pinecone/core-2020-05-10-deduplication huggingface dataset:
General Relativity Today

After recalling the conceptual foundations and the basic structure of general
relativity, we review some of its main modern developments (apart from
cosmology) : (i) the post-Newtonian limit and weak-field tests in the solar
system, (ii) strong gravitational fields and black holes, (iii) strong-field
and radiative tests in binary pulsar observations, (iv) gravitational waves,
(v) general relativity and quantum theory.Comment: 49 pages, 5 figures, talk given at the Poincar\'e Seminar
  ``Gravitation et Exp\'erience'' (28 October 2006, Paris); to appear in the
  proceedings to be published by Birkh\"ause
The Ablowitz-Ladik Hierarchy Revisited

We provide a detailed recursive construction of the Ablowitz-Ladik (AL)
hierarchy and its zero-curvature formalism. The two-coefficient AL hierarchy
under investigation can be considered a complexified version of the discrete
nonlinear Schr\"odinger equation and its hierarchy of nonlinear evolution
equations.
  Specifically, we discuss in detail the stationary Ablowitz-Ladik formalism in
connection with the underlying hyperelliptic curve and the stationary
Baker-Akhiezer function and separately the corresponding time-dependent
Ablowitz-Ladik formalism.Comment: 46 page
Is critical 2D percolation universal?

International audienceThe aim of this paper is to explore possible ways of extending Smirnov's proof of Cardy's formula for critical site-percolation on the triangular lattice to other cases (such as bond-percolation on the square lattice); the main question we address is that of the choice of the lattice embedding into the plane which gives rise to conformal invariance in the scaling limit. Even though we were not able to produce a complete proof, we believe that the ideas presented here go in the right direction
Homogenenous Multitype Fragmentations

A homogeneous mass-fragmentation, as it has been defined in [6], describes the evolution of the collection of masses of fragments of an object which breaks down into pieces as time passes. Here, we show that this model can be enriched by considering also the types of the fragments, where a type may represent, for instance, a geometrical shape, and can take finitely many values. In this setting, the dynamics of a randomly tagged fragment play a crucial role in the analysis of the fragmentation. They are determined by a Markov additive process whose distribution depends explicitly on the characteristics of the fragmentation. As applications, we make explicit the connection with multitype branching random walks, and obtain multitype analogs of the pathwise central limit theorem and large deviation estimates for the empirical distribution of fragments
Abstract kinetic equations with positive collision operators

We consider "forward-backward" parabolic equations in the abstract form $Jd
\psi / d x + L \psi = 0$, $ 0< x < \tau \leq \infty$, where $J$ and $L$ are
operators in a Hilbert space $H$ such that $J=J^*=J^{-1}$, $L=L^* \geq 0$, and
$\ker L = 0$. The following theorem is proved: if the operator $B=JL$ is
similar to a self-adjoint operator, then associated half-range boundary
problems have unique solutions. We apply this theorem to corresponding
nonhomogeneous equations, to the time-independent Fokker-Plank equation $ \mu
\frac {\partial \psi}{\partial x} (x,\mu) = b(\mu) \frac {\partial^2
\psi}{\partial \mu^2} (x, \mu)$, $ 0<x<\tau$, $ \mu \in \R$, as well as to
other parabolic equations of the "forward-backward" type. The abstract kinetic
equation $ T d \psi/dx = - A \psi (x) + f(x)$, where $T=T^*$ is injective and
$A$ satisfies a certain positivity assumption, is considered also.Comment: 20 pages, LaTeX2e, version 2, references have been added, changes in
  the introductio
Type 1,1-operators defined by vanishing frequency modulation

This paper presents a general definition of pseudo-differential operators of
type $1,1$; the definition is shown to be the largest one that is both
compatible with negligible operators and stable under vanishing frequency
modulation. Elaborating counter-examples of Ching, H\"ormander and
Parenti--Rodino, type $1,1$-operators with unclosable graphs are proved to
exist; others are shown to lack the microlocal property as they flip the
wavefront set of an almost nowhere differentiable function. In contrast the
definition is shown to imply the pseudo-local property, so type 1,1-operators
cannot create singularities but only change their nature. The familiar rule
that the support of the argument is transported by the support of the
distribution kernel is generalised to arbitrary type $1,1$-operators. A similar
spectral support rule is also proved. As no restrictions appear for classical
type $1,0$-operators, this is a new result which in many cases makes it
unnecessary to reduce to elementary symbols. As an important tool, a convergent
sequence of distributions is said to converge regularly if it moreover
converges as smooth functions outside the singular support of the limit. This
notion is shown to allow limit processes in extended versions of the formula
relating operators and kernels.Comment: 41 pages. Accepted version, with a few minor misprints corrected.
  Appeared in 2008, New development in pseudo-differential operators (eds. L.
  Rodino, M. W. Wong). Operator theory: Advances and applications, vol. 189,
  201-246. Birkh\"auser 200
Integral equations PS-3 and moduli of pants

