STANDARDS There is insufficient evidence to support treatment standards. GUIDELINES There is insufficient evidence to support treatment guidelines. OPTIONS Treatment of atlas-axis combination fractures based primarily on the specific characteristics of the axis fracture is recommended. External immobilization of most C1--C2 combination fractures is recommended. C1--Type II odontoid combinat...

Let Hn(z) be the function of a complex variable z defined by Hn(z) = ∑ G(±ia1 ± · · · ± ian)e iz(±b1±···±bn) where the summation is over all 2 possible plus and minus sign combinations, the same sign combination being used in both the argument of G and in the exponent. The numbers a1, a2, a3, . . . and b1, b2, b3, . . . are assumed to be positive, and G is an entire function of genus 0 or 1 tha...

We consider the quadratic eigenvalue problem (QEP) (λ2M + λG + K)x = 0, where M = MT is positive definite, K = KT is negative definite, and G = −GT . The eigenvalues of the QEP occur in quadruplets (λ, λ,−λ,−λ) or in real or purely imaginary pairs (λ,−λ). We show that all eigenvalues of the QEP can be found efficiently and with the correct symmetry, by finding a proper solvent X of the matrix e...

Embryonic axis formation in vertebrates is initiated by the establishment of the dorsal Nieuwkoop blastula organizer, marked by the nuclear accumulation of maternal b-catenin, a transcriptional effector of canonical Wnt signaling. Known regulators of axis specification include the canonical Wnt pathway components that positively or negatively affect bcatenin. An involvement of G-protein coupled...

The title tripeptide, C17H23N3O6, contains a nonproteinogenic C-terminal amino acid residue, norvaline, which is an isomer of the amino acid valine. Norvaline, unlike valine, has an unbranched side chain. The mol-ecule has a Gly-Gly segment which adopts an extended conformation. The norvaline residue also adopts an extended backbone conformation while its side chain has a g (+) t conformation. ...

Heterogeneous nucleation is vital to a wide range of areas as diverse as ice nucleation on atmospheric aerosols and the fabrication of high-performance thin films. There is excellent evidence that surface topography is a key factor in directing crystallization in real systems; however, the mechanisms by which nanoscale pits and pores promote nucleation remain unclear. Here, we use natural cleav...