bluuebunny/crossref_metadata_2025 huggingface dataset:
The functional neuroanatomy of schizophrenic subsyndromes
Authors: HONEY G. D. , SHARMA T. , SUCKLING J. , GIAMPIETRO V. , SONI W. , WILLIAMS S. C. R. , BULLMORE E. T.
Published: July 2004

Background. There is considerable variability between patients in their expression of the diverse range of symptoms encompassed by the syndrome of schizophrenia, which may modulate functional activation to cognitive processing.

Method. Here we investigate associations between schizophrenic subsyndrome scores, identified by factor analysis, and experimentally controlled brain activation. Five factors were defined by rotated principal components analysis of PANSS rating scale measurements in 100 patients with schizophrenia. A subsample of 30 patients and a group of 27 comparison subjects were studied using functional magnetic resonance imaging (fMRI) during the performance of two periodically designed cognitive activation experiments: verbal working memory and psychomotor sequencing.

Results. Factor analysis replicated the five dimensions consistently reported. Within the patient group, power of activation by working memory was negatively associated with global symptom severity in left lingual and temporo-parietal cortices; negatively associated with positive subsyndrome scores in left inferior frontal and superior temporal cortices and basal ganglia; and positively associated with negative subsyndrome scores in lateral and medial premotor cortex. No relationship was observed between subsyndrome scores and functional activation during the motor task. Between-group comparisons demonstrated reduced power of response to the working memory task by patients in bilateral dorsolateral prefrontal and left pre- and post-central cortices.

Conclusions. In this study we observed task-specific modulation of functional response associated with symptom expression in schizophrenia. Our findings are compatible with previous empirical findings and theoretical conceptualization of human brain function, in terms of capacity constraints on activation in the face of competing demands from pathological and task-related cognitive activity.
Cognitive styles in individuals with bipolar disorders
Authors: SCOTT JAN , POPE MARIE
Published: July 2004

Background. Published studies of emotional processing and cognitive style in bipolar disorders tend to have small sample sizes or use non-clinical samples. Larger clinically representative studies are needed.

Method. Self-esteem, dysfunctional attitudes and personality style were compared in unipolar (N=16) and bipolar disorder (N=77); and then investigated in the different phases of bipolar disorder (remitted=26; depressed=38; hypomanic=13). One-year outcome was assessed in 36 bipolar subjects.

Results. Unipolar subjects and bipolar subjects differed significantly in their mean levels of negative self-esteem (unipolar=15·5; bipolar=12·7; P<0·05). Bipolar subjects with hypomania reported mean levels of dysfunctional beliefs that were higher than individuals in remission but lower than depressed subjects (remitted=136·7; depressed=153·8; hypomanic=144·8; P<0·05). Hypomanic subjects recorded the highest levels of negative as well as positive self-esteem. In the exploratory analysis of outcome, negative self-esteem (Exp [B] 1·91; 95% CI 1·11 to 3·32; P<0·05) was the most robust predictor of relapse.

Conclusions. There are similarities in the cognitive style of individuals with unipolar as compared to bipolar disorders. Cognitive style in hypomania represents a phase between remission and depression rather than the polar opposite of depression. The implications of these findings are considered for psychological and neural network models.
Neuroticism in adolescence and psychotic symptoms in adulthood
Authors: GOODWIN R. D. , FERGUSSON D. M. , HORWOOD L. J.
Published: July 2004

Background. The aims of this research were to examine the associations between the personality trait of neuroticism in adolescence and later psychotic symptoms, taking into account potential confounding factors.

Method. Data were gathered over the course of a longitudinal study of a birth cohort of New Zealand born young people (N=1265). Over the course of the study, data were gathered on: (a) neuroticism at age 14; (b) psychotic symptoms predominantly subclinical, assessed on the Symptom Checklist (SCL-90), at ages 18 and 21; (c) a range of potential confounding factors including measures of childhood adversity and co-morbid mental disorders.

Results. Young people in the highest quartile of neuroticism at age 14 had rates of psychotic symptoms that were two to three times higher than those in the lowest quartile. After statistical adjustment for confounding factors, including childhood adversity and co-morbid mental disorders, the association between neuroticism and later psychotic symptoms reduced but remained statistically significant (P<0·05). After adjustment for confounding, young people with high levels of neuroticism had rates of psychotic symptoms that were between 1·5 to 1·8 times higher than those with low levels of neuroticism.

Conclusions. Early neuroticism may be a precursor to the onset of psychotic symptoms. The mechanisms underlying this association are unclear, but may relate to overlapping features between prodromal phases of psychosis and items that measure neuroticism.
A quantitative genetic analysis of schizotypal personality traits
Authors: LINNEY Y. M. , MURRAY R. M. , PETERS E. R. , MacDONALD A. M. , RIJSDIJK F. , SHAM P. C.
Published: July 2004

Background. Previous twin studies investigating the heritability of schizotypy have often had limited power and have failed to measure the disorganization/social anxiety component.

