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Biomedical subjects

M S Atkins

Publications and source records attributed to M S Atkins.

At least 19 recordsLinked to original sources
PubMed2005

Evaluating different radiology workstation interaction techniques with radiologists and laypersons.

This paper presents a new methodology for evaluating radiology workstation interaction features, using lay subjects to perform a radiology look-alike task with artificial stimuli. We validated this methodology by evaluating two different workstation interaction techniques with two groups of subjects: laypersons and radiologists, using a set of artificial targets to simulate the reading of a diagnostic examination. Overall, the results from the two groups of subjects performing the same tasks were very similar. Both groups showed significantly faster response times using a new interaction technique, and the mouse clicks for both groups were very similar, showing that all the subjects mastered the style of interaction in a similar way. The errors made by both groups were comparable. These results show that it is possible to test new workstation interaction features using look-alike radiological tasks and inexperienced laypersons, and that the results do transfer to radiologists performing the same tasks.

Computer Systems↗
PubMed2001

Exploring presentation methods for tomographic medical image viewing.

This paper explores the presentation of tomographic medical images on a computer screen. Limitations of the computer screen are apparent, as even a very large computer monitor cannot display an entire study consisting of dozens of images at once. Our objective is to propose filmless computer presentation methods for these images, in particular for magnetic resonance images. First, we observe the magnetic resonance image analysis task in the traditional light screen environment where presentation of many images has always been possible. We then propose solutions for meeting requirements in the computer environment. After implementation of these solutions we obtain user feedback on alternatives in order to determine feasibility and preference. Observations reveal three requirement categories: user control of film management, navigation of images and image series, and simultaneous availability of detail and context. We developed a framework of detail-in-context-technique parameters for the purpose of viewing tomographic medical images and presented our solution directions to the radiologists for feedback. Results from the user feedback study support the feasibility of the proposed approaches and clearly indicate the importance of presentation issues in the development of medical imaging viewing systems.

Equipment Design↗
PubMed2001

Wavelet-based space-frequency compression of ultrasound images.

This paper describes the compression of grayscale medical ultrasound images using a recent compression technique, i.e., space-frequency segmentation (SFS). This method finds the rate-distortion optimal representation of an image from a large set of possible space-frequency partitions and quantizer combinations and is especially effective when the images to code are statistically inhomogeneous, which is the case for medical ultrasound images. We implemented a compression application based on this method and tested the algorithm on representative ultrasound images. The result is an effective technique that performs better than a leading wavelet-transform coding algorithm, i.e., set partitioning in hierarchical trees (SPIHT), using standard objective distortion measures. To determine the subjective qualitative performance, an expert viewer study was run by presenting ultrasound radiologists with images compressed using both SFS and SPIHT. The results confirmed the objective performance rankings. Finally, the performance sensitivity of the space-frequency codec is shown with respect to several parameters, and the characteristic space-frequency partitions found for ultrasound images are discussed.

Algorithms↗
PubMed2000

Ancyromonadida: a new phylogenetic lineage among the protozoa closely related to the common ancestor of metazoans, fungi, and choanoflagellates (Opisthokonta).

Molecular and morphological evidence points to the ancyromonad Ancyromonas as a plausible candidate for the closest relative to the common ancestor of metazoans, fungi, and choanoflagellates (the Opisthokonta). Using 18S rDNA sequences from most of the major eukaryotic lineages, maximum-likelihood, minimum-evolution, and maximum-parsimony analyses yielded congruent phylogenies supporting this hypothesis. Combined with ultrastructural similarities between Ancyromonas and opisthokonts, the evidence presented here suggests that Ancyromonas may form an independent lineage, the Ancyromonadida Cavalier-Smith 1997, closer in its relationship to the opisthokonts than is its nearest protist relatives, the Apusomonadida. However, the very low bootstrap support for deep nodes and hypothesis testing indicate that the resolving power of 18S rDNA sequences is limited for examining this aspect of eukaryotic phylogeny. Alternate branching positions for the Ancyromonas lineage cannot be robustly rejected, revealing the importance of ultrastructure when examining the origins of multicellularity. The future use of a multigene approach may additionally be needed to resolve this aspect of eukaryotic phylogeny.

Animals↗
PubMed1999

Adopted children's behavior problems: a review of five explanatory models.

Although the majority of adopted children are well-adjusted, adopted children evidence proportionately more behavior problems when compared to nonadopted children in both clinic and nonclinic populations. An extensive literature examining behavioral, diagnostic, and demographic characteristics of adopted children has provided several plausible explanations for the high rate of behavior problems among adopted children. In this review, the existing literature is organized into five explanatory models: (a) genetic or "biosocial" factors, (b) pathogenesis of the adoption process, (c) long-term effects of impaired preadoption childrearing, (d) referral bias in adoptive parents, and (e) impaired adoptive parent-adoptee relations. We conclude that evidence for each model is mixed at best. Especially noteworthy is the mixed results for genetic or biosocial studies and the relative absence of studies focused on identifying factors associated with disruptions in the adoptive parent-adoptee relationship. We propose that a psychosocial model to explain the high rate of behavior problems among adopted children is highly plausible and further suggest that it may be time for a new awareness and appreciation for the normative aspects of adoption. An overview of parenting and family characteristics associated with risk factors for antisocial behavior is provided as a guide for future research.

