Individual and Collective Behavior of Small Vibrating Motors Interacting Through a Resonant Plate

We report on experiments of many small motors -- cell phone vibrators -- glued to and interacting through a resonant plate. We find that individual motors interacting with the plate demonstrate hysteresis in their steady-state frequency due to interactions with plate resonances. For multiple motors running simultaneously, the degree of synchronization between motors increases when the motors' frequencies are near a resonance of the plate, and the frequency at which the motors synchronize shows a history dependence.Comment: 7 pages, 8 figure

Dynamics of Large Fragments in the Tail of Active Asteroid P/2010 A2

We examine the motions of large fragments at the head of the dust tail of active asteroid P/2010 A2. In previous work we showed that these fragments were ejected from the primary nucleus in early 2009, either following a hypervelocity impact or by rotationally induced break-up. Here, we follow their positions through a series of Hubble Space Telescope images taken during the first half of 2010. The orbital evolution of each fragment allows us to constrain its velocity relative to the main nucleus after leaving its sphere of gravitational influence. We find that the fragments constituting a prominent X-shaped tail feature were emitted in a direction opposite to the motion of the asteroid and towards the south of its orbital plane. Derived emission velocities of these primary fragments range between 0.02 and 0.3 m/s, comparable to the ~0.08 m/s gravitational escape speed from the nucleus. Their sizes are on the order of decimeters or larger. We obtain the best fits to our data with ejection velocity vectors lying in a plane that includes the nucleus. This may suggest that the cause of the disruption of P/2010 A2 is rotational break-up.Comment: 30 pages, 8 figures, accepted for publication by The Astrophysical Journa

Periodic 2-graphs arising from subshifts

Higher-rank graphs were introduced by Kumjian and Pask to provide models for higher-rank Cuntz-Krieger algebras. In a previous paper, we constructed 2-graphs whose path spaces are rank-two subshifts of finite type, and showed that this construction yields aperiodic 2-graphs whose $C^*$-algebras are simple and are not ordinary graph algebras. Here we show that the construction also gives a family of periodic 2-graphs which we call \emph{domino graphs}. We investigate the combinatorial structure of domino graphs, finding interesting points of contact with the existing combinatorial literature, and prove a structure theorem for the $C^*$-algebras of domino graphs.Comment: 17 page

A comparison of refined models for flexible subassemblies

Interactions between structure response and control of large flexible space systems have challenged current modeling techniques and have prompted development of new techniques for model improvement. Due to the geometric complexity of envisioned large flexible space structures, finite element models (FEM's) will be used to predict the dynamic characteristics of structural components. It is widely accepted that these models must be experimentally 'validated' before their acceptance as the basis for final design analysis. However, predictions of modal properties (natural frequencies, mode shapes, and damping ratios) are often in error when compared to those obtained from Experimental Modal Analysis (EMA). Recent research efforts have resulted in the development of algorithmic approaches for model improvement, also referred to as system or structure identification

Perspective: Melanoma diagnosis and monitoring: Sunrise for melanoma therapy but early detection remains in the shade

Last revised 25 Jul 2016.Melanoma is one of the most dangerous forms of cancer. The five-year survival rate is 98% if it is detected early. However, this rate plummets to 63% for regional disease and 17% when tumors have metastasized, that is, spread to distant sites. Furthermore, the incidence of melanoma has been rising by about 3% per year, whereas the incidence of cancers that are more common is decreasing. A handful of targeted therapies have recently become available that have finally shown real promise for treatment, but for reasons that remain unclear only a fraction of patients respond long term. These drugs often increase survival by only a few months in metastatic patient groups before relapse occurs. More effective treatment may be possible if a diagnosis can be made when the tumor burden is still low. Here, an overview of the current state-of-the-art is provided along with an argument for newer technologies towards early point-of-care diagnosis of melanoma

Johne's disease or paratuberculosis (1993)

Johne's disease (pronounced "Yone-es") or paratuberculosis is an incurable wasting disease of adult cattle that is being increasingly recognized in the United States. Since prevalence rates in U.S.-slaughtered cows range from 2 to 18 percent, Johne's disease is now considered a major problem. It is of more concern in dairy herds than beef operations since there is a larger percentage of cases in the dairy cattle population than in beef.Reviewed October 1993 -- Extension website

Golan v. Holder: Copyright in the Image of the First Amendment

Does copyright violate the First Amendment? Professor Melville Nimmer asked this question forty years ago, and then answered it by concluding that copyright itself is affirmatively speech protective. Despite ample reason to doubt Nimmer’s response, the Supreme Court has avoided an independent, thoughtful, plenary review of the question. Copyright has come to enjoy an all-but-categorical immunity to First Amendment constraints. Now, however, the Court faces a new challenge to its back-of-the-hand treatment of this vital conflict. In Golan v. Holder the Tenth Circuit considered legislation (enacted pursuant to the Berne Convention and TRIPS) “restoring” copyright protection to millions of foreign works previously thought to belong to the public domain. The Tenth Circuit upheld the legislation, but not without noting that it appeared to raise important First Amendment concerns. The Supreme Court granted certiorari. This article addresses the issues in the Golan case, literally on the eve of oral argument before the Court. This article first considers the Copyright and Treaty Clauses, and then addresses the relationship between copyright and the First Amendment. The discussion endorses an understanding of that relationship in which the Amendment is newly seen as paramount, and copyright is newly seen in the image of the Amendment