Method. Seven hundred and thirty-three female twin pairs, drawn from the Institute of Psychiatry Volunteer Twin Register, completed the Oxford–Liverpool Inventory of Feelings and Experiences and the Peters et al. Delusions Inventory. Structural equation modelling was carried out on scores for MZ and DZ twin pairs.

Results. The best fitting models for all scales comprised additive genetic and unique environmental effects. Heritability was estimated at approximately 50% for most scales, although it was lower at 37% for the PDI scale. Multivariate structural equation model fitting revealed a best-fitting model in which additive genetic and unique environmental influences act through a single common pathway for Cognitive Disorganization, Unusual Experiences and the PDI, and through a separate common pathway for Cognitive Disorganization and Introvertive Anhedonia.

Conclusions. The various components of schizotypy are moderately heritable. Multivariate model fitting indicates that at least two latent factor structures are required to account for the covariation between the various components of schizotypy. The positive and negative components of schizotypy are relatively genetically independent, although each in turn may be related to Cognitive Disorganization.
Deliberate self-harm in Oxford, 1990–2000: a time of change in patient characteristics
Authors: HAWTON K. , HARRISS L. , HALL S. , SIMKIN S. , BALE E. , BOND A.
Published: July 2004

Background. Trends in deliberate self-harm (DSH) are important because they have implications for hospital services, may indicate levels of psychopathology in the community and future trends in suicide, and can assist in identification of means of suicide prevention.

Method. We have investigated trends in DSH and characteristics of DSH patients between 1990 and 2000 based on data collected through the Oxford Monitoring System for Attempted Suicide.

Results. During the 11-year study period 8590 individuals presented following 13858 DSH episodes. The annual numbers of persons and episodes increased overall by 36·3% and 63·1% respectively. Rates (Oxford City) declined, however, in the final 3 years. There were gender- and age-specific changes, with a rise in DSH rates in males aged [ges ]55 years and in females overall and those aged 15–24 years and 35–54 years. Repetition of DSH increased markedly during the study period. Antidepressant overdoses, especially of SSRIs, increased substantially. Paracetamol overdoses declined towards the end of the study period. Alcohol abuse, use of alcohol in association with DSH, and violence increased, especially in females, and the proportion of patients in current psychiatric care and misusing drugs also rose.

Conclusions. While overall rates of DSH did not increase markedly between 1990 and 2000, substantial changes in the characteristics of the DSH population and a rise in repetition suggest that the challenges facing clinical services in the management of DSH patients have grown.
High (15 Hz) and low (1 Hz) frequency transcranial magnetic stimulation have different acute effects on regional cerebral blood flow in depressed patients
Authors: LOO C. K. , SACHDEV P. S. , HAINDL W. , WEN W. , MITCHELL P. B. , CROKER V. M. , MALHI G. S.
Published: July 2004

Background. High and low frequency repetititve transcranial magnetic stimulation (rTMS) are both effective in treating depression but have contrary effects on motor cortical activity. This study aimed to understand further the mechanisms of action of high and low frequency rTMS by examining their acute effects on regional cerebral blood flow (rCBF) in depressed patients.

Method. Eighteen depressed subjects underwent brain single photon emission computerized tomography (SPECT) scanning using split-dose 99mTc-HMPAO, and were examined during sham and active rTMS to the left prefrontal cortex, at 15 Hz or 1 Hz (N=9 each). Relative rCBF changes were examined by statistical parametric mapping and by regions of interest analysis.

Results. High (15 Hz) frequency rTMS resulted in relative rCBF increases in the inferior frontal cortices, right dorsomedial frontal cortex, posterior cingulate and parahippocampus. Decreases occurred in the right orbital cortex and subcallosal gyrus, and left uncus. Low (1 Hz) frequency rTMS led to increased relative rCBF in the right anterior cingulate, bilateral parietal cortices and insula and left cerebellum. High frequency rTMS led to an overall increase, whereas low frequency rTMS produced a slight decrease, in the mean relative rCBF in the left dorsolateral prefrontal cortex.

Conclusions. High (15 Hz) and low (1 Hz) frequency rTMS led to different frontal and remote relative rCBF changes, which suggests different neurophysiological and possibly neuropsychiatric consequences of a change in frequency of rTMS.
Of genes and twins
Authors: KENDLER KENNETH S.
Published: July 2004

The two paradigms that now dominate the increasingly active field of psychiatric genetics – genetic epidemiology and gene-finding methods – are well illustrated by five papers in this issue of Psychological Medicine. Genetic epidemiology, which uses the classical ‘work-horse’ methods of family, twin and adoption studies, infers the action of genetic and environmental risk factors by observing the pattern of resemblance of traits or disorders in various classes of relatives. Methods that are utilized in genetic epidemiology can range from great simplicity, such as the odds ratio of a disorder in first-degree relatives of affected versus matched control probands, to substantial complexity, as seen in some advanced multivariate twin-family models (Truett et al. 1994). Of the quasi-experimental methods available to psychiatric geneticists that can tease apart the effects of genetic and shared-environmental factors (nature versus nurture), the twin method has become increasingly popular. This is probably due to the increasing availability of large population-based or volunteer twin registries (see the Oct 2002 issue of Twin Research on ‘Twin Registers as a Global Resource for Genetic Research’) that can be utilized to study psychiatric and drug abuse disorders. By contrast, due to changing social circumstances in most Western countries, adoption, even in the Scandinavian countries where most of the classic studies have been done, is becoming so rare that new adoption studies with younger age cohorts are hardly feasible. By contrast, gene-finding methods, which utilized variants of two different methods of linkage or association, have the goal of determining, on the human genome, the location and potential identity of susceptibility genes.
Sensitivity and specificity of neuropsychological tests for mild cognitive impairment, vascular cognitive impairment and Alzheimer's disease
Authors: DE JAGER C. A. , HOGERVORST E. , COMBRINCK M. , BUDGE M. M.
Published: July 2004

