Toroidal and Boundary-Reducing Dehn Fillings

Let M be a simple 3-manifold with a toral boundary component partial_0 M. If Dehn filling M along partial_0 M one way produces a toroidal manifold and Dehn filling M along partial_0 M another way produces a boundary-reducible manifold, then we show that the absolute value of the intersection number on partial_0 M of the two filling slopes is at most two. In the special case that the boundary-reducing filling is actually a solid torus and the intersection number between the filling slopes is two, more is said to describe the toroidal filling.Comment: 12 pp., AmSTeX, 6 figs.[uses epsf], Topology Appl. (to appear

Normal mass density of a superfluid Fermi gas at unitarity

We calculate the normal mass density of a paired Fermi gas at unitarity. The dominant contribution near the superfluid transition is from fermionic quasiparticle excitations, and is thus sensitive to the pairing gap. A comparison with the recent experiment of Sidorenkov et al. suggests that the superfluid gap near the transition temperature is larger than the BCS value, but the data do not permit a quantitative inference of the gap. Calculations of the quenched moment of inertia of a BCS superfluid in a harmonic trap are in reasonable agreement with the earlier experiment of Riedl et al.Comment: 6 pages, 2 figures, published versio

Objectual understanding, factivity and belief

Should we regard Jennifer Lackey’s (2007) ‘Creationist Teacher’ as understanding evolution, even though she does not, given her religious convictions, believe its central claims? We think this question raises a range of important and unexplored questions about the relationship between understanding, factivity and belief. Our aim will be to diagnose this case in a principled way, and in doing so, to make some progress toward appreciating what objectual understanding—i.e., understanding a subject matter or body of information—demands of us. Here is the plan. After some ground clearing in §1, §2 outlines and motivates a plausible working model—moderate factivity—for characterising the sense in which objectual understanding should be regarded as factive. §3 shows how the datum that we can understand false theories can, despite initial suggestions to the contrary, be assimilated straightforwardly within the moderate factivity model. §4 highlights how the inverse kind of case to that explored in §3—viz., a variant of Lackey’s creationist teacher case—poses special problems for moderate factivity. With reference to recent work on moral understanding by Hills (2009), §5 proposes a solution to the problem, and §6 attempts to diagnose why it is that we might originally have been led to draw the wrong conclusion

Knowledge, Assertion and Intellectual Humility

This paper has two central aims. First, we motivate a puzzle. The puzzle features four independently plausible but jointly inconsistent claims. One of the four claims is the sufficiency leg of the knowledge norm of assertion (KNA-S), according to which one is properly epistemically positioned to assert that p if one knows that p. Second, we propose that rejecting (KNA-S) is the best way out of the puzzle. Our argument to this end appeals to the epistemic value of intellectual humility in social-epistemic practice

Television noise reduction device

A noise reduction system that divides the color video signal into its luminance and chrominance components is reported. The luminance component of a given frame is summed with the luminance component of at least one preceding frame which was stored on a disc recorder. The summation is carried out so as to achieve a signal amplitude equivalent to that of the original signal. The averaged luminance signal is then recombined with the chrominance signal to achieve a noise-reduced television signal

Television noise-reduction device

System greatly improves signal-to-noise ratio with little or no loss in picture resolution. By storage of luminance component, which is summed with chrominance component, system performs mathematical integration of basically-repetitive television signals. Integration of signals over interval of their repetition causes little change in original signals and eliminates random noise

Googled Assertion

Recent work in the philosophy of mind and cognitive science (e.g., Clark and Chalmers 1998; Clark 2010a; Clark 2010b; Palermos 2014) can help to explain why certain kinds of assertions—made on the basis of information stored in our gadgets rather than in biological memory—are properly criticisable in light of misleading implicatures, while others are not

Bio-conversion of water hyacinths into methane gas, part 1

Bio-gas and methane production from the microbial anaerobic decomposition of water hyacinths (Eichhornia crassipes) (Mart) Solms was investigated. These experiments demonstrated the ability of water hyacinths to produce an average of 13.9 ml of methane gas per gram of wet plant weight. This study revealed that sample preparation had no significant effect on bio-gas and/or methane production. Pollution of water hyacinths by two toxic heavy materials, nickel and cadmium, increased the rate of methane production from 51.8 ml/day for non-contaminated plants incubated at 36 C to 81.0 ml/day for Ni-Cd contaminated plants incubated at the same temperature. The methane content of bio-gas evolved from the anaerobic decomposition of Ni-Cd contaminated plants was 91.1 percent as compared to 69.2 percent methane content of bio-gas collected from the fermentation of non-contaminated plants

FEDERAL GRAZING REFORM AND AVOIDABLE RISK

Recent rangeland reform attempts have increased ranchers'Â’ uncertainty of retaining grazing permits on federal land. This uncertainty is analyzed with a model of grazing on federal land. Ranchers facing this uncertainty will behave differently than if they were guaranteed the renewal of grazing permits at constant real grazing fees. It is shown that the socially optimal outcome may be achieved by adding avoidable risk through targeted rangeland reform. Rangeland reform attempts that create unavoidable risk can make both ranchers and environmental groups worse off.Agricultural and Food Policy,

Peer Effects in Higher Education

In this chapter, we describe the potential significance of student peer effects for the economic structure of and behavior in higher education. Their existence would motivate much of the restricted supply, student queuing, and selectivity and institutional competition via merit aid and honors colleges that we see in American higher education; their (appropriate) non-linearity could justify the resulting stratification of higher education as an efficient way to produce human capital. In addition, we use data from the College and Beyond entering class of 1989, combined with phonebook data identifying roommates, to implement a quasi-experimental empirical strategy aimed at measuring peer effects in academic outcomes. In particular, we use data on individual students' grades, SAT scores, and the SAT scores of their roommates at three schools to estimate the effect of roommates' academic characteristics on an individual's grades. The results suggest that, for two of the three schools used, students in the middle of the SAT distribution do somewhat worse in terms of grades if they share a room with a student who is in the bottom 15 percent of the SAT distribution. Students in the top of the SAT distribution appear often not to be affected by the SAT scores of their roommates. These results are similar to those reported in earlier research using data from Williams (Zimmerman) and Dartmouth (Sacerdote).