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Experimental Control (experimental + control)
Selected AbstractsPolysomnography Necessitates Experimental Control of the "First Night Effect"HEADACHE, Issue 9 2001Jeanetta C. Rains PhD No abstract is available for this article. [source] Idiographically Determined Versus Standard Absorption Periods in Alcohol Administration StudiesALCOHOLISM, Issue 5 2010Rebecca L. Schacht Background:, Effects of alcohol vary depending on blood alcohol level and limb. Some researchers use standard absorption periods (SAPs) to determine when postdrinking experimental protocols should begin. Others use an idiographically determined absorption period (IDAP) based on criterion breath alcohol concentration (BrAC). We investigated and compared the characteristics of each method. Methods:, Sixty-eight social drinkers (47% women) consumed a bolus dose of alcohol intended to raise BrAC to 0.08%. BrACs were recorded every 3 minutes until beginning to descend. Minutes to reach criterion BrAC (0.06%) and between-subjects postdrinking BrAC variability were analyzed. Results:, Mean time to reach 0.06% BrAC was 22.9 ± 14.6 minutes. Standard deviations in BrAC were 4 times greater using SAPs compared to IDAPs. Ten percent of participants' BrAC readings were on the descending limb 30 minutes postdrinking, and 25% were descending at 45 minutes postdrinking. Conclusions:, IDAPs result in less BrAC variability and may reduce experimental noise relative to SAPs. Experimental control in future alcohol administration studies may be enhanced by the use of IDAPs instead of SAPs. [source] Realism, Regularity and Social ExplanationJOURNAL FOR THE THEORY OF SOCIAL BEHAVIOUR, Issue 2 2003Stephen Kemp Stephen Kemp and John Holmwood, Realism, Regularity and Social Explanation, pp. 165,187. This article explores the difficulties raised for social scientific investigation by the absence of experiment, critically reviewing realist responses to the problem such as those offered by Bhaskar, Collier and Sayer. It suggests that realist arguments for a shift from prediction to explanation, the use of abstraction, and reliance upon interpretive forms of investigation fail to demonstrate that these approaches compensate for the lack of experimental control. Instead, it is argued that the search for regularities, when suitably conceived, provides the best alternative to experiment for the social sciences. [source] Evaluation of Myocardial Performance with Conventional Single-Site Ventricular Pacing and Biventricular Pacing in a Canine Model of Atrioventricular BlockJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 9 2003PATRICIO A. FRIAS M.D. Introduction: The aim of this study was to evaluate epicardial biventricular pacing as a means of maintaining synchronous ventricular activation in an acute canine model of AV block with normal ventricular anatomy and function. Chronic single-site ventricular pacing results in dyssynchronous ventricular activation and may contribute to ventricular dysfunction. Biventricular pacing has been used successfully in adult patients with congestive heart failure. Methods and Results: This was an acute study of open chest mongrel dogs (n = 13). ECG, left ventricular (LV), aortic, and pulmonary arterial pressures were measured. LV impedance catheters were used to assess cardiodynamics using instantaneous LV pressure-volume relations (PVR). Following radiofrequency ablation of the AV node, a temporary pacemaker was programmed 10 beats/min above the intrinsic atrial rate, with an AV interval similar to the baseline intrinsic PR interval. The pacing protocol consisted of 5-minute intervals with the following lead configurations: right atrium-right ventricular apex (RA-RVA), RA-LV apex (LVA), and RA-biventricular using combinations of four ventricular sites (RVA, RV outflow tract [RVOT], LVA, LV base [LVB]). RA-RVA was used as the experimental control. LV systolic mechanics, as measured by the slope of the end-systolic (Ees) PVR (ESPVR, mmHg/cc), was statistically greater (P < 0.05) with all modes of biventricular pacing (RA-RVA/LVA 20.0 ± 2.9, RA-RVA/LVB 18.4 ± 2.9, RA-RVOT/LVA 15.1 ± 1.8, RA-RVOT/LVB 17.6 ± 2.9) compared to single-site ventricular pacing (RA-RVA 12.8 ± 1.6). Concurrent with this improvement in myocardial performance was a shortening of the QRS duration (RA-RVA 97.7 ± 2.9 vs RA-RVA/LVA 75.7 ± 4.9, RA-RVA/LVB 70.3 ± 4.9, RA-RVOT/LVA 65.3 ± 4.4, and RA-RVOT/LVB 76.7 ± 5.9, P < 0.05). Conclusion: In this acute canine model of AV block, QRS duration shortened and LV performance improved with epicardial biventricular pacing compared to standard single-site ventricular pacing. (J Cardiovasc Electrophysiol, Vol. 14, pp. 996-1000, September 2003) [source] Successful behavioral strategy to unite mother and infant rhesus monkeys (Macaca mulatta) after cesarean delivery ,AMERICAN JOURNAL OF PRIMATOLOGY, Issue 6 2009Angela M. Ruggiero Abstract Developmental studies of pre- to postnatal continuities in rhesus monkeys sometimes require infants be reared with their mothers. However, complications during pregnancy or experimental designs may require cesarean delivery. Owing to lack of published information on this subject, strategies are needed to introduce mothers to their infants following cesarean delivery. Using positive and negative reinforcement techniques we attempted to unite six infant rhesus macaques, Macaca