Background. Early diagnosis of dementia is important for those who might benefit from treatment. We designed a brief comprehensive neuropsychological test battery to help differentiate control subjects from patients with mild cognitive impairment (MCI) and dementia.

Method. The battery included tests of memory, attention, executive function, speed, perception and visuospatial skills. It was administered to subjects from the OPTIMA cohort: 51 controls, 29 with MCI, 60 with ‘possible’ or ‘probable’ Alzheimer's disease (AD) (NINCDS/ADRDA) and 12 with cerebrovascular disease (CVD). Mann–Whitney U tests were used to compare performance of controls with other diagnostic groups. The sensitivity and specificity of the tests were determined using Receiver Operating Characteristic curve analyses. The effects of age, gender and years of education on test performance were determined with Spearman's rank correlations.

Results. The AD group performed worse than controls on all tests except an attention task. The Hopkins Verbal Learning Test and The Placing Test for episodic memory showed significant discriminative capacity between controls and other groups. Attention and processing speed tests discriminated CVD from controls. Category fluency, episodic memory tests and the CLOX test for executive function distinguished MCI from AD. Spearman's correlations showed negative associations between age and processing speed. Years of education affected performance on all tests, except The Placing Test.

Conclusions. Certain neuropsychological tests have been shown to be sensitive and specific in the differential diagnosis of various types of dementia and may prove to be useful for detection of MCI.
Corpus callosum in first-episode patients with schizophrenia – a magnetic resonance imaging study
Authors: BACHMANN S. , PANTEL J. , FLENDER A. , BOTTMER C. , ESSIG M. , SCHRÖDER J.
Published: July 2004

Background. Morphometric studies on the corpus callosum (CC) in schizophrenia have yielded contradictory results. The aim of the present study was to investigate magnetic resonance imaging (MRI) abnormalities of the CC in first-episode patients with schizophrenic psychoses.

Method. We assessed volumetric MRI in 31 patients with diagnoses of schizophrenia, schizophreniform or schizoaffective disorder (DSM-IV) and a maximum exposure to neuroleptics of 2 weeks. As a control group, 12 healthy age- and sex-matched individuals were included in the study. A whole body scanner at 1.5 Tesla was used to obtain 3D T1- and T2-weighted MR datasets. The data were evaluated semi-automatically (intracranial volume, total brain volume) and manually (CC) with the software NMRwin.

Results. Patients had smaller CC and CC subdivisions than controls. Schizophrenic and unaffected women exhibited larger total CC and rostral subdivisions than men in both groups. Handedness did not exert an influence.

Conclusions. Our findings are in line with other in vivo morphometric studies on the CC in schizophrenia. The larger CC area in women may reflect general gender-related differences in CC size as described in healthy individuals.
Providing information about the effectiveness of treatment options to depressed people in the community: a randomized controlled trial of effects on mental health literacy, help-seeking and symptoms
Authors: JORM A. F. , GRIFFITHS K. M. , CHRISTENSEN H. , KORTEN A. E. , PARSLOW R. A. , RODGERS B.
Published: July 2004

Background. Many people who are depressed do not receive any professional help and their beliefs about the helpfulness of treatment do not always correspond with those of health professionals. To facilitate choices about treatment, the present study examined the effects of providing depressed people in the community with evidence on whether various treatment options work.

Method. A randomized controlled trial was carried out with 1094 persons selected at random from the community who screened positive for depressive symptoms and agreed to participate. Participants were mailed either an evidence-based consumer guide to treatments for depression or, as a control, a general brochure on depression. Outcomes were the rated usefulness of the information provided, changes in attitudes to depression treatments, actions taken to reduce depression, and changes in depressive symptoms, anxiety symptoms and disability.

Results. Participants rated the evidence-based consumer guide as more useful than the control brochure. Attitudes to some treatments changed. Improvements in symptoms and disability did not differ significantly between interventions.

Conclusion. Providing people who are depressed with evidence on which treatments work produces some changes in attitudes and behaviour. However, this intervention may need to be enhanced if it is to produce symptom change.
Cost-effectiveness of brief cognitive behaviour therapy versus treatment as usual in recurrent deliberate self-harm: a decision-making approach
Authors: BYFORD S. , KNAPP M. , GREENSHIELDS J. , UKOUMUNNE O. C. , JONES V. , THOMPSON S. , TYRER P. , SCHMIDT U. , DAVIDSON K. ,   ( POPMACT GROUP)
Published: July 2004

Background. Deliberate self-harm can be costly, in terms of treatment and subsequent suicide. Any intervention that reduces episodes of self-harm might therefore have a major impact on the costs incurred by service providers and the productivity losses due to illness or premature death.

