The origin and population dynamics of annually re-occurring Paratanytarsus grimmii (Diptera: Chironomidae) colonising granular activated carbon (GAC) adsorbers used in potable water treatment.

Various sampling techniques were employed to study the population dynamics and identify the origin of annually re-occurring infestations of Paratanytarsus grimmii in granular activated carbon (GAC) adsorbers. Larvae overwintered in all adsorbers studied and are the main source of endemic persistent infestations. Significant differences in larval densities were identified between the down-flow cell (mean of 61 larvae per 0.3 l of GAC) and the up-flow cell (mean of 14 larvae per 0.3 l of GAC) of each adsorber. Larvae were distributed uniformly with no significant difference in density at any depth through the 2-m carbon column. Application of anaerobic treatment as a control measure was ineffective at low temperatures due to a slow down in chironomid metabolism. During summer months, ovipositing females have access to all locations within the GAC adsorber building by flight, leading to immediate re-colonisation of anaerobically-treated adsorbers. Regeneration of GAC in individual cells served only to reduce larval numbers but not remove them completely, particularly when only one of the two cells is regenerated at any one time.

Molecular phylogeny of choanoflagellates, the sister group to Metazoa.

Choanoflagellates are single-celled aquatic flagellates with a unique morphology consisting of a cell with a single flagellum surrounded by a "collar" of microvilli. They have long interested evolutionary biologists because of their striking resemblance to the collared cells (choanocytes) of sponges. Molecular phylogeny has confirmed a close relationship between choanoflagellates and Metazoa, and the first choanoflagellate genome sequence has recently been published. However, molecular phylogenetic studies within choanoflagellates are still extremely limited. Thus, little is known about choanoflagellate evolution or the exact nature of the relationship between choanoflagellates and Metazoa. We have sequenced four genes from a broad sampling of the morphological diversity of choanoflagellates including most species currently available in culture. Phylogenetic analyses of these sequences, alone and in combination, reject much of the traditional taxonomy of the group. The molecular data also strongly support choanoflagellate monophyly rejecting proposals that Metazoa were derived from a true choanoflagellate ancestor. Mapping of a complementary matrix of morphological and ecological traits onto the phylogeny allows a reinterpretation of choanoflagellate character evolution and predicts the nature of their last common ancestor.

The effects of sediment size fraction and associated algal biofilms on the kinetics of phosphorus release.

Experiments using flumes containing sediment of three different size fractions, from two sites on the River Tame, investigated the influences of sediment particle size, and an associated biofilm, on sediment-water exchanges in heterogeneous sediment deposits. This is the first study undertaken to understand the kinetics of the release of soluble reactive phosphorus from sediments of natural systems to identify which of the size compartments affected those fluxes most. Samples of fine material (<2 mm), gravel (2-20 mm), and stones (>20 mm) were collected over a period of several weeks and brought to a fluvarium where they were placed in artificial, controlled flow, and flume channels. Synthetic solutions of similar ionic strength to the river were prepared using calcium chloride. Temperature, pH, and dissolved oxygen of the solution overlying the sediment were monitored automatically whilst filtered samples were obtained at 2 h intervals over 48 h. The biomass, expressed as mg m(-2) chlorophyll a, of the algal component of the biofilm from the surface of the sediment was estimated using methanol extraction. Differences in the responses were observed between the sediment size fractions and the two sites, where contaminant concentrations varied. The equilibrium phosphate concentration and a phosphorus transfer index were used to establish that there was a net uptake of phosphorus by all three sediment size fractions, from both sites, at the time of sampling. The kinetic results showed very fast initial reactions of phosphorus release from the larger size fractions with a well-developed filamentous algal growth present implying a different mechanism than diffusion being involved. The stones and associated biofilms also released more phosphorus than the fine fraction, e.g. final release concentrations for the most contaminated site were: fines approximately 2.5 microM, gravel approximately 6.5 microM, and stones approximately 65.0 microM (expressed as soluble reactive phosphorus). Phosphorus fluxes, calculated assuming the concentration of phosphorus in the sediment was less than the equilibrium concentration, were a maximum at the most contaminated site, e.g. fines 6.4 nmol m(-2) s(-1), gravel 27 nmol m(-2) s(-1), and stones 109 nmol m(-2) s(-1) (normalised with respect to the river bed area). These results confirm that sediment having a biofilm and associated particulate material results in a greater flux than fine sediment, which does not support a filamentous biomass. Removal of the fine particulates trapped in the algal growth reduced soluble phosphorus release. These factors demonstrate that both gravel and stone substrates have an important control over the release of soluble reactive phosphorus.

