bluuebunny/crossref_metadata_2025 huggingface dataset:
Delusion of Pregnancy in Frontotemporal Lobar Degeneration with Motor Neurone Disease (FTLD/MND)
Authors: Larner A. J.
Published: January 2014

Psychotic phenomena such as delusions and hallucinations are rare in frontotemporal dementia syndromes but have recently been recognised as an early feature in some cases of frontotemporal lobar degeneration with motor neurone disease (FTLD/MND). A patient with delusion of pregnancy as an early feature of FTLD/MND is presented to illustrate the need to consider neurodegenerative disease as well as primary psychiatric disorder as the underlying cause of this striking symptom.
Vibration Analysis of Circular Arch Element Using Curvature
Authors: Saffari H. , Tabatabaei R. , Mansouri S.H.
Published: January 2014

In this paper, a finite element technique was used to determine the natural frequencies, and the mode shapes of a circular arch element was based on the curvature, which can fully represent the bending energy and by the equilibrium equations, the shear and axial strain energy were incorporated into the formulation. The treatment of general boundary conditions dose need a consideration when the element is incorporated by the curvature‐based formula. This can be obtained by the introduction of a transformation matrix between nodal curvatures and nodal displacements. The equation of the motion for the element was obtained by the Lagrangian equation. Four examples are presented in order to verify the element formulation and its analytical capability.
The Right Hand Draws the Trees, But the Left Draws the Forest?
Authors: Kleinman Jonathan T. , Gupta Amitabh
Published: January 2014

Spatial processing is lateralized: the right hemisphere is optimized for perceiving global aspects of space (“seeing the forest”), while the left hemisphere specializes in perceiving local aspects of space (“seeing the trees”). However, less is known about how the information is shared across the hemispheres and which areas within the corpus callosum are required for transferring and integrating visuospatial information. Here, we report a 60 year old woman with a mass lesion in the splenium of the corpus callosum who demonstrated visuospatial processing deficits that were out-of-proportion to the rest of her neurological examination. Remarkably, in the Rey-Osterrieth Complex figure task, she copied with her left hand the outlines of the figure (global aspects), whereas with her right hand she drew the details of that figure (local aspects). While hemispheric lesions have demonstrated single dissociations of spatial processing, these results indicate that a lesion in the corpus callosum can produce a double dissociation for high-level spatial tasks, as local and global spatial perception are further dissociated with handedness. Interestingly, as little as the posterior third of the corpus callosum is required for proper visuospatial information transfer and integration, which provides important insight into the interhemispheric functional anatomy that underlies visuospatial perception.
Studying Social Cognition in Patients with Schizophrenia and Patients with Frontotemporal Dementia: Theory of Mind and the Perception of Sarcasm
Authors: Kosmidis Mary H. , Aretouli Eleni , Bozikas Vassilis P. , Giannakou Maria , Ioannidis Panayiotis
Published: January 2014

We investigated social cognition and theory of mind in patients with schizophrenia and in patients with frontotemporal dementia in order to elucidate the cognitive mechanisms involved in the breakdown of these skills in psychiatric and neurological patients. Our tasks included videotaped scenarios of social interactions depicting sincere, sarcastic and paradoxical remarks, as well as lies. We found impaired performance of the schizophrenia group on all theory of mind conditions despite their intact understanding of sincere statements. In contrast, the FTD group performed poorly only when they had to rely on paralinguistic cues indicating sarcasm or lies, and not on paradoxical remarks or sarcasm when given additional verbal cues. Our findings suggest that, while current deficits in social and interpersonal functioning in patients with FTD may reflect a decrement in previously acquired skills, similar deficits in patients with schizophrenia may reflect an altogether inadequately learned process.
Structural Damage Detection Using Energy Flow Models
Authors: Santos E.R.O. , Pereira V.S. , Arruda J.R.F. , Dos Santos J.M.C.
Published: January 2014

The presence of a crack in a structure modifies the energy dissipation pattern. As a consequence, damaged structures can present high localized damping. Experimental tests have revealed that crack nucleation and growth increase structural damping which makes this phenomenon useful as a damage locator. This paper examines the energy flow patterns caused by localized damping in rods, beams and plates using the Energy Finite Element Method (EFEM), the Spectral Element Method (SEM) and the Energy Spectral Element Method (ESEM) in order to detect and locate damage. The analyses are performed at high frequencies, where any localized structural change has a strong influence in the structural response. Simulated results for damage detection in rods, beams, and their couplings calculated by each method and using the element loss factor variation to model the damage, are presented and compared. Results for a simple thin plate calculated with EFEM are also discussed.
A Preliminary Investigation of the Running Digit Span As a Test of Working Memory
Authors: Jahanshahi Marjan , Saleem T. , Ho Aileen K. , Fuller R. , Dirnberger Georg
Published: January 2014

