Computer Science and Electronics, Universitas Gadjah Mada, Yogyakarta

Quadrotor as one type of UAV have the ability to perform Vertical Take Off and Landing (VTOL). It allows the Quadrotor to be stationary hovering in the air. PID (Proportional Integral Derivative) control system is one of the control methods that are commonly used. It is usually used to optimize the Quadrotor stabilization at least based on the three Eulerian angles (roll, pitch, and yaw) as input parameters for the control system. The three constants of PID can be obtained in various methods. The simplest method is tuning manually. This method has several weaknesses. For example if the three constantsmore » are not exact, the resulting response will deviate from the desired result. By combining the methods of PID with fuzzy logic systems where human expertise is implemented into the machine language is expected to further optimize the control system.« less

Simulation Research on Vehicle Active Suspension Controller Based on G1 Method

NASA Astrophysics Data System (ADS)

Li, Gen; Li, Hang; Zhang, Shuaiyang; Luo, Qiuhui

2017-09-01

Based on the order relation analysis method (G1 method), the optimal linear controller of vehicle active suspension is designed. The system of the main and passive suspension of the single wheel vehicle is modeled and the system input signal model is determined. Secondly, the system motion state space equation is established by the kinetic knowledge and the optimal linear controller design is completed with the optimal control theory. The weighting coefficient of the performance index coefficients of the main passive suspension is determined by the relational analysis method. Finally, the model is simulated in Simulink. The simulation results show that: the optimal weight value is determined by using the sequence relation analysis method under the condition of given road conditions, and the vehicle acceleration, suspension stroke and tire motion displacement are optimized to improve the comprehensive performance of the vehicle, and the active control is controlled within the requirements.

Application of laser chaos control methods to controlling thyroid-catatonic oscillations and burst firing of dopamine neurons

NASA Astrophysics Data System (ADS)

Duong-van, Minh

1993-11-01

A method of controlling chaotic to laminar flows in the Lorenz equations using fixed points dictated by minimizing the Lyapunov functional was proposed by Singer, Wang and Bau. Using different fixed points, we find that the solutions in a chaotic regime can also be periodic. Since the lasers equations are isomorphic to the Lorenz equations, we use this new method to control chaos when the laser is operated over the pump threshold. Furthermore, by solving the laser equations with an occasional proportional feedback mechanism, we recover the essential lasers controlling features experimentally discovered by Roy, Murphy, Jr., Maier, Gills and Hunt. This method of control chaos is now extended to various medical and biological systems.

The application of quadratic optimal cooperative control synthesis to a CH-47 helicopter

NASA Technical Reports Server (NTRS)

Townsend, Barbara K.

1987-01-01

A control-system design method, quadratic optimal cooperative control synthesis (CCS), is applied to the design of a stability and control augmentation system (SCAS). The CCS design method is different from other design methods in that it does not require detailed a priori design criteria, but instead relies on an explicit optimal pilot-model to create desired performance. The design method, which was developed previously for fixed-wing aircraft, is simplified and modified for application to a Boeing CH-47 helicopter. Two SCAS designs are developed using the CCS design methodology. The resulting CCS designs are then compared with designs obtained using classical/frequency-domain methods and linear quadratic regulator (LQR) theory in a piloted fixed-base simulation. Results indicate that the CCS method, with slight modifications, can be used to produce controller designs which compare favorably with the frequency-domain approach.

Space station contamination control study: Internal combustion, phase 1

NASA Technical Reports Server (NTRS)

Ruggeri, Robert T.

1987-01-01

Contamination inside Space Station modules was studied to determine the best methods of controlling contamination. The work was conducted in five tasks that identified existing contamination control requirements, analyzed contamination levels, developed outgassing specification for materials, wrote a contamination control plan, and evaluated current materials of offgassing tests used by NASA. It is concluded that current contamination control methods can be made to function on the Space Station for up to 1000 days, but that current methods are deficient for periods longer than about 1000 days.

A method to stabilize linear systems using eigenvalue gradient information

NASA Technical Reports Server (NTRS)

Wieseman, C. D.

1985-01-01

Formal optimization methods and eigenvalue gradient information are used to develop a stabilizing control law for a closed loop linear system that is initially unstable. The method was originally formulated by using direct, constrained optimization methods with the constraints being the real parts of the eigenvalues. However, because of problems in trying to achieve stabilizing control laws, the problem was reformulated to be solved differently. The method described uses the Davidon-Fletcher-Powell minimization technique to solve an indirect, constrained minimization problem in which the performance index is the Kreisselmeier-Steinhauser function of the real parts of all the eigenvalues. The method is applied successfully to solve two different problems: the determination of a fourth-order control law stabilizes a single-input single-output active flutter suppression system and the determination of a second-order control law for a multi-input multi-output lateral-directional flight control system. Various sets of design variables and initial starting points were chosen to show the robustness of the method.

Hierarchical Shared Control of Cane-Type Walking-Aid Robot

PubMed Central

Tao, Chunjing

2017-01-01

A hierarchical shared-control method of the walking-aid robot for both human motion intention recognition and the obstacle emergency-avoidance method based on artificial potential field (APF) is proposed in this paper. The human motion intention is obtained from the interaction force measurements of the sensory system composed of 4 force-sensing registers (FSR) and a torque sensor. Meanwhile, a laser-range finder (LRF) forward is applied to detect the obstacles and try to guide the operator based on the repulsion force calculated by artificial potential field. An obstacle emergency-avoidance method which comprises different control strategies is also assumed according to the different states of obstacles or emergency cases. To ensure the user's safety, the hierarchical shared-control method combines the intention recognition method with the obstacle emergency-avoidance method based on the distance between the walking-aid robot and the obstacles. At last, experiments validate the effectiveness of the proposed hierarchical shared-control method. PMID:29093805

Online automatic tuning and control for fed-batch cultivation

PubMed Central

van Straten, Gerrit; van der Pol, Leo A.; van Boxtel, Anton J. B.

2007-01-01

Performance of controllers applied in biotechnological production is often below expectation. Online automatic tuning has the capability to improve control performance by adjusting control parameters. This work presents automatic tuning approaches for model reference specific growth rate control during fed-batch cultivation. The approaches are direct methods that use the error between observed specific growth rate and its set point; systematic perturbations of the cultivation are not necessary. Two automatic tuning methods proved to be efficient, in which the adaptation rate is based on a combination of the error, squared error and integral error. These methods are relatively simple and robust against disturbances, parameter uncertainties, and initialization errors. Application of the specific growth rate controller yields a stable system. The controller and automatic tuning methods are qualified by simulations and laboratory experiments with Bordetella pertussis. PMID:18157554

Advances in Adaptive Control Methods

NASA Technical Reports Server (NTRS)

Nguyen, Nhan

2009-01-01

This poster presentation describes recent advances in adaptive control technology developed by NASA. Optimal Control Modification is a novel adaptive law that can improve performance and robustness of adaptive control systems. A new technique has been developed to provide an analytical method for computing time delay stability margin for adaptive control systems.

Methods to Control EMI Noises Produced in Power Converter Systems

NASA Astrophysics Data System (ADS)

Mutoh, Nobuyoshi; Ogata, Mitukatu

A new method to control EMI noises produced in power converters (rectifier and inverter) composed of IPMs (Intelligent Power Modules) is studied especially focusing on differential mode noises. The differential mode noises are occurred due to switching operations of the PWM control. As they are diffused into the ground through stray capacitors distributed between the ground and the power transmission lines and machine frames, differential mode noises should be confined and suppressed within the smallest area where power converters are laid out. It is impossible to control differential mode noises easily occurring diffusion by the conventional methods like filtering techniques. So, a new EMI noise control method using a multi-power circuit technique is proposed. The proposed method of the effectiveness has been verified through simulations and experiments.

Hybrid Adaptive Flight Control with Model Inversion Adaptation

NASA Technical Reports Server (NTRS)

Nguyen, Nhan

2011-01-01

This study investigates a hybrid adaptive flight control method as a design possibility for a flight control system that can enable an effective adaptation strategy to deal with off-nominal flight conditions. The hybrid adaptive control blends both direct and indirect adaptive control in a model inversion flight control architecture. The blending of both direct and indirect adaptive control provides a much more flexible and effective adaptive flight control architecture than that with either direct or indirect adaptive control alone. The indirect adaptive control is used to update the model inversion controller by an on-line parameter estimation of uncertain plant dynamics based on two methods. The first parameter estimation method is an indirect adaptive law based on the Lyapunov theory, and the second method is a recursive least-squares indirect adaptive law. The model inversion controller is therefore made to adapt to changes in the plant dynamics due to uncertainty. As a result, the modeling error is reduced that directly leads to a decrease in the tracking error. In conjunction with the indirect adaptive control that updates the model inversion controller, a direct adaptive control is implemented as an augmented command to further reduce any residual tracking error that is not entirely eliminated by the indirect adaptive control.

Field-based random sampling without a sampling frame: control selection for a case-control study in rural Africa.

PubMed

Crampin, A C; Mwinuka, V; Malema, S S; Glynn, J R; Fine, P E

2001-01-01

Selection bias, particularly of controls, is common in case-control studies and may materially affect the results. Methods of control selection should be tailored both for the risk factors and disease under investigation and for the population being studied. We present here a control selection method devised for a case-control study of tuberculosis in rural Africa (Karonga, northern Malawi) that selects an age/sex frequency-matched random sample of the population, with a geographical distribution in proportion to the population density. We also present an audit of the selection process, and discuss the potential of this method in other settings.

Determining and understanding the control of flux. An illustration in submitochondrial particles of how to validate schemes of metabolic control.

