RESUMEN
Fire is a critical ecosystem process in many landscapes and is particularly dominant in the chaparral shrublands of southern California which are also exposed to high levels of atmospheric N deposition. Few studies have addressed the combined effects of these two disturbance factors. In this study we evaluate the hydrologic and biogeochemical response of a control and a prescribed burn catchment over a 15-year period. Streamwater nitrate concentrations and export in the burned catchment were higher than those in the unburned catchment for 7-10 years after the burn and concentrations remained high in both catchments during the entire study. Therefore, fire is not an effective mitigation tool for N deposition in these semi-arid systems. Additionally, the extended N export in this system indicates that chaparral ecosystems do not recovertheir N retention capabilities as rapidly as humid systems do when subjected to disturbance.
Asunto(s)
Incendios , Nitrógeno/química , Contaminantes Atmosféricos , California , Conservación de los Recursos Naturales , Ecología , Ecosistema , Ambiente , Monitoreo del Ambiente , Plantas , ÁrbolesRESUMEN
We examined attrition from an HIV/STD group counselling intervention in two ways: quantitative analyses of the entire sample (n=287) and structured interviews of a subset of 30 women with low attendance. In the interviews, the most common reasons for low attendance were time conflicts and enrolling primarily to obtain the monetary incentives given for completing research questionnaires. Latent class statistical analysis of the full sample identified two subgroups that differed from each other in the number of psychosocial problems recently experienced. Relative to the 'non-distressed' class, the 'distressed' class members had higher probabilities of psychological distress, low incomes, heavy substance use, sex for trade, relationship violence, and unstable housing. This group had higher HIV/STD risk, but lower intervention attendance. Members also had less education and less knowledge about HIV/STD. A higher proportion of the distressed group was African-American. Study findings suggest that in interventions for women at HIV/STD risk, it is not necessarily enough to ensure cultural relevance and to provide food, childcare, and transportation. To increase retention, interventionists should consider (1) the use of strategies to support attendance (such as monetary incentives and attention to group process factors) and (2) intervention formats that are brief, matched to participants' stage of change, population-specific, and/or maximally accessible.
Asunto(s)
Infecciones por VIH/prevención & control , Cooperación del Paciente/psicología , Consejo Sexual , Enfermedades de Transmisión Sexual/prevención & control , Adolescente , Adulto , Femenino , Infecciones por VIH/psicología , Humanos , Persona de Mediana Edad , Asunción de Riesgos , Conducta Sexual/psicología , Enfermedades de Transmisión Sexual/psicología , Factores Socioeconómicos , Trastornos Relacionados con Sustancias/complicaciones , Trastornos Relacionados con Sustancias/psicologíaRESUMEN
A review of the literature suggests that early substance initiation is related to a variety of negative outcomes, including substance misuse or abuse in adolescence and adulthood. This study examines potentially modifiable predictors of early substance initiation, including both family and peer factors known to influence early initiation. A theoretically derived model of substance initiation was tested using structural equation modeling. Results indicate that both family and peer factors have an impact on early substance initiation when children in this sample were 11 and 12 years old. The model explained 60% of the variance in substance initiation. Prosocial family processes (rules, monitoring, and attachment) had a significant impact on child peer association, decreasing involvement with antisocial peers. These prosocial family processes had a significant negative effect on substance initiation even while modeling the influence of antisocial peers. Implications for drug use prevention practice are discussed.
Asunto(s)
Familia/psicología , Grupo Paritario , Control Social Formal , Trastornos Relacionados con Sustancias/epidemiología , Trastornos Relacionados con Sustancias/psicología , Encuestas y Cuestionarios , Áreas de Influencia de Salud , Niño , Análisis Factorial , Femenino , Humanos , Masculino , Relaciones Padres-Hijo , Valor Predictivo de las Pruebas , Estudios Prospectivos , Trastornos Relacionados con Sustancias/etiología , Estados UnidosRESUMEN
Child attachment to parents has been shown in the literature to reduce the likelihood of problem behaviors through enhancing resiliency. Research examining attachment and its relationship to antisocial behavioral outcomes in adolescents has been shaped largely by social control theorists who have theorized that attachment to prosocial others inhibits the expression of antisocial behavioral outcomes (Hirschi, 1969). This paper seeks to expand the literature by investigating the development of child attachment to parent(s) during the early elementary school years as specified theoretically by the social development model (Catalano & Hawkins, 1996). Using structural equation modeling, the results support the theoretical model as proposed by the social development model. School-aged children's attachment to parents can be successfully predicted by constructs outlined in the social development model. Finally, implications for interventions that enhance child attachment to parent(s) are discussed.