Method. Four hundred and eighty patients with a history of recurrent deliberate self-harm were randomized to manual-assisted cognitive behaviour therapy (MACT) or treatment as usual. Economic data were collected from patients at baseline, 6 and 12 months, and these data were complete for 397 patients. Incremental cost-effectiveness was explored using the primary outcome measure, proportion of patients having a repeat episode of deliberate self-harm, and quality of life. The uncertainty surrounding costs and effects was represented using cost-effectiveness acceptability curves.

Results. Differences in total cost per patient were statistically significant at 6 months in favour of MACT (−£897, 95% CI −1747 to −48, P=0·04), but these differences did not remain significant at 12 months (−£838, 95% CI −2142 to 466, P=0·21). Nevertheless, exploration of the uncertainty surrounding these estimates suggests there is >90% probability that MACT is a more cost-effective strategy for reducing the recurrence of deliberate self-harm in this population over 1 year than treatment as usual. The results for quality of life were not conclusive.

Conclusion. Cost-effectiveness acceptability curves demonstrate that, based on the evidence currently available, to reject MACT on traditional grounds of statistical significance and to continue funding current practice has <10% chance of being the correct decision in terms of cost-effectiveness.
The Vulnerable Attachment Style Questionnaire (VASQ): an interview-based measure of attachment styles that predict depressive disorder
Authors: BIFULCO A. , MAHON J. , KWON J.-H. , MORAN P. M. , JACOBS C.
Published: July 2004

Background. The Vulnerable Attachment Style Questionnaire (VASQ) was developed to provide a brief self-report tool to assess adult attachment style in relation to depression and validated against an existing investigator-based interview (Attachment Style Interview – ASI). This paper describes the development and scoring of the VASQ and its relationship to poor support and major depression.

Method. Items for the VASQ reflected behaviours, emotions and attitudes relating to attachment relationship style, drawn directly from the ASI. The VASQ was validated against the ASI for 262 community-based subjects. Test–retest was determined on 38 subjects.

Results. Factor analysis derived two factors, labelled ‘insecurity’ and ‘proximity-seeking’. The VASQ insecurity dimension had highest mean scores for those with interview-based Angry-dismissive and Fearful styles and was significantly correlated with degree of interview-based insecurity. The proximity-seeking VASQ scores had highest mean for those with Enmeshed interview attachment style and was uncorrelated with ASI insecurity. VASQ scores were highly correlated with a well-known self-report measure of insecure attachment (Relationship Questionnaire) and text–retest reliability of the VASQ was satisfactory. The total VASQ score and the insecurity subscale proved highly related to poor support and to depressive disorder. This was not the case for the proximity-seeking subscale.

Conclusion. The VASQ is a brief self-report measure that distinguishes individuals with attachment styles vulnerable for depressive disorder. The use of the measure for screening in research and clinical contexts is discussed.
Association between clinically depressed subgroups, type of treatment and patient retention in the LIDO study
Authors: BECH P. , LUCAS R. , AMIR M. , BUSHNELL D. , MARTIN M. , BUESCHING D. ,   THE LIDO GROUP
Published: July 2004

Background. Few data are available with which to evaluate the association between depressed subgroups, type of treatment and patient retention during episodes of major depression.

Method. This observational study followed 1117 depressed patients over a 12-month period in the primary care setting of six different international sites. The patients were divided into three severity-linked subgroups: moderate to severe depression; moderate depression co-morbid with serious medical conditions; and mild depression.

Results. In general, a low dropout rate was found, with significant differences in the rates across the six sites. However, while there was no statistical significance in the association between the three subgroups of depression and overall dropout rates, we did find that older patients were less likely to drop out, more depressed patients were more likely to drop out, and if patients were on antidepressants they were less likely to drop out. Among the three subgroups of depression, patients with moderate depression co-morbid with serious medical conditions received the lowest amount of antidepressants and had the lowest quality of life.

Conclusion. Although the overall dropout rate in this study was found very low and did differ between the six sites, an association between the use of antidepressants and patient retention was seen. The group of patients with serious co-morbid medical conditions received fewer antidepressants even when the level of their depressive states was taken into consideration. This group was the least satisfied with treatment and had the lowest self-reported quality of life.
The challenge of evaluating the effectiveness of treatments for deliberate self-harm
Authors: HAWTON KEITH , SINCLAIR JULIA
Published: July 2004