PubMed

Moreno-Sánchez, R; Bravo, C; Westerhoff, H V

1999-09-01

Two complementary methods were used to determine how the rate of respiration and that of ATP hydrolysis were controlled in rat liver submitochondrial particles. In the first, 'direct control analysis' method, respiration was titrated with malonate, antimycin or cyanide at 20, 30 and 37 degrees C, to determine the flux control exerted by succinate dehydrogenase, cytochrome bc1 complex and cytochrome c oxidase, respectively. Together, the three respiratory complexes only controlled the flux by about 50%, leaving the other 50% of flux control to the H+ leak. In the second, 'elasticity based' method, the elasticity coefficients of the respiratory chain or the H+-ATPase and the H+ leak towards the H+ gradient were determined. Then, the flux control coefficients were calculated using the connectivity and summation laws of metabolic control theory. The correspondence between the flux control coefficients determined in the two ways validated the two methods. This allowed us to use the second method to analyse what was the kinetic origin of the observed distribution of control. Control of ATP hydrolysis by the ATPase decreased with increasing ATPase activity; hence, the control exerted by the H+ leak increased with increasing ATPase activity, due to a diminishing elasticity towards the H+ gradient. Reverse electron transport was mainly controlled by the ATPase; the sum of flux control coefficients of succinate dehydrogenase, NADH-CoQ oxidoreductase, and H+-ATPase yielded a value greater than one, indicating that the H+ leak exerted a significant negative control on this pathway.

Feedback control methods for drug dosage optimisation. Concepts, classification and clinical application.

PubMed

Vozeh, S; Steimer, J L

1985-01-01

The concept of feedback control methods for drug dosage optimisation is described from the viewpoint of control theory. The control system consists of 5 parts: (a) patient (the controlled process); (b) response (the measured feedback); (c) model (the mathematical description of the process); (d) adaptor (to update the parameters); and (e) controller (to determine optimum dosing strategy). In addition to the conventional distinction between open-loop and closed-loop control systems, a classification is proposed for dosage optimisation techniques which distinguishes between tight-loop and loose-loop methods depending on whether physician's interaction is absent or included as part of the control step. Unlike engineering problems where the process can usually be controlled by fully automated devices, therapeutic situations often require that the physician be included in the decision-making process to determine the 'optimal' dosing strategy. Tight-loop and loose-loop methods can be further divided into adaptive and non-adaptive, depending on the presence of the adaptor. The main application areas of tight-loop feedback control methods are general anaesthesia, control of blood pressure, and insulin delivery devices. Loose-loop feedback methods have been used for oral anticoagulation and in therapeutic drug monitoring. The methodology, advantages and limitations of the different approaches are reviewed. A general feature common to all application areas could be observed: to perform well under routine clinical conditions, which are characterised by large interpatient variability and sometimes also intrapatient changes, control systems should be adaptive. Apart from application in routine drug treatment, feedback control methods represent an important research tool. They can be applied for the investigation of pathophysiological and pharmacodynamic processes. A most promising application is the evaluation of the relationship between an intermediate response (e.g. drug level), which is often used as feedback for dosage adjustment, and the final therapeutic goal.

A novel vibration measurement and active control method for a hinged flexible two-connected piezoelectric plate

NASA Astrophysics Data System (ADS)

Qiu, Zhi-cheng; Wang, Xian-feng; Zhang, Xian-Min; Liu, Jin-guo

2018-07-01

A novel non-contact vibration measurement method using binocular vision sensors is proposed for piezoelectric flexible hinged plate. Decoupling methods of the bending and torsional low frequency vibration on measurement and driving control are investigated, using binocular vision sensors and piezoelectric actuators. A radial basis function neural network controller (RBFNNC) is designed to suppress both the larger and the smaller amplitude vibrations. To verify the non-contact measurement method and the designed controller, an experimental setup of the flexible hinged plate with binocular vision is constructed. Experiments on vibration measurement and control are conducted by using binocular vision sensors and the designed RBFNNC controllers, compared with the classical proportional and derivative (PD) control algorithm. The experimental measurement results demonstrate that the binocular vision sensors can detect the low-frequency bending and torsional vibration effectively. Furthermore, the designed RBF can suppress the bending vibration more quickly than the designed PD controller owing to the adjustment of the RBF control, especially for the small amplitude residual vibrations.

A data driven control method for structure vibration suppression

NASA Astrophysics Data System (ADS)

Xie, Yangmin; Wang, Chao; Shi, Hang; Shi, Junwei

2018-02-01

High radio-frequency space applications have motivated continuous research on vibration suppression of large space structures both in academia and industry. This paper introduces a novel data driven control method to suppress vibrations of flexible structures and experimentally validates the suppression performance. Unlike model-based control approaches, the data driven control method designs a controller directly from the input-output test data of the structure, without requiring parametric dynamics and hence free of system modeling. It utilizes the discrete frequency response via spectral analysis technique and formulates a non-convex optimization problem to obtain optimized controller parameters with a predefined controller structure. Such approach is then experimentally applied on an end-driving flexible beam-mass structure. The experiment results show that the presented method can achieve competitive disturbance rejections compared to a model-based mixed sensitivity controller under the same design criterion but with much less orders and design efforts, demonstrating the proposed data driven control is an effective approach for vibration suppression of flexible structures.

Optimal reorientation of asymmetric underactuated spacecraft using differential flatness and receding horizon control

NASA Astrophysics Data System (ADS)

Cai, Wei-wei; Yang, Le-ping; Zhu, Yan-wei

2015-01-01

This paper presents a novel method integrating nominal trajectory optimization and tracking for the reorientation control of an underactuated spacecraft with only two available control torque inputs. By employing a pseudo input along the uncontrolled axis, the flatness property of a general underactuated spacecraft is extended explicitly, by which the reorientation trajectory optimization problem is formulated into the flat output space with all the differential constraints eliminated. Ultimately, the flat output optimization problem is transformed into a nonlinear programming problem via the Chebyshev pseudospectral method, which is improved by the conformal map and barycentric rational interpolation techniques to overcome the side effects of the differential matrix's ill-conditions on numerical accuracy. Treating the trajectory tracking control as a state regulation problem, we develop a robust closed-loop tracking control law using the receding-horizon control method, and compute the feedback control at each control cycle rapidly via the differential transformation method. Numerical simulation results show that the proposed control scheme is feasible and effective for the reorientation maneuver.

Nanotextured Surfaces and Related Methods, Systems, and Uses

NASA Technical Reports Server (NTRS)

Greer, Harold F. (Inventor); Greer, Julia R. (Inventor)

2014-01-01

A method of controlling wetting characteristics is described. Such method includes forming and configuring nanostructures on a surface where controlling of the wetting characteristics is desired. Surfaces and methods of fabricating such surfaces are also described.

Robust backstepping control of an interlink converter in a hybrid AC/DC microgrid based on feedback linearisation method

NASA Astrophysics Data System (ADS)

Dehkordi, N. Mahdian; Sadati, N.; Hamzeh, M.

2017-09-01

This paper presents a robust dc-link voltage as well as a current control strategy for a bidirectional interlink converter (BIC) in a hybrid ac/dc microgrid. To enhance the dc-bus voltage control, conventional methods strive to measure and feedforward the load or source power in the dc-bus control scheme. However, the conventional feedforward-based approaches require remote measurement with communications. Moreover, conventional methods suffer from stability and performance issues, mainly due to the use of the small-signal-based control design method. To overcome these issues, in this paper, the power from DG units of the dc subgrid imposed on the BIC is considered an unmeasurable disturbance signal. In the proposed method, in contrast to existing methods, using the nonlinear model of BIC, a robust controller that does not need the remote measurement with communications effectively rejects the impact of the disturbance signal imposed on the BIC's dc-link voltage. To avoid communication links, the robust controller has a plug-and-play feature that makes it possible to add a DG/load to or remove it from the dc subgrid without distorting the hybrid microgrid stability. Finally, Monte Carlo simulations are conducted to confirm the effectiveness of the proposed control strategy in MATLAB/SimPowerSystems software environment.

Robust Economic Control Decision Method of Uncertain System on Urban Domestic Water Supply.

PubMed

Li, Kebai; Ma, Tianyi; Wei, Guo

2018-03-31

As China quickly urbanizes, urban domestic water generally presents the circumstances of both rising tendency and seasonal cycle fluctuation. A robust economic control decision method for dynamic uncertain systems is proposed in this paper. It is developed based on the internal model principle and pole allocation method, and it is applied to an urban domestic water supply system with rising tendency and seasonal cycle fluctuation. To achieve this goal, first a multiplicative model is used to describe the urban domestic water demand. Then, a capital stock and a labor stock are selected as the state vector, and the investment and labor are designed as the control vector. Next, the compensator subsystem is devised in light of the internal model principle. Finally, by using the state feedback control strategy and pole allocation method, the multivariable robust economic control decision method is implemented. The implementation with this model can accomplish the urban domestic water supply control goal, with the robustness for the variation of parameters. The methodology presented in this study may be applied to the water management system in other parts of the world, provided all data used in this study are available. The robust control decision method in this paper is also applicable to deal with tracking control problems as well as stabilization control problems of other general dynamic uncertain systems.

Robust Economic Control Decision Method of Uncertain System on Urban Domestic Water Supply

PubMed Central

Li, Kebai; Ma, Tianyi; Wei, Guo

2018-01-01

As China quickly urbanizes, urban domestic water generally presents the circumstances of both rising tendency and seasonal cycle fluctuation. A robust economic control decision method for dynamic uncertain systems is proposed in this paper. It is developed based on the internal model principle and pole allocation method, and it is applied to an urban domestic water supply system with rising tendency and seasonal cycle fluctuation. To achieve this goal, first a multiplicative model is used to describe the urban domestic water demand. Then, a capital stock and a labor stock are selected as the state vector, and the investment and labor are designed as the control vector. Next, the compensator subsystem is devised in light of the internal model principle. Finally, by using the state feedback control strategy and pole allocation method, the multivariable robust economic control decision method is implemented. The implementation with this model can accomplish the urban domestic water supply control goal, with the robustness for the variation of parameters. The methodology presented in this study may be applied to the water management system in other parts of the world, provided all data used in this study are available. The robust control decision method in this paper is also applicable to deal with tracking control problems as well as stabilization control problems of other general dynamic uncertain systems. PMID:29614749

Evaluation of Shiryaev-Roberts Procedure for On-line Environmental Radiation Monitoring

NASA Astrophysics Data System (ADS)