The objective of this study was to compare performance on different versions of the running span task, and to examine the relationship between task performance and tests of episodic memory and executive function. We found that the average capacity of the running span was approximately 4 digits, and at long sequence lengths, performance was no longer affected by varying the running span window. Both episodic and executive function measures correlated with short and long running spans, suggesting that a simple dissociation between immediate memory and executive processes in short and long running digit span tasks may not be warranted.
A Novel Low‐Torque Ball Re‐Positioning Scheme Based on a Sliding‐Mode Ball Observer for an Automatic Balancer System
Authors: Chao Paul C.-P. , Chiu Chi-Wei , Shih Kai-Teng
Published: January 2014

A novel low‐torque ball re‐positioning scheme based on a sliding‐mode ball observer is developed in this study with the aim to precisely reside the rolling ball inside an automatic balancer system (ABS) to its desired position – 180 degree opposite to the inherent imbalance of the rotating system which the ABS is attached to. In this way, the ABS is capable of substantially reducing radial vibrations of the rotating system for a decent balancing. For preliminary feasibility, the case of a single ball is considered in this study. The first step is to establish the dynamic model of the system, which is followed by the analysis to ensure stability of the desired ball position. The second step is to forge a sliding‐mode observer for estimating on‐line position and velocity of the ball. With ball estimation capability, a low‐torque speed regulator that essentially generates a series of speed drops to the neighborhood of suspension resonance is proposed to overcome practical ball rolling friction for residing the ball at the desired position. The design characteristic of low‐torque required for the regulator is particularly suited to most of commercial spindle motors which can only output limited torques at high speeds. Finally, simulations and experiments are conducted for a benchmark problem of optical disc drives in order to verify the effectiveness of the proposed scheme of the sliding‐mode observer and the low‐torque speed regulator.
A New Fault Diagnosis Method of Rotating Machinery
Authors: Chen Chih-Hao , Shyu Rong-Juin , Ma Chih-Kao
Published: January 2014

This paper presents a new fault diagnosis procedure for rotating machinery using the wavelet packets‐fractal technology and a radial basis function neural network. The faults of rotating machinery considered in this study include imbalance, misalignment, looseness and imbalance combined with misalignment conditions. When such faults occur, they usually induce non‐stationary vibrations to the machine. After measuring the vibration signals, the wavelet packets transform is applied to these signals. The fractal dimension of each frequency bands is extracted and the box counting dimension is used to depict the failure characteristics of the vibration signals. The failure modes are then classified by a radial basis function neural network. An experimental study was performed to evaluate the proposed method and the results show that the method can effectively detect and recognize different kinds of faults of rotating machinery.
Dissociative Disturbance in Hangul-Hanja Reading after a Left Posterior Occipital Lesion
Authors: Park Key-Chung , Yoon Sung-Sang
Published: January 2014

Since the Korean language has two distinct writing systems, phonogram (Hangul) and ideogram (Hanja: Chinese characters), alexia can present with dissociative disturbances in reading between the two systems. A 74-year-old right-handed man presented with a prominent reading impairment in Hangul with agraphia of both Hangul and Hanja after a left posterior occipital- parietal lesion. He could not recognize single syllable words and nonwords in Hangul, and visual errors were predominant in both Hanja reading and the Korean Boston Naming Test. In addition, he had difficulties in visuoperceptual tests including Judgment of Line Orientation, Hierarchical Navon figures, and complex picture scanning. These findings are consistent with the hypothesis that Hangul reading impairment results from a general visual perceptual deficit. However, this assumption cannot explain why performance on visually complex Hanja was better than performance on visually simple Hanja in our patient. In addition, the patient did not demonstrate higher accuracy on Hanja characters with fewer strokes than on words with more strokes. Thus, we speculate that the left posterior occipital area may be specialized for Hangul letter identification in this patient. This case demonstrates that Hangul-Hanja reading dissociation impairment can occur after occipital-parietal lesions.
Superelement Verification in Complex Structural Models
Authors: Dupont B. , Pillet E. , Cogan S.
Published: January 2014

The objective of this article is to propose decision indicators to guide the analyst in the optimal definition of an ensemble of superelements in a complex structural assembly. These indicators are constructed based on comparisons between the unreduced physical model and the approximate solution provided by a nominally reduced superelement model. First, the low contribution substructure slave modes are filtered. Then, the minimum dynamical residual expansion is used to localize the superelements which are the most responsible for the response prediction errors. Moreover, it is shown that static residual vectors, which are a natural result of these calculations, can be included to represent the contribution of important truncated slave modes and consequently correct the deficient superelements. The proposed methodology is illustrated on a subassembly of an aeroengine model.
Associative Visual Agnosia: A Case Study
Authors: Charnallet A. , Carbonnel S. , David D. , Moreaud O.
Published: January 2014

We report a case of massive associative visual agnosia. In the light of current theories of identification and semantic knowledge organization, a deficit involving both levels of structural description system and visual semantics must be assumed to explain the case. We suggest, in line with a previous case study [1], an alternative account in the framework of (non abstractive) episodic models of memory [4].
Undifferentiation of Somatic Responses to Emotions in a Case of Functional Amnesia
Authors: Tramoni E. , Khalfa S. , Felician O. , Fonseca A. Trebuchon-Da , Poncet M. , Ceccaldi M.
Published: January 2014

The term functional amnesia (FA) has been proposed for cases of memory impairment presenting with severe retrograde amnesia in the absence of cerebral injury or history of psychiatric disturbance. Emotional flattening has often been reported alongside FA, however the mechanism of such a modification is unknown. This study aimed to explore the emotional processing in a rare case of a patient with FA complaining of severe emotional flattening.