Deliberate self-harm (DSH) is the most important factor associated with risk of suicide. It also poses a considerable burden on health and social services. Repetition of DSH after hospital presentation is common, with most studies reporting between 12 and 25% of patients repeating within a year and again presenting to hospital (Owens et al. 2002) and many more being involved in repeat episodes which do not bring them to clinical attention (Guthrie et al. 2001). Repetition itself increases the risk of a fatal outcome (Sakinofsky, 2000). The results of both psychosocial and pharmacological interventions to prevent repetition have been fairly disappointing (Hawton et al. 1998, 2000), although the findings of treatment trials have not all been negative. Dialectical behaviour therapy had a substantial initial impact on repetition of self-harm, although this did not persist in a treatment study of female patients with borderline personality disorders (Linehan et al. 1991) and depot flupenthixol reduced repetition in frequent self-harmers (Montgomery, 1987). A recent trial of brief psychotherapy was more effective than treatment as usual (Guthrie et al. 2001) and a meta-analysis of trials of problem-solving therapy suggested beneficial effects for depression, hopelessness and specific problems (Townsend et al. 2001).
Cognition in mania and depression
Authors: TAVARES J. V. TAYLOR , DREVETS W. C. , SAHAKIAN B. J.
Published: July 2004

The inclusion of cognitive symptoms in the DSM-IV criteria for major depressive and manic episodes highlight the importance of cognition in both of these psychiatric disorders (American Psychiatric Association, 1994). For example, criteria for diagnosis of these conditions include a diminished ability to concentrate and indecisiveness. In addition, numerous studies have demonstrated wide-ranging cognitive deficits in depression (for example Elliott et al. 1996; Purcell et al. 1997; Murphy et al. 2003) and mania (Goldberg et al. 1993; Murphy et al. 1999, 2001; Sweeney et al. 2000). These include deficits in early information processing (Tsourtos et al. 2002), recollection memory (MacQueen et al. 2002) and planning (Elliott et al. 1996) as well as affective biases (Murphy et al. 1999) and abnormal responses to negative feedback (Elliott et al. 1996, 1997; Murphy et al. 2003). Some residual deficits are also evident in a proportion of remitted subjects, even when controlling for mood (for example, Clark et al. 2002).
A methodology for fault diagnosis in robotic systems using neural networks
Authors: Vemuri Arun T. , Polycarpou Marios M.
Published: July 2004

Fault diagnosis plays an important role in the operation of modern robotic systems.
A number of researchers have proposed fault diagnosis architectures for robotic manipulators using the
model-based analytical redundancy approach. One of the key issues in the design of such fault diagnosis
schemes is the effect of modeling uncertainties on their performance. This paper investigates the problem of
fault diagnosis in rigid-link robotic manipulators with modeling uncertainties. A learning architecture with
sigmoidal neural networks is used to monitor the robotic system for off-nominal behavior due to faults.
The robustness, sensitivity, missed detection and stability properties of the fault diagnosis scheme are
rigorously established. Simulation examples are presented to illustrate the ability of the neural network
based robust fault diagnosis scheme to detect and accommodate faults in a two-link robotic manipulator.
Master-slave hand system of different structures, grasp recognition by neural network and grasp mapping
Authors: Wojtara Tytus , Nonami Kenzo , Shao Hui , Yuasa Ryohei , Amano Shingo , Nobumoto Yasukazu
Published: July 2004

This article is proposing a grasp recognition and grasp mapping method for a land mine clearance master-slave system. The system consists of a data glove and a powerful hydraulic hand. Because of the different structure of the master and slave hand a mapping from master grasp to slave grasp has to be implemented. The paper presents a grasp recognition method by Neural Network (NN) and a mapping method. The introduced mapping method allows the operator more intuitive grasping.
Stiffness Analysis and Design of a Compact Modified Delta Parallel Mechanism
Authors: Yoon Woo-Keun , Suehiro Takashi , Tsumaki Yuichi , Uchiyama Masaru
Published: July 2004

In our previous work, we developed a compact 6-DOF haptic interface as a master device which achieved an effective manual teleoperation. The haptic interface contains a modified Delta parallel-link positioning mechanism. Parallel mechanisms are usually characterized by a high stiffness, which, however, is reduced by elastic deformations of both parts and bearings. Therefore, to design such a parallel mechanism, we should analyze its structural stiffness, including elastic deformations of both parts and bearings. Then we propose a simple method to analyze structural stiffness in a parallel mechanism using bearings. Our method is based on standard concepts such as static elastic deformations. However, the important aspect of our method is the manner in which we combine these concepts and how we obtain the value of the elasticity coefficient of a rotation axis in a bearing. Finally, we design a modified Delta mechanism, with a well-balanced stiffness, based on our method of stiffness analysis.
A novel potential-based path planning of 3-D articulated robots with moving bases
Authors: Lin Chien-Chou , Pan Chi-Chun , Chuang Jen-Hui
Published: July 2004

This paper proposes a novel path planning algorithm of 3-D articulated robots with moving bases based on a generalized potential field model. The approach computes, similar to that done in electrostatics, repulsive forces and torques between charged objects. A collision-free path can be obtained by locally adjusting the robot configuration to search for minimum potential configurations using these forces and torques. The proposed approach is efficient since these potential gradients are analytically tractable. In order to speedup the computation, a sequential planning strategy is adopted. Simulation results show that the proposed algorithm works well, in terms of collision avoidance and computation efficiency.
A globally convergent tracking controller for the X4 flyer rotor craft for reference trajectories with positive thrust
Authors: Driessen Brian J. , Robin Alexandre L.
Published: July 2004