More than a hundred years ago H.Poincare and V.A.Steklov considered a problem
for the Laplace equation with spectral parameter in the boundary conditions.
Today similar problems for two adjacent domains with the spectral parameter in
the conditions on the common boundary of the domains arises in a variety of
situations: in justification and optimization of domain decomposition method,
simple 2D models of oil extraction, (thermo)conductivity of composite
materials. Singular 1D integral Poincare-Steklov equation with spectral
parameter naturally emerges after reducing this 2D problem to the common
boundary of the domains. We present a constructive representation for the
eigenvalues and eigenfunctions of this integral equation in terms of moduli of
explicitly constructed pants, one of the simplest Riemann surfaces with
boundary. Essentially the solution of integral equation is reduced to the
solution of three transcendent equations with three unknown numbers, moduli of
pants. The discreet spectrum of the equation is related to certain surgery
procedure ('grafting') invented by B.Maskit (1969), D.Hejhal (1975) and
D.Sullivan- W.Thurston (1983).Comment: 27 pages, 13 figure
Forecasting Ability But No Profitability: An Empirical Evaluation of Genetic Algorithm-optimised Technical Trading Rules

This paper evaluates the performance of several popular technical trading rules applied to the Australian share market. The optimal trading rule parameter values over the in-sample period of 4/1/82 to 31/12/89 are found using a genetic algorithm. These optimal rules are then evaluated in terms of their forecasting ability and economic profitability during the out-of-sample period from 2/1/90 to the 31/12/97. The results indicate that the optimal rules outperform the benchmark given by a risk-adjusted buy and hold strategy. The rules display some evidence of
forecasting ability and profitability over the entire test period. But an examination of the results for the sub-periods indicates that the excess returns decline over time
and are negative during the last couple of years. Also, once an adjustment for non–synchronous trading bias is made, the rules display very little, if any, evidence of
profitability.
Regression calibration for Cox regression under heteroscedastic measurement error - Determining risk factors of cardiovascular diseases from error-prone nutritional replication data

For instance nutritional data are often subject to severe measurement error,  and an adequate adjustment of the estimators is indispensable to avoid deceptive conclusions. This paper discusses and extends the method of regression calibration to correct for measurement error in Cox regression. Special attention is paid to the modelling of quadratic predictors, the role of heteroscedastic measurement error, and the efficient use of replicated measurements of the surrogates. The method is used to analyze data from the German part of the MONICA cohort study on cardiovascular diseases. The results corroborate the importance of taking into account measurement error carefully.
EU Budget Reform Options and the Common Pool Problem

There is a consensus in the literature that the expenditure structure of the EU budget is not in line with
normative criteria based e.g. on the theory of fiscal federalism. While transfer policies have a large weight
policies of a European public good type are neglected. Our contribution explains this inefficient outcome within
the framework of a political-economic two-country model adapted from Besley and Coate (2003). The model's
modifications integrate crucial features of the EU setting such as income heterogeneity of countries, a GNI
dependent revenue formula and the existence of transfer policies in the EU budget besides both local and
European public goods. We show that the common pool problem in combination with a budget cap is at the heart
of overspending on transfers and underspending on European public goods. On the base of this model we assess
different reform options related to the revenue side. We show that the effects of an EU tax depend crucially on
the deviation of the specific tax base's redistributive effects from income proportionality. Furthermore, our
results point to the advantages of a general but limited correction mechanism
Modelling Background Noise in Finite Mixtures of Generalized Linear Regression Models

In this paper we show how only a few outliers can completely break down EM-estimation of mixtures of regression models. A simple, yet very effective way of dealing with this problem, is to use a component where all regression parameters are fixed to zero to model the background noise. This noise component can be easily defined for different types of generalized linear models, has a familiar interpretation as the empty regression model, and is not very sensitive with respect to its own parameters.
Estimation of Common Factors under Cross-Sectional and Temporal Aggregation Constraints: Nowcasting Monthly GDP and its Main Components