We presented ecological dynamic video stimuli conveying strong peaceful and fearful emotions to the patient and 13 controls. We
then explored their emotional responses considering both conscious emotional judgements and automatic psychophysiological
responses (skin conductance) and facial muscular activity (corrugator supercilii). Both patient P.P. and controls perfectly
recognized the emotions conveyed by the films. However, P.P. failed to showan increased skin conductance and corrugator activity
as found in controls during fearful film extracts compared with peaceful extracts. Taken together, these finding demonstrate the
presence of an emotional deficit, characterized by a failure to generate appropriate somatic responses to positive and negative
stimuli. Although this altered somatic processing did not interfere with PP’s explicit recognition of emotion, it modified his
emotional experience, thereby constituting a possible explanation for his emotional flattening. This study therefore suggests that
FA is not limited to a mnemonic impairment, but is a more complex disorder, involving also the processing of emotionally loaded
experiences.
Identification of a Non‐Linear Landing Gear Model Using Nature‐Inspired Optimization
Authors: Viana Felipe A.C. , Steffen Valder , Zanini Marcelo A.X. , Magalhães Sandro A. , Góes Luiz C.S.
Published: January 2014

This work deals with the application of a nature‐inspired optimization technique to solve an inverse problem represented by the identification of an aircraft landing gear model. The model is described in terms of the landing gear geometry, internal volumes and areas, shock absorber travel, tire type, and gas and oil characteristics of the shock absorber. The solution to this inverse problem can be obtained by using classical gradient‐based optimization methods. However, this is a difficult task due to the existence of local minima in the design space and the requirement of an initial guess. These aspects have motivated the authors to explore a nature‐inspired approach using a method known as LifeCycle Model. In the present formulation two nature‐based methods, namely the Genetic Algorithms and the Particle Swarm Optimization were used. An optimization problem is formulated in which the objective function represents the difference between the measured characteristics of the system and its model counterpart. The polytropic coefficient of the gas and the damping parameter of the shock absorber are assumed as being unknown: they are considered as design variables. As an illustration, experimental drop test data, obtained under zero horizontal speed, were used in the non‐linear landing gear model updating of a small aircraft.
Evaluation of the Performance of Three Different Methods Used in the Identification of Rigid Body Properties
Authors: Almeida R.A.B. , Urgueira A.P.V. , Maia N.M.M.
Published: January 2014

The identification of the rigid body properties of a structure is an important matter in various structural dynamic applications, namely in structural modification (coupling/uncoupling), optimization and vibration control. In most situations, the experimental route is the only via to obtain the desired dynamic properties. This goal is achieved by an inverse process which starts from the measurement of Frequency Response Functions (FRFs) and ends on matrices describing the mass distribution of a rigid body.

The objective of the present article is the evaluation and comparison of the performance of three different kinds of identification methods that share a common characteristic – they all use FRFs as inputs to the inverse process. One of them, the Inertia Restraint Method (IRM) makes use of the accelerance FRF (information condensed at zero frequency), while the other two methods make use of receptance FRFs as inputs, although in different manners; in one of them the properties are evaluated directly from the measurement data – Direct Physical Parameter Identification Method (DPPIM) – whereas the other type requires a modal identification procedure as an intermediate step – Modal Method (MM). An actual experimental structure forms the case study to illustrate the performance of the three different techniques.
Horizontal Bulk Material Pressure in Silo Subjected to Impulsive Load
Authors: Tatko Radosław , Kobielak Sylwester
Published: January 2014

This paper describes laboratory tests carried out in the steel flat‐bottomed silo model filled with sand, subjected to external dynamic loads. The model was placed on a system of springs, which represent subsoil. The loads in the form of horizontal impulses were applied to the bottom plate of the silo. Horizontal pressure‐time courses were used to analyze the influence of subsoil vibrations on the distribution changes of these pressures. Basic conclusion: (1) the subsoil vibrations cause two types of changes of the horizontal pressures: stable changes which are observed when the model vibrations finish and cyclic of short duration (brief) changes; (2) the subsoil vibrations either generate stable increase or stable decrease of the pressures from before vibrations or do not generate any essential stable change; (3) the cyclic dynamic changes of the horizontal pressures depend on the direction of the silo wall displacements and they are the function of the values of these displacements.
Real Time Estimation of Modal Parameters and Their Quality Assessment
Authors: Uhl Tadeusz , Petko Maciej , Karpiel Grzegorz , Klepka Andrzej
Published: January 2014

