Foreshock cavities and internal foreshock boundaries

We present two case studies of cluster encounters with foreshock cavities. For one event, we are able, for the first time, to accurately relate the observation of a foreshock cavity to the measured position of the bow shock. This allows us to compute the shock angle, a vital parameter in models of foreshock cavity formation, with greater confidence than any previous study. This cavity appears to be elongated along the magnetic field and we use the multispacecraft nature of the Cluster mission to constrain its field-parallel and -perpendicular extent. We show that this event is embedded within a region of field-aligned ion beams. This is the first time a foreshock cavity has been shown to be surrounded by foreshock ion beams. A second foreshock cavity is associated with a small rotation in the interplanetary magnetic field (IMF). We show that this event appears on the boundary between an interval when the spacecraft were inside the ion foreshock, and an excursion upstream. This is the first report of a foreshock cavity observed during the traversal of the global foreshock. This second event has some features expected from the new Sibeck et al. (2008) model of cavities as brief encounters with a spatial boundary in the global foreshock.     

Submillimeter/millimeter observations of the molecular clouds associated with Tycho's supernova remnant

We have carried out CO J = 2-1 and CO J = 3-2 observations toward Tycho's supernova remnant(SNR) using the KOSMA 3m-telescope.From these observations,we identified three molecular clouds(MCs) around the SNR.The small cloud in the southwest was discovered for the first time.In the north and east,two MCs(Cloud A and Cloud B) adjacent in space display a bow-shaped morphology,and have broad emission lines,which provide some direct evidences of the SNR-MCs interaction.The MCs are revealed at-69--59 km s-1,coinci...     

The orbital and superhump periods of the dwarf nova HS 0417+7445 in Camelopardalis

We present the 2005–2010 outburst history of the SU UMa-type dwarf HS 0417+7445, along with a detailed analysis of extensive time-series photometry obtained in March 2008 during the second recorded superoutburst of the system. The mean outburst interval is 197 ± 59 d, with a median of 193 d. The March 2008 superoutburst was preceded by a precursor outburst, had an amplitude of 4.2 magnitudes, and the whole event lasted about 16 days. No superhumps were detected during the decline from the precursor outburst, and our data suggests instead that orbital humps were present during that phase. Early superhumps detected during the rise to the superoutburst maximum exhibited an unusually large fractional period excess of ? = 0.137 (P_sh = 0.0856(88) d). Following the maximum, a linear decline in brightness followed, lasting at least 6 days. During this decline, a stable superhump period of P_sh = 0.07824(2) d was measured. Superimposed on the superhumps were orbital humps, which allowed us to accurately measure the orbital period of HS 0417+7445, P_orb = 0.07531(8) d, which was previously only poorly estimated. The fractional superhump period excess during the main phase of the outburst was ? = 0.037, which is typical for SU UMa dwarf novae with similar orbital period. Our observations are consistent with the predictions of the thermal-tidal instability model for the onset of superoutbursts, but a larger number of superoutbursts with extensive time-series photometry during the early phases of the outburst would be needed to reach a definite conclusion on the cause of superoutbursts.     

CTBT seismic monitoring using coherent and incoherent array processing

Journal of Seismology - The detection and location capability of the International Monitoring System for small seismic events in the continental and oceanic regions surrounding the Sea of Japan is...     

Seven possible states of geospatial data with respect to map projection and definition: a novel pedagogical device for GIS education

ABSTRACT

Conceptually, the theory and implementation of “map projection” in geographic information system (GIS) technology is difficult to comprehend for most introductory students and novice users. Compounding this difficulty is the concept of a “map projection file” that defines map projection parameters of geo-spatial data. The problem of the “missing projection file” appears ubiquitous for all users, especially in practice where data is widely shared. Another common problem is inadvertent misapplication of the “Define Projection” tool that can result in a GIS dataset with an incorrectly defined map projection file. GIS education should provide more guidance in differentiating the concepts of map projection versus projection files by increasing understanding and minimizing common errors. A novel pedagogical device is introduced in this paper: the seven possible states of GIS data with respect to map projection and definition. The seven possible states are: (1) a projected coordinate system (PCS) that is correctly defined, (2) a PCS that is incorrectly defined, (3) a PCS that is undefined, (4) a geographic coordinate system (GCS) that is correctly defined, (5) a GCS that is incorrectly defined, (6) a GCS that is undefined, and (7) a non-GCS. Recently created automated troubleshooting tools to determine a missing map projection file are discussed.     

Hydromagnetic waves in a thin rotating spherical shell

We consider an electrically conducting fluid confined to a thin rotating spherical shell in which the Elsasser and magnetic Reynolds numbers are assumed to be large while the Rossby number is assumed to vanish in an appropriate limit. This may be taken as a simple model for a possible stable layer at the top of the Earth's outer core. It may also be a model for the thin shells which are thought to be a source of the magnetic fields of some planets such as Mercury or Uranus. Linear hydromagnetic waves are studied using a multiple scale asymptotic scheme in which boundary layers and the associated boundary conditions determine the structure of the waves. These waves are assumed to be of the form of an asymptotic series expanded about an ambient magnetic field which vanishes on the equatorial plane and velocity and pressure fields which do not. They take the form of short wave, slowly varying wave trains. The results are compared to the author's previous work on such waves in cylindrical geometry in which the boundary conditions play no role. The approximation obtained is significantly different from that obtained in the previous work in that an essential singularity appears at the equator and nonequatorial wave regions appear.     

The Spatial Dialectics of Modernity and Retail Affect at Abasto Shopping,Buenos Aires,Argentina

Abstract

The paper is about the political life of a building: the Abasto. Located in what was called the “most porteño” neighborhood in the first part of the 20th century (“porteño” is someone from central Buenos Aires) when it functioned as the city's main food market, the Abasto became a massive shopping mall in 1998 amid rapid neoliberal restructuring. This paper charts the political life of this building in two steps. First, by drawing on theories of socio-spatial dialectics, this paper charts the history of the Abasto as an urban object in a wider political landscape of porteño modernity. Second, by incorporating recent theories of affect and presenting findings from field work carried out at the mall in 2010 and 2011, this paper develops a framework for understanding the politics of consumption in a “post-neoliberal” urban landscape.     

An Object Extraction Approach for Impervious Surface Classification with Very-High-Resolution Imagery

Detailed land cover maps provide important information for research and decision-making but are often expensive to develop and can become outdated quickly. Widespread availability of aerial photography provides increased accessibility of high-resolution imagery and the potential to produce high-accuracy land cover classifications. However, these classifications often require expert knowledge and are time consuming. Our goal was to develop an efficient, accurate technique for classifying impervious surface in urbanizing Wake County, North Carolina. Using an iterative training technique, we classified 111 nonmosaicked, very-high-resolution images using the Feature Analyst software developed by Visual Learning Systems. Feature Analyst provides object extraction classifications by analyzing spatial context in relation to spectral data to classify high-resolution imagery. Our image classification results were 95 percent accurate in impervious surface extraction, with an overall total accuracy of 92 percent. Using this method, users with relatively limited geographic information system (GIS) training and modest budgets can produce highly accurate object-extracted classifications of impervious and pervious surface that are easily manipulated in a GIS.