Showing papers by "University of Queensland published in 1996"

Inefficient muscular stabilization of the lumbar spine associated with low back pain : A motor control evaluation of transversus abdominis

Abstract: Study Design. The contribution of transversus abdominis to spinal stabilization was evaluated indirectly in people with and without low back pain using an experimental model identifying the coordination of trunk muscles in response to a disturbance to the spine produced by arm movement.

Group Norms and the Attitude-Behavior Relationship: A Role for Group Identification.

Abstract: Two studies provided support for the proposal that the role of norms in attitude-behavior relations can be usefully reconceptualized from the perspective of social identity/self-categorization theory. The first study revealed that the perceived norms of a behaviorally relevant reference group influenced intentions to engage in regular exercise, but only for subjects who identified strongly with the group, whereas the effect of perceived behavioral control (a personal factor) was strongest for low identifiers. Similarly, Study 2 revealed that the effect of group norms on females' intentions to engage in sun-protective behavior was evident only for high identifiers and that the effects of one of the personal variables (attitude) was stronger for low than for high identifiers. Additional results revealed that the perceived group norm predicted subjects' attitude, as did the perceived consequences of performing the behavior. The latter result was evident only for low identifiers.

Multifidus muscle recovery is not automatic after resolution of acute, first-episode low back pain.

Abstract: Study Design. A clinical study was conducted on 39 patients with acute, first-episode, unilateral low back pain and unilateral, segmental inhibition of the multifidus muscle. Patients were allocated randomly to a control or treatment group. Objectives. To document the natural course of lumbar multifidus recovery and to evaluate the effectiveness of specific, localized, exercise therapy on muscle recovery. Summary of Background Data. Acute low back pain usually resolves spontaneously, but the recurrence rate is high. Inhibition of multifidus occurs with acute, first-episode, low back pain, and pathologic changes in this muscle have been linked with poor outcome and recurrence of symptoms. Methods. Patients in group 1 received medical treatment only. Patients in group 2 received medical treatment and specific, localized, exercise therapy. Outcome measures for both groups included 4 weekly assessments of pain, disability, range of motion, and size of the multifidus cross-sectional area. Independent examiners were blinded to group allocation. Patients were reassessed at a 10-week follow-up examination. Results. Multifidus muscle recovery was not spontaneous on remission of painful symptoms in patients in group 1. Muscle recovery was more rapid and more complete in patients in group 2 who received exercise therapy (P = 0.0001). Other outcome measurements were similar for the two groups at the 4-week examination. Although they resumed normal levels of activity, patients in group 1 still had decreased multifidus muscle size at the 10-week follow-up examination. Conclusions. Multifidus muscle recovery is not spontaneous on remission of painful symptoms. Lack of localized, muscle support may be one reason for the high recurrence rate of low back pain following the initial episode.

Childhood-onset versus adolescent-onset antisocial conduct problems in males: Natural history from ages 3 to 18 years

Abstract: We report data that support the distinction between childhood-onset and adolescent-onset type conduct problems. Natural histories are described from a representative birth cohort of 457 males studied longitudinally from age 3 to 18 years. Childhood- and adolescent-onset cases differed on temperament as early as age 3 years, but almost half of childhood-onset cases did not become seriously delinquent. Type comparisons were consistent with our contention that males whose antisocial behavior follows a life-course-persistent path differ from males who follow an adolescence-limited path. As adolescents, the two types differed on convictions for violent crime, personality profiles, school leaving, and bonds to family. These differences can be attributed to developmental history because the two groups were well matched on measures of antisocial conduct at age 18 years: parent-reports, self-reports, and adjudication records. By age 18 years, many conduct-problem boys had encountered factors that could ensnare them in an antisocial future: substance dependence, unsafe sex, dangerous driving habits, delinquent friends, delinquent perceptions, and unemployment. Implications for theory, research design, prevention, and therapeutic treatment of conduct problems are highlighted.

A comparison of computer-based methods for the determination of onset of muscle contraction using electromyography

Abstract: Little consensus exists in the literature regarding methods for determination of the onset of electromyographic (EMG) activity. The aim of this study was to compare the relative accuracy of a range of computer-based techniques with respect to EMG onset determined visually by an experienced examiner. Twenty-seven methods were compared which varied in terms of EMG processing (low pass filtering at 10, 50 and 500 Hz), threshold value (1, 2 and 3 SD beyond mean of baseline activity) and the number of samples for which the mean must exceed the defined threshold (20, 50 and 100 ms). Three hundred randomly selected trials of a postural task were evaluated using each technique. The visual determination of EMG onset was found to be highly repeatable between days. Linear regression equations were calculated for the values selected by each computer method which indicated that the onset values selected by the majority of the parameter combinations deviated significantly from the visually derived onset values. Several methods accurately selected the time of onset of EMG activity and are recommended for future use.

