Alex Velicer Senior Art Portfolio

https://digitalcommons.snc.edu/artportfolios/1004/thumbnail.jp

Detecting longitudinal patterns of daily smoking following drastic cigarette reduction

To enhance prolonged smoking cessation or reduction, a better understanding of the process of change is needed. This study examines daily smoking rates following the end of an intensive smoking reduction program originally designed to evaluate the relationship of tobacco biomarkers with reduced levels of smoking. A novel pattern-oriented approach called time series-based typology is used to detect homogeneous smoking patterns in time-intensively (i.e., 40 occasions) observed smokers (n = 57), who were predominantly Caucasian (94.7%), male (52.6%), and on average 47.9 years old (SD = 11.3). The majority of the smokers exhibited a change in their daily smoking behavior over the course of 40 days with 47.4% increasing and 40.4% decreasing the number of cigarettes smoked per day, which is contrary to the results a group level approach would have found. Very few smokers (12.3%) maintained their average smoking rate, and exhibited an externally controlled smoking pattern. Trajectory type could be predicted by temporally proximal motivation and self-efficacy variables ((F(4, 106) =3.46, p = .011, η2 = .115), underscoring their importance in maintaining reduced smoking rates. Time series-based typology demonstrated good sensitivity to the identification of meaningfully different trajectories

Comparing Visual and Statistical Analysis in Single-Case Studies Using Published Studies

Little is known about the extent to which interrupted time-series analysis (ITSA) can be applied to short, single-case study designs and whether those applications produce results consistent with visual analysis (VA). This paper examines the extent to which ITSA can be applied to single-case study designs and compares the results based on two methods: ITSA and VA, using papers published in the Journal of Applied Behavior Analysis in 2010. The study was made possible by the development of software called UnGraph® which facilitates the recovery of raw data from the graphs. ITSA was successfully applied to 94% of the examined graphs with the number of observations ranging from 8 to 136. Moderate to high lag 1 autocorrelations (\u3e .50) were found for 46% of the data series. Effect sizes similar to group-level Cohen’s d were identified based on the tertile distribution. Effects ranging from 0.00 to 0.99 were classified as small, those ranging from 1.00 to 2.49 as medium, and large effect sizes were defined as 2.50 or greater. Comparison of the conclusions from VA and ITSA had a low level of agreement (Kappa = .14, accounting for the agreement expected by chance). The results demonstrate that ITSA can be broadly implemented in applied behavior analysis research. These two methods should be viewed as complimentary and used concurrently

The Marek's disease virus (MDV) unique short region: Alphaherpesvirus-homologous,fowlpox virus-homologous, and MDV-specific genes

AbstractDespite its previous classification as a gammaherpesvinus, primarily due to its lymphotropism, Marek's disease virus (MDV), an oncogenic avian herpesvirus, is phylogenetically more related to the “neurotropic” alphaherpesviruses, characterized by its prototype, herpes simplex virus (HSV) (Buckmaster et al., 1988, J. Gen. Virol. 69, 2033–2042). In this report we present the DNA sequence of an 11,286-bp DNA segment encompassing the entire 11,160-by-long Us region of the oncogenic avian herpesvirus, Marek's disease virus. Eleven open reading frames (ORFs) likely to code for proteins were identified; of these, 7 represent homologs exclusive to alphaherpesvirus S component genes. These include MDV counterparts of HSV US1 (ICP22), US2, US3 (a serine-threonine protein kinase), US6, US7, and US8 (HSV glycoproteins gD, gl, and gE, respectively), and US10. Three additional ORFs were identified with no apparent relation to any sequences currently present in the SwissProt or GenBank/EMBL databases, while a fourth was found to exhibit significant homology to an uncharacterized fowlpox virus (FPV) ORF. Having precisely identified the IRS-Us and Us- TRs junctions, we have corrected and clarified their previously reported locations. By characterizing genes encoding three new alphaherpesvirus-related homologs (US1, US8, and US10), completing the sequence for a fourth (US7), and identifying 2 new MDV-specific ORFs (SORF1 and SORF3) and a fowlpox homolog (SORF2), our sequence analysis of the “virulent” GA strain of MDV (vMDV) extends upon that of a 5255-bp segment located in the Us region of the “very virulent” RB1 B strain of MDV (vvMDV) (Ross et al., 1991, J. Gen. Virol. 72, 939–947; 949–954). These two sequences were found to exhibit 99% identity at both nucleotide and predicted amino acid levels. Combined with the fact that MDV Us sequences failed to show statistically significant CpG deficiencies, our analysis is consistent with MDV bearing a closer phylogenetic relation to alphaherpesviruses than to gammaherpesviruses. Because alpha herpesvirus-specific Us region genes are primarily nonessential for virus replication, they are thought to be important biological property determinants. Thus, our sequence provides a foundation for further MDV studies aimed at resolving the apparent discrepancy between MDV's genetic and biologic properties