Watson, Mara Mae

An on-line radiation monitoring system that simultaneously concentrates and detects radioactivity is needed to detect an accidental leakage from a nuclear waste disposal facility or clandestine nuclear activity. Previous studies have shown that classical control chart methods can be applied to on-line radiation monitoring data to quickly detect these events as they occur; however, Bayesian control chart methods were not included in these studies. This work will evaluate the performance of a Bayesian control chart method, the Shiryaev-Roberts (SR) procedure, compared to classical control chart methods, Shewhart 3-sigma and cumulative sum (CUSUM), for use in on-line radiation monitoring of 99Tc in water using extractive scintillating resin. Measurements were collected by pumping solutions containing 0.1-5 Bq/L of 99Tc, as 99T cO4-, through a flow cell packed with extractive scintillating resin coupled to a Beta-RAM Model 5 HPLC detector. While 99T cO4- accumulated on the resin, simultaneous measurements were acquired in 10-s intervals and then re-binned to 100-s intervals. The Bayesian statistical method, Shiryaev-Roberts procedure, and classical control chart methods, Shewhart 3-sigma and cumulative sum (CUSUM), were applied to the data using statistical algorithms developed in MATLAB RTM. Two SR control charts were constructed using Poisson distributions and Gaussian distributions to estimate the likelihood ratio, and are referred to as Poisson SR and Gaussian SR to indicate the distribution used to calculate the statistic. The Poisson and Gaussian SR methods required as little as 28.9 mL less solution at 5 Bq/L and as much as 170 mL less solution at 0.5 Bq/L to exceed the control limit than the Shewhart 3-sigma method. The Poisson SR method needed as little as 6.20 mL less solution at 5 Bq/L and up to 125 mL less solution at 0.5 Bq/L to exceed the control limit than the CUSUM method. The Gaussian SR and CUSUM method required comparable solution volumes for test solutions containing at least 1.5 Bq/L of 99T c. For activity concentrations less than 1.5 Bq/L, the Gaussian SR method required as much as 40.8 mL less solution at 0.5 Bq/L to exceed the control limit than the CUSUM method. Both SR methods were able to consistently detect test solutions containing 0.1 Bq/L, unlike the Shewhart 3-sigma and CUSUM methods. Although the Poisson SR method required as much as 178 mL less solution to exceed the control limit than the Gaussian SR method, the Gaussian SR false positive of 0% was much lower than the Poisson SR false positive rate of 1.14%. A lower false positive rate made it easier to differentiate between a false positive and an increase in mean count rate caused by activity accumulating on the resin. The SR procedure is thus the ideal tool for low-level on-line radiation monitoring using extractive scintillating resin, because it needed less volume in most cases to detect an upward shift in the mean count rate than the Shewhart 3-sigma and CUSUM methods and consistently detected lower activity concentrations. The desired results for the monitoring scheme, however, need to be considered prior to choosing between the Poisson and Gaussian distribution to estimate the likelihood ratio, because each was advantageous under different circumstances. Once the control limit was exceeded, activity concentrations were estimated from the SR control chart using the slope of the control chart on a semi-logarithmic plot. Five of nine test solutions for the Poisson SR control chart produced concentration estimates within 30% of the actual value, but the worst case was 263.2% different than the actual value. The estimations for the Gaussian SR control chart were much more precise, with six of eight solutions producing estimates within 30%. Although the activity concentrations estimations were only mediocre for the Poisson SR control chart and satisfactory for the Gaussian SR control chart, these results demonstrate that a relationship exists between activity concentration and the SR control chart magnitude that can be exploited to determine the activity concentration from the SR control chart. More complex methods should be investigated to improve activity concentration estimations from the SR control charts.

Nonlinear Performance Seeking Control using Fuzzy Model Reference Learning Control and the Method of Steepest Descent

NASA Technical Reports Server (NTRS)

Kopasakis, George

1997-01-01

Performance Seeking Control (PSC) attempts to find and control the process at the operating condition that will generate maximum performance. In this paper a nonlinear multivariable PSC methodology will be developed, utilizing the Fuzzy Model Reference Learning Control (FMRLC) and the method of Steepest Descent or Gradient (SDG). This PSC control methodology employs the SDG method to find the operating condition that will generate maximum performance. This operating condition is in turn passed to the FMRLC controller as a set point for the control of the process. The conventional SDG algorithm is modified in this paper in order for convergence to occur monotonically. For the FMRLC control, the conventional fuzzy model reference learning control methodology is utilized, with guidelines generated here for effective tuning of the FMRLC controller.

Prediction of final error level in learning and repetitive control

NASA Astrophysics Data System (ADS)

Levoci, Peter A.

Repetitive control (RC) is a field that creates controllers to eliminate the effects of periodic disturbances on a feedback control system. The methods have applications in spacecraft problems, to isolate fine pointing equipment from periodic vibration disturbances such as slight imbalances in momentum wheels or cryogenic pumps. A closely related field of control design is iterative learning control (ILC) which aims to eliminate tracking error in a task that repeats, each time starting from the same initial condition. Experiments done on a robot at NASA Langley Research Center showed that the final error levels produced by different candidate repetitive and learning controllers can be very different, even when each controller is analytically proven to converge to zero error in the deterministic case. Real world plant and measurement noise and quantization noise (from analog to digital and digital to analog converters) in these control methods are acted on as if they were error sources that will repeat and should be cancelled, which implies that the algorithms amplify such errors. Methods are developed that predict the final error levels of general first order ILC, of higher order ILC including current cycle learning, and of general RC, in the presence of noise, using frequency response methods. The method involves much less computation than the corresponding time domain approach that involves large matrices. The time domain approach was previously developed for ILC and handles a certain class of ILC methods. Here methods are created to include zero-phase filtering that is very important in creating practical designs. Also, time domain methods are developed for higher order ILC and for repetitive control. Since RC and ILC must be implemented digitally, all of these methods predict final error levels at the sample times. It is shown here that RC can easily converge to small error levels between sample times, but that ILC in most applications will have large and diverging intersample error if in fact zero error is reached at the sample times. This is independent of the ILC law used, and is purely a property of the physical system. Methods are developed to address this issue.

A time-domain decomposition iterative method for the solution of distributed linear quadratic optimal control problems

NASA Astrophysics Data System (ADS)

Heinkenschloss, Matthias

2005-01-01

We study a class of time-domain decomposition-based methods for the numerical solution of large-scale linear quadratic optimal control problems. Our methods are based on a multiple shooting reformulation of the linear quadratic optimal control problem as a discrete-time optimal control (DTOC) problem. The optimality conditions for this DTOC problem lead to a linear block tridiagonal system. The diagonal blocks are invertible and are related to the original linear quadratic optimal control problem restricted to smaller time-subintervals. This motivates the application of block Gauss-Seidel (GS)-type methods for the solution of the block tridiagonal systems. Numerical experiments show that the spectral radii of the block GS iteration matrices are larger than one for typical applications, but that the eigenvalues of the iteration matrices decay to zero fast. Hence, while the GS method is not expected to convergence for typical applications, it can be effective as a preconditioner for Krylov-subspace methods. This is confirmed by our numerical tests.A byproduct of this research is the insight that certain instantaneous control techniques can be viewed as the application of one step of the forward block GS method applied to the DTOC optimality system.

Policy Gradient Adaptive Dynamic Programming for Data-Based Optimal Control.

PubMed

Luo, Biao; Liu, Derong; Wu, Huai-Ning; Wang, Ding; Lewis, Frank L

2017-10-01

The model-free optimal control problem of general discrete-time nonlinear systems is considered in this paper, and a data-based policy gradient adaptive dynamic programming (PGADP) algorithm is developed to design an adaptive optimal controller method. By using offline and online data rather than the mathematical system model, the PGADP algorithm improves control policy with a gradient descent scheme. The convergence of the PGADP algorithm is proved by demonstrating that the constructed Q -function sequence converges to the optimal Q -function. Based on the PGADP algorithm, the adaptive control method is developed with an actor-critic structure and the method of weighted residuals. Its convergence properties are analyzed, where the approximate Q -function converges to its optimum. Computer simulation results demonstrate the effectiveness of the PGADP-based adaptive control method.

Multiple model self-tuning control for a class of nonlinear systems

NASA Astrophysics Data System (ADS)

Huang, Miao; Wang, Xin; Wang, Zhenlei

2015-10-01

This study develops a novel nonlinear multiple model self-tuning control method for a class of nonlinear discrete-time systems. An increment system model and a modified robust adaptive law are proposed to expand the application range, thus eliminating the assumption that either the nonlinear term of the nonlinear system or its differential term is global-bounded. The nonlinear self-tuning control method can address the situation wherein the nonlinear system is not subject to a globally uniformly asymptotically stable zero dynamics by incorporating the pole-placement scheme. A novel, nonlinear control structure based on this scheme is presented to improve control precision. Stability and convergence can be confirmed when the proposed multiple model self-tuning control method is applied. Furthermore, simulation results demonstrate the effectiveness of the proposed method.

Model and controller reduction of large-scale structures based on projection methods

NASA Astrophysics Data System (ADS)

Gildin, Eduardo

The design of low-order controllers for high-order plants is a challenging problem theoretically as well as from a computational point of view. Frequently, robust controller design techniques result in high-order controllers. It is then interesting to achieve reduced-order models and controllers while maintaining robustness properties. Controller designed for large structures based on models obtained by finite element techniques yield large state-space dimensions. In this case, problems related to storage, accuracy and computational speed may arise. Thus, model reduction methods capable of addressing controller reduction problems are of primary importance to allow the practical applicability of advanced controller design methods for high-order systems. A challenging large-scale control problem that has emerged recently is the protection of civil structures, such as high-rise buildings and long-span bridges, from dynamic loadings such as earthquakes, high wind, heavy traffic, and deliberate attacks. Even though significant effort has been spent in the application of control theory to the design of civil structures in order increase their safety and reliability, several challenging issues are open problems for real-time implementation. This dissertation addresses with the development of methodologies for controller reduction for real-time implementation in seismic protection of civil structures using projection methods. Three classes of schemes are analyzed for model and controller reduction: nodal truncation, singular value decomposition methods and Krylov-based methods. A family of benchmark problems for structural control are used as a framework for a comparative study of model and controller reduction techniques. It is shown that classical model and controller reduction techniques, such as balanced truncation, modal truncation and moment matching by Krylov techniques, yield reduced-order controllers that do not guarantee stability of the closed-loop system, that is, the reduced-order controller implemented with the full-order plant. A controller reduction approach is proposed such that to guarantee closed-loop stability. It is based on the concept of dissipativity (or positivity) of linear dynamical systems. Utilizing passivity preserving model reduction together with dissipative-LQG controllers, effective low-order optimal controllers are obtained. Results are shown through simulations.