Randomized Quantile Residuals

Abstract: In this article we give a general definition of residuals for regression models with independent responses Our definition produces residuals that are exactly normal, apart from sampling variability in the estimated parameters, by inverting the fitted distribution function for each response value and finding the equivalent standard normal quantile Our definition includes some randomization to achieve continuous residuals when the response variable is discrete Quantile residuals are easily computed in computer packages such as SAS, S-Plus, GLIM, or LispStat, and allow residual analyses to be carried out in many commonly occurring situations in which the customary definitions of residuals fail Quantile residuals are applied in this article to three example data sets

Endotoxin signal transduction in macrophages

Abstract: Through its action on macrophages, bacterial lipopolysaccharide (LPS) or endotoxin can trigger responses that are protective or injurious to the host. This review examines the effects of LPS on macrophages by following events from the cell surface to the nucleus. The involvement of protein tyrosine kinases, mitogen-activated protein kinases, protein kinase C, G proteins, protein kinase A, ceramide-activated protein kinase, and microtubules in this process are reviewed. At the nuclear level, rel, C/EBP, Ets, Egr, fos, and jun family members have been implicated in activation of LPS-inducible gene expression.

Family enhancement of cognitive style in anxious and aggressive children.

Abstract: Previous research has shown that anxious adults provide more threat interpretations of ambiguous stimuli than other clinic and nonclinic persons. We were interested in investigating if the same bias occurs in anxious children and how family processes impact on these children's interpretations of ambiguity. Anxious, oppositional, and nonclinical children and their parents were asked separately to interpret and provide plans of action to ambiguous scenarios. Afterwards, Each family was asked to discuss two of these situations as a family and for the child to provide a final response. The results showed that anxious and oppositional children were both more likely to interpret ambiguous scenarios in a threatening manner. However, the two clinic groups differed in that the anxious children predominantly chose avoidant solutions whereas the oppositional children chose aggressive solutions. After family discussions, both the anxious children's avoidant plans of action and the oppositional children's aggressive plans increased. Thus, this study provides the first evidence of family enhancement of avoidant and aggressive responses in children. These results support a model of anxiety that emphasizes the development of an anxious cognitive style in the context of anxiety-supporting family processes.

A male-specific role for SOX9 in vertebrate sex determination

Abstract: Mutation analyses of patients with campomelic dysplasia, a bone dysmorphology and XY sex reversal syndrome, indicate that the SRY-related gene SOX9 is involved in both skeletal development and sex determination. To clarify the role SOX9 plays in vertebrate sex determination, we have investigated its expression during gonad development in mouse and chicken embryos. In the mouse, high levels of Sox9 mRNA were found in male (XY) but not female (XX) genital ridges, and were localised to the sex cords of the developing testis. Purified fetal germ cells lacked Sox9 expression, indicating that Sox9 expression is specific to the Sertoli cell lineage. Sex specificity of SOX9 protein expression was confirmed using a polyclonal antiserum. The timing and cell-type specificity of Sox9 expression suggests that Sox9 may be directly regulated by SRY. Male-specific expression of cSOX9 mRNA during the sex determination period was also observed in chicken genital ridges. The conservation of sexually dimorphic expression in two vertebrate classes which have significant differences in their sex determination mechanisms, points to a fundamental role for SOX9 in testis determination in vertebrates. Sox9 expression was maintained in the mouse testis during fetal and adult life, but no expression was seen at any stage by in situ hybridisation in the developing ovary. Male-specific expression was also observed in the cells surrounding the Mullerian ducts and in the epididymis, and expression in both sexes was detected in the developing collecting ducts of the metanephric kidney. These results suggest that SOX9 may have a wider role in the development of the genitourinary system.

