A systematic review of peer-reviewed, empirical literature published between 1990 and 2006 was undertaken to determine whether existing research could provide evidence, and a deeper understanding of the relationship between dropping out of high school and the use of substances such as tobacco, alcohol, cannabis/marijuana and other illicit drugs. Forty-six articles were reviewed. The review describes the heterogeneity of theoretical frameworks employed, as well as the limited ability of any one to adequately explain the relationship between high school dropout and substance use. A refinement of the many confounding and mediating variables into coherent conceptual categories would aid more robust theory building and theory integration. In spite of differences in dropout definitions and diverse measures of substance use across studies, the main findings point to a largely consistent relationship between dropping out of high school and substance use. However, socially disadvantaged and poor persons, dropouts, and drug users are over-represented in some of the loss to follow-up groups in longitudinal studies surveyed. More rigorous mechanisms to retain participants in longitudinal studies should be employed. Suggestions for future research include comparisons between urban and rural populations, employing qualitative research methods, and research in developing countries, which have the least favourable school outcomes and a dearth of research on high school dropout.

OBJECTIVE—This study examined 1) whether the benefits of mothers’ and fathers’ accepting relationships with their adolescents regarding diabetes control were due to parental monitoring and 2) how parents together may provide sufficient acceptance and monitoring for diabetes management. RESEARCH DESIGN AND METHODS—Adolescents aged 10–14 years with type 1 diabetes (n = 185) and their mothers (n = 185) and fathers (n = 145) completed assessments of parental acceptance and monitoring of diabetes tasks. Adolescents completed a modified version of the Self-Care Inventory (1) to measure adherence. A1C scores were used as a marker of glycemic control. RESULTS—Mediational analyses revealed that the benefits of adolescents’ reports of fathers’ acceptance on A1C and mothers’ and fathers’ acceptance on better adherence were partially mediated by monitoring. Both mothers’ and fathers’ monitoring and fathers’ acceptance had independent effects in predicting adherence. However, only fathers’ monitoring had an independent effect on A1C. The effect of fathers’ monitoring on A1C occurred as fathers were monitoring at a lower level than mothers. Mothers’ and fathers’ reports of their own acceptance and monitoring were not associated with A1C or adherence. CONCLUSIONS—Results reveal the importance of fathers’ acceptance and monitoring in diabetes management, a role that should be encouraged, despite the little attention it has received.

Summary A mathematical formulation, applicable to both numerical simulation and transient well analysis, that describes the flow of gas in very tight (k8<0.1md) porous media and includes a dual-mechanism transport of gas is developed. Gas is assumed to be traveling under the influence of a concentration field and a pressure field. Transport through the concentration field is a Knudsen flow process and is modeled with Fick's law of diffusion. Transport through the pressure field is a laminar process and is modeled with Darcy's law (inertial/turbulent effects are ignored). The combination of these two flow mechanisms rigorously yields a composition-, pressure-, and saturation-dependent slippage factor. The pressure dependence arises from treating the gas as a real gas. The derived dynamic slippage is most applicable in reservoirs with permeabilities 0.01 md. The results indicate that in reservoirs of this type, differences between recoveries after 10 years of production with the dynamic-slip and constant-slip approaches were as great as 10%, depending on the initial gas saturation. If an economic production rate is considered, differences as great as 30% can be expected. Introduction lt has been estimated that 400 to 1,000 Tcf [11l.3×1012 to 28.3×1012 m3] of natural gas are trapped in formations designated as "tight sands" (k8<0.1 md). Also, another 300 to 2,700 Tcf [8.5×1012 to 76.5×1012 m3] of natural gas may be trapped in other low-permeability formations, such as Devonian shales and coal seams. The application of Darcy's law to gas flow in these low-permeability formations requires a correction for the Klinkenberg effect (gas slippage across the capillary walls of the pore channels). This correction takes the form of a slippage factor, b, in the Klinkenberg equation:Equation 1 Klinkenberg2 made the following observations:Fig. 1, 2, and 3** show that the apparent permeability is approximately a linear function of the reciprocal mean pressure. This linear function, however, is an approximation, as becomes evident from Tables 5, 6, and 7*** wherein the value of constant b increases with increasing pressure.Even with an idealized pore system, the factor b cannot be expected to be constant, as the theory of Kundt and Warburg cannot be applied to the flow of gas through a capillary if the mean free path is no longer small compared with the radius of the capillary (i.e., deviations to be expected at reduced pressures).This change in the factor b however, will not be discussed here in detail. Rose3 and, more recently, Sampath and Keighin4 conducted gas flow experiments in cores partially saturated with water. Their results show that the slope of the line ka vs. 1/p (i.e., the slippage effect) decreases with increasing water saturation. During depletion, a gas reservoir undergoes changes (both in time and location) in pressure and saturation. The effect of slippage, therefore, varies throughout the life of the reservoir. To date, no detailed theoretical or experimental investigation has been conducted regarding the dynamic behavior of gas slippage. This is surprising because of the large reserves of gas trapped in tight formations. We have developed a dynamic slippage model that is similar to the approach of Adzumi5 for slip through capillary tubes. This approach, based on simultaneous flow resulting from viscous (Darcian) and diffusion (Fickian) flow processes, yields a pressure-, composition-, and saturation-dependent slippage factor. In this way, it is possible to build the time- and space-dependent character of the slippage phenomenon into the gas-transport equation in porous media.

Certain groups in the United States remain at high risk and suffer disproportionately from tobacco-related illness and death despite progress made in reducing tobacco use. To address gaps in research on tobacco-related disparities and develop a comprehensive agenda aimed at reducing such disparities, representatives from funding agencies, community-based organizations, and academic institutions convened at the National Conference on Tobacco and Health Disparities in 2002. Conference participants reviewed the current research, identified existing gaps, and prioritized scientific recommendations. Panel discussions were organized to address research areas affecting underserved and understudied populations. We report major research recommendations made by the conference participants in several scientific domains. These recommendations will ultimately help guide the field in reducing and eliminating tobacco-related disparities in the United States.