PubMed Health⌕ Search

Biomedical subjects

C Howes

Publications and source records attributed to C Howes.

At least 19 recordsLinked to original sources
PubMed2005

Detailed observation and measurement of sewer sediment erosion under aerobic and anaerobic conditions.

A greater understanding of the erosion behaviour of sewer sediments is necessary in order to reliably estimate the amount and nature of the sewer sediments released from deposits in sewers and transported either to waste water treatment plants or discharged into the environment. Research has indicated that microbial activity in sediment can influence the physical release of sediment from in-pipe deposits. This paper reports on a series of erosion tests in which sewer sediments from different sewer networks are kept under different environmental conditions and their resistance to erosion is examined. The erosion tests are carried out under aerobic and anaerobic conditions and two temperatures, one representing ambient sewer temperatures and a lower temperature that significantly suppresses bacterial activity.

Aerobiosis↗
PubMed2002

Evidence for an atypical receptor mediating the augmented bronchoconstrictor response to adenosine induced by allergen challenge in actively sensitized Brown Norway rats.

The bronchoconstrictor response to adenosine is markedly and selectively increased following ovalbumin (OA) challenge in actively sensitized, Brown Norway rats. We present a pharmacological analysis of the receptor mediating this response. Like adenosine, the broad-spectrum adenosine receptor agonist, NECA, induced dose-related bronchoconstriction in actively sensitized, OA-challenged animals. In contrast, CPA, CGS 21680 and 2-Cl-IB-MECA, agonists selective for A(1) A(2A) and A(3) receptors, respectively, induced no, or minimal, bronchoconstriction. Neither the selective A(1) receptor antagonist, DPCPX, nor the selective A(2A) receptor antagonist, ZM 241385, blocked the bronchoconstrictor response to adenosine. MRS 1754, which has similar affinity for rat A(2B) and A(1) receptors, failed to block the bronchoconstrictor response to adenosine despite blockade of the A(1) receptor-mediated bradycardia induced by NECA. 8-SPT and CGS 15943, antagonists at A(1), A(2A), and A(2B) but not A(3) receptors, inhibited the bronchoconstrictor response to adenosine. However, the degree of blockade (approximately 3 fold) did not reflect the plasma concentrations, which were 139 and 21 times greater than the K(B) value at the rat A(2B) receptor, respectively. Adenosine and NECA, but not CPA, CGS 21680 or 2-Cl-IB-MECA, induced contraction of parenchymal strip preparations from actively sensitized OA-challenged animals. Responses to adenosine could not be antagonized by 8-SPT or MRS 1754 at concentrations >50 times their affinities at the rat A(2B) receptor. The receptor mediating the bronchoconstrictor response to adenosine augmented following allergen challenge in actively sensitized BN rats cannot be categorized as one of the four recognized adenosine receptor subtypes.

Adenosine↗
PubMed1999

Attachment organizations in children with difficult life circumstances.

The purpose of this study was to use the Attachment Q-Set to create categories of attachment organization that were conceptually consistent with organizational categories derived from other attachment assessments, reliable, and valid. We were particularly interested in creating categories that would describe insecure attachment organizations in children from difficult life circumstances. Our sample of relationships included 3062 teacher-child relationships. Children ranged in age from toddlers to kindergartners and were diverse in ethnic background. Two percent of the children were diagnosed with severe social and emotional problems and enrolled in a therapeutic preschool. Sixteen percent were enrolled in intervention programs on the basis of family poverty and another 34% of the children attended subsidized child care programs for low-income children. All of the children's child-teacher relationships were assessed with the Attachment Q-Set (AQS). Independent observers observed or rated children's peer play. Teachers completed behavior problem questionnaires and Student Teacher Relationships Scales. Using the AQS we created five subscales and six attachment organizational categories. These subscales and organizational categories were associated in theoretically meaningful ways with measures of behavior problems, social competence with peers, and teacher perceptions of child-teacher relationship.

Avoidance Learning↗
PubMed1998

Stability and continuity of child-caregiver and child-peer relationships.