In this paper we present a globally convergent and ultimately exponentially convergent tracking controller for an X4 Flyer rotor craft. The desired or reference trajectory is restricted in one way: its scalar thrust must be uni signed and bounded away from zero. The proposed controller is a two phase one. Phase I converges the attitude (orientation) error and thrust error to zero globally and ultimately exponentially. Phase II is a position tracking and relative yaw angle tracking controller, which is not globally convergent by itself. By carefully postponing a switch from Phase I to Phase II, we are able to assure that Phase II will ultimately drive the position error and relative yaw angle error to zero exponentially. In problem-statement/theorem/proof format, we define the system, the control objective, the proposed controller, and a rigorous proof that the controller maintains boundedness of all closed loop signals and provides global convergence of the tracking error to zero and also ultimately exponential convergence of the tracking error to zero.
Global robust output feedback tracking control of robot manipulators
Authors: Dixon W. E. , Zergeroglu E. , Dawson D. M.
Published: July 2004

This paper addresses the problem of global output feedback, link position tracking control of robot manipulators. Specifically, a robust, Lyapunov-based controller is designed to ensure that the link position tracking error is globally uniformly ultimately bounded despite the fact that only link position measurements are available in the presence of incomplete model information (i.e., parametric uncertainty and additive bounded disturbances).
Adaptive Impedance Control of Robot Manipulators based on Function Approximation Technique
Authors: Chien Ming-Chih , Huang An-Chyau
Published: July 2004

This paper presents an adaptive impedance control scheme for an $n$-link constrained rigid robot manipulator without using the regressor. In addition, inversion of the estimated inertia matrix is also avoided and the new design is free from end-point acceleration measurements. The dynamics of the robot manipulator is assumed that all of the matrices in robot model are unavailable. Since these matrices are time-varying and their variation bounds are not given, traditional adaptive or robust designs do not apply. The function approximation technique is used here to represent uncertainties in some finite linear combinations of the orthogonal basis. The dynamics of the output tracking can thus be proved to be a stable first order filter driven by function approximation errors. Using the Lyapunov stability theory, a set of update laws is derived to give closed loop stability with proper tracking performance. A 2 DOF planar robot with environment constraint is used in the computer simulations to test the efficacy of the proposed scheme.
Contribution to the dynamic study of humanoid robots interacting with dynamic environment
Authors: Vukobratović Miomir , Potkonjak Veljko , Rodić Aleksandar
Published: July 2004

The questions when and why one needs to use mathematical models, and especially the models of dynamics, represent still an unresolved issue. A general answer would be that dynamic modelling is needed as a tool when designing structure of the system and its control unit. In this case we talk about simulation. The other application is in on-line control of the system – the so-called dynamic control. While in simulation one generally uses the best available model, the control can be based on a reduced dynamics, depending on a particular task. The aim of this paper was to highlight the problems important for the dynamics of humanoids and their dynamic environment.
On the direct problem singularities of a class of 3-DOF parallel manipulators
Authors: Di Gregorio R.
Published: July 2004

The 3-PS structure features one rigid body (platform) connected to another rigid body (base) by means of three kinematic chains (limbs) of type PS (P and S stand for prismatic pair and spherical pair, respectively). All the 3-degree-of-freedom parallel manipulators with three connectivity-5 limbs, each one constituted of one passive (i.e. not actuated) prismatic pair, one passive spherical pair and one actuated kinematic pair of any type, become 3-PS structures when the actuated pairs are locked. Direct kinematics of this class of manipulators is tied to the properties of the 3-PS structure. In particular, the direct position analysis is tied to the assembly modes of the 3-PS structure; whereas the determination of the singularities of the direct instantaneous problem is tied to the determination of the singular geometries of the 3-PS structure, where instantaneous relative motions between platform and base are possible. The solution of these two problems is necessary both for designing the manipulators and for controlling them during motion. This paper deal with the determination of the singular geometries of the 3-PS structure.
Base invariance of the manipulability index
Authors: Gotlih Karl , Troch Inge
Published: July 2004

The manipulability index suggested by Yoshikava is an important tool for the design of mechanisms and their control. It represents a quantitative measure of the functionality and the ability for realizing some tasks or groups of tasks. This index is some kind of performance measure and should be taken into consideration in the design phase of a mechanism and also in the design of control algorithms.

In this paper two important properties of the manipulability index are investigated. The first part of the present work demonstrates that manipulability of a mechanism is independent of task space coordinates. In the second part, a proof of the independency of the manipulability index on the first DOF is given.

This invariance is important for simplification of the mechanism's Jacobian matrix and gives excellent insight into the dependences of configuration space coordinates on this index. Moreover, it proves that the manipulability index is determined only by relative positions of the mechanism itself and by the mechanism's geometry.

