AT-GIS: highly parallel spatial query processing with associative transducers

Users in many domains, including urban planning, transportation, and environmental science want to execute analytical queries over continuously updated spatial datasets. Current solutions for largescale spatial query processing either rely on extensions to RDBMS, which entails expensive loading and indexing phases when the data changes, or distributed map/reduce frameworks, running on resource-hungry compute clusters. Both solutions struggle with the sequential bottleneck of parsing complex, hierarchical spatial data formats, which frequently dominates query execution time. Our goal is to fully exploit the parallelism offered by modern multicore CPUs for parsing and query execution, thus providing the performance of a cluster with the resources of a single machine. We describe AT-GIS, a highly-parallel spatial query processing system that scales linearly to a large number of CPU cores. ATGIS integrates the parsing and querying of spatial data using a new computational abstraction called associative transducers(ATs). ATs can form a single data-parallel pipeline for computation without requiring the spatial input data to be split into logically independent blocks. Using ATs, AT-GIS can execute, in parallel, spatial query operators on the raw input data in multiple formats, without any pre-processing. On a single 64-core machine, AT-GIS provides 3× the performance of an 8-node Hadoop cluster with 192 cores for containment queries, and 10× for aggregation queries

WHO BENEFITS FROM FUNDS OF HEDGE FUNDS? A CRITIQUE OF ALTERNATIVE ORGANIZATIONAL STRUCTURES IN THE HEDGE FUND INDUSTRY (I)

This paper provides a critique of alternative organizational structures in the hedge fund industry. Our critique is facilitated by several stylized models describing alternative industry structures. The models include: (1) An insideonly hedge fund model; (2) A straddling hedge fund model; (3) A straddling “feeder” fund of funds (FOF) hedge fund model; (4) A stand-alone outside hedge fund; and (5) An outside “feeder” FOF hedge fund model. Our discussion of these models, which centers on benefits vs. fundamental problems related to illiquidity, information asymmetry, and conflicts of interest, leads to several hypotheses about the differential characteristics and return performance of both individual hedge funds and FOFs.Hedge funds, Funds of funds, Illiquidity, Information asymmetry, Conflicts of interest, Adjacency risk, Contagion, Return performance

Southern Arizona riparian habitat: Spatial distribution and analysis

The objectives of this study were centered around the demonstration of remote sensing as an inventory tool and researching the multiple uses of riparian vegetation. Specific study objectives were to: (1) map riparian vegetation along the Gila River, San Simon Creek, San Pedro River, Pantano Wash, (2) determine the feasibility of automated mapping using LANDSAT-1 computer compatible tapes, (3) locate and summarize existing mpas delineating riparian vegetation, (4) summarize data relevant to Southern Arizona's riparian products and uses, (5) document recent riparian vegetation changes along a selected portion of the San Pedro River, (6) summarize historical changes in composition and distribution of riparian vegetation, and (7) summarize sources of available photography pertinent to Southern Arizona

Use of Earth Resources Technological Satellite (ERTS) data in a natural resource inventory

There are no author-identified significant results in this report

"My Life as it is has Value:" A Narrative Approach to Understanding Life Course Experiences of Older Adults with Schizophrenia

This study used thematic narrative analysis to address the question: How do older adults who experience serious ongoing symptoms of schizophrenia understand and express stories of their personal survivorship in the face of life-course and present-time adversities? Framed by the developmental life course perspective and using major constructs of the theory of cumulative adversity and advantage to formulate a line of semi-structured questioning for narrative interviews about the life course experiences of older adults with schizophrenia who experienced ongoing illness symptoms, analysis of 31 interviews with six older adults with schizophrenia yielded findings across five central areas. Shared core themes included: 1) "My life as it is has value:" Narrating schizophrenia in later life; 2) "I have a key and live like a real person:" Homelessness and housing challenges in retrospect; 3) "There's not been jobs:" The meaning of employment; 4) "God told me how we're going to meet back up:" Narratives of relational conflict and loss, adjustment and renewal. A fifth area of findings developed the theory of cumulative adversity and advantage across the life course with schizophrenia. These results improve our understanding of the subjective experience of a highly vulnerable but grossly understudied and underserved population. Recommendations for focusing future research and development of more effective social work practice and policies are made

A new array for the study of ultra high energy gamma-ray sources

The design and operation of a 32 x 1 10 to the 15th power sq m array of scintillation detectors for the detection of 10 to the 15th power eV cosmic rays is described with an expected angular resolution of 1 deg, thus improving the present signal/background ratio for gamma ray sources. Data are recorded on a hybrid CAMAC, an in-house system which uses a laser and Pockel-Cell arrangement to routinely calibrate the timing stability of the detectors

Elastic cavitation, tube hollowing, and differential growth in plants and biological tissues

Elastic cavitation is a well-known physical process by which elastic materials under stress can open cavities. Usually, cavitation is induced by applied loads on the elastic body. However, growing materials may generate stresses in the absence of applied loads and could induce cavity opening. Here, we demonstrate the possibility of spontaneous growth-induced cavitation in elastic materials and consider the implications of this phenomenon to biological tissues and in particular to the problem of schizogenous aerenchyma formation

On Love-type waves in a finitely deformed magnetoelastic layered half-space

In this paper, the propagation of Love-type waves in a homogeneously and finitely deformed layered half-space of an incompressible non-conducting magnetoelastic material in the presence of an initial uniform magnetic field is analyzed. The equations and boundary conditions governing linearized incremental motions superimposed on an underlying deformation and magnetic field for a magnetoelastic material are summarized and then specialized to a form appropriate for the study of Love-type waves in a layered half-space. The wave propagation problem is then analyzed for different directions of the initial magnetic field for two different magnetoelastic energy functions, which are generalizations of the standard neo-Hookean and Mooney–Rivlin elasticity models. The resulting wave speed characteristics in general depend significantly on the initial magnetic field as well as on the initial finite deformation, and the results are illustrated graphically for different combinations of these parameters. In the absence of a layer, shear horizontal surface waves do not exist in a purely elastic material, but the presence of a magnetic field normal to the sagittal plane makes such waves possible, these being analogous to Bleustein–Gulyaev waves in piezoelectric materials. Such waves are discussed briefly at the end of the paper

The Computational Complexity of Symbolic Dynamics at the Onset of Chaos

In a variety of studies of dynamical systems, the edge of order and chaos has been singled out as a region of complexity. It was suggested by Wolfram, on the basis of qualitative behaviour of cellular automata, that the computational basis for modelling this region is the Universal Turing Machine. In this paper, following a suggestion of Crutchfield, we try to show that the Turing machine model may often be too powerful as a computational model to describe the boundary of order and chaos. In particular we study the region of the first accumulation of period doubling in unimodal and bimodal maps of the interval, from the point of view of language theory. We show that in relation to the ``extended'' Chomsky hierarchy, the relevant computational model in the unimodal case is the nested stack automaton or the related indexed languages, while the bimodal case is modeled by the linear bounded automaton or the related context-sensitive languages.Comment: 1 reference corrected, 1 reference added, minor changes in body of manuscrip