Cluster subtypes appropriate for preventing postpartum smoking relapse

Objective: While the majority of women quit smoking either before or during pregnancy, 60 to 80% relapse in the postpartum period. The objective of this research was to examine postpartum women who quit smoking during their pregnancies and to determine the predictive factors for relapse in the postpartum period by identifying different subgroups that predict risk of relapse. Method: One hundred forty four postpartum women who were abstinent at the time of delivery were recruited. Data regarding the Acquisition Stage of Change, Decisional Balance and Situational Temptations to Smoke were assessed in the immediate postpartum period. Based on their intention to remain abstinent, 121 women identified in the acquisition-Precontemplation (aPC) group comprised the study sample. Smoking status was assessed again at 2 months postpartum. Results: A cluster analysis was performed to idenitfy subgroups of the acquisition-Precontemplation (aPC) group. Four subgroups were identified and were labeled Most Protected, Ambivalent, Risk Denial, and High Risk. Logistic regression was performed to establish external validity of the clusters. The clusters and exclusive breastfeeding were the only statistically significant variables associated with relapse at 2 months postpartum. Conclusions: The results confirmed the clusters identified in previous prevention research with both adolescents and postpartum women, The cluster profiles can serve to guide the development of a tailored intervention program

Typology of alcohol users based on longitudinal patterns of drinking

Objective: Worldwide, alcohol is the most commonly used psychoactive substance. However, heterogeneity among alcohol users has been widely recognized. This paper presents a typology of alcohol users based on an implementation of idiographic methodology to examine longitudinal daily and cyclic (weekly) patterns of alcohol use at the individual level. Method: A secondary data analysis was performed on the pre-intervention data from a large randomized control trial. A time series analysis was performed at the individual level, and a dynamic cluster analysis was employed to identify homogenous longitudinal patterns of drinking behavior at the group level. The analysis employed 180 daily observations of alcohol use in a sample of 177 alcohol users. Results: The first order autocorrelations ranged from − .76 to .72, and seventh order autocorrelations ranged from − .27 to .79. Eight distinct profiles of alcohol users were identified, each characterized by a unique configuration of first and seventh autoregressive terms and longitudinal trajectories of alcohol use. External validity of the profiles confirmed the theoretical relevance of different patterns of alcohol use. Significant differences among the eight subtypes were found on gender, marital status, frequency of drug use, lifetime alcohol dependence, family history of alcohol use and the Short Index of Problems. Conclusions: Our findings demonstrate that individuals can have very different temporal patterns of drinking behavior. The daily and cyclic patterns of alcohol use may be important for designing tailored interventions for problem drinkers

