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Many Experiments (many + experiment)
Selected AbstractsReactance and the dynamics of disagreement: multiple paths from threatened freedom to resistance to persuasionEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 5 2006Paul J. Silvia Many experiments show that threats to attitudinal freedom create reactance, but the underlying dynamics of reactance-based disagreement have not received much attention. The present experiments identified two paths from threats to disagreement. In one path, threats to attitudinal freedom directly motivate disagreement; in the other, negative cognitive responses mediate the threat's effect on disagreement. Two experiments demonstrated the causes and consequences of each path from threat to persuasion. When a communicator threatened freedom at the beginning of the message, unfavorable cognitive responses (counterarguing, negative perceptions of the source's credibility) fully mediated the effect of threat on disagreement. When the threat appeared at the end of the message however, threat had a direct, unmediated effect on disagreement (Experiment 1). The two paths had different consequences for sleeper effects: disagreement rooted in negative cognitive responses persisted, whereas disagreement directly motivated by the threat declined when the threat was removed (Experiment 2). Implications for reactance and for threat-based sleeper effects are discussed. Copyright © 2006 John Wiley & Sons, Ltd. [source] Structural determination of the O-chain polysaccharide from Agrobacterium tumefaciens, strain DSM 30205FEBS JOURNAL, Issue 12 2002Cristina De Castro Agrobacterium tumefaciens is a Gram-negative, phytopathogenic bacterium and is characterized by an unique mode of action on dicotyledonous plants: it is able to genetically modify the host, and because of this feature, it is used as a tool for transgenic plants. Many experiments have demonstrated that lipopolysaccharides (LPSs) play an important role for the disease development, as they are involved in the adhesion process of the bacterium on the plant cell wall. Despite the wealth of information on the role of LPS on phytopathogenesis, the present paper appears as the first report on the molecular primary structure of the O-chain produced from Agrobacterium. Its repeating unit was determined by means of chemical and spectroscopical analysis, and has the following structure: (3)-,- d -Araf -(1,3)-,- l -Fucp -(1,. [source] Social Influence: Representation, Imagination and FactsJOURNAL FOR THE THEORY OF SOCIAL BEHAVIOUR, Issue 4 2007STÉPHANE LAURENS ABSTRACT Studies on social influence bring us to fear that influence may alienate us and turn us into an agent of the will and desire of the other. This fear relies on a representation of the relationship of influence: it would be an asymmetrical relationship involving two basically opposite and complementary entities, the source (who has a desire, a will, a power or, failing that, a technique) and the target (who is subjected, subordinate). If some experiments in social psychology demonstrate the effectiveness of some techniques of influence and manipulation, they must however be analysed in detail. Many experiments and theories show that influence is not basically nonreciprocal. These works are neglected because they are too different from the imaginary representation of influence that dominates both social psychology and common sense. [source] Mixture and mixture,process variable experiments for pharmaceutical applicationsPHARMACEUTICAL STATISTICS: THE JOURNAL OF APPLIED STATISTICS IN THE PHARMACEUTICAL INDUSTRY, Issue 4 2004Christine M. Anderson-Cook Abstract Many experiments in research and development in the pharmaceutical industry involve mixture components. These are experiments in which the experimental factors are the ingredients of a mixture and the response variable is a function of the relative proportion of each ingredient, not its absolute amount. Thus the mixture ingredients cannot be varied independently. A common variation of the mixture experiment occurs when there are also one or more process factors that can be varied independently of each other and of the mixture components, leading to a mixture,process variable experiment. We discuss the design and analysis of these types of experiments, using tablet formulation as an example. Our objective is to encourage greater utilization of these techniques in pharmaceutical research and development. Copyright © 2004 John Wiley & Sons Ltd. [source] Blunt egg pole holds cues for alien egg discrimination: experimental evidenceJOURNAL OF AVIAN BIOLOGY, Issue 2 2010L. Pola, iková Eggshell colour patterns play a crucial role in avian host,parasite coevolution. In contrast to many experiments investigating general host egg discrimination abilities, studies testing where specific recognition cues are located on the eggshells (on blunt, sharp or both egg poles) are lacking. Previous studies suggested that discrimination cues might be located at the blunt egg pole, where the shell patterning is typically concentrated. We tested this hypothesis