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PubMed2005

Use of modulated excitation signals in medical ultrasound. Part I: Basic concepts and expected benefits.

This paper, the first from a series of three papers on the application of coded excitation signals in medical ultrasound, discusses the basic principles and ultrasound-related problems of pulse compression. The concepts of signal modulation and matched filtering are given, and a simple model of attenuation relates the matched filter response with the ambiguity function, known from radar. Based on this analysis and the properties of the ambiguity function, the selection of coded waveforms suitable for ultrasound imaging is discussed. It is shown that linear frequency modulation (FM) signals have the best and most robust features for ultrasound imaging. Other coded signals such as nonlinear FM and binary complementary Golay codes also have been considered and characterized in terms of signal-to-noise ratio (SNR) and sensitivity to frequency shifts. Using the simulation program Field II, it is found that in the case of linear FM signals, a SNR improvement of 12 to 18 dB can be expected for large imaging depths in attenuating media, without any depth-dependent filter compensation. In contrast, nonlinear FM modulation and binary codes are shown to give a SNR improvement of only 4 to 9 dB when processed with a matched filter. Other issues, such as depth-dependent matched filtering and use of filters other than the matched filter (inverse and Wiener filters) also are addressed.

Humans↗
PubMed2002

Black and Hispanic veterans in intensive VA treatment programs for Posttraumatic Stress Disorder.

OBJECTIVES: This study examines differences in treatment process and outcomes among minority veterans treated in specialized intensive VA programs for war-related Posttraumatic Stress Disorder (PTSD). DESIGN: A concurrent panel study assessing four different types of intensive PTSD treatment program. SUBJECTS: Black (n = 2,906; 23.4%), Hispanic (n = 661, 5.3%), and white veterans. METHODS: Hierarchical linear modeling was used to compare black and Hispanic veterans with white veterans on admission characteristics, treatment process, and outcomes, overall, and to determine whether treatment in three newer types of programs, each designed to improve efficiency, was associated with in changes in minority group experiences. RESULTS: At the time of program admission, black patients had less education, were less likely to be married or to receive VA compensation, and had more severe alcohol and drug problems, but had less severe PTSD symptoms than either white patients or Hispanic patients. There were no differences among groups on 8 of 11 measures of treatment process or outcome but black patients showed greater improvement than white patients on one measure of PTSD symptoms and Hispanic patients were more satisfied with their treatment than white patients although they showed smaller gains in employment income. There were few changes associated with newer program types: gains for minorities were observed on three measures and losses on two. CONCLUSIONS: Using data from a large national sample, this study found little evidence of systematic differences in either treatment process or outcome between white, black, and Hispanic patients overall, or in association with the implementation of more efficient program types.

Adult↗
PubMed2001

Tsukuba BB: a branch and bound algorithm for local multiple alignment of DNA and protein sequences.

In this paper we present a branch and bound algorithm for local gapless multiple sequence alignment (motif alignment) and its implementation. The algorithm uses both score-based bounding and a novel bounding technique based on the "consistency" of the alignment. A sequence order independent search tree is used in conjunction with a technique for avoiding redundant calculations inherent in the structure of the tree. This is the first program to exploit the fact that the motif alignment problem is easier for short motifs. Indeed, for a short fixed motif width, the running time of the algorithm is asymptotically linear in the size of the input. We tested the performance of the program on a dataset of 300 E. coli promoter sequences and a dataset of 85 lipocalin protein sequences. For a motif width of 4, the optimal alignment of the entire set of sequences can be found. For the more natural motif width of 6, the program can align 21 sequences of length 100, more than twice the number of sequences which can be aligned by the best previous exact algorithm. The algorithm can relax the constraint of requiring each sequence to be aligned, and align 105 of the 300 promoter sequences with a motif width of 6. For the lipocalin dataset, we introduce a technique for reducing the effective alphabet size with a minimal loss of useful information. With this technique, we show that the program can find meaningful motifs in a reasonable amount of time by optimizing the score over three motif positions.

