1,529 research outputs found
Joint asymptotic distributions of smallest and largest insurance claims
Assume that claims in a portfolio of insurance contracts are described by independent and identically distributed random variables with regularly varying tails and occur according to a near mixed Poisson process. We provide a collection of results pertaining to the joint asymptotic Laplace transforms of the normalised sums of the smallest and largest claims, when the length of the considered time interval tends to infinity. The results crucially depend on the value of the tail index of the claim distribution, as well as on the number of largest claims under consideration
Hazard assessment at Mount Etna using a hybrid lava flow inundation model and satellite-based land classification
International audienceUsing a lava flow emplacement model and a satellite-based land cover classification, we produce a map to allow assessment of the type and quantity of natural, agricultural and urban land cover at risk from lava flow invasion. The first step is to produce lava effusion rate contours, i.e., lines linking distances down a volcano’s flank that a lava flow will likely extend if fed at a given effusion rate from a predetermined vent zone. This involves first identifying a vent mask and then running a downhill flow path model from the edge of every pixel around the vent mask perimeter to the edge of the DEM. To do this, we run a stochastic model whereby the flow path is projected 1,000 times from every pixel around the vent mask perimeter with random noise being added to the DEM with each run so that a slightly different flow path is generated with each run. The FLOWGO lava flow model is then run down each path, at a series of effusion rates, to determine likely run-out distance for channel-fed flow extending down each path. These results are used to plot effusion rate contours. Finally, effusion rate contours are projected onto a land classification map (produced from an ASTER image of Etna) to assess the type and amount of each land cover class falling within each contour. The resulting maps are designed to provide a quick look-up capability to assess the type of land at risk from lava extending from any location at a range of likely effusion rates. For our first (2,000 m) vent zone case used for Etna, we find a total of area of ~680 km2 is at risk from flows fed at 40 m3 s−1, of which ~6 km2 is urban, ~150 km2 is agriculture and ~270 km2 is grass/woodland. The model can also be run for specific cases, where we find that Etna’s 1669 vent location, if active today, would likely inundate almost 11 km2 of urban land, as well as 15.6 km2 of agricultural land, including 9.5 km2 of olive groves and 5.2 km2 of vineyards and fruit/nut orchards
Ownership, competition, and financial disclosure
Empirical research on firms’ (dis)incentives to disclose investigates the effects of a range of variables including information asymmetry, agency costs, political costs, and proprietary costs. Verrecchia (2001) argues that economic-based models of disclosure must establish a link between financial reporting and its economic consequences. In response to Verrecchia (2001) and drawing on the industrial organization and strategic management disciplines we introduce a new variable (measuring insider ownership and industry competition) which links both the internal and external environments of the firm and demonstrate that it adds to our understanding of discretionary financial disclosure decisions. We test the model by examining voluntary segment disclosures in Australian firms. We find that our new variable linking the internal and external environment of the firm, alongside previously tested variables including ownership diffusion, return and size is significant. We conduct a series of robustness tests on our model and find that the significance of the model is robust to the inclusion of variables measuring the change in standard, acquisitions and disposals and cross listing on the US stock exchange
80-Gb/s OTDM system analysis of a vertical microcavity-based saturable absorber for the enhancement of pulse pedestal suppression
In future high-speed optical time-division-multiplexed (OTDM) systems, an important factor that needs to be considered for optical pulse generation schemes is the impact of pulse pedestals on the overall system performance. The results presented in this letter are two-fold; first, the impact due to the height of pulse pedestals in an 80-Gb/s OTDM system are established. Second, a solution is provided to overcome these high pedestal levels through the use of a vertical microcavity saturable absorber, which can significantly reduce the pulse pedestal level and give enhanced system performanc
Palatini Variational Principle for an Extended Einstein-Hilbert Action
We consider a Palatini variation on a generalized Einstein-Hilbert action. We
find that the Hilbert constraint, that the connection equals the Christoffel
symbol, arises only as a special case of this general action, while for
particular values of the coefficients of this generalized action, the
connection is completely unconstrained. We discuss the relationship between
this situation and that usually encountered in the Palatini formulation.Comment: 14 pages, LaTe
Absence of singular superconducting fluctuation corrections to thermal conductivity
We evaluate the superconducting fluctuation corrections to thermal
conductivity in the normal state which diverge as T approaches T_c. We find
zero total contribution for one, two and three-dimensional superconductors for
arbitrary impurity concentration. The method used is diagrammatic many-body
theory, and all contributions -- Aslamazov-Larkin (AL), Maki-Thompson (MT), and
density-of-states (DOS) -- are considered. The AL contribution is convergent,
whilst the divergences of the DOS and MT diagrams exactly cancel.Comment: 4 pages text; 2 figure
