Ageing: collagenase‐mediated collagen fragmentation as a rejuvenation target

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108666/1/bjd13267.pd

Theory of Double-Sided Flux Decorations

A novel two-sided Bitter decoration technique was recently employed by Yao et al. to study the structure of the magnetic vortex array in high-temperature superconductors. Here we discuss the analysis of such experiments. We show that two-sided decorations can be used to infer {\it quantitative} information about the bulk properties of flux arrays, and discuss how a least squares analysis of the local density differences can be used to bring the two sides into registry. Information about the tilt, compressional and shear moduli of bulk vortex configurations can be extracted from these measurements.Comment: 17 pages, 3 figures not included (to request send email to [email protected]

The Electron Spectral Function in Two-Dimensional Fractionalized Phases

We study the electron spectral function of various zero-temperature spin-charge separated phases in two dimensions. In these phases, the electron is not a fundamental excitation of the system, but rather ``decays'' into a spin-1/2 chargeless fermion (the spinon) and a spinless charge e boson (the chargon). Using low-energy effective theories for the spinons (d-wave pairing plus possible N\'{e}el order), and the chargons (condensed or quantum disordered bosons), we explore three phases of possible relevance to the cuprate superconductors: 1) AF*, a fractionalized antiferromagnet where the spinons are paired into a state with long-ranged N\'{e}el order and the chargons are 1/2-filled and (Mott) insulating, 2) the nodal liquid, a fractionalized insulator where the spinons are d-wave paired and the chargons are uncondensed, and 3) the d-wave superconductor, where the chargons are condensed and the spinons retain a d-wave gap. Working within the $Z_2$ gauge theory of such fractionalized phases, our results should be valid at scales below the vison gap. However, on a phenomenological level, our results should apply to any spin-charge separated system where the excitations have these low-energy effective forms. Comparison with ARPES data in the undoped, pseudogapped, and superconducting regions is made.Comment: 10 page

Beam ion losses due to energetic particle geodesic acoustic modes

We report the first experimental observations of fast-ion loss in a tokamak due to energetic particle driven geodesic acoustic modes (EGAMs). A fast-ion loss detector installed on the DIII-D tokamak observes bursts of beam ion losses coherent with the EGAM frequency. The EGAM activity results in a significant loss of beam ions, comparable to the first orbit losses. The pitch angles and energies of the measured fast-ion losses agree with predictions from a full orbit simulation code SPIRAL, which includes scattering and slowing-down.U.S. Department of Energy DE-FC02-04ER 54698, SC-G903402, DE-AC02-09CH1146

Properties of Flares-Generated Seismic Waves on the Sun

The solar seismic waves excited by solar flares (``sunquakes'') are observed as circular expanding waves on the Sun's surface. The first sunquake was observed for a flare of July 9, 1996, from the Solar and Heliospheric Observatory (SOHO) space mission. However, when the new solar cycle started in 1997, the observations of solar flares from SOHO did not show the seismic waves, similar to the 1996 event, even for large X-class flares during the solar maximum in 2000-2002. The first evidence of the seismic flare signal in this solar cycle was obtained for the 2003 ``Halloween'' events, through acoustic ``egression power'' by Donea and Lindsey. After these several other strong sunquakes have been observed. Here, I present a detailed analysis of the basic properties of the helioseismic waves generated by three solar flares in 2003-2005. For two of these flares, X17 flare of October 28, 2003, and X1.2 flare of January 15, 2005, the helioseismology observations are compared with simultaneous observations of flare X-ray fluxes measured from the RHESSI satellite. These observations show a close association between the flare seismic waves and the hard X-ray source, indicating that high-energy electrons accelerated during the flare impulsive phase produced strong compression waves in the photosphere, causing the sunquake. The results also reveal new physical properties such as strong anisotropy of the seismic waves, the amplitude of which varies significantly with the direction of propagation. The waves travel through surrounding sunspot regions to large distances, up to 120 Mm, without significant decay. These observations open new perspectives for helioseismic diagnostics of flaring active regions on the Sun and for understanding the mechanisms of the energy release and transport in solar flares.Comment: 12 pages, 4 figures, submitted to Ap

New self-assembling multifunctional templates for the biofabrication and controlled self-release of cultured tissue

The need to source live human tissues for research and clinical applications has been a major driving force for the development of new biomaterials. Ideally, these should elicit the formation of scaffold-free tissues with native-like structure and composition. In this study, we describe a biologically interactive coating that combines the fabrication and subsequent self-release of live purposeful tissues using template–cell–environment feedback. This smart coating was formed from a self-assembling peptide amphiphile comprising a proteasecleavable sequence contiguous with a cell attachment and signaling motif. This multifunctional material was subsequently used not only to instruct human corneal or skin fibroblasts to adhere and deposit discreet multiple layers of native extracellular matrix but also to govern their own self-directed release from the template solely through the action of endogenous metalloproteases. Tissues recovered through this physiologically relevant process were carrier-free and structurally and phenotypically equivalent to their natural counterparts. This technology contributes to a new paradigm in regenerative medicine, whereby materials are able to actively direct and respond to cell behavior. The novel application of such materials as a coating capable of directing the formation and detachment of complex tissues solely under physiological conditions can have broad use for fundamental research and in future cell and tissue therapies

Quantum information processing in bosonic lattices

We consider a class of models of self-interacting bosons hopping on a lattice. We show that properly tailored space-temporal coherent control of the single-body coupling parameters allows for universal quantum computation in a given sector of the global Fock space. This general strategy for encoded universality in bosonic systems has in principle several candidates for physical implementation.Comment: 4 pages, 2 figs, RevTeX 4; updated to the published versio

Severe disruption and disorganization of dermal collagen fibrils in early striae gravidarum

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142909/1/bjd15895.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142909/2/bjd15895_am.pd

Existence of the Abrikosov vortex state in two-dimensional type-II superconductors without pinning

Theory alternative to the vortex lattice melting theories is advertised. The vortex lattice melting theories are science fiction cond-mat/9811051 because the Abrikosov state is not the vortex lattice with crystalline long-range order. Since the fluctuation correction to the Abrikosov solution is infinite in the thermodynamic limit (K.Maki and H.Takayama, 1972) any fluctuation theory of the mixed state should consider a superconductor with finite sizes. Such nonperturbative theory for the easiest case of two-dimensional superconductor in the lowest Landau level approximation is presented in this work. The thermodynamic averages of the spatial average order parameter and of the Abrikosov parameter $\beta_{a}$ are calculated. It is shown that the position H_{c4} of the transition into the Abrikosov state (i.e. in the mixed state with long-range phase coherence) depends strongly on sizes of two-dimensional superconductor. Fluctuations eliminate the Abrikosov vortex state in a wide region of the mixed state of thin films with real sizes and without pinning disorders, i.e. H_{c4} << H_{c2}. The latter has experimental corroboration in Phys.Rev.Lett. 75, 2586 (1995).Comment: 4 pages, 0 figure