Kinetics of phosphorus release from a natural mixed grain-size sediment with associated algal biofilms.

Experiments using flumes containing mixed grain-size sediment with an associated algal biofilm, from two sites on the R. Tame, investigated the sediment-water exchanges in heterogeneous sediment deposits. These results were considered in the light of findings of a companion study [Gainswin BE, et al. The effects of sediment size fraction and associated algal biofilms on the kinetics of phosphorus release. Sci Total Environ, this issue.] by considering this natural system in relation to the effects of the different sizes of material comprising the sediment. Sediment samples were collected in trays installed in the river over a period of one growth cycle (March 2001-April 2002) and placed in flume channels with controlled water flow. The temperature, pH, and dissolved oxygen of the solution overlying the sediment were monitored automatically whilst filtered samples were obtained at 2-0h intervals over 48 h. The biomass, expressed as chlorophyll a, of the algal component of the biofilm from the surface of the sediment was estimated using methanol extraction. The composition of the sediment, viz. size fractions, organic matter and porosity, were determined at the end of the experiments. The equilibrium phosphate concentration and a phosphorus transfer index were used to establish that a net uptake of phosphorus by some of the samples that occurred at the time of sampling. The results were modelled using a Diffusion Boundary Layer model and the maximum flux from the sediment (or limiting diffusion flux) compared for each of the samples. The limiting diffusion flux was highest at the most contaminated site--reaching approximately 180 nmol m(-2) s(-1) (normalised with respect to the river bed area). The limiting diffusion flux calculated for the composite samples was in agreement with the flux estimated from the contributions expected from the individual size fractions [Gainswin BE, et al. The effects of sediment size fraction and associated algal biofilms on the kinetics of phosphorus release. Sci Total Environ, this issue.]. The dominance of the flux contribution from the stones size fraction (>20 mm) confirms that sediment having a filamentous biofilm and associated particulate material results in a greater flux than a silt sediment without such a biomass.

Levels of interpersonal concerns and social functioning in early adolescent boys and girls.

Previous research has shown that the Interpersonal Concerns factor of the Depressive Experiences Questionnaire (DEQ; Blatt, D'Affliti, & Quinlan, 1976, 1979; Depressive Experiences Questionnaire for Adolescent [DEQ-A]; Blatt, Schaffer, Bers, & Quinlan, 1992) assesses 2 levels of interpersonal relatedness in young adults and older adolescents: neediness and relatedness. However, studies investigating the relation of the DEQ and DEQ-A with social functioning have not used the Neediness and Relatedness subscales of the Interpersonal Concerns factor. This study investigated (a) whether the Neediness and Relatedness subscales can be differentiated in a sample of early adolescents and (b) how the 2 subscales are differentially associated with indexes of social functioning. Results indicate that this differentiation of Neediness and Relatedness, and their associations with social functioning, emerges in early adolescence, especially for girls.

Cyst formation in a freshwater strain of the choanoflagellate Desmarella moniliformis Kent.

