Ultrasonic attenuation by nanoporous particles. Part I: theory.

Porous colloidal particles can dissipate ultrasonic energy at a much greater rate than solid particles of the same size and density. In this paper the mechanism for this extra dissipation is described, and a theoretical formula for the attenuation is derived for particles with interconnected pores. In Part II (William N. Rowlands, James K. Beattie, Alex M. Djerdjev, and Richard W. O'Brien, Phys. Chem. Chem. Phys., 2006, DOI: 10.1039/b605617m) this formula is compared to measurements on some porous particle systems.

Early adolescents' substance use and life stress: concurrent and prospective relationships.

Life stress during early adolescence has been linked to substance use. Few studies have investigated whether the amount of control the child has over stress moderates this relationship even though the role of personal control is of increasing theoretical importance. Relationships between controllable and uncontrollable life stress and substance use were investigated in 303 urban, African-American fourth and fifth graders (152 males, 151 females). Controllable life stress contributed to six regression equations predicting children's substance use both cross-sectionally and longitudinally, even when selected demographic and personal variables were controlled. Evidence supporting a similar role for uncontrollable life stress was not found.

Parental and peer influences on food consumption of preschool African-American children.

Sources of social influence on urban African-American preschool children's food consumption were coded from videotapes of noontime and evening meals of 42 children. The frequency of eating prompts was associated with the age of the child, the source (mothers, fathers, age mates, other adults, and day-care staff), and socioeconomic status. The success of the prompt in changing the child's eating behavior was dependent on the type of prompt.

Comparison of dietary intake methods with young children.

To select a valid method for obtaining dietary intake of preschool children, food intake of 17 children (8 in daycare programs and 9 in home care) was measured for three days. Each day, home caregivers and daycare staff were asked to recall what the child had eaten during the previous 24 hours. After the third day, the Willett Food Frequency Questionnaire was administered to assess intake during the preceding seven days, which included the three days of measured foods. There were no significant differences between means from measured and recalled intake. Although the children's gender and care status (daycare versus home care) made no difference in measured intake, there were significant differences in recalled intake for energy and percent of calories from saturated fat. In this study the questionnaire did not provide an accurate assessment of measured intake and could not replace the dietary recall.

How maternal characteristics influence differences between mothers' and teachers' ratings of Type A behavior in black preschool children.

Because of the increased use of reports of Type A behavior pattern (TABP) in preschool-age children, parents are sometimes asked to provide reports on their children in circumstances in which teachers' reports may be inappropriate or unavailable. This article contrasts mothers' and teachers' reports of TABP for 158 urban, black preschool children. Mothers provided self-reports of their own Type A behavior (FTAS). Mothers' scores were weakly correlated with teachers' scores and the FTAS reports. Mothers' reports of TABP for the children were significantly higher than those of the teachers. Reports of children's TABP by high-Type A mothers were significantly higher than reports by low-Type A mothers, whereas teachers' reports showed no difference between children of low- and high-TABP mothers. Results are discussed in terms of how some mothers may project personal characteristics onto their children and how the findings can be used in interpreting mothers' reports.

Investigating children's knowledge and understanding of AIDS.

Though AIDS education in schools reaches many adolescents, the incidence of adolescent HIV infection has risen dramatically. Reasons for failure to properly educate adolescents include not educating children prior to adolescence and neglecting to assess and address children's varying levels of cognitive development when designing AIDS education programs. Citing examples from a study of more than 600 elementary-age schoolchildren, this paper focuses on the importance of assessing children's understanding of disease processes rather than accepting their use of key phrases in appropriate contexts as reflecting knowledge, and using the level at which they understand disease processes rather than age as the primary determinant of students' readiness for comprehending AIDS-related concepts. Guidelines for assessing how well children understand disease processes, including use of nonleading probes, are presented.

Relationships among black families' cardiovascular disease risk factors.

BACKGROUND: As participants in the District of Columbia Studies of Children's Activity and Nutrition (D.C. SCAN), 262 black mothers and two of each mother's children (3-4 and 8-10 years of age) were measured in their homes for selected cardiovascular disease risk factors: serum total cholesterol, systolic and diastolic blood pressures, height and weight for body mass index, fitness (sum of pulses), activity, and triceps and subscapular skinfolds. RESULTS: For each measure, mothers in the highest quartile were more likely to have children who were also in the highest quartile, and mothers in the lowest quartile were more likely to have children who were in the lowest quartile. For the physiological measures, (with the exception of systolic blood pressure), correlations tended to be stronger between the siblings than between the younger child and the mother, and older siblings' physiological measures contributed to the prediction of younger siblings' physiological measures after controlling for mothers' physiological measures. Relationships between family cardiovascular disease risk factor history and children's serum total cholesterol, and systolic and diastolic blood pressure levels tended to be gender related; i.e., family cardiovascular disease risk factors on the mother's side were more likely to be related to levels among the female but not the male children and vice versa. When personal characteristics were controlled for, the family's cardiovascular disease history was related more strongly to the younger than to the older sibling's systolic and diastolic blood pressure levels. CONCLUSIONS: Results tend to substantiate the importance of screening and counseling other family members, especially a child of the same gender as the parent with a cardiovascular disease or an elevated risk factor level.