experimentally in species subject to interspecific (great reed warblers Acrocephalus arundinaceus, reed warblers A. scirpaceus), and also intraspecific parasitism (song thrushes Turdus philomelos, blackbirds T. merula). We examined host responses towards two types of intraspecific eggs painted non-mimetic immaculate blue either at blunt or sharp poles. All four species rejected eggs manipulated at the blunt pole at significantly higher rates, indicating that they perceive the critical recognition cues in the same egg part. Thus, the presence of egg recognition cues at the blunt egg pole may be a general phenomenon in birds parasitized by both intraspecific and interspecific parasites. [source] Use of Nitrogen as a Blowing Agent for the Production of Fine-Celled High-Density Polyethylene Foams,MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2006John W. S. Lee Abstract Summary: While many experiments have been performed to examine the effects of administering CO2 as a blowing agent in the foaming process, very few studies have investigated the use of N2 for this purpose. In this study, foaming experiments were conducted in extrusion using HDPE as a polymeric material and N2 as a blowing agent. Talc was used as a nucleating agent, and three different pressure-drop rates were applied to study the effects of pressure-drop rates on HDPE foams. The experimental results revealed that the void fraction of high-density foams blown with N2 was not affected by the die temperature, contrasting the situation in low-density foams. Surprisingly, it was the cell density which determined the void fraction of high-density foams. It was also found that the use of talc significantly increased the cell density and the void fraction of the foams and minimized the role played by the pressure-drop rate in cell nucleation. Effect of N2 content on the cell density of HDPE foams. [source] Effects of Growth Hormone on Female Reproductive OrgansANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 5 2001G. G. Kaiser During the last decade many experiments have been performed to study the effects of growth hormone (GH, somatotropin) on reproductive functions. Most of the studies found only slight or no effects of GH treatment, both on the oestrous cycle and on gonadotropin, progesterone, or oestrogen serum levels. In GH-treated animals, elevated levels of insulin-like growth factor I and GH in the serum could be correlated with an increased number of small (<5 mm in diameter) ovarian follicles, possibly as a consequence of a reduction of apoptosis and follicular atresia. There is still controversy over the effects of GH on in vivo and in vitro embryo production and on the gestation period. Recent studies produced some evidence that GH-receptor is expressed in ovarian tissue, implying a direct role for GH in the ovary. [source] Structure-factor extrapolation using the scalar approximation: theory, applications and limitationsACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2007Ulrich K. Genick For many experiments in macromolecular crystallography, the overall structure of the protein/nucleic acid is already known and the aim of the experiment is to determine the effect a chemical or physical perturbation/activation has on the structure of the molecule. In a typical experiment, an experimenter will collect a data set from a crystal in the unperturbed state, perform the perturbation (i.e. soaking a ligand into the crystal or activating the sample with light) and finally collect a data set from the perturbed crystal. In many cases the perturbation fails to activate all molecules, so that the crystal contains a mix of molecules in the activated and native states. In these cases, it has become common practice to calculate a data set corresponding to a hypothetical fully activated crystal by linear extrapolation of structure-factor amplitudes. These extrapolated data sets often aid greatly in the interpretation of electron-density maps. However, the extrapolation of structure-factor amplitudes is based on a mathematical shortcut that treats structure factors as scalars, not vectors. Here, a full derivation is provided of the error introduced by this approximation and it is determined how this error scales with key experimental parameters. The perhaps surprising result of this analysis is that for most structural changes encountered in protein crystals, the error introduced by the scalar approximation is very small. As a result, the extrapolation procedure is largely limited by the propagation of experimental uncertainties of individual structure-factor amplitudes. Ultimately, propagation of these uncertainties leads to a reduction in the effective resolution of the extrapolated data set. The program XTRA, which implements SASFE (scalar approximation to structure-factor extrapolation), performs error-propagation calculations and determines the effective resolution of the extrapolated data set, is further introduced. [source] Response Surface Designs for Experiments in BioprocessingBIOMETRICS, Issue 2 2006Steven G. Gilmour Summary Many processes in the biological industries are studied using response