Status of Uncooled Infrared Detector Technology at ULIS, France
The high level of accumulated expertise by ULIS and CEA/LETI on uncooled microbolometers made from amorphous silicon enables ULIS to develop uncooled IRFPA with 17 µm pixel-pitch to enable the development of small power, small weight and power (SWaP) and high performance IR systems. Key characteristics of amorphous silicon based uncooled IR detector is described to highlight the advantage of this technology for system operation. A full range of products from 160 x 120 to 1024 x 768 has been developed and we will focus the paper on the ¼ VGA with 17 µm pixel pitch. Readout integrated circuit (ROIC) architecture is described highlighting innovations that are widely on-chip implemented to enable an easier operation by the user. The detector configuration (integration time, windowing, gain, scanning direction), is driven by a standard I²C link. Like most of the visible arrays, the detector adopts the HSYNC/VSYNC free-run mode of operation driven with only one master clock (MC) supplied to the ROIC which feeds back pixel, line and frame synchronisation. On-chip PROM memory for customer operational condition storage is available for detector characteristics. Low power consumption has been taken into account and less than 60 mW is possible in analogue mode at 60 Hz. A wide electrical dynamic range (2.4V) is maintained despite the use of advanced CMOS node. The specific appeal of this unit lies in the high uniformity and easy operation it provides. The reduction of the pixel-pitch turns this TEC-less ¼ VGA array into a product well adapted for high resolution and compact systems. Noise equivalent temperature difference (NETD) of 35 mK and thermal time constant of 10 ms have been measured leading to 350 mK.ms figure of merit. We insist on NETD trade-off with wide thermal dynamic range, as well as the high characteristics uniformity and pixel operability, achieved thanks to the mastering of the amorphous silicon technology coupled with the ROIC design. This technology node associated with advanced packaging technique, paves the way to compact low power system.Defence Science Journal, 2013, 63(6), pp.545-549, DOI:http://dx.doi.org/10.14429/dsj.63.5753
Ethnic Concerns and Latino Party Identification [post-print]
The accelerated growth of the Latino population in the United States has made Latinos a coveted addition to each major political party\u27s base. In this paper we examine the influence of ethnic concerns on the party identification of Latinos in the U.S. In contrast to previous studies, we account for Latinos’ perceptions of the political parties’ concern for their ethnic interests, allowing such interests to be self-defined. In a multinomial logit analysis of pooled data from three surveys of Latinos taken in 1999, 2004, and 2006, we find such perceptions do affect Latino partisanship, along with variables such as nativity and country of origin or ancestry. We also find a tendency toward independence among Latinos. Finally, we find movement toward the Democratic Party in 2004, once ethnic concerns are taken into account. One implication of the findings is that the party that can best persuade Latinos of their concern for their interests is the party most likely to gain their loyalties; indeed, the parties must earn those loyalties
Effect of the thermal gradient variation through geological time on basin modeling; a case study: The Paris basin.
Many studies investigated the thermal modeling of the Paris basin for petroleum interests during the 1970s. Most of the softwares developed by oil companies or research centers were based on the assumption of a constant thermal gradient. In order to take into consideration the variation of the thermal gradient during basin evolution, we developed the TherMO's Visual Basic 1D program. We applied our model to twenty boreholes located along a cross-section roughly running EW over 150 km in the center of the Paris basin. The numerical results were calibrated with organic matter maturity data. TherMO's simulates the amount of heat provided to the sedimentary organic matter. The heat parameter simulated shows lateral variation along the cross-section. It decreases from Rambouillet to Trou Aux Loups boreholes (87–66 mW/m2) at about 100 km more to the east whereas the heat flux value simulated is 73 mW/m2 in St. Loup borehole. The mean thermal gradient calculated for liassic horizons at 87 My for the Rambouillet well is 50.4 °C/km. This value is similar to previously published results. By integrating the calculation of the thermal gradients and conductivities related to the burial of each stratigraphic sequence, our approach points out variations in the thermal regimes the sedimentary organic matter (SOM) has been subjected to through geological time
Origin and standing of Canary Black Pig
We summarize the historical information about origin of Canary Black Pig and standing in the Canary Islands. The presence of pig in Canary Islands is from 500 year b.C., where aborigines used its meat as food, its fat to preserve foods, its skin as clothing and its bones to produce tools and adornments. The census is constituted for 283 animals, 182 females and 101 males, with a major representation in Tenerife and Gran Canaria islands, 173 and 71 animals respectively.A través de la documentación histórica del Archipiélago Canario, se ha esbozado el origen del Cerdo Negro Canario, a la vez que se expone su estado actual en las diferentes islas del archipiélago. La presencia del cerdo data desde hace 2500 años en el Archipiélago Canario, donde los aborígenes utilizaron su carne como alimento, su manteca para conservas, su piel para vestimenta y sus huesos para fabricación de útiles y adornos. El censo lo constituyen unos 283 ejemplares, 182 hembras y 101 machos, y su mayor representación está en las islas de Tenerife y de Gran Canaria con 173 y 71 animales respectivamente
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