Method for measuring and controlling beam current in ion beam processing

DOEpatents

Kearney, Patrick A.; Burkhart, Scott C.

2003-04-29

A method for producing film thickness control of ion beam sputter deposition films. Great improvements in film thickness control is accomplished by keeping the total current supplied to both the beam and suppressor grids of a radio frequency (RF) in beam source constant, rather than just the current supplied to the beam grid. By controlling both currents, using this method, deposition rates are more stable, and this allows the deposition of layers with extremely well controlled thicknesses to about 0.1%. The method is carried out by calculating deposition rates based on the total of the suppressor and beam currents and maintaining the total current constant by adjusting RF power which gives more consistent values.

Method for neural network control of motion using real-time environmental feedback

NASA Technical Reports Server (NTRS)

Buckley, Theresa M. (Inventor)

1997-01-01

A method of motion control for robotics and other automatically controlled machinery using a neural network controller with real-time environmental feedback. The method is illustrated with a two-finger robotic hand having proximity sensors and force sensors that provide environmental feedback signals. The neural network controller is taught to control the robotic hand through training sets using back- propagation methods. The training sets are created by recording the control signals and the feedback signal as the robotic hand or a simulation of the robotic hand is moved through a representative grasping motion. The data recorded is divided into discrete increments of time and the feedback data is shifted out of phase with the control signal data so that the feedback signal data lag one time increment behind the control signal data. The modified data is presented to the neural network controller as a training set. The time lag introduced into the data allows the neural network controller to account for the temporal component of the robotic motion. Thus trained, the neural network controlled robotic hand is able to grasp a wide variety of different objects by generalizing from the training sets.

Birth control - slow release methods

MedlinePlus

Contraception - slow-release hormonal methods; Progestin implants; Progestin injections; Skin patch; Vaginal ring ... might want to consider a different birth control method. SKIN PATCH The skin patch is placed on ...

33 CFR Appendix B to Part 273 - Information Requirements for Aquatic Plant Control Program Reports

Code of Federal Regulations, 2012 CFR

2012-07-01

... identification by common and scientific name of the plant or plants concerned, origin of infestation and likely... control operations or engineering works, including control methods, materials, equipment and procedures... operation control, the report should include a brief statement of the special problems in control methods...

33 CFR Appendix B to Part 273 - Information Requirements for Aquatic Plant Control Program Reports

Code of Federal Regulations, 2013 CFR

2013-07-01

... identification by common and scientific name of the plant or plants concerned, origin of infestation and likely... control operations or engineering works, including control methods, materials, equipment and procedures... operation control, the report should include a brief statement of the special problems in control methods...

Knowledge acquisition for a simple expert controller

NASA Technical Reports Server (NTRS)

Bieker, B.

1987-01-01

A method is presented for process control which has the properties of being incremental, cyclic and top-down. It is described on the basis of the development of an expert controller for a simple, but nonlinear control route. A quality comparison between expert controller and process operator shows the ability of the method for knowledge acquisition.

Method of making nanocrystalline alpha alumina

DOEpatents

Siegel, Richard W.; Hahn, Horst; Eastman, Jeffrey A.

1992-01-01

Method of making selected phases of nanocrystalline ceramic materials. Various methods of controlling the production of nanocrystalline alpha alumina and titanium oxygen phases are described. Control of the gas atmosphere and use of particular oxidation treatments give rise to the ability to control the particular phases provided in the aluminum/oxygen and titanium/oxygen system.

Pareto Design of State Feedback Tracking Control of a Biped Robot via Multiobjective PSO in Comparison with Sigma Method and Genetic Algorithms: Modified NSGAII and MATLAB's Toolbox

PubMed Central

Mahmoodabadi, M. J.; Taherkhorsandi, M.; Bagheri, A.

2014-01-01

An optimal robust state feedback tracking controller is introduced to control a biped robot. In the literature, the parameters of the controller are usually determined by a tedious trial and error process. To eliminate this process and design the parameters of the proposed controller, the multiobjective evolutionary algorithms, that is, the proposed method, modified NSGAII, Sigma method, and MATLAB's Toolbox MOGA, are employed in this study. Among the used evolutionary optimization algorithms to design the controller for biped robots, the proposed method operates better in the aspect of designing the controller since it provides ample opportunities for designers to choose the most appropriate point based upon the design criteria. Three points are chosen from the nondominated solutions of the obtained Pareto front based on two conflicting objective functions, that is, the normalized summation of angle errors and normalized summation of control effort. Obtained results elucidate the efficiency of the proposed controller in order to control a biped robot. PMID:24616619

Digital PI-PD controller design for arbitrary order systems: Dominant pole placement approach.

PubMed

Dincel, Emre; Söylemez, Mehmet Turan

2018-05-02

In this paper, a digital PI-PD controller design method is proposed for arbitrary order systems with or without time-delay to achieve desired transient response in the closed-loop via dominant pole placement approach. The digital PI-PD controller design problem is solved by converting the original problem to the digital PID controller design problem. Firstly, parametrization of the digital PID controllers which assign dominant poles to desired location is done. After that the subset of digital PID controller parameters in which the remaining poles are located away from the dominant pole pair is found via Chebyshev polynomials. The obtained PID controller parameters are then transformed into the PI-PD controller parameters by considering the closed-loop controller zero and the design is completed. Success of the proposed design method is firstly demonstrated on an example transfer function and compared with the well-known PID controller methods from the literature through simulations. After that the design method is implemented on the fan and plate laboratory system in a real environment. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Decentralized control of large flexible structures by joint decoupling

NASA Technical Reports Server (NTRS)

Su, Tzu-Jeng; Juang, Jer-Nan

1992-01-01

A decentralized control design method is presented for large complex flexible structures by using the idea of joint decoupling. The derivation is based on a coupled substructure state-space model, which is obtained from enforcing conditions of interface compatibility and equilibrium to the substructure state-space models. It is shown that by restricting the control law to be localized state feedback and by setting the joint actuator input commands to decouple joint 'degrees of freedom' (dof) from interior dof, the global structure control design problem can be decomposed into several substructure control design problems. The substructure control gains and substructure observers are designed based on modified substructure state-space models. The controllers produced by the proposed method can operate successfully at the individual substructure level as well as at the global structure level. Therefore, not only control design but also control implementation is decentralized. Stability and performance requirement of the closed-loop system can be achieved by using any existing state feedback control design method. A two-component mass-spring damper system and a three-truss structure are used as examples to demonstrate the proposed method.

PID Tuning Using Extremum Seeking

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

Killingsworth, N; Krstic, M

2005-11-15

Although proportional-integral-derivative (PID) controllers are widely used in the process industry, their effectiveness is often limited due to poor tuning. Manual tuning of PID controllers, which requires optimization of three parameters, is a time-consuming task. To remedy this difficulty, much effort has been invested in developing systematic tuning methods. Many of these methods rely on knowledge of the plant model or require special experiments to identify a suitable plant model. Reviews of these methods are given in [1] and the survey paper [2]. However, in many situations a plant model is not known, and it is not desirable to openmore » the process loop for system identification. Thus a method for tuning PID parameters within a closed-loop setting is advantageous. In relay feedback tuning [3]-[5], the feedback controller is temporarily replaced by a relay. Relay feedback causes most systems to oscillate, thus determining one point on the Nyquist diagram. Based on the location of this point, PID parameters can be chosen to give the closed-loop system a desired phase and gain margin. An alternative tuning method, which does not require either a modification of the system or a system model, is unfalsified control [6], [7]. This method uses input-output data to determine whether a set of PID parameters meets performance specifications. An adaptive algorithm is used to update the PID controller based on whether or not the controller falsifies a given criterion. The method requires a finite set of candidate PID controllers that must be initially specified [6]. Unfalsified control for an infinite set of PID controllers has been developed in [7]; this approach requires a carefully chosen input signal [8]. Yet another model-free PID tuning method that does not require opening of the loop is iterative feedback tuning (IFT). IFT iteratively optimizes the controller parameters with respect to a cost function derived from the output signal of the closed-loop system, see [9]. This method is based on the performance of the closed-loop system during a step response experiment [10], [11]. In this article we present a method for optimizing the step response of a closed-loop system consisting of a PID controller and an unknown plant with a discrete version of extremum seeking (ES). Specifically, ES is used to minimize a cost function similar to that used in [10], [11], which quantifies the performance of the PID controller. ES, a non-model-based method, iteratively modifies the arguments (in this application the PID parameters) of a cost function so that the output of the cost function reaches a local minimum or local maximum. In the next section we apply ES to PID controller tuning. We illustrate this technique through simulations comparing the effectiveness of ES to other PID tuning methods. Next, we address the importance of the choice of cost function and consider the effect of controller saturation. Furthermore, we discuss the choice of ES tuning parameters. Finally, we offer some conclusions.« less

Probabilistic Parameter Uncertainty Analysis of Single Input Single Output Control Systems

NASA Technical Reports Server (NTRS)

Smith, Brett A.; Kenny, Sean P.; Crespo, Luis G.

2005-01-01

The current standards for handling uncertainty in control systems use interval bounds for definition of the uncertain parameters. This approach gives no information about the likelihood of system performance, but simply gives the response bounds. When used in design, current methods of m-analysis and can lead to overly conservative controller design. With these methods, worst case conditions are weighted equally with the most likely conditions. This research explores a unique approach for probabilistic analysis of control systems. Current reliability methods are examined showing the strong areas of each in handling probability. A hybrid method is developed using these reliability tools for efficiently propagating probabilistic uncertainty through classical control analysis problems. The method developed is applied to classical response analysis as well as analysis methods that explore the effects of the uncertain parameters on stability and performance metrics. The benefits of using this hybrid approach for calculating the mean and variance of responses cumulative distribution functions are shown. Results of the probabilistic analysis of a missile pitch control system, and a non-collocated mass spring system, show the added information provided by this hybrid analysis.

