Behavior and interactions of children in cooperative groups in lower and middle elementary grades

The study investigated the behaviors and interactions of children in structured and unstructured groups as they worked together on a 6-week social studies activity each term for 3 school terms. Two hundred and twelve children in Grade 1 and 184 children in Grade 3 participated in the study. Stratified random assignment occurred so that each gender-balanced group consisted of 1 high-, 2 medium-, and 1 low-ability student. The results show that the children in the structured groups were consistently more cooperative and they provided more elaborated and nonelaborated help than did their peers in the unstructured groups. The children in the structured groups in Grade 3 obtained higher reading and learning outcome scores than their peers in the unstructured groups.

The role of parental anxiety in the treatment of childhood anxiety

Sixty-seven children aged 7 to 14 who met diagnostic criteria for an anxiety disorder were assigned to conditions according to parental anxiety level. Within these conditions, children were randomly assigned to I of 2 treatments: child-focused cognitive-behavioral therapy (CBT) or child-focused CBT plus parental anxiety management (CBT + PAM). At posttreatment, results indicated that within the child-anxiety-only condition, 82% of the children in the CBT condition no longer met criteria for an anxiety disorder compared with 80% in the CBT + PAM condition. Within the child + parental anxiety condition, 39% in the CBT condition no longer met criteria compared with 77% in the CBT + PAM condition. At follow-up, these differences were maintained, with some weakening over time. Results were not consistent across outcome measures. The interpretation and potential clinical implications of these findings are discussed.

A mathematical model for estimating the extent of solute- and water-flux heterogeneity in multiple sample percolation experiments

Multiple sampling is widely used in vadose zone percolation experiments to investigate the extent in which soil structure heterogeneities influence the spatial and temporal distributions of water and solutes. In this note, a simple, robust, mathematical model, based on the beta-statistical distribution, is proposed as a method of quantifying the magnitude of heterogeneity in such experiments. The model relies on fitting two parameters, alpha and zeta to the cumulative elution curves generated in multiple-sample percolation experiments. The model does not require knowledge of the soil structure. A homogeneous or uniform distribution of a solute and/or soil-water is indicated by alpha = zeta = 1, Using these parameters, a heterogeneity index (HI) is defined as root 3 times the ratio of the standard deviation and mean. Uniform or homogeneous flow of water or solutes is indicated by HI = 1 and heterogeneity is indicated by HI > 1. A large value for this index may indicate preferential flow. The heterogeneity index relies only on knowledge of the elution curves generated from multiple sample percolation experiments and is, therefore, easily calculated. The index may also be used to describe and compare the differences in solute and soil-water percolation from different experiments. The use of this index is discussed for several different leaching experiments. (C) 1999 Elsevier Science B.V. All rights reserved.

Autoinhibition by an internal nuclear localization signal revealed by the crystal structure of mammalian importin alpha

Importin alpha is the nuclear import receptor that recognizes classical monopartite and bipartite nuclear localization signals (NLSs). The structure of mouse importin alpha has been determined at 2.5 Angstrom resolution. The structure shows a large C-terminal domain containing armadillo repeats, and a less structured N-terminal importin beta-binding domain containing an internal NLS bound to the NLS-binding site. The structure explains the regulatory switch between the cytoplasmic, high-affinity form, and the nuclear, low-affinity form for NLS binding of the nuclear import receptor predicted by the current models of nuclear import. Importin beta conceivably converts the low- to high-affinity form by binding to a site overlapping the autoinhibitory sequence. The structure also has implications for understanding NLS recognition, and the structures of armadillo and HEAT repeats.

Anxious children and their parents: What do they expect?

Assigned 73 children, ages 7 to 14, to 1 of 3 groups (anxious, clinical control, and nonclinical control) according to their diagnostic status. Within the anxious group, children were assigned to 1 of 2 further groups on the basis of self-reported parental anxiety-either the child anxiety only group or the child + parent anxiety group. All children completed an experimental task (giving a brief talk in front of a video camera), which was the focus for a series of structured family discussions between the child and his or her parents. The aims of the study were to measure and compare across groups (a) the evaluations of children and their parents regarding the child's predicted anxiety and skill level and (b) the effect of the family discussion on children's expectations. Results indicated that, prior to the family discussion, anxious children's expectations of their future performance did not differ from those of control children. Similarly, there were no differences in children's expectations between the child anxiety group and the child + parent anxiety group. Second, compared to mothers in the child anxiety group, mothers in the child + parent anxiety group expected that their children would be more anxious and more likely to choose an avoidant problem solution (but not less skilled). Finally, the family discussion was found to produce no changes in anxious children's expectations of their future performance. The implications of these findings are discussed.

