A simplification of a result by zellini on the maximal rank of symmetric three-way arrays

Zellini (1979, Theorem 3.1) has shown how to decompose an arbitrary symmetric matrix of ordern ×n as a linear combination of 1/2n(n+1) fixed rank one matrices, thus constructing an explicit tensor basis for the set of symmetricn ×n matrices. Zellini's decomposition is based on properties of persymmetric matrices. In the present paper, a simplified tensor basis is given, by showing that a symmetric matrix can also be decomposed in terms of 1/2n(n+1) fixed binary matrices of rank one. The decomposition implies that ann ×n ×p array consisting ofp symmetricn ×n slabs has maximal rank 1/2n(n+1). Likewise, an unconstrained INDSCAL (symmetric CANDECOMP/PARAFAC) decomposition of such an array will yield a perfect fit in 1/2n(n+1) dimensions. When the fitting only pertains to the off-diagonal elements of the symmetric matrices, as is the case in a version of PARAFAC where communalities are involved, the maximal number of dimensions can be further reduced to 1/2n(n–1). However, when the saliences in INDSCAL are constrained to be nonnegative, the tensor basis result does not apply. In fact, it is shown that in this case the number of dimensions needed can be as large asp, the number of matrices analyzed.     

Temporal discrimination learning of operant feeding in goldfish (Carassius auratus)

Operant temporal discrimination learning was investigated in goldfish. In the first experiment, there was a fixed daily change in illumination. Eight subjects were trained to operate a lever that reinforced each press with food. The period during which responses were reinforced was then progressively reduced until it was 1 hr in every 24. The final 1-hr feeding schedule was maintained over 4 weeks. The feeding period commenced at the same time each day throughout. The food dispensers were then made inactive, and a period of extinction ensued for 6 days. The pattern of responding suggested that the fish were able to exhibit temporal discrimination in anticipation of feeding time. This pattern of responding persisted for a limited number of days during the extinction procedure. The second experiment produced evidence that operant temporal discrimination could develop under continuous illumination.     

Exchange delays and impulsive choice in adult humans.

Choice responding by adult humans in a discrete-trial task was examined as a function of conditions that manipulated either the delay to point delivery or the delay between points and their exchange for money. In point-delay conditions, subjects chose between an "impulsive" alternative that provided a small amount of points immediately and a "self-control" alternative that provided a larger amount of points delayed by 15, 30, or 60 s. Points were exchanged for money immediately following the session. Subjects preferred the self-control alternative. In exchange-delay conditions, subjects chose between a small amount of points exchangeable for money immediately following the session and a larger amount of points exchangeable for money after 1 day, 3 weeks, or 6 weeks. A self-control preference observed for all subjects in the 1-day exchange-delay condition reversed to exclusive impulsive preference for 4 of the 6 subjects when choice conditions involved exchange delays of 3 or 6 weeks. These results show that human choice is sensitive to the manipulation of exchange delays and that impulsive preference can be obtained with exchange delays on the order of weeks.     

Cut-free sequent and tableau systems for propositional Diodorean modal logics

We present sound, (weakly) complete and cut-free tableau systems for the propositional normal modal logicsS4.3, S4.3.1 andS4.14. When the modality is given a temporal interpretation, these logics respectively model time as a linear dense sequence of points; as a linear discrete sequence of points; and as a branching tree where each branch is a linear discrete sequence of points.Although cut-free, the last two systems do not possess the subformula property. But for any given finite set of formulaeX the superformulae involved are always bounded by a finite set of formulaeX* _L depending only onX and the logicL. Thus each system gives a nondeterministic decision procedure for the logic in question. The completeness proofs yield deterministic decision procedures for each logic because each proof is constructive.Each tableau system has a cut-free sequent analogue proving that Gentzen's cut-elimination theorem holds for these latter systems. The techniques are due to Hintikka and Rautenberg.Presented byDov M. Gabbay     