Carbon Dioxide Reforming of Methane To Produce Synthesis Gas over Metal-Supported Catalysts: State of the Art

Abstract: Carbon dioxide reforming of methane produces synthesis gas with a low hydrogen to carbon monoxide ratio, which is desirable for many industrial synthesis processes. This reaction also has very important environmental implications since both methane and carbon dioxide contribute to the greenhouse effect. Converting these gases into a valuable feedstock may significantly reduce the atmospheric emissions of CO2 and CH4. In this paper, we present a comprehensive review on the thermodynamics, catalyst selection and activity, reaction mechanism, and kinetics of this important reaction. Recently, research has centered on the development of catalysts and the feasible applications of this reaction in industry. Group VIII metals supported on oxides are found to be effective for this reason. However, carbon deposition causing catalyst deactivation is the major problem inhibiting the industrial application of the CO2/CH4 reaction. Ni-based catalysts impregnated on certain supports show carbon-free operation and thus attract much attention. To develop an effective catalyst for CO2 reforming of CH4 and accelerate the commercial application of the reaction, the following are identified to be the most important areas for future work: (1) selection of metal and support and studying the effect of their interaction on catalyst activity; (2) the effect of different promoter on catalyst activity; (3) the reaction mechanism and kinetics; and (4) pilot reactor performance and scale-up operation.

Identification of factors which influence the technical inefficiency of indian farmers

Abstract: The agricultural production of Indian farmers is investigated using a stochastic frontier production function which incorporates a model for the technical inefficiency effects. Farm-level data from the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) are used. Variables considered in the model for the inefficiency effects include the age and level of education of the farmers, farm size and the year of observation. The parameters of the stochastic frontier production function are estimated simultaneously with those involved in the model for the inefficiency effects. This approach differs from the usual practice of predicting farm-level inefficiency effects and then regressing these upon various factors in a second-stage of modelling. The results indicate that the above factors do have a significant influence upon the inefficiency effects of farmers in two of the three villages considered.

Macrophages ingest and are activated by bacterial DNA.

Abstract: Recent evidence suggests that bacterial DNA activates immune responses Here we showed that TNF-alpha mRNA was induced in bone marrow-derived macrophages and the macrophage cell line RAW 264 by plasmid DNA, but not by DNaseI-digested plasmid, plasmid methylated on CpG dinucleotides, or by vertebrate genomic DNA, which is naturally largely methylated on these sequences Synthetic polynucleotides poly d(I-C) and poly I x poly C also induced TNF-alpha IL-1 beta and plasminogen activator inhibitor-2 mRNAs were induced by plasmid DNA, and IFN-gamma-pretreated macrophages responded to DNA with induction of inducible nitric oxide synthase The HIV-1 long terminal repeat was activated by exogenous DNA in a manner similar to TNF-alpha, and was also activated by a CpG-containing oligonucleotide Transcription factor nuclear factor-kappa B (NF-kappa B) is involved in regulation of the HIV-1 long terminal repeat and many inflammatory response genes NF-kappa B binding activity was increased by plasmid DNA An important question is whether these effects involve DNA binding to a cell surface receptor that signals to the interior, or whether internalization is necessary Here we found that plasmid was taken up by RAW 264 cells and remained sufficiently intact to code for luciferase protein Results suggest that DNA is taken up by macrophages and characteristic bacterial DNA sequences, which include an unmethylated CpG sequence, activate a signaling cascade leading to activation of NF-kappa B and inflammatory gene induction Relevance to DNA vaccination, gene therapy, antisense, and transfection studies is discussed

Carbon dioxide reforming of methane to produce synthesis gas over metal-supported catalysts: State of the art

Abstract: Carbon dioxide reforming of methane produces synthesis gas with a low hydrogen to carbon monoxide ratio, which is desirable for many industrial synthesis processes. This reaction also has very important environmental implications since both methane and carbon dioxide contribute to the greenhouse effect. Converting these gases into a valuable feedstock may significantly reduce the atmospheric emissions of CO2 and CH4. In this paper, we present a comprehensive review on the thermodynamics, catalyst selection and activity, reaction mechanism, and kinetics of this important reaction. Recently, research has centered on the development of catalysts and the feasible applications of this reaction in industry. Group VIII metals supported on oxides are found to be effective for this reason. However, carbon deposition causing catalyst deactivation is the major problem inhibiting the industrial application of the CO2/CH4 reaction. Ni-based catalysts impregnated on certain supports show carbon-free operation and thus attract much attention. To develop an effective catalyst for CO2 reforming of CH4 and accelerate the commercial application of the reaction, the following are identified to be the most important areas for future work: (1) selection of metal and support and studying the effect of their interaction on catalyst activity; (2) the effect of different promoter on catalyst activity; (3) the reaction mechanism and kinetics; and (4) pilot reactor performance and scale-up operation.

