A Comparison of AVIRIS and Landsat for Land Use Classification at the Urban Fringe

In this study we tested whether AVIRIS data allowed for improved land use classification over synthetic Landsat ETM+ data for a location on the urban-rural fringe of Colorado. After processing the AVIRIS image and creating a synthetic Landsat image, we used standard classification and post-classification procedures to compare the data sources for land use mapping. We found that, for this location, AVIRIS holds modest, but real, advantages over Landsat for the classification of heterogeneous and vegetated land uses. Furthermore, this advantage comes almost entirely from the large number of sensor spectral bands rather than the high Signal-to-Noise Ratio (SNR)

Preserving the Appointments Safety Valve

In 2007, Senate Majority Leader Harry Reid had a bright idea. While nominally in recess over Thanksgiving, Reid enlisted senators to return to the empty Senate chamber every few days to conduct pro forma sessions. These sessions, typically no longer than thirty seconds each, successfully prevented then-President George W. Bush from making a recess appointment of a controversial new Surgeon General. Following this success, Democrats deployed this device throughout the remainder of President Bush\u27s term in office. Bush, who had made forty recess appointments in 2006 alone, had been on pace to surpass President Ronald Reagan\u27s all-time record of 243. But because of the Reid maneuver, Bush made none at all in his final twenty-one months in office. In late 2010, the Senate Republicans returned the favor: They forced the Democrat- controlled Senate to revive the Reid maneuver to block a batch of President Barack Obama\u27s nominees during the break before the midterm elections. Again the maneuver successfully impeded the President from making any recess appointments. Republicans have since used the maneuver many times against Obama

Legal Guardrails for a Unicorn Crackdown

The Securities and Exchange Commission (SEC) is undertaking a historic effort to redraw the boundary between public and private companies. After years of watching—and sometimes encouraging—the explosive growth in less tightly regulated private markets and the proliferation of so-called “unicorns,” the agency is now reasserting its authority. A key arrow in the agency’s regulatory quiver is its authority under section 12(g) of the Securities Exchange Act of 1934 (Exchange Act) to force private companies to “go public” when they reach a certain size. The provision requires any company whose shares are “held of record” by more than 2,000 persons to take on the obligations imposed by federal securities regulations on public companies, including extensive disclosure. But today, this 2,000 shareholder trigger has no real constraining effect; because a single holder “of record” can easily (and often does) stand in for tens, hundreds, or even thousands of real beneficial owners, private companies can easily raise endless amounts of capital without tripping the threshold. Now, the SEC wants to close this loophole by mandating a “look-through” to the beneficial owners of the securities for purposes of the shareholder count. The details remain to be seen, but the agency is apparently eager to significantly curtail the ability of private companies to grow outside of the regulatory scrutiny that accompanies public company status. This paper proceeds in five Parts. Part I provides a brief background on the rise of private markets and the SEC’s budding efforts to reassert its authority in this domain. Part II examines the text and legislative history of section 12(g) and shows how Congress limited the agency’s authority to mandate a look-through for purposes of the shareholder count. Part III considers various possible interpretations of the SEC’s authority to mandate a look-through and shows that the more limited interpretations of this authority are the most reasonable. Part IV shows that the limited interpretations presented in Part III are also consistent with the small number of look-throughs previously authorized by the agency. Part V shows how these limited interpretations might significantly restrict the agency’s ability to fundamentally redraw the lines between public and private companies

Cycling chaos: its creation, persistence and loss of stability in a model of nonlinear magnetoconvection

We examine a model system where attractors may consist of a heteroclinic cycle between chaotic sets; this ‘cycling chaos’ manifests itself as trajectories that spend increasingly long periods lingering near chaotic invariant sets interspersed with short transitions between neighbourhoods of these sets. Such behaviour is robust to perturbations that preserve the symmetry of the system; we examine bifurcations of this state. We discuss a scenario where an attracting cycling chaotic state is created at a blowout bifurcation of a chaotic attractor in an invariant subspace. This differs from the standard scenario for the blowout bifurcation in that in our case, the blowout is neither subcritical nor supercritical. The robust cycling chaotic state can be followed to a point where it loses stability at a resonance bifurcation and creates a series of large period attractors. The model we consider is a ninth-order truncated ordinary differential equation (ODE) model of three-dimensional incompressible convection in a plane layer of conducting fluid subjected to a vertical magnetic field and a vertical temperature gradient. Symmetries of the model lead to the existence of invariant subspaces for the dynamics; in particular there are invariant subspaces that correspond to regimes of two-dimensional flows, with variation in the vertical but only one of the two horizontal directions. Stable two-dimensional chaotic flow can go unstable to three-dimensional flow via the cross-roll instability. We show how the bifurcations mentioned above can be located by examination of various transverse Liapunov exponents. We also consider a reduction of the ODE to a map and demonstrate that the same behaviour can be found in the corresponding map. This allows us to describe and predict a number of observed transitions in these models. The dynamics we describe is new but nonetheless robust, and so should occur in other applications

Pleiotropy of FRIGIDA enhances the potential for multivariate adaptation.

An evolutionary response to selection requires genetic variation; however, even if it exists, then the genetic details of the variation can constrain adaptation. In the simplest case, unlinked loci and uncorrelated phenotypes respond directly to multivariate selection and permit unrestricted paths to adaptive peaks. By contrast, 'antagonistic' pleiotropic loci may constrain adaptation by affecting variation of many traits and limiting the direction of trait correlations to vectors that are not favoured by selection. However, certain pleiotropic configurations may improve the conditions for adaptive evolution. Here, we present evidence that the Arabidopsis thaliana gene FRI (FRIGIDA) exhibits 'adaptive' pleiotropy, producing trait correlations along an axis that results in two adaptive strategies. Derived, low expression FRI alleles confer a 'drought escape' strategy owing to fast growth, low water use efficiency and early flowering. By contrast, a dehydration avoidance strategy is conferred by the ancestral phenotype of late flowering, slow growth and efficient water use during photosynthesis. The dehydration avoidant phenotype was recovered when genotypes with null FRI alleles were transformed with functional alleles. Our findings indicate that the well-documented effects of FRI on phenology result from differences in physiology, not only a simple developmental switch

Sparkling extreme-ultraviolet bright dots observed with Hi-C

Observing the Sun at high time and spatial scales is a step toward understanding the finest and fundamental scales of heating events in the solar corona. The high-resolution coronal (Hi-C) instrument has provided the highest spatial and temporal resolution images of the solar corona in the EUV wavelength range to date. Hi-C observed an active region on 2012 July 11 that exhibits several interesting features in the EUV line at 193 Å. One of them is the existence of short, small brightenings "sparkling" at the edge of the active region; we call these EUV bright dots (EBDs). Individual EBDs have a characteristic duration of 25 s with a characteristic length of 680 km. These brightenings are not fully resolved by the SDO/AIA instrument at the same wavelength; however, they can be identified with respect to the Hi-C location of the EBDs. In addition, EBDs are seen in other chromospheric/coronal channels of SDO/AIA, which suggests a temperature between 0.5 and 1.5 MK. Based on their frequency in the Hi-C time series, we define four different categories of EBDs: single peak, double peak, long duration, and bursty. Based on a potential field extrapolation from an SDO/HMI magnetogram, the EBDs appear at the footpoints of large-scale, trans-equatorial coronal loops. The Hi-C observations provide the first evidence of small-scale EUV heating events at the base of these coronal loops, which have a free magnetic energy of the order of 1026 erg. © 2014. The American Astronomical Society. All rights reserved