surface methodology. The use of biological materials, however, means that run-to-run variation is typically much greater than that in many experiments in mechanical or chemical engineering and so the designs used require greater replication. The data analysis which is performed may involve some variable selection, as well as fitting polynomial response surface models. This implies that designs should allow the parameters of the model to be estimated nearly orthogonally. A class of three-level response surface designs is introduced which allows all except the quadratic parameters to be estimated orthogonally, as well as having a number of other useful properties. These subset designs are obtained by using two-level factorial designs in subsets of the factors, with the other factors being held at their middle level. This allows their properties to be easily explored. Replacing some of the two-level designs with fractional replicates broadens the class of useful designs, especially with five or more factors, and sometimes incomplete subsets can be used. It is very simple to include a few two- and four-level factors in these designs by excluding subsets with these factors at the middle level. Subset designs can be easily modified to include factors with five or more levels by allowing a different pair of levels to be used in different subsets. [source] Sensitivity Analyses Comparing Outcomes Only Existing in a Subset Selected Post-Randomization, Conditional on Covariates, with Application to HIV Vaccine TrialsBIOMETRICS, Issue 2 2006Bryan E. Shepherd Summary In many experiments, researchers would like to compare between treatments and outcome that only exists in a subset of participants selected after randomization. For example, in preventive HIV vaccine efficacy trials it is of interest to determine whether randomization to vaccine causes lower HIV viral load, a quantity that only exists in participants who acquire HIV. To make a causal comparison and account for potential selection bias we propose a sensitivity analysis following the principal stratification framework set forth by Frangakis and Rubin (2002, Biometrics58, 21,29). Our goal is to assess the average causal effect of treatment assignment on viral load at a given baseline covariate level in the always infected principal stratum (those who would have been infected whether they had been assigned to vaccine or placebo). We assume stable unit treatment values (SUTVA), randomization, and that subjects randomized to the vaccine arm who became infected would also have become infected if randomized to the placebo arm (monotonicity). It is not known which of those subjects infected in the placebo arm are in the always infected principal stratum, but this can be modeled conditional on covariates, the observed viral load, and a specified sensitivity parameter. Under parametric regression models for viral load, we obtain maximum likelihood estimates of the average causal effect conditional on covariates and the sensitivity parameter. We apply our methods to the world's first phase III HIV vaccine trial. [source] Microfluidic biolector,microfluidic bioprocess control in microtiter platesBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2010Matthias Funke Abstract In industrial-scale biotechnological processes, the active control of the pH-value combined with the controlled feeding of substrate solutions (fed-batch) is the standard strategy to cultivate both prokaryotic and eukaryotic cells. On the contrary, for small-scale cultivations, much simpler batch experiments with no process control are performed. This lack of process control often hinders researchers to scale-up and scale-down fermentation experiments, because the microbial metabolism and thereby the growth and production kinetics drastically changes depending on the cultivation strategy applied. While small-scale batches are typically performed highly parallel and in high throughput, large-scale cultivations demand sophisticated equipment for process control which is in most cases costly and difficult to handle. Currently, there is no technical system on the market that realizes simple process control in high throughput. The novel concept of a microfermentation system described in this work combines a fiber-optic online-monitoring device for microtiter plates (MTPs),the BioLector technology,together with microfluidic control of cultivation processes in volumes below 1,mL. In the microfluidic chip, a micropump is integrated to realize distinct substrate flow rates during fed-batch cultivation in microscale. Hence, a cultivation system with several distinct advantages could be established: (1) high information output on a microscale; (2) many experiments can be performed in parallel and be automated using MTPs; (3) this system is user-friendly and can easily be transferred to a disposable single-use system. This article elucidates this new concept and illustrates applications in fermentations of Escherichia coli under pH-controlled and fed-batch conditions in shaken MTPs. Biotechnol. Bioeng. 2010;107: 497,505. © 2010 Wiley Periodicals, Inc. [source] | |||||||||||||||||||