We study the complexity of the following cell connection and separation problems in segment arrangements. Given a set of straight-line segments in the plane and two points a and b in different cells of the induced arrangement: (i) compute the minimum number of segments one needs to remove so that there is a path connecting a to b that does not intersect any of the remaining segments; (ii) compu...

Any which way but loose back-to-back arrangement of kinetochores is not needed for correct alignment on the mitotic spindle, as shown by Hilary Dewar, Tomoyuki Tanaka (University of Dundee, UK), and colleagues. Sister chromatids are glued together by cohesin such that their kinetochores face opposing poles. This arrangement might thus prevent both chromatids from attaching to spindle microtubul...

The three-dimensional structure of the vertebrate skeletal muscle Z band reflects its function as the muscle component essential for tension transmission between successive sarcomeres. We have investigated this structure as well as that of the nearby I band in a normal, unstimulated mammalian skeletal muscle by tomographic three-dimensional reconstruction from electron micrograph tilt series of...

The title compound, [Al(H(2)O)(6)](CH(3)SO(3))(3) (common name: aluminium methane-sulfonate hexa-hydrate), was crystallized from an aqueous solution prepared by the precipitation reaction of aluminium sulfate and barium methane-sulfonate. Its crystal structure is the first of the boron group methane-sulfonates to be determined. The characteristic building block is a centrosymmetric unit contain...

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large panel precast structures are analyzed based on the connection rigidity. however, the connections undergo nonlinear and inelastic response, when subjected to seismic loads. thus, to study the actual behavior of structure, the connection nonlinearity should be implemented in the joints. in this paper, three conventional connection types are modeled based on the envelope of their cyclic resp...