Thrombospondin-1-Mediated Metastasis Suppression by the Primary Tumor in Human Melanoma Xenografts

Some cancer patients show accelerated growth of pre-existing metastases after removal of the primary tumor. The purpose of this study was to investigate whether primary tumor-induced metastasis suppression can be mediated by thrombospondin-1 in melanoma. Human melanoma xenografts (D-12, R-18, and U-25) were used as models of melanoma in humans. Melanoma angiogenesis, lung colonization, and spontaneous pulmonary metastasis were inhibited in mice bearing D-12, U-25, or thrombospondin-1 overexpressing R-18 tumors, which showed high thrombospondin-1 expression and secreted large quantities of thrombospondin-1 into the blood, but not in mice bearing wild-type R-18 tumors, which were negative for thrombospondin-1. D-12 tumors suppressed the growth of their own spontaneous metastases. The anti-angiogenic and anti-metastatic effects of D-12 and U-25 tumors were blocked in mice treated with thrombospondin-1 neutralizing antibody. Dormant avascular microcolonies having an elevated apoptotic activity were seen in the lungs of mice bearing D-12 or U-25 tumors, whereas only neovascularized lung macrocolonies were seen in control and antibody-treated mice. This study suggests that some melanoma patients may benefit from combined local treatment and long-term anti-angiogenic therapy involving thrombospondin-1

Low frequency elastic wave propagation in 2D locally resonant phononic crystal with asymmetric resonator

The resonance modes and the related effects to the transmission of elastic waves in a two dimensional phononic crystal formed by periodic arrangements of a two blocks unit cell in one direction are studied. The unit cell consists of two asymmetric elliptic cylinders coated with silicon rubber and embedded in a rigid matrix. The modes are obtained by the semi-analytic method in the least square collocation scheme and confirmed by the finite element method simulations. Two resonance modes, corresponding to the vibration of the cylinder along the long and short axes, give rise to resonance reflections of elastic waves. One mode in between the two modes, related to the opposite vibration of the two cylinders in the unit cell in the direction along the layer, results in the total transmission of elastic waves due to zero effective mass density at the frequency. The resonance frequency of this new mode changes continuously with the orientation angle of the elliptic resonator.Comment: 17 pages, 7 figure

Laser cooling of a nanomechanical resonator mode to its quantum ground state

We show that it is possible to cool a nanomechanical resonator mode to its ground state. The proposed technique is based on resonant laser excitation of a phonon sideband of an embedded quantum dot. The strength of the sideband coupling is determined directly by the difference between the electron-phonon couplings of the initial and final states of the quantum dot optical transition. Possible applications of the technique we describe include generation of non-classical states of mechanical motion.Comment: 5 pages, 3 figures, revtex

Self-similar impulsive capillary waves on a ligament

We study the short-time dynamics of a liquid ligament, held between two solid cylinders, when one is impulsively accelerated along its axis. A set of one-dimensional equations in the slender-slope approximation is used to describe the dynamics, including surface tension and viscous effects. An exact self-similar solution to the linearized equations is successfully compared to experiments made with millimetric ligaments. Another non-linear self-similar solution of the full set of equations is found numerically. Both the linear and non-linear solutions show that the axial depth at which the liquid is affected by the motion of the cylinder scales like $\sqrt{t}$. The non-linear solution presents the peculiar feature that there exists a maximum driving velocity $U^\star$ above which the solution disappears, a phenomenon probably related to the de-pinning of the contact line observed in experiments for large pulling velocities

Wannier-Stark ladders in one-dimensional elastic systems

The optical analogues of Bloch oscillations and their associated Wannier-Stark ladders have been recently analyzed. In this paper we propose an elastic realization of these ladders, employing for this purpose the torsional vibrations of specially designed one-dimensional elastic systems. We have measured, for the first time, the ladder wave amplitudes, which are not directly accessible either in the quantum mechanical or optical cases. The wave amplitudes are spatially localized and coincide rather well with theoretically predicted amplitudes. The rods we analyze can be used to localize different frequencies in different parts of the elastic systems and viceversa.Comment: 10 pages, 6 figures, accepted in Phys. Rev. Let

Artemis Curation: Preparing for Sample Return from the Lunar South Pole

Space Policy Directive-1 mandates that the United States will lead the return of humans to the Moon for long-term exploration and utilization, followed by human missions to Mars and other destinations. In addition, the Vice President stated that It is the stated policy of this administration and the United States of America to return American astronauts to the Moon within the next five years, that is, by 2024. These efforts, under the umbrella of the recently formed Artemis Program, include such historic goals as the flight of the first woman to the Moon and the exploration of the lunar south-polar region. Among the top priorities of the Artemis Program is the return of a suite of geologic samples, providing new and significant opportunities for progressing lunar science and human exploration. In particular, successful sample return is necessary for understanding the history of volatiles in the Solar System and the evolution of the Earth-Moon system, fully constraining the hazards of the lunar polar environment for astronauts, and providing the necessary data for constraining the abundance and distribution of resources for in-situ resource utilization (ISRU). Here we summarize the ef-forts of the Astromaterials Acquisition and Curation Office (hereafter referred to as the Curation Office) to ensure the success of Artemis sample return (per NASA Policy Directive (NPD) 7100.10E)

Neuropathologic basis of frontotemporal dementia in progressive supranuclear palsy.