Advances in Mesoporous Molecular Sieve MCM-41

Abstract: The discovery of mesoporous molecular sieves, MCM-41, which possesses a regular hexagonal array of uniform pore openings, aroused a worldwide resurgence in this field. This is not only because it has brought about a series of novel mesoporous materials with various compositions which may find applications in catalysis, adsorption, and guest-host chemistry, but also it has opened a new avenue for creating zeotype materials. This paper presents a comprehensive overview of recent advances in the field of MCM-41. Beginning with the chemistry of surfactant/silicate solutions, progresses made in design and synthesis, characterization, and physicochemical property evaluation of MCM-41 are enumerated. Proposed formation mechanisms are presented, discussed, and identified. Potential applications are reviewed and projected. More than 100 references are cited.

Optical angular-momentum transfer to trapped absorbing particles

Abstract: Spin angular momentum of photons and the associated polarization of light has been known for many years. However, it is only over the last decade or so that physically realizable laboratory light beams have been used to study the orbital angular momentum of light. In many respects, orbital and spin angular momentum behave in a similar manner, but they differ significantly in others. In particular, orbital angular momentum offers exciting new possibilities with respect to the optical manipulation of matter and to the study of the entanglement of photons.Bringing together 44 landmark papers, "Optical Angular Momentum" offers the first comprehensive overview of the subject as it has developed. It chronicles the first decade of this important subject and gives a definitive statement of the current status of all aspects of optical angular momentum. In each chapter, the editors include a concise introduction, putting the selected papers into context and outlining the key articles a

An Electrochemical Model for Prediction of Corrosion of Mild Steel in Aqueous Carbon Dioxide Solutions

Abstract: A predictive model was developed for uniform carbon dioxide (CO2) corrosion, based on modeling of individual electrochemical reactions in a water-CO2 system. The model takes into account the electrochemical reactions of hydrogen ion (H+) reduction, carbonic acid (H2CO3) reduction, direct water reduction, oxygen reduction, and anodic dissolution of iron. The required electrochemical parameters (e.g., exchange current densities and Tafel slopes) for different reactions were determined from experiments conducted in glass cells. The corrosion process was monitored using polarization resistance, potentiodynamic sweep, electrochemical impedance, and weight-loss measurements. The model was calibrated for two mild steels over a range of parameters: temperature (t) = 20°C to 80°C, pH = 3 to 6, partial pressure of CO2 (PCO2) = 0 bar to 1 bar (0 kPa to 100 kPa), and ω = 0 rpm to 5,000 rpm (vp = 0 m/s to 2.5 m/s). The model was applicable for uniform corrosion with no protective films present. Performance of...

Research Commentary: Rethinking “Diversity” in Information Systems Research

Abstract: Three types of diversity have been prominent in the Information Systems discipline for over a decade: a diversity in the problems addressed; b diversity in the theoretical foundations and reference disciplines used to account for IS phenomena; and c diversity in the methods used to collect, analyze, and interpret data. History has played a major part in encouraging IS researchers to use diversity as a means of countering criticisms of their discipline and increasing their research rigor and productivity. In particular, frequent recourse to reference disciplines has underpinned much of the research that has been undertaken since the early 1980s. There are now signs, however, that the level of diversity that currently exists in IS research may be problematic. In this paper, we consider some of the benefits and costs of allowing diversity to reign in the IS discipline. We also propose a structure that we hope will facilitate discourse on the benefits and costs of diversity and on the role that diversity should now play in the IS discipline.

A model conforming the decline in follicle numbers to the age of menopause in women

Abstract: The store of primordial follicles in the ovary is fixed before birth and dwindles with age until it is unable to provide enough Graafian stages to sustain menstrual cyclicity. According to a simple bi-exponential model of ageing, the rate of follicle disappearance increases at age 37.5 years (or when 25 000 follicles remain) so that the numbers fall to approximately 1000 at 51 years, the median age of menopause in the population. This study attempts to produce a biologically more realistic model of follicle disappearance and harmonizes follicle dynamics with the distribution of menopausal ages from an American survey. The step-change in the rate of follicle attrition was replaced by a model which assumed that this rate changes more gradually with the size of the follicle store. This produced a distribution of predicted menopausal ages (based on an assumed threshold of 1000 follicles) which was closer to observed data. The fit further improved when the model was modified by having a threshold that varied across the population. Using such a stochastic threshold model for menopause, the number of fertile years remaining could be forecast with an acceptable margin of uncertainty if it ever becomes possible to estimate the size of the follicle store in vivo.