Three-axis attitude control by two-step rotations using only magnetic torquers in a low Earth orbit near the magnetic equator

NASA Astrophysics Data System (ADS)

Inamori, Takaya; Otsuki, Kensuke; Sugawara, Yoshiki; Saisutjarit, Phongsatorn; Nakasuka, Shinichi

2016-11-01

This study proposes a novel method for three-axis attitude control using only magnetic torquers (MTQs). Previously, MTQs have been utilized for attitude control in many low Earth orbit satellites. Although MTQs are useful for achieving attitude control at low cost and high reliability without the need for propellant, these electromagnetic coils cannot be used to generate an attitude control torque about the geomagnetic field vector. Thus, conventional attitude control methods using MTQs assume the magnetic field changes in an orbital period so that the satellite can generate a required attitude control torque after waiting for a change in the magnetic field direction. However, in a near magnetic equatorial orbit, the magnetic field does not change in an inertial reference frame. Thus, satellites cannot generate a required attitude control torque in a single orbital period with only MTQs. This study proposes a method for achieving a rotation about the geomagnetic field vector by generating a torque that is perpendicular to it. First, this study shows that the three-axis attitude control using only MTQs is feasible with a two-step rotation. Then, the study proposes a method for controlling the attitude with the two-step rotation using a PD controller. Finally, the proposed method is assessed by examining the results of numerical simulations.

Self-optimizing Pitch Control for Large Scale Wind Turbine Based on ADRC

NASA Astrophysics Data System (ADS)

Xia, Anjun; Hu, Guoqing; Li, Zheng; Huang, Dongxiao; Wang, Fengxiang

2018-01-01

Since wind turbine is a complex nonlinear and strong coupling system, traditional PI control method can hardly achieve good control performance. A self-optimizing pitch control method based on the active-disturbance-rejection control theory is proposed in this paper. A linear model of the wind turbine is derived by linearizing the aerodynamic torque equation and the dynamic response of wind turbine is transformed into a first-order linear system. An expert system is designed to optimize the amplification coefficient according to the pitch rate and the speed deviation. The purpose of the proposed control method is to regulate the amplification coefficient automatically and keep the variations of pitch rate and rotor speed in proper ranges. Simulation results show that the proposed pitch control method has the ability to modify the amplification coefficient effectively, when it is not suitable, and keep the variations of pitch rate and rotor speed in proper ranges

Steering Law Controlling the Constant Speeds of Control Moment Gyros

NASA Astrophysics Data System (ADS)

KOYASAKO, Y.; TAKAHASHI, M.

2016-09-01

To enable the agile control of satellites, using control moment gyros (CMGs) has become increasingly necessary because of their ability to generate large amounts of torque. However, CMGs have a singularity problem whereby the torque by the CMGs degenerates from three dimensions to two dimensions, affecting spacecraft attitude control performance. This study proposes a new steering control law for CMGs by controlling the constant speed of a CMG. The proposed method enables agile attitude changes, according to the required task, by managing the total angular momentum of the CMGs by considering the distance to external singularities. In the proposed method, the total angular momentum is biased in a specific direction and the angular momentum envelope is extended. The design method can increase the net angular momentum of CMGs which can be exchanged with the satellite. The effectiveness of the proposed method is demonstrated by numerical simulations.

Classical Control System Design: A non-Graphical Method for Finding the Exact System Parameters

NASA Astrophysics Data System (ADS)

Hussein, Mohammed Tawfik

2008-06-01

The Root Locus method of control system design was developed in the 1940's. It is a set of rules that helps in sketching the path traced by the roots of the closed loop characteristic equation of the system, as a parameter such as a controller gain, k, is varied. The procedure provides approximate sketching guidelines. Designs on control systems using the method are therefore not exact. This paper aims at a non-graphical method for finding the exact system parameters to place a pair of complex conjugate poles on a specified damping ratio line. The overall procedure is based on the exact solution of complex equations on the PC using numerical methods.

A Model of Risk Analysis in Analytical Methodology for Biopharmaceutical Quality Control.

PubMed

Andrade, Cleyton Lage; Herrera, Miguel Angel De La O; Lemes, Elezer Monte Blanco

2018-01-01

One key quality control parameter for biopharmaceutical products is the analysis of residual cellular DNA. To determine small amounts of DNA (around 100 pg) that may be in a biologically derived drug substance, an analytical method should be sensitive, robust, reliable, and accurate. In principle, three techniques have the ability to measure residual cellular DNA: radioactive dot-blot, a type of hybridization; threshold analysis; and quantitative polymerase chain reaction. Quality risk management is a systematic process for evaluating, controlling, and reporting of risks that may affects method capabilities and supports a scientific and practical approach to decision making. This paper evaluates, by quality risk management, an alternative approach to assessing the performance risks associated with quality control methods used with biopharmaceuticals, using the tool hazard analysis and critical control points. This tool provides the possibility to find the steps in an analytical procedure with higher impact on method performance. By applying these principles to DNA analysis methods, we conclude that the radioactive dot-blot assay has the largest number of critical control points, followed by quantitative polymerase chain reaction, and threshold analysis. From the analysis of hazards (i.e., points of method failure) and the associated method procedure critical control points, we conclude that the analytical methodology with the lowest risk for performance failure for residual cellular DNA testing is quantitative polymerase chain reaction. LAY ABSTRACT: In order to mitigate the risk of adverse events by residual cellular DNA that is not completely cleared from downstream production processes, regulatory agencies have required the industry to guarantee a very low level of DNA in biologically derived pharmaceutical products. The technique historically used was radioactive blot hybridization. However, the technique is a challenging method to implement in a quality control laboratory: It is laborious, time consuming, semi-quantitative, and requires a radioisotope. Along with dot-blot hybridization, two alternatives techniques were evaluated: threshold analysis and quantitative polymerase chain reaction. Quality risk management tools were applied to compare the techniques, taking into account the uncertainties, the possibility of circumstances or future events, and their effects upon method performance. By illustrating the application of these tools with DNA methods, we provide an example of how they can be used to support a scientific and practical approach to decision making and can assess and manage method performance risk using such tools. This paper discusses, considering the principles of quality risk management, an additional approach to the development and selection of analytical quality control methods using the risk analysis tool hazard analysis and critical control points. This tool provides the possibility to find the method procedural steps with higher impact on method reliability (called critical control points). Our model concluded that the radioactive dot-blot assay has the larger number of critical control points, followed by quantitative polymerase chain reaction and threshold analysis. Quantitative polymerase chain reaction is shown to be the better alternative analytical methodology in residual cellular DNA analysis. © PDA, Inc. 2018.

Application of Sliding Mode Methods to the Design of Reconfigurable Flight Control Systems

NASA Technical Reports Server (NTRS)

Wells, Scott R.

2002-01-01

Observer-based sliding mode control is investigated for application to aircraft reconfigurable flight control. A comprehensive overview of reconfigurable flight control is given, including, a review of the current state-of-the-art within the subdisciplines of fault detection, parameter identification, adaptive control schemes, and dynamic control allocation. Of the adaptive control methods reviewed, sliding mode control (SMC) appears very promising due its property of invariance to matched uncertainty. An overview of sliding mode control is given and its remarkable properties are demonstrated by example. Sliding mode methods, however, are difficult to implement because unmodeled parasitic dynamics cause immediate and severe instability. This presents a challenge for all practical applications with limited bandwidth actuators. One method to deal with parasitic dynamics is the use of an asymptotic observer in the feedback path. Observer-based SMC is investigated, and a method for selecting observer gains is offered. An additional method for shaping the feedback loop using a filter is also developed. It is shown that this SMC prefilter is equivalent to a form of model reference hedging. A complete design procedure is given which takes advantage of the sliding mode boundary layer to recast the SMC as a linear control law. Frequency domain loop shaping is then used to design the sliding manifold. Finally, three aircraft applications are demonstrated. An F-18/HARV is used to demonstrate a SISO pitch rate tracking controller. It is also used to demonstrate a MIMO lateral-directional roll rate tracking controller. The last application is a full linear six degree-of-freedom advanced tailless fighter model. The observer-based SMC is seen to provide excellent tracking with superior robustness to parameter changes and actuator failures.

Research on frequency control strategy of interconnected region based on fuzzy PID

NASA Astrophysics Data System (ADS)

Zhang, Yan; Li, Chunlan

2018-05-01

In order to improve the frequency control performance of the interconnected power grid, overcome the problems of poor robustness and slow adjustment of traditional regulation, the paper puts forward a frequency control method based on fuzzy PID. The method takes the frequency deviation and tie-line deviation of each area as the control objective, takes the regional frequency deviation and its deviation as input, and uses fuzzy mathematics theory, adjusts PID control parameters online. By establishing the regional frequency control model of water-fire complementary power generation in MATLAB, the regional frequency control strategy is given, and three control modes (TBC-FTC, FTC-FTC, FFC-FTC) are simulated and analyzed. The simulation and experimental results show that, this method has better control performance compared with the traditional regional frequency regulation.

Quality Control Guidelines for SAM Chemical Methods

EPA Pesticide Factsheets

Learn more about quality control guidelines and recommendations for the analysis of samples using the chemistry methods listed in EPA's Selected Analytical Methods for Environmental Remediation and Recovery (SAM).

Quality Control Guidelines for SAM Pathogen Methods

EPA Pesticide Factsheets

Learn more about quality control guidelines and recommendations for the analysis of samples using the biotoxin methods listed in EPA's Selected Analytical Methods for Environmental Remediation and Recovery (SAM).

Quality Control Guidelines for SAM Radiochemical Methods

EPA Pesticide Factsheets

Learn more about quality control guidelines and recommendations for the analysis of samples using the radiochemistry methods listed in EPA's Selected Analytical Methods for Environmental Remediation and Recovery (SAM).

General Quality Control (QC) Guidelines for SAM Methods

EPA Pesticide Factsheets

Learn more about quality control guidelines and recommendations for the analysis of samples using the methods listed in EPA's Selected Analytical Methods for Environmental Remediation and Recovery (SAM).

Quality Control Guidelines for SAM Biotoxin Methods

EPA Pesticide Factsheets

Learn more about quality control guidelines and recommendations for the analysis of samples using the pathogen methods listed in EPA's Selected Analytical Methods for Environmental Remediation and Recovery (SAM).

Structured output-feedback controller synthesis with design specifications

NASA Astrophysics Data System (ADS)

Hao, Yuqing; Duan, Zhisheng

2017-03-01

This paper considers the problem of structured output-feedback controller synthesis with finite frequency specifications. Based on the orthogonal space information of input matrix, an improved parameter-dependent Lyapunov function method is first proposed. Then, a two-stage construction method is designed, which depends on an initial centralised controller. Corresponding design conditions for three types of output-feedback controllers are presented in terms of unified representations. Moreover, heuristic algorithms are provided to explore the desirable controllers. Finally, the effectiveness of these proposed methods is illustrated via some practical examples.