Adolescent↗
PubMed1998

An ecological model for school-based mental health services for urban low-income aggressive children.

An ecological model for school-based mental health services that targets urban low-income aggressive children--a highly vulnerable and underserved population--is presented. The goals of the model are to increase children's and teachers' involvement in the delivery of services and to increase the integration of these services into existing school resources and activities. The model proposes that mental health service providers work in collaboration with teachers to deliver services that (1) can be managed by existing school resources and personnel, (2) are related to empirically based factors associated with reduced aggression and increased social functioning, and (3) are group administered to increase the number of children served and to reduce stigmatization associated with mental health services. The model is individualized and flexible by acknowledging that contexts for aggression differ across classrooms and children and by providing services specific to those contexts. Two studies are presented illustrating the application of this model to decrease aggression and increase academic engagement in low-income urban public schools.

Achievement↗
PubMed1998

Fully automatic segmentation of the brain in MRI.

A robust fully automatic method for segmenting the brain from head magnetic resonance (MR) images has been developed, which works even in the presence of radio frequency (RF) inhomogeneities. It has been successful in segmenting the brain in every slice from head images acquired from several different MRI scanners, using different-resolution images and different echo sequences. The method uses an integrated approach which employs image processing techniques based on anisotropic filters and "snakes" contouring techniques, and a priori knowledge, which is used to remove the eyes, which are tricky to remove based on image intensity alone. It is a multistage process, involving first removal of the background noise leaving a head mask, then finding a rough outline of the brain, then refinement of the rough brain outline to a final mask. The paper describes the main features of the method, and gives results for some brain studies.

Brain↗
PubMed1996

A revised teacher rating scale for reactive and proactive aggression.

A teacher rating scale of reactive aggression, proactive aggression, and covert antisocial behavior was evaluated in a normative sample of third- to fifth-grade predominantly white lower middle class boys (N = 186). Factor analysis revealed independent and internally consistent Reactive Aggression (six reactive items), and Proactive Aggression (five proactive items, five covert items) factors. Although the factors were intercorrelated (r = .67), and each factor was significantly correlated with negative peer social status (r = .26 for each, controlling for grade), the independence of the factors was supported by the unique relation of Reactive Aggression with in-school detentions (r = .31), controlling for Proactive Aggression and grade. These results supported the reliability and validity of Reactive and Proactive Aggression as rated by teachers, which should facilitate further research of these constructs.

Aggression↗
PubMed1996

Proton dose monitoring with PET: quantitative studies in Lucite.

The feasibility of using PET for proton dose monitoring is examined here in detail. First experimental studies in a Lucite phantom have been performed at the medical TRIUMF proton beamline for proton energies of 62 MeV and 110 MeV. The proton dose delivered to the phantom ranged from 16 Gy up to 317 Gy. The induced activity was analysed 20-40 min after the irradiation with a PET scanner. The obtained depth activity profiles were compared to our calculation based on a model using available isotope production cross-section data. Both the observed absolute count rates and the activity profiles were found to agree very well with this model. Effects such as proton range straggling, inelastic nuclear interactions and the energy spectrum of the emitted positrons were studied in detail and found to change the activities by 5-10%. The lateral deposition of dose in the phantom could be very well localized by the induced activity. However, the spatial correlation between dose depth profiles and depth activity profiles was found to be poor, hence the extraction of isodose profiles from activity profiles seems to be very difficult.

Carbon↗
PubMed1993

Instrumental and hostile aggression in childhood disruptive behavior disorders.

An analogue task of instrumental and hostile aggression during a competitive game was evaluated in a sample of clinically-referred 8- to 12-year-old aggressive boys. Similar to a prior task in a normative sample (Hoving, Wallace, & La Forme, 1979), both types of aggression increased during provocation as compared to baseline, indicating the success of the provocation manipulation, with moderate correlations between the two aggressive responses. The aggressive group with attention-deficit hyperactivity disorder (ADHD) and the aggressive group without ADHD each had higher rates of instrumental aggression than controls. Only the aggressive/ADHD group had higher rates of hostile aggression than controls. Parent Child Behavior Checklist ratings indicated a modest but significant unique relationship between instrumental aggression and delinquency. The high rate of both types of aggression in the aggressive/ADHD group suggests that comorbid ADHD and aggression may result in qualitative differences in aggressive behavior. The high rate of hostile aggression in the aggressive-ADHD group supports theoretical assumptions regarding the relationship of hostile aggression to poor impulse control.

Aggression↗
PubMed1993

Distinguishing instrumental and hostile aggression: does it make a difference?

An analogue task of instrumental and hostile aggression during a competitive game, modified to minimize overlap between aggressive responses, was evaluated in 8- to 14-year-old clinically referred boys (n = 33). Postgame interviews indicated that the hostile response, an aversive noise, was perceived by over 80% of subjects as hostile and not instrumental. In contrast, the instrumental response, blocking the opponent's game, was perceived about equally as having instrumental and hostile functions. The hostile aggressive response was uniquely correlated with continuous performance task impulsive commission errors (r = .51), which supported the theoretical relation of hostile aggression to poor impulse control. These results suggest that instrumental and hostile aggression can be distinguished and when precisely defined are distinct in theoretically important ways.

