Global atmospheric budget of acetaldehyde: 3-D model analysis and constraints from in-situ and satellite observations

We construct a global atmospheric budget for acetaldehyde using a 3-D model of atmospheric chemistry (GEOS-Chem), and use an ensemble of observations to evaluate present understanding of its sources and sinks. Hydrocarbon oxidation provides the largest acetaldehyde source in the model (128 Tg a<sup>−1</sup>, a factor of 4 greater than the previous estimate), with alkanes, alkenes, and ethanol the main precursors. There is also a minor source from isoprene oxidation. We use an updated chemical mechanism for GEOS-Chem, and photochemical acetaldehyde yields are consistent with the Master Chemical Mechanism. We present a new approach to quantifying the acetaldehyde air-sea flux based on the global distribution of light absorption due to colored dissolved organic matter (CDOM) derived from satellite ocean color observations. The resulting net ocean emission is 57 Tg a<sup>−1</sup>, the second largest global source of acetaldehyde. A key uncertainty is the acetaldehyde turnover time in the ocean mixed layer, with quantitative model evaluation over the ocean complicated by known measurement artifacts in clean air. Simulated concentrations in surface air over the ocean generally agree well with aircraft measurements, though the model tends to overestimate the vertical gradient. PAN:NO<sub>x</sub> ratios are well-simulated in the marine boundary layer, providing some support for the modeled ocean source. We introduce the Model of Emissions of Gases and Aerosols from Nature (MEGANv2.1) for acetaldehyde and ethanol and use it to quantify their net flux from living terrestrial plants. Including emissions from decaying plants the total direct acetaldehyde source from the land biosphere is 23 Tg a<sup>−1</sup>. Other terrestrial acetaldehyde sources include biomass burning (3 Tg a<sup>−1</sup>) and anthropogenic emissions (2 Tg a<sup>−1</sup>). Simulated concentrations in the continental boundary layer are generally unbiased and capture the spatial gradients seen in observations over North America, Europe, and tropical South America. However, the model underestimates acetaldehyde levels in urban outflow, suggesting a missing source in polluted air. Ubiquitous high measured concentrations in the free troposphere are not captured by the model, and based on present understanding are not consistent with concurrent measurements of PAN and NO<sub>x</sub>: we find no compelling evidence for a widespread missing acetaldehyde source in the free troposphere. We estimate the current US source of ethanol and acetaldehyde (primary + secondary) at 1.3 Tg a<sup>−1</sup> and 7.8 Tg a<sup>−1</sup>, approximately 60{%} and 480% of the corresponding increases expected for a national transition from gasoline to ethanol fuel

The Relationship Between Black Hole Mass and Velocity Dispersion in Seyfert 1 Galaxies

Black hole masses in active galactic nuclei (AGN) are difficult to measure using conventional dynamical methods, but can be determined using the technique of reverberation mapping. However, it is important to verify that the results of these different methods are equivalent. This can be done indirectly, using scaling relations between the black hole and the host galaxy spheroid. For this purpose, we have obtained new measurements of the bulge stellar velocity dispersion, sigma, in Seyfert 1 galaxies. These are used in conjunction with the M_bh -- sigma relation to validate nuclear black hole masses, M_bh, in active galaxies determined through reverberation mapping. We find that Seyfert galaxies follow the same M_bh -- sigma relation as non-active galaxies, indicating that reverberation mapping measurements of M_bh are consistent with those obtained using other methods. We also reconsider the relationship between bulge absolute magnitude, M_bulge, and black hole mass. We find that Seyfert galaxies are offset from non-active galaxies, but that the deviation can be entirely understood as a difference in bulge luminosity, not black hole mass; Seyfert hosts are brighter than normal galaxies for a given value of their velocity dispersion, perhaps as a result of younger stellar populations.Comment: 12 pages, 8 figures, accepted for publication in the Astrophysical Journa

Differences in Relative Hippocampus Volume and Number of Hippocampus Neurons among Five Corvid Species