Adaptive identification and control of structural dynamics systems using recursive lattice filters

NASA Technical Reports Server (NTRS)

Sundararajan, N.; Montgomery, R. C.; Williams, J. P.

1985-01-01

A new approach for adaptive identification and control of structural dynamic systems by using least squares lattice filters thar are widely used in the signal processing area is presented. Testing procedures for interfacing the lattice filter identification methods and modal control method for stable closed loop adaptive control are presented. The methods are illustrated for a free-free beam and for a complex flexible grid, with the basic control objective being vibration suppression. The approach is validated by using both simulations and experimental facilities available at the Langley Research Center.

Report on an Overseas Visit in October/November 1986 to Review Maintenance Procedures for F404 Engine Electrical Control Unit and Related Matters

DTIC Science & Technology

1989-11-01

proposal for F404 control] DEEC Digital Electronic Engine Controller - first generation cf FADEC DMICS Design Methods for Integrated Control Systems...the aircraft configuration, but the method will not work with insufficient control power. Although some parameter, may vary by as much as 100 to I...34’red tie merits of ’similar n a d "dissimilar ’ redundancy, fault detection methods . sensor connections and representation ol tie svstenl ’ting con

Factorization and reduction methods for optimal control of distributed parameter systems

NASA Technical Reports Server (NTRS)

Burns, J. A.; Powers, R. K.

1985-01-01

A Chandrasekhar-type factorization method is applied to the linear-quadratic optimal control problem for distributed parameter systems. An aeroelastic control problem is used as a model example to demonstrate that if computationally efficient algorithms, such as those of Chandrasekhar-type, are combined with the special structure often available to a particular problem, then an abstract approximation theory developed for distributed parameter control theory becomes a viable method of solution. A numerical scheme based on averaging approximations is applied to hereditary control problems. Numerical examples are given.

Inertial Response of Wind Power Plants: A Comparison of Frequency-Based Inertial Control and Stepwise Inertial Control

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

Wang, Xiao; Gao, Wenzhong; Wang, Jianhui

The frequency regulation capability of a wind power plant plays an important role in enhancing frequency reliability especially in an isolated power system with high wind power penetration levels. A comparison of two types of inertial control methods, namely frequency-based inertial control (FBIC) and stepwise inertial control (SIC), is presented in this paper. Comprehensive case studies are carried out to reveal features of the different inertial control methods, simulated in a modified Western System Coordination Council (WSCC) nine-bus power grid using real-time digital simulator (RTDS) platform. The simulation results provide an insight into the inertial control methods under various scenarios.

Many tests of significance: new methods for controlling type I errors.

PubMed

Keselman, H J; Miller, Charles W; Holland, Burt

2011-12-01

There have been many discussions of how Type I errors should be controlled when many hypotheses are tested (e.g., all possible comparisons of means, correlations, proportions, the coefficients in hierarchical models, etc.). By and large, researchers have adopted familywise (FWER) control, though this practice certainly is not universal. Familywise control is intended to deal with the multiplicity issue of computing many tests of significance, yet such control is conservative--that is, less powerful--compared to per test/hypothesis control. The purpose of our article is to introduce the readership, particularly those readers familiar with issues related to controlling Type I errors when many tests of significance are computed, to newer methods that provide protection from the effects of multiple testing, yet are more powerful than familywise controlling methods. Specifically, we introduce a number of procedures that control the k-FWER. These methods--say, 2-FWER instead of 1-FWER (i.e., FWER)--are equivalent to specifying that the probability of 2 or more false rejections is controlled at .05, whereas FWER controls the probability of any (i.e., 1 or more) false rejections at .05. 2-FWER implicitly tolerates 1 false rejection and makes no explicit attempt to control the probability of its occurrence, unlike FWER, which tolerates no false rejections at all. More generally, k-FWER tolerates k - 1 false rejections, but controls the probability of k or more false rejections at α =.05. We demonstrate with two published data sets how more hypotheses can be rejected with k-FWER methods compared to FWER control.

ISS Contingency Attitude Control Recovery Method for Loss of Automatic Thruster Control

NASA Technical Reports Server (NTRS)

Bedrossian, Nazareth; Bhatt, Sagar; Alaniz, Abran; McCants, Edward; Nguyen, Louis; Chamitoff, Greg

2008-01-01

In this paper, the attitude control issues associated with International Space Station (ISS) loss of automatic thruster control capability are discussed and methods for attitude control recovery are presented. This scenario was experienced recently during Shuttle mission STS-117 and ISS Stage 13A in June 2007 when the Russian GN&C computers, which command the ISS thrusters, failed. Without automatic propulsive attitude control, the ISS would not be able to regain attitude control after the Orbiter undocked. The core issues associated with recovering long-term attitude control using CMGs are described as well as the systems engineering analysis to identify recovery options. It is shown that the recovery method can be separated into a procedure for rate damping to a safe harbor gravity gradient stable orientation and a capability to maneuver the vehicle to the necessary initial conditions for long term attitude hold. A manual control option using Soyuz and Progress vehicle thrusters is investigated for rate damping and maneuvers. The issues with implementing such an option are presented and the key issue of closed-loop stability is addressed. A new non-propulsive alternative to thruster control, Zero Propellant Maneuver (ZPM) attitude control method is introduced and its rate damping and maneuver performance evaluated. It is shown that ZPM can meet the tight attitude and rate error tolerances needed for long term attitude control. A combination of manual thruster rate damping to a safe harbor attitude followed by a ZPM to Stage long term attitude control orientation was selected by the Anomaly Resolution Team as the alternate attitude control method for such a contingency.

Inter-Vehicle Communication System Utilizing Autonomous Distributed Transmit Power Control

NASA Astrophysics Data System (ADS)

Hamada, Yuji; Sawa, Yoshitsugu; Goto, Yukio; Kumazawa, Hiroyuki

In ad-hoc network such as inter-vehicle communication (IVC) system, safety applications that vehicles broadcast the information such as car velocity, position and so on periodically are considered. In these applications, if there are many vehicles broadcast data in a communication area, congestion incurs a problem decreasing communication reliability. We propose autonomous distributed transmit power control method to keep high communication reliability. In this method, each vehicle controls its transmit power using feed back control. Furthermore, we design a communication protocol to realize the proposed method, and we evaluate the effectiveness of proposed method using computer simulation.

Method for controlling start-up and steady state performance of a closed split flow recompression brayton cycle

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

Pasch, James Jay

A method of resolving a balanced condition that generates control parameters for start-up and steady state operating points and various component and cycle performances for a closed split flow recompression cycle system. The method provides for improved control of a Brayton cycle thermal to electrical power conversion system. The method may also be used for system design, operational simulation and/or parameter prediction.

Nonlinear fractional order proportion-integral-derivative active disturbance rejection control method design for hypersonic vehicle attitude control

NASA Astrophysics Data System (ADS)

Song, Jia; Wang, Lun; Cai, Guobiao; Qi, Xiaoqiang

2015-06-01

Near space hypersonic vehicle model is nonlinear, multivariable and couples in the reentry process, which are challenging for the controller design. In this paper, a nonlinear fractional order proportion integral derivative (NFOPIλDμ) active disturbance rejection control (ADRC) strategy based on a natural selection particle swarm (NSPSO) algorithm is proposed for the hypersonic vehicle flight control. The NFOPIλDμ ADRC method consists of a tracking-differentiator (TD), an NFOPIλDμ controller and an extended state observer (ESO). The NFOPIλDμ controller designed by combining an FOPIλDμ method and a nonlinear states error feedback control law (NLSEF) is to overcome concussion caused by the NLSEF and conversely compensate the insufficiency for relatively simple and rough signal processing caused by the FOPIλDμ method. The TD is applied to coordinate the contradiction between rapidity and overshoot. By attributing all uncertain factors to unknown disturbances, the ESO can achieve dynamic feedback compensation for these disturbances and thus reduce their effects. Simulation results show that the NFOPIλDμ ADRC method can make the hypersonic vehicle six-degree-of-freedom nonlinear model track desired nominal signals accurately and fast, has good stability, dynamic properties and strong robustness against external environmental disturbances.

Closed loop statistical performance analysis of N-K knock controllers

NASA Astrophysics Data System (ADS)

Peyton Jones, James C.; Shayestehmanesh, Saeed; Frey, Jesse

2017-09-01

The closed loop performance of engine knock controllers cannot be rigorously assessed from single experiments or simulations because knock behaves as a random process and therefore the response belongs to a random distribution also. In this work a new method is proposed for computing the distributions and expected values of the closed loop response, both in steady state and in response to disturbances. The method takes as its input the control law, and the knock propensity characteristic of the engine which is mapped from open loop steady state tests. The method is applicable to the 'n-k' class of knock controllers in which the control action is a function only of the number of cycles n since the last control move, and the number k of knock events that have occurred in this time. A Cumulative Summation (CumSum) based controller falls within this category, and the method is used to investigate the performance of the controller in a deeper and more rigorous way than has previously been possible. The results are validated using onerous Monte Carlo simulations, which confirm both the validity of the method and its high computational efficiency.

Loop shaping design for tracking performance in machine axes.

PubMed

Schinstock, Dale E; Wei, Zhouhong; Yang, Tao

2006-01-01

A modern interpretation of classical loop shaping control design methods is presented in the context of tracking control for linear motor stages. Target applications include noncontacting machines such as laser cutters and markers, water jet cutters, and adhesive applicators. The methods are directly applicable to the common PID controller and are pertinent to many electromechanical servo actuators other than linear motors. In addition to explicit design techniques a PID tuning algorithm stressing the importance of tracking is described. While the theory behind these techniques is not new, the analysis of their application to modern systems is unique in the research literature. The techniques and results should be important to control practitioners optimizing PID controller designs for tracking and in comparing results from classical designs to modern techniques. The methods stress high-gain controller design and interpret what this means for PID. Nothing in the methods presented precludes the addition of feedforward control methods for added improvements in tracking. Laboratory results from a linear motor stage demonstrate that with large open-loop gain very good tracking performance can be achieved. The resultant tracking errors compare very favorably to results from similar motions on similar systems that utilize much more complicated controllers.

