ABSTRACT
We explore the impact of obliquity variations on planetary habitability in hypothetical systems with high mutual inclination. We show that large-amplitude, high-frequency obliquity oscillations on Earth-like exoplanets can suppress the ice-albedo feedback, increasing the outer edge of the habitable zone. We restricted our exploration to hypothetical systems consisting of a solar-mass star, an Earth-mass planet at 1 AU, and 1 or 2 larger planets. We verified that these systems are stable for 10(8) years with N-body simulations and calculated the obliquity variations induced by the orbital evolution of the Earth-mass planet and a torque from the host star. We ran a simplified energy balance model on the terrestrial planet to assess surface temperature and ice coverage on the planet's surface, and we calculated differences in the outer edge of the habitable zone for planets with rapid obliquity variations. For each hypothetical system, we calculated the outer edge of habitability for two conditions: (1) the full evolution of the planetary spin and orbit and (2) the eccentricity and obliquity fixed at their average values. We recovered previous results that higher values of fixed obliquity and eccentricity expand the habitable zone, but we also found that obliquity oscillations further expand habitable orbits in all cases. Terrestrial planets near the outer edge of the habitable zone may be more likely to support life in systems that induce rapid obliquity oscillations as opposed to fixed-spin planets. Such planets may be the easiest to directly characterize with space-borne telescopes.
Subject(s)
Exobiology , Models, Theoretical , Planets , Climate , Energy TransferABSTRACT
Gastrointestinal stromal tumors (GISTs), also referred to as "gastrointestinal pacemaker cell tumors (GIPACT)" are mesenchymal neoplasms that are phenotypically similar to the interstitial cells of Cajal (ICC). Cytogenetic studies of this entity are rare and molecular cytogenetic studies utilizing chromosome-specific probes are nonexistent. In the current study, cytogenetic and molecular cytogenetic analysis of 12 histologically and immunohistochemically confirmed GISTs revealed loss of a whole chromosome 14 or region(s) of 14q in 8 tumors evaluated (67%) and loss of a whole chromosome 22 or region(s) of 22q in 8 (67%) patients. Loss of 14q and 22q were observed in histologically benign and malignant GISTs. Structural rearrangements of chromosome 1 were observed in 2 malignant GISTs. These findings indicate that loss of 14q and 22q are nonrandom, early events in GIST tumorigenesis and suggest that tumor suppressor genes responsible for the development of this neoplasm may be located on these chromosomal arms.
Subject(s)
Chromosome Deletion , Chromosomes, Human, Pair 14/genetics , Chromosomes, Human, Pair 22/genetics , Gastrointestinal Neoplasms/genetics , Adult , Aged , Antigens, CD34/analysis , Female , Gastrointestinal Neoplasms/metabolism , Gastrointestinal Neoplasms/pathology , Humans , Immunohistochemistry , In Situ Hybridization, Fluorescence , Karyotyping , Ki-67 Antigen/analysis , Male , Middle Aged , Proto-Oncogene Proteins c-kit/analysis , Stromal Cells/metabolism , Stromal Cells/pathologySubject(s)
Chromosomes, Human, Pair 14 , Chromosomes, Human, Pair 8 , Fibroma/genetics , Foot/pathology , Trisomy , Female , Humans , Karyotyping , Middle AgedABSTRACT
The present paper reviews the behavioral parent training literature that has focused on reducing noncompliance with developmentally delayed children. Several factors are identified which may make parental attempts to reduce developmentally delayed children's noncompliance difficult. The 13 studies reviewed are separated into group and single case approaches, and each study was assessed on a number of methodological factors. The studies generally report success in modifying non-compliance; however, the variability in the experimental rigor of the reviewed studies preclude definitive conclusions from being made at this time about the efficacy of training parents to reduce noncompliance with delayed children. As examples, only a few studies have collected parental data and home observational data. Clinical and training considerations are also discussed, such as the need to identify parental and marital characteristics that may influence training success and identify which specific training techniques are most effective in teaching parents contingency management procedures. Finally, suggestions for training parents of delayed children are offered.
Subject(s)
Cooperative Behavior , Developmental Disabilities/rehabilitation , Parents/education , Adolescent , Autistic Disorder/rehabilitation , Behavior Therapy/methods , Child , Child, Preschool , Female , Generalization, Psychological , Humans , Infant , Intellectual Disability/rehabilitation , Parents/psychology , Research DesignABSTRACT
The purpose of the present study was to compare a clinic-referred sample of developmentally delayed children to two groups of children who were not delayed: a clinic-referred sample and a nonclinic sample. Multiple outcome measures, including home observations of mother-child interactions, parental perceptions of child adjustment, and parental measures of depression and marital adjustment, were utilized. The results indicated that the delayed sample differed from the two nondelayed samples primarily in terms of emitting more maternal behavior, particularly the number of commands issued. A lower rate of compliance to total maternal commands also occurred for the delayed group. Finally, the clinic-referred delayed sample differed from the nonclinic non-delayed sample by perceiving their children as less well-adjusted. Implications of the results are discussed.