The relative size of the avian hippocampus (Hp) has been shown to be related to spatial memory and food storing in two avian families, the parids and corvids. Basil et al. [Brain Behav Evol 1996;47: 156-164] examined North American food-storing birds in the corvid family and found that Clark’s nutcrackers had a larger relative Hp than pinyon jays and Western scrub jays. These results correlated with the nutcracker’s better performance on most spatial memory tasks and their strong reliance on stored food in the wild. However, Pravosudov and de Kort [Brain Behav Evol 67 (2006), 1-9] raised questions about the methodology used in the 1996 study, specifically the use of paraffin as an embedding material and recalculation for shrinkage. Therefore, we measured relative Hp volume using gelatin as the embedding material in four North American species of food-storing corvids (Clark’s nutcrackers, pinyon jays, Western scrub jays and blue jays) and one Eurasian corvid that stores little to no food (azure-winged magpies). Although there was a significant overall effect of species on relative Hp volume among the five species, subsequent tests found only one pairwise difference, blue jays having a larger Hp than the azure-winged magpies. We also examined the relative size of the septum in the five species. Although Shiflett et al. [J Neurobiol 51 (2002), 215-222] found a difference in relative septum volume amongst three species of parids that correlated with storing food, we did not find significant differences amongst the five species in relative septum. Finally, we calculated the number of neurons in the Hp relative to body mass in the five species and found statistically significant differences, some of which are in accord with the adaptive specialization hypothesis and some are not

Differences in Relative Hippocampus Volume and Number of Hippocampus Neurons among Five Corvid Species

The relative size of the avian hippocampus (Hp) has been shown to be related to spatial memory and food storing in two avian families, the parids and corvids. Basil et al. [Brain Behav Evol 1996;47: 156-164] examined North American food-storing birds in the corvid family and found that Clark’s nutcrackers had a larger relative Hp than pinyon jays and Western scrub jays. These results correlated with the nutcracker’s better performance on most spatial memory tasks and their strong reliance on stored food in the wild. However, Pravosudov and de Kort [Brain Behav Evol 67 (2006), 1-9] raised questions about the methodology used in the 1996 study, specifically the use of paraffin as an embedding material and recalculation for shrinkage. Therefore, we measured relative Hp volume using gelatin as the embedding material in four North American species of food-storing corvids (Clark’s nutcrackers, pinyon jays, Western scrub jays and blue jays) and one Eurasian corvid that stores little to no food (azure-winged magpies). Although there was a significant overall effect of species on relative Hp volume among the five species, subsequent tests found only one pairwise difference, blue jays having a larger Hp than the azure-winged magpies. We also examined the relative size of the septum in the five species. Although Shiflett et al. [J Neurobiol 51 (2002), 215-222] found a difference in relative septum volume amongst three species of parids that correlated with storing food, we did not find significant differences amongst the five species in relative septum. Finally, we calculated the number of neurons in the Hp relative to body mass in the five species and found statistically significant differences, some of which are in accord with the adaptive specialization hypothesis and some are not

Evolution challenges. Integrating research and practice in teaching and learning about evolution