Sliding mode control method having terminal convergence in finite time

NASA Technical Reports Server (NTRS)

Venkataraman, Subramanian T. (Inventor); Gulati, Sandeep (Inventor)

1994-01-01

An object of this invention is to provide robust nonlinear controllers for robotic operations in unstructured environments based upon a new class of closed loop sliding control methods, sometimes denoted terminal sliders, where the new class will enforce closed-loop control convergence to equilibrium in finite time. Improved performance results from the elimination of high frequency control switching previously employed for robustness to parametric uncertainties. Improved performance also results from the dependence of terminal slider stability upon the rate of change of uncertainties over the sliding surface rather than the magnitude of the uncertainty itself for robust control. Terminal sliding mode control also yields improved convergence where convergence time is finite and is to be controlled. A further object is to apply terminal sliders to robot manipulator control and benchmark performance with the traditional computed torque control method and provide for design of control parameters.

Multi-axis control based on movement control cards in NC systems

NASA Astrophysics Data System (ADS)

Jiang, Tingbiao; Wei, Yunquan

2005-12-01

Today most movement control cards need special control software of topper computers and are only suitable for fixed-axis controls. Consequently, the number of axes which can be controlled is limited. Advanced manufacture technology develops at a very high speed, and that development brings forth. New requirements for movement control in mechanisms and electronics. This paper introduces products of the 5th generation of movement control cards, PMAC 2A-PC/104, made by the Delta Tau Company in the USA. Based on an analysis of PMAC 2A-PC/104, this paper first describes two aspects relevant to the hardware structure of movement control cards and the interrelated software of the topper computers. Then, two methods are presented for solving these problems. The first method is to set limit switches on the movement control cards; all of them can be used to control each moving axis. The second method is to program applied software with existing programming language (for example, VC ++, Visual Basic, Delphi, and so forth). This program is much easier to operate and expand by its users. By using a limit switch, users can choose different axes in movement control cards. Also, users can change parts of the parameters in the control software of topper computers to realize different control axes. Combining these 2 methods proves to be convenient for realizing multi-axis control in numerical control systems.

A robust hybrid fuzzy-simulated annealing-intelligent water drops approach for tuning a distribution static compensator nonlinear controller in a distribution system

NASA Astrophysics Data System (ADS)

Bagheri Tolabi, Hajar; Hosseini, Rahil; Shakarami, Mahmoud Reza

2016-06-01

This article presents a novel hybrid optimization approach for a nonlinear controller of a distribution static compensator (DSTATCOM). The DSTATCOM is connected to a distribution system with the distributed generation units. The nonlinear control is based on partial feedback linearization. Two proportional-integral-derivative (PID) controllers regulate the voltage and track the output in this control system. In the conventional scheme, the trial-and-error method is used to determine the PID controller coefficients. This article uses a combination of a fuzzy system, simulated annealing (SA) and intelligent water drops (IWD) algorithms to optimize the parameters of the controllers. The obtained results reveal that the response of the optimized controlled system is effectively improved by finding a high-quality solution. The results confirm that using the tuning method based on the fuzzy-SA-IWD can significantly decrease the settling and rising times, the maximum overshoot and the steady-state error of the voltage step response of the DSTATCOM. The proposed hybrid tuning method for the partial feedback linearizing (PFL) controller achieved better regulation of the direct current voltage for the capacitor within the DSTATCOM. Furthermore, in the event of a fault the proposed controller tuned by the fuzzy-SA-IWD method showed better performance than the conventional controller or the PFL controller without optimization by the fuzzy-SA-IWD method with regard to both fault duration and clearing times.

Power Source Status Estimation and Drive Control Method for Autonomous Decentralized Hybrid Train

NASA Astrophysics Data System (ADS)

Furuya, Takemasa; Ogawa, Kenichi; Yamamoto, Takamitsu; Hasegawa, Hitoshi

A hybrid control system has two main functions: power sharing and equipment protection. In this paper, we discuss the design, construction and testing of a drive control method for an autonomous decentralized hybrid train with 100-kW-class fuel cells (FC) and 36-kWh lithium-ion batteries (Li-Batt). The main objectives of this study are to identify the operation status of the power sources on the basis of the input voltage of the traction inverter and to estimate the maximum traction power control basis of the power-source status. The proposed control method is useful in preventing overload operation of the onboard power sources in an autonomous decentralized hybrid system that has a flexible main circuit configuration and a few control signal lines. Further, with this method, the initial cost of a hybrid system can be reduced and the retrofit design of the hybrid system can be simplified. The effectiveness of the proposed method is experimentally confirmed by using a real-scale hybrid train system.

A Method for Integrating Thrust-Vectoring and Actuated Forebody Strakes with Conventional Aerodynamic Controls on a High-Performance Fighter Airplane

NASA Technical Reports Server (NTRS)

Lallman, Frederick J.; Davidson, John B.; Murphy, Patrick C.

1998-01-01

A method, called pseudo controls, of integrating several airplane controls to achieve cooperative operation is presented. The method eliminates conflicting control motions, minimizes the number of feedback control gains, and reduces the complication of feedback gain schedules. The method is applied to the lateral/directional controls of a modified high-performance airplane. The airplane has a conventional set of aerodynamic controls, an experimental set of thrust-vectoring controls, and an experimental set of actuated forebody strakes. The experimental controls give the airplane additional control power for enhanced stability and maneuvering capabilities while flying over an expanded envelope, especially at high angles of attack. The flight controls are scheduled to generate independent body-axis control moments. These control moments are coordinated to produce stability-axis angular accelerations. Inertial coupling moments are compensated. Thrust-vectoring controls are engaged according to their effectiveness relative to that of the aerodynamic controls. Vane-relief logic removes steady and slowly varying commands from the thrust-vectoring controls to alleviate heating of the thrust turning devices. The actuated forebody strakes are engaged at high angles of attack. This report presents the forward-loop elements of a flight control system that positions the flight controls according to the desired stability-axis accelerations. This report does not include the generation of the required angular acceleration commands by means of pilot controls or the feedback of sensed airplane motions.

Online market research panel members as controls in case-control studies to investigate gastrointestinal disease outbreaks: early experiences and lessons learnt from the UK.

PubMed

Mook, P; McCormick, J; Kanagarajah, S; Adak, G K; Cleary, P; Elson, R; Gobin, M; Hawker, J; Inns, T; Sinclair, C; Trienekens, S C M; Vivancos, R; McCarthy, N D

2018-03-01

Established methods of recruiting population controls for case-control studies to investigate gastrointestinal disease outbreaks can be time consuming, resulting in delays in identifying the source or vehicle of infection. After an initial evaluation of using online market research panel members as controls in a case-control study to investigate a Salmonella outbreak in 2013, this method was applied in four further studies in the UK between 2014 and 2016. We used data from all five studies and interviews with members of each outbreak control team and market research panel provider to review operational issues, evaluate risk of bias in this approach and consider methods to reduce confounding and bias. The investigators of each outbreak reported likely time and cost savings from using market research controls. There were systematic differences between case and control groups in some studies but no evidence that conclusions on the likely source or vehicle of infection were incorrect. Potential selection biases introduced by using this sampling frame and the low response rate are unclear. Methods that might reduce confounding and some bias should be balanced with concerns for overmatching. Further evaluation of this approach using comparisons with traditional methods and population-based exposure survey data is recommended.

Integrated control and health management. Orbit transfer rocket engine technology program

NASA Technical Reports Server (NTRS)

Holzmann, Wilfried A.; Hayden, Warren R.

1988-01-01

To insure controllability of the baseline design for a 7500 pound thrust, 10:1 throttleable, dual expanded cycle, Hydrogen-Oxygen, orbit transfer rocket engine, an Integrated Controls and Health Monitoring concept was developed. This included: (1) Dynamic engine simulations using a TUTSIM derived computer code; (2) analysis of various control methods; (3) Failure Modes Analysis to identify critical sensors; (4) Survey of applicable sensors technology; and, (5) Study of Health Monitoring philosophies. The engine design was found to be controllable over the full throttling range by using 13 valves, including an oxygen turbine bypass valve to control mixture ratio, and a hydrogen turbine bypass valve, used in conjunction with the oxygen bypass to control thrust. Classic feedback control methods are proposed along with specific requirements for valves, sensors, and the controller. Expanding on the control system, a Health Monitoring system is proposed including suggested computing methods and the following recommended sensors: (1) Fiber optic and silicon bearing deflectometers; (2) Capacitive shaft displacement sensors; and (3) Hot spot thermocouple arrays. Further work is needed to refine and verify the dynamic simulations and control algorithms, to advance sensor capabilities, and to develop the Health Monitoring computational methods.

Approximation methods for control of acoustic/structure models with piezoceramic actuators

NASA Technical Reports Server (NTRS)

Banks, H. T.; Fang, W.; Silcox, R. J.; Smith, R. C.

1991-01-01

The active control of acoustic pressure in a 2-D cavity with a flexible boundary (a beam) is considered. Specifically, this control is implemented via piezoceramic patches on the beam which produces pure bending moments. The incorporation of the feedback control in this manner leads to a system with an unbounded input term. Approximation methods in this manner leads to a system with an unbounded input term. Approximation methods in the context of linear quadratic regulator (LQR) state space control formulation are discussed and numerical results demonstrating the effectiveness of this approach in computing feedback controls for noise reduction are presented.

Rotor Position Sensorless Control and Its Parameter Sensitivity of Permanent Magnet Motor Based on Model Reference Adaptive System

NASA Astrophysics Data System (ADS)

Ohara, Masaki; Noguchi, Toshihiko

This paper describes a new method for a rotor position sensorless control of a surface permanent magnet synchronous motor based on a model reference adaptive system (MRAS). This method features the MRAS in a current control loop to estimate a rotor speed and position by using only current sensors. This method as well as almost all the conventional methods incorporates a mathematical model of the motor, which consists of parameters such as winding resistances, inductances, and an induced voltage constant. Hence, the important thing is to investigate how the deviation of these parameters affects the estimated rotor position. First, this paper proposes a structure of the sensorless control applied in the current control loop. Next, it proves the stability of the proposed method when motor parameters deviate from the nominal values, and derives the relationship between the estimated position and the deviation of the parameters in a steady state. Finally, some experimental results are presented to show performance and effectiveness of the proposed method.