You Can Control Asthma: evaluation of an asthma education program for hospitalized inner-city children.

A self-management education program was designed for staff nurses to offer children while they received medical care for asthma in the hospital. The program uses videotapes, written activity books and nurse discussion with the patient. Evaluation was conducted to assess program feasibility and impact. Pre- and post-tests of 40 children age 6-12 years revealed that the children had statistically significant increases in knowledge of and expected response to early warning signs of acute asthma, and in their sense of personal control (Health Locus of Control). Parents reported an increased use of asthma self-management techniques for acute episodes of asthma. Medical record review for a 15 month pre- and post-period indicated reductions in emergency room use. Inpatient hospital based education offers a critical opportunity to introduce asthma management skills, especially to children not reached by more traditional programs.

Obesity, self-esteem, and health locus of control in black youths during transition to adolescence.

Abstract A three-year longitudinal study of 1,003 urban black children, ages nine through 12, explored the relationship between obesity, health locus of control, and self-esteem. Subjects were classified as obese or not-obese at two times, approximately two years apart. From Time 1 to Time 2, subjects were categorized as remaining the same, or either changing from obese to non-obese or non-obese to obese. Measures included the Children's Health Locus of Control scale (CHLC), the Rosenberg Self-Esteem scale (SE), and ponderosity (weight relative to height). SE and CHLC improved across the entire sample. Multiple regression analyses indicated that baseline self-esteem was associated with decreased ponderosity only for subjects who changed from obese to non-obese. Group differences imply that building self-esteem and acknowledging individual differences may facilitate treatment of adolescent obesity. Continued research is recommended.

Stability in a measure of children's health locus of control.

Increased interest in children's health locus of control has precipitated continued examination of the psychometric properties of scales measuring this concept. The Children's Health Locus of Control scale (CHLC) was administered to more than 1,000 urban black students in each of four years across three grade levels: Year 1 - grades four-six to Year 4 - grades seven-nine. Factor analyses revealed five factors forming scales with acceptable reliability at each year. Students' beliefs that they have control over their own health increased as a function of age. Beliefs in self-control had low, negative correlations with measures of external control. Stability of CHLC and the relatively simple procedure (16 dichotomous items) suggest that, despite problems with wording of some items, CHLC is an appropriate and efficient measure for comparing cross-sectional and longitudinal samples in this age range.

Bacteria associated with four species of Dacus (Diptera: Tephritidae) and their role in the nutrition of the larvae.

The bacteria associated with Dacus tryoni (Froggatt), Dacus jarvisi (Tryon), Dacus neohumeralis (Hardy) and Dacus cacuminatus (Hering) were examined. Bacteria were isolated from the surface of freshly-laid eggs, from within surface sterilised pupae, from heads and abdomens of wild and laboratory-maintained flies, and from decomposed fruits in which the wild larvae were feeding. A more diverse flora was associated with D. tryoni and D. jarvisi (15 and 14 species, respectively) than with D. neohumeralis and D. cacuminatus (9 and 6 species, respectively). Most of the bacteria belonged to the family Enterobacteriaceae and while there were similarities of bacterial associations between fly species there was no evidence of a strict symbiotic association of a particular bacterium or bacteria with each species of fly. The larvae of D. jarvisi were unable to develop normally in an artificial medium containing unhydrolysed protein and free of bacteria and on a medium containing casein and Serratia liquefaciens (isolated from the flies and shown to secrete protease) the larvae died. On the same casein medium containing Enterobacter cloacae (isolated from the flies and shown to be protease negative) the larvae developed normally. Larvae of D. tryoni and D. jarvisi were devoid of protease and cellulase activity, but contained some amylase activity. The significance of these results in terms of current hypotheses concerning symbioses between tephritids and bacteria is discussed.

Metabolism of three active analogues of the male antifertility agent alpha-chlorohydrin in the rat.

1. Two ketal derivatives of alpha-chlorohydrin, which possess male antifertility activity, have been synthesized labelled with 36Cl. Both are metabolized by the rat to beta-chloroacetic acid. 2. Neither derivative inhibited the glycolytic enzymes glyceraldehyde 3-phosphate dehydrogenase and triosephosphate isomerase. 3. The epoxide glycidol is metabolized to beta-chlorolactic acid, presumably by first being converted to alpha-chlorohydrin. 4. It is proposed that the male antifertility actions of these three analogues is due to their biotransformation to alpha-chlorohydrin, which is then metabolized within mature sperm to a compound which is an inhibitor of glycolysis.