Abstract and Keywords Scientists frequently attribute public misunderstanding of evolution to religious or political influences. Ineffective undergraduate teaching has also contributed. Faculty often ignored strong pedagogical evidence. Five research conclusions are discussed: The traditional lecture approach is inadequate. Active learning is much more effective. Fundamental reasoning difficulties limit students' understanding. Simple steps help overcome these. Misconceptions typically persist unless directly addressed with a conceptual-change approach. Evolution is a complex set of ideas that cannot be adequately understood without advanced critical thinking. This is infrequently mastered without intentionally designed learning tasks. Understanding evolution is typically insufficient for its acceptance. But acceptance as valid for real-world decisions is important. This requires helping students consider social and affective factors related to evolution. Keywords: misconceptions, conceptual-change, intentional design, evolution acceptance Scientists frequently attribute the public misunderstanding of evolution largely to conservative religious influences or dubious political motivations. Indeed, Mazur (2004 found Christian religiosity to be the strongest correlate of "disbelief" in evolution with low educational attainment and political conservatism also important. How science is taught in undergraduate education is a powerful additional factor that usually has been ignored in analyses of Why Don't Undergraduates Really "Get" Evolution? What Can ... http://www.oxfordscholarship.com.ezproxy.lib.indiana.edu/vie... of 27 6/25/13 5:37 PM public misunderstanding of evolution. Rejection and misunderstanding of evolution are not simply the results of some facets of American culture. Rather, they are also the predictable results of traditional, didactic teaching strategies. Postsecondary science teaching often ignores strong evidence on ways to make instruction much more effective (e.g., The first part of this chapter focuses on four broadly applicable results of research on teaching undergraduate science. The latter part turns to strategies that take account of factors that apply more strongly to evolution than to much of the rest of science. Key Result 1: Active Learning Is More Effective Active learning substantially increases achievement when compared with traditional pedagogy in undergraduate science, a conclusion featured in a review in Science The inadequacy of the traditional lecture approach in undergraduate science has been demonstrated most extensively in physics, where active methods roughly doubled average normalized pretest to posttest gains in learning, an effect approximating a two standard deviation difference Thus, one answer to the question "What can faculty do to increase the proportion of students who 'get' evolution?" is to switch further toward structured active learning in lieu of more didactic pedagogies. The implications of this conclusion can be both distressing and elating. This conclusion can be distressing because time already spent on improving lectures would often have been spent much more effectively on improving pedagogy. The conclusion can be elating because changes can be fairly easy and can have large effects. Unfortunately, faculty often have reservations about adopting active learning. These reservations include loss of content coverage, possible loss of control over the class, and possible failure of the activities. Tanner (2009) addressed a number of these. Similarly, several dysfunctional illusions that falsely suggest a lack of rigor for more effective pedagogies probably have slowed their adoption However one chooses to label these reasoning abilities, scores on reasoning tests have often been shown to predict achievement in undergraduate science courses and, sometimes, in precollege science (e.g., These findings have profound implications for understanding and teaching molecular aspects of biology generally, and of evolution specifically, as shown by studies of undergraduate chemistry. For example, Herron (1975) listed startling differences between core ideas in chemistry that the concrete students can and cannot understand without altered pedagogy. These students will be a large fraction of any first-year class. (p.314) Scores on reasoning tests were also related to the acceptance of evolution. Students who scored lower on tests of basic reasoning were less likely to accept evolution on the pretest and were more likely to continue to reject evolution on the posttest than individuals who performed better on the reasoning assessment A major advance for understanding how differences in reasoning play out in learning biology was recently provided by 1. Descriptive predictions could be mastered by most students whatever their scores on reasoning tests. 2. Tasks requiring understanding and testing hypotheses involving perceptible causal agents (e.g., light, moisture) were usually mastered only by students with higher reasoning scores. 3. Tasks using hypotheses involving causal agents that cannot be as directly perceived (e.g., genetic versus environmental causation, chemical communication) were usually mastered only by students with even higher reasoning abilities. Much greater pedagogical support is needed for tasks requiring the use of causal hypotheses, especially those using inferred causal agents. These distinctions are fundamental to students' difficulties in understanding evolution and to the development of effective ways to help them master it. Unfortunately, the underlying reasoning patterns are not changed easily with conventional teaching. Other researchers have made additional suggestions for fostering more complex reasoning. For example, a nice example of the use of hands-on modeling to support more complex thinking in a large molecular biology class was provided by In summary, the answer to the question "What can faculty do to increase the proportion of students who 'get' evolution?" from this second perspective is that faculty often need to pay more attention to students' basic reasoning and to teach in ways that better support (rather than just require) scientific understanding and reasoning. Without such support many students cannot understand what is being taught even when they are trying quite hard to do so. Although these problems and many of the solutions have been clear for decades, they have not been widely adopted. "Because we [as faculty] are at the point that concrete experience … is superfluous, we tend to forget that it was not always so [for us] and in our rush to 'cover the material,' we omit the very kind of experiences that can make our subject meaningful to beginning students" (Herron, 1978, p. 167). Many faculty will be skeptical (as I was) that well-performing students are deficient in understanding the basic concepts that should underlie their successes in class. It may be hard to accept that even "facility in solving standard quantitative problems is not an adequate criterion for functional understanding" (Thornton, 1999). In order to see the limitations of current approaches and the effects of changes we need more sophisticated ways of writing in-class and exam assessments About the Index Search across all sources Show related links Why Don't Undergraduates Really "Get" Evolution? What Can ... http://www.oxfordscholarship.com.ezproxy.lib.indiana.edu/vie... of 27 6/25/13 5:37 PM macroevolution is central to an understanding of the strength of the evidence showing that evolution has occurred (Padian, 2010). Further, macroevolution "is perhaps the primary stumbling block" for students, teachers, and other adults who have difficulty accepting evolution (M. U. Smith, 2010b, p. 541). The switch in students' understanding from misconceptions or alternative conceptions to scientifically valid views is termed conceptual change (for evolution: Banet & Ayuso, 2003; Various approaches to teaching evolution have attempted to produce major conceptual change and understanding generally. M. U. Smith (2010b) provided a concise (p.317) overview. Six examples merit special discussion. Although these mostly address microevolution, they could be modified for topics in macroevolution. 1. An Exemplary Conceptual Change Approach. Banet and Ayuso About the Index Search across all sources Show related links Why Don't Undergraduates Really "Get" Evolution? What Can ... http://www.oxfordscholarship.com.ezproxy.lib.indiana.edu/vie... of 27 6/25/13 5:37 PM Roscoe, this volume). 5. Participatory Action Research. In a multiyear study, Grant (2008) examined the misconceptions his first-year biology students held about natural selection. "Many students who presented evidence on pre-tests that they harbored substantial misconceptions in fact remained highly resistant to instruction, and often defended their misconceptions using course appropriate terminology, but incorrectly, on the course final exam. In other words, many had hijacked course content in service of their misconceptions" (Grant, 2008, p. 15). He iteratively designed ways to address these in a large class setting. Key changes included repeatedly presenting summaries of in-class surveys of prior knowledge and misconceptions. He also asked students to discuss with their neighbors what evidence and arguments would be needed to foster the replacement of these misconceptions with expert knowledge. He termed this "participatory action research." It required substantial reductions in content and rearrangements of topics. There were large increases over previous years in the grades on the final examination questions on evolution: On a key question assessing natural selection, good answers (8 to10 of 10 points) increased from about 3% of students (2000)(2001)(2002)(2003)(2004)(2005) to 54% (2006)(2007), and very low scores (0-2 points) were eliminated. This approach has considerable promise for improving undergraduate science learning generally. Whole Course Transformation. In what is essentially a deep conceptual change approach, BioQUEST has emphasized computer-facilitated, case-based learning with a focus on problem-posing, problem-solving, and peer persuasion, often addressing topics in evolution In summary, the answer to the question "What can faculty do to increase the proportion of students who 'get' evolution?" from this third perspective is that faculty often need to give even more attention to students' persistent misunderstandings and to teach in ways that better support conceptual change (rather than falsely assuming that telling students the right idea or showing them the data will be sufficient to