In this paper the recursive method for modal parameters estimation is formulated and verified. Formulated algorithms are implemented in the FPGA electronic chip. As a result, the modal parameters and confidence bounds for the modal parameters are obtained in real time. The algorithms and their implementations are tested on laboratory test rig data and applied to – flight modal analysis of an airframe structure.
Finite‐Element Formulae for Calculating the Sectional Forces of a Bernoulli‐Euler Beam on Continuously Viscoelastic Foundation Subjected to Concentrated Moving Loads
Authors: Lou Ping
Published: January 2014

In the finite element method, there are shortcomings using the conventional formulae to calculate the sectional forces, i.e., the bending moment and the shear force, at any cross‐section of Bernoulli‐Euler beam under dynamic loads. This paper presents some new finite‐element formulae overcoming the shortcomings of the conventional ones to calculate the sectional forces at any cross‐section of a Bernoulli‐Euler beam on continuously viscoelastic foundation subjected to concentrated moving loads. The proposed formulae can easily degenerate into the formulae for calculating the sectional forces of a simply supported or a continuous Bernoulli‐Euler beam subjected to concentrated moving loads, and into the formulae for calculating the sectional forces of a Bernoulli‐Euler beam on Winkler foundation under static loads. Five numerical examples including static and dynamic analyses are chosen to illustrate the application of the proposed formulae. Numerical results show: (1) compared with the conventional formulae, the proposed formulae can improve the calculation accuracy of the sectional forces of beam; (2) one should use the proposed formulae, not the conventional formulae, to calculate the sectional forces at any cross‐section in Bernoulli‐Euler beam.
Dopaminergic Modulation of Prospective Memory in Parkinson’s Disease
Authors: Costa Alberto , Peppe Antonella , Brusa Livia , Caltagirone Carlo , Gatto Ilaria , Carlesimo Giovanni Augusto
Published: January 2014

Growing interest is present in literature on the study of prospective memory functioning in Parkinson’s disease (PD). Current data indicate that prospective memory may be impaired in PD and a relationship with general executive dysfunctioning has been suggested. However, although the dopamine dependency of cognitive dysfunction in PD has been widely investigated, poor is known on the dopaminergic modulation of PM. In the present study we explored the effect of acute administration of levodopa on the performance of a PD sample (n = 20) in a time‐based prospective memory task. PD patients were evaluated in the morning after a 12‐hour therapy wash‐out in two experimental conditions: i) after levodopa assumption (“on”); (ii) without drug administration (“off”). The experimental task required to execute three uncorrelated actions after 10′ for three consecutive trials. Distinct scores for the spontaneous recall of the intention to perform the actions (prospective component) and for the correct execution of the actions (retrospective component) have been computed. Results showed that in the “off”condition PD patients were selectively impaired on the prospective component of the task. However, L‐dopa administration significantly improved PD patients’ performance actually restoring the prospective memory deficit. These results support a critical role of dopaminergic modulation in prospective memory processes in PD patients, possibly through the replacement of dopamine levels in fronto‐striatal pathways.
Chaotic Vibrations of Closed Cylindrical Shells in a Temperature Field
Authors: Krysko A.V. , Awrejcewicz J. , Kuznetsova E.S. , Krysko V.A.
Published: January 2014

Complex vibrations of cylindrical shells embedded in a temperature field are studied, and the Bubnov‐Galerkin method in higher approximations and in the Fourier representation is applied. Both lack and influence of temperature field on the shell dynamics are analyzed.
Measurement of FRFs and Modal Identification in Case of Correlated Multi‐Point Excitation
Authors: Fuellekrug U. , Boeswald M. , Goege D. , Govers Y.
Published: January 2014

The modal identification of large and dynamically complex structures often requires a multi‐point excitation. Sine sweep excitation runs are applied when it is necessary to concentrate more energy on each line of the frequency spectrum. The conventional estimation of FRFs from multi‐point excitation requires uncorrelated excitation signals. In case of multi‐point (correlated) sine sweep excitation, several sweep runs with altered excitation force patterns have to be performed to estimate the FRFs. An alternative way, which offers several advantages, is to process each sine sweep run separately. The paper first describes the conventional method for FRF estimation in case of multi‐point excitation, followed by two alternative methods applicable in case of correlated excitation signals. Both methods generate a virtual single‐point excitation from a single run with multi‐point excitation. In the first method, an arbitrary structural point is defined as a virtual driving point. This approach requires a correction of the modal masses obtained from modal analysis. The second method utilizes the equality of complex power to generate virtual FRFs along with a single virtual driving point. The computation of FRFs and the modal identification using virtual single‐point excitation are explained. It is shown that the correct set of modal parameters can be identified. The application of the methods is elucidated by an illustrative analytical example. It could be shown that the separate evaluation of symmetric and anti‐symmetric multi‐point excitation runs yield obviously better and more reliable results compared to the conventional method. In addition, the modal analysis of the separate symmetric and anti‐symmetric excitation runs is easier, since the stabilization diagrams are easier to interpret. The described methods were successfully applied during the Ground Vibration Tests on Airbus A380 and delivered excellent results. The methods are highly advantageous and may thus be established as a new standard procedure for testing aerospace structures.
Public Events and Flashbulb Memories in Parkinson’s Disease
Authors: Borg Céline , Antérion Catherine Thomas , Vioux Hélène , Poujois Aurélia , Laurent Bernard
Published: January 2014

