System Dynamics Modeling for Cancer Prevention and Control: A systematic review

Cancer prevention and control requires consideration of complex interactions between multilevel factors. System dynamics modeling, which consists of diagramming and simulation approaches for understanding and managing such complexity, is being increasingly applied to cancer prevention and control, but the breadth, characteristics, and quality of these studies is not known. We searched PubMed, Scopus, APA PsycInfo, and eight peer-reviewed journals to identify cancer-related studies that used system dynamics modeling. A dual review process was used to determine eligibility. Included studies were assessed using quality criteria adapted from prior literature and mapped onto the cancer control continuum. Characteristics of studies and models were abstracted and qualitatively synthesized. 32 studies met our inclusion criteria. A mix of simulation and diagramming approaches were used to address diverse topics, including chemotherapy treatments (16%), interventions to reduce tobacco or e-cigarettes use (16%), and cancer risk from environmental contamination (13%). Models spanned all focus areas of the cancer control continuum, with treatment (44%), prevention (34%), and detection (31%) being the most common. The quality assessment of studies was low, particularly for simulation approaches. Diagramming-only studies more often used participatory approaches. Involvement of participants, description of model development processes, and proper calibration and validation of models showed the greatest room for improvement. System dynamics modeling can illustrate complex interactions and help identify potential interventions across the cancer control continuum. Prior efforts have been hampered by a lack of rigor and transparency regarding model development and testing. Supportive infrastructure for increasing awareness, accessibility, and further development of best practices of system dynamics for multidisciplinary cancer research is needed

The attrition rate of licensed chiropractors in California: an exploratory ecological investigation of time-trend data

<p>Abstract</p> <p>Background</p> <p>The authors hypothesized the attrition rate of licensed chiropractors in California has gradually increased over the past several decades. "Attrition" as determined for this study is defined as a loss of legal authority to practice chiropractic for any reason during the first 10 years after the license was issued. The percentage of license attrition after 10 years was determined for each group of graduates licensed in California each year between 1970 and 1998. The cost of tuition, the increase in the supply of licensed chiropractors and the ratio of licensed chiropractors to California residents were examined as possible influences on the rate of license attrition.</p> <p>Methods</p> <p>The attrition rate was determined by a retrospective analysis of license status data obtained from the California Department of Consumer Affairs. Other variables were determined from US Bureau of Census data, survey data from the American Chiropractic Association and catalogs from a US chiropractic college.</p> <p>Results</p> <p>The 10-year attrition rate rose from 10% for those graduates licensed in 1970 to a peak of 27.8% in 1991. The 10-year attrition rate has since remained between 20-25% for the doctors licensed between 1992-1998.</p> <p>Conclusions</p> <p>Available evidence supports the hypothesis that the attrition rate for licensed chiropractors in the first 10 years of practice has risen in the past several decades.</p

A preparative, spectroscopic and equilibrium study of some phenyl-2-thiazoline fluorophores for aluminium(III) detection

Copyright © 2000 The Royal Society of Chemistry and the Centre National de la Recherche ScientifiqueAs part of a study of fluorophores for selective Al3+ detection and of potential use in the study of intracellular Al³⁺, the preparative, UV–visible and fluorescence spectroscopic, and Al³⁺ coordination characteristics of five ligands containing the conjugated phenolic substituted thiazoline chromophore of the natural siderophore, pyochelin, 2-[2-(2-hydroxyphenyl)-4,5-dihydro-1,3-thiazol-4-yl]-3-methyl-1,3-thiazolane-4-carboxylic acid) 1, are reported. The five ligands are 2-(2-hydroxyphenyl)-4,5-dihydro-1,3-thiazole-4-carboxylic acid, 2, 2-(4,5-dihydro-1,3-thiazol-2-yl)phenol, 3, 4-bromo-2-(4,5-dihydro-1,3-thiazol-2-yl)phenol, 4, 2-(4,5-dihydro-1,3-thiazol-2-yl)-5-nitrophenol, 5, and 2-(4,5-dihydro-1,3-thiazol-2-yl)-4-nitrophenol, 6. All form stable binary Al³⁺ complexes in 75% methanol and 25% water in the case of 2, and 73.2% methanol, 24.4% water and 2.4%N,N-dimethylformamide in the case of 3–6, and exhibit substantial UV–visible absorbance changes on coordination. However, while 2, 3 and 4 fluoresce strongly when coordinated to Al³⁺, 5 and 6 do not, probably because their fluorescence is quenched through a twisted intramolecular charge transfer process. All five ligands show selectivity in complexing for Al³⁺ over other metal ions and, in the case of 2, 3 and 4, represent an initial stage in the development of Al³⁺ specific fluorophores for biological use.Stephanie G. Lambert, Jo-Anne M. Taylor, Kate L. Wegener, Susan L. Woodhouse, Stephen F. Lincoln and A. David War