726 research outputs found
International Capital Flows and the Frankel-Dooley-Mathieson Puzzle
No full textFrankel et al (1986) pointed out that industrialized countries have larger saving rate coefficients than do developing countries in the framework of Feldstein-Horioka puzzle. This is referred to as the Frankel-Dooley-Mathieson puzzle in this paper. This paper extends past analyses by incorporating indices of a domestic institutional and policy environment. Applying the resulting model to Sub-Saharan African countries, saving rate coefficients larger than those previously imagined were obtained. These results are consistent with the reality of capital regulations and other factors resulting in low capital flows in developing countries.capital mobility
Separating sets of strings by finding matching patterns is almost always hard
No full textWe study the complexity of the problem of searching for a set of patterns that separate two given sets of strings. This problem has applications in a wide variety of areas, most notably in data mining, computational biology, and in understanding the complexity of genetic algorithms. We show that the basic problem of finding a small set of patterns that match one set of strings but do not match any string in a second set is difficult (NP-complete, W[2]-hard when parameterized by the size of the pattern set, and APX-hard). We then perform a detailed parameterized analysis of the problem, separating tractable and intractable variants. In particular we show that parameterizing by the size of pattern set and the number of strings, and the size of the alphabet and the number of strings give FPT results, amongst others. © 2017 Elsevier B.V
REGULATORY ROLE OF OX22HIGH T-CELLS IN MERCURY-INDUCED AUTOIMMUNITY IN THE BROWN NORWAY RAT
No full textThe monoclonal antibody OX22 defines a functional split within CD4+ T cells in the rat, with OX22high cells mainly producing interleukin 2 (IL-2) and interferon γ and responsible for delayed-type hypersensitivity responses, and OX22low cells mainly producing IL-4 and -5 and responsible for providing B cell help. There are reciprocal interactions between OX22high and OX22low cells, and it has been suggested that the OX22low subset has a role in the prevention of autoimmunity. We have used OX22 in vivo to define the role of these subsets in mercuric chloride-induced autoimmunity in the Brown Norway rat. In this model, there is polyclonal B cell activation and animals develop widespread tissue injury. Treatment of thymectomized animals with OX22 led to a profound reduction in the number of OX22high T cells in the peripheral blood. OX22-treated animals consistently developed more severe tissue injury than controls given an irrelevant antibody of the same isotype. Control animals pretreated with broad spectrum antimicrobial drugs showed milder tissue injury, but this protective effect of antimicrobials was lost in OX22-treated animals. Transfer of naive T cells to OX22-treated animals provided protection, but if T cells were depleted in vitro of OX22high cells before transfer, this effect was lost. These data provide evidence for a protective immunoregulatory role for OX22high T cells in mercuric chloride-induced autoimmunity.link_to_subscribed_fulltex
Investigation of a resistive anode detector for astronomical spectroscopy
No full textA large format two dimensional photon counting detector has
been evaluated as a detector for astronomical spectroscopy. The
design comprises an 320 photocathode, a tandem MCP gain stage and a
circular arc terminated resisitive anode to provide pOSitional
coordinates of detected events. The system is run from an LSI 11/23
computer operating under FORTH control.
The micro-channel plate operating characteristics and the
detector's resolution, quantum efficiency and imaging performance
have been studied. The principal areas requiring design improvement
are found to be the micro-channel plate gain,
processing and photocathode quality.
electronic signal
The detector has been employed in a observing program on a
0.5 m telescope. Spectra of IAU faint radial velocity standards and
the eclipsing binary system s-l Cam have been obtained and analysed
to assess the system's performance
The parameterized complexity of editing graphs for bounded degeneracy
No full textAbstractWe examine the parameterized complexity of the problem of editing a graph to obtain an r-degenerate graph. We show that for the editing operations vertex deletion and edge deletion, both separately and combined, the problem is W[P]-complete, and remains W[P]-complete even if the input graph is already (r+1)-degenerate, or has maximum degree 2r+1 for all r≥2.We also demonstrate fixed-parameter tractability for several Clique based problems when the input graph has bounded degeneracy
Predation events by transient killer whales on marine mammals in Monterey Bay, California.
No full textPrey include, (A) California sea lion being pursued, (B) juvenile northern elephant seal being hit by the tail of a transient, (C) Pacific white-sided dolphin being thrown through the air, (D) Adult male transient killer whale OCT004 grasping the rostrum of a minke whale. Photo credits: Chelsea Mathieson (A), Peggy West-Stap (B-D).</p
Using Network Alignment to Identify Conserved Consumer Behaviour Modelling Constructs
No full textExtracting topological information from networks is a central problem in many fields including business analytics. With the increase in large-scale datasets, effectively comparing similarities and differences between networks is impossible without automation. In some cases, computational search of simple subgraphs is used to understand the structure of a network. These approaches, however, miss the “global picture” of network similarity. Here we examine the Network Alignment problem, in which we look for a mapping between vertex sets of two networks preserving topological information. Elsewhere, we showed that data analytics problems are often of varied computational complexity. We prove that this problem is W[1]-complete for several parameterizations. Since we expect large instances in the data analytics field, our result indicates that this problem is a prime candidate for metaheuristic approaches as it will be hard in practice to solve exact methods. We develop a memetic algorithm and demonstrate the effectiveness of the Network Alignment problem as a tool for discovering structural information through an application in the area of consumer behaviour modelling. We believe this to be the first demonstration of such an approach in the social sciences and in particular a consumer analytics application
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