cFos Ensembles in the Dentate Gyrus Rapidly Segregate Over Time and do not Form a Stable Map of Space

Mice require several days of training to master the water maze, a spatial memory task for rodents. The hippocampus plays a key role in the formation of spatial and episodic memories, a process that involves the activation of immediate-early genes such as cFos. We trained cFos-reporter mice in the water maze, expecting that consistent spatial behavior would be reflected by consistent cFos patterns across training episodes. Even after extensive training, however, different sets of dentate gyrus (DG) granule cells were activated every day. Suppressing activity in the original encoding ensemble helped mice to learn a novel platform position (reversal learning). Our results suggest that even in a constant environment, cFos+ ensembles in the dorsal DG segregate as a function of time, but become partially reactivated when animals try to access memories of past events.

cFos ensembles in the dentate gyrus rapidly segregate over time and do not form a stable map of space

SummaryMice require several days of training to master the water maze, a spatial memory task for rodents. The hippocampus plays a key role in the formation of spatial and episodic memories, a process that involves the activation of immediate-early genes such as cFos. We trained cFos-reporter mice in the water maze, expecting that consistent spatial behavior would be reflected by consistent cFos patterns across training episodes. Even after extensive training, however, different sets of dentate gyrus (DG) granule cells were activated every day. Suppressing activity in the original encoding ensemble helped mice to learn a novel platform position (reversal learning). Our results suggest that even in a constant environment, cFos+ ensembles in the dorsal DG segregate as a function of time, but become partially reactivated when animals try to access memories of past events.

From Universal Classification to a Postcoordinated Universe

This chapter starts off from standard takes on knowledge organization and classification in libraries and encyclopedias, but then zeros in on the field of information retrieval, which develops in fundamental opposition to even the most visionary of library techniques. Coordinate indexing, the first technique in this lineage, is explicitly designed to eliminate the influence of librarians and other knowledge mediators by shifting expressive power from the classification system to the query and, by extension, to the information seeker. Order is no longer understood as a stable map to the universe of knowledge but increasingly as the outcome of a dynamic and purpose-driven process of ordering. The chapter closes by discussing coordinate indexing as a precursor of the relational model for database management.

A Boltzmann Approach to Percolation on Random Triangulations

We study the percolation model on Boltzmann triangulations using a generating function approach. More precisely, we consider a Boltzmann model on the set of finite planar triangulations, together with a percolation configuration (either site-percolation or bond-percolation) on this triangulation. By enumerating triangulations with boundaries according to both the boundary length and the number of vertices/edges on the boundary, we are able to identify a phase transition for the geometry of the origin cluster. For instance, we show that the probability that a percolation interface has length$n$decays exponentially with$n$except at a particular value$p_{c}$of the percolation parameter$p$for which the decay is polynomial (of order$n^{-10/3}$). Moreover, the probability that the origin cluster has size$n$decays exponentially if$p<p_{c}$and polynomially if$p\geqslant p_{c}$.The critical percolation value is$p_{c}=1/2$for site percolation, and$p_{c}=(2\sqrt{3}-1)/11$for bond percolation. These values coincide with critical percolation thresholds for infinite triangulations identified by Angel for site-percolation, and by Angel and Curien for bond-percolation, and we give an independent derivation of these percolation thresholds.Lastly, we revisit the criticality conditions for random Boltzmann maps, and argue that at$p_{c}$, the percolation clusters conditioned to have size$n$should converge toward the stable map of parameter$\frac{7}{6}$introduced by Le Gall and Miermont. This enables us to derive heuristically some new critical exponents.

Approximation of additive functional equations in NA Lie C*-algebras

In this paper, by using fixed point method, we approximate a stable map of higher *-derivation in NA C*-algebras and of Lie higher *-derivations in NA Lie C*-algebras associated with the following additive functional equation,where m ≥ 2.

Stable maps of genus zero in the space of stable vector bundles on a curve

Let [Formula: see text] be a smooth projective curve with genus [Formula: see text]. Let [Formula: see text] be the moduli space of stable rank two vector bundles on [Formula: see text] with a fixed determinant [Formula: see text] for [Formula: see text]. In this paper, as a generalization of Kiem and Castravet’s works, we study the stable maps in [Formula: see text] with genus [Formula: see text] and degree [Formula: see text]. Let [Formula: see text] be a natural closed subvariety of [Formula: see text] which parametrizes stable vector bundles with a fixed subbundle [Formula: see text] for a line bundle [Formula: see text] on [Formula: see text]. We describe the stable map space [Formula: see text]. It turns out that the space [Formula: see text] consists of two irreducible components. One of them parameterizes smooth rational cubic curves and the other parameterizes the union of line and smooth conics.

The Reeb Graph of a Map Germ from ℝ3 to ℝ2 with Isolated Zeros

We consider finitely determined map germs f : (ℝ3, 0) → (ℝ2, 0) with f–1(0) = {0} and we look at the classification of this kind of germ with respect to topological equivalence. By Fukuda's cone structure theorem, the topological type of f can be determined by the topological type of its associated link, which is a stable map from S2 to S1. We define a generalized version of the Reeb graph for stable maps γ : S2→ S1, which turns out to be a complete topological invariant. If f has corank 1, then f can be seen as a stabilization of a function h0: (ℝ2, 0) → (ℝ, 0), and we show that the Reeb graph is the sum of the partial trees of the positive and negative stabilizations of h0. Finally, we apply this to give a complete topological description of all map germs with Boardman symbol Σ2, 1.

Clinton ad buys bet on a stable US electoral map

Headline UNITED STATES: Clinton ad buys bet on stable map