Cyst formation in a freshwater strain of the colonial freshwater choanoflagellate Desmarella moniliformis Kent (Protozoa: Choanoflagellida) has been studied with light and electron microscopy for the first time. Batch cultures inoculated with motile vegetative cells start to produce cysts within 3 days during the exponential phase of growth. Cyst production proceeds until in late stationary phase there is a preponderance of cysts. Transfer of cysts to fresh medium results in limited excystment. Encystment involves the production of electron-dense fibrillar wall material, firstly around the neck of the cell and then around the posterior end. As the wall material is deposited the neck of the cell elongates and the dictyosome rotates from the horizontal to vertical plane. The number of mitochondrial profiles seen in individual sections of cells increases. Finally the neck of the cell is retracted, the flagellum and collar tentacles are withdrawn, and the bottom of the neck of the cyst wall is sealed with a diaphragm of wall material. Excystment, which has not been observed directly, appears to involve the disruption of the wall at the base of the neck, the remainder of the cyst wall remains intact. Comparisons are made between encystment in Desmarella and cyst development in other protists.

A multivariate model of gender differences in adolescents' internalizing and externalizing problems.

Gender differences observed in interpersonal and self-critical vulnerabilities, reactivity to stressful life events, quality of relationships, and self-concepts inform a multivariate theoretical model of the moderating effects of gender on internalizing and externalizing problems in adolescence. To test this model, data were collected in a 1-year prospective study from an ethnically diverse sample of 460 middle school students. Increases in girls' internalizing symptoms, compared with boys', were partly explained by greater stability in girls' interpersonal vulnerabilities and greater magnitude in coefficients linking girls' relationships with parents and peers and internalizing problems. Boys' risks for externalizing problems, compared with girls', were partly explained by the greater stability in boys' vulnerability to self-criticism. Coefficients for most pathways in the model are similar for boys and girls.

Maternal social support patterns and child maltreatment: comparison of maltreating and nonmaltreating mothers.

Compared to demographically matched mothers, maltreating mothers listed fewer friends in their social support networks, reported less contact with friends, and gave lower ratings of quality of support received from friends. Maternal depressive symptoms, quality of current relationships, and social support from friends were each independently associated with maltreatment status in logistic regression analysis. Implications for intervention and research are offered.

Pathways toward educational achievement among African American and Puerto Rican adolescent mothers: reexamining the role of social support from families.

Although a majority of adolescent mothers are graduating from high school, the processes that enhance the educational attainment of adolescent mothers are not well understood. With a sample of 93 African American and Puerto Rican adolescent mothers, we assessed the effects of material support from family (i.e., child care assistance from grandmother and residence with grandmother) and emotional support from family over and above pre- and postpregnancy risk factors (i.e., maternal age at first birth, delayed grade placement before pregnancy, ethnicity, depressive symptoms, stressful life events, and repeat pregnancy) during the first year postpartum on educational attainment at 6 years postpartum. Significant contributors to the explained variance in educational attainment included: delayed grade placement before pregnancy, maternal age at first birth, depressive symptoms, emotional support from family, and residence with grandmother. Unexpectedly, higher perceived emotional support from family and living with grandmother predicted lower educational attainment. Post hoc analysis of qualitative data suggested reasons for these latter findings and point to the need to reconceptualize and broaden the elements of social support that constitute protective factors for adolescent mothers.

School outcomes for minority-group adolescent mothers at 28 to 36 months postpartum: a longitudinal follow-up.

PIP: This study examines the educational status of 120 adolescent postpartum women in the US during 1987-88. Mothers were 14-19 years old at delivery. 53.1% were African American and 42.5% were Puerto Rican. All but 2 deliveries were first births. 71.7% lived with their own mothers. 64.6% came from families on welfare. The average number of years of completed schooling was 9.5. At 28-36 months postpartum the average age was 19.7 years, 52.4% lived with their mothers, 52.4% lived off their mother's public assistance, and 17.9% supported themselves. 7.9% were married. Interviews were conducted at 3-4 weeks, 6 months, 12 months, and 28-36 months postpartum. 94% had completed interviews by 12 months, and 71% had completed interviews by 28-36 months. 33% of mothers had attended school or graduated through the pregnancy and the last follow-up period. 19% who were not in school at the first birth returned or graduated by 28-36 months postpartum. 12% dropped out before the pregnancy and never returned; 36% dropped out during the pregnancy and never returned. Greater risk of delayed grade placement by 28-36 months was significantly associated with age at delivery and reports of stressful life events 1 year postpartum. Mothers who were more grade-delayed reported more depressive symptoms, more repeat pregnancies, and lower work plans. At 1 year postpartum, school returners reported significantly fewer stresses and more child care support than dropouts. 41% of the mothers had a new mate. 25.7% reported a close relationship with the baby's father. About 80% reported problems with the fathers such as drugs, promiscuity, jail, death, machismo, or physical abuse. Only 39% of attenders had a repeat pregnancy compared to 68% of returners, 93% of dropouts during pregnancy, and 70% of dropouts before pregnancy. Only half of the mothers were likely to pursue educational and occupational goals.^ieng