Asunto(s)
Trastornos de la Conducta Infantil/prevención & control , Trastornos de la Conducta Infantil/psicología , Apego a Objetos , Relaciones Padres-Hijo , Teoría Psicológica , Psicología Infantil , Adaptación Psicológica , Adulto , Niño , Trastornos de la Conducta Infantil/etiología , Desarrollo Infantil , Escolaridad , Análisis Factorial , Humanos , Motivación , Evaluación de Necesidades , Valor Predictivo de las Pruebas , Factores de Riesgo , Socialización , Encuestas y CuestionariosRESUMEN
alpha-tubulin subunits within microtubules (MTs) can be post-translationally detyrosinated by a tubulin-specific carboxypeptidase (TCP) activity to form biochemically distinct MTs. Attempts to characterize and purify TCP have suffered from the inability to detect low levels of activity and to distinguish TCP from other, competing enzyme activities. We recently developed an assay for TCP [Webster et al. (1992) Biochemistry 31:5849] that uses taxol-stabilized MTs as the substrate. In this study, we exploited the increased sensitivity and specificity of this new assay to explore the effects of various agents that might act to either stimulate or inhibit this enzyme in vitro. We tested a variety of both monovalent and divalent cations for their ability to affect TCP, and tested whether the cations were affecting the enzyme, the substrate, or both. We found that TCP displayed salt-sensitive binding to MTs, characteristic of other, more well characterized MT-associated proteins. While both calcium and magnesium stimulated TCP activity over a narrow concentration range (2-10 mM), they inhibited activity at higher concentrations. Other divalent cations tested, including zinc, copper, and cobalt, inhibited TCP at virtually all concentrations tested, but to different levels (zinc > copper > cobalt). Most of the zinc-induced TCP inhibition was attributed to the interference with the normal binding of TCP to MTs. In addition, we examined the involvement of free sulfhydryl groups (which are important for the activities of many types of enzymes) in TCP activity by the addition of sulfhydryl-modifying compounds during the assay, and found that their addition reduced TCP activity mainly (but not solely) by their action on the extract that contained the TCP. Finally, we tested the ability of DL-benzylsuccinic acid, a potent inhibitor of carboxypeptidase A, to inhibit TCP. While carboxypeptidase A has been found, in other studies, to be inhibited by micromolar concentrations, TCP was affected only at concentrations above 20 mM, adding another proof that carboxypeptidase A and TCP are distinct enzyme activities.
Asunto(s)
Carboxipeptidasas/antagonistas & inhibidores , Cationes Bivalentes/farmacología , Cloruros/farmacología , Reactivos de Sulfhidrilo/farmacología , Animales , Encéfalo/metabolismo , Carboxipeptidasas/metabolismo , Carboxipeptidasas A , Cationes Monovalentes , Bovinos , Citoplasma/enzimología , Inhibidores Enzimáticos/farmacología , Etilmaleimida/farmacología , Concentración de Iones de Hidrógeno , Yodoacetatos/farmacología , Ácido Yodoacético , Microtúbulos/metabolismo , Sensibilidad y Especificidad , Especificidad por Sustrato , Succinatos/farmacologíaRESUMEN
Initial acquisition of social skills by high school students with mild mental retardation was measured during the social skills training game Stacking the Deck. Generalization probes were conducted outside of the training setting (immediately preceding and following training, and 6 weeks posttraining). Due to the high degree of dissimilarity between stimuli in and outside of the training setting, we hypothesized that generalization of skills to nontraining environments would be minimal. Two replications of an initial single-case study were conducted. Students demonstrated acquisition of social skills across game conditions. Immediate generalization of trained social skills did not occur. A possible "deferred generalization" effect was evidenced at 6 weeks posttraining. Results were discussed with respect to the "integrity of common stimuli" and opportunities to respond.