Segregation control in vertical Bridgman crystal growth

NASA Astrophysics Data System (ADS)

Tao, Y.; Kou, S.

1996-11-01

To help the crystal grow at a constant dopant concentration in vertical Bridgman crystal growth, the dopant concentration of the growth melt, i.e. the melt from which the crystal grows, was kept constant. To achieve this, three different methods were used to replenish the growth melt at a controlled rate and suppress dopant diffusion between the growth melt and the replenishing melt. In method one, a replenishing crucible having a long melt passageway was immersed in the growth melt. In method two, a replenishing crucible having an independent feed-rate control mechanism was held above the growth melt. In method three, a submerged diffusion baffle was used to form a long melt passageway between the growth melt and the replenishing melt. NaNO 3 was used as a model material for crystal growth. Single crystals were grown by these three methods with effective segregation control. Method two was applied to InSb and single crystals were also grown with effective segregation control.

Integrated Pest Management, Preliminary. Curriculum Guide and Instructional Materials for a Secondary School Vo-Ag Program.

ERIC Educational Resources Information Center

Grady County Board of Education, Cairo, GA.

This curriculum guide presents methods to disseminate information to students interested in dealing with pests, or who have concerns about the environmental impacts of modern pest control methods. Options are encouraged for pest control methods using a combination of natural, biological, cultural, and chemical means of control. Specifically…

Statistical Process Control Charts for Measuring and Monitoring Temporal Consistency of Ratings

ERIC Educational Resources Information Center

Omar, M. Hafidz

2010-01-01

Methods of statistical process control were briefly investigated in the field of educational measurement as early as 1999. However, only the use of a cumulative sum chart was explored. In this article other methods of statistical quality control are introduced and explored. In particular, methods in the form of Shewhart mean and standard deviation…

Barrier methods of birth control - slideshow

MedlinePlus

... ency/presentations/100107.htm Barrier methods of birth control - series—Female normal anatomy To use the sharing ... M. Editorial team. Related MedlinePlus Health Topics Birth Control A.D.A.M., Inc. is accredited by ...

Multiple network interface core apparatus and method

DOEpatents

Underwood, Keith D [Albuquerque, NM; Hemmert, Karl Scott [Albuquerque, NM

2011-04-26

A network interface controller and network interface control method comprising providing a single integrated circuit as a network interface controller and employing a plurality of network interface cores on the single integrated circuit.

Simple method for production of internal control DNA for Mycobacterium tuberculosis polymerase chain reaction assays.

PubMed Central

deWit, D; Wootton, M; Allan, B; Steyn, L

1993-01-01

A simple method for the production of internal control DNA for two well-established Mycobacterium tuberculosis polymerase chain reaction assays is described. The internal controls were produced from Mycobacterium kansasii DNA with the same primers but at a lower annealing temperature than that used in the standard assays. In both assays, therefore, the internal control DNA has the same primer-binding sequences at the target DNA. One-microgram quantities of internal control DNA which was not contaminated with target DNA could easily be produced by this method. The inclusion of the internal control in the reaction mixture did not affect the efficiency of amplification of the target DNA. The method is simple and rapid and should be adaptable to most M. tuberculosis polymerase chain reaction assays. Images PMID:8370752

Integrated control/structure optimization by multilevel decomposition

NASA Technical Reports Server (NTRS)

Zeiler, Thomas A.; Gilbert, Michael G.

1990-01-01

A method for integrated control/structure optimization by multilevel decomposition is presented. It is shown that several previously reported methods were actually partial decompositions wherein only the control was decomposed into a subsystem design. One of these partially decomposed problems was selected as a benchmark example for comparison. The system is fully decomposed into structural and control subsystem designs and an improved design is produced. Theory, implementation, and results for the method are presented and compared with the benchmark example.

A Design Method for a State Feedback Microcomputer Controller of a Wide Bandwidth Analog Plant.

DTIC Science & Technology

1983-12-01

Il IIIz NAVAL POSTGRADUATE SCHOOLMonterey, California THESIS A A DESIGN METHOD FOR A STATE FEEDBACK MICROCOMPUTER CONTROLLER OF A WIDE BANDWIDTH...of a microcomputer regulator, continuous or discrete method can be applied. The o:bjective of this thesis is to provide a continuous controller ...estimation and control type problem. In this thesis , a wide bandwidth analog computer system is chosen as the plant so that the effect of transport

40 CFR Appendix B to Part 425 - Modified Monier-Williams Method

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 31 2012-07-01 2012-07-01 false Modified Monier-Williams Method B... Appendix B to Part 425—Modified Monier-Williams Method Outline of Method Hydrogen sulfide is liberated from.... Quality Control 1. Each laboratory that uses this method is required to operate a formal quality control...

40 CFR Appendix B to Part 425 - Modified Monier-Williams Method

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 30 2011-07-01 2011-07-01 false Modified Monier-Williams Method B... Part 425—Modified Monier-Williams Method Outline of Method Hydrogen sulfide is liberated from an.... Quality Control 1. Each laboratory that uses this method is required to operate a formal quality control...

40 CFR Appendix B to Part 425 - Modified Monier-Williams Method

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Modified Monier-Williams Method B... Part 425—Modified Monier-Williams Method Outline of Method Hydrogen sulfide is liberated from an.... Quality Control 1. Each laboratory that uses this method is required to operate a formal quality control...

Continuous control of chaos based on the stability criterion.

PubMed

Yu, Hong Jie; Liu, Yan Zhu; Peng, Jian Hua

2004-06-01

A method of chaos control based on stability criterion is proposed in the present paper. This method can stabilize chaotic systems onto a desired periodic orbit by a small time-continuous perturbation nonlinear feedback. This method does not require linearization of the system around the stabilized orbit and only an approximate location of the desired periodic orbit is required which can be automatically detected in the control process. The control can be started at any moment by choosing appropriate perturbation restriction condition. It seems that more flexibility and convenience are the main advantages of this method. The discussions on control of attitude motion of a spacecraft, Rössler system, and two coupled Duffing oscillators are given as numerical examples.

Researching on Control Device of Prestressing Wire Reinforcement

NASA Astrophysics Data System (ADS)

Si, Jianhui; Guo, Yangbo; Liu, Maoshe

2017-06-01

This paper mainly introduces a device for controlling prestress and its related research methods, the advantage of this method is that the reinforcement process is easy to operate and control the prestress of wire rope accurately. The relationship between the stress and strain of the steel wire rope is monitored during the experiment, and the one - to - one relationship between the controllable position and the pretightening force of the steel wire rope is confirmed by the 5mm steel wire rope, and the results are analyzed theoretically by the measured elastic modulus. The results show that the method can effectively control the prestressing force, and the result provides a reference method for strengthening the concrete column with prestressed steel strand.

Novel switching method for single-phase NPC three-level inverter with neutral-point voltage control

NASA Astrophysics Data System (ADS)

Lee, June-Seok; Lee, Seung-Joo; Lee, Kyo-Beum

2018-02-01

This paper proposes a novel switching method with the neutral-point voltage control in a single-phase neutral-point-clamped three-level inverter (SP-NPCI) used in photovoltaic systems. A proposed novel switching method for the SP-NPCI improves the efficiency. The main concept is to fix the switching state of one leg. As a result, the switching loss decreases and the total efficiency is improved. In addition, it enables the maximum power-point-tracking operation to be performed by applying the proposed neutral-point voltage control algorithm. This control is implemented by modifying the reference signal. Simulation and experimental results provide verification of the performance of a novel switching method with the neutral-point voltage control.

Computational methods of robust controller design for aerodynamic flutter suppression

NASA Technical Reports Server (NTRS)

Anderson, L. R.

1981-01-01

The development of Riccati iteration, a tool for the design and analysis of linear control systems is examined. First, Riccati iteration is applied to the problem of pole placement and order reduction in two-time scale control systems. Order reduction, yielding a good approximation to the original system, is demonstrated using a 16th order linear model of a turbofan engine. Next, a numerical method for solving the Riccati equation is presented and demonstrated for a set of eighth order random examples. A literature review of robust controller design methods follows which includes a number of methods for reducing the trajectory and performance index sensitivity in linear regulators. Lastly, robust controller design for large parameter variations is discussed.

Temperature control in continuous furnace by structural diagram method

NASA Technical Reports Server (NTRS)

Lei, Xia; Hartley, Tom T.

1991-01-01

The fundamentals of the structural diagram method for distributed parameter systems (DPSs) are presented and reviewed. An example is given to illustrate the application of this method for control design.

Real-Time Adaptive Control of a Magnetic Levitation System with a Large Range of Load Disturbance.

PubMed

Zhang, Zhizhou; Li, Xiaolong

2018-05-11

In an idle light-load or a full-load condition, the change of the load mass of a suspension system is very significant. If the control parameters of conventional control methods remain unchanged, the suspension performance of the control system deteriorates rapidly or even loses stability when the load mass changes in a large range. In this paper, a real-time adaptive control method for a magnetic levitation system with large range of mass changes is proposed. First, the suspension control system model of the maglev train is built up, and the stability of the closed-loop system is analyzed. Then, a fast inner current-loop is used to simplify the design of the suspension control system, and an adaptive control method is put forward to ensure that the system is still in a stable state when the load mass varies in a wide range. Simulations and experiments show that when the load mass of the maglev system varies greatly, the adaptive control method is effective to suspend the system stably with a given displacement.

Real-Time Adaptive Control of a Magnetic Levitation System with a Large Range of Load Disturbance

PubMed Central

Zhang, Zhizhou; Li, Xiaolong

2018-01-01

In an idle light-load or a full-load condition, the change of the load mass of a suspension system is very significant. If the control parameters of conventional control methods remain unchanged, the suspension performance of the control system deteriorates rapidly or even loses stability when the load mass changes in a large range. In this paper, a real-time adaptive control method for a magnetic levitation system with large range of mass changes is proposed. First, the suspension control system model of the maglev train is built up, and the stability of the closed-loop system is analyzed. Then, a fast inner current-loop is used to simplify the design of the suspension control system, and an adaptive control method is put forward to ensure that the system is still in a stable state when the load mass varies in a wide range. Simulations and experiments show that when the load mass of the maglev system varies greatly, the adaptive control method is effective to suspend the system stably with a given displacement. PMID:29751610