Algorithms↗
PubMed1996

[Spontaneous and visually-induced oculomotor reactions in microgravity (Results of Austrian-Russian Experiment "Optovert" performed within the frame of program "Austromir", part II)].

Results of investigation of spontaneous and induced by vertical linear and sinusoid optokinetic stimulation oculomotor reactions in short- and long-term space missions are reported. Adaptation to microgravity was shown to be associated with rearrangement in sensory interactions even on a background of good subjective well-being and absence of abnormal autonomous nervous reactions. In the early period of adaptation to microgravity records were made of modified spontaneous oculomotor activity (spontaneous vertical nystagmus) and vertical optokinetic nystagmus (VOKN) including alterations in amplitude and VOKN amplification coefficient.

Adaptation, Ocular↗
PubMed2001

A meta-analysis of rape education programs.

Meta-analysis of evaluation studies of rape education programs aimed at college students examined which program characteristics were related to participants' rape-supportive attitude change. Linear regression analyses revealed that: (a) published studies yielded greater attitude change than dissertations, presentations, or unpublished studies; (b) attitude change declined over time; and (c) men in mixed-gender groups experienced less attitude change after interventions than men in single-gender groups. Implications for the development of effective rape education programs are discussed.

Health Education↗
PubMed1988

Linear Ferguson plots of polystyrene sulfate size standards for the quantitative agarose gel electrophoresis of subcellular particles.

Accurately standardized commercial polystyrene sulfate particles in agarose gel electrophoresis yield linear Ferguson plots at pH 7.4 over a gel concentration range up to 0.9% agarose which do not exhibit any significant sigmoidal curve elements, using either a discontinuous buffer system or a continuous buffer. Ferguson plots of these standard-sized particles were evaluated using alternatively a linear or convex model, by means of a newly developed set of programs (to be used in conjunction with program M-LAB) which (i) is sufficiently user-friendly to allow for quantitative agarose gel electrophoresis of subcellular-sized spherical particles based on their convex Ferguson plots with the same operational simplicity previously available for linear Ferguson plots only; (ii) simultaneously and interactively analyzes the Ferguson plots of all particles under consideration on the basis of an extended Ogston model.

Electronic Data Processing↗
PubMed2002

A cognitive approach to child abuse prevention.

This investigation tested the incremental utility of cognitive retraining as a component within a program designed to prevent child maltreatment. High-risk families (N = 96) were randomly assigned to a control condition, home visitation modeled after the Healthy Start program (unenhanced home visitation), or home visitation that included a cognitive component (enhanced home visitation). Mothers were identified late during pregnancy or soon after birth, and their participation continued for 1 year. Lower levels of harsh parenting were found among mothers in the enhanced home visitation condition than among those in the unenhanced home visitation or control conditions. Prevalence of physical abuse (percentage of mothers who were abusive) during the first year was 26% in the control condition, 23% in the unenhanced home visitation condition, and 4% in the enhanced home visitation condition. Benefits were greatest in families that included a medically at-risk child. A linear pattern of benefits was found for child health; as program features were added, benefits for child health increased.

Child↗
PubMed1990

Multiaxis cyclic biomechanical testing of Harrington, Luque, and Drummond implants.

The performance characteristics of Harrington-Moe distraction rods, paired wired Luque rods and Drummond's system were evaluated and compared when subjected to nondestructive cyclic, multidirectional biomechanical testing. Twelve fresh, frozen swine spines with intact facet joints and anterior and posterior ligamentous complexes were instrumented and tested in a specially designed pneumatic testing machine. The instrumented spines were subjected to 207 kN/m2 compression and 49 N-m torsion. Each spine was cycled 28,000 times at 1 cycle per second. Linear and angular displacements were determined by digitizing photographs and video tapes made during testing. A computer program developed and refined for the project was used to complete the data analysis. Approximately 540 items of angular and linear displacement data were collected for each spine. Inspection of the spines after cyclic, multidirectional testing revealed no change in their osteoligamentous integrity compared with pre-testing. Pre- and post-testing radiographs showed no evidence of osseous failure, hook dislodgement or wire breakage. Erosion of laminal bone at the Harrington hook attachment sites was observed. Displacement of the Harrington hooks was seen during off-axis compression-torsion testing. Fretting and deposit of metal wear debris occurred between the sublaminal wires and "L" rods. There was no evidence of loosening of either the Drummond or Luque implants or fatigue failure of any component. Analysis of the linear and angular displacement data showed that the Luque and Drummond instrumented spines displaced less in axial compression, off-axis compression and off-axis compression-torsion than the single Harrington-Moe distraction rod.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Motoneurone task groups: coping with kinematic heterogeneity.

