Home  About us  Contact
 

Well-known Results (well-known + result)

Distribution by Scientific Domains
Mathematics and Statistics22%
Business, Economics, Finance and Accounting22%

Selected Abstracts

Toward a general theory of conditional beliefs

INTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 3 2006
Giulianella Coletti
We consider a class of general decomposable measures of uncertainty, which encompasses (as its most specific elements, with respect to the properties of the rules of composition) probabilities, and (as its most general elements) belief functions. The aim, using this general context, is to introduce (in a direct way) the concept of conditional belief function as a conditional generalized decomposable measure ,(·|·), defined on a set of conditional events. Our main tool will be the following result, that we prove in the first part of the article and which is a sort of converse of a well-known result (i.e., a belief function is a lower probability): a coherent conditional lower probability P(·|K) extending a coherent probability P(Hi),where the events His are a partition of the certain event , and K is the union of some (possibly all) of them,is a belief function. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 229,259, 2006. [source]

Domestic dogs as an edge effect in the Brasília National Park, Brazil: interactions with native mammals

ANIMAL CONSERVATION, Issue 5 2009
A. C. R. Lacerda
Abstract Edge effects are a well-known result of habitat fragmentation. However, little has been published on fragmentation, isolation and the intrusive influence from the surrounding matrix at the landscape level. The objectives of the present study are to evaluate the presence of dogs in the Brasília National Park (BNP) in relation to habitat type and the influence from the surrounding matrix. In addition, this study examines the response of the native mammal fauna to the presence of dogs. Track stations were built along dirt roads in the BNP and subsequently examined for the presence or absence of tracks. We used a stepwise logistic regression to model the occurrence of five mammal species relative to habitat variables, with an ,=0.05 to determine whether to enter and retain a variable in the model. A simulation of each species occurrence probability was conducted using a combination of selected habitat variables in a resource selection probability function. Results indicate a negative relationship between distance from the BNP edge and the probability of dog occurrences. From an ecological perspective, the presence of dogs inside the BNP indicates an edge effect. The occurrence of the maned wolf was positively associated with distance from a garbage dump site and negatively associated with the presence of dog tracks. The maned wolf and giant anteater seem to avoid areas near the garbage dump as well as areas with dog tracks. There is no support for the possible existence of a feral dog population inside the BNP, but the effects of free-ranging dogs on the wildlife population in such an isolated protected area must not be neglected. Domestic dog Canis familiaris populations and disease control programs should be established in the urban, sub-urban and rural areas surrounding the BNP, along with the complete removal of the garbage dump from the BNP surroundings. [source]

In Situ Spectroscopic Characterization of Rectifying Molecular Monolayers Self-Assembled on Gold

CHEMPHYSCHEM, Issue 15 2007
Alberto Girlando Prof.
Abstract We report visible, Raman, and infrared spectra of self-assembled monolayers (SAMs) formed by the donor-(,-bridge)-acceptor chromophore, Z -,-[N -(,-acetylthioalkyl)-4-quinolinium]-,-cyano-4-styryldicyanomethanide (CH3CO-S-CnH2n -Q3CNQ where n=8, 10), on gold-coated substrates. The data are compared with the spectra collected for the same compound in solution and in the solid state, and with those obtained for a Langmuir,Blodgett (LB) monolayer of C16H33 -Q3CNQ deposited on gold. Spectral analysis confirms that in solution, in the solid state and in the LB film the chromophore has a zwitterionic (D+ -,-A,) ground state. At variance with this well-known result, our data show that in SAMs deposited on gold the chromophore has a more neutral, quinoid ground state. We relate this difference to the different packing of the molecules in the two different films: in SAMs in fact the chromophores stand almost vertical with respect to the substrate, whereas in LB films they make an angle of about 45 degrees. The Q3CNQ molecule is a well-known molecular rectifier, and for SAMs we were able to check the direction of electron flow at forward bias on the same samples that have been characterized spectroscopically, shedding light on the rectification mechanism. [source]

A reexamination of corporate risks under shadow costs of incomplete information

INTERNATIONAL JOURNAL OF FINANCE & ECONOMICS, Issue 1 2001
Mondher Bellalah
G3; G31; G32; G33 Abstract The valuation of the firm and its assets has been done for a long time in the classic context of complete information. Several empirical tests of the main valuation methods reveal a divergence between theoretical prices and observed prices. These deviations might be explained by the standard assumptions of complete information. It is possible to introduce information uncertainty as done by Merton and by Bellalah in the reexamination of corporate risks in the presence of information costs. The concept of risk is useful in modelling the value of the firm and its business risk and in the definition of the required rates of return and the cost of capital of corporations. However, the main well-known results ignore information uncertainty as defined by Merton. Using the main results from the study of Modigliani and Miller and the implications of Merton's model, we give expressions for the cost of capital and the value of the firm's equity and debt in the presence of information costs. We reexamine the relationships between interrelated risks in the same context. We introduce information costs in the computation of the cost of capital and in the pricing of equity in an option framework. When there are no information costs, the main relationships reduce to the classic results in the literature. Copyright © 2001 John Wiley & Sons, Ltd. [source]