Regeneration of phosphorus and nitrogen by four species of heterotrophic nanoflagellates feeding on three nutritional States of a single bacterial strain.

Three physiological states of a single bacterial strain, namely, balanced, phosphorus-rich, and nitrogen-rich bacteria, were obtained by culturing a bacterial strain in chemostats under three different nutrient regimens. Each was shown to be distinctly different in elemental composition with respect to C/N/P ratio. These bacteria were fed to four species of heterotrophic nanoflagellates in batch culture grazing experiments, and the percent regeneration efficiencies of bacterium-bound nitrogen and phosphorus by the flagellates were compared. All flagellate species regenerated comparable amounts of nitrogen, which was thought to be due to their similar internal C/N ratios. There was, however, interspecies variation with regard to phosphorus regeneration: the two faster-growing species (Paraphysomonas imperforata and Bodo designis) released significantly more phosphorus than the two slower-growing species (Stephanoeca diplocostata and Jakoba libera). The observed differences were thought to have been influenced by a combination of life cycle strategies and internal C/P ratios.

Predictors of behavior problems in preschool children of inner-city Afro-American and Puerto Rican adolescent mothers.

Maternal reports on the Child Behavior Checklist/2-3 (CBCL/2-3) were used to evaluate child, maternal, and environmental predictors of behavior problems in 83 preschool children of disadvantaged adolescent mothers. CBCL/2-3 scores correlated modestly with independent ratings of child difficult behaviors observed in videotaped mother-child play interactions. 13% of children had scores in the clinical range. Significant correlations were consistently found between CBCL/2-3 ratings and maternal depressive symptoms, social supports, and life stress--assessed 3 times during the first year postpartum. In hierarchical regression analyses, maternal depressive symptoms, residence with the adolescent's mother, and perceived emotional support from friends contributed most to the explained variance. A significant ethnicity x child gender interaction term also suggested that African American mothers of male children reported more behavioral problems. Findings evidence the heterogeneity of outcomes for children of disadvantaged adolescent mothers but also demonstrate how correlates of poverty negatively affect their socioemotional development.

Predictors of repeat pregnancy outcome among black and Puerto Rican adolescent mothers.

This prospective study investigated predictors of repeat pregnancies by 12 months after the delivery of a first child and their outcomes in inner-city adolescent mothers. The sample included four groups: those who had therapeutic abortions, miscarriages, full-term deliveries, and no repeat pregnancy. The therapeutic abortion group had more pregnancies before their first delivery (41%) than did full term (20%) and no repeat (15%), p less than .01. More delayed grade placement was found in therapeutic abortion -1.6 years (1.3) and full term -1.8 years (.9) than in no repeat pregnancy -.6 years (1.1), p less .001. Reading achievement scores were higher in no repeat 86.3 (17.1) than in full term 75.0 (16.5), p less than .05. School attendance was higher in no repeat (65%) than in therapeutic abortion (35%) and full-term (24%) p less than .01 groups. Depressive symptoms at baseline were higher among therapeutic aborters 18.9 (9.9) than among full term 10.2 (8.2) and no repeat pregnancy groups 12.2 (6.2). Logistic regression analyses identified delayed grade placement as the most important predictor of pregnancy outcome.

