De-Centering the Center: Postmodernism and Meaning

Future teachers should have…some workable philosophy regarding the nature of language

False discovery rate regression: an application to neural synchrony detection in primary visual cortex

Many approaches for multiple testing begin with the assumption that all tests in a given study should be combined into a global false-discovery-rate analysis. But this may be inappropriate for many of today's large-scale screening problems, where auxiliary information about each test is often available, and where a combined analysis can lead to poorly calibrated error rates within different subsets of the experiment. To address this issue, we introduce an approach called false-discovery-rate regression that directly uses this auxiliary information to inform the outcome of each test. The method can be motivated by a two-groups model in which covariates are allowed to influence the local false discovery rate, or equivalently, the posterior probability that a given observation is a signal. This poses many subtle issues at the interface between inference and computation, and we investigate several variations of the overall approach. Simulation evidence suggests that: (1) when covariate effects are present, FDR regression improves power for a fixed false-discovery rate; and (2) when covariate effects are absent, the method is robust, in the sense that it does not lead to inflated error rates. We apply the method to neural recordings from primary visual cortex. The goal is to detect pairs of neurons that exhibit fine-time-scale interactions, in the sense that they fire together more often than expected due to chance. Our method detects roughly 50% more synchronous pairs versus a standard FDR-controlling analysis. The companion R package FDRreg implements all methods described in the paper

Cosmic Neutrino Last Scattering Surface

Neutrinos decoupled from the rest of the cosmic plasma when the Universe was less than one second old, far earlier than the photons which decoupled at t=380,000 years. Surprisingly, though, the last scattering surface of the neutrinos is much closer to us than that of the photons. Here we calculate the properties of the last scattering surfaces of the three species of neutrinos.Comment: Important reference to earlier work of Bisnovatyi-Kogan and Seidov added, and mis-spelling of Opher reference correcte

Algebraic and combinatorial aspects of sandpile monoids on directed graphs

The sandpile group of a graph is a well-studied object that combines ideas from algebraic graph theory, group theory, dynamical systems, and statistical physics. A graph's sandpile group is part of a larger algebraic structure on the graph, known as its sandpile monoid. Most of the work on sandpiles so far has focused on the sandpile group rather than the sandpile monoid of a graph, and has also assumed the underlying graph to be undirected. A notable exception is the recent work of Babai and Toumpakari, which builds up the theory of sandpile monoids on directed graphs from scratch and provides many connections between the combinatorics of a graph and the algebraic aspects of its sandpile monoid. In this paper we primarily consider sandpile monoids on directed graphs, and we extend the existing theory in four main ways. First, we give a combinatorial classification of the maximal subgroups of a sandpile monoid on a directed graph in terms of the sandpile groups of certain easily-identifiable subgraphs. Second, we point out certain sandpile results for undirected graphs that are really results for sandpile monoids on directed graphs that contain exactly two idempotents. Third, we give a new algebraic constraint that sandpile monoids must satisfy and exhibit two infinite families of monoids that cannot be realized as sandpile monoids on any graph. Finally, we give an explicit combinatorial description of the sandpile group identity for every graph in a family of directed graphs which generalizes the family of (undirected) distance-regular graphs. This family includes many other graphs of interest, including iterated wheels, regular trees, and regular tournaments.Comment: v2: Cleaner presentation, new results in final section. Accepted for publication in J. Combin. Theory Ser. A. 21 pages, 5 figure

Biological Effects of Corynebacterium Parvum. III. amplification of resistance and impairment of Active Immunity to Murine Tumours

The effect of pre-treatment with Corynebacterium parvum on the growth in vivo of a range of experimental mouse tumours with differing characteristics has been investigated. Varying degrees of protection were observed which were generally greater with the more immunogenic tumours. Administration of C. parvum 7 days before immunization with irradiated tumour cells diminished the protective effect which could be obtained by immunization alone. The possible basis for these seemingly conflicting influences is considered

How Not to Invent a Patent Crisis

This short essay written for a broad audience addresses the problems that are at the center of current debates in academic and policy circles about the patent system. Most current patent reform proposals are designed to give officials and courts more power to weaken or eliminate ‘‘unworthy’’ patents and take primary aim at so-called patent trolls. This essay argues that in light of the rapid, and excessive, changes that have already occurred in the courts, what patent law needs is a tweaking of existing safety valves and processes - not opening the floodgates to more discretion and uncertainty

The Effects of Heading on Neurocognitive Function in Female Collegiate Soccer Players During an Entire Soccer Season

Recently, much debate has occurred regarding the effects of repeated heading by soccer players on their neurocognitive function. PURPOSE: To determine the effects of heading on neurocognitive function in female collegiate soccer players during an entire soccer season. METHODS: Twenty-four members of the 2012 Southwestern University Women’s Soccer team completed the ImPACT test during preseason and postseason, and self-reported the number of headers for the week immediately prior to each testing session. Amount of playing time for each player was determined from records obtained from the Southwestern University Athletics Department. The six composite scores and the cognitive efficiency index from the ImPACT test were measured in each session. Paired t tests were used to evaluate neurocognitive performance at each of the testing periods. Multiple regressions were run to compare the independent variables of playing time and number of headers to the seven ImPACT test composite scores from the preseason and postseason testing periods. RESULTS: There was an increase in visual motor speed, a decrease in reaction time, and an increase in cognitive efficiency from preseason to postseason (t(23) = -4.63, p \u3c 0.001), (t(23) = 2.17, p = 0.041), and (t(23) = -2.45, p = 0.022), respectively. During preseason, number of headers performed significantly predicted reaction time (F(1,22) = 5.37, p = 0.03), and explained approximately 20% of the variance in reaction time (r2 = 0.196). Number of headers performed significantly predicted cognitive efficiency (F(1,22) = 5.56, p = 0.03), and explained approximately 20% of the variance in cognitive efficiency (r2 = 0.202). During postseason, number of minutes played significantly predicted visual memory (F(1,22) = 4.71, p = 0.04), and explained approximately 18% of the variance in visual memory (r2 = 0.176). CONCLUSION: The changes in these neurocognitive variables from preseason to postseason indicated that athletes performed better postseason. The number of headers and the total playing time across one season appear to have had no negative effects on neurocognitive function in these soccer players

An all-optical approach for probing microscopic flows in living embryos

Living systems rely on fluid dynamics from embryonic development to adulthood. To visualize biological fluid flow, devising the proper labeling method compatible with both normal biology and in vivo imaging remains a major experimental challenge. Here, we describe a simple strategy for probing microscopic fluid flows in vivo that meets this challenge. An all-optical procedure combining femtosecond laser ablation, fast confocal microscopy and 3D-particle tracking was devised to label, image and quantify the flow. This approach is illustrated by studying the flow generated within a micrometer scale ciliated vesicle located deep inside the zebrafish embryo and involved in breaking left-right embryonic symmetry. By mapping the velocity field within the vesicle and surrounding a single beating cilium, we show this method can address the dynamics of cilia-driven flows at multiple length scales, and can validate the flow features as predicted from previous simulations. This approach provides new experimental access to questions of microscopic fluid dynamics in vivo