Functions of the environment in behavioral evolution

This paper explores some of the ways in which the environment functions with respect to behavior within an explanatory framework analogous to that of evolutionary biology. In both the behavioral and organic domains, the environment functions differently with respect to individual occurrences and evolutionary units. Within the behavioral domain, the problem of accounting for an occurrence of an operant instance differs from that of accounting for the existence of the operant unit of which the instance is a part. Maintaining these distinctions in levels of analysis within the behavioral domain, we focus first on operant units and operant instances as products of evolutionary processes occurring in the behavioral domain and second upon the causal role of the environment with respect to the existence of operant units and the occurrence of operant instances. The environment's function is selective with respect to origin, maintenance, suppression, and extinction of behavioral populations. At the level of operant instances, the environment has instantiating functions-evocative or alterative. Evocative functions are exemplified by discriminative relations, and alterative functions include both conditional and motivative relations. Implications are considered regarding extension of the analogy to more complex behavior-environment relations.     

U.S.- and Mexico-born Hispanic teen mothers: a descriptive study of factors that relate to postpartum compliance

Compliance with postpartum visits after teenage births in the US was examined among 289 Hispanic teenagers, of whom 127 were born in Mexico or border towns, who delivered at Harris County Hospital District and scheduled postpartum appointments at the Teen Health Clinic. The mean age was 17.31 years for mothers and 21.95 years for fathers. 56.7% (164) were married. 49.8% lived with husbands, 25.8% with parents, 22.3% with friends/relatives, and 2.1% alone. 74.7% stated that they had no social supports. 88.9% had a term delivery, 8.3% a preterm delivery, and 2.8% a fetal loss. 67.5% were first births, 5.5% had a previous abortion, and 3.1% had a previous miscarriage. 23.2% had a previous child, and 0.7% had a previous preterm delivery. Some form of prenatal care was received by 85.1%. 34.3% reported no further educational plans. 17.3% (50) returned for a scheduled postpartum visit. Mothers with a prior history of a premature birth or miscarriage were more likely to return postpartum compared to mothers with a first or prior birth. The differences are marginally significant. None of the mothers with a prior abortion returned. 34.9% of the returning teen mothers were more likely to have had prenatal care. Returning mothers also were a larger percentage of those with no future educational plans. 13.4% of returning mothers had an available social support system. Country of origin was not associated with support systems, prenatal care, return status, educational plans, pregnancy history, or current birth outcome. Out of the 50 returning, 20 were Mexican-born and married. Only Mexican marital status was found to be a significant variable explaining differences. Marital status had no effect on the 26 US native-born returnees. 92% of the Mexican-born teens were married and had a support system. The most dramatic feature of this study is the high level of noncompliance among both US-born and Mexican-born adolescents. There were few distinguishing features between these two groups. Return status was affected by very few features and was achieved by a very small percentage of the study population. The suggestion is made that poverty, a lack of health insurance, and poor knowledge of English, as representative of cultural dissimilarity, may be responsible for poor use of preventive care.     

Assessing Multicultural Counseling Competence: A Review of Instrumentation

The authors review four new instruments designed to assess multicultural counseling competence in trainees and practicing professionals. The Cross-Cultural Counseling Inventory—Revised (CCCI-R), the Multicultural Counseling Awareness Scale—Form B (MCAS:B), the Multicultural Counseling Inventory (MCI), and the Multicultural Awareness-Knowledge-and Skills Survey (MAKSS) were each critically reviewed in terms of item development, psychometric properties, and pragmatic utility. Specific research suggestions for continued empirical validation on the instruments are posited, and strong cautions regarding their current use in training are leveled.     

The Role of an Academic Department in Promoting Faculty Development: Recognizing Diversity and Leading to Excellence

The authors discuss the role of an academic department in promoting faculty development. Specifically, the authors (a) define faculty development from a departmental perspective, (b) discuss stages and seasons in academic careers, and (c) delineate specific faculty development goals and programs within the department.