Public events and Flashbulb memories were investigated in 12 non‐demented patients with Parkinson’s disease (PD) and 12 controls. Knowledge of public events and flashbulbs memories were assessed using a Famous Events Test (EVE 30). Contributions of semantic, episodic, as well as executive functioning and anterograde memory were examined. Results primarily showed that the performances of patients with PD were lower than these of controls in 4 tasks: free recall, specific questions, dating events and date recognition. They also had difficulties in finding the temporal order of 8 events. In contrast, the PD group benefited from events recognition themselves to the same extent as the controls. Secondly, the recall of flashbulb memories (FBM) was lower in the PD group than in the controls. Finally, correlations appeared in PD between the detailed recall of the events with the “recall” abilities of the MATTIS scale, possibly reflect an impairment in rebuilding memories. A positive correlation is also observed with the initiation score of the MATTIS (executive component), suggesting that the difficulties of rebuilding can be related to a dysfunction in accessing information because of a certain degree of frontal amnesia.
Pressure Hull Analysis under Shock Loading
Authors: Lee Ya-Jung , Hsu Chia-Hao , Huang Chien-Hua
Published: January 2014

The hull of high performance submarines must resist underwater shock loading due to exploding torpedoes or depth bombs. An underwater shock involving an initial shock wave and successive bubble pulsating waves is so complex that a theoretical technique for deriving shock pressure distribution is required for improving simulation efficiency. Complete shock loading is obtained theoretically in this work, and responses of a submarine pressure hull are calculated using ABAQUS USA (Underwater Shock Analysis) codes. In the long run, this deflection and stress data will assist in examining the structural arrangement of the submarine pressure hull.
Agraphia for Kanji Resulting From a Left Posterior Middle Temporal Gyrus Lesion
Authors: Sakurai Yasuhisa , Mimura Imari , Mannen Toru
Published: January 2014

Objective: To clarify whether agraphia or alexia occurs in lesions of the left posterior middle temporal gyrus.

Methods: We assessed the reading and writing abilities of two patients with this lesion using kanji (Japanese morphograms) and
kana (Japanese syllabograms).

Results: Patient 1 first presented with pure alexia more impaired for kana after an infarction in the left middle and inferior occipital
gyri and right basal occipital cortex, and after a second infarction in the left posterior middle temporal gyrus adjoining the first
lesion he showed alexia with agraphia for kanji and worsened alexia for kana; kanji alexia recovered over the following six to 10
months. Patient 2 presented with alexia with agraphia for kanji following a hemorrhage in the left posterior middle and inferior
temporal gyri, which resolved to agraphia for kanji at two months after onset. Kana nonword reading was also slightly impaired,
but became normal by six months post‐onset. In both patients, kanji agraphia was mostly due to impaired character recall.

Conclusion: The present patients demonstrate that damage to the left posterior middle temporal gyrus alone can cause agraphia
for kanji. If the adjacent mid fusiform/inferior temporal gyri (Area 37) are spared, the kanji alexia is transient.
Autonoetic Consciousness in Autobiographical Memories after Medial Temporal Lobe Resection
Authors: Noulhiane M. , Piolino P. , Hasboun D. , Clemenceau S. , Baulac M. , Samson S.
Published: January 2014

This study aims to investigate autonoetic consciousness associated with episodic autobiographical memory in patients who had undergone unilateral medial temporal lobe resection for intractable epilepsy. Autonoetic consciousness, defined as the conscious feeling of mentally travelling back in time to relive a specific event, was assessed using the Remember/Know (R/K) paradigm across different time periods as proposed in the autobiographical memory task developed by Piolino et al. (TEMPau task). Results revealed that the two patient groups (left and right temporal resection) gave reduced sense of reliving (R) responses and more familiarity (K) responses than healthy controls. This poor autonoetic consciousness was highlighted when patients were asked to justify their Remember responses by recalling sensory‐perceptive, affective or spatiotemporal specific details across all life periods. These results support the bilateral MTL contribution to episodic autobiographical memory covering the entire lifespan, which is consistent with the multiple trace theory of MTL function [7,9]. This study also demonstrates the bilateral involvement of MTL structures in recalling specific details of personal events characterized by autonoetic consciousness.
Effect of Distorted Visual Feedback on the Sense of Agency
Authors: Farrer C. , Bouchereau M. , Jeannerod M. , Franck N.
Published: January 2014

It has been hypothesized that an internal model is involved in controlling and recognizing one’s own actions (action attribution). This results from a comparison process between the predicted sensory feedback of the action and its real sensory consequences. The aim of the present study is to distinguish the respective importance of two action parameters (time and direction) on such an attribution judgment.