elicit change). Without explicit, active support for conceptual change, most students will retain their initial misunderstandings. (p.319) Key Result 4: Complex Thinking Is Requisite for Understanding Evolution Many of the difficulties we encounter in getting students to understand evolution are well explained by differences in their approaches to knowledge, specifically to how they expect to understand new topics. These approaches range from "just tell me what to memorize" to expecting us to help them understand the applications, implications, and trade-offs in various contexts. These different approaches are usefully understood as differences in adult cognitive development. There is a substantial body of research on cognitive development in college and its implications for learning and teaching. This approach began with Perry's (1970) study of "intellectual and ethical development" in undergraduates. Perry's work has been cited by hundreds of subsequent studies (partially reviewed by Cognitive development beyond that typically found in undergraduates is a prerequisite for an adequate understanding of evolution. Sinatra, Southerland, McConaughy, and Demastes About the Index Search across all sources Show related links Why Don't Undergraduates Really "Get" Evolution? What Can ... http://www.oxfordscholarship.com.ezproxy.lib.indiana.edu/vie... 6 of 27 6/25/13 5:37 PM they termed absolutism, relativism, and evaluativism. Perry's terms for these three approaches (dualism, multiplicity, and relativism) have been widely used, although some studies have used alternative terminologies. A simplified summary of these major cognitive differences will make clearer the implications for teaching evolution. (p.320) Absolutism (Perry's Dualism) About two-thirds of first-year students and half of sophomores had absolutism as their core approach Relativism (Perry's Multiplicity) When students first encounter meaningful uncertainty in a new area they typically have no idea how it might be resolved. In the face of uncertainty all opinions seem to be equally valid-any answer that one prefers on whatever grounds is fine. Personal experience, personally interpreted, has the preeminent role. This is the approach most of us usually use in picking a flavor of ice cream, but it is a terrible approach to critical thinking About one-third of first-year students and perhaps 80% of seniors were "transitional": they regarded knowledge in some areas as absolute and knowledge in others as uncertain and, hence, arbitrary Burgoyne and Downey (2011) have suggested that we ask students to see absolutism and relativism as two misconceptions: Contextual Knowing (Bendixen and Rule's Evaluativism; Perry's Relativism) The approach where students have learned to make context-framed, criteria-based comparisons has also been termed contextual relativism (e.g., Knefelkamp, 1999) (p.321) and contextual knowing As students become more cognitively sophisticated, they (like many older adults) typically use a mosaic of approaches, perhaps treating some topics in dualism/absolutism and some in multiplicity even while struggling to master contextual knowing in others Beyond Contextual Knowing The limitations of simple contextual knowing are evident when we consider complex problems. The core difficulty is that students who have learned to operate within a series of individual disciplines often have no coherent way to deal with differences that arise when a variety of disciplines apply to a complex problem. They consequently see any choice among combinations of disciplinary For example, even a local environmental issue, such as the appropriateness of a nuclear power plant, requires a consideration of trade-offs across multiple perspectives including science, waste disposal, environmental economics, politics, and environmental racism, to name just a few To deal with such issues constructively, students must learn to consider the benefits and negative consequences illuminated by each perspective. As students learn to make such analyses they begin thinking in a way that Perry termed "Commitment [within contextual relativism]" and Baxter Magolda termed "self-authorship." This approach is exceedingly rare among undergraduates except under transformed curricula Applications to Teaching Evolution "Perhaps the most useful developmental theory to be applied to evolution instruction is that of Perry" (M. U. Smith, 2010b, p. 541; also Nelson, 1986, etc.). Classroom applications that strive to foster cognitive development can profitably focus on key aspects of the three transitions between the four main approaches to understanding. (p.322) These are: initially understanding uncertainty, then using comparisons and criteria to address uncertainty (contextual knowing) and, later, using consequences and values to frame arguments and justify choices. Uncertainty in evolution can be invoked, for example, by listing (or having the class list) currently viable alternative hypotheses, listing ones that were historically viable or by asking for deep understanding of experimental designs (Why is this control included? Are any controls missing? What untested hypotheses might have produced the same results?). Once some important uncertainty has been made clear, the alternative hypotheses or design considerations or other factors need to be compared, and possibly resolved, using appropriate criteria. Unless both the alternatives and the criteria are made explicit, most of the critical thinking will be tacit and therefore incomprehensible-and the students' approaches to thinking will be unaffected. For comparisons of historically grounded alternatives in evolution, such as what sequences should have been expected from the fossil record, an appropriate criterion is the result of a fair test. A fair test is a new set of data that could have confirmed any of the alternatives and that is different from (and not tightly tied to) the data sets on which they were proposed. We can ask: What patterns of change in the fossil record might have been expected of the fossil record when the geological column was first put into its modern order in the 1840s, noting that evolution was not really available except to Darwin. Alternatives included: all kinds at the beginning with just extinction, Lyell's large cycles with great reptiles perhaps returning again (and again), Sedgwick's extinctions and new recreations, vertebrates first and invertebrates by degeneration, and, of course, evolution starting, as Darwin noted, with one or a few very simple kinds. Students will suggest some of these ideas, if asked. The fossil record itself provides a fair test of these alternatives, as most of them were not based on the ordered sequence of rocks in the newly emerging geological column and as any of the alternative patterns could have been found. A number of other criteria are also important. These include accounting for apparently conflicting scientific data and the availability of causal explanations (e.g., However, even when we understand that one alternative is much more probable than another we may choose not to accept it. It is often appropriate to reject hypotheses that are probably true when there are serious risks to accepting the hypothesis and being wrong. Thus, for many considerations of safety in the face of severe consequences we demand not just that safety be very probable but that it be overwhelmingly probable (basic decision theory, below). This requires moving beyond contextual knowing. For students studying evolution, going beyond contextual knowing would require that students understand the force of the evidence in the context of the nature of science generally; understand and know how to weigh the consequences (p.323) from the applications of evolution, both positive and negative; and understand how to fit evolution into larger cultural contexts. It thus becomes crucial for faculty members who teach evolution to help students address its consequences and applications. Faculty also need to consider whether to address the cultural contexts for evolution and, if so, how to do so effectively. About the Index Search across all sources Show related links Why Don't Undergraduates Really "Get" Evolution? What Can ... http://www.oxfordscholarship.com.ezproxy.lib.indiana.edu/vie... of 27 6/25/13 5:37 PM If we step back from focusing just on conceptual understanding or scientific reasoning, things become more complicated. Baxter Magolda (e.g., 2004a) noted that students make meaning of their experiences using their own perspectives rather than accepting the instructor's meaning and perspective. Further, the development of more complex ways of understanding is inextricably intertwined with the development of a different and more complex sense of self and of different and of more complex ways of relating to others. "Interviewees who developed complex ways of knowing [after graduation] often could not live those ways of knowing until they had developed complex ways of seeing themselves and their relations with others" (Baxter Magolda, 2004a, p. 39). Let me stress again the importance of making extensive use of structured active learning and not just because it fosters content mastery. Appropriately structured collaborative and cooperative learning also helps foster increased cognitive sophistication and the other changes that are essential to that cognitive development. I found two techniques to be especially powerful in fostering cognitive development: 1. In teaching evolution to seniors, I developed a worksheet based on Perry's descriptions of the cognitive tasks required for deep understanding (Nelson, 2010a), and had students complete the worksheet outside of class. Then, I implemented a whole-period discussion of applications of Perry's principles, a discussion that fostered deep rethinking with peers. 2. In courses ranging from first-year to graduate, I had the students either discuss excerpts from Perry's (1970) book including his summary of the student's experience (Nelson, 2010a) or presented and had them discuss and repeatedly refer back to a graphical synopsis of Perry (as in Nelson, 2010b). Using either approach, I repeatedly asked students how a person would respond to the evolution-creation controversy (and to other issues) from the perspective of an absolutist, versus from multiplicity, versus, in turn, from contextual knowing and, later, from self-authorship In summary, the answer to the question "What can faculty do to increase the proportion of students who 'get' evolution?" from this fourth perspective is that faculty need to design their courses to foster greater cognitive sophisticati

