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Substantial Limitations (substantial + limitation)
Selected AbstractsStep-Energy Barriers and Particle Shape Changes during CoarseningJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2002Brian W. Sheldon Models of particle shape changes usually do not account for the step-energy barrier associated with adding or removing additional atomic planes from a faceted surface. However, the step-energy barrier can be a substantial limitation when the free energy changes that drive particle shape changes are relatively low. A good example of this is particle coarsening. The analysis presented in this article describes dislocation-free particles with surfaces that have faceted and nonfaceted regions. When the chemical potential differences responsible for shape changes are too small to overcome the step-energy barrier, atomic layers cannot be added or removed from the facets. Even with this constraint, it is possible to add or remove atoms from the particle surface; however, this can cause the particle shape to differ substantially from the traditional equilibrium shape. [source] Few beetle species can be detected with 95% confidence using pitfall trapsAUSTRAL ECOLOGY, Issue 1 2010DON A. DRISCOLL Abstract False absences in wildlife surveys make it difficult to identify metapopulation processes, increase uncertainty of management decisions and bias parameter estimates in habitat models. Despite these risks, the number of species that can be detected with a certain probability in a community survey has rarely been examined. I sampled beetles over 5 months using pitfall trap grids at three rainforest locations in Tasmania, Australia. I compared detection probability for dispersed and clustered sampling schemes using a zero-inflated binomial model and a simpler occurrence method to calculate the probability of detection. After excluding extremely rare species, I analysed 12 of 121 species. Only three to six species could be detected with 95% probability using a sampling effort that is frequently applied in ecological studies. A majority of common species had a mid summer peak in detection probability meaning that survey effort could be reduced from 5 to 2 months with only a small reduction in data quality. Most species occurred at only a proportion of sample points within locations. Despite the implied spatial structuring, three small grids within a location detected 10 of 12 species as effectively as large, dispersed grids. This study warns that as little as 5% of the beetle fauna may have a 95% probability of detection using the frequently applied pitfall trap method, highlighting a substantial limitation in our ability to accurately map the distributions of ground invertebrates. Whether very large sample sizes can overcome this limitation remains to be examined. [source] Targeted group antenatal prevention of postnatal depression: a reviewACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2003M.-P. Austin Objective:, To review the efficacy of antenatal group interventions aimed at reducing postnatal depression (PND) in ,at risk' women. Method:, Medline, Psyclit, HEALTHSTAR, EMBASE, Cochrane library, UK National Research Register and CINHAL searches were performed from 1960 to December 2001 focussing on randomized controlled trials (RCTs). Results:, As statistical synthesis of the studies was not feasible, a qualitative review is provided. All five studies reviewed suffer from substantial limitations including small numbers; unrealistic effect sizes; large attrition rates; lack of a systematic approach in identifying those ,at risk' and thus clinically heterogenous samples. Three of the studies used unvalidated interventions that were educational or supportive in approach. While one such study reported a benefit of intervention, the largest study using a structured intervention, reported no effect. A very small study using interpersonal therapy, was promising but needs replication with an adequate sample size. Conclusion:, There is currently little evidence from RCTs to support the implementation of antenatal group interventions to reduce PND in ,at risk' women. Further studies addressing the significant methodological limitations are recommended before concluding that antenatal targeted interventions have no place in maternity care. [source] Retrospective database analysis on the effectiveness of typical and atypical antipsychotic drugs in an outpatient clinic settingHUMAN PSYCHOPHARMACOLOGY: CLINICAL AND EXPERIMENTAL, Issue 8 2007Cengiz Akkaya Abstract Objective To report the outcomes of a retrospective database analysis to compare the effectiveness of atypical and typical antipsychotic drugs. Methods Medical records of patients admitted to the psychiatry outpatient clinic between January 1998 and October 2005 were retrospectively reviewed. Data obtained from patient records were noted on a special form assessing four aspects of the treatment history: socio-demographic features, disease characteristics, initial treatment at the time of admission, and course of treatment. Patient groups (typical/atypical and Risperidone/Haloperidol/Olanzapine) were compared for time to all-cause medication discontinuation and rate of discontinuation. Results There was no statistically significant difference in the duration of treatment between patients using atypical (n,=,150) and typical (n,=,124) antipsychotics. The duration of treatment was significantly longer in patients on Haloperidol (n,=,91) compared with those on Risperidone (n,=,63). Rates of discontinuation over 18 months were 59.3% for patients on atypical antipsychotics and 57.3% for those on typical antipsychotics, and 68.3% for patients on Risperidone, 51.6% for patients on Haloperidol and 54.3% for patients on Olanzapine. Conclusion Despite our hypothesis patients with chronic schizophrenia discontinued their atypical and typical antipsychotics, at a high rate with no significant difference indicating substantial limitations in the effectiveness of these drugs. Copyright © 2007 John Wiley & Sons, Ltd. [source] High therapy adherence but substantial limitations to daily activities amongst members of the Dutch inflammatory bowel disease patients' organization: a patient empowerment studyALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2009J. E. BAARS Aliment Pharmacol Ther,30, 864,872 Summary Background, Adherence is important for successful treatment in inflammatory bowel disease (IBD) patients. Previous studies demonstrated high prevalence of non-adherence. Aim, To assess IBD-patients' perceptions of therapy adherence and disease-related functional status in members of the Dutch patients' association of Crohn's disease and ulcerative colitis (CCUVN). Methods, Inflammatory bowel disease-patients completed anonymously a survey at the website of the CCUVN. Statistical analysis was performed using principal component analysis, univariate and multivariate logistic regression. Results, The questionnaire was completed by 1067 patients [617 (58%) Crohn's disease (CD) and 450 (42%) ulcerative colitis (UC)]. Mean age was 43 years (s.d. 13.7); women (66%). Of 920 patients currently using medication, 797 (87%) were adherent. Of the patients using 5-ASA, 91% were adherent (527/582), vs. 96% using corticosteroids (316/330) and 97% (414/425) using immunosuppressives. CD patients (OR 1.54; 95% CI 1.05,2.27), patients with duration of disease ,8 years (OR 2.25; 95% CI 1.49,3.39) were more adherent. Fifty percent of patients reported a low functional status and were limited in daily activities. Conclusion, This population-based study shows high therapy adherence, but low functional status in Dutch CCUVN-related IBD-patients. The high adherence rate in this present study could be an effect of CCUVN membership. [source] | ||||||||||