We used a device that allows introduction of discordance between the movements actually performed and the sensory feedback
displayed on a computer screen. Participants were asked to judge whether they were viewing (1) their own movements, (2) their
own movements modified (spatially or temporally displaced), or (3) those of another agent (i.e, the experimenter). In fact, in all
conditions they were only shown their own movements either unaltered or modified by varying amounts in space or time.

Movements were only attributed to another agent when therewas a high spatial discordance between participants’ hand movements
and sensory feedback. This study is the first to show that the direction of movements is a cardinal feature in action attribution,
whereas temporal properties of movements play a less important role.
Far‐Field Power Transmissions in Orthotropic Plates: A New Approach
Authors: Mandal Nirmal K.
Published: January 2014

The structural intensity (SI) technique is an essential tool for locating and ranking vibration sources and sinks on structures. It can quantify vibration fields by plotting a vector map of energy transmission on the structures. In this paper, a different strategy, changing coordinate systems of plate equations, is used to develop an intensity equation from shear force components in both x and y directions. The formulation is carried out in the frequency domain considering flexural waves. Orthotropic plate theory, far‐field conditions, Fourier transform, and finite difference approximation are considered. The same intensity definition is obtained using this different strategy. A dual‐channel FFT analyser is essential for data acquisition to get an intensity vector in a particular direction for far‐field conditions.
The Factors that Induce or Overcome Freezing of Gait in Parkinson’s Disease
Authors: Rahman S. , Griffin H. J. , Quinn N. P. , Jahanshahi M.
Published: January 2014

Freezing of gait (FoG), a transient halt in walking, is a major mobility problem for patients with Parkinson’s disease (PD). This study examined the factors that induce FoG, and identified the cues and strategies that help overcome it through a postal survey of 130 PD patients. 72% reported FoG. The factors that commonly induced FoG were turning, fatigue, confined spaces and stressful situations, in addition to emotional factors. FoG was also ameliorated by various attentional and external cueing strategies. The concept of paradoxical kinesis, the potential neural substrates of such external cueing effects, and their importance for rehabilitation in PD are discussed.
Structural Damping with Friction Beams
Authors: Gaul L. , Roseira J. , Becker J.
Published: January 2014

In the last several years, there has been increasing interest in the use of friction joints for enhancing damping in structures. The joints themselves are responsible for the major part of the energy dissipation in assembled structures. The dissipated work in a joint depends on both the applied normal force and the excitation force. For the case of a constant amplitude excitation force, there is an optimal normal force which maximizes the damping. A ‘passive’ approach would be employed in this instance. In most cases however, the excitation force, as well as the interface parameters such as the friction coefficient, normal pressure distribution, etc., are not constant. In these cases, a ‘semi‐active’ approach, which implements an active varying normal force, is necessary. For the ‘passive’ and ‘semi‐active’ approaches, the normal force has to be measured. Interestingly, since the normal force in a friction joint influences the local stiffness, the natural frequencies of the assembled structure can be tuned by adjusting the normal force. Experiments and simulations are performed for a simple laboratory structure consisting of two superposed beams with friction in the interface. Numerical simulation of the friction interface requires non‐linear models. The response of the double beam system is simulated using a numerical algorithm programmed in MATLAB which models point‐to‐point friction with the Masing friction model. Numerical predictions and measurements of the double beam free vibration response are compared. A practical application is then described, in which a friction beam is used to damp the vibrations of the work piece table on a milling machine. The increased damping of the table reduces vibration amplitudes, which in turn results in enhanced surface quality of the machined parts, reduction in machine tool wear, and potentially higher feed rates. Optimal positioning of the friction beams is based on knowledge of the mode shapes, which are obtained from experimental modal analysis. The modal damping and the natural frequencies for the two dominant modes are measured for several combinations of excitation force and normal force.
Vibration Measurement of Rotating Blades Using a Root Embedded PZT Sensor
Authors: Sunar M. , Al-Bedoor B.O.
Published: January 2014

Finite element and experimental studies are carried out to test the suitability of a piezoelectric (PZT) sensor in measuring vibrations of blades modeled as beams. The rotating system contains twelve blades mounted to the shaft through a rotor. The PZT sensor is secured in the root between the rotor and blade. First, finite element results are obtained using the finite element package ANSYS. A modal analysis is performed on the system to identify modes and mode shapes. Transient, harmonic and steady‐state responses are then computed to test the ability of the PZT sensor in generating signals for blade vibrations. For the experimental part, the blade vibration signals are produced using the PZT sensor and a strain‐gage, and the outputs are compared with each other. From both the finite element and experimental results, it is concluded that the root‐embedded PZT sensor can be effectively used for blade vibration measurements in a wide range of cases.
Foreign Accent Syndrome Mimicked by Garcin Syndrome with Spontaneous Resolution
Authors: Hoffmann Michael
Published: January 2014

