			Home About us Contact

Powerful Effects (powerful + effects)

Distribution by Scientific Domains

Psychology	28%
Humanities and Social Sciences	28%

Selected Abstracts

MDMA, methamphetamine and their combination: possible lessons for party drug users from recent preclinical research

DRUG AND ALCOHOL REVIEW, Issue 1 2007
KELLY J. CLEMENS
Abstract The substituted amphetamines 3,4-methylenedioxymethamphetamine (MDMA, ,Ecstasy') and methamphetamine (METH, ,ice', ,speed') are increasingly popular drugs amongst party-drug users. Studies with humans have investigated the acute and possible long-term adverse effects of these drugs, yet outcomes of such studies are often ambiguous due to a variety of confounding factors. Studies employing animal models have value in determining the acute and long-term effects of MDMA and METH on brain and behaviour. Self-administration studies show that intravenous METH is a particularly potent reinforcer in rats and other species. In contrast, MDMA appears to have powerful effects in enhancing social behaviour in laboratory animals. Brief exposure to MDMA or METH may produce long-term reductions in dopamine, serotonin and noradrenaline in the brain and alterations in the density of various receptor and transporter proteins. However it is still unclear, particularly in the case of MDMA, whether this reflects a ,neurotoxic' effect of the drug. Lasting alterations in social behaviour, anxiety, depressive symptoms and memory have been demonstrated in laboratory rats given MDMA or METH and this matches long-term changes reported in some human studies. Recent laboratory studies suggest that MDMA/METH combinations may produce greater adverse neurochemical and behavioural effects than either drug alone. This is of some concern given recent evidence that party drug users may be frequently exposed to this combination of drugs. [source]

Teachers, Schools, and Academic Achievement

ECONOMETRICA, Issue 2 2005
Steven G. Rivkin
This paper disentangles the impact of schools and teachers in influencing achievement with special attention given to the potential problems of omitted or mismeasured variables and of student and school selection. Unique matched panel data from the UTD Texas Schools Project permit the identification of teacher quality based on student performance along with the impact of specific, measured components of teachers and schools. Semiparametric lower bound estimates of the variance in teacher quality based entirely on within-school heterogeneity indicate that teachers have powerful effects on reading and mathematics achievement, though little of the variation in teacher quality is explained by observable characteristics such as education or experience. The results suggest that the effects of a costly ten student reduction in class size are smaller than the benefit of moving one standard deviation up the teacher quality distribution, highlighting the importance of teacher effectiveness in the determination of school quality. [source]

Glutamate enhances proliferation and neurogenesis in human neural progenitor cell cultures derived from the fetal cortex

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 3 2006
Masatoshi Suzuki
Abstract Excitatory amino acids such as glutamate play important roles in the central nervous system. We previously demonstrated that a neurosteroid, dehydroepiandrosterone (DHEA), has powerful effects on the cell proliferation of human neural progenitor cells (hNPC) derived from the fetal cortex, and this effect is modulated through NMDA receptor signaling. Here, we show that glutamate can significantly increase the proliferation rates of hNPC. The increased proliferation could be blocked by specific NMDA receptor antagonists, but not other glutamate antagonists for kainate,AMPA or metabotropic receptors. The NR1 subunit of the NMDA receptor was detectable in elongated bipolar or unipolar cells with small cell bodies. These NR1-positive cells were colocalized with GFAP immunoreactivity. Detection of the phosphorylation of cAMP response element-binding protein (pCREB) revealed that a subset of NR1-positive hNPC could respond to glutamate. Furthermore, we hypothesized that glutamate treatment may affect mainly the hNPC with a radial morphology and found that glutamate as well as DHEA selectively affected elongated hNPC; these elongated cells may be a type of radial glial cell. Finally we asked whether the glutamate-responsive hNPC had an increased potential for neurogenesis and found that glutamate-treated hNPC produced significantly more neurons following differentiation. Together these data suggest that glutamate stimulates the division of human progenitor cells with neurogenic potential. [source]

Is the placebo powerless?