BackgroundProgressive supranuclear palsy (PSP) is a neurodegenerative disorder characterized by neuronal loss in the extrapyramidal system with pathologic accumulation of tau in neurons and glia. The most common clinical presentation of PSP, referred to as Richardson syndrome, is that of atypical parkinsonism with vertical gaze palsy, axial rigidity, and frequent falls. Although cognitive deficits in PSP are often ascribed to subcortical dysfunction, a subset of patients has dementia with behavioral features similar to the behavioral variant of frontotemporal dementia. In this study we aimed to identify the clinical and pathological characteristics of PSP presenting with frontotemporal dementia.MethodsIn this study, we compared clinical and pathologic characteristics of 31 patients with PSP with Richardson syndrome with 15 patients with PSP with frontotemporal dementia. For pathological analysis, we used semiquantitative methods to assess neuronal and glial lesions with tau immunohistochemistry, as well image analysis of tau burden using digital microscopic methods.ResultsWe found greater frontal and temporal neocortical neuronal tau pathology in PSP with frontotemporal dementia compared with PSP with Richardson syndrome. White matter tau pathology was also greater in PSP with frontotemporal dementia than PSP with Richardson syndrome. Genetic and demographic factors were not associated with atypical distribution of tau pathology in PSP with frontotemporal dementia.ConclusionsThe results confirm the subset of cognitive-predominant PSP mimicking frontotemporal dementia in PSP. PSP with frontotemporal dementia has distinct clinical features that differ from PSP with Richardson syndrome, as well as differences in distribution and density of tau pathology. © 2019 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society

Angular Radii of Stars via Microlensing

We outline a method by which the angular radii of giant and main sequence stars in the Galactic bulge can be measured to a few percent accuracy. The method combines ground-based photometry of caustic-crossing bulge microlensing events, with a handful of precise astrometric measurements of the lensed star during the event, to measure the angular radius of the source, theta_*. Dense photometric coverage of one caustic crossing yields the crossing timescale dt. Less frequent coverage of the entire event yields the Einstein timescale t_E and the angle phi of source trajectory with respect to the caustic. The photometric light curve solution predicts the motion of the source centroid up to an orientation on the sky and overall scale. A few precise astrometric measurements therefore yield theta_E, the angular Einstein ring radius. Then the angular radius of the source is obtained by theta_*=theta_E(dt/t_E) sin(phi). We argue that theta_* should be measurable to a few percent accuracy for Galactic bulge giant stars using ground-based photometry from a network of small (1m-class) telescopes, combined with astrometric observations with a precision of ~10 microarcsec to measure theta_E. We find that a factor of ~50 times fewer photons are required to measure theta_E to a given precision for binary-lens events than single-lens events. Adopting parameters appropriate to the Space Interferometry Mission (SIM), ~7 min of SIM time is required to measure theta_E to ~5% accuracy for giant sources in the bulge. For main-sequence sources, theta_E can be measured to ~15% accuracy in ~1.4 hours. With 10 hrs of SIM time, it should be possible to measure theta_* to ~5% for \~80 giant stars, or to 15% for ~7 main sequence stars. A byproduct of such a campaign is a significant sample of precise binary-lens mass measurements.Comment: 13 pages, 3 figures. Revised version, minor changes, required SIM integration times revised upward by ~60%. Accepted to ApJ, to appear in the March 20, 2003 issue (v586

Mode resolved travel time statistics for elastic rays in three-dimensional billiards

We consider the ray limit of propagating ultrasound waves in three-dimensional bodies made from an homogeneous, isotropic, elastic material. Using a Monte Carlo approach, we simulate the propagation and proliferation of elastic rays using realistic angle dependent reflection coefficients, taking into account mode conversion and ray-splitting. For a few simple geometries, we analyse the long time equilibrium distribution focussing on the energy ratio between compressional and shear waves. Finally, we study the travel time statistics, i.e. the distribution of the amount of time a given trajectory spends as a compressional wave, as compared to the total travel time. These results are intimately related to recent elastodynamics experiments on Coda wave interferometry by Lobkis and Weaver [Phys. Rev. E 78, 066212 (2008)].Comment: 11 pages, 10 figures, (minor corrections, improved style

A multi-zone model for simulating the high energy variability of TeV blazars

We present a time-dependent multi-zone code for simulating the variability of Synchrotron-Self Compton (SSC) sources. The code adopts a multi-zone pipe geometry for the emission region, appropriate for simulating emission from a standing or propagating shock in a collimated jet. Variations in the injection of relativistic electrons in the inlet propagate along the length of the pipe cooling radiatively. Our code for the first time takes into account the non-local, time-retarded nature of synchrotron self-Compton (SSC) losses that are thought to be dominant in TeV blazars. The observed synchrotron and SSC emission is followed self-consistently taking into account light travel time delays. At any given time, the emitting portion of the pipe depends on the frequency and the nature of the variation followed. Our simulation employs only one additional physical parameter relative to one-zone models, that of the pipe length and is computationally very efficient, using simplified expressions for the SSC processes. The code will be useful for observers modeling GLAST, TeV, and X-ray observations of SSC blazars.Comment: ApJ, accepte