Accuracy of predicting a child's response to potential threat: A comparison of children and their mothers

Considerable research has indicated that children and their parents often demonstrate marked discrepancies in their reporting of anxiety-related phenomena. In such cases, the question arises as to whether children are capable of accurately reporting on their anxiety. In the present study, 50 children (aged 5 to 14 years) were asked to approach a large, German Shepherd dog. Prior to the task, both the mother and child independently predicted the closest point likely to be reached by the child and the degree of anxiety likely to be experienced. These predictions were then compared with the actual phenomena displayed by the child during the task. On the behavioural measure (closest step reached), both the child and mother demonstrated equivalent predictive accuracy. On the subjective measure (fear ratings) children were considerably more accurate than their mothers. The data were not influenced by gender, age, or clinical status. The results indicate the ability of children to accurately predict their anxious responses, and support the value of incorporating children's self-reports in the assessment of emotional disorders.

Differentiation of soil properties related to the spatial association of wheat roots and soil macropores

Under certain soil conditions, e.g. hardsetting clay B-horizons of South-Eastern Australia, wheat plants do not perform as well as would be expected given measurements of bulk soil attributes. In such soils, measurement indicates that a large proportion (80%) of roots are preferentially located in the soil within 1 mm of macropores. This paper addresses the question of whether there are biological and soil chemical effects concomitant with this observed spatial relationship. The properties of soil manually dissected from the 1-3 mm wide region surrounding macropores, the macropore sheath, were compared to those that are measured in a conventional manner on the bulk soil. Field specimens of two different soil materials were dissected to examine biological differentiation. To ascertain whether the macropore sheath soil differs from rhizosphere soil, wheat was grown in structured and repacked cores under laboratory conditions. The macropore sheath soil contained more microbial biomass per unit mass than both the bulk soil and the rhizosphere. The bacterial population in the macropore sheath was able to utilise a wider range of carbon substrates and to a greater extent than the bacterial population in the corresponding bulk soil. These differences between the macropore sheath and bulk soil were almost non-existent in the repacked cores. Evidence for larger numbers of propagules of the broad host range fungus Pythium in the macropore sheath soil were also obtained.

Quantifying the influence of intra-aggregate concentration gradients on solute transport

The physical nonequilibrium of solute concentration resulting from preferential now of soil water has often led to models where the soil is partitioned into two regions: preferential flow paths, where solute transport occurs mainly by advection, and the remaining region, where significant solute transport occurs through diffusive exchange with the flow paths. These two-region models commonly ignore concentration gradients within the regions. Our objective was to develop a simple model to assess the influence of concentration gradients on solute transport and to compare model results with experiments conducted on structured materials. The model calculates the distribution of solutes in a single spherical aggregate surrounded by preferential now paths and subjected to alternating boundary conditions representing either an exchange of solutes between the two regions (a wet period) or no exchange but redistribution of solutes within the aggregate (a dry period). The key parameter in the model is the aggregate radius, which defines the diffusive time scales. We conducted intermittent leaching experiments on a column of packed porous spheres and on a large (300 mm long by 216 mm diameter) undisturbed field soil core to test the validity of the model and its application to field soils. Alternating wet and dry periods enhanced leaching by up to 20% for this soil, which was consistent with the model's prediction, given a fitted equivalent aggregate radius of 1.8 cm, If similar results are obtained for other soils, use of alternating wet and dry periods could improve management of solutes, for example in salinity control and in soil remediation.