The paper estimates a large-scale mixed-frequency dynamic factor model for the euro area, using monthly series along with Gross Domestic Product (GDP) and its main components, obtained from the quarterly national accounts. The latter define broad measures of real economic activity (such as GDP and its decomposition by expenditure type and by branch of activity) that we are willing to include in the factor
model, in order to improve its coverage of the economy and thus the representativeness of the factors. The main problem with their inclusion is not one of model consistency, but rather of data availability and timeliness, as the national accounts series are quarterly and are available with a large publication lag. Our model is a traditional dynamic factor model formulated at the monthly frequency in terms of
the stationary representation of the variables, which however becomes nonlinear when the observational
constraints are taken into account. These are of two kinds: nonlinear temporal aggregation constraints, due to the fact that the model is formulated in terms of the unobserved monthly logarithmic changes, but we observe only the sum of the monthly levels within a quarter, and nonlinear  cross-sectional constraints, since GDP and its main components are linked by the national accounts identities, but the series are expressed in chained volumes. The paper provides an exact treatment of the observational constraints
and proposes iterative algorithms for estimating the parameters of the factor model and for signal extraction,
thereby producing nowcasts of monthly gross domestic product and its main components, as well as measures of their reliability.
Labour Market Segmentation, Flexibility and Precariousness in the Italian North East

Since the late 1970s, inequality has been on the rise in a number of OECD countries. One of the main causes of economic inequality, in Italy as in many other European countries, is rooted in the segmentation of the labour market. The Italian labour market is currently described as deeply segmented between an insider ad an outsider market. 
In the Italian manufacturing sector the quota of stable workers has declined through time and the number of unstable workers, low qualified and low paid, has increased and represents a non-marginal quota of total employment. Frequently a young worker experiments a succession of temporary contracts at the beginning of his career and develop into a more permanent position But temporary workers have, several times, a different destiny: the situation of precariousness extends to the workers’ entire career and are to be considered as an extreme case of outsiders, who operate in bad working conditions and receive low wages compared to workers hired with an open-end contract. In this research workers in manufacturing are divided between movers and stayers. Both categories show signs of instability. The quota of tenure workers over total workers decreases and movers increase through time in a significant way. Among these are permanent movers whose work histories, fragmented and chaotic, are identified and are compared with those of workers having more stable careers.
Price dispersion: the case of pasta

Scopo della ricerca è indagare la possibilità di utilizzare scanner data sugli acquisti di pasta per costruire indici dei prezzi spaziali bilaterali e multilaterali utilizzando un approccio binario nella loro costruzione.The aim of our research is to explore the possibility of utilizing scanner data on\ud
pasta purchases to build bilateral and multilateral spatial price indexes, taking a\ud
binary approach in the latter.1\ud
Pasta plays a major role in the Italian diet. Historically, pasta consumption was\ud
mainly concentrated in the Southern regions of the country but today pasta is perhaps\ud
the product most representative of the eating habits of the Italians. The range\ud
of pasta producers runs from firms of longstanding tradition (some of them mainly\ud
directed towards local markets, such as Mastromauro in Puglia) to well known\ud
international brands (such as Barilla and De Cecco).\ud
The marked increase in pasta prices over the last two years has aroused great\ud
interest, but with little focus on spatial price diversity.\ud
This study stems from the availability of an extremely detailed panel dataset\ud
(Nielsen data) on values and quantities of pasta purchased. This data was produced\ud
by the use of bar-code scanning at retail outlets and thus includes information which\ud
provides weights at an elementary level. The use of scanner data to construct price\ud
indexes is not new in literature and there is a widespread consensus on the advantages\ud
of this approach in achieving more representative indexes. Average prices (unit\ud
values) show a marked spatial price variability: even when only considering the five\ud
bestselling products, regional prices vary greatly.\ud
The paper is set out as follows: Sect. 2 provides a description of the pasta scanner\ud
dataset and briefly looks for price variability; in Sect. 3 the requirements of comparability\ud
and representativity in the case of pasta are discussed; Sect. 4 deals with\ud
the methods and formulas chosen to obtain indexes for the regional comparisons of prices; Sect. 5 shows empirical results; in Sect. 6 a brief conclusion and suggestions\ud
for future work are given
IT Value in Public Administrations: a Model Proposal for E-Procurement

Recent studies have affirmed the necessity of a discontinuity in the method of investigating the value produced in organisations by IT. Existing studies have in common a prevailing (when not exclusive) attention paid to the private sector, as testified by the frequent use of income or financial indicators to measure benefits. These approaches however cannot be directly applied to public utility organisations like public administrations. Taking into account this scenario, the present exploratory work looks at the analysis of IT investments in the public sector by identifying a viable approach to research in this domain. To move towards this objective, procurement management has been taken as the field to be observed, and an Italian publich Local Healthcare Agency which has managed several e-procurement projects has been analysed. This case represents a valuable context for examination and discussion because the outcomes of each project were evaluated in details. A riche IT Value Model devoted to the private secotr has been adopted and discussed, and later some resulting adaptations are suggested, together with some hints and limitations.Recent studies have affirmed the necessity of a discontinuity in the method of investigating the value produced in organisations by IT. Existing studies have in common a prevailing (when not exclusive) attention paid to the private sector, as testified by the frequent use of income or financial indicators to measure benefits. These approaches however cannot be directly applied to public utility organisations like public administrations. Taking into account this scenario, the present exploratory work looks at the analysis of IT investments in the public sector by identifying a viable approach to research in this domain. To move towards this objective, procurement management has been taken as the field to be observed, and an Italian publich Local Healthcare Agency which has managed several e-procurement projects has been analysed. This case represents a valuable context for examination and discussion because the outcomes of each project were evaluated in details. A riche IT Value Model devoted to the private secotr has been adopted and discussed, and later some resulting adaptations are suggested, together with some hints and limitations.Monograph's chapter
Compliance Management is Becoming a Major Issue in IS Design