PIP: The purpose of this prospective study of 120 black and Puerto Rican adolescent mothers recruited from an urban adolescent health center was 1) to identify multiple predictors of repeat pregnancies and their outcomes, and 2) to assess the relative contribution of these predictors to repeat pregnancies. Variables include demographic factors, frequency of sexual activity, contraceptive method used, occurrence of pregnancies before the first delivery, educational attainment, and levels of depressive symptoms by 3 weeks postpartum. Pregnancy outcomes included mothers who terminated their pregnancy, who delivered a live birth, and who had a miscarriage; data were available 12 months postpartum. The mean age was 17.13 years. 52% were black and 44% were Puerto Rican and of low socioeconomic status. Reliability of self-reports was 95%. 60.3% had no repeat pregnancy and 39.6% became pregnant during the 1-year followup, of which 15.3% had a therapeutic abortion, 6.3% miscarried, and 18.1% carried to term. There were no significant differences in the characteristics of the repeat and nonrepeat pregnancy groups. The procedure involved interviews at 2-4 weeks (time 1), 6-7 months (time 2), and 12-13 months (time 3). Measures for delayed grade placement, reading achievement, career aspirations and socioeconomic status of the family, and school attendance are described. Multivariate analysis, univariate analyses, and Duncan multiple range tests were conducted as well as logistic regression model construction. The significant predictors of pregnancy outcome (repeat pregnancy) were having 2 or more previous pregnancies. The abortion group was twice as likely to have had a pregnancy before the birth of the first child (41%) than the full-term (20%) and the no-repeat groups (15%). There were no differences in frequency of sexual activity or contraceptive method used. In the no-repeat and miscarriage groups, grade placement was less delayed. In the no-repeat group, reading achievement scores were higher than in the full-term group. There were no differences in career aspirations. 65% of the no-repeat group were attending school at time 2 while only 35% of the therapeutic and 24% of the full-term groups were attending school. Depressive scores were significantly higher for the abortion group. Delayed grade placement was the only predictor independently associated with the increased log odds of repeat pregnancy.

Adolescent problem behaviors: the influence of attachment and autonomy.

This article reviews current literature on adolescent problem behaviors and suggests that a model based on attachment theory and theories of adolescent autonomy and relatedness can help explain the development of these behaviors. When adolescents hold models of relationships with parents that are characterized by anger and insecurity and face increased pressures to seek autonomy, a high risk of problem behaviors ensues. Treatment implications flowing from this model are discussed.

Frequency of use, knowledge, and attitudes toward the contraceptive sponge among inner-city black and Hispanic adolescent females.

This study assessed the frequency of use, knowledge, and attitudes toward the contraceptive sponge in sexually active, inner-city, black and Hispanic adolescent females. A 54-item, self-administered questionnaire was completed by 208 adolescents (mean age 17.9 years) attending a gynecology/family planning clinic within a comprehensive adolescent health center. Twenty-nine (13.9%) had never used any birth control, and 49 (23.6%) had not used any form of birth control in the 3 months prior to the study. Fifty-three (25.5%) of the adolescents had used a less reliable method such as rhythm and/or withdrawal. The birth control method used least was the sponge. Only four (1.9%) of the adolescents had used the sponge in the 3 months prior to the study, and only ten (4.8%) had ever used it. Knowledge of the correct use of the sponge was poor. However, 69 (44.8%) of the 156 girls who knew about the sponge had a positive attitude toward it, and only 19% said they did not like it. The contraceptive sponge may be a viable option for adolescents, particularly those who are not using birth control or who are using a less reliable method.

PIP: This study assessed the frequency of use, knowledge, and attitudes toward the contraceptive sponge in sexually active, inner-city black and Hispanic adolescent females. A 54-item self-administered questionnaire was completed by 208 adolescents (mean age 17.9 years) attending a gynecology/family planning clinic within a comprehensive adolescent health center in New York City. 29 (13.9%) had never used any birth control and 49 (23.6%) had not used any form of birth control in the 3 months prior to the study. 53 (25.5%) of the adolescents had used a less reliable method such as rhythm and/or withdrawal. The birth control method used least was the sponge. Only 4 (1.9%) of the adolescents had used the sponge in the 3 months prior to the study and only 10 (4.8%) had ever used it. Knowledge of the correct use of the sponge was poor. However, 69 (44.8%) of the 156 girls who know about the sponge had a positive attitude toward it and only 19% said they did not like it. The contraceptive sponge may be a viable option for adolescents, particularly those who are not using birth control or who are using a less reliable method.

