2,857 research outputs found
Private benefits extraction in closely-held corporations: The case for multiple large shareholders*
This paper investigates how multiple large shareholders share control and extract private benefits in closely-held corporations. We find that ownership structures with multiple large shareholders are common and very stable. Moreover, they seem to be, to a large extent, exogenously given. The structure of the controlling group of shareholders has a very significant impact on performance. Performance improves as the control groupâs ownership stake increases and, for a given ownership stake, as the number of members increases. The economic significance of the effects indicates that minority expropriation is a very important problem in closely-held firms.
Exploring the link between employment search time and reservation wages in Southern Europe
In our piece of work we are facing a two-fold problem: on the one hand, we study the behaviour of job seekers and the extent to which reservation wages and unemployment benefits play a relevant role in the transition into working life. On the other hand, we intend to find out whether the determinants of the job search process may also affect subsequent wages.transiciones laborales, prestaciones por desempleo, salarios de reserva, ganancias,earnings, transitions into work, unemployment benefits, reservation wages.
A characterization of dual quermassintegrals and the roots of dual steiner polynomials
For any finite with , we provide a
characterization of those tuples of positive numbers
which are dual querma\ss integrals of two star bodies. It turns out that this
problem is related to the moment problem. Based on this relation we also get
new inequalities for the dual querma\ss integrals. Moreover, the above
characterization will be the key tool in order to investigate structural
properties of the set of roots of dual Steiner polynomials of star bodies
Salt effect on sensitized photooxidations. A kinetic approch to environmental decomposition of marine contaminants
The salt effect on the kinetics of singlet molecular oxygen [O2(1Îg)]-mediated photooxidations of sea water contaminants was investigated. Two families of photooxidizable compounds were employed in the study: anthracene derivatives and phenols. The presence of salt (NaCl in H2O and LiCl in MeCN, in both cases in the range 0-0.45 M) produces changes in the photooxidation rate. For solvent-polarity-dependent reactions, this behavior can be predicted, by knowing the solvent-polarity dependence of the rate constant for chemical reaction of the substrates with O2(1Î g) in non-saline solutions (kr). For the cases of photooxidations possessing solvent-polarity-independent or scantily-dependent kr values, the photooxidation rates decrease as the salt content in the solution increases, mainly due to a predominance of the physical quenching pathway. In addition, the quantum yield for O2(1 Îg) generation (ΊÎ) was determined in a series of saline solutions, in the range of 0-0.45 M in water and MeCN solutions, in the presence of NaCl and LiCl respectively. The Î values are independent, within the experimental error on the salt content.No disponibl
Relationship between Ocular Surface Alterations and Concentrations of Aerial Particulate Matter
Purpose: To evaluate ocular surface alterations in two populations at different exposure levels to particulate matter (PM) in their living and work environments.
Methods: A cross-sectional study was conducted, including 78 volunteers from Argentina who lived and worked under different pollution levels in an urban (U; n = 44) or industrial zone (I; n = 34). Mean exposure level to PM was evaluated. Responses to the Ocular Symptom Disease Index and McMonnies questionnaire were obtained from all subjects. Subsequently, an assessment through the Schirmer I test (ST), slit lamp microscopy, vital staining, and tear breakup time was conducted. Statistical analyses with Chi-square and Bartlettâs tests, as well as Studentâs t-tests and principal component analysis (PCA), were performed.
Results: Particles of size < 2.5 ÎŒm (PM2.5) level was significantly higher in the I group than the U group (P = 0.04). Ocular surface parameters including bulbar redness, eyelid redness, and the degree of vital staining with fluorescein (SF) and lissamine green (SLG) exhibited difference between the groups. With regards to the tear film, statistically significant differences in the ST value and meibomian gland dysfunction between the groups were detected (P = 0.003 and P = 0.02, respectively). Conjunctival SF and SLG, and ST values were identified as factors which could distinguish groups exposed to different PM levels.
Conclusion: Subjects exposed to higher levels of PM in the outdoor air presented greater ocular surface alterations. Thus, ST, SF, and SLG values could be used as convenient indicators of adverse health effects due to exposure to air pollution
Projection based ensemble learning for ordinal regression
The classification of patterns into naturally ordered
labels is referred to as ordinal regression. This paper proposes
an ensemble methodology specifically adapted to this type of
problems, which is based on computing different classification
tasks through the formulation of different order hypotheses.
Every single model is trained in order to distinguish between
one given class (k) and all the remaining ones, but grouping
them in those classes with a rank lower than k, and those
with a rank higher than k. Therefore, it can be considered as
a reformulation of the well-known one-versus-all scheme. The
base algorithm for the ensemble could be any threshold (or
even probabilistic) method, such as the ones selected in this
paper: kernel discriminant analysis, support vector machines
and logistic regression (all reformulated to deal with ordinal
regression problems). The method is seen to be competitive when
compared with other state-of-the-art methodologies (both ordinal
and nominal), by using six measures and a total of fifteen ordinal
datasets. Furthermore, an additional set of experiments is used to
study the potential scalability and interpretability of the proposed
method when using logistic regression as base methodology for
the ensemble
Borderline kernel based over-sampling
Nowadays, the imbalanced nature of some real-world data
is receiving a lot of attention from the pattern recognition and machine
learning communities in both theoretical and practical aspects, giving
rise to di erent promising approaches to handling it. However, preprocessing
methods operate in the original input space, presenting distortions
when combined with kernel classi ers, that operate in the feature
space induced by a kernel function. This paper explores the notion of
empirical feature space (a Euclidean space which is isomorphic to the feature
space and therefore preserves its structure) to derive a kernel-based
synthetic over-sampling technique based on borderline instances which
are considered as crucial for establishing the decision boundary. Therefore,
the proposed methodology would maintain the main properties of
the kernel mapping while reinforcing the decision boundaries induced by
a kernel machine. The results show that the proposed method achieves
better results than the same borderline over- sampling method applied
in the original input spac
A Practical Environment to Apply Model-Driven Web Engineering
The application of a model-driven paradigm in the development of Web Systems has yielded very good research
results. Several research groups are defining metamodels, transformations, and tools which offer a suitable environment,
known as model-driven Web engineering (MDWE). However, there are very few practical experiences in real
Web system developments using real development teams. This chapter presents a practical environment of MDWE
based on the use of NDT (navigational development techniques) and Java Web systems, and it provides a practical
evaluation of its application within a real project: specialized Diraya.Ministerio de EducaciĂłn y Ciencia TIN2007-67843-C06-03Ministerio de EducaciĂłn y Ciencia TIN2007-30391-
Nuevas aportaciones al estudio polĂnico de sedimentos del Parque Natural de los Alcornocales (CĂĄdiz, sur de España)
Nuevas apotaciones al estudio polĂnico de sedimentos del Parque Natural de los Alcornocales (CĂĄdiz, Sur de España). En este trabajo se completa el contenido polĂnico de una columna de sedimento de 300 cm, extraida de una zona semiturbosa de la Sierra del Aljibe en el Parque Natural de los Alcornocales (CĂĄdiz). Se discuten las variaciones polĂnicas porcentuales de los taxones identificados, consideradas de nuevo aquĂ a la luz de los nuevos datos, fundamentalmente la dataciĂłn con radiocarbono, y se interpretan los diagramas polĂnicos resultantes en tĂ©rminos paleoecolĂłgicos. Por otro lado, y en base a estudios previos en el norte de Marruecos, zona de caracterĂsticas ecolĂłgicas e histĂłricas similares a la zona estudiada, se concluye el uso diferente del territorio a ambos lados del estrecho
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