Effect of smoke-free policies on the behaviour of social smokers

Objective-To test the hypothesis that proposed amendments to the Occupational Safety and Health Act making all enclosed workplaces in Western Australia smoke free would result in a decrease in cigarette consumption by patrons at nightclubs, pubs, and restaurants without adversely affecting attendance. Design-Cross sectional structured interview survey. Participants and setting-Patrons of several inner city pubs and nightclubs in Perth were interviewed while queuing for admission to these venues. Outcome measures-Current social habits, smoking habits, and how these might be affected by the proposed regulations. Persons who did not smoke daily were classified as social smokers. Results-Half (50%) of the 374 patrons interviewed were male, 51% currently did not smoke at all, 34.3% smoked every day, and the remaining 15.7% smoked, brat not every day. A clear majority (62.5%) of all 374 respondents anticipated no change to the frequency of their patronage of hospitality venues if smoke-free policies became mandatory One in five (19.3%) indicated that they would,ao out more often, and 18.2% said they would go out less often. Half (52%) of daily smokers anticipated no change to their cigarette consumption, while 44.5% of daily smokers anticipated a reduction in consumption. A majority of social smokers (54%) predicted a reduction in their cigarette consumption, with 42% of these anticipating quitting. Conclusions-One in nine (11.5%) of smokers say that adoption of smoke-Pi ee policies would prompt them to quit smoking entirely without a significant decrease in attendance at pubs and nightclubs. There can be few other initiatives as simple, cheap, and popular that would achieve so much for public health.

Conformational selection of inhibitors and substrates by proteolytic enzymes: Implications for drug design and polypeptide processing

Inhibitors of proteolytic enzymes (proteases) are emerging as prospective treatments for diseases such as AIDS and viral infections, cancers, inflammatory disorders, and Alzheimer's disease. Generic approaches to the design of protease inhibitors are limited by the unpredictability of interactions between, and structural changes to, inhibitor and protease during binding. A computer analysis of superimposed crystal structures for 266 small molecule inhibitors bound to 48 proteases (16 aspartic, 17 serine, 8 cysteine, and 7 metallo) provides the first conclusive proof that inhibitors, including substrate analogues, commonly bind in an extended beta-strand conformation at the active sites of all these proteases. Representative superimposed structures are shown for (a) multiple inhibitors bound to a protease of each class, (b) single inhibitors each bound to multiple proteases, and (c) conformationally constrained inhibitors bound to proteases. Thus inhibitor/substrate conformation, rather than sequence/composition alone, influences protease recognition, and this has profound implications for inhibitor design. This conclusion is supported by NMR, CD, and binding studies for HIV-1 protease inhibitors/ substrates which, when preorganized in an extended conformation, have significantly higher protease affinity. Recognition is dependent upon conformational equilibria since helical and turn peptide conformations are not processed by proteases. Conformational selection explains the resistance of folded/structured regions of proteins to proteolytic degradation, the susceptibility of denatured proteins to processing, and the higher affinity of conformationally constrained 'extended' inhibitors/substrates for proteases. Other approaches to extended inhibitor conformations should similarly lead to high-affinity binding to a protease.

Chronic ethanol has region-selective effects on Egr-1 and Egr-3 DNA-binding activity and protein expression in the rat brain

This study focused on the DNA-binding activity and protein expression of the transcription factors Egr-1 and Egr-3 in the rat brain cortex and hippocampus after chronic or acute ethanol exposure. DNA-binding activity was reduced in both regions after chronic ethanol exposure and was restored to the level of the pair-fed group at 16 h of withdrawal. Cortical Egr-1 protein levels were not altered by chronic ethanol exposure but increased 16 h after withdrawal, thus mirroring DNA-binding activity. In contrast, Egr-3 protein levels did not undergo any change. There was no change in the level of either protein in the hippocampus. Immunohistochemistry revealed a region-selective change in immunopositive cells in the cortex and hippocampus. Finally, an acute bolus dose of ethanol did not affect Egr DNA-binding activity and ethanol treatment did not alter the DNA-binding activity or protein levels of the transcription factor Spl. These observations suggest that chronic exposure to ethanol has region-selective effects on the DNA-binding activity and protein expression of Egr-1 and Egr-3 transcription factors in the rat brain. These changes occur after prolonged ethanol exposure and may thus reflect neuroadaptive changes associated with physical dependency and withdrawal. These effects are also transcription factor-selective. Clearly, protein expression is not the sole mediator of the changes in DNA-binding activity and chronic ethanol exposure must have effects on modulatory agents of Egr DNA-binding activity. (C) 2000 Elsevier Science Ltd, All rights reserved.