Exploitative and Hierarchical Antagonism in a Cooperative Bacterium

Social organisms that cooperate with some members of their own species, such as close relatives, may fail to cooperate with other genotypes of the same species. Such noncooperation may take the form of outright antagonism or social exploitation. Myxococcus xanthus is a highly social prokaryote that cooperatively develops into spore-bearing, multicellular fruiting bodies in response to starvation. Here we have characterized the nature of social interactions among nine developmentally proficient strains of M. xanthus isolated from spatially distant locations. Strains were competed against one another in all possible pairwise combinations during starvation-induced development. In most pairings, at least one competitor exhibited strong antagonism toward its partner and a majority of mixes showed bidirectional antagonism that decreased total spore production, even to the point of driving whole populations to extinction. Differential response to mixing was the primary determinant of competitive superiority rather than the sporulation efficiencies of unmixed populations. In some competitive pairings, the dominant partner sporulated more efficiently in mixed populations than in clonal isolation. This finding represents a novel form of exploitation in bacteria carried out by socially competent genotypes and is the first documentation of social exploitation among natural bacterial isolates. Patterns of antagonistic superiority among these strains form a highly linear dominance hierarchy. At least some competition pairs construct chimeric, rather than segregated, fruiting bodies. The cooperative prokaryote M. xanthus has diverged into a large number of distinct social types that cooperate with clone-mates but exhibit intense antagonism toward distinct social types of the same species. Most lengthy migration events in nature may thus result in strong antagonism between migratory and resident populations, and this antagonism may have large effects on local population sizes and dynamics. Intense mutual antagonism appears to be more prevalent in this prokaryotic social species than has been observed in the eukaryotic social slime mold Dictyostelium discoideum, which also exhibits multicellular development. The finding of several cases of facultative social exploitation among these natural isolates suggests that such exploitation may occur frequently in nature in many prokaryotes with cooperative traits

Algae for biofuel:will the evolution of weeds limit the enterprise?

Algae hold promise as a source of biofuel. Yet the manner in which algae are most efficiently propagated and harvested is different from that used in traditional agriculture. In theory, algae can be grown in continuous culture and harvested frequently to maintain high yields with a short turnaround time. However, the maintenance of the population in a state of continuous growth will likely impose selection for fast growth, possibly opposing the maintenance of lipid stores desiriable for fuel. Any harvesting that removes a subset of the population and leaves the survivors to establish the next generation may quickly select traits that escape harvesting. An understanding of these problems should help identify methods for retarding the evolution and enhancing biofuel production

Mediation analysis of decisional balance, sun avoidance and sunscreen use in the precontemplation and preparation stages for sun protection

Objective: Mediation analyses of sun protection were conducted testing structural equation models using longitudinal data with three waves. An effect was said to be mediated if the standardised path between processes of change, decisional balance and sun protection outcomes was significant. Design: Longitudinal models of sun protection using data from individuals in the precontemplation (N = 964) and preparation (N = 463) stages who participated of an expert system intervention. Main outcome measures: Nine processes of change for sun protection, decisional balance constructs of sun protection (pros and cons), sun avoidance behaviour and sunscreen use. Results: With the exception of two processes in the preparation stage, processes of change predicted the pros (r = .126–.614), and the pros predicted the outcomes (r = .181–.272). Three models with the cons as mediator in the preparation stage, and none in the precontemplation stage, showed a mediated relationship between processes and outcomes. Conclusion: In general, mediation analyses found both the process of change-to-pros and pros-to-behaviour paths significant for both precontemplation and preparation stages, and for both sun avoidance and sunscreen use outcomes. Findings provide support for the importance of assessing the role of underlying risk cognitions in improving sun protection adherence

Contraceptive and Condom Use Adoption and Maintenance: A Stage Paradigm Approach

The Transtheoretical Model of Behavior Change was examined for its applicability to contraceptive and condom use adoption and maintenance using N = 248 heterosexually active college-age men and women. The model posits that individuals do not go directly from old behaviors to new behaviors, but progress through a sequence of stages: precontemplation, contemplation, preparation, action, and maintenance. The stages of change offer a temporal dimension that provides information regarding when a particular shift in attitudes, intentions, and behavior may occur. The model also postulates a set of constructs that act as sensitive intervening or outcome variables—the pros and cons of change and self-efficacy. The results demonstrated that individuals were furthest along in the stages of change for general contraceptive use, followed closely by condom use with other (e.g., casual) partners, and then condom use with main partners. Although no sex differences were found for the stages for the three separate contraceptive behaviors, males and females differed on the pros and cons and levels of self-efficacy when engaging in intercourse with the two types of partners. MANOVA/ANOVA results indicated that the relationship between stages and other constructs follows predicted patterns suggesting that the transtheoretical model may provide a useful framework or paradigm for understanding contraceptive and condom use behavior