Breast Cancer DNA Methylation Profiles Are Associated with Tumor Size and Alcohol and Folate Intake

Although tumor size and lymph node involvement are the current cornerstones of breast cancer prognosis, they have not been extensively explored in relation to tumor methylation attributes in conjunction with other tumor and patient dietary and hormonal characteristics. Using primary breast tumors from 162 (AJCC stage I-IV) women from the Kaiser Division of Research Pathways Study and the Illumina GoldenGate methylation bead-array platform, we measured 1,413 autosomal CpG loci associated with 773 cancer-related genes and validated select CpG loci with Sequenom EpiTYPER. Tumor grade, size, estrogen and progesterone receptor status, and triple negative status were significantly (Q-values \u3c0.05) associated with altered methylation of 209, 74, 183, 69, and 130 loci, respectively. Unsupervised clustering, using a recursively partitioned mixture model (RPMM), of all autosomal CpG loci revealed eight distinct methylation classes. Methylation class membership was significantly associated with patient race (P\u3c0.02) and tumor size (P\u3c0.001) in univariate tests. Using multinomial logistic regression to adjust for potential confounders, patient age and tumor size, as well as known disease risk factors of alcohol intake and total dietary folate, were all significantly (P\u3c0.0001) associated with methylation class membership. Breast cancer prognostic characteristics and risk-related exposures appear to be associated with gene-specific tumor methylation, as well as overall methylation patterns