mulatta, to their mothers following c-sections. For our seventh subject, we attempted to cross-foster an infant onto an unrelated female after she had undergone a cesarean surgery for a late-term spontaneous abortion. The mothers varied in age, parity, previous postnatal mothering experience with infants, housing earlier to delivery, and housing subsequent to introduction. Although there were large individual differences among the mother,infant pairs, all seven introductions were successful. The mothers learned to accept and care for their infants from the continuous application of operant conditioning techniques. These data suggest that mother-rearing following cesarean section is a realistic possibility whether required for clinical reasons or for proper experimental control. Furthermore, the ability to successfully mother-rear infants produced from cesarean delivery lessens the impact this potential confound of not being reared by their mothers exerts on many types of developmental studies. Am. J. Primatol. 71:510,522, 2009. © 2009 Wiley-Liss, Inc. [source] In search of new tractable diatoms for experimental biologyBIOESSAYS, Issue 7 2008Victor A. Chepurnov Diatoms are a species-rich group of photosynthetic eukaryotes, with enormous ecological significance and great potential for biotechnology. During the last decade, diatoms have begun to be studied intensively using modern molecular techniques and the genomes of four diatoms have been wholly or partially sequenced. Although new insights into the biology and evolution of diatoms are accumulating rapidly due to the availability of reverse genetic tools, the full potential of these molecular biological approaches can only be fully realized if experimental control of sexual crosses becomes firmly established and widely accessible to experimental biologists. Here we discuss the issue of choosing new models for diatom research, by taking into account the broader context of diatom mating systems and the place of sex in relation to the intricate cycle of cell size reduction and restitution that is characteristic of most diatoms. We illustrate the results of our efforts to select and develop experimental systems in diatoms, using species with typical life cycle attributes, which could be used as future model organisms to complement existing ones. BioEssays 30:692,702, 2008. © 2008 Wiley Periodicals, Inc. [source] Heterosis performance of yield and fibre quality in F1 and F2 hybrids in upland cottonPLANT BREEDING, Issue 3 2004Y. T. Wu Abstract Because of the difficulty of producing F1 hybrid seeds by hand emasculation and pollination, wide use of heterosis in cotton production has been limited in China. The objective of this study was to evaluate the potential of F2 hybrids for yield and fibre quality. A half diallel involving eight parents and their F1 and F2 hybrids was grown in replicated studies at Linqing and Nanjing in 1999 and Nanjing in 2000. Yield and fibre quality was determined for all 64 entries. Fibre quality was also determined for parents and F1s, but only for Zhongmiansuo 28 (ZMS28), Xiangzamian 2 (XZM2) and Wanmian 13 (WM13) F2s. These three F2 hybrids are extensively planted in China and provide experimental controls with which to compare the performance of new hybrids. Average yield heterosis for F1s and F2s was 15.9 and 9.2%, respectively. Inbreeding depression for yield varied but some F2s greatly out-yielded the best variety. Average F1 heterosis was 6.7, 6.2 and 2.9%, respectively for number of bolls per unit area, boll weight, and lint percentage. The average F2 heterosis for the same traits was 4.4, 3.3 and 1.6%, respectively. F1 heterosis for fibre traits was low. In general, parental average was a good indicator of the yield and fibre quality of F1 hybrids. These encouraging results suggest there is sufficient heterosis for yield to use F2s in China. [source] Habitat specificity and home-range size as attributes of species vulnerability to extinction: a case study using sympatric rattlesnakesANIMAL CONSERVATION, Issue 4 2006J. L. Waldron Abstract Large home-range size and habitat specificity are two commonly cited ecological attributes that are believed to contribute to species vulnerability. The eastern diamondback rattlesnake Crotalus adamanteus is a declining species that occurs sympatrically with the more abundant canebrake rattlesnake Crotalus horridus in a portion of the south-eastern Coastal Plain, USA. In this study, we use the ecological similarities of the two species as experimental controls to test the role of home-range size and habitat specificity in the imperilment of the eastern diamondback rattlesnake. We used analysis of variance to investigate differences in home-range size between the two species, and home-range selection was modeled as habitat use versus availability with a case control sampling design using logistic regression. We failed to detect differences in home-range size between the two species; therefore, we could not identify home-range size as an attribute contributing to the imperilment of eastern diamondback rattlesnakes. Eastern diamondback rattlesnakes selected pine savannas to a degree that suggests that the species is a habitat specialist. Of the two factors examined, habitat specificity to the imperiled longleaf pine ecosystem may be a significant contributor to the decline of the eastern diamondback rattlesnake. [source] | |||||||||||||