An English speaking women developed a French accent, without any aphasic syndromes, in conjunction with multiple left sided cranial nerve deficits, temporally related to cranial trauma. Extensive testing with multimodality magnetic resonance imaging, cerebrospinal fluid and laboratory analysis was unremarkable. She was followed over a 3 year period during which her French accent resolved as did the majority of her multiple unilateral cranial neuropathies. The neurological diagnoses included a foreign accent syndrome attributed to a reversible Garcin syndrome.
Optical Fibres Contactless Sensor for Dynamic Testing of Lightweight Structures
Authors: Bregant L. , Bressanutti M.
Published: January 2014

With dynamic testing, engineers describe activities focused on the identification of some properties of vibrating structures. This step requires for the measurements of excitations and responses signals, applying appropriate sensors directly on the test article. These instruments modify the system′s mass and stiffness distributions and eventually the eigen‐properties of the structure. These errors become unacceptable especially when testing lightweight structures. This paper shows the results of some tests performed on a small compressor with the purpose of identifying the blades’ natural frequencies and modes. It compares the acquisitions performed with standard accelerometers and two different contact‐less systems using as exciters either a micro‐hammer or a micro inertial shaker. The paper shows how the contact‐less sensors provide good quality data and consistent results in the mode identification phase.
Design of a 20,000 Pound Variable Stiffness Actuator for Structural Vibration Attenuation
Authors: Leavitt John , Bobrow James E. , Jabbari Faryar
Published: January 2014

This paper describes the design of a novel actuator capable of protecting a full scale structure from severe load conditions. The design includes a cylinder filled with pressurized nitrogen and uses commercially available components. We demonstrate that the actuator behaves like a spring with an adjustable unstretched length, and that the effective spring stiffness can be changed easily by changing the initial cylinder pressure. In order to test the actuator on a full scale structure, an effective spring constant of approximately 10,000 pounds/inch was required over a two inch stroke. Because of the spring‐like behavior, rather than damper‐like behavior, the actuator does not transmit high forces to a vibrating structure like linear viscous dampers do when velocities are high. We analyze features of critical importance to the design of the actuator such as the cylinder dimensions, operating pressure, and valve selection. We then investigate the performance using a novel experimental apparatus that mimics the dynamics of a single story building, but has 1/400 the weight.
Simple Models for the Dynamic Modeling of Rotating Tires
Authors: Delamotte J.C. , Nascimento R.F. , Arruda J.R.F.
Published: January 2014

Large Finite Element (FE) models of tires are currently used to predict low frequency behavior and to obtain dynamic model coefficients used in multi‐body models for riding and comfort. However, to predict higher frequency behavior, which may explain irregular wear, critical rotating speeds and noise radiation, FE models are not practical. Detailed FE models are not adequate for optimization and uncertainty predictions either, as in such applications the dynamic solution must be computed a number of times. Therefore, there is a need for simpler models that can capture the physics of the tire and be used to compute the dynamic response with a low computational cost. In this paper, the spectral (or continuous) element approach is used to derive such a model. A circular beam spectral element that takes into account the string effect is derived, and a method to simulate the response to a rotating force is implemented in the frequency domain. The behavior of a circular ring under different internal pressures is investigated using modal and frequency/wavenumber representations. Experimental results obtained with a real untreaded truck tire are presented and qualitatively compared with the simple model predictions with good agreement. No attempt is made to obtain equivalent parameters for the simple model from the real tire results. On the other hand, the simple model fails to represent the correct variation of the quotient of the natural frequency by the number of circumferential wavelengths with the mode count. Nevertheless, some important features of the real tire dynamic behavior, such as the generation of standing waves and part of the frequency/wavenumber behavior, can be investigated using the proposed simplified model.
Effects on Cognition of Stereotactic Lesional Surgery For the Treatment of Tremor in Multiple Sclerosis
Authors: Jahanshahi Marjan , Pieter Socorro , Alusi Sundus H. , Jones Catherine R. G. , Glickman Scott , Stein John , Aziz Tipu , Bain Peter G.
Published: January 2014

Objective:To assess the effect of stereotactic lesional surgery for treatment of tremor in multiple sclerosis on cognition.

Methods:Eleven patients (3 males, 8 females) with multiple sclerosis participated in the study. Six subjects comprised the surgical group and five the matched control group. All patients were assessed at baseline and three months using a neuropsychological test battery that included measures of intellectual ability, memory, language, perception and executive function.

Results:There were no significant differences between the surgical and control groups and no change from pre to post testing except for a decline in scores on the Mini-Mental State Examination (MMSE), WAIS-R Digit Span and Verbal Fluency in the surgical group.