A post Keynesian critique of privatization policies in transition economies

JOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 5 2002
John Marangos
The privatization policies implemented in transition economies were based on the neoclassical principles of economic thought. The neoclassical privatization policies contributed to the well-known results of a large reduction in output, high unemployment and inflation and a breakdown of institutional norms resulting in corruption and illegal activities. For the post Keynesians, there could have been a transition to a market economy without a substantial change in property ownership. This was because ownership, as such, was less important than competition, the incentive structure and the nature of regulatory policies. Consequently, post Keynesian policies of privatization would had resulted in a substantially smaller social cost of transition. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Simulations of the heating of the Galactic stellar disc

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2002
Jyrki Hänninen
ABSTRACT The velocity dispersion of nearby stars in the Galactic disc is well known to increase substantially with age; this is the so-called age,velocity relation, and is interpreted as a ,heating' of the disc as a function of time. We have studied the heating of the Galactic stellar disc caused by giant molecular clouds and halo black holes, via simulations of the orbits of tracer stars embedded in a patch of the local Galactic disc. We examine a range of masses and number densities of the giant molecular cloud and halo black hole perturbers. The heating of the stellar disc in the simulations is fitted with a simple power law of the form ,,t,, where , is the velocity dispersion of the tracer stars as a function of time, t. We also fit this form to the best determinations of the increase in the velocity dispersion as a function of time as derived from stars in the solar neighbourhood for which ages can be reliably assigned. Observationally, , is found to lie in the range 0.3,0.6, i.e. it remains poorly constrained and its determination is probably still dominated by systematic errors. Better constrained observationally is the ratio of the velocity dispersions of the stars in the vertical z and horizontal x directions (i.e. towards the Galactic Centre), ,z/,x= 0.5 ± 0.1. For the heating of the stellar disc caused by giant molecular clouds (GMCs) we derive a heating ,,t0.21, which differs somewhat from early (analytic) studies in which ,,t1/4. This confirms the well-known results that there are insufficient GMCs to heat the Galactic disc appropriately. A range of dark halo black hole scenarios are verified to heat the stellar disc as ,,t1/2 (as expected from analytical studies), and give ,z/,x in the range 0.5,0.6, which is consistent with observations. Black holes with a mass of 107 M, are our favoured disc heaters, although they are only marginally consistent with observations. Simulations featuring a combination of giant molecular clouds and halo black holes can explain the observed heating of the stellar disc, but since other perturbing mechanisms, such as spiral arms, are yet to be included, we regard this solution as being ad hoc. [source]

The absolute center of a network,

NETWORKS: AN INTERNATIONAL JOURNAL, Issue 2 2004
Dov Dvir
Abstract This paper presents a new algorithm for finding an absolute center (minimax criterion) of an undirected network with n nodes and m arcs based on the concept of minimum-diameter trees. Local centers and their associated radii are identified by a monotonically increasing sequence of lower bounds on the radii. Computational efficiency is addressed in terms of worst-case complexity and practical performance. The complexity of the algorithm is 0(n2 ,g n + mn). In practice, because of its very rapid convergence, the algorithm renders the problem amenable even to manual solution for quite large networks, provided that the minimal-distance matrix is given. Otherwise, evaluation of this matrix is the effective computational bottleneck. An interesting feature of the algorithm and its theoretical foundations is that it synthesizes and generalizes some well-known results in this area, particularly Halpern's lower bound on the local radius of a network and properties of centers of tree networks. © 2004 Wiley Periodicals, Inc. [source]

Two characterizations of matrices with the Perron,Frobenius property

NUMERICAL LINEAR ALGEBRA WITH APPLICATIONS, Issue 11-12 2009
Abed Elhashash
Abstract Two characterizations of general matrices for which the spectral radius is an eigenvalue and the corresponding eigenvector is either positive or nonnegative are presented. One is a full characterization in terms of the sign of the entries of the spectral projector. In another case, different necessary and sufficient conditions are presented that relate to the classes of the matrix. These characterizations generalize well-known results for nonnegative matrices. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Fair Procedures: Evidence from Games Involving Lotteries,

THE ECONOMIC JOURNAL, Issue 506 2005
Gary E Bolton
Procedures are the area where fairness arguably has its largest influence on modern societies. The experiments we report provide an initial characterisation of that influence and suggest new interpretations for some well-known results. We find that procedural fairness is conceptually distinct from allocation fairness, although the evidence also indicates that the two are linked in important ways. Post hoc extension of one of the current models of fairness illustrates this link and implies that a deeper understanding of procedural fairness will require investigation of competing fairness norms. If a number of persons engage in a series of fair bets, the distribution of cash after the last bet is fair, or at least not unfair, whatever this distribution is. John Rawls (1971) [source]