We examined the relationship quality of 55 (27 girls) 9-year-old children with their mothers, teachers, and friends as rated by teachers and by the children themselves. The goal of this longitudinal study was to examine stability and continuity in the quality of children's relationships between infancy and 9 years of age. At age 9, children's perception of their relationships with their teachers was associated with their current teachers' ratings of their relationships with the children. Children's perceptions of their relationships with their mothers were consistent with earlier ratings of attachment security. Children's perceptions of their relationships with teachers were predicted by the quality of their attachment relationships with their first teachers. Children's perceptions of their friendship quality was predicted by preschool teacher ratings of friendship quality and the quality of their attachment relationships with their first teachers.

Child↗
PubMed1996

Gender differences in children's normative beliefs about aggression: how do I hurt thee? Let me count the ways.

This research was designed to assess whether children view relationally manipulative behaviors (i.e., those behaviors labeled relational aggression in past research) as "aggressive." 2 studies were conducted to evaluate whether children view relationally manipulative behaviors as associated with 2 defining features of aggression, anger (Study 1) and intent to harm (Study 2). Results of Study 1 (n = 459, 9-12-year-olds) indicated that relational aggression was the most frequently cited angry behavior for girls' interactions whereas physical aggression was the most frequently cited angry behavior for boys' interactions. Results of Study 2 (n = 60, 9-11-year-olds) demonstrated that relational aggression and verbal insults were the most frequently cited harmful behaviors for girls whereas physical aggression and verbal insults were the most frequently cited harmful behaviors for boys. These studies provide the first evidence that children view relationally manipulative acts (relational aggression) as angry, harmful behaviors (i.e., as "aggressive").

Aggression↗
PubMed1994

Children's relationships with peers: differential associations with aspects of the teacher-child relationship.

Associations between children's social competence with peers and differential aspects of their teacher-child relationships were examined in a longitudinal sample of 48 4-year-old children enrolled in child care as infants. Toddler security with teacher was negatively associated with hostile aggression and positively with complex peer play and gregarious behaviors. Prosocial behaviors and withdrawing behaviors were associated with preschool security with teacher. Dependence on teachers as a preschooler was associated with social withdrawal and hostile aggression. Positive toddler teacher socialization was associated with higher perceived peer acceptance. Preschool teacher negative socialization was negatively associated with complex peer play, teacher ratings of hesitancy, friendly enactment, and accidental attribution and positively related to teacher ratings of difficulty.

Child Behavior↗
PubMed1994

Maternal, teacher, and child care history correlates of children's relationships with peers.

Mother and teacher correlates of social competence with familiar and unfamiliar peers in 84 children who entered child care at three different times are examined. Social competence at age 4 was assessed with both familiar and unfamiliar peers. Relationships with both initial and 4-year-old teachers were related to social competence with peers. Maternal attachment relationships at 12 months and at 4 years did not predict social competence with peers.

Child↗
PubMed1994

Child care for children in poverty: opportunity or inequity?

Data from a nationally representative survey of child care centers and a 5-site, observational study of centers were used to examine the quality of care provided to children from low-income families. Comparisons were made to a national sample of centers; among Head Start, public school-sponsored, and other community-based subsidized centers; and among centers that served families from differing socioeconomic groups. The quality of care in centers that served predominantly low-income children was adequate, but highly variable, with structural indices exhibiting higher quality than observations of global quality and of staff-child interactions. When compared to Head Start and public school-sponsored centers, the community-based centers had smaller groups and fewer children per teacher for preschoolers, but also had less well educated and compensated staff. Centers that predominantly served children from upper-income families provided the highest quality of care across multiple indices, and those that predominantly served children from middle-income families almost uniformly provided the poorest quality of care. The centers that served children from low-income families did not differ significantly in quality from the upper-income centers on most indices. However, the teachers in these programs were observed to be less sensitive and more harsh than teachers in the centers that served more advantaged families. The implications of the findings for research and policy are discussed.

Child Day Care Centers↗
PubMed1992

Reduction of cardiovascular and thyroxine-suppressing activities of L-T3 by liver targeting with cholic acid.