Physiological principles of motor control have generally been based on linear servocontrol theories in which transducers of force, length and velocity are used to provide feedback to the motor actuators. Within the past few years, recordings of the activity of motoneurones and proprioceptors during normal motor behaviour have indicated a diversity that is not consistent with any one theory of motor control. This paper examines the heterogeneity of kinematic conditions under which muscles are called on to perform, and attempts to correlate this with the effects of various fusimotor states on the activity of the muscle spindle afferents, the major sensory signal source in most feedback control schemes. The concept of 'task groups' is proposed, in which functional groups of alpha and gamma motoneurones and spindle afferents are programmed to achieve optimal control over relatively restricted but more linear parts of their operating curves. Such a functional compartmentalization of the motor apparatus is thus consistent with several different theories of servocontrol, although it remains unclear whether such conceptual mechanisms are actually embodied in the highly complex neural circuitry present in the spinal cord and higher motor centres.

Humans↗
PubMed2003

Experimental evaluation of an elastic foundation model to predict contact pressures in knee replacements.

Computational wear prediction is an attractive concept for evaluating new total knee replacement designs prior to physical testing and implementation. An important hurdle to such technology is the lack of in vivo contact pressure predictions. To address this issue, this study evaluates a computationally efficient simulation approach that combines the advantages of rigid and deformable body modeling. The hybrid method uses rigid body dynamics to predict body positions and orientations and elastic foundation theory to predict contact pressures between general three-dimensional surfaces. To evaluate the method, we performed static pressure experiments with a commercial knee implant in neutral alignment using flexion angles of 0, 30, 60, and 90 degrees and loads of 750, 1500, 2250, and 3000N. Using manufacturer CAD geometry for the same implant, an elastic foundation model with linear or nonlinear polyethylene material properties was implemented within a commercial multibody dynamics software program. The model's ability to predict experimental peak and average contact pressures simultaneously was evaluated by performing dynamic simulations to find the static configuration. Both the linear and nonlinear material models predicted the average contact pressure data well, while only the linear material model could simultaneously predict the trends in the peak contact pressure data. This novel modeling approach is sufficiently fast and accurate to be used in design sensitivity and optimization studies of knee implant mechanics and ultimately wear.

Compressive Strength↗
PubMed1999

Opening the black box: using process evaluation measures to assess implementation and theory building.

The past decade has seen increasing recognition in prevention science of the need to move away from a black box approach to intervention evaluation and toward an approach that can elaborate on the mechanisms through which changes in the outcomes operate (Chen & Rossi, 1989; Durlak & Wells, 1997; Spoth et al., 1995). An approach that examines issues of program implementation is particularly critical in the design of efficacy studies of school-based preventive interventions. Numerous preventive intervention strategies are now delivered within the schools, often by regular classroom teachers. The extent to which teachers faithfully deliver a particular curriculum or incorporate instructional strategies emphasized by an intervention is a critical question for the overall project evaluation. This article illustrates the utilization of process measures from a multicomponent school-based prevention program to examine implementation of a teaching staff development intervention, and the program's underlying theoretical basis. Given the nested study design, the analyses utilize hierarchical linear models (Bryk & Raudenbush, 1992) to examine changes in teaching strategies by condition and investigate the hypothesized relationships between teaching practices and student behaviors based on the program's theoretical framework. Results suggest that teaching practices in two of the six intervention focus areas were positively impacted in the first 18 months of the project. Findings also support the relationships between teachers' instructional practices and students' behavior.