Finally, the properties of the manipulability index are illustrated by some examples for fundamental open kinematical chain structures.
EP-WAR3 biped robot for climbing and descending stairs
Authors: Figliolini Giorgio , Ceccarelli Marco
Published: July 2004

A biped walking robot, named EP-WAR3 (Electro-Pneumatic-Walking-Robot), has been designed, built and tested at LARM (Laboratory of Robotics and Mechatronics) in Cassino. EP-WAR3 is provided with a suitable binary pneumatic actuation in order to be controlled through a common PLC (Programmable-Logic-Controller) as an event-based system in an on/off environment. The walking stability of the biped robot is obtained by using suction-cups, which are installed on the underside of each foot. EP-WAR3 is able to walk along a straight line with two different step sizes, turn right and left, and to climb and to descend stairs. A suitable motion analysis and programming technique of the PLC controller is proposed in order to obtain suitable walking capabilities and flexibility of the robot.
Autonomous navigation of indoor mobile robots using a global ultrasonic system
Authors: Yi Soo-Yeong , Choi Byoung-Wook
Published: July 2004

Autonomous navigation of an indoor mobile robot, using the global ultrasonic system, is presented in this paper. Since the trajectory error of the dead-reckoning navigation increases significantly with time and distance, the autonomous navigation system of a mobile robot requires self-localization capa-bility in order to compensate for trajectory error. The global ultrasonic system, consisting of four ultrasonic generators fixed at a priori known positions in the work space and two receivers mounted on the mobile robot, has a similar structure to the well-known satellite GPS(Global Positioning System), which is used for the localization of ground vehicles. The EKF (Extended Kalman Filter) algorithm is utilized for self-localization and autonomous navigation, based on the self-localization algorithm is verified by experiments performed in this study. Since the self-localization algorithm is efficient and fast, it is appropriate for an embedded controller of a mobile robot.
Ponderomotive narrow continuum (NCp) component in stimulated electromagnetic emission spectra
Authors: Frolov V. L. , Sergeev E. N. , Komrakov G. P. , Stubbe P. , Thidé B. , Waldenvik M. , Veszelei E. , Leyser T. B.
Published: July 2004

We present experimental results concerning the ponderomotive narrow continuum (NCp) in stimulated electromagnetic emission spectra, generated in the ionospheric F region plasma by a powerful O mode electromagnetic wave. It is found that the generation of the NCp is determined by the development of the parametric decay instability in the initial stage of the interaction of the HF pump wave with the plasma. The dependence of the NCp temporal and spectral characteristics on pump power, pump frequency, time of day, and pump schedule as well as its gyrofeatures are considered. A possible mechanism for the NCp generation is discussed.
Energetic neutral atoms from Jupiter measured with the Cassini magnetospheric imaging instrument: Time dependence and composition
Authors: Mitchell D. G. , Paranicas C. P. , Mauk B. H. , Roelof E. C. , Krimigis S. M.
Published: July 2004

During the Cassini spacecraft flyby of Jupiter in late 2000/early 2001, the Ion and Neutral Camera (INCA, one of three sensors that make up the Cassini Magnetospheric Imaging Instrument (MIMI)) obtained the first ever images of Jupiter's magnetosphere in energetic neutral atom (ENA) flux. These emissions are dominated by hydrogen atoms in the energy range from a few to 100 keV, emitted from the planet's exosphere and neutral gas tori near the inner Galilean satellites. Heavier ions (likely a mixture of oxygen and sulfur) comprise a significant fraction of the ENA flux, as well. Neutral atom energy spectra escaping the magnetosphere are computed from measurements made at about 145 RJ from the planet. From these spectra we show that there is significant emission of oxygen and/or sulfur atoms from the Jovian magnetosphere in the 0.1–1.0 MeV total energy range. We also show that ENA flux falls off approximately with the square of radial distance from Jupiter. In three separate energy channels, we find that during a period of about 80 days (mostly before closest approach), FR2 is constant to lowest order but do observe variations close to the statistical limit of our measurement. We estimate a source rate of ∼1026/s H in the 10–100 keV range and ∼5 × 1025/s O in the 100–1000 keV energy range.
Heliospheric filtration of interstellar heavy atoms: Sensitivity to hydrogen background
Authors: Müller H.‐R. , Zank G. P.
Published: July 2004

Heavy elements including He, C, N, O, Ne, and Ar are present in the interstellar medium surrounding the heliosphere. They form the most important source for heavy pickup ions and anomalous cosmic rays in the heliosphere. Kinetic numerical models are used to study the entrance and the heliospheric distribution of neutrals and singly charged ions of these six heavy element species as they interact through charge exchange with the neutral and ionized hydrogen of the heliosphere. Since the interstellar hydrogen parameters are not known precisely, three different representative hydrogen heliospheric models are used to study the heavy element distribution, and the sensitivity of key results, including filtration ratios of heavy elements and increased heavy neutral densities (walls), to the different hydrogen backgrounds is established. The key neutral heavy element results are largely insensitive to the specifics of the hydrogen background. The location and extent of neutral element features depends sensitively on the hydrogen background, as do all the heavy ion results.
A gap in the Indo‐Pacific warm pool over the South China Sea in boreal winter: Seasonal development and interannual variability
Authors: Liu Qinyu , Jiang Xia , Xie Shang‐Ping , Liu W. Timothy
Published: July 2004