Conclusions:The results indicate that stereotactic lesional surgery does not result in major cognitive impairment in multiple sclerosis. However, the decline in MMSE scores, digit span and verbal fluency require further investigation in a larger sample.
Two Routes to Losing One’s Past Life: A Brain Trauma, an Emotional Trauma
Authors: Ouellet Julie , Rouleau Isabelle , Labrecque Raymonde , Bernier Gilles , Scherzer Peter B.
Published: January 2014

Organic and psychogenic retrograde amnesia have long been considered as distinct entities and as such, studied separately. However, patterns of neuropsychological impairments in organic and psychogenic amnesia can bear interesting resemblances despite different aetiologies. In this paper, two cases with profound, selective and permanent retrograde amnesia are presented, one of an apparent organic origin and the other with an apparent psychogenic cause. The first case, DD, lost his memory after focal brain injury from a nail gun to the right temporal lobe. The second case, AC, lost her memory in the context of intense psychological suffering. In both cases, pre-morbid autobiographical memory for people, places and events was lost, and no feeling of familiarity was experienced during relearning. In addition, they both lost some semantic knowledge acquired prior to the onset of the amnesia. This contrasts with the preservation of complex motor skills without any awareness of having learned them. Both DD and AC showed mild deficits on memory tests but neither presented any anterograde amnesia. The paradox of these cases–opposite causes yet similar clinical profile–exemplifies the hypothesis that organic and psychogenic amnesia may be two expressions of the same faulty mechanism in the neural circuitry.
Evidence for Individual Face Discrimination in Non‐Face Selective Areas of the Visual Cortex in Acquired Prosopagnosia
Authors: Dricot Laurence , Sorger Bettina , Schiltz Christine , Goebel Rainer , Rossion Bruno
Published: January 2014

Two areas in the human occipito‐temporal cortex respond preferentially to faces: ‘the fusiform face area’ (‘FFA’) and the ‘occipital face area’ (‘OFA’). However, it is unclear whether these areas have an exclusive role in processing faces, or if sub‐maximal responses in other visual areas such as the lateral occipital complex (LOC) are also involved. To clarify this issue, we tested a brain‐damaged patient (PS) presenting a face‐selective impairment with functional magnetic resonance imaging (fMRI). The right hemisphere lesion of the prosoagnosic patient encompasses the ‘OFA’ but preserves the ‘FFA’ and LOC [14,16]. Using fMRI‐adaptation, we found a larger response to different faces than repeated faces in the ventral part of the LOC both for normals and the patient, next to her right hemisphere lesion. This observation indicates that following prosopagnosia, areas that do not respond preferentially to faces such as the ventral part of the LOC (vLOC) may still be recruited to subtend residual perception of individual faces.
Visual Scanning and Reading Ability in Normal and Dyslexic Children
Authors: Ferretti G. , Mazzotti S. , Brizzolara D.
Published: January 2014

Very few studies have investigated the development of visual search of aligned stimuli in relation to normal reading acquisition and in developmental dyslexia.

In this study we used a new computerised experimental task which requires a visuo‐motor response (RT) to a target appearing unpredictably in one out of seven different spatial positions on a horizontally aligned array of 18 geometrical figures.

The aims of the study were to investigate: (1) the visual scanning development in normal children from pre‐school to school age; (2) whether visual scanning performance in kindergarten children could predict reading acquisition; (3) the visual scanning abilities in a group of developmental dyslexic children.

The main results were: (1) a significant decrement of RTs with age and a progressive increase of the left‐to‐right gradient with
reading experience; (2) visual scanning abilities in kindergarten proved to be a good predictor of reading acquisition; (3) dyslexics were slow scanners and did not present the left‐to‐right strategy typical of normal readers.

The results support the hypothesis of a relationship between visual scanning and reading abilities.
Continuous Modeling of a Multi‐Link Flexible Transmission
Authors: Peled Irit , Halevi Yoram
Published: January 2014

The problem of dynamic, infinite dimension, modeling of a transmission is considered. An accurate Laplace transfer function matrix of the system that consists of flexible shafts connected by gears that are either rigid or flexible is found. The first step is deriving a set of single input, infinite dimension, transfer functions for a single uniform link. The building blocks of those transfer functions are time delays, representing the wave motion, and low order rational expressions, representing the boundary phenomena. The next step is combining these individual transfer functions into an overall model of the transmission, by means of the link reaction approach that makes use of the geometric relationships and reaction moments between neighboring links. The outcome is a generalized dynamic model with the moments in the gear pairs as the generalized state vector. The explicit and highly structured form of the transfer functions allows physical insight into the system, exact calculation of natural frequencies and the construction of exact simulation schemes built from standard blocks that are available in multi‐purpose simulation software.
Recognition Memory and Prefrontal Cortex: Dissociating Recollection and Familiarity Processes Using rTMS
Authors: Turriziani Patrizia , Oliveri Massimiliano , Salerno Silvia , Costanzo Floriana , Koch Giacomo , Caltagirone Carlo , Carlesimo Giovanni Augusto
Published: January 2014

Recognition memory can be supported by both the assessment of the familiarity of an item and by the recollection of the context in which an item was encountered. The neural substrates of these memory processes are controversial. To address these issues we applied repetitive transcranial magnetic stimulation (rTMS) over the right and left dorsolateral prefrontal cortex (DLPFC) of healthy subjects performing a remember/know task. rTMS disrupted familiarity judgments when applied before encoding of stimuli over both right and left DLPFC. rTMS disrupted recollection when applied before encoding of stimuli over the right DLPFC. These findings suggest that the DLPFC plays a critical role in recognition memory based on familiarity as well as recollection.