This study was designed to determine whether the conjugation product of L-T3 with cholic acid would result in a liver-targeted compound (CGH 509A) with hypocholesterolemic (HC) activity significantly dissociable from cardiovascular (CV) and thyroxine-suppressing (TS) effects normally observed with thyroid hormone. Evaluation of HC activity in lipemic rats showed that CGH 509A was 6 times less potent than L-T3 with ED25 values estimated at 150 and 25 nmol/kg, respectively. CV function measured as changes in atrial rate, atrial tension and heart weight was determined in euthyroid rats. CGH 509A was at least 64 times less cardio-stimulant than L-T3 with minimum effective doses estimated at 2350 and 37 nmol/kg, respectively. TS activity was assessed in euthyroid rats as the potency of any compound to reduce plasma T4 levels. CGH 509A was 50 times less potent than-L-T3 with ED50 values estimated at 900 and 18 nmol/kg, respectively. From these results, it is clear that, while L-T3 was equally potent on HC, CV and TS activities, the HC potency of CGH 509A was at least 15 and 6 times greater than its CV and TS potencies, respectively.

Animals↗
PubMed1992

The social policy context of child care: effects on quality.

Examined effects on the quality of children's child care environments of (a) the stringency of state child care regulations, (b) voluntary compliance with proposed federal child care standards, and (c) the legal auspice of the center. Quality of care was assessed in 227 child care centers in five metropolitan areas. Centers in states with more stringent child care regulations tended to have better staff-child ratios, staff with more child-related training, and lower staff turnover rates. Similarly, centers that more fully complied with the ratio, group size, and training provisions of a set of proposed federal child care standards had significantly lower staff turnover rates, more age-appropriate classroom activities, less harsh and more sensitive teachers, and more teachers with specialized training. For-profit centers offered children less optimal care than did nonprofit centers. These findings are placed in the context of ecological models of research and of contemporary policy debates about child care.

Child↗
PubMed1992

Thresholds of quality: implications for the social development of children in center-based child care.

We assessed the quality of center child care relationships with adults and peers for 414 children (ages 14 to 54 months). Classrooms were classified by ratio and group size provisions of the Federal Interagency Day Care Requirements (FIDCR) and by the Early Childhood and Infant and Toddler Environmental Rating Scales. Children cared for in classrooms meeting FIDCR ratios were more likely to be in classrooms rated as good or very good in caregiving and activities. Children in classrooms rated as good or very good in caregiving were more likely to be securely attached to teachers. Securely attached children were more competent with peers. Children cared for in classrooms meeting FIDCR group size were more likely to be in classrooms rated higher in activities. Children in classrooms rated high in activities were likely to orient to both adults and peers. Children with social orientations to adults and peers were more competent with peers.

Child Behavior↗
PubMed1992

Children's relationships with caregivers: mothers and child care teachers.

Infant, toddler, and preschool children's relationships with mothers and teachers were examined in this study. 110 children were observed with their mothers during child care arrivals and reunions. 403 children were observed with their teachers in child care. 3 categories of relationships were derived from these observations. Children in the secure relationship category experienced more teacher involvement than children in the avoidant or ambivalent relationship categories. Children in the ambivalent relationship categories experienced more teacher involvement than children in avoidant relationship categories. A subsample (n = 23) of children were seen with their mothers both during child care arrivals and reunions and in the Strange Situation. Relationship classifications were similar.

Caregivers↗
PubMed1992

Children's relationships with child care teachers: stability and concordance with parental attachments.

In order to examine caregiving relationships of children enrolled in childcare, two longitudinal samples of children, n = 72 and n = 106, were followed from infancy through preschool. Maternal attachment as assessed by the Strange Situation, 4-year-old reunion behavior, and by the Attachment Q-Set tended to be stable across time. Children's teacher-child relationship quality, as measured by the Attachment Q-Set, was stable if the teacher remained the same. When the teacher changed, teacher-child relationship quality tended to be unstable until the children were 30 months old. After 30 months, relationship quality with teachers tended to be stable regardless of whether or not the teacher changed. Maternal and teacher relationships were nonconcordant. There were few interactions between adult caregiver relationship quality and age of entry into child care or intensity of child care.

Caregivers↗