Preoperative Skin Conditioning: Extracellular Matrix Clearance and Skin Bed Preparation, A New Paradigm.

This paper introduces the concept of "skin bed preparation" prior to surgical procedures. Following the theory of chronic wound bed preparation and adapting the skin model to one of chronic wound changes related to extrinsic and intrinsic factors, a topical formulation aimed at recycling the extracellular matrix (ECM) from accumulated waste products is evaluated and discussed. The clearance of these products and stimulation of new replacements has the potential to change the regenerative milieu of the skin so that when procedures are carried out, cellular signaling and cross-talk at the dermal level are improved and healing is optimized. By introducing a combination of peptides and other synergistic active agents, a sequence of clearance, regeneration, and remodeling is initiated. This is confirmed and validated by a series of biopsies and clinical studies that demonstrate changes in the ECM as early as 2 to 3 weeks after application. Clinical studies related to resurfacing procedures show accelerated healing and improved symptomatic relief compared with standard of care by preconditioning the skin 2 weeks prior to the procedure. A similar approach is suggested as a potential advantage for invasive surgical procedures based on similar scientific principles elucidated on in the text

Surgery description of colored knots

The pair (K,r) consisting of a knot K and a surjective map r from the knot group onto a dihedral group is said to be a p-colored knot. D. Moskovich conjectured that for any odd prime p there are exactly p equivalence classes of p-colored knots up to surgery along unknots in the kernel of the coloring. We show that there are at most 2p equivalence classes. This is a vast improvement upon the previous results by Moskovich for p=3, and 5, with no upper bound given in general. T. Cochran, A. Gerges, and K. Orr, in "Dehn surgery equivalence relations of 3-manifolds", define invariants of the surgery equivalence class of a closed 3-manifold M in the context of bordisms. By taking M to be 0-framed surgery of the 3-sphere along K we may define Moskovich's colored untying invariant in the same way as the Cochran-Gerges-Orr invariants. This bordism definition of the colored untying invariant will be then used to establish the upper bound.Comment: 41 pages, 23 figures (Version 3) Minor revisions and typos fixed. Proofs of Propositions 4.1 and 4.8 revise

Ground State Phases of the Doped 4-Leg t-J Ladder

Using density matrix renormalization group techniques, we have studied the ground state of the 4-leg t-J ladder doped near half-filling. Depending upon J/t and the hole doping x, three types of ground state phases are found: (1) a phase containing d_{x^2-y^2} pairs; (2) a striped CDW domain-wall phase, and (3) a phase separated regime. A CDW domain-wall consists of fluctuating hole pairs and this phase has significant d_{x^2-y^2} pair field correlations.Comment: 10 pages, with 6 Postscript figure

d_{x^2-y^2} Pair Domain Walls

Using the density matrix renormalization group, we study domain wall structures in the t-J model at a hole doping of x=1/8. We find that the domain walls are composed of d_{x^2-y^2} pairs and that the regions between the domain walls have antiferromagnetic correlations that are pi phase shifted across a domain wall. At x=1/8, the hole filling corresponds to one hole per two domain wall unit cells. When the pairs in a domain wall are pinned by an external field, the d_{x^2-y^2} pairing response is suppressed, but when the pinning is weakened, d_{x^2-y^2} pair-field correlations can develop.Comment: 11 pages, with 3 Postscript figure

Limits on the Halo White Dwarf Component of Baryonic Dark Matter from the {\em Hubble Deep Field}

The MACHO collaboration lensing event statistics suggest that a significant fraction of the dark galactic halo can be comprised of baryonic matter in the form of white dwarf stars with masses between 0.1 and 1.0 \Msun . Such a halo white dwarf population, in order to have escaped detection by those who observe the white dwarf luminosity function of the disk, must have formed from an old population. The observations indicate that the number of halo white dwarfs per cubic parsec per unit bolometric magnitude is less than $10^{-5}$ at $10^{-4.5}$\Lsun; the number must rise significantly at lower luminosities to provide the needed baryonic halo mass. Such white dwarfs may easily escape detection in most current and earlier surveys. Though it is limited in angular extent, the {\em Hubble Deep Field} (HDF) probes a sufficient volume of the galactic halo to provide interesting limits on the number of halo white dwarf stars, and on the fraction of the halo mass that they can make up. If the HDF field can be probed for stars down to $V=29.8$ then the MACHO result suggests that there could be up to 12 faint halo white dwarfs visible in the HDF. Finding (or not finding) these stars in turn places interesting constraints on star formation immediately following the formation of the galaxy.Comment: 10 pages, AASTEX, 1 table, no figures, accepted for publication in Ap.J. Letter

Checkerboard patterns in the t-J model

Using the density matrix renormalization group, we study the possibility of real space checkerboard patterns arising as the ground states of the t-J model. We find that checkerboards with a commensurate (pi,pi) background are not low energy states and can only be stabilized with large external potentials. However, we find that striped states with charge density waves along the stripes can form approximate checkerboard patterns. These states can be stabilized with a very weak external field aligning and pinning the CDWs on different stripes.Comment: 4 pages, 5 figure