The Birth of Social Choice Theory from the Spirit of Mathematical Logic: Arrow’s Theorem in the Framework of Model Theory

Arrow’s axiomatic foundation of social choice theory can be understood as an application of Tarski’s methodology of the deductive sciences—which is closely related to the latter’s foundational contribution to model theory. In this note we show in a model-theoretic framework how Arrow’s use of von Neumann and Morgenstern’s concept of winning coalitions allows to exploit the algebraic structures involved in preference aggregation; this approach entails an alternative indirect ultrafilter proof for Arrow’s dictatorship result. This link also connects Arrow’s seminal result to key developments and concepts in the history of model theory, notably ultraproducts and preservation results.     

Zur Anerkennung von psychotherapeutischen Verfahren als wissenschaftlich

Ohne Zusammenfassung     

Does quantity matter to a stingless bee?

Animal Cognition - Quantitative information is omnipresent in the world and a wide range of species has been shown to use quantities to optimize their decisions. While most studies have focused on...     

Coexistence of adjacent vacancy-ordered and eutectic phases in Al–Cu–Ni alloys

ABSTRACT

Copper-mould-cast Al–Cu–Ni alloys show adjacent coexistence of in situ grown ordered and eutectic phases. A bimodal microstructure of α–Al and eutectic α-Al+θ-Al₂Cu phases with length-scale hierarchy evolves during solidification. Microstructural analysis through Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) shows the presence of Vacancy-ordered phases (VOPs) with different morphologies in two different compositions.     

Physiological effects of enriched environment exposure and LTP induction in the hippocampus in vivo do not transfer faithfully to in vitro slices

A number of experimental paradigms use in vitro brain slices to test for changes in synaptic transmission and plasticity following a behavioral manipulation. For example, a number of previous studies have reported a variety of effects of environmental enrichment (EE) exposure on field potential responses in hippocampal slices, but in no study was is it known what changes had been elicited in vivo. In the present study, we recorded from the hippocampus in vivo while rats underwent a brief period of EE. There was no detectable EE-induced change in synaptic efficacy in the dentate gyrus in vivo, but there was an increase in cellular excitability. In slices prepared from the same animals, we failed to observe any evidence of the excitability increase. We next tested whether LTP induction in vivo was better preserved in vitro. However, when slices from these rats were examined, there was no observable change in perforant path synaptic strength, although there was a modest increase in excitability that correlated with the increased excitability observed in vivo. These findings suggest that synaptic changes induced in vivo either are not preserved faithfully or are difficult to detect in hippocampal slices, while changes in cellular excitability are better preserved.Exposure to an enriched environment (EE) can improve performance on a variety of hippocampus-dependent memory tasks in both normal (Kempermann et al. 1997; Duffy et al. 2001; Teather et al. 2002; Schrijver et al. 2004; Irvine and Abraham 2005) and disease model (Ohlsson and Johansson 1995; Young et al. 1999; Jankowsky et al. 2005; Lazarov et al. 2005; Nithianantharajah and Hannan 2006; Laviola et al. 2008) animals. Previous studies attempting to understand the physiological changes that mediate these effects have yielded mixed results, which may in part be due to the variability in enrichment paradigms used in different laboratories, but which may also be due to the method used to measure hippocampal physiology.Traditionally, researchers have studied the effects of EE using ex vivo brain slices. Such studies have sometimes reported an increase in synaptic strength following enrichment (Green and Greenough 1986; Foster et al. 1996; Foster and Dumas 2001), but a lack of a change has also been observed (Duffy et al. 2001; Feng et al. 2001; Parsley et al. 2007). The ex vivo approach is predicated on the assumption that EE (or other behavioral) treatment induces changes in neural function that are of sufficient magnitude and extent that they will still be present when the brain is removed and studied in vitro. However, there could be many hidden effects of slice preparation (Kirov et al. 2004) that change or obscure effects occurring in vivo.In a previous study, we were surprised to find few effects of a 3-mo EE treatment on hippocampal synaptic function and plasticity when assessed in vitro (Eckert et al. 2010), despite our having observed with in vivo recordings substantial effects with shorter periods of EE exposure (Irvine and Abraham 2005; Irvine et al. 2006). We therefore considered the possibility that effects measured electrophysiologically in vivo may not be readily detectable in vitro. Testing this hypothesis requires studying the same animals in vivo and in vitro, a control procedure we are not aware of having been reported previously in the literature. In the present study, we examined whether the effects of EE or LTP induction in vivo could be detected in hippocampal slices taken from the same animals. We failed to detect any of the in vivo changes, except for a modest increase in cellular excitability following LTP.     

Daily Behavior Report Cards and Systematic Direct Observation: An Investigation of the Acceptability,Reported Training and Use,and Decision Reliability Among School Psychologists

More than ever, educators require assessment procedures and instrumentation that are technically adequate as well as efficient to guide data-based decision making. Thus, there is a need to understand perceptions of available tools, and the decisions made when using collected data, by the primary users of those data. In this paper, two studies that surveyed members of the National Association of School Psychologists with regard to two procedures useful in formative assessment, (i.e., Daily Behavior Report Cards; Systematic Direct Observation), are presented. Participants reported greater overall levels of training and use of Systematic Direct Observation than Daily Behavior Report Cards, yet both techniques were rated as equally acceptable for use in formative assessment. Furthermore, findings supported that school psychologists tend to make similar intervention decisions when presented with both types of data. Implications, limitations, and future directions are discussed.     

An Experimental Analysis of Mathematics Instructional Components: Examining the Effects of Student-Selected Versus Empirically-Selected Interventions

Within the context of an experimental analysis, the current study examined the effects of student- and empirically-selected interventions on the mathematics computational fluency of three elementary-aged students. For all of the participants, the empirically-selected intervention resulted in higher levels of computational fluency then the student-selected intervention. These results suggest that empirically-selected interventions may enhance the mathematics computational fluency of students experiencing mathematics problems. However, individual responsiveness to empirically-selected interventions suggests the importance of conducting brief experimental analyses to determine the most efficacious intervention. The implication of these results for intervention selection and incorporating choice-making opportunities into academic interventions are discussed.