Common methodological problems in MMPI research.

Indicates that research with the MMPI continues at a high rate and suggests that too many articles submitted and even accepted for publication are methodologically weak. This article discusses some common methodological problems involving the use of the MMPI that were encountered in the course of reviewing articles submitted for publication. These problems involve the use of the MMPI as an all-purpose measure sensitive to "normal range" personality attributes, scale proliferation, limited-validity short forms, errors in assessing profile change, and erroneous interpretations of group data. Some suggestions for improving research designs are made. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermodynamic properties of the benzene and n-heptane system at elevated temperatures

The total vapour pressure and the composition of the liquid and vapour phases of the benzene and n-heptane system have been experimentally determined under equilibrium conditions at 110, 125, 140, 155, 170, 185, 200 and 215 °C. The corresponding composition of the vapour phase was also estimated using an expression for the liquid phase activity coefficient as a function of the composition of the liquid phase. Several expressions were compared and it has been found that the three-constant Redlich and Kister equation gave the best fit of the experimental vapour pressure data than the other equations. Comparison between the calculated and measured vapour compositions has shown a discrepancy of y_meas,—y_calc. of the order of 0.02 mol fraction or 10 times the experimental tolerance. Nevertheless, the experimental values were reasonably thermodynamically consistent. The low values of the liquid phase activity coefficients indicated that the behaviour of this particular system was not far from ideality. Also, it was found that the degree of non-ideality decreased with the increase in temperature. The behaviour of the vapour phase was shown also to be nearly ideal. The excess Gibbs free energy of mixing was calculated, and it was found to be non-symmetrical with mole fraction. On increasing the temperature of the system, the liquid composition corresponding to the maximum G^E tended to shift to a higher benzene concentration, whilst at a fixed liquid composition, G^E initially decreased and then remained stationary or increased again. This was thought to be due to differences in the molar volumes of the two components.     

An investigation into UK government policy and legislation to renewable energy and greenhouse gas reduction commitments

Clean Technologies and Environmental Policy - The UK has committed to various legally binding targets with regard to renewable energy technology and greenhouse gas reduction. As a result,...     

Uptake of the food-derived heterocyclic amine carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and its N-hydroxy metabolite into rat pancreatic acini and hepatocytes in vitro

Sinc DNA adducts of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) are formed at relatively high levels in the rat pancreas but not liver, we examined the uptake of PhIP and its N-hydroxy metabolite (N-OH-PhIP) into pancreatic acini and hepatocytes to determine if differential tissue uptake was a factor modulating the formation of PhIP-DNA adducts. In addition, since the precursors of PhIP formation are two amino acids and since various amino acid transporters have been identified in the pancreas, the possible involvement of these transporters in the uptake of PhIP and N-OH-PhIP was investigated. The uptake both heterocyclic compounds into both tissue preparations was rapid, with maximal uptake occurring with 1-2 min. However, PhIP uptake into pancreatic acini was significantly (2-way ANOVA, P < 0.05) greater than uptake of N-OH-PhIP into pancreatic acini and the uptake of both PhIP and N-OH-PhIP into hepatocytes. Although uptake was rapid, efflux of both compounds from both tissue preparations was also rapid. However, the efflux rate constant (1.86 +/- 0.6/min, mean +/- SEM) for PhIP) was significantly lower (Student's t-test, P < 0.05) than that for N-OH-PhIP (4.14 +/- 0.04/min) from pancreatic acini. This, combined with the increased uptake of PhIP into pancreatic acini , suggests that there is substantial but reversible binding of PhIP in the pancreas. The uptake of both PhIP and N-OH-PhIP into pancreatic acini and hepatocytes was not affected by the presence of various amino acids in the incubation buffer, indicating that amino acid transporters are not involved in uptake of these compounds. Furthermore, uptake of both compounds did not appear to be dependent on metabolic energy supply. The above data, together with the high octanol:buffer partition coefficients (logP = 1.322 and 1.301 for PhiP and N-OH-PhIP respectively) suggest that both uptake and efflux of PhIP and N-OH-PhIP are consistent with a process of passive diffusion. The tissue binding characteristics for PhIP in the pancreas may create conditions whereby pancreatic cytochrome P450 1A1 can catalyse the formation of N-OH-PhIP. While N-OH-PhIP is not the ultimate reactive DNA binding species, it has been shown to directly bind to and form DNA adducts. Therefore, it is possible that the apparent selective accumulation of PhIP may contribute to the high level of PhIP-DNA adducts formed in the rat pancreas.     

Chronic expression of P-selectin on endothelial cells stimulated by the T-cell cytokine, interleukin-3

P-selectin expressed on the surface of endothelium mediates leukocyte adhesion in vitro and rolling in vivo. Several inducers of cell-surface P-selectin expression on endothelial cells (EC) have previously been identified, all of which yield transient cell-surface expression of P-selectin lasting minutes to a few hours. We now show that a T-lymphocyte product, interleukin-3 (IL-3), stimulates the long-term endothelial cells (HUVEC). IL-3 induced cell-surface P-selectin expression in two phases. An initial peak at 10 minutes was followed by a prolonged upregulation beginning 16 hours after IL-3 addition and lasting at least 4 days. The level of P-selectin expression induced by IL-3 added for 48 hours was similar to that induced by treatment of HUVEC for 10 minutes with thrombin, and the effect of adding IL-3 for 48 hours followed by thrombin for 10 minutes was additive. Induction of cell-surface P-selectin expression by IL-3 was blocked by pretreatment of EC with a blocking monoclonal antibody against the IL-3 receptor alpha-chain. Lipopolysaccharide (LPS), tumor necrosis factor alpha (TNF alpha) and a mutant form of IL-3 with decreased potency did not induce cell-surface P-selectin expression after 48 hours' incubation with HUVEC, suggesting that the effect was specific to IL-3. The increase in cell-surface P-selectin expression occurring after 16 hours of incubation with IL-3 was accompanied by a similar prolonged increase in the steady-state mRNA level that was not observed at 10 minutes after IL-3 addition. As T-lymphocyte infiltration is a hallmark of chronic inflammation, our observations suggest that the secretion of IL-3 by T lymphocytes may serve to maintain the inflammatory state during chronic inflammation.     

Introduction to the special issue on methodological issues in psychological assessment research.

Our primary goal in this special issue on research methodology is to explore methodological issues across a broad range of psychological assessment research and to highlight pitfalls and problems that often plague researchers engaged in this pursuit. We believe that the methodological articles in this special issue will serve as an important resource for future research in the field of personality assessment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)