Linear signaling in the Toll-Dorsal pathway of Drosophila: activated Pelle kinase specifies all threshold outputs of gene expression while the bHLH protein Twist specifies a subset

Differential activation of the Toll receptor leads to the formation of a broad Dorsal nuclear gradient that specifies at least three patterning thresholds of gene activity along the dorsoventral axis of precellular embryos. We investigate the activities of the Pelle kinase and Twist basic helix-loop-helix (bHLH) transcription factor in transducing Toll signaling. Pelle functions downstream of Toll to release Dorsal from the Cactus inhibitor. Twist is an immediate-early gene that is activated upon entry of Dorsal into nuclei. Transgenes misexpressing Pelle and Twist were introduced into different mutant backgrounds and the patterning activities were visualized using various target genes that respond to different thresholds of Toll-Dorsal signaling. These studies suggest that an anteroposterior gradient of Pelle kinase activity is sufficient to generate all known Toll-Dorsal patterning thresholds and that Twist can function as a gradient morphogen to establish at least two distinct dorsoventral patterning thresholds. We discuss how the Dorsal gradient system can be modified during metazoan evolution and conclude that Dorsal-Twist interactions are distinct from the interplay between Bicoid and Hunchback, which pattern the anteroposterior axis

Skein relations for Milnor's mu-invariants

The theory of link-homotopy, introduced by Milnor, is an important part of the knot theory, with Milnor's mu-bar-invariants being the basic set of link-homotopy invariants. Skein relations for knot and link invariants played a crucial role in the recent developments of knot theory. However, while skein relations for Alexander and Jones invariants are known for quite a while, a similar treatment of Milnor's mu-bar-invariants was missing. We fill this gap by deducing simple skein relations for link-homotopy mu-invariants of string links.Comment: Published by Algebraic and Geometric Topology at http://www.maths.warwick.ac.uk/agt/AGTVol5/agt-5-58.abs.htm

ACF estimation via difference schemes for a semiparametric model with mm-dependent errors

In this manuscript, we discuss a class of difference-based estimators of the autocovariance structure in a semiparametric regression model where the signal is discontinuous and the errors are serially correlated. The signal in this model consists of a sum of the function with jumps and an identifiable smooth function. A simpler form of this model has been considered earlier under the name of Nonparametric Jump Regression (NJRM). The estimators proposed allow us to bypass a complicated problem of prior estimation of the mean signal in such a model. We provide finite-sample expressions for biases and variance of the proposed estimators when the errors are Gaussian. Gaussianity in the above is only needed to provide explicit closed form expressions for biases and variances of our estimators. Moreover, we observe that the mean squared error of the proposed variance estimator does not depend on either the unknown smooth function that is a part of the mean signal nor on the values of difference sequence coefficients. Our approach also suggests sufficient conditions for $\sqrt{n}-$ consistency of the proposed estimators.Comment: 30 page

Morse theory of harmonic forms

We consider the problem of whether it is possible to improve the Novikov inequalities for closed 1-forms, or any other inequalities of a similar nature, if we assume, additionally, that the given 1-form is harmonic with respect to some Riemannian metric. We show that, under suitable assumptions, it is impossible. We use, in an essential way, a theorem of E.Calabi characterizing 1-forms which are harmonic with respect to some metric. We also study some interesting examples illustrating our results.Comment: 16 pages, AMSTex, 12 figure

What About BOEM? The Need to Reform the Regulations Governing Offshore Oil and Gas Planning and Leasing

The nature of offshore oil and gas activities is changing as companies are forced into difficult and remote areas, including the U.S. Arctic Ocean. As evidenced by the 2010 Deepwater Horizon tragedy and Shell\u27s error-plagued efforts to drill exploration wells in the Chukchi and Beaufort seas in 2012, the rules governing whether and under what conditions to allow offshore drilling in frontier areas have not kept pace with environmental and technical changes. These rules were implemented in 1979 and have remained substantively the same since. Recent changes to at the Department of the Interior to disband the Minerals Management Service, improve certain safety requirements, and move toward implementing Arctic-specific spill prevention and response requirements are important steps. Those changes, however, apply only after the decision to allow oil and gas activity has been made. Congress has not amended the governing statute, and the agency has not modified in any meaningful way the regulations that govern the initial processes through which it decides whether and under what circumstances to allow offshore oil and gas activities in a given area. This Article argues that the regulations that govern offshore oil and gas planning and leasing should be fundamentally revised to account for changes in the industry and agency, remedy broadly acknowledged deficiencies, and reflect new administrative policies. It also recommends a path to achieve the needed change

Properties of developmental gene regulatory networks

The modular components, or subcircuits, of developmental gene regulatory networks (GRNs) execute specific developmental functions, such as the specification of cell identity. We survey examples of such subcircuits and relate their structures to corresponding developmental functions. These relations transcend organisms and genes, as illustrated by the similar structures of the subcircuits controlling the specification of the mesectoderm in the Drosophila embryo and the endomesoderm in the sea urchin, even though the respective subcircuits are composed of nonorthologous regulatory genes

Are Investments in Daughters Lower When Daughters Move Away?

In much of the developing world daughters receive lower education and other investments than do their brothers, and may even be so devalued as to suffer differential mortality. Daughter disadvantage may be due in part to social norms that prescribe that daughters move away from their natal family upon marriage, a practice known as virilocality. We evaluate the effects of virilocality on female disadvantage using data from the Indonesia Family Life Survey. We find little support for the hypothesis. There is no evidence that the overall pattern of rough equality in the treatment of boys and girls in Indonesia masks differences according to post-marital residential practice. Virilocal groups do not have "missing daughters." Nor is there other evidence of son preference, such as in relatively low height for- age or education for girls and women in virilocal areas. Explanations of daughter disadvantage as due to virilocality should be subject to further scrutiny and contextualization.

The Contraction of Time and Space in Remote Chromosomal Interactions

Lucas et al. report the visualization of V(D)J recombination of the immunoglobulin heavy-chain gene (Igh) in living pro-B cells. Despite the huge distances separating V coding sequences from D-J sequences (∼2 Mb), the authors document an astonishingly rapid rate of remote associations. The key to speed is contraction of the Igh chromosomal domain. These findings provide a foundation for understanding long-range regulatory interactions in a variety of developmental processes, including the patterning of vertebrate limbs