San Diego State University

About: San Diego State University is a education organization based out in San Diego, California, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 12418 authors who have published 27950 publications receiving 1192375 citations. The organization is also known as: SDSU & San Diego State College.

Outgroup analysis and parsimony

Abstract: -Methods that use outgroups in the reconstruction of phylogeny are described and evaluated by the criterion of parsimony. By considering the character states and relationships of outgroups, one can estimate the states ancestral for a study group or ingroup, even when several character states are found among the outgroups. Algorithms and rules are presented that find the most parsimonious estimates of ancestral states for binary and multistate characters when outgroup relationships are well resolved. Other rules indicate the extent to which uincertainty about outgroup relationships leads to uncertainty about the ancestral states. The algorithms and rules are based on "simple parsimony" in that convergences and reversals are counted equally. After parsimony is measured locally among the outgroups to estimate ancestral states, parsimony is measured locally within the ingroup, given the ancestral states, to find the ingroup cladogram. This two-step procedure is shown to find the ingroup cladograms that are most parsimonious globally; that is, most parsimonious when parsimony is measured simultaneously over the ingroup and outgroups. However, the two-step procedure is guaranteed to achieve global parsimony only when: (a) outgroup relationships are sufficiently resolved beforehand; (b) outgroup analysis is taken to indicate the state not in the most recent common ancestor of the ingroup, but in a more distant ancestor; and (c) ancestral states are considered while the ingroup is being resolved, not merely added afterward to root an unrooted network. The criterion of global parsimony is then applied to evaluate procedures used when outgroup relationships are poorly resolved. The procedure that chooses as ancestral the state occurring most commonly among the outgroups can sometimes yield cladograms that are not globally parsimonious. By the criterion of global parsimony, the best procedure is one that simultaneously resolves the outgroups and ingroup with the data at hand. Finally, simple parsimony can choose among competing hypotheses, but it often fails to indicate how much confidence can be placed in that choice. [Phylogeny reconstruction; cladistic methods; outgroup analysis; character polarity; parsimony.] This paper explores the use of outgroup analysis in phylogeny reconstruction. When reconstructing a phylogeny, a systematist asks: Given a group of organisms (the ingroup), what are the monophyletic subgroups? If the members of a subgroup share a character state that is derived within the group, the monophyly of this subgroup is corroborated (Hennig, 1966; Wiley, 1975). Hence, systematists attempting to infer phylogenies have sought methods for determining whether a given character state is derived (apomorphic) or ancestral (plesiomorphic). Many methods for assessing the evolutionary polarity of characters have been proposed, including outgroup analysis, ingroup analysis, the ontogenetic method, and the paleontological method. These approaches have been reviewed recently by Crisci and Stuessy (1980), de Jong (1980), Stevens (1980), Arnold (1981), Nelson and Platnick (1981), and others. The methods perhaps most widely accepted today are outgroup analysis and the ontogenetic method, the relative merits of which are still being debated (contrast Nelson [1978] and Patterson [1982] with Lundberg [1973], Wheeler [1981] and Voorzanger and van der Steen [1982]). In its simplest form, outgroup analysis can be summarized by the following rule (Watrous and Wheeler, 1981): For a given character with two or more states within a group, the state occurring in related groups is assumed to be the plesiomorphic state. This rule is inadequate, however, when characters vary among the related groups (the outgroups). Arnold (1981) and Farris (1982) have dealt with some cases of

Understanding the association between socioeconomic status and physical health: do negative emotions play a role?

Abstract: In this article, the authors evaluate the possible roles of negative emotions and cognitions in the association between socioeconomic status (SES) and physical health, focusing on the outcomes of cardiovascular diseases and all-cause mortality. After reviewing the limited direct evidence, the authors examine indirect evidence showing that (a) SES relates to the targeted health outcomes, (b) SES relates to negative emotions and cognitions, and (c) negative emotions and cognitions relate to the targeted health outcomes. The authors present a general framework for understanding the roles of cognitive-emotional factors, suggesting that low-SES environments are stressful and reduce individuals' reserve capacity to manage stress, thereby increasing vulnerability to negative emotions and cognitions. The article concludes with suggestions for future research to better evaluate the proposed model.

Diversity and distribution of coral-associated bacteria

Abstract: Coral reefs are the most biodiverse of all marine ecosystems; however, very little is known about prokaryotic diversity in these systems. To address this issue, we sequenced over 1000 bacterial 16S rDNAs from 3 massive coral species (Montastraea franksi, Diploria strigosa, and Porites astreoides) in Panama and Bermuda. Analysis of only 14 coral samples yielded 430 distinct bacterial ribotypes. Statistical analyses suggest that additional sequencing would have resulted in a total of 6000 bacterial ribotypes. Half of the sequences shared <93% identity to previously published 16S sequences, and therefore probably represent novel bacterial genera and species; this degree of novelty was substantially higher than that observed for other marine samples. Samples from the Panama corals were more diverse than those from Bermuda, paralleling diversity gradients seen in metazoans. The coral-bacteria associations were non-random. Different coral species had distinct bacterial communities, even when physically adjacent, while bacterial communities from the same coral species separated by time (~1 yr) or space (3000 km) were similar. Analysis of the branching coral Porites furcata showed that bacterial ribotypes can also be structured spatially within colonies. Therefore, corals and reefs represent landscapes of diverse, ecologically structured prokaryotic communities.

Mental health need and access to mental health services by youths involved with child welfare: a national survey.

Abstract: Objective This study assessed the relationship between the need for and use of mental health services among a nationally representative sample of children who were investigated by child welfare agencies after reported maltreatment. Method Data were collected at study entry into the National Survey of Child and Adolescent Well-Being and were weighted to provide population estimates. Results Nearly half (47.9%) of the youths aged 2 to 14 years ( N = 3,803) with completed child welfare investigations had clinically significant emotional or behavioral problems. Youths with mental health need (defined by a clinical range score on the Child Behavior Checklist) were much more likely to receive mental health services than lower scoring youth; still, only one fourth of such youths received any specialty mental health care during the previous 12 months. Clinical need was related to receipt of mental health care across all age groups (odds ratio=2.7–3.5). In addition, for young children (2–5 years), sexual abuse (versus neglect) increased access to mental health services. For latency-age youths, African-American race and living at home significantly reduced the likelihood of care. Adolescents living at home were also less likely to receive services, whereas having a parent with severe mental illness increased (odds ratio=2.4) the likelihood of service use. Conclusions Routine screening for mental health need and increasing access to mental health professionals for further evaluation and treatment should be a priority for children early in their contact with the child welfare system.

Leadership and Procedural Justice Climate as Antecedents of Unit-Level Organizational Citizenship Behavior.

Abstract: Despite an abundance of research conducted on organizational citizenship behavior (OCB) at the individual level of analysis, relatively little is known about unit-level OCB. To investigate the antecedents of unit-level OCB, data were collected from employees of 249 grocery store departments. Structural equation modeling techniques were used to test a model in which procedural justice climate was hypothesized to partially mediate the relationship between leadership behavior (servant-leadership) and unit-level OCB. Models were tested using both employee ratings and manager ratings of unit-level OCB. The results gave general support for the hypotheses, although there were some differences depending on the source of the OCB ratings (supervisor or subordinate), whether the type of department was controlled for, and whether a common method variance factor was included. Overall, the evidence generally supported the association of both servant-leadership and procedural justice climate with unit-level OCB. Building on the current study, a multilevel framework for the study of OCB is presented in conjunction with a discussion of future research directions in four specific areas.