Adolescent↗
PubMed1993

Assessing parents' willingness to pursue treatment for children with attention-deficit hyperactivity disorder.

OBJECTIVE: This study investigated parents' willingness to pursue treatment for attention-deficit-hyperactivity-disorder (ADHD). METHOD: A self-administered questionnaire (the ADHD Knowledge and Opinion Scale--AKOS) was developed and administered to a sample of 116 families attending an outpatient ADHD clinic. Socioeconomic status, parenting stress, family adaptability and cohesion, degree of child's externalizing behavior, and treatment history were obtained for each family. RESULTS: Parents' willingness to use medication or to pursue counseling were not related to family factors. History of the child receiving medication was mildly correlated with willingness to use medication. History of counseling was mildly correlated with willingness to use medication and to pursue counseling. Mothers who viewed their family as "enmeshed" reported significantly higher sense of competence than those viewing the family as "connected" or "disengaged." CONCLUSION: The AKOS is an instrument that may help clinicians identify and address parents' concerns about treatment for ADHD as well as parents' perceptions about their parenting skills.

Adaptation, Psychological↗
PubMed1991

School-based assessment of attention deficit-hyperactivity disorder.

Schools are uniquely situated to provide information relevant to the assessment and treatment of Attention Deficit-Hyperactivity Disorder (ADHD) across a variety of tasks, settings, and observers. The importance of the school setting to the assessment and treatment of ADHD has resulted in the development of numerous measures appropriate for such assessment, but few guidelines for their use. The purpose of this article is to describe school-based assessment procedures and their relationship to ADHD. These procedures include teacher rating measures, direct observations in classrooms and on playgrounds, peer rating and sociometric measures, and permanent product measures such as academic performance. It is recommended that school-based assessment of ADHD involve the concurrent use of multiple measures to assess adequately the wide variety of symptoms associated with this disorder. It is further recommended that assessment serve the purpose of determining treatment efficacy to avoid unwarranted preoccupation with diagnostic issues that are as yet unresolved. The components of a comprehensive school-based assessment of ADHD are described, and their relationship to school-based treatment is discussed.

Attention Deficit Disorder with Hyperactivity↗
PubMed1989

The differential validity of teacher ratings of inattention/overactivity and aggression.

The ability of school-based measures of child behavior to predict differentially the IOWA Conners teacher rating scale Inattention/Overactivity (IO) and Aggression (A) factors was evaluated in a sample of 71 school-aged boys. Multiple measures and multiple methods of assessment were utilized to provide a comprehensive assessment of social and academic behavior. These included direct observations of children in the classroom and on the playground, examination of the organization of children's desks, measures of academic performance, peer nominations of popularity and rejection, and sociometric ratings using the Pupil Evaluation Inventory. Despite moderately high correlations between the teacher rating factors (r = .60), considerable evidence was provided for differential validity on measures of academic performance, peer rating measures, and measures of disruptive or inappropriate classroom and playground behavior. These differences between IO and A factors indicated that the factors were logically independent in important ways, supporting prior work validating separate hyperactivity and aggression dimensions.

Achievement↗
PubMed1989

Post-traumatic stress in sexually abused, physically abused, and nonabused children.

This investigation compared the rates of post-traumatic stress disorder symptoms across sexually abused, physically abused, and nonabused psychiatrically hospitalized children matched for age, sex, and socioeconomic status. Among the sexually abused children, 20.7% met diagnostic criteria for post-traumatic stress disorder compared with 6.9% of the physically abused and 10.3% of the nonabused children. Although these overall rates were not significantly different across groups, they were significantly high to reinforce the need for further study of post-traumatic stress in childhood. Further, significant symptom rate differences across groups were found with respect to specific post-traumatic stress symptoms. Specifically, sexually abused children exhibited significantly higher rates of inappropriate sexual behaviors than either the physically abused or nonabused children. In addition, both the sexually abused and physically abused groups showed a tendency to exhibit more avoidant/dissociative symptoms as compared to the nonabused children. Results are discussed in terms of their clinical and research implications.

Arousal↗
PubMed1988

A psychometric study of positive and negative nominations and the pupil evaluation inventory.

Two peer evaluation measures, the Pupil Evaluation Inventory (PEI) and positive and negative nominations were compared in a sample of 260 children in grades 1 to 5. Stabilities of the measures were assessed over a 4-month period. In the total sample, PEI factors and negative nominations were more stable than positive nominations, and PEI Aggression and Withdrawal scores were more stable than negative nominations. PEI Aggression and Withdrawal scores were more stable in grades 3 and 5 than in grade 1, and the Likability factor was more stable in grades 2 to 5 than in grade 1. Negative nominations were most strongly correlated with the PEI Aggression factor, and positive nominations were more strongly correlated with Likability than with Aggression. Implications for the use of these nomination measures are discussed.

Aggression↗