Child↗
PubMed1990

IPGMAKER: a program for IBM-compatible personal computers to create and test recipes for immobilized pH gradients.

The program "IPGMAKER" is a computational aid for creating and testing recipes for near-linear immobilized pH gradients. It was written for fast IBM personal computers (with a Type 80386 processor and 80387 coprocessor) and compatibles equipped with a VGA, EGA or Hercules (mono) graphics card. The program is limited to the use of up to 10 acids and/or bases, and to ranges spanning between pH 2 and 12. The resulting recipes are presented either as final concentrations in the 2 chambers of a mixing device for linear gradients or as volumes from 0.2 moles/L stock solutions adjusted to a user-defined average buffering power. One of the subroutines determines the pH, gradient slope and buffering capacity at any location of the gradient and includes a facility to estimate the pI of proteins from the composition of their primary structure.

Acrylamides↗
PubMed2005

The National Program of Cancer Registries: explaining state variations in average cost per case reported.

INTRODUCTION: The Centers for Disease Control and Prevention's National Program of Cancer Registries is a federally funded surveillance program that provides support and assistance to state and territorial health departments for the operation of cancer registries. The objective of this study was to identify factors associated with the Centers for Disease Control and Prevention's costs to report cancer cases during the first 5 years of the National Program of Cancer Registries. METHODS: Information on expenditures and number of cases reported through the National Program of Cancer Registries was used to estimate the average cost per case reported for each state program. Additional information was obtained from other sources, and regression analyses were used to assess the contribution of each factor. RESULTS: Average costs of the National Program of Cancer Registries differed substantially among programs and were inversely associated with the number of cases reported (P < .001). The geographic area of the state was positively associated with the cost (P = .01), as was the regional cost of living (P = .08), whereas the program type (i.e., enhancement or planning) was inversely associated with cost (P = .08). CONCLUSION: The apparent existence of economies of scale suggests that contiguous state programs might benefit from sharing infrastructure and other fixed costs, such as database management resources, depending on the geographic area and population size served. Sharing database management resources might also promote uniform data collection and quality control practices, reduce the information-sharing burden among states, and allow more resources to be used for other cancer prevention and control activities.

Centers for Disease Control and Prevention, U.S.↗
PubMed1995

Evaluation of a community-based youth violence prevention project.

PURPOSE: To investigate the association of exposure to a community-based youth violence prevention project with adolescents' knowledge and attitudes about violence. METHODS: Two samples of 400 teens each from Boston neighborhoods were surveyed by random-digit dialed telephone techniques: one at the start of the project and one after 1 year of implementation. Regression analyses were used to investigate associations between exposure to different educational formats and outcome measures. RESULTS: Only self-reported exposure to the mass media campaign was significantly associated with higher scores in both knowledge and attitudes. An independent interaction between gender and exposure to the mass media campaign was found among males. Analyses using a historic control group support a program effect and not recall bias. Exposure to workshops or one-on-one discussions about violence prevention were not significantly associated with outcome scores. CONCLUSION: The measurable effect of the mass media may be somewhat related to the strength of that stimulus over the study period and suggests that 12 months is too short a time frame for evaluating community-based educational efforts.

Adolescent↗
PubMed1988

Conceptual age and ultrasound measurements of gestational sac and crown-rump length in in vitro fertilization pregnancies.

The growth of the mean gestational sac diameter and the crown-rump length were evaluated from individual series and found to be linear in singletons, twins, and triplets from an in vitro fertilization program as well as in pregnancies with ovulation determined from serial ultrasound folliculograms. No difference in growth rate between the different groups was observed. The 95% confidence limits were 7.7 days before and 7.5 days after mean for the gestational sac diameter, and 5.2 days before and 5.6 days after mean for the crown-rump length. These limits, used together with new linear equations, create less anxiety and less unnecessary surgical intervention than current nonlinear standards when conceptual age is known and the gestational sac or the crown-rump length are too small to be measured.

