Brain amino acid abnormalities in kidney disease and diabetes mellitus

The present postmortem study examines whether specific amino acid abnormalities associated with renal diseases or diabetes mellitus in animal experiments and on clinical examination may also be found in human brain samples obtained at clinical autopsies. The material includes 12 deceased with renal insufficiency, 23 deceased with diabetes mellitus and 26 control cases with lethal cardiovascular diseases (without a history of hepatic, renal or metabolic disturbances). The autopsy and clinical records were retrospectively analyzed for age, sex, postmortem delay, cause of death, substantial preexisting diseases and histological findings. The analysis of free amino acid concentrations in human brain specimens was performed applying a Beckman amino acid analyzer. The results were evaluated using the U-test according to Mann, Willcox and Whitney. A P-value less than 0.05 was considered to be significantly different. Differences of amino acid concentrations attributable to sex, age and postmortem delay were not significant. The comparison of postmortem amino acid concentrations in the brains of patients with diabetes mellitus and controls did not reveal relevant changes. However, the patients with renal diseases, as compared to controls, showed a significant cerebral increase of urea, phenylethanolamine and gamma-aminobutyric acid. Thus, the postmortem amino acid analysis may contribute to the understanding of pathophysiological mechanisms of uremic encephalopathy and may supplement the conventional postmortem morphological diagnosis in kidney diseases by indication of functional impairment.     

The economic model of voter participation: A further test

The central hypothesis of the economic model of voter participation was put to an empirical test. It was found that the coefficient of population size, which represents the subjective probability of affecting election results, is negative and significant in municipal local elections, but insignificant in national Knesset elections. Therefore, this variable is unable to represent subjective probability in the latter case.It was suggested that the economic model is more relevant to local elections than to Knesset elections. The empirical results revealed that the regression coefficients of municipal elections that took place separately from Knesset elections fit the expected outcome of the economic model whereas when municipal elections were held simultaneously with the Knesset election this did not hold true.     

Saudi Arabia's rapprochement with Israel: the national security imperatives

The purpose of this article is to examine the evolution of Israel's relations with Saudi Arabia since the establishment of the Jewish state in 1948. The author explains how the major events in the Middle East affected Saudi Arabia's foreign policy orientation. It shows how Saudi Arabia's policy toward Israel was affected by the deterioration in Saudi-Egyptian relations, by its quest for security in the Arabian Gulf region and by its aspiration to hegemony in the Middle East. The author argues that Saudi Arabia's policy toward Israel remained far less hostile than that of the Arab states surrounding Israel. In addition, it argues that it was not until 1973 that Saudi Arabia became seriously involved in the attempt to pressure Israel to withdraw from the territories it occupied in the Six-Day War. The author concludes by showing that neither Saudi Arabia's acquisition of the intelligence-gathering AWACS aircraft, nor Israel's invasion of Lebanon or the massacre of Palestinians in the refugee camps of Sabra and Shatila had a serious impact on the bilateral relations, and that it was not until the emergence of the Iranian nuclear threat that Saudi Arabia's relations with Israel began to improve.     

How Conditioning on Posttreatment Variables Can Ruin Your Experiment and What to Do about It

In principle, experiments offer a straightforward method for social scientists to accurately estimate causal effects. However, scholars often unwittingly distort treatment effect estimates by conditioning on variables that could be affected by their experimental manipulation. Typical examples include controlling for posttreatment variables in statistical models, eliminating observations based on posttreatment criteria, or subsetting the data based on posttreatment variables. Though these modeling choices are intended to address common problems encountered when conducting experiments, they can bias estimates of causal effects. Moreover, problems associated with conditioning on posttreatment variables remain largely unrecognized in the field, which we show frequently publishes experimental studies using these practices in our discipline's most prestigious journals. We demonstrate the severity of experimental posttreatment bias analytically and document the magnitude of the potential distortions it induces using visualizations and reanalyses of real‐world data. We conclude by providing applied researchers with recommendations for best practice.     

Different Kinds of Lonely: Dimensions of Isolation and Substance Use in Adolescence

Social isolation is broadly associated with poor mental health and risky behaviors in adolescence, a time when peers are critical for healthy development. However, expectations for isolates’ substance use remain unclear. Isolation in adolescence may signal deviant attitudes or spur self-medication, resulting in higher substance use. Conversely, isolates may lack access to substances, leading to lower use. Although treated as a homogeneous social condition for teens in much research, isolation represents a multifaceted experience with structurally distinct network components that present different risks for substance use. This study decomposes isolation into conceptually distinct dimensions that are then interacted to create a systematic typology of isolation subtypes representing different positions in the social space of the school. Each isolated position’s association with cigarette, alcohol, and marijuana use is tested among 9^th grade students (n?=?10,310, 59% female, 83% white) using cross-sectional data from the PROSPER study. Different dimensions of isolation relate to substance use in distinct ways: unliked isolation is associated with lower alcohol use, whereas disengagement and outside orientation are linked to higher use of all three substances. Specifically, disengagement presents risks for cigarette and marijuana use among boys, and outside orientation is associated with cigarette use for girls. Overall, the adolescents disengaged from their school network who also identify close friends outside their grade are at greatest risk for substance use. This study indicates the importance of considering the distinct social positions of isolation to understand risks for both substance use and social isolation in adolescence.     

Advances and Opportunities in the Study of Political Communication,Foreign Policy,and Public Opinion

We review contemporary research at the intersection of political communication and foreign policy, highlighting four themes: 1) new, more realistic and psychologically-nuanced approaches that account for limited information and issue framing; 2) the question of whether the flow of communication between the state and the public is best conceived as a closed system, or one that is open to outside influences such as foreign elites; 3) how variations in political or governmental structures, patterns of media access or ownership, and other institutional factors can alter the relationships between foreign policy and communication processes; and 4) whether or not it is useful to distinguish between foreign and domestic policymaking when analyzing the role of political communication. We also suggest avenues for further research in each section and conclude by summarizing these opportunities for continued theoretical development.     

Fairtrade and Labour Markets in Ethiopia and Uganda

Drawing on four years of fieldwork in Ethiopia and Uganda, this paper addresses gaps in knowledge about the mechanisms linking agricultural exports with poverty reduction, the functioning of rural labour markets, and the relevance to the lives of the poorest people of Fairtrade. Statistical analysis of survey evidence, complemented by qualitative research, highlights the relatively poor payment and non-pay working conditions of those employed in research sites dominated by Fairtrade producer organisations. We conclude that Fairtrade is not an effective way to improve the welfare of the poorest rural people.