The Indo‐Pacific warm water pool in boreal winter shows a conspicuous gap over the South China Sea (SCS) where sea surface temperature (SST) is considerably lower than over the oceans both to the west and east. The formation mechanisms for the climatology and interannual variability of SCS SST in boreal winter are investigated using a suite of new satellite measurements. The winter SCS is divided into two parts by the axis of the maximum northeasterly monsoonal winds. The positive wind curl in the southeastern half of the ocean drives a cyclonic gyre circulation in the deep basin. As its western boundary current, an intense southward flow is found south of Vietnam on the continental slope separating the Sunda Shelf to the west and the deep SCS basin to the east. This slope current exceeds 0.5 m s−1 in speed and advects cold water from the north. This cold advection results in a distinct cold tongue in the winter SST climatology. Both the slope current and the cold tongue are strongest in November to February. This winter cold tongue displays considerable interannual variability that is highly correlated with eastern equatorial Pacific SST. In an El Niño the winter monsoon weakens, causing the SCS ocean circulation to spin down. The reduced western boundary current and its thermal advection result in a warming in the SCS winter cold tongue. Both SST variance and its correlation with the El Niño‐Southern Oscillation peak along the climatological cold tongue indicate that ocean dynamics are an important player in SCS climate variability.
Aeolian sediment transport pathways and aerodynamics at troughs on Mars
Authors: Bourke Mary C. , Bullard Joanna E. , Barnouin‐Jha Olivier S.
Published: July 2004

Interaction between wind regimes and topography can give rise to complex suites of aeolian landforms. This paper considers aeolian sediment associated with troughs on Mars and identifies a wider range of deposit types than has previously been documented. These include wind streaks, falling dunes, “lateral” dunes, barchan dunes, linear dunes, transverse ridges, sand ramps, climbing dunes, sand streamers, and sand patches. The sediment incorporated into these deposits is supplied by wind streaks and ambient Planitia sources as well as originating within the trough itself, notably from the trough walls and floor. There is also transmission of sediment between dunes. The flow dynamics which account for the distribution of aeolian sediment have been modeled using two‐dimensional computational fluid dynamics. The model predicts flow separation on the upwind side of the trough followed by reattachment and acceleration at the downwind margin. The inferred patterns of sediment transport compare well with the distribution of aeolian forms. Model data indicate an increase of wind velocity by ∼30% at the downwind trough margin. This suggests that the threshold wind speed necessary for sand mobilization on Mars will be more frequently met in these inclined locations.
Effect of precursor mineralogy on the thermal infrared emission spectra of hematite: Application to Martian hematite mineralization
Authors: Glotch T. D. , Morris R. V. , Christensen P. R. , Sharp T. G.
Published: July 2004

Observations from the Thermal Emission Spectrometer (TES) instrument aboard the Mars Global Surveyor (MGS) spacecraft led to the discovery of two isolated deposits of gray, crystalline hematite located in Meridiani Planum and Aram Chaos and several smaller deposits in Valles Marineris. Several pathways for formation of these hematite deposits have been proposed, involving both aqueous and nonaqueous processes. This work uses the precise shape and position of spectral features in the Martian hematite thermal emission spectrum to constrain hematite formation pathways. Thermal infrared emission spectra, X‐ray powder diffraction patterns, Mössbauer spectra, and transmission electron microscope (TEM) photomicrographs were obtained for synthetic and natural hematite samples derived by (1) dehydroxylation of fine‐grained goethite and (2) oxidation of magnetite. Collectively, the instrumental analyses show that the mineralogical composition and crystal morphology of precursor samples and the time and temperature conditions under which decomposition to hematite occur determine the crystallinity and crystal morphology of the hematite product. Comparison of laboratory and MGS‐TES spectra shows that the Martian hematite spectra correspond closely with a synthetic hematite sample derived by pseudomorphic and topotactic dehydroxylation of goethite at 300°C. Spectra of goethite‐precursor samples dehydroxylated at higher temperatures provide increasingly poor fits. Spectra of hematite samples derived by high‐temperature thermal oxidation of magnetite are also poorer fits to the Martian hematite spectrum. Thermal emission spectra of goethites heated at lower temperatures are characterized by the spectral signatures of both hematite and goethite and are not consistent with the Martian spectra. The characteristic that distinguishes the synthetic hematite sample with the Mars‐like spectral signature from the other synthetic hematite samples is the high proportion of crystal surfaces that are crystallographic {001} faces (c faces) for the former but not the latter. The high proportion of {001} face area results because the largest surface of the lath‐shaped hematite particles is the (001) face, as determined by TEM. Thus a possible formation pathway for hematite in Meridiani Planum, Aram Chaos, and Valles Marineris is precipitation of goethite from aqueous solutions as lath‐shaped crystals, possibly as a stain, cement, and/or massive deposit, followed by pseudomorphic and topotactic dehydroxylation to hematite at temperatures below ∼300°C.