Numbers, not value, motivate cooperation in humans and orangutans

Cooperation among competitors-whether sharing the burden of wind resistance in the Tour de France, forming price-fixing cartels in economic markets, or adhering to arms-control agreements in international treaties-seldom spreads in proportion to the potential benefits. To gain insight into the minds of uncooperative agents, economists and social psychologists have used the prisoner's dilemma task to examine factors leading to cooperation among competitors. Two types of factors have emerged in these studies: the relative rewards of defecting versus cooperating and breakdowns in trust, forgiveness and communication. The generalizability of economic and social psychological factors, however, relies on the assumption that agents' comparisons of gains and losses (whether for themselves, others, or both) preserves ratio information over arbitrary units, such as dollars and cents, and real rewards, such as food. This assumption is inconsistent with psychophysical studies on how the brain represents quantitative information, which suggests that mental magnitudes increase logarithmically with actual value. Thus, discrimination of two numerical magnitudes improves as the numerical distance between them increases and decreases as the magnitudes increase. Here we show an important consequence of this representational system for economic decision making: in the prisoner's dilemma game, purely nominal increases in the numerical magnitude of payoffs (such as, converting dollar values to cents or whole grapes into grape-parts) has a large effect on cooperative behaviour. Moreover, a logarithmic scaling of the ratio of rewards for cooperation versus defection predicted 97% of variability in observed cooperation, whereas the objective ratio predicted 0% of variability. By linking the brain's system of representing the magnitude of rewards to motivations for cooperative behaviour, these findings suggest that the nature of numerical representations may also account for the subjective value function described by Bernoulli, in which the apparent value of monetary incentives increases logarithmically with actual value

Observation of magnetism in Au thin films

Direct magnetization measurements of thin gold films are presented. These measurements integrate the signal from the thin film under study and the magnetic contribution of the film's interface with the substrate. The diamagnetic contribution to the signal from the bulk substrate is of the same order as the noise level. we find that thin gold films can exhibit positive magnetization. The character of their magnetic behavior is strongly substrate dependent.Comment: 9 pages, 4 figure

Conditions and Practices Associated with Teacher Professional Development and Its Impact on Instruction in TALIS 2013

A key lever for improving teaching is provision of effective professional development. This paper uses TALIS 2013 data to consider personal and school-level factors associated with teacher participation in effective professional development and reports of impact on instruction. Results of the analyses indicate that levels of teacher co-operation and instructionally-focused leadership in schools are associated with higher levels of effective professional development participation and reported instructional impact. Systems also vary significantly on the percentage of teachers in schools with supportive conditions and this is associated with differences in teacher participation in professional development types and reported instructional impact

Impact of Georgia's Pre-K Program on Kindergarten through Third Grade Teachers

The Georgia Prekindergarten Program (Pre-K), established in 1993, provides Georgia's fouryear-old children with high quality preschool experiences in order to prepare them for kindergarten. Immediate gains resulting from Pre-K can be lost if teachers in later grades are not prepared to capitalize on the increasing capabilities of students. To sustain the positive effects of the Pre-K program, teachers in later grades need both to recognize that students are better prepared for school and to adapt their instructional practices to take advantage of their students' increasing capabilities. Research implies that teachers adopt practices in their classrooms relative to how their beliefs match assumptions inherent in new programs. Thus, this study investigates teacher awareness of the impact of Pre-K on students, teacher beliefs about instructional practices, current instructional practices, and the relationship between beliefs and practices.The Council for School Performance launched this study to examine the implications of the Pre-K program for teachers of children in kindergarten through third grade. Through a survey of teachers in Georgia, the Council has found that teachers believe that the Pre-K program has positively affected students in elementary school, despite observations that students are, overall, changing for the worse. The majority of teachers believe in child-centered instructional practices, but this belief has not been adopted into their own instructional practices. Overall, teachers are as likely to use child-centered practices as they are to use teacher-directed activities

Complex Chebyshev polynomials on circular sectors

AbstractAll those complex Chebyshev polynomials on circular sectors are given explicitly for which the set of extremal points is a certain set E or a subset of E. The case where zn is the Chebyshev polynomial on a circular sector is completely characterized. Some graphs representing the absolute value and the argument of certain selected Chebyshev polynomials on circular sectors are presented, demonstrating in particular the heterogeneous behavior of best complex Chebyshev approximations

Probing the interaction forces of prostate cancer cells with collagen I and bone marrow derived stem cells on the single cell level.

Adhesion of metastasizing prostate carcinoma cells was quantified for two carcinoma model cell lines LNCaP (lymph node-specific) and PC3 (bone marrow-specific). By time-lapse microscopy and force spectroscopy we found PC3 cells to preferentially adhere to bone marrow-derived mesenchymal stem cells (SCP1 cell line). Using atomic force microscopy (AFM) based force spectroscopy, the mechanical pattern of the adhesion to SCP1 cells was characterized for both prostate cancer cell lines and compared to a substrate consisting of pure collagen type I. PC3 cells dissipated more energy (27.6 aJ) during the forced de-adhesion AFM experiments and showed significantly more adhesive and stronger bonds compared to LNCaP cells (20.1 aJ). The characteristic signatures of the detachment force traces revealed that, in contrast to the LNCaP cells, PC3 cells seem to utilize their filopodia in addition to establish adhesive bonds. Taken together, our study clearly demonstrates that PC3 cells have a superior adhesive affinity to bone marrow mesenchymal stem cells, compared to LNCaP. Semi-quantitative PCR on both prostate carcinoma cell lines revealed the expression of two Col-I binding integrin receptors, α1β1 and α2β1 in PC3 cells, suggesting their possible involvement in the specific interaction to the substrates. Further understanding of the exact mechanisms behind this phenomenon might lead to optimized therapeutic applications targeting the metastatic behavior of certain prostate cancer cells towards bone tissue

NMR Time Reversal Experiments in Highly Polarised Liquid 3He-4He Mixtures

Long-range magnetic interactions in highly magnetised liquids (laser-polarised 3He-4He dilute mixtures at 1 K in our experiment) introduce a significant non-linear and non-local contribution to the evolution of nuclear magnetisation that leads to instabilities during free precession. We recently demonstrated that a multi-echo NMR sequence, based on the magic sandwich pulse scheme developed for solid-state NMR, can be used to stabilise the magnetisation against the effect of distant dipolar fields. Here, we report investigations of echo attenuation in an applied field gradient that show the potential of this NMR sequence for spin diffusion measurements at high magnetisation densities.Comment: Accepted for publication in the Journal of Low Temperature Physic

The Interactive Effects of Sex of a Sender and Gender Role on Liking and Perceived Competence in Online Email Communication

The purpose of the present study was to examine how evaluations of an email sender would be influenced by gender role and sex of the sender. It was hypothesized that male senders would be liked more and perceived as more competent than females and that agentic male and communal female senders would be liked more and perceived as more competent than communal male and agentic female senders, respectively. Senders would also be ranked in the following order from most positive scores to least: agentic males, communal females, agentic females, communal males. Using a 2 (sex of participants: male vs female) x 2 (sex of the sender: male vs female) x 2 (gender role: agentic vs communal) between-subjects analysis of variance (ANOVA) and data from 150 college students, it was found that there was no effect of sex of the sender and gender role to support the first three hypotheses. However, communal senders were found to be liked more and perceived as more competent than agentic senders. The results of this study suggest that requests and other interactions online be written using communal language