Influence of growth environment on the phosphoenolpyruvate: glucose phosphotransferase activities of Escherichia coli and Klebsiella aerogenes: a comparative study.

A consistent difference was found between glucose-limited cultures of Escherichia coli and Klebsiella aerogenes strains in the manner which their apparent cellular content of glucose:phosphoenolpyruvate phosphotransferase (glucose-PTS) varied with growth rate. With the former strains, activity increased as a function of growth rate; in the latter it decreased. However, under glucose-sufficient conditions (potassium- or ammonia-limitation) both species behaved similarly; the glucose-PTS activity was lower and bore no obvious relationship to the rate of glucose consumption expressed by the growing culture. These results are discussed in relation to the role of glucose as a regulator of glucose-PTS synthesis, and to the likely contribution which the glucose-PTS makes to the overall rate of glucose uptake, particularly by cells gorwing in glucose-sufficient environments.

Glucose phosphoenolpyruvate phosphotransferase activity and glucose uptake rate of Klebsiella aerogenes growing in chemostat culture.

Glucose-limited cultures of Klebsiella aerogenes NCTC 418 (and the supposedly identical strain NCIB 418) possessed a glucose phosphoenolpyruvate (PEP) phosphotransferase activity that varied markedly and progressively with growth rate, from more than 250 nmol min-1 (mg dry wt cells)-1 at D = 0.1 h-1 to less than 100 nmol min-1 (mg dry wt cells)-1 at D = 0.8 h-1. When relieved of the glucose limitation, substrate was used at a rate that bore no precise relationship to the cells' phosphotransferase activity. Similarly, glucose-sufficient (phosphate- or potassium-limited) cultures metabolized glucose at high rates, whereas the cells possessed only moderate glucose PEP phosphotransferase activities. These results are compared with those reported for glucose-limited cultures of Escherichia coli and for variously limited cultures of K. aerogenes. Glucose-sufficient cultures, as well as glucose-limited cultures that had been temporarily relieved of glucose limitation, excreted partially oxidized products of glucose catabolism in considerable amounts. The relevance of this 'overflow' metabolism to studies of glucose transport using [U-14C]glucose is emphasized.

Bacteria from the gut of Australian termites.

The major gut bacteria of the worker caste of nine species of Australian termites, belonging to four families, were isolated and identified to generic level. All species were either facultative anaerobes or strict aerobes. A correlation appears to exist between the major gut bacterium and the family to which the termite belongs. The major bacterium from the two lowest termites, Mastotermes darwiniensis (family Mastotermitidae) and Cryptotermes primus (family Kalotermitidae), was Streptococcus; from four species belonging to the Rhinotermitidae (Heterotermes ferox, Coptotermes acinaciformis, C. lacteus, Schedorhinotermes intermedius intermedius) it was Enterobacter; and from three species of the Termitidae (Nasutitermes exitiosus, N. graveolus, N. walkeri) it was Staphylococcus. Enterobacter was a minor symbiont of M. darwiniensis, C. primus, and N. graveolus; Streptococcus was a minor symbiont of H. ferox, C. lacteus, S. intermedius intermedius, and N. exitiosus; and Bacillus was a minor symbiont of C. acinaciformis and S. intermedius intermedius. M. darwiniensis possessed another minor symbiont tentatively identified as Flavobacterium. C. acinaciformis from three widely separated locations possessed a similar microbiota, indicating some form of control on the composition of the gut bacteria. Bacteria, capable of growth on N-free medium in the presence of nitrogen gas, were isolated from all termites, except N. exitiosus and N. walkeri, and were identified as Enterobacter. No cellulose-degrading bacteria were isolated.

Metabolism of D- and L-lactate by Pseudomonas putida.

Pseudomonas putida grew at the same rate with the same molar growth yield on D-, L, or DL-lactate as the sole source of carbon for growth. D- and L- lactate were utilized simultaneously and at the same rate when the organism was grown on DL-lactate (ratio of D isomer to L isomer of 1:1). Growth on either isomer alone, or in combination, caused the induction of both a D-lactate, and an L-lactate dehydrogenase. Both enzymes were particulate and used dichlorophenolindophenol, or oxygen, but not NAD, as electron acceptor, and were inhibited by cyanide when oxygen was the electron acceptor. The pH optimum for the D-lactate dehydrogenase was about 6.5, and for the L-lactate dehydrogenase was about 8.0. The D-lactate dehydrogenase was more heat-sensitive than the L-lactate dehydrogenase. The stoichiometry of both enzyme reactions was the same with 2 mol of lactate dehydrogenase. The stoichiometry of both enzyme reactions was the same with 2 mol of lactate being oxidized by 1 mol of oxygen to form 2 mol of pyruvate. No lactate racemase was detected in the cell extracts.