Targeted disruption of the Wnt2 gene results in placentation defects

Abstract: Wnt genes have been implicated in a range of developmental processes in the mouse including the patterning of the central nervous system and limbs. Reported here for the first time is the expression of Wnt2 in the early heart field of 7.5-8.5 dpc (days post-coitum) mouse embryos, making Wnt2 a potentially useful gene marker for the early stages of heart development. Expression was also detected in the allantois from 8.0 dpc and at later stages in the placenta and umbilicus. Mice deficient in Wnt2, generated by gene targeting, displayed runting and approximately 50% died perinatally. Histological analysis revealed alterations in the size and structure of placentas from these mice from 14.5 dpc. The placental defects were associated primarily with the labyrinthine zone and included oedema and tissue disruption and accumulation of maternal blood in large pools. There was also an apparent decrease in the number of foetal capillaries and an increase in the amount of fibrinoid material in the Wnt2 mutant placentas. These results suggest that Wnt2 is required for the proper vascularisation of the mouse placenta and the placental defects in Wnt2-deficient mice result in a reduction in birthweight and perinatal lethality.

Enzymatic pathway for the bacterial degradation of the cyanobacterial cyclic peptide toxin microcystin LR.

Abstract: An isolated bacterium, identified as a new Sphingomonas species, was demonstrated to contain a novel enzymatic pathway which acted on microcystin LR, the most common cyanobacterial cyclic peptide toxin. Degradation of microcystin LR was mediated by at least three intracellular hydrolytic enzymes. The use of classic protease inhibitors allowed (i) the classification of these enzymes into general protease families and (ii) the in vitro accumulation of otherwise transient microcystin LR degradation products. The initial site of hydrolytic cleavage of the parent cyclic peptide by an enzyme that we designate microcystinase is at the 3-amino-9-methoxy-2,6,8-trimethyl-10-phenyl-deca-4,6-dienoic acid (Adda)-Arg peptide bond. Two intermediates of microcystin LR enzymatic degradation have been identified; one is linearized (acyclo-) microcystin LR, NH2-Adda-Glu(iso)-methyldehydroalanine-Ala-Leu-beta-methylas partate-Arg-OH, and the other is the tetrapeptide NH2-Adda-Glu(iso)-methyldehydroalanine-Ala-OH. The intermediate degradation products were less active than the parent cyclic peptide; the observed 50% inhibitory concentrations for crude chicken brain protein phosphatase were 0.6 nM for microcystin LR, 95 nM for linear LR, and 12 nM for the tetrapeptide. These linear peptides were nontoxic to mice at doses up to 250 micrograms/kg. Ring opening of the potent hepatotoxin microcystin LR by bacterial microcystinase effectively renders the compound nontoxic by dramatically reducing the interaction with the target protein phosphatase.

The initial effects of a cervical spine manipulative physiotherapy treatment on the pain and dysfunction of lateral epicondylalgia

Abstract: Manipulative therapy is frequently used in the management of musculoskeletal pain. A frequently reported clinical feature of this treatment is the immediacy with which it appears to initiate improvement in pain and function. A randomised, double blind, placebo controlled, repeated measures design was employed to study the initial effects of a cervical spine treatment technique in a group of 15 patients with lateral epicondylalgia. Pressure pain threshold, pain-free grip strength, upper limb neurodynamics, pain and function were assessed prior to and following application of either a treatment, placebo or control condition. All subjects received all three conditions. Differences between the pre-post measures were used as indicators of change in subject's symptom profiles. The treatment condition produced significant improvement in pressure pain threshold, pain-free grip strength, neurodynamics and pain scores relative to placebo and control conditions (P < 0.05). In summary, this study demonstrates that manipulative therapy is capable of eliciting a rapid hypoalgesic effect.

Self-awareness of deficits in adults with traumatic brain injury : how best to measure ?

Abstract: Some method of assessing self-awareness of deficits in patients with traumatic brain injury (TBI) is required to increase our understanding of the phenomenon, and to then evaluate strategies for clinical intervention with patients who lack such self-awareness. Options for the assessment of self-awareness of deficits following TBI are reviewed. The most commonly used method is comparison of patients' self-ratings on questionnaires of functional abilities with ratings by relatives or staff on the same questionnaires. An additional method of assessment, an interviewer-rated semi-structured interview is proposed (the Self-Awareness of Deficits Interview), and some preliminary inter-rater reliability data are presented. However, quantitative methods of evaluating self-awareness have shortcomings, and qualitative research may be more appropriate in some circumstances. An approach which makes use of multiple measures to evaluate self-awareness of deficits is recommended.