Glutamate-mediated transmission, alcohol, and alcoholism

Glutamate-mediated neurotransmission may be involved in the range of adaptive changes in brain which occur after ethanol administration in laboratory animals, and in chronic alcoholism in human cases. Excitatory amino acid transmission is modulated by a complex system of receptors and other effecters, the efficacy of which can be profoundly affected by altered gene or protein expression. Local variations in receptor composition may underlie intrinsic regional variations in susceptibility to pathological change. Equally, ethanol use and abuse may bring about alterations in receptor subunit expression as the essence of the adaptive response. Such considerations may underlie the regional localization characteristic of the pathogenesis of alcoholic brain damage, or they may form part of the homeostatic change that constitutes the neural substrate for alcohol dependence. (C) 2000 Elsevier Science Ltd. All rights reserved.

Is ultra-rapid opioid detoxification a viable option in the treatment of opioid dependence?

Ultra-rapid opioid detoxification (UROD) involves the acceleration of opioid withdrawal hv administering thp opioid receptor antagonist naltrexone under general anaesthesia. There is evidence from uncontrolled and a few controlled studies that UROD accelerates opioid withdrawal and that it achieves high rates of completion of acute opioid withdrawal. However, there is clear evidence that the use of a general anaesthetic is not required to accelerate withdrawal or to achieve high rates of completion of acute opioid withdrawal. These goals can be achieved by using naltrexone or naloxone to accelerate withdrawal under light sedation, a procedure known as rapid opioid detoxification under sedation (ROD). There is also evidence that use of an opioid antagonist is not required to achieve a high rate of completion of acute opioid withdrawal. The mixed agonist-antagonist buprenorphine has achieved comparable rates of completion in similarly selected patients with fewer withdrawal symptoms. There is no evidence from controlled trials that either UROD or ROD increases the rate of abstinence from opioids 6 or 12 months after withdrawal. UROD and ROD may increase the number of patients who are inducted onto naltrexone maintenance (NM) therapy but extensive experience with NM therapy suggests that it only has a limited role in selected patients. Given the lack of evidence of substantially increased rates of abstinence, and the need for anaesthetists and high dependency beds, UROD has at best a very minor role in the treatment of a handful of opioid dependent patients who are unable to complete withdraw in any other way. ROD may have more of a role as one option for opioid withdrawal in well motivated patients who want to be rapidly inducted onto NM therapy or who want to enter other types of abstinence-oriented treatment.

Simultaneous steady state and dynamic design of process systems using structural indicators

The simultaneous design of the steady-state and dynamic performance of a process has the ability to satisfy much more demanding dynamic performance criteria than the design of dynamics only by the connection of a control system. A method for designing process dynamics based on the use of a linearised systems' eigenvalues has been developed. The eigenvalues are associated with system states using the unit perturbation spectral resolution (UPSR), characterising the dynamics of each state. The design method uses a homotopy approach to determine a final design which satisfies both steady-state and dynamic performance criteria. A highly interacting single stage forced circulation evaporator system, including control loops, was designed by this method with the goal of reducing the time taken for the liquid composition to reach steady-state. Initially the system was successfully redesigned to speed up the eigenvalue associated with the liquid composition state, but this did not result in an improved startup performance. Further analysis showed that the integral action of the composition controller was the source of the limiting eigenvalue. Design changes made to speed up this eigenvalue did result in an improved startup performance. The proposed approach provides a structured way to address the design-control interface, giving significant insight into the dynamic behaviour of the system such that a systematic design or redesign of an existing system can be undertaken with confidence.

Eutectic nucleation and growth in hypoeutectic Al-SI alloys at different strontium levels

The effects of different levels of strontium on nucleation and growth of the eutectic in a commercial hypoeutectic Al-Si foundry alloy have been investigated by optical microscopy and electron backscattering diffraction (EBSD) mapping by scanning electron microscopy (SEM). The microstructural evolution of each specimen during solidification was studied by a quenching technique at different temperatures and Sr contents. By comparing the orientation of the aluminum in the eutectic to that of the surrounding primary aluminum dendrites by EBSD, the eutectic formation mechanism could be determined. The results of these studies show that the eutectic nucleation mode, and subsequent growth mode, is strongly dependent on Sr level. Three distinctly different eutectic growth modes were found, in isolation or sometimes together, but different for each Sr content. At very low Sr contents, the eutectic nucleated and grew from the primary phase. Increasing the Sr level to between 70 and 110 ppm resulted in nucleation of independent eutectic grains with no relation to the primary dendrites. At a Sr level of 500 ppm, the eutectic again nucleated on and grew from the primary phase while a well-modified eutectic structure was still present. A slight dependency of eutectic growth radially from the mold wall opposite the thermal gradient was observed in all specimens in the early stages of eutectic solidification.