Characteristics of social networks in adolescents with end-stage renal disease treated with renal transplantation.

In adolescents, the establishment of same- and opposite-sex nonfamily peer relations facilitates the normal development of independence and separation from family. Adolescents with end-stage renal disease (ESRD) may be particularly vulnerable to delayed social development and isolation from their peers because of the unique physical and psychosocial aspects of their illness. The characteristics of the social networks of 16 adolescents with ESRD treated with renal transplantation were studied using the Social Networks of Youth Questionnaire. Compared with a matched group of healthy adolescents, these teenagers named fewer significant others in their total social networks, as well as fewer unrelated and opposite-sex peers. Family members comprised a greater proportion of the transplant patients' networks compared to controls. Self-esteem, measured by the Coopersmith Self-Esteem Scale, was similar for transplant and control groups, with the exception of home self-esteem, which was higher in the chronically ill adolescents. Body image was somewhat lower, but not significantly, in adolescents with ESRD. The characteristics of the chronically ill adolescents' social networks suggest that these patients may experience a degree of social isolation. Interventions that promote increased peer contacts and enhance interpersonal skills should be included in the psychosocial management of adolescents with ESRD after renal transplantation.

Anal intercourse and knowledge of acquired immunodeficiency syndrome among minority-group female adolescents.

PIP: Adolescent minority group females experience of anal intercourse and knowledge about and attitudes toward AIDS have been investigated. A questionnaire survey was administered to 148 largely black and Hispanic female patients at an adolescent health center. 111 of the girls reported that they were sexually active. 28 girls (25.2%) acknowledged having had anal sex, 19 of them within the preceding 3 months. Condoms were far less likely to be used during anal intercourse than during vaginal sex. Accurate knowledge about AIDS increased with age, but there was no relationship between age and any change in sexual behavior to avoid the disease. What little changes in sexual behavior reported were, however, strongly linked to fear of contracting AIDS. The most effective means of HIV transmission from males to females is through anal intercourse. Given the high incidence of anal intercourse practice by black and Hispanic females, their infrequent use of condoms during anal intercourse, and a large and increasing HIV infection rate among black and Hispanic males, it can be seen that adolescent minority group females are at increasing risk of heterosexual exposure to HIV infection. Lack of relationship between knowledge about AIDS and reduction of high-risk sexual behavior are discouraging to hopes of disease prevention through educational efforts.^ieng

The limits of reciprocity in behavioral marriage therapy.

This reexamination of the values underlying Behavioral Marriage Therapy (BMT) focuses on the central theoretical concept of reciprocity. It is suggested that BMT's emphasis on individuality and instrumental exchange may not be suitable for all couples. An alternative perspective, emphasizing a developmental progression in marriage reciprocity defined by mutual understanding, is seen to be more sensitive to the differing value systems of couples in therapy.

Developmental and ultrastructural observations on two stalked marine choanoflagellates, Acanthoecopsis spiculifera Norris and Acanthoeca spectabilis Ellis.

Acanthoecopsis spiculifera and Acanthoeca spectabilis are stalked, loricate choanoflagellates found in littoral sea water pools. The two taxa are distinguished from each other by the arrangement of costae forming the lorica chamber. In addition, Acanthoecopsis spiculifera usually has a longer stalk and may be colonial, consisting of two or more attached individuals. Division in Acanthoeca results in the production of a juvenile, flagellated, protoplast without a lorica. After separation, the juvenile protoplast swims away, settles down and produces an accumulation of costal strips. When sufficient strips have been produced the lorica is rapidly assembled.