This article aims at improving the information systems management support to Risk and Compliance Management process, i.e. the management of all compliance imperatives that impact an organization, including both legal and stra- tegically self-imposed imperatives. We propose a process to achieve such regula- tory compliance by aligning the Governance activities with the Risk Management ones, and we suggest Compliance should be considered as a requirement for the Risk Management platform. We will propose a framework to align law and IT compliance requirements and we will use it to underline possible directions of investigation resumed in our discussion section. This work is based on an exten- sive review of the existing literature and on the results of a four-month internship done within the IT compliance team of a major financial institution in Switzer- land, which has legal entities situated in different countries
Production Efficiency versus Ownership: The Case of China

In this study, we explore the pattern of efficiency among enterprises in China’s 29 provinces across different ownership types in heavy and light industries and across different regions (coastal, central and western).  We do so by performing a bootstrap-based analysis of group efficiencies (weighted and non-weighted), estimating and comparing densities of efficiency distributions, and conducting a bootstrapped truncated regression analysis.  We find evidence of interesting differences in efficiency levels among various ownership groups, especially for foreign and local ownership, which have different patterns for light and heavy industries.
Respecting the deal: how to manage co-opetitive actors in open innovation

Platforms like E-bay allow product seekers and providers to meet and exchange goods. On the same way in open innovation, as defined by Chesbrough, an enterprise can collect ideas from outside the company. But on E-bay, the seeker can return the product if it does not correspond to the expectations, since E-bay is the third-party actor in charge of assuring that the agreement between seekers and providers will be respected. So who does provide the same service for what concerns open innovation, where specifications might not fully defined? In this paper we shall describe the business model of an organizational structure to support the elicitation and respect of agreements between actors, who have conflicting interests but that gain from cooperating together. The concepts of the model will be illustrated to derive a set of propositions and a simple example will illustrate one of its possible instantiations. The description of our first evaluation phase shall find place at the end
Biometric Authentication and Authorization Infrastructures in Trusted Intra-Organizational Relationships

Today, the lives of both people and organizations are strongly focused on the creation, development and maintenance of relationships. These are influenced by several factors, amongst which trust plays an important role. Same as in traditional relationships, trust is considered crucial in their digital equivalent; here we can speak of the concept of trust in technology. An example for trust in technology is given by biometric authentication and authorization infrastructures. A possible approach is the use of typing behavior biometrics as authentication method. This provides a higher security, considering several biometric specific problems like replay attacks or template aging. The intra-organizational environment allows an interesting solution to these problems, namely the synchronization of biometric data within a federation of applications running in the same company. This paper presents the influence of the proposed authentication model on trust by means of the technical-formal-informal model inside an organization.Today, the lives of both people and organizations are strongly focused on the creation, development and maintenance of relationships. These are influenced by several factors, amongst which trust plays an important role. Same as in traditional relationships, trust is considered crucial in their digital equivalent; here we can speak of the concept of trust in technology. An example for trust in technology is given by biometric authentication and authorization infrastructures. A possible approach is the use of typing behavior biometrics as authentication method. This provides a higher security, considering several biometric specific problems like replay attacks or template aging. The intra-organizational environment allows an interesting solution to these problems, namely the synchronization of biometric data within a federation of applications running in the same company. This paper presents the influence of the proposed authentication model on trust by means of the technical-formal-informal model inside an organization.Monograph's chapter
Asymptotic properties of adaptive penalized optimal designs over a finite space

International audienceAdaptive optimal design with a cost constraint is considered, both for LS estimation in nonlinear regression and ML estimation in Bernoulli-type experiments, with possible applications in clinical trials. We obtain the strong consistency of the estimators for designs over a finite space, both when the cost level is fixed (and the adaptive design converges to an optimum constrained design) and when the objective is to minimize the cost. Moreover, the asymptotic normality of the estimators is obtained in the first situation, with an asymptotic covariance matrix given by the inverse of the usual information matrix, calculated as if the design were not constructed sequentially