Dma/RNF8 proteins are evolutionarily conserved E3 ubiquitin ligases that target septins.

PublishedJournal ArticleResearch Support, Non-U.S. Gov'tThe budding yeast proteins Dma1 and Dma2 are members of the unique FHA-RING domain protein family and are linked to mitotic regulation and septin organization by ill-defined mechanisms. We show that Dma2 has ubiquitin ligase activity, and that septins Shs1 and Cdc11 are likely direct in vivo targets. We further propose that human RNF8, rather than Chfr, is the mammalian Dma homolog. As in yeast, RNF8 localizes to the centrosomes and cell division sites and promotes ubiquitylation of the septin SEPT7, whose depletion increases cell division anomalies. Together, these findings reveal evolutionary and functional conservation of Dma proteins, and suggest that RNF8 maintains genome stability through independent, yet analogous, nuclear and cytoplasmic ubiquitylation activities.HFSP fellowshipCRUKERCEuropean Community’s Seventh Framework ProgramWellcome Trus

A method for dense packing discovery

The problem of packing a system of particles as densely as possible is foundational in the field of discrete geometry and is a powerful model in the material and biological sciences. As packing problems retreat from the reach of solution by analytic constructions, the importance of an efficient numerical method for conducting \textit{de novo} (from-scratch) searches for dense packings becomes crucial. In this paper, we use the \textit{divide and concur} framework to develop a general search method for the solution of periodic constraint problems, and we apply it to the discovery of dense periodic packings. An important feature of the method is the integration of the unit cell parameters with the other packing variables in the definition of the configuration space. The method we present led to improvements in the densest-known tetrahedron packing which are reported in [arXiv:0910.5226]. Here, we use the method to reproduce the densest known lattice sphere packings and the best known lattice kissing arrangements in up to 14 and 11 dimensions respectively (the first such numerical evidence for their optimality in some of these dimensions). For non-spherical particles, we report a new dense packing of regular four-dimensional simplices with density $\phi=128/219\approx0.5845$ and with a similar structure to the densest known tetrahedron packing.Comment: 15 pages, 5 figure

RNF8 links nucleosomal and cytoskeletal ubiquitylation of higher order protein structures.

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Global convergence of a non-convex Douglas-Rachford iteration

We establish a region of convergence for the proto-typical non-convex Douglas-Rachford iteration which finds a point on the intersection of a line and a circle. Previous work on the non-convex iteration [2] was only able to establish local convergence, and was ineffective in that no explicit region of convergence could be given

Hamiltonians separable in cartesian coordinates and third-order integrals of motion

We present in this article all Hamiltonian systems in E(2) that are separable in cartesian coordinates and that admit a third-order integral, both in quantum and in classical mechanics. Many of these superintegrable systems are new, and it is seen that there exists a relation between quantum superintegrable potentials, invariant solutions of the Korteweg-De Vries equation and the Painlev\'e transcendents.Comment: 19 pages, Will be published in J. Math. Phy

Fundamental limitations on "warp drive" spacetimes

"Warp drive" spacetimes are useful as "gedanken-experiments" that force us to confront the foundations of general relativity, and among other things, to precisely formulate the notion of "superluminal" communication. We verify the non-perturbative violation of the classical energy conditions of the Alcubierre and Natario warp drive spacetimes and apply linearized gravity to the weak-field warp drive, testing the energy conditions to first and second order of the non-relativistic warp-bubble velocity. We are primarily interested in a secondary feature of the warp drive that has not previously been remarked upon, if it could be built, the warp drive would be an example of a "reaction-less drive". For both the Alcubierre and Natario warp drives we find that the occurrence of significant energy condition violations is not just a high-speed effect, but that the violations persist even at arbitrarily low speeds. An interesting feature of this construction is that it is now meaningful to place a finite mass spaceship at the center of the warp bubble, and compare the warp field energy with the mass-energy of the spaceship. There is no hope of doing this in Alcubierre's original version of the warp-field, since by definition the point in the center of the warp bubble moves on a geodesic and is "massless". That is, in Alcubierre's original formalism and in the Natario formalism the spaceship is always treated as a test particle, while in the linearized theory we can treat the spaceship as a finite mass object. For both the Alcubierre and Natario warp drives we find that even at low speeds the net (negative) energy stored in the warp fields must be a significant fraction of the mass of the spaceship.Comment: 18 pages, Revtex4. V2: one reference added, some clarifying comments and discussion, no physics changes, accepted for publication in Classical and Quantum Gravit

Two-dimensional superintegrable metrics with one linear and one cubic integral

We describe all local Riemannian metrics on surfaces whose geodesic flows are superintegrable with one integral linear in momenta and one integral cubic in momenta. We also show that some of these metrics can be extended to the 2-sphere. This gives us new examples of Hamiltonian systems on the sphere with integrals of degree three in momenta, and the first examples of superintegrable metrics of nonconstant curvature on a closed surfaceComment: 35 page

Assessment of Trans-Environmental Transitions of Heavy Metals and Arsenic in Herbal Drugs and Herbal Medicinal Products of Valerian Rhizomes with Roots and Motherwort Herb

Scientific relevance. In the context of pharmacopoeial harmonisation, the available methods for quantifying the total heavy metal content in tinctures are not sufficient to demonstrate the safety of liquid dosage forms based on herbal drugs. However, the establishment of individual limits for the heavy metal content requires analysing the patterns of environmental toxicant transitions from plant raw materials to herbal medicinal products in finished dosage forms.Aim. This study aimed to analyse the trans-environmental transitions of heavy metals and arsenic from the soil through plants to herbal medicinal products using a case study of aqueous and alcoholic extracts of valerian and motherwort herbal drugs.Materials and methods. The study focused on motherwort herb and valerian rhizomes with roots, the corresponding herbal medicinal products, and the rhizospheric soil. The elemental composition of the studied samples was determined by inductively coupled plasma mass spectrometry.Results. The authors determined the content of 15 elements (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Sr, Cd, Sb, Hg, and Pb) in plant raw materials, the rhizosphere, and herbal drug infusions and tinctures. The concentrations of elements were 0.002–109.884 mg/kg in motherwort herb samples and 0.017–866.618 mg/kg in the samples of valerian rhizomes with roots. Pb, Cd, and As were detected in all plant raw materials, while Hg was found only in 25% of the study samples. The content of these elements was within acceptable limits. Valerian and motherwort infusions contained all elements, except for Hg; valerian tinctures were free from Fe and Hg; and motherwort tinctures included no Fe, Hg, Sr, Cd, and Pb. The concentrations of elements in the infusions did not exceed 3.169 mg/kg, while the concentrations of elements in the tinctures were below 1.27 mg/kg. In the tinctures, Zn, Cu, Mg, and Ti were the most abundant elements, and Sb and Cd were present in minimum amounts.Conclusions. Valerian and motherwort plants can concentrate Cu, Cr, Fe, and V from the soil. The transition of heavy metals and arsenic into infusions did not exceed 65% of the content of these elements in herbal drugs, while tinctures contained less than 30% of the content of heavy metals and arsenic in herbal drugs. Some elements passed into infusions 1.5–5 times more efficiently than into tinctures

Length and Redundancy in Health Care Providers; Speech During Interactions with Aphasic and Nonaphasic Persons

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Rate of Speech of Health Care Providers During Interactions with Aphasic and Nonaphasic Individuals

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