JOURNAL OF INTERNAL MEDICINE, Issue 2 2004
Update of a systematic review with 52 new randomized trials comparing placebo with no treatment
Abstract. Background., It is widely believed that placebo interventions induce powerful effects. We could not confirm this in a systematic review of 114 randomized trials that compared placebo-treated with untreated patients. Aim., To study whether a new sample of trials would reproduce our earlier findings, and to update the review. Methods., Systematic review of trials that were published since our last search (or not previously identified), and of all available trials. Results., Data was available in 42 out of 52 new trials (3212 patients). The results were similar to our previous findings. The updated review summarizes data from 156 trials (11 737 patients). We found no statistically significant pooled effect in 38 trials with binary outcomes, relative risk 0.95 (95% confidence interval 0.89,1.01). The effect on continuous outcomes decreased with increasing sample size, and there was considerable variation in effect also between large trials; the effect estimates should therefore be interpreted cautiously. If this bias is disregarded, the pooled standardized mean difference in 118 trials with continuous outcomes was ,0.24 (,0.31 to ,0.17). For trials with patient-reported outcomes the effect was ,0.30 (,0.38 to ,0.21), but only ,0.10 (,0.20 to 0.01) for trials with observer-reported outcomes. Of 10 clinical conditions investigated in three trials or more, placebo had a statistically significant pooled effect only on pain or phobia on continuous scales. Conclusion., We found no evidence of a generally large effect of placebo interventions. A possible small effect on patient-reported continuous outcomes, especially pain, could not be clearly distinguished from bias. [source]

Racial Reconciliation in South Africa:Interracial Contact and Changes over Time

JOURNAL OF SOCIAL ISSUES, Issue 2 2010
James L. Gibson
Relying upon,Gibson's (2004),theory equating lack of prejudice with interracial "reconciliation," we investigate racial attitudes based on a 2004 nationally representative survey of South Africans. We begin by documenting substantial group-based differences in intergroup prejudice, with Blacks being considerably less reconciled with Whites as compared to the three racial minorities' levels of reconciliation with Blacks. We also discover that the Black majority has become less reconciled with Whites over the period from Gibson's survey (in 2001) to the current survey (in 2004). Improvement in racial attitudes is observed among the other three groups. We next investigate intergroup contact as an explanation of differences in attitudes, finding some effects of mere contact and powerful effects of intimate contact. However, the consequences of contact differ across the various racial groups. [source]

Using Experiments to Estimate the Effects of Education on Voter Turnout

AMERICAN JOURNAL OF POLITICAL SCIENCE, Issue 1 2010
Rachel Milstein Sondheimer
The powerful relationship between education and voter turnout is arguably the most well-documented and robust finding in American survey research. Yet the causal interpretation of this relationship remains controversial, with many authors suggesting that the apparent link between education and turnout is spurious. In contrast to previous work, which has relied on observational data to assess the effect of education on voter turnout, this article analyzes two randomized experiments and one quasi-experiment in which educational attainment was altered exogenously. We track the children in these experiments over the long term, examining their voting rates as adults. In all three studies, we find that exogenously induced changes in high school graduation rates have powerful effects on voter turnout rates. These results imply that the correlation between education and turnout is indeed causal. We discuss some of the pathways by which education may transmit its influence. [source]

Ayahuasca and Spiritual Crisis: Liminality as Space for Personal Growth

ANTHROPOLOGY OF CONSCIOUSNESS, Issue 2 2008
SARA E. LEWIS
ABSTRACT There is an increased controversy surrounding Westerners' use of ayahuasca. One issue of importance is psychological resiliency of users and lack of screening by ayahuasca tourism groups in the Amazon. Given the powerful effects of ayahuasca coupled with lack of cultural support, Western users are at increased risk for psychological distress. Many Westerners who experience psychological distress following ayahuasca ceremonies report concurrently profound spiritual experiences. Because of this, it may be helpful to consider these episodes "spiritual emergencies," or crises resulting from intense and transformative spiritual experiences. Although the author warns readers to avoid romantic comparisons of Western ayahuasca users to shamans, ethnographic data on indigenous shamanic initiates along with theory on liminality may be of some use to understand difficult experiences that accompany ayahuasca use. Given that psychotherapy is culturally sanctioned, therapists trained in treating spiritual crises can help Western ayahuasca users make meaning of their distress. Three case studies are offered as examples of individuals working through various sorts of crises following ayahuasca ceremonies. [source]