Game theory of mind

This paper introduces a model of ‘theory of mind’, namely, how we represent the intentions and goals of others to optimise our mutual interactions. We draw on ideas from optimum control and game theory to provide a ‘game theory of mind’. First, we consider the representations of goals in terms of value functions that are prescribed by utility or rewards. Critically, the joint value functions and ensuing behaviour are optimised recursively, under the assumption that I represent your value function, your representation of mine, your representation of my representation of yours, and so on ad infinitum. However, if we assume that the degree of recursion is bounded, then players need to estimate the opponent's degree of recursion (i.e., sophistication) to respond optimally. This induces a problem of inferring the opponent's sophistication, given behavioural exchanges. We show it is possible to deduce whether players make inferences about each other and quantify their sophistication on the basis of choices in sequential games. This rests on comparing generative models of choices with, and without, inference. Model comparison is demonstrated using simulated and real data from a ‘stag-hunt’. Finally, we note that exactly the same sophisticated behaviour can be achieved by optimising the utility function itself (through prosocial utility), producing unsophisticated but apparently altruistic agents. This may be relevant ethologically in hierarchal game theory and coevolution

M33: A Galaxy with No Supermassive Black Hole

Galaxies that contain bulges appear to contain central black holes whose masses correlate with the velocity dispersion of the bulge. We show that no corresponding relationship applies in the pure disk galaxy M33. Three-integral dynamical models fit Hubble Space Telescope WFPC2 photometry and STIS spectroscopy best if the central black hole mass is zero. The upper limit is 1500 M_sun. This is significantly below the mass expected from the velocity dispersion of the nucleus and far below any mass predicted from the disk kinematics. Our results suggest that supermassive black holes are associated only with galaxy bulges and not with their disks.Comment: 8 pages, AJ accepted, November issu