Embryonic and Fetal Development↗
PubMed1982

A comparative study of carrier detection in haemophilia A by linear discriminant function.

Blood samples collected from 37 definite carriers, 31 normal women and 64 possible carriers were examined for factor VIII-related activities. Five variables: factor VIII coagulant activity (VIII:C) (X1), factor VIII-related antigen (VIIIR:Ag) (X2), ristocetin co-factor (VIIIR:RC) (X3), ratio of VIIIR:Ag to VIII:C (A/C) (X4) and ratio of VIII:RC to VIII:C (R/C) (X5), and 28 combinations of one to five variables were used to derive 28 linear discriminant functions. The calculation of discriminant function coefficient, individual discriminant score and cut-off point, and the identification of normals or carriers were processed by the computer package of a biomedical computer program used at University of California at Los Angeles. A comparison of 28 linear discriminant functions for carrier detection in haemophilia A has indicated that the best and simplest is y = 0.11668X1 (VIII:C)--0.06042X2 (VIIIR:Ag), (cut-off point y = 2.03742). It identified 94.6% of carriers without a single misclassification in the normal group, and the overall identification rate was 97.1%. Of 29 daughters of definite carriers who had no haemophilic sons, 13, or 44.8%, could be identified as carriers. It was found that VIII:RC was not as good as VIIIR:Ag for carrier detection; however, it may be concluded from this study that VIIIR:RC can be used as a supplement, if not a substitute, for VIII:Ag in the carrier detection of haemophilia A.

Adolescent↗
PubMed2003

Views of practicing dentists regarding a mandatory fifth year of training.

As part of a U.S. Health Resources and Services Administration-funded evaluation of the impact of federal funding on postgraduate general dentistry programs, a random sample of 6,725 dentists graduating in 1989, 1993, and 1997 were surveyed regarding practice patterns, advanced training, populations served, services provided, and their position on a mandatory fifth year of training. Responses (1,965) showed 48 percent supporting a mandatory year and 52 percent not supportive. Open-ended comments were provided by 1,626 respondents. The main reasons for supporting a mandatory fifth year were the need for more instructional time and need for a transition year. Individual choice, no value in a fifth year of dental school, mentoring available elsewhere, and cost were cited in opposition. The following respondents were significantly more likely than other respondents to support a mandatory fifth year: individuals who had completed an AEGD, GPR, or specialty program; were Asian; held salaried positions in a community clinic, nursing home, or hospital; or described themselves as a consultant. Graduates in 1993 and 1997 were less supportive of a mandatory fifth year than were 1989 graduates. Significant differences in the reasons offered in support of respondents' positions on the issue were observed among AEGD, GPR, specialists, and nonspecialists and the three cohort years.

Attitude of Health Personnel↗
PubMed1997

Lone parent families are an independent risk factor for lower rates of childhood immunisation in London.

The aim of this study was to determine associations between indicators of social deprivation and the uptake of primary immunisation in London. Correlation coefficients were calculated between immunisation coverage in London for each of the 28 inner and outer London district health authorities in November 1991 and a range of possible explanatory variables from small area statistics data from the November 1991 census. The proportions of children under 5 years of age, lone parent families, unemployed members of the workforce, domestic overcrowding, ethnic minorities, and unskilled workforce were correlated significantly with the coverage of primary immunisation for third dose diphtheria (D3) and pertussis (P3) at 12 months. A significant correlation with measles, mumps, and rubella (MMR) at 24 months existed only for lone parent families. Multiple linear regression weighted by population size was used to identify independent predictors of variation in immunisation cover. The proportion of lone parent families in each district health authority was the only significant independent risk factor consistently associated with variation in immunisation coverage for D3, P3, and MMR. The proportion of lone parent families explained 42% of the variation in coverage for D3 in November 1991. This study has identified lone parenthood as an important independent risk factor in London for failure to complete immunisation.

Adult↗